@@ -2807,15 +2807,61 @@ static int bpf_core_reloc_insn(struct bpf_program *prog, int insn_off,
return 0;
}
+static struct btf *btf_load_raw(const char *path)
+{
+ struct btf *btf;
+ size_t read_cnt;
+ struct stat st;
+ void *data;
+ FILE *f;
+
+ if (stat(path, &st))
+ return ERR_PTR(-errno);
+
+ data = malloc(st.st_size);
+ if (!data)
+ return ERR_PTR(-ENOMEM);
+
+ f = fopen(path, "rb");
+ if (!f) {
+ btf = ERR_PTR(-errno);
+ goto cleanup;
+ }
+
+ read_cnt = fread(data, 1, st.st_size, f);
+ fclose(f);
+ if (read_cnt < st.st_size) {
+ btf = ERR_PTR(-EBADF);
+ goto cleanup;
+ }
+
+ btf = btf__new(data, read_cnt);
+
+cleanup:
+ free(data);
+ return btf;
+}
+
/*
* Probe few well-known locations for vmlinux kernel image and try to load BTF
* data out of it to use for target BTF.
*/
static struct btf *bpf_core_find_kernel_btf(void)
{
- const char *locations[] = {
- "/lib/modules/%1$s/vmlinux-%1$s",
- "/usr/lib/modules/%1$s/kernel/vmlinux",
+ struct {
+ const char *path_fmt;
+ bool raw_btf;
+ } locations[] = {
+ /* try canonical vmlinux BTF through sysfs first */
+ { "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
+ /* fall back to trying to find vmlinux ELF on disk otherwise */
+ { "/boot/vmlinux-%1$s" },
+ { "/lib/modules/%1$s/vmlinux-%1$s" },
+ { "/lib/modules/%1$s/build/vmlinux" },
+ { "/usr/lib/modules/%1$s/kernel/vmlinux" },
+ { "/usr/lib/debug/boot/vmlinux-%1$s" },
+ { "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
+ { "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
};
char path[PATH_MAX + 1];
struct utsname buf;
@@ -2825,14 +2871,18 @@ static struct btf *bpf_core_find_kernel_btf(void)
uname(&buf);
for (i = 0; i < ARRAY_SIZE(locations); i++) {
- snprintf(path, PATH_MAX, locations[i], buf.release);
+ snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
if (access(path, R_OK))
continue;
- btf = btf__parse_elf(path, NULL);
- pr_debug("kernel BTF load from '%s': %ld\n",
- path, PTR_ERR(btf));
+ if (locations[i].raw_btf)
+ btf = btf_load_raw(path);
+ else
+ btf = btf__parse_elf(path, NULL);
+
+ pr_debug("loading kernel BTF '%s': %ld\n",
+ path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
if (IS_ERR(btf))
continue;
Add support for loading kernel BTF from sysfs (/sys/kernel/btf/vmlinux) as a target BTF. Also extend the list of on disk search paths for vmlinux ELF image with entries that perf is searching for. Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/lib/bpf/libbpf.c | 64 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 57 insertions(+), 7 deletions(-)