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| author | Mark Rutland <mark.rutland@arm.com> | 2023-06-05 08:00:58 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-06-05 09:57:13 +0200 |
| commit | dda5f312bb09e56e7a1c3e3851f2000eb2e9c879 (patch) | |
| tree | 2c5d77a688caffdffb4b516c1e6b00baeadb1259 /arch/arm/include | |
| parent | 497cc42bf53b55185ab3d39c634fbf09eb6681ae (diff) | |
| download | linux-dda5f312bb09e56e7a1c3e3851f2000eb2e9c879.tar.gz linux-dda5f312bb09e56e7a1c3e3851f2000eb2e9c879.tar.bz2 linux-dda5f312bb09e56e7a1c3e3851f2000eb2e9c879.zip | |
locking/atomic: arm: fix sync ops
The sync_*() ops on arch/arm are defined in terms of the regular bitops
with no special handling. This is not correct, as UP kernels elide
barriers for the fully-ordered operations, and so the required ordering
is lost when such UP kernels are run under a hypervsior on an SMP
system.
Fix this by defining sync ops with the required barriers.
Note: On 32-bit arm, the sync_*() ops are currently only used by Xen,
which requires ARMv7, but the semantics can be implemented for ARMv6+.
Fixes: e54d2f61528165bb ("xen/arm: sync_bitops")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-2-mark.rutland@arm.com
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/assembler.h | 17 | ||||
| -rw-r--r-- | arch/arm/include/asm/sync_bitops.h | 29 |
2 files changed, 42 insertions, 4 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 505a306e0271..aebe2c8f6a68 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -394,6 +394,23 @@ ALT_UP_B(.L0_\@) #endif .endm +/* + * Raw SMP data memory barrier + */ + .macro __smp_dmb mode +#if __LINUX_ARM_ARCH__ >= 7 + .ifeqs "\mode","arm" + dmb ish + .else + W(dmb) ish + .endif +#elif __LINUX_ARM_ARCH__ == 6 + mcr p15, 0, r0, c7, c10, 5 @ dmb +#else + .error "Incompatible SMP platform" +#endif + .endm + #if defined(CONFIG_CPU_V7M) /* * setmode is used to assert to be in svc mode during boot. For v7-M diff --git a/arch/arm/include/asm/sync_bitops.h b/arch/arm/include/asm/sync_bitops.h index 6f5d627c44a3..f46b3c570f92 100644 --- a/arch/arm/include/asm/sync_bitops.h +++ b/arch/arm/include/asm/sync_bitops.h @@ -14,14 +14,35 @@ * ops which are SMP safe even on a UP kernel. */ +/* + * Unordered + */ + #define sync_set_bit(nr, p) _set_bit(nr, p) #define sync_clear_bit(nr, p) _clear_bit(nr, p) #define sync_change_bit(nr, p) _change_bit(nr, p) -#define sync_test_and_set_bit(nr, p) _test_and_set_bit(nr, p) -#define sync_test_and_clear_bit(nr, p) _test_and_clear_bit(nr, p) -#define sync_test_and_change_bit(nr, p) _test_and_change_bit(nr, p) #define sync_test_bit(nr, addr) test_bit(nr, addr) -#define arch_sync_cmpxchg arch_cmpxchg +/* + * Fully ordered + */ + +int _sync_test_and_set_bit(int nr, volatile unsigned long * p); +#define sync_test_and_set_bit(nr, p) _sync_test_and_set_bit(nr, p) + +int _sync_test_and_clear_bit(int nr, volatile unsigned long * p); +#define sync_test_and_clear_bit(nr, p) _sync_test_and_clear_bit(nr, p) + +int _sync_test_and_change_bit(int nr, volatile unsigned long * p); +#define sync_test_and_change_bit(nr, p) _sync_test_and_change_bit(nr, p) + +#define arch_sync_cmpxchg(ptr, old, new) \ +({ \ + __typeof__(*(ptr)) __ret; \ + __smp_mb__before_atomic(); \ + __ret = arch_cmpxchg_relaxed((ptr), (old), (new)); \ + __smp_mb__after_atomic(); \ + __ret; \ +}) #endif |