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| author |   Andrew Murray <andrew.murray@arm.com> | 2019-08-28 18:50:07 +0100 |
|---|---|---|
| committer |   Will Deacon <will@kernel.org> | 2019-08-29 15:53:42 +0100 |
| commit | addfc38672c73efd5c4e559a2e455b086e3e20c5 (patch) | |
| tree | e3bc9622b3b208a628d081e37be257ab5ad99a84 /arch/arm64/include/asm/lse.h | |
| parent | arm64: Use correct ll/sc atomic constraints (diff) | |
| download | linux-dev-addfc38672c73efd5c4e559a2e455b086e3e20c5.tar.xz linux-dev-addfc38672c73efd5c4e559a2e455b086e3e20c5.zip | |
arm64: atomics: avoid out-of-line ll/sc atomics
When building for LSE atomics (CONFIG_ARM64_LSE_ATOMICS), if the hardware
or toolchain doesn't support it the existing code will fallback to ll/sc
atomics. It achieves this by branching from inline assembly to a function
that is built with special compile flags. Further this results in the
clobbering of registers even when the fallback isn't used increasing
register pressure.
Improve this by providing inline implementations of both LSE and
ll/sc and use a static key to select between them, which allows for the
compiler to generate better atomics code. Put the LL/SC fallback atomics
in their own subsection to improve icache performance.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/include/asm/lse.h')
| -rw-r--r-- | arch/arm64/include/asm/lse.h | 11 |
1 files changed, 0 insertions, 11 deletions
diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h index 8262325e2fc6..52b80846d1b7 100644 --- a/arch/arm64/include/asm/lse.h +++ b/arch/arm64/include/asm/lse.h @@ -22,14 +22,6 @@ __asm__(".arch_extension lse"); -/* Move the ll/sc atomics out-of-line */ -#define __LL_SC_INLINE notrace -#define __LL_SC_PREFIX(x) __ll_sc_##x -#define __LL_SC_EXPORT(x) EXPORT_SYMBOL(__LL_SC_PREFIX(x)) - -/* Macro for constructing calls to out-of-line ll/sc atomics */ -#define __LL_SC_CALL(op) "bl\t" __stringify(__LL_SC_PREFIX(op)) "\n" -#define __LL_SC_CLOBBERS "x16", "x17", "x30" /* In-line patching at runtime */ #define ARM64_LSE_ATOMIC_INSN(llsc, lse) \ @@ -46,9 +38,6 @@ __asm__(".arch_extension lse"); #else /* __ASSEMBLER__ */ -#define __LL_SC_INLINE static inline -#define __LL_SC_PREFIX(x) x -#define __LL_SC_EXPORT(x) #define ARM64_LSE_ATOMIC_INSN(llsc, lse) llsc |