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powerpc/32s: Allow constant folding in mtsr()/mfsr()

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/9baed0ff9d76723ec90f1b567ddd4ac1ecc7a190.1612612022.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2021-02-06 11:47:28 +00:00 • committed by Michael Ellerman
parent 179ae57dba
commit b842d131c7
1 changed files with 8 additions and 2 deletions
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10
arch/powerpc/include/asm/reg.h
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@ -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