From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-x22a.google.com (mail-pa0-x22a.google.com [IPv6:2607:f8b0:400e:c03::22a]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id DBBC81A0225 for ; Mon, 7 Mar 2016 09:34:01 +1100 (AEDT) Received: by mail-pa0-x22a.google.com with SMTP id tt10so4768572pab.3 for ; Sun, 06 Mar 2016 14:34:01 -0800 (PST) From: Oliver O'Halloran To: linuxppc-dev@lists.ozlabs.org Cc: Oliver O'Halloran Subject: [PATCH] powerpc/process: fix altivec SPR not being saved Date: Mon, 7 Mar 2016 09:33:08 +1100 Message-Id: <1457303588-29173-1-git-send-email-oohall@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , In save_sprs() in process.c contains the following test: if (cpu_has_feature(cpu_has_feature(CPU_FTR_ALTIVEC))) t->vrsave = mfspr(SPRN_VRSAVE); CPU feature with the mask 0x1 is CPU_FTR_COHERENT_ICACHE so the test is equivilent to: if (cpu_has_feature(CPU_FTR_ALTIVEC) && cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) On CPUs without support for both (i.e G5) this results in vrsave not being saved between context switches. The vector register save/restore code doesn't use VRSAVE to determine which registers to save/restore, but the value of VRSAVE is used to determine if altivec is being used in several code paths. Signed-off-by: Oliver O'Halloran --- arch/powerpc/kernel/process.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 8224852..5a4d4d1 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -855,7 +855,7 @@ void restore_tm_state(struct pt_regs *regs) static inline void save_sprs(struct thread_struct *t) { #ifdef CONFIG_ALTIVEC - if (cpu_has_feature(cpu_has_feature(CPU_FTR_ALTIVEC))) + if (cpu_has_feature(CPU_FTR_ALTIVEC)) t->vrsave = mfspr(SPRN_VRSAVE); #endif #ifdef CONFIG_PPC_BOOK3S_64 -- 2.5.0