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-rw-r--r--tools/lib/bpf/bpf.c46
-rw-r--r--tools/lib/bpf/btf.c274
-rw-r--r--tools/lib/bpf/btf.h50
-rw-r--r--tools/lib/bpf/libbpf.c87
4 files changed, 442 insertions, 15 deletions
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 9b5cf22c4e64..836447bb4f14 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -186,6 +186,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
char *log_buf, size_t log_buf_sz)
{
union bpf_attr attr;
+ void *finfo = NULL;
__u32 name_len;
int fd;
@@ -216,12 +217,55 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
if (fd >= 0 || !log_buf || !log_buf_sz)
return fd;
+ /* After bpf_prog_load, the kernel may modify certain attributes
+ * to give user space a hint how to deal with loading failure.
+ * Check to see whether we can make some changes and load again.
+ */
+ if (errno == E2BIG && attr.func_info_cnt &&
+ attr.func_info_rec_size < load_attr->func_info_rec_size) {
+ __u32 actual_rec_size = load_attr->func_info_rec_size;
+ __u32 expected_rec_size = attr.func_info_rec_size;
+ __u32 finfo_cnt = load_attr->func_info_cnt;
+ __u64 finfo_len = actual_rec_size * finfo_cnt;
+ const void *orecord;
+ void *nrecord;
+ int i;
+
+ finfo = malloc(finfo_len);
+ if (!finfo)
+ /* further try with log buffer won't help */
+ return fd;
+
+ /* zero out bytes kernel does not understand */
+ orecord = load_attr->func_info;
+ nrecord = finfo;
+ for (i = 0; i < load_attr->func_info_cnt; i++) {
+ memcpy(nrecord, orecord, expected_rec_size);
+ memset(nrecord + expected_rec_size, 0,
+ actual_rec_size - expected_rec_size);
+ orecord += actual_rec_size;
+ nrecord += actual_rec_size;
+ }
+
+ /* try with corrected func info records */
+ attr.func_info = ptr_to_u64(finfo);
+ attr.func_info_rec_size = load_attr->func_info_rec_size;
+
+ fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+
+ if (fd >= 0 || !log_buf || !log_buf_sz)
+ goto done;
+ }
+
/* Try again with log */
attr.log_buf = ptr_to_u64(log_buf);
attr.log_size = log_buf_sz;
attr.log_level = 1;
log_buf[0] = 0;
- return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+ fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+done:
+ free(finfo);
+ return fd;
}
int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 31225e64766f..fe87cb48a6a9 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -37,6 +37,18 @@ struct btf {
int fd;
};
+struct btf_ext {
+ void *func_info;
+ __u32 func_info_rec_size;
+ __u32 func_info_len;
+};
+
+/* The minimum bpf_func_info checked by the loader */
+struct bpf_func_info_min {
+ __u32 insn_offset;
+ __u32 type_id;
+};
+
static int btf_add_type(struct btf *btf, struct btf_type *t)
{
if (btf->types_size - btf->nr_types < 2) {
@@ -397,3 +409,265 @@ const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
else
return NULL;
}
+
+static int btf_ext_validate_func_info(const void *finfo, __u32 size,
+ btf_print_fn_t err_log)
+{
+ int sec_hdrlen = sizeof(struct btf_sec_func_info);
+ __u32 size_left, num_records, record_size;
+ const struct btf_sec_func_info *sinfo;
+ __u64 total_record_size;
+
+ /* At least a func_info record size */
+ if (size < sizeof(__u32)) {
+ elog("BTF.ext func_info record size not found");
+ return -EINVAL;
+ }
+
+ /* The record size needs to meet below minimum standard */
+ record_size = *(__u32 *)finfo;
+ if (record_size < sizeof(struct bpf_func_info_min) ||
+ record_size % sizeof(__u32)) {
+ elog("BTF.ext func_info invalid record size");
+ return -EINVAL;
+ }
+
+ sinfo = finfo + sizeof(__u32);
+ size_left = size - sizeof(__u32);
+
+ /* If no func_info records, return failure now so .BTF.ext
+ * won't be used.
+ */
+ if (!size_left) {
+ elog("BTF.ext no func info records");
+ return -EINVAL;
+ }
+
+ while (size_left) {
+ if (size_left < sec_hdrlen) {
+ elog("BTF.ext func_info header not found");
+ return -EINVAL;
+ }
+
+ num_records = sinfo->num_func_info;
+ if (num_records == 0) {
+ elog("incorrect BTF.ext num_func_info");
+ return -EINVAL;
+ }
+
+ total_record_size = sec_hdrlen +
+ (__u64)num_records * record_size;
+ if (size_left < total_record_size) {
+ elog("incorrect BTF.ext num_func_info");
+ return -EINVAL;
+ }
+
+ size_left -= total_record_size;
+ sinfo = (void *)sinfo + total_record_size;
+ }
+
+ return 0;
+}
+
+static int btf_ext_parse_hdr(__u8 *data, __u32 data_size,
+ btf_print_fn_t err_log)
+{
+ const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+ __u32 meta_left, last_func_info_pos;
+ void *finfo;
+
+ if (data_size < offsetof(struct btf_ext_header, func_info_off) ||
+ data_size < hdr->hdr_len) {
+ elog("BTF.ext header not found");
+ return -EINVAL;
+ }
+
+ if (hdr->magic != BTF_MAGIC) {
+ elog("Invalid BTF.ext magic:%x\n", hdr->magic);
+ return -EINVAL;
+ }
+
+ if (hdr->version != BTF_VERSION) {
+ elog("Unsupported BTF.ext version:%u\n", hdr->version);
+ return -ENOTSUP;
+ }
+
+ if (hdr->flags) {
+ elog("Unsupported BTF.ext flags:%x\n", hdr->flags);
+ return -ENOTSUP;
+ }
+
+ meta_left = data_size - hdr->hdr_len;
+ if (!meta_left) {
+ elog("BTF.ext has no data\n");
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->func_info_off) {
+ elog("Invalid BTF.ext func_info section offset:%u\n",
+ hdr->func_info_off);
+ return -EINVAL;
+ }
+
+ if (hdr->func_info_off & 0x03) {
+ elog("BTF.ext func_info section is not aligned to 4 bytes\n");
+ return -EINVAL;
+ }
+
+ last_func_info_pos = hdr->hdr_len + hdr->func_info_off +
+ hdr->func_info_len;
+ if (last_func_info_pos > data_size) {
+ elog("Invalid BTF.ext func_info section size:%u\n",
+ hdr->func_info_len);
+ return -EINVAL;
+ }
+
+ finfo = data + hdr->hdr_len + hdr->func_info_off;
+ return btf_ext_validate_func_info(finfo, hdr->func_info_len,
+ err_log);
+}
+
+void btf_ext__free(struct btf_ext *btf_ext)
+{
+ if (!btf_ext)
+ return;
+
+ free(btf_ext->func_info);
+ free(btf_ext);
+}
+
+struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
+{
+ const struct btf_ext_header *hdr;
+ struct btf_ext *btf_ext;
+ void *org_fdata, *fdata;
+ __u32 hdrlen, size_u32;
+ int err;
+
+ err = btf_ext_parse_hdr(data, size, err_log);
+ if (err)
+ return ERR_PTR(err);
+
+ btf_ext = calloc(1, sizeof(struct btf_ext));
+ if (!btf_ext)
+ return ERR_PTR(-ENOMEM);
+
+ hdr = (const struct btf_ext_header *)data;
+ hdrlen = hdr->hdr_len;
+ size_u32 = sizeof(__u32);
+ fdata = malloc(hdr->func_info_len - size_u32);
+ if (!fdata) {
+ free(btf_ext);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* remember record size and copy rest of func_info data */
+ org_fdata = data + hdrlen + hdr->func_info_off;
+ btf_ext->func_info_rec_size = *(__u32 *)org_fdata;
+ memcpy(fdata, org_fdata + size_u32, hdr->func_info_len - size_u32);
+ btf_ext->func_info = fdata;
+ btf_ext->func_info_len = hdr->func_info_len - size_u32;
+
+ return btf_ext;
+}
+
+int btf_ext__reloc_init(struct btf *btf, struct btf_ext *btf_ext,
+ const char *sec_name, void **func_info,
+ __u32 *func_info_rec_size, __u32 *func_info_len)
+{
+ __u32 sec_hdrlen = sizeof(struct btf_sec_func_info);
+ __u32 i, record_size, records_len;
+ struct btf_sec_func_info *sinfo;
+ const char *info_sec_name;
+ __s64 remain_len;
+ void *data;
+
+ record_size = btf_ext->func_info_rec_size;
+ sinfo = btf_ext->func_info;
+ remain_len = btf_ext->func_info_len;
+
+ while (remain_len > 0) {
+ records_len = sinfo->num_func_info * record_size;
+ info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
+ if (strcmp(info_sec_name, sec_name)) {
+ remain_len -= sec_hdrlen + records_len;
+ sinfo = (void *)sinfo + sec_hdrlen + records_len;
+ continue;
+ }
+
+ data = malloc(records_len);
+ if (!data)
+ return -ENOMEM;
+
+ memcpy(data, sinfo->data, records_len);
+
+ /* adjust the insn_offset, the data in .BTF.ext is
+ * the actual byte offset, and the kernel expects
+ * the offset in term of bpf_insn.
+ *
+ * adjust the insn offset only, the rest data will
+ * be passed to kernel.
+ */
+ for (i = 0; i < sinfo->num_func_info; i++) {
+ struct bpf_func_info_min *record;
+
+ record = data + i * record_size;
+ record->insn_offset /= sizeof(struct bpf_insn);
+ }
+
+ *func_info = data;
+ *func_info_len = records_len;
+ *func_info_rec_size = record_size;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext,
+ const char *sec_name, __u32 insns_cnt,
+ void **func_info, __u32 *func_info_len)
+{
+ __u32 sec_hdrlen = sizeof(struct btf_sec_func_info);
+ __u32 i, record_size, existing_flen, records_len;
+ struct btf_sec_func_info *sinfo;
+ const char *info_sec_name;
+ __u64 remain_len;
+ void *data;
+
+ record_size = btf_ext->func_info_rec_size;
+ sinfo = btf_ext->func_info;
+ remain_len = btf_ext->func_info_len;
+ while (remain_len > 0) {
+ records_len = sinfo->num_func_info * record_size;
+ info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
+ if (strcmp(info_sec_name, sec_name)) {
+ remain_len -= sec_hdrlen + records_len;
+ sinfo = (void *)sinfo + sec_hdrlen + records_len;
+ continue;
+ }
+
+ existing_flen = *func_info_len;
+ data = realloc(*func_info, existing_flen + records_len);
+ if (!data)
+ return -ENOMEM;
+
+ memcpy(data + existing_flen, sinfo->data, records_len);
+ /* adjust insn_offset only, the rest data will be passed
+ * to the kernel.
+ */
+ for (i = 0; i < sinfo->num_func_info; i++) {
+ struct bpf_func_info_min *record;
+
+ record = data + existing_flen + i * record_size;
+ record->insn_offset =
+ record->insn_offset / sizeof(struct bpf_insn) +
+ insns_cnt;
+ }
+ *func_info = data;
+ *func_info_len = existing_flen + records_len;
+ return 0;
+ }
+
+ return -EINVAL;
+}
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index b77e7080f7e7..578171e8cb26 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -11,10 +11,51 @@
#endif
#define BTF_ELF_SEC ".BTF"
+#define BTF_EXT_ELF_SEC ".BTF.ext"
struct btf;
+struct btf_ext;
struct btf_type;
+/*
+ * The .BTF.ext ELF section layout defined as
+ * struct btf_ext_header
+ * func_info subsection
+ *
+ * The func_info subsection layout:
+ * record size for struct bpf_func_info in the func_info subsection
+ * struct btf_sec_func_info for section #1
+ * a list of bpf_func_info records for section #1
+ * where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
+ * but may not be identical
+ * struct btf_sec_func_info for section #2
+ * a list of bpf_func_info records for section #2
+ * ......
+ *
+ * Note that the bpf_func_info record size in .BTF.ext may not
+ * be the same as the one defined in include/uapi/linux/bpf.h.
+ * The loader should ensure that record_size meets minimum
+ * requirement and pass the record as is to the kernel. The
+ * kernel will handle the func_info properly based on its contents.
+ */
+struct btf_ext_header {
+ __u16 magic;
+ __u8 version;
+ __u8 flags;
+ __u32 hdr_len;
+
+ /* All offsets are in bytes relative to the end of this header */
+ __u32 func_info_off;
+ __u32 func_info_len;
+};
+
+struct btf_sec_func_info {
+ __u32 sec_name_off;
+ __u32 num_func_info;
+ /* Followed by num_func_info number of bpf func_info records */
+ __u8 data[0];
+};
+
typedef int (*btf_print_fn_t)(const char *, ...)
__attribute__((format(printf, 1, 2)));
@@ -29,4 +70,13 @@ LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
LIBBPF_API int btf__fd(const struct btf *btf);
LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
+struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
+void btf_ext__free(struct btf_ext *btf_ext);
+int btf_ext__reloc_init(struct btf *btf, struct btf_ext *btf_ext,
+ const char *sec_name, void **func_info,
+ __u32 *func_info_rec_size, __u32 *func_info_len);
+int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext,
+ const char *sec_name, __u32 insns_cnt, void **func_info,
+ __u32 *func_info_len);
+
#endif /* __LIBBPF_BTF_H */
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a01eb9584e52..cb6565d79603 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -156,6 +156,10 @@ struct bpf_program {
bpf_program_clear_priv_t clear_priv;
enum bpf_attach_type expected_attach_type;
+ int btf_fd;
+ void *func_info;
+ __u32 func_info_rec_size;
+ __u32 func_info_len;
};
struct bpf_map {
@@ -212,6 +216,7 @@ struct bpf_object {
struct list_head list;
struct btf *btf;
+ struct btf_ext *btf_ext;
void *priv;
bpf_object_clear_priv_t clear_priv;
@@ -241,6 +246,9 @@ void bpf_program__unload(struct bpf_program *prog)
prog->instances.nr = -1;
zfree(&prog->instances.fds);
+
+ zclose(prog->btf_fd);
+ zfree(&prog->func_info);
}
static void bpf_program__exit(struct bpf_program *prog)
@@ -315,6 +323,7 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx,
prog->instances.fds = NULL;
prog->instances.nr = -1;
prog->type = BPF_PROG_TYPE_KPROBE;
+ prog->btf_fd = -1;
return 0;
errout:
@@ -807,6 +816,15 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
BTF_ELF_SEC, PTR_ERR(obj->btf));
obj->btf = NULL;
}
+ } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+ obj->btf_ext = btf_ext__new(data->d_buf, data->d_size,
+ __pr_debug);
+ if (IS_ERR(obj->btf_ext)) {
+ pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
+ BTF_EXT_ELF_SEC,
+ PTR_ERR(obj->btf_ext));
+ obj->btf_ext = NULL;
+ }
} else if (sh.sh_type == SHT_SYMTAB) {
if (obj->efile.symbols) {
pr_warning("bpf: multiple SYMTAB in %s\n",
@@ -1190,6 +1208,7 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
struct bpf_insn *insn, *new_insn;
struct bpf_program *text;
size_t new_cnt;
+ int err;
if (relo->type != RELO_CALL)
return -LIBBPF_ERRNO__RELOC;
@@ -1212,6 +1231,20 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
pr_warning("oom in prog realloc\n");
return -ENOMEM;
}
+
+ if (obj->btf && obj->btf_ext) {
+ err = btf_ext__reloc(obj->btf, obj->btf_ext,
+ text->section_name,
+ prog->insns_cnt,
+ &prog->func_info,
+ &prog->func_info_len);
+ if (err) {
+ pr_warning("error in btf_ext__reloc for sec %s\n",
+ text->section_name);
+ return err;
+ }
+ }
+
memcpy(new_insn + prog->insns_cnt, text->insns,
text->insns_cnt * sizeof(*insn));
prog->insns = new_insn;
@@ -1231,7 +1264,24 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
{
int i, err;
- if (!prog || !prog->reloc_desc)
+ if (!prog)
+ return 0;
+
+ if (obj->btf && obj->btf_ext) {
+ err = btf_ext__reloc_init(obj->btf, obj->btf_ext,
+ prog->section_name,
+ &prog->func_info,
+ &prog->func_info_rec_size,
+ &prog->func_info_len);
+ if (err) {
+ pr_warning("err in btf_ext__reloc_init for sec %s\n",
+ prog->section_name);
+ return err;
+ }
+ prog->btf_fd = btf__fd(obj->btf);
+ }
+
+ if (!prog->reloc_desc)
return 0;
for (i = 0; i < prog->nr_reloc; i++) {
@@ -1319,9 +1369,9 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
}
static int
-load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type,
- const char *name, struct bpf_insn *insns, int insns_cnt,
- char *license, __u32 kern_version, int *pfd, int prog_ifindex)
+load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
+ char *license, __u32 kern_version, int *pfd,
+ __u32 func_info_cnt)
{
struct bpf_load_program_attr load_attr;
char *cp, errmsg[STRERR_BUFSIZE];
@@ -1329,14 +1379,18 @@ load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type,
int ret;
memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
- load_attr.prog_type = type;
- load_attr.expected_attach_type = expected_attach_type;
- load_attr.name = name;
+ load_attr.prog_type = prog->type;
+ load_attr.expected_attach_type = prog->expected_attach_type;
+ load_attr.name = prog->name;
load_attr.insns = insns;
load_attr.insns_cnt = insns_cnt;
load_attr.license = license;
load_attr.kern_version = kern_version;
- load_attr.prog_ifindex = prog_ifindex;
+ load_attr.prog_ifindex = prog->prog_ifindex;
+ load_attr.prog_btf_fd = prog->btf_fd;
+ load_attr.func_info = prog->func_info;
+ load_attr.func_info_rec_size = prog->func_info_rec_size;
+ load_attr.func_info_cnt = func_info_cnt;
if (!load_attr.insns || !load_attr.insns_cnt)
return -EINVAL;
@@ -1394,8 +1448,14 @@ int
bpf_program__load(struct bpf_program *prog,
char *license, __u32 kern_version)
{
+ __u32 func_info_cnt;
int err = 0, fd, i;
+ if (prog->func_info_len == 0)
+ func_info_cnt = 0;
+ else
+ func_info_cnt = prog->func_info_len / prog->func_info_rec_size;
+
if (prog->instances.nr < 0 || !prog->instances.fds) {
if (prog->preprocessor) {
pr_warning("Internal error: can't load program '%s'\n",
@@ -1417,10 +1477,9 @@ bpf_program__load(struct bpf_program *prog,
pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n",
prog->section_name, prog->instances.nr);
}
- err = load_program(prog->type, prog->expected_attach_type,
- prog->name, prog->insns, prog->insns_cnt,
+ err = load_program(prog, prog->insns, prog->insns_cnt,
license, kern_version, &fd,
- prog->prog_ifindex);
+ func_info_cnt);
if (!err)
prog->instances.fds[0] = fd;
goto out;
@@ -1448,11 +1507,10 @@ bpf_program__load(struct bpf_program *prog,
continue;
}
- err = load_program(prog->type, prog->expected_attach_type,
- prog->name, result.new_insn_ptr,
+ err = load_program(prog, result.new_insn_ptr,
result.new_insn_cnt,
license, kern_version, &fd,
- prog->prog_ifindex);
+ func_info_cnt);
if (err) {
pr_warning("Loading the %dth instance of program '%s' failed\n",
@@ -2120,6 +2178,7 @@ void bpf_object__close(struct bpf_object *obj)
bpf_object__elf_finish(obj);
bpf_object__unload(obj);
btf__free(obj->btf);
+ btf_ext__free(obj->btf_ext);
for (i = 0; i < obj->nr_maps; i++) {
zfree(&obj->maps[i].name);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.