Commit 80ca3f1d authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

bpf: jmp_offset() and verbose_insn() utility functions 



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: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250304195024.2478889-2-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 5bde5750

kernel/bpf/verifier.c

+23 −17
Original line number Diff line number Diff line
@@ -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;









		}