From: Christophe Leroy Date: Fri, 22 Jan 2021 07:15:03 +0000 (+0000) Subject: powerpc/32: Use r2 in wrtspr() instead of r0 X-Git-Tag: v5.15~1232^2~37 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=867e762480f4ad4106b16299a373fa23eccf5b4b;p=platform%2Fkernel%2Flinux-starfive.git powerpc/32: Use r2 in wrtspr() instead of r0 wrtspr() is a function to write an arbitrary value in a special register. It is used on 8xx to write to SPRN_NRI, SPRN_EID and SPRN_EIE. Writing any value to one of those will play with MSR EE and MSR RI regardless of that value. r0 is used many places in the generated code and using r0 for that creates an unnecessary dependency of this instruction with preceding ones using r0 in a few places in vmlinux. r2 is most likely the most stable register as it contains the pointer to 'current'. Using r2 instead of r0 avoids that unnecessary dependency. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/69f9968f4b592fefda55227f0f7430ea612cc950.1611299687.git.christophe.leroy@csgroup.eu --- diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 9086a26..7c81d3e 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1394,8 +1394,7 @@ static inline void mtmsr_isync(unsigned long val) : "r" ((unsigned long)(v)) \ : "memory") #endif -#define wrtspr(rn) asm volatile("mtspr " __stringify(rn) ",0" : \ - : : "memory") +#define wrtspr(rn) asm volatile("mtspr " __stringify(rn) ",2" : : : "memory") static inline void wrtee(unsigned long val) {