Re: [PATCH bpf-next 1/5] bpf: tracing: add support to record and check the accessed args

On Tue, Feb 20, 2024 at 11:51:01AM +0800, Menglong Dong wrote:

SNIP

+static int get_ctx_arg_idx_aligned(struct btf *btf, const struct btf_type *t,

• 		   int off)
  

+{

• const struct btf_param *args;
• u32 offset = 0, nr_args;
• int i;
• nr_args = btf_type_vlen(t);
• args = (const struct btf_param *)(t + 1);
• for (i = 0; i < nr_args; i++) {

• if (offset == off)
  

• 	return i;
  

• t = btf_type_skip_modifiers(btf, args[i].type, NULL);
  

• offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
  

• if (offset > off)
  

• 	return -1;
  

• }
• return -1;

+}

+/* This function is similar to btf_check_func_type_match(), except that it

• • only compare some function args of the function prototype t1 and t2.
• */

could we reuse btf_check_func_type_match instead? perhaps just adding extra argument with arguments bitmap to it?

jirka

+int btf_check_func_part_match(struct btf *btf1, const struct btf_type *func1,

• 	      struct btf *btf2, const struct btf_type *func2,
  

• 	      u64 func_args)
  

+{

• const struct btf_param *args1, *args2;
• u32 nargs1, i, offset = 0;
• const char *s1, *s2;
• if (!btf_type_is_func_proto(func1) || !btf_type_is_func_proto(func2))

• return -EINVAL;
  

• args1 = (const struct btf_param *)(func1 + 1);
• args2 = (const struct btf_param *)(func2 + 1);
• nargs1 = btf_type_vlen(func1);
• for (i = 0; i <= nargs1; i++) {

• const struct btf_type *t1, *t2;
  

• if (!(func_args & (1 << i)))
  

• 	goto next;
  

• if (i < nargs1) {
  

• 	int t2_index;
  

• 	/* get the index of the arg corresponding to args1[i]
  

• 	 * by the offset.
  

• 	 */
  

• 	t2_index = get_ctx_arg_idx_aligned(btf2, func2,
  

• 					   offset);
  

• 	if (t2_index < 0)
  

• 		return -EINVAL;
  

• 	t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
  

• 	t2 = btf_type_skip_modifiers(btf2, args2[t2_index].type,
  

• 				     NULL);
  

• } else {
  

• 	/* i == nargs1, this is the index of return value of t1 */
  

• 	if (get_ctx_arg_total_size(btf1, func1) !=
  

• 	    get_ctx_arg_total_size(btf2, func2))
  

• 		return -EINVAL;
  

• 	/* check the return type of t1 and t2 */
  

• 	t1 = btf_type_skip_modifiers(btf1, func1->type, NULL);
  

• 	t2 = btf_type_skip_modifiers(btf2, func2->type, NULL);
  

• }
  

• if (t1->info != t2->info ||
  

•     (btf_type_has_size(t1) && t1->size != t2->size))
  

• 	return -EINVAL;
  

• if (btf_type_is_int(t1) || btf_is_any_enum(t1))
  

• 	goto next;
  

• if (btf_type_is_struct(t1))
  

• 	goto on_struct;
  

• if (!btf_type_is_ptr(t1))
  

• 	return -EINVAL;
  

• t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
  

• t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
  

• if (!btf_type_is_struct(t1) || !btf_type_is_struct(t2))
  

• 	return -EINVAL;
  

+on_struct:

• s1 = btf_name_by_offset(btf1, t1->name_off);
  

• s2 = btf_name_by_offset(btf2, t2->name_off);
  

• if (strcmp(s1, s2))
  

• 	return -EINVAL;
  

+next:

• if (i < nargs1) {
  

• 	t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
  

• 	offset += btf_type_is_ptr(t1) ? 8 : roundup(t1->size, 8);
  

• }
  

• }
• return 0;

+}

static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t) { const char *name; -- 2.39.2