From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: s390: use expoline thunks for all branches generated by the BPF JIT
References: bsc#1103421
Patch-mainline: never, code removed
Commit e1cf4befa297b149149f633eff746593e400c030 (bpf, s390x: remove
ld_abs/ld_ind) removed the code that generated the indirect branch
"basr %b5,%w1" from the BPF JIT. Older versions of the BPF which
still have support for LD_ABS/LD_IND need a patch to add the
execute trampoline for this branch instruction.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.cz>
---
arch/s390/net/bpf_jit_comp.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -1303,8 +1303,13 @@ call_fn:
/* lg %skb_data,data_off(%b6) */
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
BPF_REG_6, offsetof(struct sk_buff, data));
- /* basr %b5,%w1 (%b5 is call saved) */
- EMIT2(0x0d00, BPF_REG_5, REG_W1);
+ if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable) {
+ /* brasl %r5,__s390_indirect_jump_r1 */
+ EMIT6_PCREL_RILB(0xc0050000, BPF_REG_5, jit->r1_thunk_ip);
+ } else {
+ /* basr %b5,%w1 (%b5 is call saved) */
+ EMIT2(0x0d00, BPF_REG_5, REG_W1);
+ }
/*
* Note: For fast access we jump directly after the