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KCSAN updates for v5.17

Browse source 
This series provides KCSAN fixes and also the ability to take memory
 barriers into account for weakly-ordered systems.  This last can increase
 the probability of detecting certain types of data races.
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Merge tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:
 "This provides KCSAN fixes and also the ability to take memory barriers
  into account for weakly-ordered systems. This last can increase the
  probability of detecting certain types of data races"

* tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits)
  kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it
  kcsan: Avoid nested contexts reading inconsistent reorder_access
  kcsan: Turn barrier instrumentation into macros
  kcsan: Make barrier tests compatible with lockdep
  kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
  compiler_attributes.h: Add __disable_sanitizer_instrumentation
  objtool, kcsan: Remove memory barrier instrumentation from noinstr
  objtool, kcsan: Add memory barrier instrumentation to whitelist
  sched, kcsan: Enable memory barrier instrumentation
  mm, kcsan: Enable barrier instrumentation
  x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock()
  x86/barriers, kcsan: Use generic instrumentation for non-smp barriers
  asm-generic/bitops, kcsan: Add instrumentation for barriers
  locking/atomics, kcsan: Add instrumentation for barriers
  locking/barriers, kcsan: Support generic instrumentation
  locking/barriers, kcsan: Add instrumentation for barriers
  kcsan: selftest: Add test case to check memory barrier instrumentation
  kcsan: Ignore GCC 11+ warnings about TSan runtime support
  kcsan: test: Add test cases for memory barrier instrumentation
  kcsan: test: Match reordered or normal accesses
  ...
This commit is contained in:
Linus Torvalds 2022-01-11 09:51:26 -08:00
parent 1c824bf768 b473a3891c
commit 1be5bdf8cd
27 changed files with 1346 additions and 171 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

74
Documentation/dev-tools/kcsan.rst
View file

@ -204,17 +204,17 @@ Ultimately this allows to determine the possible executions of concurrent code,
and if that code is free from data races.
KCSAN is aware of *marked atomic operations* (``READ_ONCE``, ``WRITE_ONCE``,
``atomic_*``, etc.), but is oblivious of any ordering guarantees and simply
assumes that memory barriers are placed correctly. In other words, KCSAN
assumes that as long as a plain access is not observed to race with another
conflicting access, memory operations are correctly ordered.
``atomic_*``, etc.), and a subset of ordering guarantees implied by memory
barriers. With ``CONFIG_KCSAN_WEAK_MEMORY=y``, KCSAN models load or store
buffering, and can detect missing ``smp_mb()``, ``smp_wmb()``, ``smp_rmb()``,
``smp_store_release()``, and all ``atomic_*`` operations with equivalent
implied barriers.
This means that KCSAN will not report *potential* data races due to missing
memory ordering. Developers should therefore carefully consider the required
memory ordering requirements that remain unchecked. If, however, missing
memory ordering (that is observable with a particular compiler and
architecture) leads to an observable data race (e.g. entering a critical
section erroneously), KCSAN would report the resulting data race.
Note, KCSAN will not report all data races due to missing memory ordering,
specifically where a memory barrier would be required to prohibit subsequent
memory operation from reordering before the barrier. Developers should
therefore carefully consider the required memory ordering requirements that
remain unchecked.
Race Detection Beyond Data Races
--------------------------------
@ -268,6 +268,56 @@ marked operations, if all accesses to a variable that is accessed concurrently
are properly marked, KCSAN will never trigger a watchpoint and therefore never
report the accesses.
Modeling Weak Memory
~~~~~~~~~~~~~~~~~~~~
KCSAN's approach to detecting data races due to missing memory barriers is
based on modeling access reordering (with ``CONFIG_KCSAN_WEAK_MEMORY=y``).
Each plain memory access for which a watchpoint is set up, is also selected for
simulated reordering within the scope of its function (at most 1 in-flight
access).
Once an access has been selected for reordering, it is checked along every
other access until the end of the function scope. If an appropriate memory
barrier is encountered, the access will no longer be considered for simulated
reordering.
When the result of a memory operation should be ordered by a barrier, KCSAN can
then detect data races where the conflict only occurs as a result of a missing
barrier. Consider the example::
int x, flag;
void T1(void)
{
x = 1; // data race!
WRITE_ONCE(flag, 1); // correct: smp_store_release(&flag, 1)
}
void T2(void)
{
while (!READ_ONCE(flag)); // correct: smp_load_acquire(&flag)
... = x; // data race!
}
When weak memory modeling is enabled, KCSAN can consider ``x`` in ``T1`` for
simulated reordering. After the write of ``flag``, ``x`` is again checked for
concurrent accesses: because ``T2`` is able to proceed after the write of
``flag``, a data race is detected. With the correct barriers in place, ``x``
would not be considered for reordering after the proper release of ``flag``,
and no data race would be detected.
Deliberate trade-offs in complexity but also practical limitations mean only a
subset of data races due to missing memory barriers can be detected. With
currently available compiler support, the implementation is limited to modeling
the effects of "buffering" (delaying accesses), since the runtime cannot
"prefetch" accesses. Also recall that watchpoints are only set up for plain
accesses, and the only access type for which KCSAN simulates reordering. This
means reordering of marked accesses is not modeled.
A consequence of the above is that acquire operations do not require barrier
instrumentation (no prefetching). Furthermore, marked accesses introducing
address or control dependencies do not require special handling (the marked
access cannot be reordered, later dependent accesses cannot be prefetched).
Key Properties
~~~~~~~~~~~~~~
@ -290,8 +340,8 @@ Key Properties
4. **Detects Racy Writes from Devices:** Due to checking data values upon
setting up watchpoints, racy writes from devices can also be detected.
5. **Memory Ordering:** KCSAN is *not* explicitly aware of the LKMM's ordering
rules; this may result in missed data races (false negatives).
5. **Memory Ordering:** KCSAN is aware of only a subset of LKMM ordering rules;
this may result in missed data races (false negatives).
6. **Analysis Accuracy:** For observed executions, due to using a sampling
strategy, the analysis is *unsound* (false negatives possible), but aims to

10
arch/x86/include/asm/barrier.h
View file

@ -19,9 +19,9 @@
#define wmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "sfence", \
X86_FEATURE_XMM2) ::: "memory", "cc")
#else
#define mb() asm volatile("mfence":::"memory")
#define rmb() asm volatile("lfence":::"memory")
#define wmb() asm volatile("sfence" ::: "memory")
#define __mb() asm volatile("mfence":::"memory")
#define __rmb() asm volatile("lfence":::"memory")
#define __wmb() asm volatile("sfence" ::: "memory")
#endif
/**
@ -51,8 +51,8 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
/* Prevent speculative execution past this barrier. */
#define barrier_nospec() alternative("", "lfence", X86_FEATURE_LFENCE_RDTSC)
#define dma_rmb() barrier()
#define dma_wmb() barrier()
#define __dma_rmb() barrier()
#define __dma_wmb() barrier()
#define __smp_mb() asm volatile("lock; addl $0,-4(%%" _ASM_SP ")" ::: "memory", "cc")

1
arch/x86/include/asm/qspinlock.h
View file

@ -53,6 +53,7 @@ static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
static inline void queued_spin_unlock(struct qspinlock *lock)
{
kcsan_release();
pv_queued_spin_unlock(lock);
}

54
include/asm-generic/barrier.h
View file

@ -14,12 +14,38 @@
#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <linux/kcsan-checks.h>
#include <asm/rwonce.h>
#ifndef nop
#define nop() asm volatile ("nop")
#endif
/*
* Architectures that want generic instrumentation can define __ prefixed
* variants of all barriers.
*/
#ifdef __mb
#define mb() do { kcsan_mb(); __mb(); } while (0)
#endif
#ifdef __rmb
#define rmb() do { kcsan_rmb(); __rmb(); } while (0)
#endif
#ifdef __wmb
#define wmb() do { kcsan_wmb(); __wmb(); } while (0)
#endif
#ifdef __dma_rmb
#define dma_rmb() do { kcsan_rmb(); __dma_rmb(); } while (0)
#endif
#ifdef __dma_wmb
#define dma_wmb() do { kcsan_wmb(); __dma_wmb(); } while (0)
#endif
/*
* Force strict CPU ordering. And yes, this is required on UP too when we're
* talking to devices.
@ -62,15 +88,15 @@
#ifdef CONFIG_SMP
#ifndef smp_mb
#define smp_mb() __smp_mb()
#define smp_mb() do { kcsan_mb(); __smp_mb(); } while (0)
#endif
#ifndef smp_rmb
#define smp_rmb() __smp_rmb()
#define smp_rmb() do { kcsan_rmb(); __smp_rmb(); } while (0)
#endif
#ifndef smp_wmb
#define smp_wmb() __smp_wmb()
#define smp_wmb() do { kcsan_wmb(); __smp_wmb(); } while (0)
#endif
#else /* !CONFIG_SMP */
@ -123,19 +149,19 @@ do { \
#ifdef CONFIG_SMP
#ifndef smp_store_mb
#define smp_store_mb(var, value) __smp_store_mb(var, value)
#define smp_store_mb(var, value) do { kcsan_mb(); __smp_store_mb(var, value); } while (0)
#endif
#ifndef smp_mb__before_atomic
#define smp_mb__before_atomic() __smp_mb__before_atomic()
#define smp_mb__before_atomic() do { kcsan_mb(); __smp_mb__before_atomic(); } while (0)
#endif
#ifndef smp_mb__after_atomic
#define smp_mb__after_atomic() __smp_mb__after_atomic()
#define smp_mb__after_atomic() do { kcsan_mb(); __smp_mb__after_atomic(); } while (0)
#endif
#ifndef smp_store_release
#define smp_store_release(p, v) __smp_store_release(p, v)
#define smp_store_release(p, v) do { kcsan_release(); __smp_store_release(p, v); } while (0)
#endif
#ifndef smp_load_acquire
@ -178,13 +204,13 @@ do { \
#endif /* CONFIG_SMP */
/* Barriers for virtual machine guests when talking to an SMP host */
#define virt_mb() __smp_mb()
#define virt_rmb() __smp_rmb()
#define virt_wmb() __smp_wmb()
#define virt_store_mb(var, value) __smp_store_mb(var, value)
#define virt_mb__before_atomic() __smp_mb__before_atomic()
#define virt_mb__after_atomic() __smp_mb__after_atomic()
#define virt_store_release(p, v) __smp_store_release(p, v)
#define virt_mb() do { kcsan_mb(); __smp_mb(); } while (0)
#define virt_rmb() do { kcsan_rmb(); __smp_rmb(); } while (0)
#define virt_wmb() do { kcsan_wmb(); __smp_wmb(); } while (0)
#define virt_store_mb(var, value) do { kcsan_mb(); __smp_store_mb(var, value); } while (0)
#define virt_mb__before_atomic() do { kcsan_mb(); __smp_mb__before_atomic(); } while (0)
#define virt_mb__after_atomic() do { kcsan_mb(); __smp_mb__after_atomic(); } while (0)
#define virt_store_release(p, v) do { kcsan_release(); __smp_store_release(p, v); } while (0)
#define virt_load_acquire(p) __smp_load_acquire(p)
/**

3
include/asm-generic/bitops/instrumented-atomic.h
View file

@ -67,6 +67,7 @@ static inline void change_bit(long nr, volatile unsigned long *addr)
*/
static inline bool test_and_set_bit(long nr, volatile unsigned long *addr)
{
kcsan_mb();
instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));
return arch_test_and_set_bit(nr, addr);
}
@ -80,6 +81,7 @@ static inline bool test_and_set_bit(long nr, volatile unsigned long *addr)
*/
static inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)
{
kcsan_mb();
instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));
return arch_test_and_clear_bit(nr, addr);
}
@ -93,6 +95,7 @@ static inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)
*/
static inline bool test_and_change_bit(long nr, volatile unsigned long *addr)
{
kcsan_mb();
instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));
return arch_test_and_change_bit(nr, addr);
}

3
include/asm-generic/bitops/instrumented-lock.h
View file

@ -22,6 +22,7 @@
*/
static inline void clear_bit_unlock(long nr, volatile unsigned long *addr)
{
kcsan_release();
instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));
arch_clear_bit_unlock(nr, addr);
}
@ -37,6 +38,7 @@ static inline void clear_bit_unlock(long nr, volatile unsigned long *addr)
*/
static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
{
kcsan_release();
instrument_write(addr + BIT_WORD(nr), sizeof(long));
arch___clear_bit_unlock(nr, addr);
}
@ -71,6 +73,7 @@ static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr)
static inline bool
clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr)
{
kcsan_release();
instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));
return arch_clear_bit_unlock_is_negative_byte(nr, addr);
}

135
include/linux/atomic/atomic-instrumented.h
View file

@ -45,6 +45,7 @@ atomic_set(atomic_t *v, int i)
static __always_inline void
atomic_set_release(atomic_t *v, int i)
{
kcsan_release();
instrument_atomic_write(v, sizeof(*v));
arch_atomic_set_release(v, i);
}
@ -59,6 +60,7 @@ atomic_add(int i, atomic_t *v)
static __always_inline int
atomic_add_return(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_add_return(i, v);
}
@ -73,6 +75,7 @@ atomic_add_return_acquire(int i, atomic_t *v)
static __always_inline int
atomic_add_return_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_add_return_release(i, v);
}
@ -87,6 +90,7 @@ atomic_add_return_relaxed(int i, atomic_t *v)
static __always_inline int
atomic_fetch_add(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_add(i, v);
}
@ -101,6 +105,7 @@ atomic_fetch_add_acquire(int i, atomic_t *v)
static __always_inline int
atomic_fetch_add_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_add_release(i, v);
}
@ -122,6 +127,7 @@ atomic_sub(int i, atomic_t *v)
static __always_inline int
atomic_sub_return(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_sub_return(i, v);
}
@ -136,6 +142,7 @@ atomic_sub_return_acquire(int i, atomic_t *v)
static __always_inline int
atomic_sub_return_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_sub_return_release(i, v);
}
@ -150,6 +157,7 @@ atomic_sub_return_relaxed(int i, atomic_t *v)
static __always_inline int
atomic_fetch_sub(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_sub(i, v);
}
@ -164,6 +172,7 @@ atomic_fetch_sub_acquire(int i, atomic_t *v)
static __always_inline int
atomic_fetch_sub_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_sub_release(i, v);
}
@ -185,6 +194,7 @@ atomic_inc(atomic_t *v)
static __always_inline int
atomic_inc_return(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_inc_return(v);
}
@ -199,6 +209,7 @@ atomic_inc_return_acquire(atomic_t *v)
static __always_inline int
atomic_inc_return_release(atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_inc_return_release(v);
}
@ -213,6 +224,7 @@ atomic_inc_return_relaxed(atomic_t *v)
static __always_inline int
atomic_fetch_inc(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_inc(v);
}
@ -227,6 +239,7 @@ atomic_fetch_inc_acquire(atomic_t *v)
static __always_inline int
atomic_fetch_inc_release(atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_inc_release(v);
}
@ -248,6 +261,7 @@ atomic_dec(atomic_t *v)
static __always_inline int
atomic_dec_return(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_dec_return(v);
}
@ -262,6 +276,7 @@ atomic_dec_return_acquire(atomic_t *v)
static __always_inline int
atomic_dec_return_release(atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_dec_return_release(v);
}
@ -276,6 +291,7 @@ atomic_dec_return_relaxed(atomic_t *v)
static __always_inline int
atomic_fetch_dec(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_dec(v);
}
@ -290,6 +306,7 @@ atomic_fetch_dec_acquire(atomic_t *v)
static __always_inline int
atomic_fetch_dec_release(atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_dec_release(v);
}
@ -311,6 +328,7 @@ atomic_and(int i, atomic_t *v)
static __always_inline int
atomic_fetch_and(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_and(i, v);
}
@ -325,6 +343,7 @@ atomic_fetch_and_acquire(int i, atomic_t *v)
static __always_inline int
atomic_fetch_and_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_and_release(i, v);
}
@ -346,6 +365,7 @@ atomic_andnot(int i, atomic_t *v)
static __always_inline int
atomic_fetch_andnot(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_andnot(i, v);
}
@ -360,6 +380,7 @@ atomic_fetch_andnot_acquire(int i, atomic_t *v)
static __always_inline int
atomic_fetch_andnot_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_andnot_release(i, v);
}
@ -381,6 +402,7 @@ atomic_or(int i, atomic_t *v)
static __always_inline int
atomic_fetch_or(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_or(i, v);
}
@ -395,6 +417,7 @@ atomic_fetch_or_acquire(int i, atomic_t *v)
static __always_inline int
atomic_fetch_or_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_or_release(i, v);
}
@ -416,6 +439,7 @@ atomic_xor(int i, atomic_t *v)
static __always_inline int
atomic_fetch_xor(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_xor(i, v);
}
@ -430,6 +454,7 @@ atomic_fetch_xor_acquire(int i, atomic_t *v)
static __always_inline int
atomic_fetch_xor_release(int i, atomic_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_xor_release(i, v);
}
@ -444,6 +469,7 @@ atomic_fetch_xor_relaxed(int i, atomic_t *v)
static __always_inline int
atomic_xchg(atomic_t *v, int i)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_xchg(v, i);
}
@ -458,6 +484,7 @@ atomic_xchg_acquire(atomic_t *v, int i)
static __always_inline int
atomic_xchg_release(atomic_t *v, int i)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_xchg_release(v, i);
}
@ -472,6 +499,7 @@ atomic_xchg_relaxed(atomic_t *v, int i)
static __always_inline int
atomic_cmpxchg(atomic_t *v, int old, int new)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_cmpxchg(v, old, new);
}
@ -486,6 +514,7 @@ atomic_cmpxchg_acquire(atomic_t *v, int old, int new)
static __always_inline int
atomic_cmpxchg_release(atomic_t *v, int old, int new)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_cmpxchg_release(v, old, new);
}
@ -500,6 +529,7 @@ atomic_cmpxchg_relaxed(atomic_t *v, int old, int new)
static __always_inline bool
atomic_try_cmpxchg(atomic_t *v, int *old, int new)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
instrument_atomic_read_write(old, sizeof(*old));
return arch_atomic_try_cmpxchg(v, old, new);
@ -516,6 +546,7 @@ atomic_try_cmpxchg_acquire(atomic_t *v, int *old, int new)
static __always_inline bool
atomic_try_cmpxchg_release(atomic_t *v, int *old, int new)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
instrument_atomic_read_write(old, sizeof(*old));
return arch_atomic_try_cmpxchg_release(v, old, new);
@ -532,6 +563,7 @@ atomic_try_cmpxchg_relaxed(atomic_t *v, int *old, int new)
static __always_inline bool
atomic_sub_and_test(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_sub_and_test(i, v);
}
@ -539,6 +571,7 @@ atomic_sub_and_test(int i, atomic_t *v)
static __always_inline bool
atomic_dec_and_test(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_dec_and_test(v);
}
@ -546,6 +579,7 @@ atomic_dec_and_test(atomic_t *v)
static __always_inline bool
atomic_inc_and_test(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_inc_and_test(v);
}
@ -553,6 +587,7 @@ atomic_inc_and_test(atomic_t *v)
static __always_inline bool
atomic_add_negative(int i, atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_add_negative(i, v);
}
@ -560,6 +595,7 @@ atomic_add_negative(int i, atomic_t *v)
static __always_inline int
atomic_fetch_add_unless(atomic_t *v, int a, int u)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_fetch_add_unless(v, a, u);
}
@ -567,6 +603,7 @@ atomic_fetch_add_unless(atomic_t *v, int a, int u)
static __always_inline bool
atomic_add_unless(atomic_t *v, int a, int u)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_add_unless(v, a, u);
}
@ -574,6 +611,7 @@ atomic_add_unless(atomic_t *v, int a, int u)
static __always_inline bool
atomic_inc_not_zero(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_inc_not_zero(v);
}
@ -581,6 +619,7 @@ atomic_inc_not_zero(atomic_t *v)
static __always_inline bool
atomic_inc_unless_negative(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_inc_unless_negative(v);
}
@ -588,6 +627,7 @@ atomic_inc_unless_negative(atomic_t *v)
static __always_inline bool
atomic_dec_unless_positive(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_dec_unless_positive(v);
}
@ -595,6 +635,7 @@ atomic_dec_unless_positive(atomic_t *v)
static __always_inline int
atomic_dec_if_positive(atomic_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_dec_if_positive(v);
}
@ -623,6 +664,7 @@ atomic64_set(atomic64_t *v, s64 i)
static __always_inline void
atomic64_set_release(atomic64_t *v, s64 i)
{
kcsan_release();
instrument_atomic_write(v, sizeof(*v));
arch_atomic64_set_release(v, i);
}
@ -637,6 +679,7 @@ atomic64_add(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_add_return(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_add_return(i, v);
}
@ -651,6 +694,7 @@ atomic64_add_return_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_add_return_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_add_return_release(i, v);
}
@ -665,6 +709,7 @@ atomic64_add_return_relaxed(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_add(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_add(i, v);
}
@ -679,6 +724,7 @@ atomic64_fetch_add_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_add_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_add_release(i, v);
}
@ -700,6 +746,7 @@ atomic64_sub(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_sub_return(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_sub_return(i, v);
}
@ -714,6 +761,7 @@ atomic64_sub_return_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_sub_return_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_sub_return_release(i, v);
}
@ -728,6 +776,7 @@ atomic64_sub_return_relaxed(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_sub(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_sub(i, v);
}
@ -742,6 +791,7 @@ atomic64_fetch_sub_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_sub_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_sub_release(i, v);
}
@ -763,6 +813,7 @@ atomic64_inc(atomic64_t *v)
static __always_inline s64
atomic64_inc_return(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_inc_return(v);
}
@ -777,6 +828,7 @@ atomic64_inc_return_acquire(atomic64_t *v)
static __always_inline s64
atomic64_inc_return_release(atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_inc_return_release(v);
}
@ -791,6 +843,7 @@ atomic64_inc_return_relaxed(atomic64_t *v)
static __always_inline s64
atomic64_fetch_inc(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_inc(v);
}
@ -805,6 +858,7 @@ atomic64_fetch_inc_acquire(atomic64_t *v)
static __always_inline s64
atomic64_fetch_inc_release(atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_inc_release(v);
}
@ -826,6 +880,7 @@ atomic64_dec(atomic64_t *v)
static __always_inline s64
atomic64_dec_return(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_dec_return(v);
}
@ -840,6 +895,7 @@ atomic64_dec_return_acquire(atomic64_t *v)
static __always_inline s64
atomic64_dec_return_release(atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_dec_return_release(v);
}
@ -854,6 +910,7 @@ atomic64_dec_return_relaxed(atomic64_t *v)
static __always_inline s64
atomic64_fetch_dec(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_dec(v);
}
@ -868,6 +925,7 @@ atomic64_fetch_dec_acquire(atomic64_t *v)
static __always_inline s64
atomic64_fetch_dec_release(atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_dec_release(v);
}
@ -889,6 +947,7 @@ atomic64_and(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_and(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_and(i, v);
}
@ -903,6 +962,7 @@ atomic64_fetch_and_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_and_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_and_release(i, v);
}
@ -924,6 +984,7 @@ atomic64_andnot(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_andnot(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_andnot(i, v);
}
@ -938,6 +999,7 @@ atomic64_fetch_andnot_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_andnot_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_andnot_release(i, v);
}
@ -959,6 +1021,7 @@ atomic64_or(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_or(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_or(i, v);
}
@ -973,6 +1036,7 @@ atomic64_fetch_or_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_or_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_or_release(i, v);
}
@ -994,6 +1058,7 @@ atomic64_xor(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_xor(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_xor(i, v);
}
@ -1008,6 +1073,7 @@ atomic64_fetch_xor_acquire(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_xor_release(s64 i, atomic64_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_xor_release(i, v);
}
@ -1022,6 +1088,7 @@ atomic64_fetch_xor_relaxed(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_xchg(atomic64_t *v, s64 i)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_xchg(v, i);
}
@ -1036,6 +1103,7 @@ atomic64_xchg_acquire(atomic64_t *v, s64 i)
static __always_inline s64
atomic64_xchg_release(atomic64_t *v, s64 i)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_xchg_release(v, i);
}
@ -1050,6 +1118,7 @@ atomic64_xchg_relaxed(atomic64_t *v, s64 i)
static __always_inline s64
atomic64_cmpxchg(atomic64_t *v, s64 old, s64 new)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_cmpxchg(v, old, new);
}
@ -1064,6 +1133,7 @@ atomic64_cmpxchg_acquire(atomic64_t *v, s64 old, s64 new)
static __always_inline s64
atomic64_cmpxchg_release(atomic64_t *v, s64 old, s64 new)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_cmpxchg_release(v, old, new);
}
@ -1078,6 +1148,7 @@ atomic64_cmpxchg_relaxed(atomic64_t *v, s64 old, s64 new)
static __always_inline bool
atomic64_try_cmpxchg(atomic64_t *v, s64 *old, s64 new)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
instrument_atomic_read_write(old, sizeof(*old));
return arch_atomic64_try_cmpxchg(v, old, new);
@ -1094,6 +1165,7 @@ atomic64_try_cmpxchg_acquire(atomic64_t *v, s64 *old, s64 new)
static __always_inline bool
atomic64_try_cmpxchg_release(atomic64_t *v, s64 *old, s64 new)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
instrument_atomic_read_write(old, sizeof(*old));
return arch_atomic64_try_cmpxchg_release(v, old, new);
@ -1110,6 +1182,7 @@ atomic64_try_cmpxchg_relaxed(atomic64_t *v, s64 *old, s64 new)
static __always_inline bool
atomic64_sub_and_test(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_sub_and_test(i, v);
}
@ -1117,6 +1190,7 @@ atomic64_sub_and_test(s64 i, atomic64_t *v)
static __always_inline bool
atomic64_dec_and_test(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_dec_and_test(v);
}
@ -1124,6 +1198,7 @@ atomic64_dec_and_test(atomic64_t *v)
static __always_inline bool
atomic64_inc_and_test(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_inc_and_test(v);
}
@ -1131,6 +1206,7 @@ atomic64_inc_and_test(atomic64_t *v)
static __always_inline bool
atomic64_add_negative(s64 i, atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_add_negative(i, v);
}
@ -1138,6 +1214,7 @@ atomic64_add_negative(s64 i, atomic64_t *v)
static __always_inline s64
atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_fetch_add_unless(v, a, u);
}
@ -1145,6 +1222,7 @@ atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
static __always_inline bool
atomic64_add_unless(atomic64_t *v, s64 a, s64 u)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_add_unless(v, a, u);
}
@ -1152,6 +1230,7 @@ atomic64_add_unless(atomic64_t *v, s64 a, s64 u)
static __always_inline bool
atomic64_inc_not_zero(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_inc_not_zero(v);
}
@ -1159,6 +1238,7 @@ atomic64_inc_not_zero(atomic64_t *v)
static __always_inline bool
atomic64_inc_unless_negative(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_inc_unless_negative(v);
}
@ -1166,6 +1246,7 @@ atomic64_inc_unless_negative(atomic64_t *v)
static __always_inline bool
atomic64_dec_unless_positive(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_dec_unless_positive(v);
}
@ -1173,6 +1254,7 @@ atomic64_dec_unless_positive(atomic64_t *v)
static __always_inline s64
atomic64_dec_if_positive(atomic64_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic64_dec_if_positive(v);
}
@ -1201,6 +1283,7 @@ atomic_long_set(atomic_long_t *v, long i)
static __always_inline void
atomic_long_set_release(atomic_long_t *v, long i)
{
kcsan_release();
instrument_atomic_write(v, sizeof(*v));
arch_atomic_long_set_release(v, i);
}
@ -1215,6 +1298,7 @@ atomic_long_add(long i, atomic_long_t *v)
static __always_inline long
atomic_long_add_return(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_add_return(i, v);
}
@ -1229,6 +1313,7 @@ atomic_long_add_return_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_add_return_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_add_return_release(i, v);
}
@ -1243,6 +1328,7 @@ atomic_long_add_return_relaxed(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_add(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_add(i, v);
}
@ -1257,6 +1343,7 @@ atomic_long_fetch_add_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_add_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_add_release(i, v);
}
@ -1278,6 +1365,7 @@ atomic_long_sub(long i, atomic_long_t *v)
static __always_inline long
atomic_long_sub_return(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_sub_return(i, v);
}
@ -1292,6 +1380,7 @@ atomic_long_sub_return_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_sub_return_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_sub_return_release(i, v);
}
@ -1306,6 +1395,7 @@ atomic_long_sub_return_relaxed(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_sub(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_sub(i, v);
}
@ -1320,6 +1410,7 @@ atomic_long_fetch_sub_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_sub_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_sub_release(i, v);
}
@ -1341,6 +1432,7 @@ atomic_long_inc(atomic_long_t *v)
static __always_inline long
atomic_long_inc_return(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_inc_return(v);
}
@ -1355,6 +1447,7 @@ atomic_long_inc_return_acquire(atomic_long_t *v)
static __always_inline long
atomic_long_inc_return_release(atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_inc_return_release(v);
}
@ -1369,6 +1462,7 @@ atomic_long_inc_return_relaxed(atomic_long_t *v)
static __always_inline long
atomic_long_fetch_inc(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_inc(v);
}
@ -1383,6 +1477,7 @@ atomic_long_fetch_inc_acquire(atomic_long_t *v)
static __always_inline long
atomic_long_fetch_inc_release(atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_inc_release(v);
}
@ -1404,6 +1499,7 @@ atomic_long_dec(atomic_long_t *v)
static __always_inline long
atomic_long_dec_return(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_dec_return(v);
}
@ -1418,6 +1514,7 @@ atomic_long_dec_return_acquire(atomic_long_t *v)
static __always_inline long
atomic_long_dec_return_release(atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_dec_return_release(v);
}
@ -1432,6 +1529,7 @@ atomic_long_dec_return_relaxed(atomic_long_t *v)
static __always_inline long
atomic_long_fetch_dec(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_dec(v);
}
@ -1446,6 +1544,7 @@ atomic_long_fetch_dec_acquire(atomic_long_t *v)
static __always_inline long
atomic_long_fetch_dec_release(atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_dec_release(v);
}
@ -1467,6 +1566,7 @@ atomic_long_and(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_and(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_and(i, v);
}
@ -1481,6 +1581,7 @@ atomic_long_fetch_and_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_and_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_and_release(i, v);
}
@ -1502,6 +1603,7 @@ atomic_long_andnot(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_andnot(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_andnot(i, v);
}
@ -1516,6 +1618,7 @@ atomic_long_fetch_andnot_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_andnot_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_andnot_release(i, v);
}
@ -1537,6 +1640,7 @@ atomic_long_or(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_or(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_or(i, v);
}
@ -1551,6 +1655,7 @@ atomic_long_fetch_or_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_or_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_or_release(i, v);
}
@ -1572,6 +1677,7 @@ atomic_long_xor(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_xor(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_xor(i, v);
}
@ -1586,6 +1692,7 @@ atomic_long_fetch_xor_acquire(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_xor_release(long i, atomic_long_t *v)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_xor_release(i, v);
}
@ -1600,6 +1707,7 @@ atomic_long_fetch_xor_relaxed(long i, atomic_long_t *v)
static __always_inline long
atomic_long_xchg(atomic_long_t *v, long i)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_xchg(v, i);
}
@ -1614,6 +1722,7 @@ atomic_long_xchg_acquire(atomic_long_t *v, long i)
static __always_inline long
atomic_long_xchg_release(atomic_long_t *v, long i)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_xchg_release(v, i);
}
@ -1628,6 +1737,7 @@ atomic_long_xchg_relaxed(atomic_long_t *v, long i)
static __always_inline long
atomic_long_cmpxchg(atomic_long_t *v, long old, long new)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_cmpxchg(v, old, new);
}
@ -1642,6 +1752,7 @@ atomic_long_cmpxchg_acquire(atomic_long_t *v, long old, long new)
static __always_inline long
atomic_long_cmpxchg_release(atomic_long_t *v, long old, long new)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_cmpxchg_release(v, old, new);
}
@ -1656,6 +1767,7 @@ atomic_long_cmpxchg_relaxed(atomic_long_t *v, long old, long new)
static __always_inline bool
atomic_long_try_cmpxchg(atomic_long_t *v, long *old, long new)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
instrument_atomic_read_write(old, sizeof(*old));
return arch_atomic_long_try_cmpxchg(v, old, new);
@ -1672,6 +1784,7 @@ atomic_long_try_cmpxchg_acquire(atomic_long_t *v, long *old, long new)
static __always_inline bool
atomic_long_try_cmpxchg_release(atomic_long_t *v, long *old, long new)
{
kcsan_release();
instrument_atomic_read_write(v, sizeof(*v));
instrument_atomic_read_write(old, sizeof(*old));
return arch_atomic_long_try_cmpxchg_release(v, old, new);
@ -1688,6 +1801,7 @@ atomic_long_try_cmpxchg_relaxed(atomic_long_t *v, long *old, long new)
static __always_inline bool
atomic_long_sub_and_test(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_sub_and_test(i, v);
}
@ -1695,6 +1809,7 @@ atomic_long_sub_and_test(long i, atomic_long_t *v)
static __always_inline bool
atomic_long_dec_and_test(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_dec_and_test(v);
}
@ -1702,6 +1817,7 @@ atomic_long_dec_and_test(atomic_long_t *v)
static __always_inline bool
atomic_long_inc_and_test(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_inc_and_test(v);
}
@ -1709,6 +1825,7 @@ atomic_long_inc_and_test(atomic_long_t *v)
static __always_inline bool
atomic_long_add_negative(long i, atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_add_negative(i, v);
}
@ -1716,6 +1833,7 @@ atomic_long_add_negative(long i, atomic_long_t *v)
static __always_inline long
atomic_long_fetch_add_unless(atomic_long_t *v, long a, long u)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_fetch_add_unless(v, a, u);
}
@ -1723,6 +1841,7 @@ atomic_long_fetch_add_unless(atomic_long_t *v, long a, long u)
static __always_inline bool
atomic_long_add_unless(atomic_long_t *v, long a, long u)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_add_unless(v, a, u);
}
@ -1730,6 +1849,7 @@ atomic_long_add_unless(atomic_long_t *v, long a, long u)
static __always_inline bool
atomic_long_inc_not_zero(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_inc_not_zero(v);
}
@ -1737,6 +1857,7 @@ atomic_long_inc_not_zero(atomic_long_t *v)
static __always_inline bool
atomic_long_inc_unless_negative(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_inc_unless_negative(v);
}
@ -1744,6 +1865,7 @@ atomic_long_inc_unless_negative(atomic_long_t *v)
static __always_inline bool
atomic_long_dec_unless_positive(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_dec_unless_positive(v);
}
@ -1751,6 +1873,7 @@ atomic_long_dec_unless_positive(atomic_long_t *v)
static __always_inline long
atomic_long_dec_if_positive(atomic_long_t *v)
{
kcsan_mb();
instrument_atomic_read_write(v, sizeof(*v));
return arch_atomic_long_dec_if_positive(v);
}
@ -1758,6 +1881,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define xchg(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_mb(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_xchg(__ai_ptr, __VA_ARGS__); \
})
@ -1772,6 +1896,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define xchg_release(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_release(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_xchg_release(__ai_ptr, __VA_ARGS__); \
})
@ -1786,6 +1911,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define cmpxchg(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_mb(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_cmpxchg(__ai_ptr, __VA_ARGS__); \
})
@ -1800,6 +1926,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define cmpxchg_release(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_release(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_cmpxchg_release(__ai_ptr, __VA_ARGS__); \
})
@ -1814,6 +1941,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define cmpxchg64(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_mb(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_cmpxchg64(__ai_ptr, __VA_ARGS__); \
})
@ -1828,6 +1956,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define cmpxchg64_release(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_release(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_cmpxchg64_release(__ai_ptr, __VA_ARGS__); \
})
@ -1843,6 +1972,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
({ \
typeof(ptr) __ai_ptr = (ptr); \
typeof(oldp) __ai_oldp = (oldp); \
kcsan_mb(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
arch_try_cmpxchg(__ai_ptr, __ai_oldp, __VA_ARGS__); \
@ -1861,6 +1991,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
({ \
typeof(ptr) __ai_ptr = (ptr); \
typeof(oldp) __ai_oldp = (oldp); \
kcsan_release(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
arch_try_cmpxchg_release(__ai_ptr, __ai_oldp, __VA_ARGS__); \
@ -1892,6 +2023,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define sync_cmpxchg(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_mb(); \
instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
arch_sync_cmpxchg(__ai_ptr, __VA_ARGS__); \
})
@ -1899,6 +2031,7 @@ atomic_long_dec_if_positive(atomic_long_t *v)
#define cmpxchg_double(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
kcsan_mb(); \
instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
arch_cmpxchg_double(__ai_ptr, __VA_ARGS__); \
})
@ -1912,4 +2045,4 @@ atomic_long_dec_if_positive(atomic_long_t *v)
})
#endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
// 2a9553f0a9d5619f19151092df5cabbbf16ce835
// 87c974b93032afd42143613434d1a7788fa598f9

18
include/linux/compiler_attributes.h
View file

@ -308,6 +308,24 @@
# define __compiletime_warning(msg)
#endif
/*
* Optional: only supported since clang >= 14.0
*
* clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation
*
* disable_sanitizer_instrumentation is not always similar to
* no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers
* insert code into functions to prevent false positives. Unlike that,
* disable_sanitizer_instrumentation prevents all kinds of instrumentation to
* functions with the attribute.
*/
#if __has_attribute(disable_sanitizer_instrumentation)
# define __disable_sanitizer_instrumentation \
__attribute__((disable_sanitizer_instrumentation))
#else
# define __disable_sanitizer_instrumentation
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute

13
include/linux/compiler_types.h
View file

@ -198,9 +198,20 @@ struct ftrace_likely_data {
# define __no_kasan_or_inline __always_inline
#endif
#define __no_kcsan __no_sanitize_thread
#ifdef __SANITIZE_THREAD__
/*
* Clang still emits instrumentation for __tsan_func_{entry,exit}() and builtin
* atomics even with __no_sanitize_thread (to avoid false positives in userspace
* ThreadSanitizer). The kernel's requirements are stricter and we really do not
* want any instrumentation with __no_kcsan.
*
* Therefore we add __disable_sanitizer_instrumentation where available to
* disable all instrumentation. See Kconfig.kcsan where this is mandatory.
*/
# define __no_kcsan __no_sanitize_thread __disable_sanitizer_instrumentation
# define __no_sanitize_or_inline __no_kcsan notrace __maybe_unused
#else
# define __no_kcsan
#endif
#ifndef __no_sanitize_or_inline

83
include/linux/kcsan-checks.h
View file

@ -36,6 +36,36 @@
*/
void __kcsan_check_access(const volatile void *ptr, size_t size, int type);
/*
* See definition of __tsan_atomic_signal_fence() in kernel/kcsan/core.c.
* Note: The mappings are arbitrary, and do not reflect any real mappings of C11
* memory orders to the LKMM memory orders and vice-versa!
*/
#define __KCSAN_BARRIER_TO_SIGNAL_FENCE_mb __ATOMIC_SEQ_CST
#define __KCSAN_BARRIER_TO_SIGNAL_FENCE_wmb __ATOMIC_ACQ_REL
#define __KCSAN_BARRIER_TO_SIGNAL_FENCE_rmb __ATOMIC_ACQUIRE
#define __KCSAN_BARRIER_TO_SIGNAL_FENCE_release __ATOMIC_RELEASE
/**
* __kcsan_mb - full memory barrier instrumentation
*/
void __kcsan_mb(void);
/**
* __kcsan_wmb - write memory barrier instrumentation
*/
void __kcsan_wmb(void);
/**
* __kcsan_rmb - read memory barrier instrumentation
*/
void __kcsan_rmb(void);
/**
* __kcsan_release - release barrier instrumentation
*/
void __kcsan_release(void);
/**
* kcsan_disable_current - disable KCSAN for the current context
*
@ -99,7 +129,15 @@ void kcsan_set_access_mask(unsigned long mask);
/* Scoped access information. */
struct kcsan_scoped_access {
struct list_head list;
union {
struct list_head list; /* scoped_accesses list */
/*
* Not an entry in scoped_accesses list; stack depth from where
* the access was initialized.
*/
int stack_depth;
};
/* Access information. */
const volatile void *ptr;
size_t size;
@ -151,6 +189,10 @@ void kcsan_end_scoped_access(struct kcsan_scoped_access *sa);
static inline void __kcsan_check_access(const volatile void *ptr, size_t size,
int type) { }
static inline void __kcsan_mb(void) { }
static inline void __kcsan_wmb(void) { }
static inline void __kcsan_rmb(void) { }
static inline void __kcsan_release(void) { }
static inline void kcsan_disable_current(void) { }
static inline void kcsan_enable_current(void) { }
static inline void kcsan_enable_current_nowarn(void) { }
@ -183,12 +225,47 @@ static inline void kcsan_end_scoped_access(struct kcsan_scoped_access *sa) { }
*/
#define __kcsan_disable_current kcsan_disable_current
#define __kcsan_enable_current kcsan_enable_current_nowarn
#else
#else /* __SANITIZE_THREAD__ */
static inline void kcsan_check_access(const volatile void *ptr, size_t size,
int type) { }
static inline void __kcsan_enable_current(void) { }
static inline void __kcsan_disable_current(void) { }
#endif
#endif /* __SANITIZE_THREAD__ */
#if defined(CONFIG_KCSAN_WEAK_MEMORY) && defined(__SANITIZE_THREAD__)
/*
* Normal barrier instrumentation is not done via explicit calls, but by mapping
* to a repurposed __atomic_signal_fence(), which normally does not generate any
* real instructions, but is still intercepted by fsanitize=thread. This means,
* like any other compile-time instrumentation, barrier instrumentation can be
* disabled with the __no_kcsan function attribute.
*
* Also see definition of __tsan_atomic_signal_fence() in kernel/kcsan/core.c.
*
* These are all macros, like <asm/barrier.h>, since some architectures use them
* in non-static inline functions.
*/
#define __KCSAN_BARRIER_TO_SIGNAL_FENCE(name) \
do { \
barrier(); \
__atomic_signal_fence(__KCSAN_BARRIER_TO_SIGNAL_FENCE_##name); \
barrier(); \
} while (0)
#define kcsan_mb() __KCSAN_BARRIER_TO_SIGNAL_FENCE(mb)
#define kcsan_wmb() __KCSAN_BARRIER_TO_SIGNAL_FENCE(wmb)
#define kcsan_rmb() __KCSAN_BARRIER_TO_SIGNAL_FENCE(rmb)
#define kcsan_release() __KCSAN_BARRIER_TO_SIGNAL_FENCE(release)
#elif defined(CONFIG_KCSAN_WEAK_MEMORY) && defined(__KCSAN_INSTRUMENT_BARRIERS__)
#define kcsan_mb __kcsan_mb
#define kcsan_wmb __kcsan_wmb
#define kcsan_rmb __kcsan_rmb
#define kcsan_release __kcsan_release
#else /* CONFIG_KCSAN_WEAK_MEMORY && ... */
#define kcsan_mb() do { } while (0)
#define kcsan_wmb() do { } while (0)
#define kcsan_rmb() do { } while (0)
#define kcsan_release() do { } while (0)
#endif /* CONFIG_KCSAN_WEAK_MEMORY && ... */
/**
* __kcsan_check_read - check regular read access for races

11
include/linux/kcsan.h
View file

@ -21,6 +21,7 @@
*/
struct kcsan_ctx {
int disable_count; /* disable counter */
int disable_scoped; /* disable scoped access counter */
int atomic_next; /* number of following atomic ops */
/*
@ -48,8 +49,16 @@ struct kcsan_ctx {
*/
unsigned long access_mask;
/* List of scoped accesses. */
/* List of scoped accesses; likely to be empty. */
struct list_head scoped_accesses;
#ifdef CONFIG_KCSAN_WEAK_MEMORY
/*
* Scoped access for modeling access reordering to detect missing memory
* barriers; only keep 1 to keep fast-path complexity manageable.
*/
struct kcsan_scoped_access reorder_access;
#endif
};
/**

3
include/linux/sched.h
View file

@ -1339,6 +1339,9 @@ struct task_struct {
#ifdef CONFIG_TRACE_IRQFLAGS
struct irqtrace_events kcsan_save_irqtrace;
#endif
#ifdef CONFIG_KCSAN_WEAK_MEMORY
int kcsan_stack_depth;
#endif
#endif
#if IS_ENABLED(CONFIG_KUNIT)

2
include/linux/spinlock.h
View file

@ -171,7 +171,7 @@ do { \
* Architectures that can implement ACQUIRE better need to take care.
*/
#ifndef smp_mb__after_spinlock
#define smp_mb__after_spinlock() do { } while (0)
#define smp_mb__after_spinlock() kcsan_mb()
#endif
#ifdef CONFIG_DEBUG_SPINLOCK

5
init/init_task.c
View file

@ -182,11 +182,6 @@ struct task_struct init_task
#endif
#ifdef CONFIG_KCSAN
.kcsan_ctx = {
.disable_count = 0,
.atomic_next = 0,
.atomic_nest_count = 0,
.in_flat_atomic = false,
.access_mask = 0,
.scoped_accesses = {LIST_POISON1, NULL},
},
#endif

2
kernel/kcsan/Makefile
View file

@ -12,6 +12,8 @@ CFLAGS_core.o := $(call cc-option,-fno-conserve-stack) \
-fno-stack-protector -DDISABLE_BRANCH_PROFILING
obj-y := core.o debugfs.o report.o
KCSAN_INSTRUMENT_BARRIERS_selftest.o := y
obj-$(CONFIG_KCSAN_SELFTEST) += selftest.o
CFLAGS_kcsan_test.o := $(CFLAGS_KCSAN) -g -fno-omit-frame-pointer

347
kernel/kcsan/core.c
View file

@ -40,15 +40,17 @@ module_param_named(udelay_interrupt, kcsan_udelay_interrupt, uint, 0644);
module_param_named(skip_watch, kcsan_skip_watch, long, 0644);
module_param_named(interrupt_watcher, kcsan_interrupt_watcher, bool, 0444);
#ifdef CONFIG_KCSAN_WEAK_MEMORY
static bool kcsan_weak_memory = true;
module_param_named(weak_memory, kcsan_weak_memory, bool, 0644);
#else
#define kcsan_weak_memory false
#endif
bool kcsan_enabled;
/* Per-CPU kcsan_ctx for interrupts */
static DEFINE_PER_CPU(struct kcsan_ctx, kcsan_cpu_ctx) = {
.disable_count = 0,
.atomic_next = 0,
.atomic_nest_count = 0,
.in_flat_atomic = false,
.access_mask = 0,
.scoped_accesses = {LIST_POISON1, NULL},
};
@ -209,15 +211,17 @@ check_access(const volatile void *ptr, size_t size, int type, unsigned long ip);
static noinline void kcsan_check_scoped_accesses(void)
{
struct kcsan_ctx *ctx = get_ctx();
struct list_head *prev_save = ctx->scoped_accesses.prev;
struct kcsan_scoped_access *scoped_access;
ctx->scoped_accesses.prev = NULL; /* Avoid recursion. */
if (ctx->disable_scoped)
return;
ctx->disable_scoped++;
list_for_each_entry(scoped_access, &ctx->scoped_accesses, list) {
check_access(scoped_access->ptr, scoped_access->size,
scoped_access->type, scoped_access->ip);
}
ctx->scoped_accesses.prev = prev_save;
ctx->disable_scoped--;
}
/* Rules for generic atomic accesses. Called from fast-path. */
@ -325,6 +329,21 @@ static void delay_access(int type)
udelay(delay);
}
/*
* Reads the instrumented memory for value change detection; value change
* detection is currently done for accesses up to a size of 8 bytes.
*/
static __always_inline u64 read_instrumented_memory(const volatile void *ptr, size_t size)
{
switch (size) {
case 1: return READ_ONCE(*(const u8 *)ptr);
case 2: return READ_ONCE(*(const u16 *)ptr);
case 4: return READ_ONCE(*(const u32 *)ptr);
case 8: return READ_ONCE(*(const u64 *)ptr);
default: return 0; /* Ignore; we do not diff the values. */
}
}
void kcsan_save_irqtrace(struct task_struct *task)
{
#ifdef CONFIG_TRACE_IRQFLAGS
@ -339,6 +358,76 @@ void kcsan_restore_irqtrace(struct task_struct *task)
#endif
}
static __always_inline int get_kcsan_stack_depth(void)
{
#ifdef CONFIG_KCSAN_WEAK_MEMORY
return current->kcsan_stack_depth;
#else
BUILD_BUG();
return 0;
#endif
}
static __always_inline void add_kcsan_stack_depth(int val)
{
#ifdef CONFIG_KCSAN_WEAK_MEMORY
current->kcsan_stack_depth += val;
#else
BUILD_BUG();
#endif
}
static __always_inline struct kcsan_scoped_access *get_reorder_access(struct kcsan_ctx *ctx)
{
#ifdef CONFIG_KCSAN_WEAK_MEMORY
return ctx->disable_scoped ? NULL : &ctx->reorder_access;
#else
return NULL;
#endif
}
static __always_inline bool
find_reorder_access(struct kcsan_ctx *ctx, const volatile void *ptr, size_t size,
int type, unsigned long ip)
{
struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
if (!reorder_access)
return false;
/*
* Note: If accesses are repeated while reorder_access is identical,
* never matches the new access, because !(type & KCSAN_ACCESS_SCOPED).
*/
return reorder_access->ptr == ptr && reorder_access->size == size &&
reorder_access->type == type && reorder_access->ip == ip;
}
static inline void
set_reorder_access(struct kcsan_ctx *ctx, const volatile void *ptr, size_t size,
int type, unsigned long ip)
{
struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
if (!reorder_access || !kcsan_weak_memory)
return;
/*
* To avoid nested interrupts or scheduler (which share kcsan_ctx)
* reading an inconsistent reorder_access, ensure that the below has
* exclusive access to reorder_access by disallowing concurrent use.
*/
ctx->disable_scoped++;
barrier();
reorder_access->ptr = ptr;
reorder_access->size = size;
reorder_access->type = type | KCSAN_ACCESS_SCOPED;
reorder_access->ip = ip;
reorder_access->stack_depth = get_kcsan_stack_depth();
barrier();
ctx->disable_scoped--;
}
/*
* Pull everything together: check_access() below contains the performance
* critical operations; the fast-path (including check_access) functions should
@ -377,8 +466,10 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
* The access_mask check relies on value-change comparison. To avoid
* reporting a race where e.g. the writer set up the watchpoint, but the
* reader has access_mask!=0, we have to ignore the found watchpoint.
*
* reorder_access is never created from an access with access_mask set.
*/
if (ctx->access_mask)
if (ctx->access_mask && !find_reorder_access(ctx, ptr, size, type, ip))
return;
/*
@ -428,11 +519,13 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
const bool is_assert = (type & KCSAN_ACCESS_ASSERT) != 0;
atomic_long_t *watchpoint;
u64 old, new, diff;
unsigned long access_mask;
enum kcsan_value_change value_change = KCSAN_VALUE_CHANGE_MAYBE;
bool interrupt_watcher = kcsan_interrupt_watcher;
unsigned long ua_flags = user_access_save();
struct kcsan_ctx *ctx = get_ctx();
unsigned long access_mask = ctx->access_mask;
unsigned long irq_flags = 0;
bool is_reorder_access;
/*
* Always reset kcsan_skip counter in slow-path to avoid underflow; see
@ -455,13 +548,33 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
goto out;
}
/*
* The local CPU cannot observe reordering of its own accesses, and
* therefore we need to take care of 2 cases to avoid false positives:
*
* 1. Races of the reordered access with interrupts. To avoid, if
* the current access is reorder_access, disable interrupts.
* 2. Avoid races of scoped accesses from nested interrupts (below).
*/
is_reorder_access = find_reorder_access(ctx, ptr, size, type, ip);
if (is_reorder_access)
interrupt_watcher = false;
/*
* Avoid races of scoped accesses from nested interrupts (or scheduler).
* Assume setting up a watchpoint for a non-scoped (normal) access that
* also conflicts with a current scoped access. In a nested interrupt,
* which shares the context, it would check a conflicting scoped access.
* To avoid, disable scoped access checking.
*/
ctx->disable_scoped++;
/*
* Save and restore the IRQ state trace touched by KCSAN, since KCSAN's
* runtime is entered for every memory access, and potentially useful
* information is lost if dirtied by KCSAN.
*/
kcsan_save_irqtrace(current);
if (!kcsan_interrupt_watcher)
if (!interrupt_watcher)
local_irq_save(irq_flags);
watchpoint = insert_watchpoint((unsigned long)ptr, size, is_write);
@ -482,23 +595,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
* Read the current value, to later check and infer a race if the data
* was modified via a non-instrumented access, e.g. from a device.
*/
old = 0;
switch (size) {
case 1:
old = READ_ONCE(*(const u8 *)ptr);
break;
case 2:
old = READ_ONCE(*(const u16 *)ptr);
break;
case 4:
old = READ_ONCE(*(const u32 *)ptr);
break;
case 8:
old = READ_ONCE(*(const u64 *)ptr);
break;
default:
break; /* ignore; we do not diff the values */
}
old = is_reorder_access ? 0 : read_instrumented_memory(ptr, size);
/*
* Delay this thread, to increase probability of observing a racy
@ -510,23 +607,16 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
* Re-read value, and check if it is as expected; if not, we infer a
* racy access.
*/
access_mask = ctx->access_mask;
new = 0;
switch (size) {
case 1:
new = READ_ONCE(*(const u8 *)ptr);
break;
case 2:
new = READ_ONCE(*(const u16 *)ptr);
break;
case 4:
new = READ_ONCE(*(const u32 *)ptr);
break;
case 8:
new = READ_ONCE(*(const u64 *)ptr);
break;
default:
break; /* ignore; we do not diff the values */
if (!is_reorder_access) {
new = read_instrumented_memory(ptr, size);
} else {
/*
* Reordered accesses cannot be used for value change detection,
* because the memory location may no longer be accessible and
* could result in a fault.
*/
new = 0;
access_mask = 0;
}
diff = old ^ new;
@ -596,10 +686,20 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
*/
remove_watchpoint(watchpoint);
atomic_long_dec(&kcsan_counters[KCSAN_COUNTER_USED_WATCHPOINTS]);
out_unlock:
if (!kcsan_interrupt_watcher)
if (!interrupt_watcher)
local_irq_restore(irq_flags);
kcsan_restore_irqtrace(current);
ctx->disable_scoped--;
/*
* Reordered accesses cannot be used for value change detection,
* therefore never consider for reordering if access_mask is set.
* ASSERT_EXCLUSIVE are not real accesses, ignore them as well.
*/
if (!access_mask && !is_assert)
set_reorder_access(ctx, ptr, size, type, ip);
out:
user_access_restore(ua_flags);
}
@ -607,7 +707,6 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
static __always_inline void
check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
{
const bool is_write = (type & KCSAN_ACCESS_WRITE) != 0;
atomic_long_t *watchpoint;
long encoded_watchpoint;
@ -618,12 +717,14 @@ check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
if (unlikely(size == 0))
return;
again:
/*
* Avoid user_access_save in fast-path: find_watchpoint is safe without
* user_access_save, as the address that ptr points to is only used to
* check if a watchpoint exists; ptr is never dereferenced.
*/
watchpoint = find_watchpoint((unsigned long)ptr, size, !is_write,
watchpoint = find_watchpoint((unsigned long)ptr, size,
!(type & KCSAN_ACCESS_WRITE),
&encoded_watchpoint);
/*
* It is safe to check kcsan_is_enabled() after find_watchpoint in the
@ -637,9 +738,42 @@ check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
else {
struct kcsan_ctx *ctx = get_ctx(); /* Call only once in fast-path. */
if (unlikely(should_watch(ctx, ptr, size, type)))
if (unlikely(should_watch(ctx, ptr, size, type))) {
kcsan_setup_watchpoint(ptr, size, type, ip);
else if (unlikely(ctx->scoped_accesses.prev))
return;
}
if (!(type & KCSAN_ACCESS_SCOPED)) {
struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
if (reorder_access) {
/*
* reorder_access check: simulates reordering of
* the access after subsequent operations.
*/
ptr = reorder_access->ptr;
type = reorder_access->type;
ip = reorder_access->ip;
/*
* Upon a nested interrupt, this context's
* reorder_access can be modified (shared ctx).
* We know that upon return, reorder_access is
* always invalidated by setting size to 0 via
* __tsan_func_exit(). Therefore we must read
* and check size after the other fields.
*/
barrier();
size = READ_ONCE(reorder_access->size);
if (size)
goto again;
}
}
/*
* Always checked last, right before returning from runtime;
* if reorder_access is valid, checked after it was checked.
*/
if (unlikely(ctx->scoped_accesses.prev))
kcsan_check_scoped_accesses();
}
}
@ -814,6 +948,22 @@ void __kcsan_check_access(const volatile void *ptr, size_t size, int type)
}
EXPORT_SYMBOL(__kcsan_check_access);
#define DEFINE_MEMORY_BARRIER(name, order_before_cond) \
void __kcsan_##name(void) \
{ \
struct kcsan_scoped_access *sa = get_reorder_access(get_ctx()); \
if (!sa) \
return; \
if (order_before_cond) \
sa->size = 0; \
} \
EXPORT_SYMBOL(__kcsan_##name)
DEFINE_MEMORY_BARRIER(mb, true);
DEFINE_MEMORY_BARRIER(wmb, sa->type & (KCSAN_ACCESS_WRITE | KCSAN_ACCESS_COMPOUND));
DEFINE_MEMORY_BARRIER(rmb, !(sa->type & KCSAN_ACCESS_WRITE) || (sa->type & KCSAN_ACCESS_COMPOUND));
DEFINE_MEMORY_BARRIER(release, true);
/*
* KCSAN uses the same instrumentation that is emitted by supported compilers
* for ThreadSanitizer (TSAN).
@ -926,19 +1076,56 @@ DEFINE_TSAN_VOLATILE_READ_WRITE(8);
DEFINE_TSAN_VOLATILE_READ_WRITE(16);
/*
* The below are not required by KCSAN, but can still be emitted by the
* compiler.
* Function entry and exit are used to determine the validty of reorder_access.
* Reordering of the access ends at the end of the function scope where the
* access happened. This is done for two reasons:
*
* 1. Artificially limits the scope where missing barriers are detected.
* This minimizes false positives due to uninstrumented functions that
* contain the required barriers but were missed.
*
* 2. Simplifies generating the stack trace of the access.
*/
void __tsan_func_entry(void *call_pc);
void __tsan_func_entry(void *call_pc)
noinline void __tsan_func_entry(void *call_pc)
{
if (!IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
return;
add_kcsan_stack_depth(1);
}
EXPORT_SYMBOL(__tsan_func_entry);
void __tsan_func_exit(void);
void __tsan_func_exit(void)
noinline void __tsan_func_exit(void)
{
struct kcsan_scoped_access *reorder_access;
if (!IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
return;
reorder_access = get_reorder_access(get_ctx());
if (!reorder_access)
goto out;
if (get_kcsan_stack_depth() <= reorder_access->stack_depth) {
/*
* Access check to catch cases where write without a barrier
* (supposed release) was last access in function: because
* instrumentation is inserted before the real access, a data
* race due to the write giving up a c-s would only be caught if
* we do the conflicting access after.
*/
check_access(reorder_access->ptr, reorder_access->size,
reorder_access->type, reorder_access->ip);
reorder_access->size = 0;
reorder_access->stack_depth = INT_MIN;
}
out:
add_kcsan_stack_depth(-1);
}
EXPORT_SYMBOL(__tsan_func_exit);
void __tsan_init(void);
void __tsan_init(void)
{
@ -961,10 +1148,19 @@ EXPORT_SYMBOL(__tsan_init);
* functions, whose job is to also execute the operation itself.
*/
static __always_inline void kcsan_atomic_builtin_memorder(int memorder)
{
if (memorder == __ATOMIC_RELEASE ||
memorder == __ATOMIC_SEQ_CST ||
memorder == __ATOMIC_ACQ_REL)
__kcsan_release();
}
#define DEFINE_TSAN_ATOMIC_LOAD_STORE(bits) \
u##bits __tsan_atomic##bits##_load(const u##bits *ptr, int memorder); \
u##bits __tsan_atomic##bits##_load(const u##bits *ptr, int memorder) \
{ \
kcsan_atomic_builtin_memorder(memorder); \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \
@ -974,6 +1170,7 @@ EXPORT_SYMBOL(__tsan_init);
void __tsan_atomic##bits##_store(u##bits *ptr, u##bits v, int memorder); \
void __tsan_atomic##bits##_store(u##bits *ptr, u##bits v, int memorder) \
{ \
kcsan_atomic_builtin_memorder(memorder); \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC, _RET_IP_); \
@ -986,6 +1183,7 @@ EXPORT_SYMBOL(__tsan_init);
u##bits __tsan_atomic##bits##_##op(u##bits *ptr, u##bits v, int memorder); \
u##bits __tsan_atomic##bits##_##op(u##bits *ptr, u##bits v, int memorder) \
{ \
kcsan_atomic_builtin_memorder(memorder); \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
@ -1018,6 +1216,7 @@ EXPORT_SYMBOL(__tsan_init);
int __tsan_atomic##bits##_compare_exchange_##strength(u##bits *ptr, u##bits *exp, \
u##bits val, int mo, int fail_mo) \
{ \
kcsan_atomic_builtin_memorder(mo); \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
@ -1033,6 +1232,7 @@ EXPORT_SYMBOL(__tsan_init);
u##bits __tsan_atomic##bits##_compare_exchange_val(u##bits *ptr, u##bits exp, u##bits val, \
int mo, int fail_mo) \
{ \
kcsan_atomic_builtin_memorder(mo); \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
@ -1064,10 +1264,47 @@ DEFINE_TSAN_ATOMIC_OPS(64);
void __tsan_atomic_thread_fence(int memorder);
void __tsan_atomic_thread_fence(int memorder)
{
kcsan_atomic_builtin_memorder(memorder);
__atomic_thread_fence(memorder);
}
EXPORT_SYMBOL(__tsan_atomic_thread_fence);
/*
* In instrumented files, we emit instrumentation for barriers by mapping the
* kernel barriers to an __atomic_signal_fence(), which is interpreted specially
* and otherwise has no relation to a real __atomic_signal_fence(). No known
* kernel code uses __atomic_signal_fence().
*
* Since fsanitize=thread instrumentation handles __atomic_signal_fence(), which
* are turned into calls to __tsan_atomic_signal_fence(), such instrumentation
* can be disabled via the __no_kcsan function attribute (vs. an explicit call
* which could not). When __no_kcsan is requested, __atomic_signal_fence()
* generates no code.
*
* Note: The result of using __atomic_signal_fence() with KCSAN enabled is
* potentially limiting the compiler's ability to reorder operations; however,
* if barriers were instrumented with explicit calls (without LTO), the compiler
* couldn't optimize much anyway. The result of a hypothetical architecture
* using __atomic_signal_fence() in normal code would be KCSAN false negatives.
*/
void __tsan_atomic_signal_fence(int memorder);
void __tsan_atomic_signal_fence(int memorder) { }
noinline void __tsan_atomic_signal_fence(int memorder)
{
switch (memorder) {
case __KCSAN_BARRIER_TO_SIGNAL_FENCE_mb:
__kcsan_mb();
break;
case __KCSAN_BARRIER_TO_SIGNAL_FENCE_wmb:
__kcsan_wmb();
break;
case __KCSAN_BARRIER_TO_SIGNAL_FENCE_rmb:
__kcsan_rmb();
break;
case __KCSAN_BARRIER_TO_SIGNAL_FENCE_release:
__kcsan_release();
break;
default:
break;
}
}
EXPORT_SYMBOL(__tsan_atomic_signal_fence);

426
kernel/kcsan/kcsan_test.c
View file

@ -16,9 +16,12 @@
#define pr_fmt(fmt) "kcsan_test: " fmt
#include <kunit/test.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/jiffies.h>
#include <linux/kcsan-checks.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/seqlock.h>
#include <linux/spinlock.h>
@ -151,7 +154,7 @@ struct expect_report {
/* Check observed report matches information in @r. */
__no_kcsan
static bool report_matches(const struct expect_report *r)
static bool __report_matches(const struct expect_report *r)
{
const bool is_assert = (r->access[0].type | r->access[1].type) & KCSAN_ACCESS_ASSERT;
bool ret = false;
@ -213,9 +216,9 @@ static bool report_matches(const struct expect_report *r)
const bool is_atomic = (ty & KCSAN_ACCESS_ATOMIC);
const bool is_scoped = (ty & KCSAN_ACCESS_SCOPED);
const char *const access_type_aux =
(is_atomic && is_scoped) ? " (marked, scoped)"
(is_atomic && is_scoped) ? " (marked, reordered)"
: (is_atomic ? " (marked)"
: (is_scoped ? " (scoped)" : ""));
: (is_scoped ? " (reordered)" : ""));
if (i == 1) {
/* Access 2 */
@ -253,6 +256,40 @@ static bool report_matches(const struct expect_report *r)
return ret;
}
static __always_inline const struct expect_report *
__report_set_scoped(struct expect_report *r, int accesses)
{
BUILD_BUG_ON(accesses > 3);
if (accesses & 1)
r->access[0].type |= KCSAN_ACCESS_SCOPED;
else
r->access[0].type &= ~KCSAN_ACCESS_SCOPED;
if (accesses & 2)
r->access[1].type |= KCSAN_ACCESS_SCOPED;
else
r->access[1].type &= ~KCSAN_ACCESS_SCOPED;
return r;
}
__no_kcsan
static bool report_matches_any_reordered(struct expect_report *r)
{
return __report_matches(__report_set_scoped(r, 0)) ||
__report_matches(__report_set_scoped(r, 1)) ||
__report_matches(__report_set_scoped(r, 2)) ||
__report_matches(__report_set_scoped(r, 3));
}
#ifdef CONFIG_KCSAN_WEAK_MEMORY
/* Due to reordering accesses, any access may appear as "(reordered)". */
#define report_matches report_matches_any_reordered
#else
#define report_matches __report_matches
#endif
/* ===== Test kernels ===== */
static long test_sink;
@ -263,6 +300,8 @@ static struct {
long val[8];
} test_struct;
static DEFINE_SEQLOCK(test_seqlock);
static DEFINE_SPINLOCK(test_spinlock);
static DEFINE_MUTEX(test_mutex);
/*
* Helper to avoid compiler optimizing out reads, and to generate source values
@ -271,6 +310,16 @@ static DEFINE_SEQLOCK(test_seqlock);
__no_kcsan
static noinline void sink_value(long v) { WRITE_ONCE(test_sink, v); }
/*
* Generates a delay and some accesses that enter the runtime but do not produce
* data races.
*/
static noinline void test_delay(int iter)
{
while (iter--)
sink_value(READ_ONCE(test_sink));
}
static noinline void test_kernel_read(void) { sink_value(test_var); }
static noinline void test_kernel_write(void)
@ -432,19 +481,239 @@ static noinline void test_kernel_xor_1bit(void)
kcsan_nestable_atomic_end();
}
#define TEST_KERNEL_LOCKED(name, acquire, release) \
static noinline void test_kernel_##name(void) \
{ \
long *flag = &test_struct.val[0]; \
long v = 0; \
if (!(acquire)) \
return; \
while (v++ < 100) { \
test_var++; \
barrier(); \
} \
release; \
test_delay(10); \
}
TEST_KERNEL_LOCKED(with_memorder,
cmpxchg_acquire(flag, 0, 1) == 0,
smp_store_release(flag, 0));
TEST_KERNEL_LOCKED(wrong_memorder,
cmpxchg_relaxed(flag, 0, 1) == 0,
WRITE_ONCE(*flag, 0));
TEST_KERNEL_LOCKED(atomic_builtin_with_memorder,
__atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED),
__atomic_store_n(flag, 0, __ATOMIC_RELEASE));
TEST_KERNEL_LOCKED(atomic_builtin_wrong_memorder,
__atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED),
__atomic_store_n(flag, 0, __ATOMIC_RELAXED));
/* ===== Test cases ===== */
/*
* Tests that various barriers have the expected effect on internal state. Not
* exhaustive on atomic_t operations. Unlike the selftest, also checks for
* too-strict barrier instrumentation; these can be tolerated, because it does
* not cause false positives, but at least we should be aware of such cases.
*/
static void test_barrier_nothreads(struct kunit *test)
{
#ifdef CONFIG_KCSAN_WEAK_MEMORY
struct kcsan_scoped_access *reorder_access = &current->kcsan_ctx.reorder_access;
#else
struct kcsan_scoped_access *reorder_access = NULL;
#endif
arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;
atomic_t dummy;
KCSAN_TEST_REQUIRES(test, reorder_access != NULL);
KCSAN_TEST_REQUIRES(test, IS_ENABLED(CONFIG_SMP));
#define __KCSAN_EXPECT_BARRIER(access_type, barrier, order_before, name) \
do { \
reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED; \
reorder_access->size = sizeof(test_var); \
barrier; \
KUNIT_EXPECT_EQ_MSG(test, reorder_access->size, \
order_before ? 0 : sizeof(test_var), \
"improperly instrumented type=(" #access_type "): " name); \
} while (0)
#define KCSAN_EXPECT_READ_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(0, b, o, #b)
#define KCSAN_EXPECT_WRITE_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_WRITE, b, o, #b)
#define KCSAN_EXPECT_RW_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE, b, o, #b)
/*
* Lockdep initialization can strengthen certain locking operations due
* to calling into instrumented files; "warm up" our locks.
*/
spin_lock(&test_spinlock);
spin_unlock(&test_spinlock);
mutex_lock(&test_mutex);
mutex_unlock(&test_mutex);
/* Force creating a valid entry in reorder_access first. */
test_var = 0;
while (test_var++ < 1000000 && reorder_access->size != sizeof(test_var))
__kcsan_check_read(&test_var, sizeof(test_var));
KUNIT_ASSERT_EQ(test, reorder_access->size, sizeof(test_var));
kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */
KCSAN_EXPECT_READ_BARRIER(mb(), true);
KCSAN_EXPECT_READ_BARRIER(wmb(), false);
KCSAN_EXPECT_READ_BARRIER(rmb(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb(), true);
KCSAN_EXPECT_READ_BARRIER(smp_wmb(), false);
KCSAN_EXPECT_READ_BARRIER(smp_rmb(), true);
KCSAN_EXPECT_READ_BARRIER(dma_wmb(), false);
KCSAN_EXPECT_READ_BARRIER(dma_rmb(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb__before_atomic(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb__after_atomic(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb__after_spinlock(), true);
KCSAN_EXPECT_READ_BARRIER(smp_store_mb(test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(smp_load_acquire(&test_var), false);
KCSAN_EXPECT_READ_BARRIER(smp_store_release(&test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(xchg(&test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(xchg_release(&test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(xchg_relaxed(&test_var, 0), false);
KCSAN_EXPECT_READ_BARRIER(cmpxchg(&test_var, 0, 0), true);
KCSAN_EXPECT_READ_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
KCSAN_EXPECT_READ_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_read_acquire(&dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_set(&dummy, 0), false);
KCSAN_EXPECT_READ_BARRIER(atomic_set_release(&dummy, 0), true);
KCSAN_EXPECT_READ_BARRIER(atomic_add(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return_acquire(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return_release(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_release(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(test_and_set_bit(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(test_and_clear_bit(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(test_and_change_bit(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(__clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(arch_spin_lock(&arch_spinlock), false);
KCSAN_EXPECT_READ_BARRIER(arch_spin_unlock(&arch_spinlock), true);
KCSAN_EXPECT_READ_BARRIER(spin_lock(&test_spinlock), false);
KCSAN_EXPECT_READ_BARRIER(spin_unlock(&test_spinlock), true);
KCSAN_EXPECT_READ_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_READ_BARRIER(mutex_unlock(&test_mutex), true);
KCSAN_EXPECT_WRITE_BARRIER(mb(), true);
KCSAN_EXPECT_WRITE_BARRIER(wmb(), true);
KCSAN_EXPECT_WRITE_BARRIER(rmb(), false);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_wmb(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_rmb(), false);
KCSAN_EXPECT_WRITE_BARRIER(dma_wmb(), true);
KCSAN_EXPECT_WRITE_BARRIER(dma_rmb(), false);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb__before_atomic(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_atomic(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_spinlock(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_store_mb(test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_load_acquire(&test_var), false);
KCSAN_EXPECT_WRITE_BARRIER(smp_store_release(&test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(xchg(&test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(xchg_release(&test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(xchg_relaxed(&test_var, 0), false);
KCSAN_EXPECT_WRITE_BARRIER(cmpxchg(&test_var, 0, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_read(&dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_read_acquire(&dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_set(&dummy, 0), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_set_release(&dummy, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_acquire(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_release(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(test_and_set_bit(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(test_and_clear_bit(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(test_and_change_bit(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(__clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(arch_spin_lock(&arch_spinlock), false);
KCSAN_EXPECT_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock), true);
KCSAN_EXPECT_WRITE_BARRIER(spin_lock(&test_spinlock), false);
KCSAN_EXPECT_WRITE_BARRIER(spin_unlock(&test_spinlock), true);
KCSAN_EXPECT_WRITE_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_WRITE_BARRIER(mutex_unlock(&test_mutex), true);
KCSAN_EXPECT_RW_BARRIER(mb(), true);
KCSAN_EXPECT_RW_BARRIER(wmb(), true);
KCSAN_EXPECT_RW_BARRIER(rmb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_wmb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_rmb(), true);
KCSAN_EXPECT_RW_BARRIER(dma_wmb(), true);
KCSAN_EXPECT_RW_BARRIER(dma_rmb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb__before_atomic(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb__after_atomic(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb__after_spinlock(), true);
KCSAN_EXPECT_RW_BARRIER(smp_store_mb(test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(smp_load_acquire(&test_var), false);
KCSAN_EXPECT_RW_BARRIER(smp_store_release(&test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(xchg(&test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(xchg_release(&test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(xchg_relaxed(&test_var, 0), false);
KCSAN_EXPECT_RW_BARRIER(cmpxchg(&test_var, 0, 0), true);
KCSAN_EXPECT_RW_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
KCSAN_EXPECT_RW_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
KCSAN_EXPECT_RW_BARRIER(atomic_read(&dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_read_acquire(&dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_set(&dummy, 0), false);
KCSAN_EXPECT_RW_BARRIER(atomic_set_release(&dummy, 0), true);
KCSAN_EXPECT_RW_BARRIER(atomic_add(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return_acquire(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return_release(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_release(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(test_and_set_bit(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(test_and_clear_bit(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(test_and_change_bit(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(__clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(arch_spin_lock(&arch_spinlock), false);
KCSAN_EXPECT_RW_BARRIER(arch_spin_unlock(&arch_spinlock), true);
KCSAN_EXPECT_RW_BARRIER(spin_lock(&test_spinlock), false);
KCSAN_EXPECT_RW_BARRIER(spin_unlock(&test_spinlock), true);
KCSAN_EXPECT_RW_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_RW_BARRIER(mutex_unlock(&test_mutex), true);
#ifdef clear_bit_unlock_is_negative_byte
KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
#endif
kcsan_nestable_atomic_end();
}
/* Simple test with normal data race. */
__no_kcsan
static void test_basic(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
static const struct expect_report never = {
struct expect_report never = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
@ -469,14 +738,14 @@ static void test_basic(struct kunit *test)
__no_kcsan
static void test_concurrent_races(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
/* NULL will match any address. */
{ test_kernel_rmw_array, NULL, 0, __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
{ test_kernel_rmw_array, NULL, 0, __KCSAN_ACCESS_RW(0) },
},
};
static const struct expect_report never = {
struct expect_report never = {
.access = {
{ test_kernel_rmw_array, NULL, 0, 0 },
{ test_kernel_rmw_array, NULL, 0, 0 },
@ -498,13 +767,13 @@ static void test_concurrent_races(struct kunit *test)
__no_kcsan
static void test_novalue_change(struct kunit *test)
{
const struct expect_report expect_rw = {
struct expect_report expect_rw = {
.access = {
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
const struct expect_report expect_ww = {
struct expect_report expect_ww = {
.access = {
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
@ -530,13 +799,13 @@ static void test_novalue_change(struct kunit *test)
__no_kcsan
static void test_novalue_change_exception(struct kunit *test)
{
const struct expect_report expect_rw = {
struct expect_report expect_rw = {
.access = {
{ test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
const struct expect_report expect_ww = {
struct expect_report expect_ww = {
.access = {
{ test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
@ -556,7 +825,7 @@ static void test_novalue_change_exception(struct kunit *test)
__no_kcsan
static void test_unknown_origin(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ NULL },
@ -578,7 +847,7 @@ static void test_unknown_origin(struct kunit *test)
__no_kcsan
static void test_write_write_assume_atomic(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
@ -604,7 +873,7 @@ static void test_write_write_assume_atomic(struct kunit *test)
__no_kcsan
static void test_write_write_struct(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
@ -626,7 +895,7 @@ static void test_write_write_struct(struct kunit *test)
__no_kcsan
static void test_write_write_struct_part(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_write_struct_part, &test_struct.val[3], sizeof(test_struct.val[3]), KCSAN_ACCESS_WRITE },
@ -658,7 +927,7 @@ static void test_read_atomic_write_atomic(struct kunit *test)
__no_kcsan
static void test_read_plain_atomic_write(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_write_atomic, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC },
@ -679,7 +948,7 @@ static void test_read_plain_atomic_write(struct kunit *test)
__no_kcsan
static void test_read_plain_atomic_rmw(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_atomic_rmw, &test_var, sizeof(test_var),
@ -701,13 +970,13 @@ static void test_read_plain_atomic_rmw(struct kunit *test)
__no_kcsan
static void test_zero_size_access(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
},
};
const struct expect_report never = {
struct expect_report never = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_read_struct_zero_size, &test_struct.val[3], 0, 0 },
@ -741,7 +1010,7 @@ static void test_data_race(struct kunit *test)
__no_kcsan
static void test_assert_exclusive_writer(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
@ -759,7 +1028,7 @@ static void test_assert_exclusive_writer(struct kunit *test)
__no_kcsan
static void test_assert_exclusive_access(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
@ -777,19 +1046,19 @@ static void test_assert_exclusive_access(struct kunit *test)
__no_kcsan
static void test_assert_exclusive_access_writer(struct kunit *test)
{
const struct expect_report expect_access_writer = {
struct expect_report expect_access_writer = {
.access = {
{ test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
{ test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
},
};
const struct expect_report expect_access_access = {
struct expect_report expect_access_access = {
.access = {
{ test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
{ test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
},
};
const struct expect_report never = {
struct expect_report never = {
.access = {
{ test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
{ test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
@ -813,7 +1082,7 @@ static void test_assert_exclusive_access_writer(struct kunit *test)
__no_kcsan
static void test_assert_exclusive_bits_change(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_assert_bits_change, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
{ test_kernel_change_bits, &test_var, sizeof(test_var),
@ -844,13 +1113,13 @@ static void test_assert_exclusive_bits_nochange(struct kunit *test)
__no_kcsan
static void test_assert_exclusive_writer_scoped(struct kunit *test)
{
const struct expect_report expect_start = {
struct expect_report expect_start = {
.access = {
{ test_kernel_assert_writer_scoped, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_SCOPED },
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
},
};
const struct expect_report expect_inscope = {
struct expect_report expect_inscope = {
.access = {
{ test_enter_scope, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_SCOPED },
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
@ -871,16 +1140,16 @@ static void test_assert_exclusive_writer_scoped(struct kunit *test)
__no_kcsan
static void test_assert_exclusive_access_scoped(struct kunit *test)
{
const struct expect_report expect_start1 = {
struct expect_report expect_start1 = {
.access = {
{ test_kernel_assert_access_scoped, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_SCOPED },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
const struct expect_report expect_start2 = {
struct expect_report expect_start2 = {
.access = { expect_start1.access[0], expect_start1.access[0] },
};
const struct expect_report expect_inscope = {
struct expect_report expect_inscope = {
.access = {
{ test_enter_scope, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_SCOPED },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
@ -985,7 +1254,7 @@ static void test_atomic_builtins(struct kunit *test)
__no_kcsan
static void test_1bit_value_change(struct kunit *test)
{
const struct expect_report expect = {
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_xor_1bit, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
@ -1005,6 +1274,90 @@ static void test_1bit_value_change(struct kunit *test)
KUNIT_EXPECT_TRUE(test, match);
}
__no_kcsan
static void test_correct_barrier(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
{ test_kernel_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
},
};
bool match_expect = false;
test_struct.val[0] = 0; /* init unlocked */
begin_test_checks(test_kernel_with_memorder, test_kernel_with_memorder);
do {
match_expect = report_matches_any_reordered(&expect);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_FALSE(test, match_expect);
}
__no_kcsan
static void test_missing_barrier(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
{ test_kernel_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
},
};
bool match_expect = false;
test_struct.val[0] = 0; /* init unlocked */
begin_test_checks(test_kernel_wrong_memorder, test_kernel_wrong_memorder);
do {
match_expect = report_matches_any_reordered(&expect);
} while (!end_test_checks(match_expect));
if (IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
KUNIT_EXPECT_TRUE(test, match_expect);
else
KUNIT_EXPECT_FALSE(test, match_expect);
}
__no_kcsan
static void test_atomic_builtins_correct_barrier(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_atomic_builtin_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
{ test_kernel_atomic_builtin_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
},
};
bool match_expect = false;
test_struct.val[0] = 0; /* init unlocked */
begin_test_checks(test_kernel_atomic_builtin_with_memorder,
test_kernel_atomic_builtin_with_memorder);
do {
match_expect = report_matches_any_reordered(&expect);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_FALSE(test, match_expect);
}
__no_kcsan
static void test_atomic_builtins_missing_barrier(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_atomic_builtin_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
{ test_kernel_atomic_builtin_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
},
};
bool match_expect = false;
test_struct.val[0] = 0; /* init unlocked */
begin_test_checks(test_kernel_atomic_builtin_wrong_memorder,
test_kernel_atomic_builtin_wrong_memorder);
do {
match_expect = report_matches_any_reordered(&expect);
} while (!end_test_checks(match_expect));
if (IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
KUNIT_EXPECT_TRUE(test, match_expect);
else
KUNIT_EXPECT_FALSE(test, match_expect);
}
/*
* Generate thread counts for all test cases. Values generated are in interval
* [2, 5] followed by exponentially increasing thread counts from 8 to 32.
@ -1054,6 +1407,7 @@ static const void *nthreads_gen_params(const void *prev, char *desc)
#define KCSAN_KUNIT_CASE(test_name) KUNIT_CASE_PARAM(test_name, nthreads_gen_params)
static struct kunit_case kcsan_test_cases[] = {
KUNIT_CASE(test_barrier_nothreads),
KCSAN_KUNIT_CASE(test_basic),
KCSAN_KUNIT_CASE(test_concurrent_races),
KCSAN_KUNIT_CASE(test_novalue_change),
@ -1078,6 +1432,10 @@ static struct kunit_case kcsan_test_cases[] = {
KCSAN_KUNIT_CASE(test_seqlock_noreport),
KCSAN_KUNIT_CASE(test_atomic_builtins),
KCSAN_KUNIT_CASE(test_1bit_value_change),
KCSAN_KUNIT_CASE(test_correct_barrier),
KCSAN_KUNIT_CASE(test_missing_barrier),
KCSAN_KUNIT_CASE(test_atomic_builtins_correct_barrier),
KCSAN_KUNIT_CASE(test_atomic_builtins_missing_barrier),
{},
};
@ -1142,6 +1500,9 @@ static int test_init(struct kunit *test)
observed.nlines = 0;
spin_unlock_irqrestore(&observed.lock, flags);
if (strstr(test->name, "nothreads"))
return 0;
if (!torture_init_begin((char *)test->name, 1))
return -EBUSY;
@ -1184,6 +1545,9 @@ static void test_exit(struct kunit *test)
struct task_struct **stop_thread;
int i;
if (strstr(test->name, "nothreads"))
return;
if (torture_cleanup_begin())
return;

51
kernel/kcsan/report.c
View file

@ -215,9 +215,9 @@ static const char *get_access_type(int type)
if (type & KCSAN_ACCESS_ASSERT) {
if (type & KCSAN_ACCESS_SCOPED) {
if (type & KCSAN_ACCESS_WRITE)
return "assert no accesses (scoped)";
return "assert no accesses (reordered)";
else
return "assert no writes (scoped)";
return "assert no writes (reordered)";
} else {
if (type & KCSAN_ACCESS_WRITE)
return "assert no accesses";
@ -240,17 +240,17 @@ static const char *get_access_type(int type)
case KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
return "read-write (marked)";
case KCSAN_ACCESS_SCOPED:
return "read (scoped)";
return "read (reordered)";
case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_ATOMIC:
return "read (marked, scoped)";
return "read (marked, reordered)";
case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_WRITE:
return "write (scoped)";
return "write (reordered)";
case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
return "write (marked, scoped)";
return "write (marked, reordered)";
case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE:
return "read-write (scoped)";
return "read-write (reordered)";
case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
return "read-write (marked, scoped)";
return "read-write (marked, reordered)";
default:
BUG();
}
@ -308,10 +308,12 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
/*
* Skips to the first entry that matches the function of @ip, and then replaces
* that entry with @ip, returning the entries to skip.
* that entry with @ip, returning the entries to skip with @replaced containing
* the replaced entry.
*/
static int
replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned long ip)
replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned long ip,
unsigned long *replaced)
{
unsigned long symbolsize, offset;
unsigned long target_func;
@ -330,6 +332,7 @@ replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned lon
func -= offset;
if (func == target_func) {
*replaced = stack_entries[skip];
stack_entries[skip] = ip;
return skip;
}
@ -342,9 +345,10 @@ replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned lon
}
static int
sanitize_stack_entries(unsigned long stack_entries[], int num_entries, unsigned long ip)
sanitize_stack_entries(unsigned long stack_entries[], int num_entries, unsigned long ip,
unsigned long *replaced)
{
return ip ? replace_stack_entry(stack_entries, num_entries, ip) :
return ip ? replace_stack_entry(stack_entries, num_entries, ip, replaced) :
get_stack_skipnr(stack_entries, num_entries);
}
@ -360,6 +364,14 @@ static int sym_strcmp(void *addr1, void *addr2)
return strncmp(buf1, buf2, sizeof(buf1));
}
static void
print_stack_trace(unsigned long stack_entries[], int num_entries, unsigned long reordered_to)
{
stack_trace_print(stack_entries, num_entries, 0);
if (reordered_to)
pr_err(" |\n +-> reordered to: %pS\n", (void *)reordered_to);
}
static void print_verbose_info(struct task_struct *task)
{
if (!task)
@ -378,10 +390,12 @@ static void print_report(enum kcsan_value_change value_change,
struct other_info *other_info,
u64 old, u64 new, u64 mask)
{
unsigned long reordered_to = 0;
unsigned long stack_entries[NUM_STACK_ENTRIES] = { 0 };
int num_stack_entries = stack_trace_save(stack_entries, NUM_STACK_ENTRIES, 1);
int skipnr = sanitize_stack_entries(stack_entries, num_stack_entries, ai->ip);
int skipnr = sanitize_stack_entries(stack_entries, num_stack_entries, ai->ip, &reordered_to);
unsigned long this_frame = stack_entries[skipnr];
unsigned long other_reordered_to = 0;
unsigned long other_frame = 0;
int other_skipnr = 0; /* silence uninit warnings */
@ -394,7 +408,7 @@ static void print_report(enum kcsan_value_change value_change,
if (other_info) {
other_skipnr = sanitize_stack_entries(other_info->stack_entries,
other_info->num_stack_entries,
other_info->ai.ip);
other_info->ai.ip, &other_reordered_to);
other_frame = other_info->stack_entries[other_skipnr];
/* @value_change is only known for the other thread */
@ -434,10 +448,9 @@ static void print_report(enum kcsan_value_change value_change,
other_info->ai.cpu_id);
/* Print the other thread's stack trace. */
stack_trace_print(other_info->stack_entries + other_skipnr,
print_stack_trace(other_info->stack_entries + other_skipnr,
other_info->num_stack_entries - other_skipnr,
0);
other_reordered_to);
if (IS_ENABLED(CONFIG_KCSAN_VERBOSE))
print_verbose_info(other_info->task);
@ -451,9 +464,7 @@ static void print_report(enum kcsan_value_change value_change,
get_thread_desc(ai->task_pid), ai->cpu_id);
}
/* Print stack trace of this thread. */
stack_trace_print(stack_entries + skipnr, num_stack_entries - skipnr,
0);
print_stack_trace(stack_entries + skipnr, num_stack_entries - skipnr, reordered_to);
if (IS_ENABLED(CONFIG_KCSAN_VERBOSE))
print_verbose_info(current);

143
kernel/kcsan/selftest.c
View file

@ -7,10 +7,15 @@
#define pr_fmt(fmt) "kcsan: " fmt
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/kcsan-checks.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include "encoding.h"
@ -103,6 +108,143 @@ static bool __init test_matching_access(void)
return true;
}
/*
* Correct memory barrier instrumentation is critical to avoiding false
* positives: simple test to check at boot certain barriers are always properly
* instrumented. See kcsan_test for a more complete test.
*/
static DEFINE_SPINLOCK(test_spinlock);
static bool __init test_barrier(void)
{
#ifdef CONFIG_KCSAN_WEAK_MEMORY
struct kcsan_scoped_access *reorder_access = &current->kcsan_ctx.reorder_access;
#else
struct kcsan_scoped_access *reorder_access = NULL;
#endif
bool ret = true;
arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;
atomic_t dummy;
long test_var;
if (!reorder_access || !IS_ENABLED(CONFIG_SMP))
return true;
#define __KCSAN_CHECK_BARRIER(access_type, barrier, name) \
do { \
reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED; \
reorder_access->size = 1; \
barrier; \
if (reorder_access->size != 0) { \
pr_err("improperly instrumented type=(" #access_type "): " name "\n"); \
ret = false; \
} \
} while (0)
#define KCSAN_CHECK_READ_BARRIER(b) __KCSAN_CHECK_BARRIER(0, b, #b)
#define KCSAN_CHECK_WRITE_BARRIER(b) __KCSAN_CHECK_BARRIER(KCSAN_ACCESS_WRITE, b, #b)
#define KCSAN_CHECK_RW_BARRIER(b) __KCSAN_CHECK_BARRIER(KCSAN_ACCESS_WRITE | KCSAN_ACCESS_COMPOUND, b, #b)
kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */
KCSAN_CHECK_READ_BARRIER(mb());
KCSAN_CHECK_READ_BARRIER(rmb());
KCSAN_CHECK_READ_BARRIER(smp_mb());
KCSAN_CHECK_READ_BARRIER(smp_rmb());
KCSAN_CHECK_READ_BARRIER(dma_rmb());
KCSAN_CHECK_READ_BARRIER(smp_mb__before_atomic());
KCSAN_CHECK_READ_BARRIER(smp_mb__after_atomic());
KCSAN_CHECK_READ_BARRIER(smp_mb__after_spinlock());
KCSAN_CHECK_READ_BARRIER(smp_store_mb(test_var, 0));
KCSAN_CHECK_READ_BARRIER(smp_store_release(&test_var, 0));
KCSAN_CHECK_READ_BARRIER(xchg(&test_var, 0));
KCSAN_CHECK_READ_BARRIER(xchg_release(&test_var, 0));
KCSAN_CHECK_READ_BARRIER(cmpxchg(&test_var, 0, 0));
KCSAN_CHECK_READ_BARRIER(cmpxchg_release(&test_var, 0, 0));
KCSAN_CHECK_READ_BARRIER(atomic_set_release(&dummy, 0));
KCSAN_CHECK_READ_BARRIER(atomic_add_return(1, &dummy));
KCSAN_CHECK_READ_BARRIER(atomic_add_return_release(1, &dummy));
KCSAN_CHECK_READ_BARRIER(atomic_fetch_add(1, &dummy));
KCSAN_CHECK_READ_BARRIER(atomic_fetch_add_release(1, &dummy));
KCSAN_CHECK_READ_BARRIER(test_and_set_bit(0, &test_var));
KCSAN_CHECK_READ_BARRIER(test_and_clear_bit(0, &test_var));
KCSAN_CHECK_READ_BARRIER(test_and_change_bit(0, &test_var));
KCSAN_CHECK_READ_BARRIER(clear_bit_unlock(0, &test_var));
KCSAN_CHECK_READ_BARRIER(__clear_bit_unlock(0, &test_var));
arch_spin_lock(&arch_spinlock);
KCSAN_CHECK_READ_BARRIER(arch_spin_unlock(&arch_spinlock));
spin_lock(&test_spinlock);
KCSAN_CHECK_READ_BARRIER(spin_unlock(&test_spinlock));
KCSAN_CHECK_WRITE_BARRIER(mb());
KCSAN_CHECK_WRITE_BARRIER(wmb());
KCSAN_CHECK_WRITE_BARRIER(smp_mb());
KCSAN_CHECK_WRITE_BARRIER(smp_wmb());
KCSAN_CHECK_WRITE_BARRIER(dma_wmb());
KCSAN_CHECK_WRITE_BARRIER(smp_mb__before_atomic());
KCSAN_CHECK_WRITE_BARRIER(smp_mb__after_atomic());
KCSAN_CHECK_WRITE_BARRIER(smp_mb__after_spinlock());
KCSAN_CHECK_WRITE_BARRIER(smp_store_mb(test_var, 0));
KCSAN_CHECK_WRITE_BARRIER(smp_store_release(&test_var, 0));
KCSAN_CHECK_WRITE_BARRIER(xchg(&test_var, 0));
KCSAN_CHECK_WRITE_BARRIER(xchg_release(&test_var, 0));
KCSAN_CHECK_WRITE_BARRIER(cmpxchg(&test_var, 0, 0));
KCSAN_CHECK_WRITE_BARRIER(cmpxchg_release(&test_var, 0, 0));
KCSAN_CHECK_WRITE_BARRIER(atomic_set_release(&dummy, 0));
KCSAN_CHECK_WRITE_BARRIER(atomic_add_return(1, &dummy));
KCSAN_CHECK_WRITE_BARRIER(atomic_add_return_release(1, &dummy));
KCSAN_CHECK_WRITE_BARRIER(atomic_fetch_add(1, &dummy));
KCSAN_CHECK_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy));
KCSAN_CHECK_WRITE_BARRIER(test_and_set_bit(0, &test_var));
KCSAN_CHECK_WRITE_BARRIER(test_and_clear_bit(0, &test_var));
KCSAN_CHECK_WRITE_BARRIER(test_and_change_bit(0, &test_var));
KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock(0, &test_var));
KCSAN_CHECK_WRITE_BARRIER(__clear_bit_unlock(0, &test_var));
arch_spin_lock(&arch_spinlock);
KCSAN_CHECK_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock));
spin_lock(&test_spinlock);
KCSAN_CHECK_WRITE_BARRIER(spin_unlock(&test_spinlock));
KCSAN_CHECK_RW_BARRIER(mb());
KCSAN_CHECK_RW_BARRIER(wmb());
KCSAN_CHECK_RW_BARRIER(rmb());
KCSAN_CHECK_RW_BARRIER(smp_mb());
KCSAN_CHECK_RW_BARRIER(smp_wmb());
KCSAN_CHECK_RW_BARRIER(smp_rmb());
KCSAN_CHECK_RW_BARRIER(dma_wmb());
KCSAN_CHECK_RW_BARRIER(dma_rmb());
KCSAN_CHECK_RW_BARRIER(smp_mb__before_atomic());
KCSAN_CHECK_RW_BARRIER(smp_mb__after_atomic());
KCSAN_CHECK_RW_BARRIER(smp_mb__after_spinlock());
KCSAN_CHECK_RW_BARRIER(smp_store_mb(test_var, 0));
KCSAN_CHECK_RW_BARRIER(smp_store_release(&test_var, 0));
KCSAN_CHECK_RW_BARRIER(xchg(&test_var, 0));
KCSAN_CHECK_RW_BARRIER(xchg_release(&test_var, 0));
KCSAN_CHECK_RW_BARRIER(cmpxchg(&test_var, 0, 0));
KCSAN_CHECK_RW_BARRIER(cmpxchg_release(&test_var, 0, 0));
KCSAN_CHECK_RW_BARRIER(atomic_set_release(&dummy, 0));
KCSAN_CHECK_RW_BARRIER(atomic_add_return(1, &dummy));
KCSAN_CHECK_RW_BARRIER(atomic_add_return_release(1, &dummy));
KCSAN_CHECK_RW_BARRIER(atomic_fetch_add(1, &dummy));
KCSAN_CHECK_RW_BARRIER(atomic_fetch_add_release(1, &dummy));
KCSAN_CHECK_RW_BARRIER(test_and_set_bit(0, &test_var));
KCSAN_CHECK_RW_BARRIER(test_and_clear_bit(0, &test_var));
KCSAN_CHECK_RW_BARRIER(test_and_change_bit(0, &test_var));
KCSAN_CHECK_RW_BARRIER(clear_bit_unlock(0, &test_var));
KCSAN_CHECK_RW_BARRIER(__clear_bit_unlock(0, &test_var));
arch_spin_lock(&arch_spinlock);
KCSAN_CHECK_RW_BARRIER(arch_spin_unlock(&arch_spinlock));
spin_lock(&test_spinlock);
KCSAN_CHECK_RW_BARRIER(spin_unlock(&test_spinlock));
#ifdef clear_bit_unlock_is_negative_byte
KCSAN_CHECK_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
KCSAN_CHECK_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
#endif
kcsan_nestable_atomic_end();
return ret;
}
static int __init kcsan_selftest(void)
{
int passed = 0;
@ -120,6 +262,7 @@ static int __init kcsan_selftest(void)
RUN_TEST(test_requires);
RUN_TEST(test_encode_decode);
RUN_TEST(test_matching_access);
RUN_TEST(test_barrier);
pr_info("selftest: %d/%d tests passed\n", passed, total);
if (passed != total)

7
kernel/sched/Makefile
View file

@ -11,11 +11,10 @@ ccflags-y += $(call cc-disable-warning, unused-but-set-variable)
# that is not a function of syscall inputs. E.g. involuntary context switches.
KCOV_INSTRUMENT := n
# There are numerous data races here, however, most of them are due to plain accesses.
# This would make it even harder for syzbot to find reproducers, because these
# bugs trigger without specific input. Disable by default, but should re-enable
# eventually.
# Disable KCSAN to avoid excessive noise and performance degradation. To avoid
# false positives ensure barriers implied by sched functions are instrumented.
KCSAN_SANITIZE := n
KCSAN_INSTRUMENT_BARRIERS := y
ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is

20
lib/Kconfig.kcsan
View file

@ -191,6 +191,26 @@ config KCSAN_STRICT
closely aligns with the rules defined by the Linux-kernel memory
consistency model (LKMM).
config KCSAN_WEAK_MEMORY
bool "Enable weak memory modeling to detect missing memory barriers"
default y
depends on KCSAN_STRICT
# We can either let objtool nop __tsan_func_{entry,exit}() and builtin
# atomics instrumentation in .noinstr.text, or use a compiler that can
# implement __no_kcsan to really remove all instrumentation.
depends on STACK_VALIDATION || CC_IS_GCC || CLANG_VERSION >= 140000
help
Enable support for modeling a subset of weak memory, which allows
detecting a subset of data races due to missing memory barriers.
Depends on KCSAN_STRICT, because the options strenghtening certain
plain accesses by default (depending on !KCSAN_STRICT) reduce the
ability to detect any data races invoving reordered accesses, in
particular reordered writes.
Weak memory modeling relies on additional instrumentation and may
affect performance.
config KCSAN_REPORT_VALUE_CHANGE_ONLY
bool "Only report races where watcher observed a data value change"
default y

2
mm/Makefile
View file

@ -15,6 +15,8 @@ KCSAN_SANITIZE_slab_common.o := n
KCSAN_SANITIZE_slab.o := n
KCSAN_SANITIZE_slub.o := n
KCSAN_SANITIZE_page_alloc.o := n
# But enable explicit instrumentation for memory barriers.
KCSAN_INSTRUMENT_BARRIERS := y
# These files are disabled because they produce non-interesting and/or
# flaky coverage that is not a function of syscall inputs. E.g. slab is out of

15
scripts/Makefile.kcsan
View file

@ -9,7 +9,18 @@ endif
# Keep most options here optional, to allow enabling more compilers if absence
# of some options does not break KCSAN nor causes false positive reports.
export CFLAGS_KCSAN := -fsanitize=thread \
$(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
kcsan-cflags := -fsanitize=thread -fno-optimize-sibling-calls \
$(call cc-option,$(call cc-param,tsan-compound-read-before-write=1),$(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1))) \
$(call cc-param,tsan-distinguish-volatile=1)
ifdef CONFIG_CC_IS_GCC
# GCC started warning about operations unsupported by the TSan runtime. But
# KCSAN != TSan, so just ignore these warnings.
kcsan-cflags += -Wno-tsan
endif
ifndef CONFIG_KCSAN_WEAK_MEMORY
kcsan-cflags += $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0))
endif
export CFLAGS_KCSAN := $(kcsan-cflags)

5
scripts/Makefile.lib
View file

@ -182,6 +182,11 @@ ifeq ($(CONFIG_KCSAN),y)
_c_flags += $(if $(patsubst n%,, \
$(KCSAN_SANITIZE_$(basetarget).o)$(KCSAN_SANITIZE)y), \
$(CFLAGS_KCSAN))
# Some uninstrumented files provide implied barriers required to avoid false
# positives: set KCSAN_INSTRUMENT_BARRIERS for barrier instrumentation only.
_c_flags += $(if $(patsubst n%,, \
$(KCSAN_INSTRUMENT_BARRIERS_$(basetarget).o)$(KCSAN_INSTRUMENT_BARRIERS)n), \
-D__KCSAN_INSTRUMENT_BARRIERS__)
endif
# $(srctree)/$(src) for including checkin headers from generated source files

41
scripts/atomic/gen-atomic-instrumented.sh
View file

@ -34,6 +34,14 @@ gen_param_check()
gen_params_checks()
{
local meta="$1"; shift
local order="$1"; shift
if [ "${order}" = "_release" ]; then
printf "\tkcsan_release();\n"
elif [ -z "${order}" ] && ! meta_in "$meta" "slv"; then
# RMW with return value is fully ordered
printf "\tkcsan_mb();\n"
fi
while [ "$#" -gt 0 ]; do
gen_param_check "$meta" "$1"
@ -56,7 +64,7 @@ gen_proto_order_variant()
local ret="$(gen_ret_type "${meta}" "${int}")"
local params="$(gen_params "${int}" "${atomic}" "$@")"
local checks="$(gen_params_checks "${meta}" "$@")"
local checks="$(gen_params_checks "${meta}" "${order}" "$@")"
local args="$(gen_args "$@")"
local retstmt="$(gen_ret_stmt "${meta}")"
@ -75,29 +83,44 @@ EOF
gen_xchg()
{
local xchg="$1"; shift
local order="$1"; shift
local mult="$1"; shift
kcsan_barrier=""
if [ "${xchg%_local}" = "${xchg}" ]; then
case "$order" in
_release) kcsan_barrier="kcsan_release()" ;;
"") kcsan_barrier="kcsan_mb()" ;;
esac
fi
if [ "${xchg%${xchg#try_cmpxchg}}" = "try_cmpxchg" ] ; then
cat <<EOF
#define ${xchg}(ptr, oldp, ...) \\
#define ${xchg}${order}(ptr, oldp, ...) \\
({ \\
typeof(ptr) __ai_ptr = (ptr); \\
typeof(oldp) __ai_oldp = (oldp); \\
EOF
[ -n "$kcsan_barrier" ] && printf "\t${kcsan_barrier}; \\\\\n"
cat <<EOF
instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
instrument_atomic_write(__ai_oldp, ${mult}sizeof(*__ai_oldp)); \\
arch_${xchg}(__ai_ptr, __ai_oldp, __VA_ARGS__); \\
arch_${xchg}${order}(__ai_ptr, __ai_oldp, __VA_ARGS__); \\
})
EOF
else
cat <<EOF
#define ${xchg}(ptr, ...) \\
#define ${xchg}${order}(ptr, ...) \\
({ \\
typeof(ptr) __ai_ptr = (ptr); \\
EOF
[ -n "$kcsan_barrier" ] && printf "\t${kcsan_barrier}; \\\\\n"
cat <<EOF
instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
arch_${xchg}(__ai_ptr, __VA_ARGS__); \\
arch_${xchg}${order}(__ai_ptr, __VA_ARGS__); \\
})
EOF
@ -145,21 +168,21 @@ done
for xchg in "xchg" "cmpxchg" "cmpxchg64" "try_cmpxchg"; do
for order in "" "_acquire" "_release" "_relaxed"; do
gen_xchg "${xchg}${order}" ""
gen_xchg "${xchg}" "${order}" ""
printf "\n"
done
done
for xchg in "cmpxchg_local" "cmpxchg64_local" "sync_cmpxchg"; do
gen_xchg "${xchg}" ""
gen_xchg "${xchg}" "" ""
printf "\n"
done
gen_xchg "cmpxchg_double" "2 * "
gen_xchg "cmpxchg_double" "" "2 * "
printf "\n\n"
gen_xchg "cmpxchg_double_local" "2 * "
gen_xchg "cmpxchg_double_local" "" "2 * "
cat <<EOF

41
tools/objtool/check.c
View file

@ -849,6 +849,10 @@ static const char *uaccess_safe_builtin[] = {
"__asan_report_store16_noabort",
/* KCSAN */
"__kcsan_check_access",
"__kcsan_mb",
"__kcsan_wmb",
"__kcsan_rmb",
"__kcsan_release",
"kcsan_found_watchpoint",
"kcsan_setup_watchpoint",
"kcsan_check_scoped_accesses",
@ -1068,11 +1072,11 @@ static void annotate_call_site(struct objtool_file *file,
}
/*
* Many compilers cannot disable KCOV with a function attribute
* so they need a little help, NOP out any KCOV calls from noinstr
* text.
* Many compilers cannot disable KCOV or sanitizer calls with a function
* attribute so they need a little help, NOP out any such calls from
* noinstr text.
*/
if (insn->sec->noinstr && sym->kcov) {
if (insn->sec->noinstr && sym->profiling_func) {
if (reloc) {
reloc->type = R_NONE;
elf_write_reloc(file->elf, reloc);
@ -1987,6 +1991,31 @@ static int read_intra_function_calls(struct objtool_file *file)
return 0;
}
/*
* Return true if name matches an instrumentation function, where calls to that
* function from noinstr code can safely be removed, but compilers won't do so.
*/
static bool is_profiling_func(const char *name)
{
/*
* Many compilers cannot disable KCOV with a function attribute.
*/
if (!strncmp(name, "__sanitizer_cov_", 16))
return true;
/*
* Some compilers currently do not remove __tsan_func_entry/exit nor
* __tsan_atomic_signal_fence (used for barrier instrumentation) with
* the __no_sanitize_thread attribute, remove them. Once the kernel's
* minimum Clang version is 14.0, this can be removed.
*/
if (!strncmp(name, "__tsan_func_", 12) ||
!strcmp(name, "__tsan_atomic_signal_fence"))
return true;
return false;
}
static int classify_symbols(struct objtool_file *file)
{
struct section *sec;
@ -2007,8 +2036,8 @@ static int classify_symbols(struct objtool_file *file)
if (!strcmp(func->name, "__fentry__"))
func->fentry = true;
if (!strncmp(func->name, "__sanitizer_cov_", 16))
func->kcov = true;
if (is_profiling_func(func->name))
func->profiling_func = true;
}
}

2
tools/objtool/include/objtool/elf.h
View file

@ -58,7 +58,7 @@ struct symbol {
u8 static_call_tramp : 1;
u8 retpoline_thunk : 1;
u8 fentry : 1;
u8 kcov : 1;
u8 profiling_func : 1;
struct list_head pv_target;
};