From 8eb9803723a14fd12675641b953e4ccbd86187a8 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Sun, 29 May 2016 22:03:50 +1000 Subject: [PATCH] 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 Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/process.c | 16 ++++++++++++---- 1 file 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) -- 2.30.2