Currently the bpf frame pointer is set to the old r15. This is
wrong because of packed stack. Fix this and adjust the frame pointer
to respect packed stack. This now generates a prolog like the following:
3ff8001c3fa: eb67f0480024 stmg %r6,%r7,72(%r15)
3ff8001c400: ebcff0780024 stmg %r12,%r15,120(%r15)
3ff8001c406: b904001f lgr %r1,%r15 <- load backchain
3ff8001c40a: 41d0f048 la %r13,72(%r15) <- load adjusted bfp
3ff8001c40e: a7fbfd98 aghi %r15,-616
3ff8001c412: e310f0980024 stg %r1,152(%r15) <- save backchain
Cc: stable@xxxxxxxxxxxxxxx # 4.0+
Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
---
arch/s390/net/bpf_jit_comp.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 7690dc8..20eb922 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -384,13 +384,16 @@ static void bpf_jit_prologue(struct bpf_jit *jit)
}
/* Setup stack and backchain */
if (jit->seen & SEEN_STACK) {
- /* lgr %bfp,%r15 (BPF frame pointer) */
- EMIT4(0xb9040000, BPF_REG_FP, REG_15);
+ if (jit->seen & SEEN_FUNC)
+ /* lgr %w1,%r15 (backchain) */
+ EMIT4(0xb9040000, REG_W1, REG_15);
+ /* la %bfp,STK_160_UNUSED(%r15) (BPF frame pointer) */
+ EMIT4_DISP(0x41000000, BPF_REG_FP, REG_15, STK_160_UNUSED);
/* aghi %r15,-STK_OFF */
EMIT4_IMM(0xa70b0000, REG_15, -STK_OFF);
if (jit->seen & SEEN_FUNC)
- /* stg %bfp,152(%r15) (backchain) */
- EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_FP, REG_0,
+ /* stg %w1,152(%r15) (backchain) */
+ EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
REG_15, 152);
}
/*
--
2.3.7
--
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