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locking/barriers, kcsan: Support generic instrumentation

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Thus far only smp_*() barriers had been defined by asm-generic/barrier.h
based on __smp_*() barriers, because the !SMP case is usually generic.

With the introduction of instrumentation, it also makes sense to have
asm-generic/barrier.h assist in the definition of instrumented versions
of mb(), rmb(), wmb(), dma_rmb(), and dma_wmb().

Because there is no requirement to distinguish the !SMP case, the
definition can be simpler: we can avoid also providing fallbacks for the
__ prefixed cases, and only check if `defined(__<barrier>)`, to finally
define the KCSAN-instrumented versions.

This also allows for the compiler to complain if an architecture
accidentally defines both the normal and __ prefixed variant.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Marco Elver 2021-11-30 12:44:23 +01:00 committed by Paul E. McKenney
parent f948666de5
commit 2505a51ac6
1 changed files with 25 additions and 0 deletions
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25
include/asm-generic/barrier.h
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@ -21,6 +21,31 @@
#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.