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Commit 8eb98037 authored by Anton Blanchard's avatar Anton Blanchard Committed by Michael Ellerman
Browse files

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: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 5edb5649

arch/powerpc/kernel/process.c

+12 −4
Original line number Diff line number Diff line
@@ -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)