On Wed, 2016-08-17 at 13:43 +1000, Cyril Bur wrote:
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.
I can't grok this. =C2=A0Please reword.
Mikey
quoted hunk ↗ jump to hunk
This patch would avoid a two calls to mfmsr().
=20
Signed-off-by: Cyril Bur <redacted>
---
=C2=A0arch/powerpc/include/asm/reg.h | 2 +-
=C2=A0arch/powerpc/kernel/process.c=C2=A0=C2=A0| 4 +++-
=C2=A02 files changed, 4 insertions(+), 2 deletions(-)
=20
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)
=C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0: "memory")
=C2=A0#endif
=C2=A0
-extern void msr_check_and_set(unsigned long bits);
+extern unsigned long msr_check_and_set(unsigned long bits);
=C2=A0extern bool strict_msr_control;
=C2=A0extern void __msr_check_and_clear(unsigned long bits);
=C2=A0static 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)
=C2=A0}
=C2=A0early_param("ppc_strict_facility_enable", enable_strict_msr_control=
);
quoted hunk ↗ jump to hunk
=C2=A0
-void msr_check_and_set(unsigned long bits)
+unsigned long msr_check_and_set(unsigned long bits)
=C2=A0{
=C2=A0 unsigned long oldmsr =3D mfmsr();
=C2=A0 unsigned long newmsr;@@ -124,6 +124,8 @@ void msr_check_and_set(unsigned long bits)
=C2=A0
=C2=A0 if (oldmsr !=3D newmsr)
=C2=A0 mtmsr_isync(newmsr);
+
+ return newmsr;
=C2=A0}
=C2=A0
=C2=A0void __msr_check_and_clear(unsigned long bits)