Commit 67208692 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

tools/resolve_btfids: Warn when having multiple IDs for single type 

The kernel image can contain multiple types (structs/unions)
with the same name. This causes distinct type hierarchies in
BTF data and makes resolve_btfids fail with error like:

  BTFIDS  vmlinux
FAILED unresolved symbol udp6_sock

as reported by Qais Yousef [1].

This change adds warning when multiple types of the same name
are detected:

  BTFIDS  vmlinux
WARN: multiple IDs found for 'file': 526, 113351 - using 526
WARN: multiple IDs found for 'sk_buff': 2744, 113958 - using 2744

We keep the lower ID for the given type instance and let the
build continue.

Also changing the 'nr' variable name to 'nr_types' to avoid confusion.

[1] https://lore.kernel.org/lkml/20201229151352.6hzmjvu3qh6p2qgg@e107158-lin/



Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210105234219.970039-1-jolsa@kernel.org
parent 04901aab

tools/bpf/resolve_btfids/main.c

+12 −5
Original line number Diff line number Diff line
@@ -139,6 +139,8 @@ int eprintf(int level, int var, const char *fmt, ...) 
#define pr_debug2(fmt, ...) pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__)

#define pr_err(fmt, ...) \

	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)

#define pr_info(fmt, ...) \

	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)



static bool is_btf_id(const char *name)

{
@@ -472,7 +474,7 @@ static int symbols_resolve(struct object *obj) 
	int nr_funcs    = obj->nr_funcs;

	int err, type_id;

	struct btf *btf;

	__u32 nr;

	__u32 nr_types;



	btf = btf__parse(obj->btf ?: obj->path, NULL);

	err = libbpf_get_error(btf);
@@ -483,12 +485,12 @@ static int symbols_resolve(struct object *obj) 
	}



	err = -1;

	nr  = btf__get_nr_types(btf);

	nr_types = btf__get_nr_types(btf);



	/*

	 * Iterate all the BTF types and search for collected symbol IDs.

	 */

	for (type_id = 1; type_id <= nr; type_id++) {

	for (type_id = 1; type_id <= nr_types; type_id++) {

		const struct btf_type *type;

		struct rb_root *root;

		struct btf_id *id;
@@ -526,10 +528,15 @@ static int symbols_resolve(struct object *obj) 


		id = btf_id__find(root, str);

		if (id) {

			if (id->id) {

				pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",

					str, id->id, type_id, id->id);

			} else {

				id->id = type_id;

				(*nr)--;

			}

		}

	}



	err = 0;

out: