tools/bpftool: Auto-detect split BTFs in common cases
In case of working with module's split BTF from /sys/kernel/btf/*,
auto-substitute /sys/kernel/btf/vmlinux as the base BTF. This makes using
bpftool with module BTFs faster and simpler.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201202065244.530571-4-andrii@kernel.org
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index bd46af6..94cd3ba 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -357,11 +357,13 @@ static int dump_btf_raw(const struct btf *btf,
dump_btf_type(btf, root_type_ids[i], t);
}
} else {
+ const struct btf *base;
int cnt = btf__get_nr_types(btf);
int start_id = 1;
- if (base_btf)
- start_id = btf__get_nr_types(base_btf) + 1;
+ base = btf__base_btf(btf);
+ if (base)
+ start_id = btf__get_nr_types(base) + 1;
for (i = start_id; i <= cnt; i++) {
t = btf__type_by_id(btf, i);
@@ -428,7 +430,7 @@ static int dump_btf_c(const struct btf *btf,
static int do_dump(int argc, char **argv)
{
- struct btf *btf = NULL;
+ struct btf *btf = NULL, *base = NULL;
__u32 root_type_ids[2];
int root_type_cnt = 0;
bool dump_c = false;
@@ -502,7 +504,21 @@ static int do_dump(int argc, char **argv)
}
NEXT_ARG();
} else if (is_prefix(src, "file")) {
- btf = btf__parse_split(*argv, base_btf);
+ const char sysfs_prefix[] = "/sys/kernel/btf/";
+ const char sysfs_vmlinux[] = "/sys/kernel/btf/vmlinux";
+
+ if (!base_btf &&
+ strncmp(*argv, sysfs_prefix, sizeof(sysfs_prefix) - 1) == 0 &&
+ strcmp(*argv, sysfs_vmlinux) != 0) {
+ base = btf__parse(sysfs_vmlinux, NULL);
+ if (libbpf_get_error(base)) {
+ p_err("failed to parse vmlinux BTF at '%s': %ld\n",
+ sysfs_vmlinux, libbpf_get_error(base));
+ base = NULL;
+ }
+ }
+
+ btf = btf__parse_split(*argv, base ?: base_btf);
if (IS_ERR(btf)) {
err = -PTR_ERR(btf);
btf = NULL;
@@ -567,6 +583,7 @@ static int do_dump(int argc, char **argv)
done:
close(fd);
btf__free(btf);
+ btf__free(base);
return err;
}