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Message-ID: <lsq.1491052670.178507888@decadent.org.uk>
Date: Sat, 01 Apr 2017 14:17:50 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org, "Arnd Bergmann" <arnd@...db.de>,
linux-mips@...ux-mips.org, "Ralf Baechle" <ralf@...ux-mips.org>,
"Paul Burton" <paul.burton@...tec.com>
Subject: [PATCH 3.16 05/19] MIPS: save/disable MSA in lose_fpu
3.16.43-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Paul Burton <paul.burton@...tec.com>
commit 33c771ba5c5d067f85a5a6c4b11047219b5b8f4e upstream.
The kernel depends upon MSA never being enabled when the FPU is not, a
condition which is currently violated in a few places (whilst saving
sigcontext, following mips_cpu_save). Catch all the problem cases by
disabling MSA in lose_fpu, after saving context if necessary.
Signed-off-by: Paul Burton <paul.burton@...tec.com>
Cc: linux-mips@...ux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7302/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Arnd Bergmann <arnd@...db.de>
---
arch/mips/include/asm/fpu.h | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
--- a/arch/mips/include/asm/fpu.h
+++ b/arch/mips/include/asm/fpu.h
@@ -21,6 +21,7 @@
#include <asm/hazards.h>
#include <asm/processor.h>
#include <asm/current.h>
+#include <asm/msa.h>
#ifdef CONFIG_MIPS_MT_FPAFF
#include <asm/mips_mt.h>
@@ -141,13 +142,21 @@ static inline int own_fpu(int restore)
static inline void lose_fpu(int save)
{
preempt_disable();
- if (is_fpu_owner()) {
+ if (is_msa_enabled()) {
+ if (save) {
+ save_msa(current);
+ asm volatile("cfc1 %0, $31"
+ : "=r"(current->thread.fpu.fcr31));
+ }
+ disable_msa();
+ clear_thread_flag(TIF_USEDMSA);
+ } else if (is_fpu_owner()) {
if (save)
_save_fp(current);
- KSTK_STATUS(current) &= ~ST0_CU1;
- clear_thread_flag(TIF_USEDFPU);
__disable_fpu();
}
+ KSTK_STATUS(current) &= ~ST0_CU1;
+ clear_thread_flag(TIF_USEDFPU);
preempt_enable();
}
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