The C version of csum_add() as defined in include/net/checksum.h gives the
following assembly in ppc32:
0: 7c 04 1a 14 add r0,r4,r3
4: 7c 64 00 10 subfc r3,r4,r0
8: 7c 63 19 10 subfe r3,r3,r3
c: 7c 63 00 50 subf r3,r3,r0
and the following in ppc64:
0xc000000000001af8 <+0>: add r3,r3,r4
0xc000000000001afc <+4>: cmplw cr7,r3,r4
0xc000000000001b00 <+8>: mfcr r4
0xc000000000001b04 <+12>: rlwinm r4,r4,29,31,31
0xc000000000001b08 <+16>: add r3,r4,r3
0xc000000000001b0c <+20>: clrldi r3,r3,32
0xc000000000001b10 <+24>: blr
include/net/checksum.h also offers the possibility to define an arch specific
function.
This patch provides a specific csum_add() inline function.
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
arch/powerpc/include/asm/checksum.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/powerpc/include/asm/checksum.h
b/arch/powerpc/include/asm/checksum.h
index 5e43d2d..e8d9ef4 100644
--- a/arch/powerpc/include/asm/checksum.h
+++ b/arch/powerpc/include/asm/checksum.h
@@ -130,6 +130,22 @@ static inline __sum16 csum_tcpudp_magic(__be32 saddr,
__be32 daddr,
return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
}
+#define HAVE_ARCH_CSUM_ADD
+static inline __wsum csum_add(__wsum csum, __wsum addend)
+{
+#ifdef __powerpc64__
+ u64 res = (__force u64)csum;
+
+ res += (__force u64)addend;
+ return (__force __wsum)((u32)res + (res >> 32));
+#else
+ asm("addc %0,%0,%1;"
+ "addze %0,%0;"
+ : "+r" (csum) : "r" (addend));
+ return csum;
+#endif
+}
+
#endif
#endif /* __KERNEL__ */
#endif
--
2.1.0
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