s390/bpf: clear correct BPF accumulator register
Currently we assumed the following BPF to eBPF register mapping:
- BPF_REG_A -> BPF_REG_7
- BPF_REG_X -> BPF_REG_8
Unfortunately this mapping is wrong. The correct mapping is:
- BPF_REG_A -> BPF_REG_0
- BPF_REG_X -> BPF_REG_7
So clear the correct registers and use the BPF_REG_A and BPF_REG_X
macros instead of BPF_REG_0/7.
Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend")
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 79c731e..01ad166 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -448,13 +448,13 @@
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
BPF_REG_1, offsetof(struct sk_buff, data));
}
- /* BPF compatibility: clear A (%b7) and X (%b8) registers */
- if (REG_SEEN(BPF_REG_7))
- /* lghi %b7,0 */
- EMIT4_IMM(0xa7090000, BPF_REG_7, 0);
- if (REG_SEEN(BPF_REG_8))
- /* lghi %b8,0 */
- EMIT4_IMM(0xa7090000, BPF_REG_8, 0);
+ /* BPF compatibility: clear A (%b0) and X (%b7) registers */
+ if (REG_SEEN(BPF_REG_A))
+ /* lghi %ba,0 */
+ EMIT4_IMM(0xa7090000, BPF_REG_A, 0);
+ if (REG_SEEN(BPF_REG_X))
+ /* lghi %bx,0 */
+ EMIT4_IMM(0xa7090000, BPF_REG_X, 0);
}
/*