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>

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index c52ac77408ca5cac7ad50b6a2a8a3113d8af30ca..8bc474fb52fd086348ba0fccb3b73f50a1793348 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -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;