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| author | Will Deacon <will.deacon@arm.com> | 2014-07-10 12:40:09 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2014-07-18 10:21:17 +0100 |
| commit | 5959e25729a521097856d71528504deda1e11584 (patch) | |
| tree | ce4fc3bb9d6b573450ea8c947d94d49eaeb6dad3 /arch/arm64/include/asm | |
| parent | ad789ba5f7086138461420d2156478d33fb61077 (diff) | |
| download | blackbird-op-linux-5959e25729a521097856d71528504deda1e11584.tar.gz blackbird-op-linux-5959e25729a521097856d71528504deda1e11584.zip | |
arm64: fpsimd: avoid restoring fpcr if the contents haven't changed
Writing to the FPCR is commonly implemented as a self-synchronising
operation in the CPU, so avoid writing to the register when the saved
value matches that in the hardware already.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm')
| -rw-r--r-- | arch/arm64/include/asm/fpsimdmacros.h | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/fpsimdmacros.h b/arch/arm64/include/asm/fpsimdmacros.h index 768414d55e64..007618b8188c 100644 --- a/arch/arm64/include/asm/fpsimdmacros.h +++ b/arch/arm64/include/asm/fpsimdmacros.h @@ -40,6 +40,19 @@ str w\tmpnr, [\state, #16 * 2 + 4] .endm +.macro fpsimd_restore_fpcr state, tmp + /* + * Writes to fpcr may be self-synchronising, so avoid restoring + * the register if it hasn't changed. + */ + mrs \tmp, fpcr + cmp \tmp, \state + b.eq 9999f + msr fpcr, \state +9999: +.endm + +/* Clobbers \state */ .macro fpsimd_restore state, tmpnr ldp q0, q1, [\state, #16 * 0] ldp q2, q3, [\state, #16 * 2] @@ -60,7 +73,7 @@ ldr w\tmpnr, [\state, #16 * 2] msr fpsr, x\tmpnr ldr w\tmpnr, [\state, #16 * 2 + 4] - msr fpcr, x\tmpnr + fpsimd_restore_fpcr x\tmpnr, \state .endm .altmacro @@ -84,7 +97,7 @@ .macro fpsimd_restore_partial state, tmpnr1, tmpnr2 ldp w\tmpnr1, w\tmpnr2, [\state] msr fpsr, x\tmpnr1 - msr fpcr, x\tmpnr2 + fpsimd_restore_fpcr x\tmpnr2, x\tmpnr1 adr x\tmpnr1, 0f ldr w\tmpnr2, [\state, #8] add \state, \state, x\tmpnr2, lsl #4 |
