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| author | Alexei Starovoitov <ast@kernel.org> | 2024-06-20 19:48:29 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-06-20 19:48:29 -0700 |
| commit | 3b06304370931f90cd6f50ea9dd55603429b13dc (patch) | |
| tree | bc2ef689e85ff2ba195560840d0171d8e3629887 | |
| parent | f6afdaf72af7583d251bd569ded8d7d1eeb849c2 (diff) | |
| parent | f663a03c8e35c5156bad073a4a8f5e673d656e3f (diff) | |
Merge branch 'bpf-verifier-correct-tail_call_reachable-for-bpf-prog'
Leon Hwang says:
====================
bpf, verifier: Correct tail_call_reachable for bpf prog
It's confusing to inspect 'prog->aux->tail_call_reachable' with drgn[0],
when bpf prog has tail call but 'tail_call_reachable' is false.
This patch corrects 'tail_call_reachable' when bpf prog has tail call.
Therefore, it's unnecessary to detect tail call in x86 jit. Let's remove
it.
Changes:
v1 -> v2:
* Address comment from Yonghong:
* Remove unnecessary tail call detection in x86 jit.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
---
Links:
[0] https://github.com/osandov/drgn
====================
Link: https://lore.kernel.org/r/20240610124224.34673-1-hffilwlqm@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 11 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 4 |
2 files changed, 5 insertions, 10 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 5159c7a22922..7c130001fbfe 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1234,13 +1234,11 @@ bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs) } static void detect_reg_usage(struct bpf_insn *insn, int insn_cnt, - bool *regs_used, bool *tail_call_seen) + bool *regs_used) { int i; for (i = 1; i <= insn_cnt; i++, insn++) { - if (insn->code == (BPF_JMP | BPF_TAIL_CALL)) - *tail_call_seen = true; if (insn->dst_reg == BPF_REG_6 || insn->src_reg == BPF_REG_6) regs_used[0] = true; if (insn->dst_reg == BPF_REG_7 || insn->src_reg == BPF_REG_7) @@ -1324,7 +1322,6 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image struct bpf_insn *insn = bpf_prog->insnsi; bool callee_regs_used[4] = {}; int insn_cnt = bpf_prog->len; - bool tail_call_seen = false; bool seen_exit = false; u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY]; u64 arena_vm_start, user_vm_start; @@ -1336,11 +1333,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image arena_vm_start = bpf_arena_get_kern_vm_start(bpf_prog->aux->arena); user_vm_start = bpf_arena_get_user_vm_start(bpf_prog->aux->arena); - detect_reg_usage(insn, insn_cnt, callee_regs_used, - &tail_call_seen); - - /* tail call's presence in current prog implies it is reachable */ - tail_call_reachable |= tail_call_seen; + detect_reg_usage(insn, insn_cnt, callee_regs_used); emit_prologue(&prog, bpf_prog->aux->stack_depth, bpf_prog_was_classic(bpf_prog), tail_call_reachable, diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index dcbbf5f64c5d..ffe98a788c33 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2982,8 +2982,10 @@ static int check_subprogs(struct bpf_verifier_env *env) if (code == (BPF_JMP | BPF_CALL) && insn[i].src_reg == 0 && - insn[i].imm == BPF_FUNC_tail_call) + insn[i].imm == BPF_FUNC_tail_call) { subprog[cur_subprog].has_tail_call = true; + subprog[cur_subprog].tail_call_reachable = true; + } if (BPF_CLASS(code) == BPF_LD && (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND)) subprog[cur_subprog].has_ld_abs = true; |