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
This commit is contained in:
Andrii Nakryiko 2020-12-01 22:52:43 -08:00 committed by Alexei Starovoitov
parent 0cfdcd6378
commit fa4528379a

View file

@ -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;
}