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s390/bpf: Fix ALU_NEG (A = -A) 

Currently the LOAD NEGATIVE (lnr) instruction is used for ALU_NEG. This
instruction always loads the negative value. Therefore, if A is already
negative, it remains unchanged. To fix this use LOAD COMPLEMENT (lcr)
instead.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Michael Holzheu 2015-01-08 14:36:21 +01:00 committed by Martin Schwidefsky
parent fbc89c952f
commit df3eed3d28
1 changed files with 2 additions and 2 deletions
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4
arch/s390/net/bpf_jit_comp.c
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@ -431,8 +431,8 @@ static int bpf_jit_insn(struct bpf_jit *jit, struct sock_filter *filter,
EMIT4_DISP(0x88500000, K);
break;
case BPF_ALU | BPF_NEG: /* A = -A */
/* lnr %r5,%r5 */
EMIT2(0x1155);
/* lcr %r5,%r5 */
EMIT2(0x1355);
break;
case BPF_JMP | BPF_JA: /* ip += K */
offset = addrs[i + K] + jit->start - jit->prg;