linux-kernel - [PATCH 3.16 104/254] MIPS: MSA: bugfix - disable MSA correctly for new threads/processes.

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Message-ID: <lsq.1519831218.283493695@decadent.org.uk>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ralf Baechle" <ralf@...ux-mips.org>
Subject: [PATCH 3.16 104/254] MIPS: MSA: bugfix - disable MSA correctly
 for new threads/processes.

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ralf Baechle <ralf@...ux-mips.org>

commit 9cc719ab3f4f639d629ac8ff09e9b998bc006f68 upstream.

Due to the slightly odd way that new threads and processes start execution
when scheduled for the very first time they were bypassing the required
disable_msa call.

Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/mips/include/asm/switch_to.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/include/asm/switch_to.h
+++ b/arch/mips/include/asm/switch_to.h
@@ -101,7 +101,6 @@ do {									\
 	if (test_and_clear_tsk_thread_flag(prev, TIF_USEDMSA))		\
 		__fpsave = FP_SAVE_VECTOR;				\
 	(last) = resume(prev, next, task_thread_info(next), __fpsave);	\
-	disable_msa();							\
 } while (0)

 #define finish_arch_switch(prev)					\
@@ -119,6 +118,7 @@ do {									\
 	if (cpu_has_userlocal)						\
 		write_c0_userlocal(current_thread_info()->tp_value);	\
 	__restore_watch();						\
+	disable_msa();							\
 } while (0)

 #endif /* _ASM_SWITCH_TO_H */