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powerpc: Avoid load hit store in setup_sigcontext()

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In setup_sigcontext(), we set current->thread.vrsave then use it
straight after. Since current is hidden from the compiler via inline
assembly, it cannot optimise this and we end up with a load hit store.

Fix this by using a temporary.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Anton Blanchard 2016-05-29 22:03:51 +10:00 committed by Michael Ellerman
parent 8eb9803723
commit d96f234f47
1 changed files with 8 additions and 3 deletions
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11
arch/powerpc/kernel/signal_64.c
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@ -104,6 +104,7 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
*/
#ifdef CONFIG_ALTIVEC
elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
unsigned long vrsave;
#endif
unsigned long msr = regs->msr;
long err = 0;
@ -125,9 +126,13 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
/* We always copy to/from vrsave, it's 0 if we don't have or don't
* use altivec.
*/
if (cpu_has_feature(CPU_FTR_ALTIVEC))
current->thread.vrsave = mfspr(SPRN_VRSAVE);
err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
vrsave = 0;
if (cpu_has_feature(CPU_FTR_ALTIVEC)) {
vrsave = mfspr(SPRN_VRSAVE);
current->thread.vrsave = vrsave;
}
err |= __put_user(vrsave, (u32 __user *)&v_regs[33]);
#else /* CONFIG_ALTIVEC */
err |= __put_user(0, &sc->v_regs);
#endif /* CONFIG_ALTIVEC */