From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Mon, 6 Aug 2018 14:26:39 +0200
Subject: s390: fix br_r1_trampoline for machines without exrl
Git-commit: 26f843848bae973817b3587780ce6b7b0200d3e4
Patch-mainline: v4.19-rc1
References: git-fixes, bsc#1103421
For machines without the exrl instruction the BFP jit generates
code that uses an "br %r1" instruction located in the lowcore page.
Unfortunately there is a cut & paste error that puts an additional
"larl %r1,.+14" instruction in the code that clobbers the branch
target address in %r1. Remove the larl instruction.
Cc: <stable@vger.kernel.org> # v4.17+
Fixes: de5cb6eb51 ("s390: use expoline thunks in the BPF JIT")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
arch/s390/net/bpf_jit_comp.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index d2db8acb1a55..9d4399a87fa2 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -485,8 +485,6 @@ static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth)
/* br %r1 */
_EMIT2(0x07f1);
} else {
- /* larl %r1,.+14 */
- EMIT6_PCREL_RILB(0xc0000000, REG_1, jit->prg + 14);
/* ex 0,S390_lowcore.br_r1_tampoline */
EMIT4_DISP(0x44000000, REG_0, REG_0,
offsetof(struct lowcore, br_r1_trampoline));