This is a note to let you know that I've just added the patch titled
powerpc/process: Fix altivec SPR not being saved
to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-process-fix-altivec-spr-not-being-saved.patch
and it can be found in the queue-4.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 01d7c2a2de47890934faba91a71d183795e4348d Mon Sep 17 00:00:00 2001
From: Oliver O'Halloran <oohall@xxxxxxxxx>
Date: Tue, 8 Mar 2016 09:08:47 +1100
Subject: powerpc/process: Fix altivec SPR not being saved
From: Oliver O'Halloran <oohall@xxxxxxxxx>
commit 01d7c2a2de47890934faba91a71d183795e4348d upstream.
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.
Fixes: 152d523e6307 ("powerpc: Create context switch helpers save_sprs() and restore_sprs()")
Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
Signed-off-by: Anton Blanchard <anton@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/process.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -854,7 +854,7 @@ void restore_tm_state(struct pt_regs *re
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
Patches currently in stable-queue which might be from oohall@xxxxxxxxx are
queue-4.5/powerpc-process-fix-altivec-spr-not-being-saved.patch
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