3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiko Carstens <heiko.carstens@xxxxxxxxxx> [ Upstream commit 3af57f78c38131b7a66e2b01e06fdacae01992a3 ] The s390 bpf jit compiler emits the signed divide instructions "dr" and "d" for unsigned divisions. This can cause problems: the dividend will be zero extended to a 64 bit value and the divisor is the 32 bit signed value as specified A or X accumulator, even though A and X are supposed to be treated as unsigned values. The divide instrunctions will generate an exception if the result cannot be expressed with a 32 bit signed value. This is the case if e.g. the dividend is 0xffffffff and the divisor either 1 or also 0xffffffff (signed: -1). To avoid all these issues simply use unsigned divide instructions. Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/net/bpf_jit_comp.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -335,16 +335,16 @@ static int bpf_jit_insn(struct bpf_jit * EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg)); /* lhi %r4,0 */ EMIT4(0xa7480000); - /* dr %r4,%r12 */ - EMIT2(0x1d4c); + /* dlr %r4,%r12 */ + EMIT4(0xb997004c); break; case BPF_S_ALU_DIV_K: /* A /= K */ if (K == 1) break; /* lhi %r4,0 */ EMIT4(0xa7480000); - /* d %r4,<d(K)>(%r13) */ - EMIT4_DISP(0x5d40d000, EMIT_CONST(K)); + /* dl %r4,<d(K)>(%r13) */ + EMIT6_DISP(0xe340d000, 0x0097, EMIT_CONST(K)); break; case BPF_S_ALU_MOD_X: /* A %= X */ jit->seen |= SEEN_XREG | SEEN_RET0; @@ -354,8 +354,8 @@ static int bpf_jit_insn(struct bpf_jit * EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg)); /* lhi %r4,0 */ EMIT4(0xa7480000); - /* dr %r4,%r12 */ - EMIT2(0x1d4c); + /* dlr %r4,%r12 */ + EMIT4(0xb997004c); /* lr %r5,%r4 */ EMIT2(0x1854); break; @@ -367,8 +367,8 @@ static int bpf_jit_insn(struct bpf_jit * } /* lhi %r4,0 */ EMIT4(0xa7480000); - /* d %r4,<d(K)>(%r13) */ - EMIT4_DISP(0x5d40d000, EMIT_CONST(K)); + /* dl %r4,<d(K)>(%r13) */ + EMIT6_DISP(0xe340d000, 0x0097, EMIT_CONST(K)); /* lr %r5,%r4 */ EMIT2(0x1854); break; -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html