From: Ilya Leoshkevich iii@linux.ibm.com
[ 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@linux.ibm.com Link: https://lore.kernel.org/r/20230129190501.1624747-3-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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;