x86: bpf_jit: support negative offsets

commit fdfaf64e75397567257e1051931f9a3377360665 upstream.

Commit a998d43423 claimed to introduce negative offset support to x86 jit,
but it couldn't be working, since at the time of the execution
of LD+ABS or LD+IND instructions via call into
bpf_internal_load_pointer_neg_helper() the %edx (3rd argument of this func)
had junk value instead of access size in bytes (1 or 2 or 4).

Store size into %edx instead of %ecx (what original commit intended to do)

Fixes: a998d43423 ("bpf jit: Let the x86 jit handle negative offsets")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Jan Seiffert <kaffeemonster@googlemail.com>
Cc: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexei Starovoitov 2014-03-10 15:56:51 -07:00 committed by Greg Kroah-Hartman
parent 21680f38b5
commit 32f139873e
1 changed files with 1 additions and 1 deletions

View File

@ -140,7 +140,7 @@ bpf_slow_path_byte_msh:
push %r9; \
push SKBDATA; \
/* rsi already has offset */ \
mov $SIZE,%ecx; /* size */ \
mov $SIZE,%edx; /* size */ \
call bpf_internal_load_pointer_neg_helper; \
test %rax,%rax; \
pop SKBDATA; \