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powerpc: Use rol32() instead of opencoding in csum_fold()

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rol32(x, 16) will do the rotate using rlwinm.

No need to open code using inline assembly.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/794337eff7bb803d2c4e67d9eee635390c4c48fe.1646812553.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2022-03-09 08:56:14 +01:00 committed by Michael Ellerman
parent e6f6390ab7
commit a1ae431705
1 changed files with 8 additions and 7 deletions
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15
arch/powerpc/include/asm/checksum.h
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@ -38,14 +38,15 @@ extern __wsum csum_and_copy_to_user(const void *src, void __user *dst,
*/
static inline __sum16 csum_fold(__wsum sum)
{
unsigned int tmp;
u32 tmp = (__force u32)sum;
/* swap the two 16-bit halves of sum */
__asm__("rlwinm %0,%1,16,0,31" : "=r" (tmp) : "r" (sum));
/* if there is a carry from adding the two 16-bit halves,
it will carry from the lower half into the upper half,
giving us the correct sum in the upper half. */
return (__force __sum16)(~((__force u32)sum + tmp) >> 16);
/*
* swap the two 16-bit halves of sum
* if there is a carry from adding the two 16-bit halves,
* it will carry from the lower half into the upper half,
* giving us the correct sum in the upper half.
*/
return (__force __sum16)(~(tmp + rol32(tmp, 16)) >> 16);
}
static inline u32 from64to32(u64 x)