diff options
| author |   Anton Blanchard <anton@samba.org> | 2016-05-29 22:03:50 +1000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2016-06-14 13:58:25 +1000 |
| commit | 8eb9803723a14fd12675641b953e4ccbd86187a8 (patch) | |
| tree | 5715e1f961a191d979b26eb862873013931baab1 /arch/powerpc/kernel/process.c | |
| parent | Linux 4.7-rc3 (diff) | |
| download | linux-dev-8eb9803723a14fd12675641b953e4ccbd86187a8.tar.xz linux-dev-8eb9803723a14fd12675641b953e4ccbd86187a8.zip | |
powerpc: Avoid load hit store in __giveup_fpu() and __giveup_altivec()
In both __giveup_fpu() and __giveup_altivec() we make two modifications
to tsk->thread.regs->msr. gcc decides to do a read/modify/write of
each change, so we end up with a load hit store:
ld r9,264(r10)
rldicl r9,r9,50,1
rotldi r9,r9,14
std r9,264(r10)
...
ld r9,264(r10)
rldicl r9,r9,40,1
rotldi r9,r9,24
std r9,264(r10)
Fix this by using a temporary.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/process.c')
| -rw-r--r-- | arch/powerpc/kernel/process.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index e2f12cbcade9..a2dd3b1276ff 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -139,12 +139,16 @@ EXPORT_SYMBOL(__msr_check_and_clear); #ifdef CONFIG_PPC_FPU void __giveup_fpu(struct task_struct *tsk) { + unsigned long msr; + save_fpu(tsk); - tsk->thread.regs->msr &= ~MSR_FP; + msr = tsk->thread.regs->msr; + msr &= ~MSR_FP; #ifdef CONFIG_VSX if (cpu_has_feature(CPU_FTR_VSX)) - tsk->thread.regs->msr &= ~MSR_VSX; + msr &= ~MSR_VSX; #endif + tsk->thread.regs->msr = msr; } void giveup_fpu(struct task_struct *tsk) @@ -219,12 +223,16 @@ static int restore_fp(struct task_struct *tsk) { return 0; } static void __giveup_altivec(struct task_struct *tsk) { + unsigned long msr; + save_altivec(tsk); - tsk->thread.regs->msr &= ~MSR_VEC; + msr = tsk->thread.regs->msr; + msr &= ~MSR_VEC; #ifdef CONFIG_VSX if (cpu_has_feature(CPU_FTR_VSX)) - tsk->thread.regs->msr &= ~MSR_VSX; + msr &= ~MSR_VSX; #endif + tsk->thread.regs->msr = msr; } void giveup_altivec(struct task_struct *tsk) |