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mm: kmsan: remove runtime checks from kmsan_unpoison_memory()

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Similarly to what's been done in commit 85716a80c1 ("kmsan: allow using
__msan_instrument_asm_store() inside runtime"), it should be safe to call
kmsan_unpoison_memory() from within the runtime, as it does not allocate
memory or take locks.  Remove the redundant runtime checks.

This should fix false positives seen with CONFIG_DEBUG_LIST=y when
the non-instrumented lib/stackdepot.c failed to unpoison the memory
chunks later checked by the instrumented lib/list_debug.c

Also replace the implementation of kmsan_unpoison_entry_regs() with
a call to kmsan_unpoison_memory().

Link: https://lkml.kernel.org/r/20240124173134.1165747-1-glider@google.com
Fixes: f80be4571b ("kmsan: add KMSAN runtime core")
Signed-off-by: Alexander Potapenko <glider@google.com>
Tested-by: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexander Potapenko 2024-01-24 18:31:34 +01:00 committed by Andrew Morton
parent 9af47276ed
commit d749cc7547
1 changed files with 20 additions and 30 deletions
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50
mm/kmsan/hooks.c
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@ -359,6 +359,12 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
}
/* Functions from kmsan-checks.h follow. */
/*
* To create an origin, kmsan_poison_memory() unwinds the stacks and stores it
* into the stack depot. This may cause deadlocks if done from within KMSAN
* runtime, therefore we bail out if kmsan_in_runtime().
*/
void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
{
if (!kmsan_enabled || kmsan_in_runtime())
@ -371,37 +377,11 @@ void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
}
EXPORT_SYMBOL(kmsan_poison_memory);
void kmsan_unpoison_memory(const void *address, size_t size)
{
unsigned long ua_flags;
if (!kmsan_enabled || kmsan_in_runtime())
return;
ua_flags = user_access_save();
kmsan_enter_runtime();
/* The users may want to poison/unpoison random memory. */
kmsan_internal_unpoison_memory((void *)address, size,
KMSAN_POISON_NOCHECK);
kmsan_leave_runtime();
user_access_restore(ua_flags);
}
EXPORT_SYMBOL(kmsan_unpoison_memory);
/*
* Version of kmsan_unpoison_memory() that can be called from within the KMSAN
* runtime.
*
* Non-instrumented IRQ entry functions receive struct pt_regs from assembly
* code. Those regs need to be unpoisoned, otherwise using them will result in
* false positives.
* Using kmsan_unpoison_memory() is not an option in entry code, because the
* return value of in_task() is inconsistent - as a result, certain calls to
* kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
* the registers are unpoisoned even if kmsan_in_runtime() is true in the early
* entry code.
* Unlike kmsan_poison_memory(), this function can be used from within KMSAN
* runtime, because it does not trigger allocations or call instrumented code.
*/
void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
void kmsan_unpoison_memory(const void *address, size_t size)
{
unsigned long ua_flags;
@ -409,10 +389,20 @@ void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
return;
ua_flags = user_access_save();
kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs),
/* The users may want to poison/unpoison random memory. */
kmsan_internal_unpoison_memory((void *)address, size,
KMSAN_POISON_NOCHECK);
user_access_restore(ua_flags);
}
EXPORT_SYMBOL(kmsan_unpoison_memory);
/*
* Version of kmsan_unpoison_memory() called from IRQ entry functions.
*/
void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
{
kmsan_unpoison_memory((void *)regs, sizeof(*regs));
}
void kmsan_check_memory(const void *addr, size_t size)
{