From: Ilya Leoshkevich <iii@linux.ibm.com>
Subject: s390/bpf: Fix 64-bit subtraction of the -0x80000000 constant
Patch-mainline: Not yet, embargoed
References: bsc#1190601
Signed-off-by: Tony Jones <tonyj@suse.de>
---
arch/s390/net/bpf_jit_comp.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/arch/s390/net/bpf_jit_comp.c
+++ a/arch/s390/net/bpf_jit_comp.c
@@ -794,8 +794,13 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
case BPF_ALU64 | BPF_SUB | BPF_K: /* dst = dst - imm */
if (!imm)
break;
- /* agfi %dst,-imm */
- EMIT6_IMM(0xc2080000, dst_reg, -imm);
+ if (imm == -0x80000000) {
+ /* algfi %dst,0x80000000 */
+ EMIT6_IMM(0xc20a0000, dst_reg, 0x80000000);
+ } else {
+ /* agfi %dst,-imm */
+ EMIT6_IMM(0xc2080000, dst_reg, -imm);
+ }
break;
/*
* BPF_MUL
--