From b842d131c7983f8f0b9c9572c073130b5f2bcf11 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Sat, 6 Feb 2021 11:47:28 +0000 Subject: [PATCH] powerpc/32s: Allow constant folding in mtsr()/mfsr() On the same way as we did in wrtee(), add an alternative using mtsr/mfsr instructions instead of mtsrin/mfsrin when the segment register can be determined at compile time. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/9baed0ff9d76723ec90f1b567ddd4ac1ecc7a190.1612612022.git.christophe.leroy@csgroup.eu --- arch/powerpc/include/asm/reg.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 83a7fc3..eb4aa88 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1417,14 +1417,20 @@ static inline u32 mfsr(u32 idx) { u32 val; - asm volatile("mfsrin %0, %1" : "=r" (val): "r" (idx)); + if (__builtin_constant_p(idx)) + asm volatile("mfsr %0, %1" : "=r" (val): "i" (idx >> 28)); + else + asm volatile("mfsrin %0, %1" : "=r" (val): "r" (idx)); return val; } static inline void mtsr(u32 val, u32 idx) { - asm volatile("mtsrin %0, %1" : : "r" (val), "r" (idx)); + if (__builtin_constant_p(idx)) + asm volatile("mtsr %1, %0" : : "r" (val), "i" (idx >> 28)); + else + asm volatile("mtsrin %0, %1" : : "r" (val), "r" (idx)); } #endif -- 2.7.4