From: Eduard Zingerman <eddyz87@gmail.com>
To: bpf@vger.kernel.org, ast@kernel.org
Cc: andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev,
kernel-team@fb.com, yonghong.song@linux.dev, tj@kernel.org,
Eduard Zingerman <eddyz87@gmail.com>
Subject: [PATCH bpf-next v3 1/5] bpf: jmp_offset() and verbose_insn() utility functions
Date: Tue, 4 Mar 2025 11:50:20 -0800 [thread overview]
Message-ID: <20250304195024.2478889-2-eddyz87@gmail.com> (raw)
In-Reply-To: <20250304195024.2478889-1-eddyz87@gmail.com>
Extract two utility functions:
- One BPF jump instruction uses .imm field to encode jump offset,
while the rest use .off. Encapsulate this detail as jmp_offset()
function.
- Avoid duplicating instruction printing callback definitions by
defining a verbose_insn() function, which disassembles an
instruction into the verifier log while hiding this detail.
These functions will be used in the next patch.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
kernel/bpf/verifier.c | 40 +++++++++++++++++++++++-----------------
1 file changed, 23 insertions(+), 17 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b6664d0f6914..25910b740bbc 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3360,6 +3360,15 @@ static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
return 0;
}
+static int jmp_offset(struct bpf_insn *insn)
+{
+ u8 code = insn->code;
+
+ if (code == (BPF_JMP32 | BPF_JA))
+ return insn->imm;
+ return insn->off;
+}
+
static int check_subprogs(struct bpf_verifier_env *env)
{
int i, subprog_start, subprog_end, off, cur_subprog = 0;
@@ -3386,10 +3395,7 @@ static int check_subprogs(struct bpf_verifier_env *env)
goto next;
if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
goto next;
- if (code == (BPF_JMP32 | BPF_JA))
- off = i + insn[i].imm + 1;
- else
- off = i + insn[i].off + 1;
+ off = i + jmp_offset(&insn[i]) + 1;
if (off < subprog_start || off >= subprog_end) {
verbose(env, "jump out of range from insn %d to %d\n", i, off);
return -EINVAL;
@@ -3919,6 +3925,17 @@ static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
return btf_name_by_offset(desc_btf, func->name_off);
}
+static void verbose_insn(struct bpf_verifier_env *env, struct bpf_insn *insn)
+{
+ const struct bpf_insn_cbs cbs = {
+ .cb_call = disasm_kfunc_name,
+ .cb_print = verbose,
+ .private_data = env,
+ };
+
+ print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
+}
+
static inline void bt_init(struct backtrack_state *bt, u32 frame)
{
bt->frame = frame;
@@ -4119,11 +4136,6 @@ static bool calls_callback(struct bpf_verifier_env *env, int insn_idx);
static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
struct bpf_insn_hist_entry *hist, struct backtrack_state *bt)
{
- const struct bpf_insn_cbs cbs = {
- .cb_call = disasm_kfunc_name,
- .cb_print = verbose,
- .private_data = env,
- };
struct bpf_insn *insn = env->prog->insnsi + idx;
u8 class = BPF_CLASS(insn->code);
u8 opcode = BPF_OP(insn->code);
@@ -4141,7 +4153,7 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_stack_mask(bt));
verbose(env, "stack=%s before ", env->tmp_str_buf);
verbose(env, "%d: ", idx);
- print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
+ verbose_insn(env, insn);
}
/* If there is a history record that some registers gained range at this insn,
@@ -19273,19 +19285,13 @@ static int do_check(struct bpf_verifier_env *env)
}
if (env->log.level & BPF_LOG_LEVEL) {
- const struct bpf_insn_cbs cbs = {
- .cb_call = disasm_kfunc_name,
- .cb_print = verbose,
- .private_data = env,
- };
-
if (verifier_state_scratched(env))
print_insn_state(env, state, state->curframe);
verbose_linfo(env, env->insn_idx, "; ");
env->prev_log_pos = env->log.end_pos;
verbose(env, "%d: ", env->insn_idx);
- print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
+ verbose_insn(env, insn);
env->prev_insn_print_pos = env->log.end_pos - env->prev_log_pos;
env->prev_log_pos = env->log.end_pos;
}
--
2.48.1
next prev parent reply other threads:[~2025-03-04 19:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-04 19:50 [PATCH bpf-next v3 0/5] bpf: simple DFA-based live registers analysis Eduard Zingerman
2025-03-04 19:50 ` Eduard Zingerman [this message]
2025-03-04 19:50 ` [PATCH bpf-next v3 2/5] bpf: get_call_summary() utility function Eduard Zingerman
2025-03-04 19:50 ` [PATCH bpf-next v3 3/5] bpf: simple DFA-based live registers analysis Eduard Zingerman
2025-03-04 19:50 ` [PATCH bpf-next v3 4/5] bpf: use register liveness information for func_states_equal Eduard Zingerman
2025-03-04 19:50 ` [PATCH bpf-next v3 5/5] selftests/bpf: test cases for compute_live_registers() Eduard Zingerman
2025-03-04 21:10 ` [PATCH bpf-next v3 0/5] bpf: simple DFA-based live registers analysis patchwork-bot+netdevbpf
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