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| author | Will Deacon <will.deacon@arm.com> | 2015-04-23 22:08:49 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-07-27 17:28:51 +0300 |
| commit | c342f78217e822d2178265b0b1de232eeb717149 (patch) | |
| tree | 2c1de7284bb6671aa9cb4e8a0f85a119d64de3a2 /arch/arm64/include/asm/atomic_lse.h | |
| parent | c8366ba0fb65063b6b4f69c7af1ea74152435590 (diff) | |
| download | linux-c342f78217e822d2178265b0b1de232eeb717149.tar.xz | |
arm64: cmpxchg: patch in lse instructions when supported by the CPU
On CPUs which support the LSE atomic instructions introduced in ARMv8.1,
it makes sense to use them in preference to ll/sc sequences.
This patch introduces runtime patching of our cmpxchg primitives so that
the LSE cas instruction is used instead.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/atomic_lse.h')
| -rw-r--r-- | arch/arm64/include/asm/atomic_lse.h | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h index 6e21b5e0c9d6..b39ae4c1451a 100644 --- a/arch/arm64/include/asm/atomic_lse.h +++ b/arch/arm64/include/asm/atomic_lse.h @@ -349,4 +349,43 @@ static inline long atomic64_dec_if_positive(atomic64_t *v) #undef __LL_SC_ATOMIC64 +#define __LL_SC_CMPXCHG(op) __LL_SC_CALL(__cmpxchg_case_##op) + +#define __CMPXCHG_CASE(w, sz, name, mb, cl...) \ +static inline unsigned long __cmpxchg_case_##name(volatile void *ptr, \ + unsigned long old, \ + unsigned long new) \ +{ \ + register unsigned long x0 asm ("x0") = (unsigned long)ptr; \ + register unsigned long x1 asm ("x1") = old; \ + register unsigned long x2 asm ("x2") = new; \ + \ + asm volatile(ARM64_LSE_ATOMIC_INSN( \ + /* LL/SC */ \ + "nop\n" \ + __LL_SC_CMPXCHG(name) \ + "nop", \ + /* LSE atomics */ \ + " mov " #w "30, %" #w "[old]\n" \ + " cas" #mb #sz "\t" #w "30, %" #w "[new], %[v]\n" \ + " mov %" #w "[ret], " #w "30") \ + : [ret] "+r" (x0), [v] "+Q" (*(unsigned long *)ptr) \ + : [old] "r" (x1), [new] "r" (x2) \ + : "x30" , ##cl); \ + \ + return x0; \ +} + +__CMPXCHG_CASE(w, b, 1, ) +__CMPXCHG_CASE(w, h, 2, ) +__CMPXCHG_CASE(w, , 4, ) +__CMPXCHG_CASE(x, , 8, ) +__CMPXCHG_CASE(w, b, mb_1, al, "memory") +__CMPXCHG_CASE(w, h, mb_2, al, "memory") +__CMPXCHG_CASE(w, , mb_4, al, "memory") +__CMPXCHG_CASE(x, , mb_8, al, "memory") + +#undef __LL_SC_CMPXCHG +#undef __CMPXCHG_CASE + #endif /* __ASM_ATOMIC_LSE_H */ |