linux/include/asm-generic/barrier.h
Arvind Sankar 3347acc6fc compiler.h: fix barrier_data() on clang
Commit 815f0ddb34 ("include/linux/compiler*.h: make compiler-*.h
mutually exclusive") neglected to copy barrier_data() from
compiler-gcc.h into compiler-clang.h.

The definition in compiler-gcc.h was really to work around clang's more
aggressive optimization, so this broke barrier_data() on clang, and
consequently memzero_explicit() as well.

For example, this results in at least the memzero_explicit() call in
lib/crypto/sha256.c:sha256_transform() being optimized away by clang.

Fix this by moving the definition of barrier_data() into compiler.h.

Also move the gcc/clang definition of barrier() into compiler.h,
__memory_barrier() is icc-specific (and barrier() is already defined
using it in compiler-intel.h) and doesn't belong in compiler.h.

[rdunlap@infradead.org: fix ALPHA builds when SMP is not enabled]

Link: https://lkml.kernel.org/r/20201101231835.4589-1-rdunlap@infradead.org
Fixes: 815f0ddb34 ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201014212631.207844-1-nivedita@alum.mit.edu
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-14 11:26:03 -08:00

256 lines
5.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Generic barrier definitions.
*
* It should be possible to use these on really simple architectures,
* but it serves more as a starting point for new ports.
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#ifndef __ASM_GENERIC_BARRIER_H
#define __ASM_GENERIC_BARRIER_H
#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <asm/rwonce.h>
#ifndef nop
#define nop() asm volatile ("nop")
#endif
/*
* Force strict CPU ordering. And yes, this is required on UP too when we're
* talking to devices.
*
* Fall back to compiler barriers if nothing better is provided.
*/
#ifndef mb
#define mb() barrier()
#endif
#ifndef rmb
#define rmb() mb()
#endif
#ifndef wmb
#define wmb() mb()
#endif
#ifndef dma_rmb
#define dma_rmb() rmb()
#endif
#ifndef dma_wmb
#define dma_wmb() wmb()
#endif
#ifndef __smp_mb
#define __smp_mb() mb()
#endif
#ifndef __smp_rmb
#define __smp_rmb() rmb()
#endif
#ifndef __smp_wmb
#define __smp_wmb() wmb()
#endif
#ifdef CONFIG_SMP
#ifndef smp_mb
#define smp_mb() __smp_mb()
#endif
#ifndef smp_rmb
#define smp_rmb() __smp_rmb()
#endif
#ifndef smp_wmb
#define smp_wmb() __smp_wmb()
#endif
#else /* !CONFIG_SMP */
#ifndef smp_mb
#define smp_mb() barrier()
#endif
#ifndef smp_rmb
#define smp_rmb() barrier()
#endif
#ifndef smp_wmb
#define smp_wmb() barrier()
#endif
#endif /* CONFIG_SMP */
#ifndef __smp_store_mb
#define __smp_store_mb(var, value) do { WRITE_ONCE(var, value); __smp_mb(); } while (0)
#endif
#ifndef __smp_mb__before_atomic
#define __smp_mb__before_atomic() __smp_mb()
#endif
#ifndef __smp_mb__after_atomic
#define __smp_mb__after_atomic() __smp_mb()
#endif
#ifndef __smp_store_release
#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
__smp_mb(); \
WRITE_ONCE(*p, v); \
} while (0)
#endif
#ifndef __smp_load_acquire
#define __smp_load_acquire(p) \
({ \
__unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
__smp_mb(); \
(typeof(*p))___p1; \
})
#endif
#ifdef CONFIG_SMP
#ifndef smp_store_mb
#define smp_store_mb(var, value) __smp_store_mb(var, value)
#endif
#ifndef smp_mb__before_atomic
#define smp_mb__before_atomic() __smp_mb__before_atomic()
#endif
#ifndef smp_mb__after_atomic
#define smp_mb__after_atomic() __smp_mb__after_atomic()
#endif
#ifndef smp_store_release
#define smp_store_release(p, v) __smp_store_release(p, v)
#endif
#ifndef smp_load_acquire
#define smp_load_acquire(p) __smp_load_acquire(p)
#endif
#else /* !CONFIG_SMP */
#ifndef smp_store_mb
#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
#endif
#ifndef smp_mb__before_atomic
#define smp_mb__before_atomic() barrier()
#endif
#ifndef smp_mb__after_atomic
#define smp_mb__after_atomic() barrier()
#endif
#ifndef smp_store_release
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
#endif
#ifndef smp_load_acquire
#define smp_load_acquire(p) \
({ \
__unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
(typeof(*p))___p1; \
})
#endif
#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_load_acquire(p) __smp_load_acquire(p)
/**
* smp_acquire__after_ctrl_dep() - Provide ACQUIRE ordering after a control dependency
*
* A control dependency provides a LOAD->STORE order, the additional RMB
* provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
* aka. (load)-ACQUIRE.
*
* Architectures that do not do load speculation can have this be barrier().
*/
#ifndef smp_acquire__after_ctrl_dep
#define smp_acquire__after_ctrl_dep() smp_rmb()
#endif
/**
* smp_cond_load_relaxed() - (Spin) wait for cond with no ordering guarantees
* @ptr: pointer to the variable to wait on
* @cond: boolean expression to wait for
*
* Equivalent to using READ_ONCE() on the condition variable.
*
* Due to C lacking lambda expressions we load the value of *ptr into a
* pre-named variable @VAL to be used in @cond.
*/
#ifndef smp_cond_load_relaxed
#define smp_cond_load_relaxed(ptr, cond_expr) ({ \
typeof(ptr) __PTR = (ptr); \
__unqual_scalar_typeof(*ptr) VAL; \
for (;;) { \
VAL = READ_ONCE(*__PTR); \
if (cond_expr) \
break; \
cpu_relax(); \
} \
(typeof(*ptr))VAL; \
})
#endif
/**
* smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering
* @ptr: pointer to the variable to wait on
* @cond: boolean expression to wait for
*
* Equivalent to using smp_load_acquire() on the condition variable but employs
* the control dependency of the wait to reduce the barrier on many platforms.
*/
#ifndef smp_cond_load_acquire
#define smp_cond_load_acquire(ptr, cond_expr) ({ \
__unqual_scalar_typeof(*ptr) _val; \
_val = smp_cond_load_relaxed(ptr, cond_expr); \
smp_acquire__after_ctrl_dep(); \
(typeof(*ptr))_val; \
})
#endif
/*
* pmem_wmb() ensures that all stores for which the modification
* are written to persistent storage by preceding instructions have
* updated persistent storage before any data access or data transfer
* caused by subsequent instructions is initiated.
*/
#ifndef pmem_wmb
#define pmem_wmb() wmb()
#endif
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_GENERIC_BARRIER_H */