diff options
| -rw-r--r-- | arch/s390/net/bpf_jit_comp.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index bfac1ddf3447..ccb83ac3e6f3 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -1793,13 +1793,6 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, /* * Copy the tail call counter to where the callee expects it. - * - * Note 1: The callee can increment the tail call counter, but - * we do not load it back, since the x86 JIT does not do this - * either. - * - * Note 2: We assume that the verifier does not let us call the - * main program, which clears the tail call counter on entry. */ if (insn->src_reg == BPF_PSEUDO_CALL) @@ -1833,6 +1826,22 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, call_r1(jit); /* lgr %b0,%r2: load return value into %b0 */ EMIT4(0xb9040000, BPF_REG_0, REG_2); + + /* + * Copy the potentially updated tail call counter back. + */ + + if (insn->src_reg == BPF_PSEUDO_CALL) + /* + * mvc frame_off+tail_call_cnt(%r15), + * tail_call_cnt(4,%r15) + */ + _EMIT6(0xd203f000 | (jit->frame_off + + offsetof(struct prog_frame, + tail_call_cnt)), + 0xf000 | offsetof(struct prog_frame, + tail_call_cnt)); + break; } case BPF_JMP | BPF_TAIL_CALL: { |