lkml.org 
[lkml]   [2021]   [Feb]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/3] powerpc/32s: Allow constant folding in mtsr()/mfsr()
Date
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 <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 eeab7e7dc699..da103e92c112 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1418,14 +1418,20 @@ 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

--
2.25.0
\
 
 \ /
  Last update: 2021-02-06 12:49    [W:0.046 / U:0.684 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site