From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rHdhL3qKhzDqPm for ; Sun, 29 May 2016 22:04:02 +1000 (AEST) From: Anton Blanchard To: mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com, acsawdey@linux.vnet.ibm.com Cc: linuxppc-dev@lists.ozlabs.org Subject: [PATCH 2/3] powerpc: Avoid load hit store in setup_sigcontext() Date: Sun, 29 May 2016 22:03:51 +1000 Message-Id: <1464523432-12605-2-git-send-email-anton@ozlabs.org> In-Reply-To: <1464523432-12605-1-git-send-email-anton@ozlabs.org> References: <1464523432-12605-1-git-send-email-anton@ozlabs.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Anton Blanchard 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 --- arch/powerpc/kernel/signal_64.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index 2552079..7e49984 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -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 */ -- 2.7.4