[PATCH net] powerpc: use big endian to hash len and proto in csum_ipv6_magic

[Xin Long]

The function csum_ipv6_magic doesn't convert len and proto to big
endian before doing ipv6 csum hash, which is not consistent with
RFC and other arches.

Jianlin found it when ICMPv6 packets from other hosts were dropped
in the powerpc64 system.

This patch is to fix it by using instruction 'lwbrx' to do this
conversion in powerpc32/64 csum_ipv6_magic.

Fixes: e9c4943a107b ("powerpc: Implement csum_ipv6_magic in assembly")
Reported-by: Jianlin Shi <jishi at redhat.com>
Signed-off-by: Xin Long <lucien.xin at gmail.com>
---
 arch/powerpc/lib/checksum_32.S | 4 ++++
 arch/powerpc/lib/checksum_64.S | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index aa22406..7d3446e 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -325,6 +325,10 @@ _GLOBAL(csum_ipv6_magic)
 	adde	r0, r0, r9
 	lwz	r11, 12(r4)
 	adde	r0, r0, r10
+	STWX_BE	r5, 0, r1
+	lwz	r5, 0(r1)
+	STWX_BE	r6, 0, r1
+	lwz	r6, 0(r1)
 	add	r5, r5, r6	/* assumption: len + proto doesn't carry */
 	adde	r0, r0, r11
 	adde	r0, r0, r5
diff --git a/arch/powerpc/lib/checksum_64.S b/arch/powerpc/lib/checksum_64.S
index 886ed94..302e732 100644
--- a/arch/powerpc/lib/checksum_64.S
+++ b/arch/powerpc/lib/checksum_64.S
@@ -439,6 +439,10 @@ EXPORT_SYMBOL(csum_partial_copy_generic)
 _GLOBAL(csum_ipv6_magic)
 	ld	r8, 0(r3)
 	ld	r9, 8(r3)
+	STWX_BE	r5, 0, r1
+	lwz	r5, 0(r1)
+	STWX_BE	r6, 0, r1
+	lwz	r6, 0(r1)
 	add	r5, r5, r6
 	addc	r0, r8, r9
 	ld	r10, 0(r4)
-- 
2.1.0