From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
[ Upstream commit bb4ef8fc3d193ed8d5583fb47cbeff5d8fb8302f ]
All the indirect jumps in the eBPF JIT already use expolines, except
for the tail call one.
Fixes: de5cb6eb514e ("s390: use expoline thunks in the BPF JIT")
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230129190501.1624747-3-iii@xxxxxxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/s390/net/bpf_jit_comp.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 60029baaa72ad..f2b516f8a3a64 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -1119,8 +1119,16 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
/* lg %r1,bpf_func(%r1) */
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, REG_1, REG_0,
offsetof(struct bpf_prog, bpf_func));
- /* bc 0xf,tail_call_start(%r1) */
- _EMIT4(0x47f01000 + jit->tail_call_start);
+ if (nospec_uses_trampoline()) {
+ jit->seen |= SEEN_FUNC;
+ /* aghi %r1,tail_call_start */
+ EMIT4_IMM(0xa70b0000, REG_1, jit->tail_call_start);
+ /* brcl 0xf,__s390_indirect_jump_r1 */
+ EMIT6_PCREL_RILC(0xc0040000, 0xf, jit->r1_thunk_ip);
+ } else {
+ /* bc 0xf,tail_call_start(%r1) */
+ _EMIT4(0x47f01000 + jit->tail_call_start);
+ }
/* out: */
jit->labels[0] = jit->prg;
break;
--
2.39.2
