Subject: [PATCH v3 04/21] powerpc: Return the new MSR from msr_check_and_set()

From: Cyril Bur <[email-masked]>
Date: Wed, 17 Aug 2016 13:43:06 +1000

mfmsr() is a fairly expensive call and callers of msr_check_and_set()
may want to make decisions bits in the MSR that it did not change but
may not know the value of.

This patch would avoid a two calls to mfmsr().

Signed-off-by: Cyril Bur <[email-masked]>
---
 arch/powerpc/include/asm/reg.h | 2 +-
 arch/powerpc/kernel/process.c  | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index f69f40f..0a3dde9 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1247,7 +1247,7 @@ static inline void mtmsr_isync(unsigned long val)
 				     : "memory")
 #endif
 
-extern void msr_check_and_set(unsigned long bits);
+extern unsigned long msr_check_and_set(unsigned long bits);
 extern bool strict_msr_control;
 extern void __msr_check_and_clear(unsigned long bits);
 static inline void msr_check_and_clear(unsigned long bits)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 82308fd..c42581b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -110,7 +110,7 @@ static int __init enable_strict_msr_control(char *str)
 }
 early_param("ppc_strict_facility_enable", enable_strict_msr_control);
 
-void msr_check_and_set(unsigned long bits)
+unsigned long msr_check_and_set(unsigned long bits)
 {
 	unsigned long oldmsr = mfmsr();
 	unsigned long newmsr;
@@ -124,6 +124,8 @@ void msr_check_and_set(unsigned long bits)
 
 	if (oldmsr != newmsr)
 		mtmsr_isync(newmsr);
+
+	return newmsr;
 }
 
 void __msr_check_and_clear(unsigned long bits)
-- 
2.9.3