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| author | David Howells <dhowells@redhat.com> | 2008-06-05 17:07:35 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-06-05 10:31:21 -0700 |
| commit | 609a70ac927b72da647ccee7873d928d45055eae (patch) | |
| tree | a9d9268d5a517001f2895de9a0a85f7050fbcee8 /include/asm-frv | |
| parent | 5a515bcbea580a65ced92405b083299df9003748 (diff) | |
| download | lwn-609a70ac927b72da647ccee7873d928d45055eae.tar.gz lwn-609a70ac927b72da647ccee7873d928d45055eae.zip | |
FRV: ip_fast_csum() requires a memory clobber on its inline asm
ip_fast_csum() requires a memory clobber on its inline asm as it accesses
memory in a fashion that gcc can't predict.
The GCC manual says:
If your assembler instructions access memory in an unpredictable
fashion, add `memory' to the list of clobbered registers. This will
cause GCC to not keep memory values cached in registers across the
assembler instruction and not optimize stores or loads to that memory.
The bug hasn't been noticed in FRV, but it has been seen in PA-RISC.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-frv')
| -rw-r--r-- | include/asm-frv/checksum.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-frv/checksum.h b/include/asm-frv/checksum.h index 9b1689850187..269da09ff637 100644 --- a/include/asm-frv/checksum.h +++ b/include/asm-frv/checksum.h @@ -75,7 +75,7 @@ __sum16 ip_fast_csum(const void *iph, unsigned int ihl) : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (inc), "=&r"(tmp) : "0" (sum), "1" (iph), "2" (ihl), "3" (4), "m"(*(volatile struct { int _[100]; } *)iph) - : "icc0", "icc1" + : "icc0", "icc1", "memory" ); return (__force __sum16)~sum; |