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s390/bpf: Add expoline to tail calls

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[ Upstream commit bb4ef8fc3d ]

All the indirect jumps in the eBPF JIT already use expolines, except
for the tail call one.

Fixes: de5cb6eb51 ("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>
This commit is contained in:
Ilya Leoshkevich 2023-01-29 20:04:55 +01:00 committed by Greg Kroah-Hartman
parent bddd22cf5c
commit 24f105f90a
1 changed files with 10 additions and 2 deletions
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12
arch/s390/net/bpf_jit_comp.c
View file

@ -1393,8 +1393,16 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
/* 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: */
if (jit->prg_buf) {
*(u16 *)(jit->prg_buf + patch_1_clrj + 2) =