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s390/bpf: fix lcgr instruction encoding

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[ Upstream commit bb2d267c44 ]

"masking, test in bounds 3" fails on s390, because
BPF_ALU64_IMM(BPF_NEG, BPF_REG_2, 0) ignores the top 32 bits of
BPF_REG_2. The reason is that JIT emits lcgfr instead of lcgr.
The associated comment indicates that the code was intended to
emit lcgr in the first place, it's just that the wrong opcode
was used.

Fix by using the correct opcode.

Fixes: 0546231057 ("s390/bpf: Add s390x eBPF JIT compiler backend")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ilya Leoshkevich
2019-08-12 17:03:32 +02:00
committed by Greg Kroah-Hartman
parent c1e0937ef4
commit 73d003274a
1 changed files with 1 additions and 1 deletions
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2
arch/s390/net/bpf_jit_comp.c
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@@ -841,7 +841,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
break;
case BPF_ALU64 | BPF_NEG: /* dst = -dst */
/* lcgr %dst,%dst */
EMIT4(0xb9130000, dst_reg, dst_reg);
EMIT4(0xb9030000, dst_reg, dst_reg);
break;
/*
* BPF_FROM_BE/LE