[PATCH 1/2] MIPS: MSA: bugfix - disable MSA during thread switch correctly

[Leonid Yegoshin]

During thread cloning the new (child) thread should have MSA disabled even
at first thread entry. So, the code to disable MSA is moved from macro
'switch_to' to assembler function 'resume' before it switches kernel stack
to 'next' (new) thread. Call of 'disable_msa' after 'resume' in 'switch_to'
macro never called a first time entry into thread.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx>
---
 arch/mips/include/asm/switch_to.h |    1 -
 arch/mips/kernel/r4k_switch.S     |    6 ++++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/switch_to.h b/arch/mips/include/asm/switch_to.h
index e92d6c4b5ed1..0d0f7f8f8b3a 100644
--- a/arch/mips/include/asm/switch_to.h
+++ b/arch/mips/include/asm/switch_to.h
@@ -104,7 +104,6 @@ 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)					\
diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S
index 04cbbde3521b..7dbb64656bfe 100644
--- a/arch/mips/kernel/r4k_switch.S
+++ b/arch/mips/kernel/r4k_switch.S
@@ -25,6 +25,7 @@
 /* preprocessor replaces the fp in ".set fp=64" with $30 otherwise */
 #undef fp
 
+#define t4  $12
 /*
  * Offset to the current process status flags, the first 32 bytes of the
  * stack are not used.
@@ -73,6 +74,11 @@
 	cfc1	t1, fcr31
 	msa_save_all	a0
 	.set pop	/* SET_HARDFLOAT */
+	li      t4, MIPS_CONF5_MSAEN
+	mfc0    t3, CP0_CONFIG, 5
+	or      t3, t3, t4
+	xor     t3, t3, t4
+	mtc0    t3, CP0_CONFIG, 5
 
 	sw	t1, THREAD_FCR31(a0)
 	b	2f

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