diff options
| author | Pavel Kozlov | 2023-08-15 19:11:36 +0400 |
|---|---|---|
| committer | Vineet Gupta | 2023-08-15 17:27:26 -0700 |
| commit | 42f51fb24fd39cc547c086ab3d8a314cc603a91c (patch) | |
| tree | 296dcde00f8246e66920889547795d8a4a91db91 /arch/arc | |
| parent | 4d3696801bad2a037832c15a8d21dfe0c529d9cd (diff) | |
ARC: atomics: Add compiler barrier to atomic operations...
... to avoid unwanted gcc optimizations
SMP kernels fail to boot with commit 596ff4a09b89
("cpumask: re-introduce constant-sized cpumask optimizations").
|
| percpu: BUG: failure at mm/percpu.c:2981/pcpu_build_alloc_info()!
|
The write operation performed by the SCOND instruction in the atomic
inline asm code is not properly passed to the compiler. The compiler
cannot correctly optimize a nested loop that runs through the cpumask
in the pcpu_build_alloc_info() function.
Fix this by add a compiler barrier (memory clobber in inline asm).
Apparently atomic ops used to have memory clobber implicitly via
surrounding smp_mb(). However commit b64be6836993c431e
("ARC: atomics: implement relaxed variants") removed the smp_mb() for
the relaxed variants, but failed to add the explicit compiler barrier.
Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/135
Cc: <stable@vger.kernel.org> # v6.3+
Fixes: b64be6836993c43 ("ARC: atomics: implement relaxed variants")
Signed-off-by: Pavel Kozlov <pavel.kozlov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
[vgupta: tweaked the changelog and added Fixes tag]
Diffstat (limited to 'arch/arc')
| -rw-r--r-- | arch/arc/include/asm/atomic-llsc.h | 6 | ||||
| -rw-r--r-- | arch/arc/include/asm/atomic64-arcv2.h | 6 |
2 files changed, 6 insertions, 6 deletions
diff --git a/arch/arc/include/asm/atomic-llsc.h b/arch/arc/include/asm/atomic-llsc.h index 1b0ffaeee16d..5258cb81a16b 100644 --- a/arch/arc/include/asm/atomic-llsc.h +++ b/arch/arc/include/asm/atomic-llsc.h @@ -18,7 +18,7 @@ static inline void arch_atomic_##op(int i, atomic_t *v) \ : [val] "=&r" (val) /* Early clobber to prevent reg reuse */ \ : [ctr] "r" (&v->counter), /* Not "m": llock only supports reg direct addr mode */ \ [i] "ir" (i) \ - : "cc"); \ + : "cc", "memory"); \ } \ #define ATOMIC_OP_RETURN(op, asm_op) \ @@ -34,7 +34,7 @@ static inline int arch_atomic_##op##_return_relaxed(int i, atomic_t *v) \ : [val] "=&r" (val) \ : [ctr] "r" (&v->counter), \ [i] "ir" (i) \ - : "cc"); \ + : "cc", "memory"); \ \ return val; \ } @@ -56,7 +56,7 @@ static inline int arch_atomic_fetch_##op##_relaxed(int i, atomic_t *v) \ [orig] "=&r" (orig) \ : [ctr] "r" (&v->counter), \ [i] "ir" (i) \ - : "cc"); \ + : "cc", "memory"); \ \ return orig; \ } diff --git a/arch/arc/include/asm/atomic64-arcv2.h b/arch/arc/include/asm/atomic64-arcv2.h index 6b6db981967a..9b5791b85471 100644 --- a/arch/arc/include/asm/atomic64-arcv2.h +++ b/arch/arc/include/asm/atomic64-arcv2.h @@ -60,7 +60,7 @@ static inline void arch_atomic64_##op(s64 a, atomic64_t *v) \ " bnz 1b \n" \ : "=&r"(val) \ : "r"(&v->counter), "ir"(a) \ - : "cc"); \ + : "cc", "memory"); \ } \ #define ATOMIC64_OP_RETURN(op, op1, op2) \ @@ -77,7 +77,7 @@ static inline s64 arch_atomic64_##op##_return_relaxed(s64 a, atomic64_t *v) \ " bnz 1b \n" \ : [val] "=&r"(val) \ : "r"(&v->counter), "ir"(a) \ - : "cc"); /* memory clobber comes from smp_mb() */ \ + : "cc", "memory"); \ \ return val; \ } @@ -99,7 +99,7 @@ static inline s64 arch_atomic64_fetch_##op##_relaxed(s64 a, atomic64_t *v) \ " bnz 1b \n" \ : "=&r"(orig), "=&r"(val) \ : "r"(&v->counter), "ir"(a) \ - : "cc"); /* memory clobber comes from smp_mb() */ \ + : "cc", "memory"); \ \ return orig; \ } |