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

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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: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210105234219.970039-1-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2021-01-06 00:42:19 +01:00 committed by Alexei Starovoitov
parent 04901aab40
commit 6720869280
1 changed files with 12 additions and 5 deletions
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17
tools/bpf/resolve_btfids/main.c
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@ -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;
@ -526,8 +528,13 @@ static int symbols_resolve(struct object *obj)
id = btf_id__find(root, str);
if (id) {
id->id = type_id;
(*nr)--;
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)--;
}
}
}