summaryrefslogtreecommitdiffstats
path: root/tools/lib/bpf/btf.c
diff options
context:
space:
mode:
Diffstat (limited to 'tools/lib/bpf/btf.c')
-rw-r--r--tools/lib/bpf/btf.c373
1 files changed, 373 insertions, 0 deletions
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
new file mode 100644
index 000000000000..8c54a4b6f187
--- /dev/null
+++ b/tools/lib/bpf/btf.c
@@ -0,0 +1,373 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include "btf.h"
+#include "bpf.h"
+
+#define elog(fmt, ...) { if (err_log) err_log(fmt, ##__VA_ARGS__); }
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+#define BTF_MAX_NR_TYPES 65535
+
+static struct btf_type btf_void;
+
+struct btf {
+ union {
+ struct btf_header *hdr;
+ void *data;
+ };
+ struct btf_type **types;
+ const char *strings;
+ void *nohdr_data;
+ uint32_t nr_types;
+ uint32_t types_size;
+ uint32_t data_size;
+ int fd;
+};
+
+static const char *btf_name_by_offset(const struct btf *btf, uint32_t offset)
+{
+ if (offset < btf->hdr->str_len)
+ return &btf->strings[offset];
+ else
+ return NULL;
+}
+
+static int btf_add_type(struct btf *btf, struct btf_type *t)
+{
+ if (btf->types_size - btf->nr_types < 2) {
+ struct btf_type **new_types;
+ u32 expand_by, new_size;
+
+ if (btf->types_size == BTF_MAX_NR_TYPES)
+ return -E2BIG;
+
+ expand_by = max(btf->types_size >> 2, 16);
+ new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
+
+ new_types = realloc(btf->types, sizeof(*new_types) * new_size);
+ if (!new_types)
+ return -ENOMEM;
+
+ if (btf->nr_types == 0)
+ new_types[0] = &btf_void;
+
+ btf->types = new_types;
+ btf->types_size = new_size;
+ }
+
+ btf->types[++(btf->nr_types)] = t;
+
+ return 0;
+}
+
+static int btf_parse_hdr(struct btf *btf, btf_print_fn_t err_log)
+{
+ const struct btf_header *hdr = btf->hdr;
+ u32 meta_left;
+
+ if (btf->data_size < sizeof(struct btf_header)) {
+ elog("BTF header not found\n");
+ return -EINVAL;
+ }
+
+ if (hdr->magic != BTF_MAGIC) {
+ elog("Invalid BTF magic:%x\n", hdr->magic);
+ return -EINVAL;
+ }
+
+ if (hdr->version != BTF_VERSION) {
+ elog("Unsupported BTF version:%u\n", hdr->version);
+ return -ENOTSUP;
+ }
+
+ if (hdr->flags) {
+ elog("Unsupported BTF flags:%x\n", hdr->flags);
+ return -ENOTSUP;
+ }
+
+ meta_left = btf->data_size - sizeof(*hdr);
+ if (!meta_left) {
+ elog("BTF has no data\n");
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->type_off) {
+ elog("Invalid BTF type section offset:%u\n", hdr->type_off);
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->str_off) {
+ elog("Invalid BTF string section offset:%u\n", hdr->str_off);
+ return -EINVAL;
+ }
+
+ if (hdr->type_off >= hdr->str_off) {
+ elog("BTF type section offset >= string section offset. No type?\n");
+ return -EINVAL;
+ }
+
+ if (hdr->type_off & 0x02) {
+ elog("BTF type section is not aligned to 4 bytes\n");
+ return -EINVAL;
+ }
+
+ btf->nohdr_data = btf->hdr + 1;
+
+ return 0;
+}
+
+static int btf_parse_str_sec(struct btf *btf, btf_print_fn_t err_log)
+{
+ const struct btf_header *hdr = btf->hdr;
+ const char *start = btf->nohdr_data + hdr->str_off;
+ const char *end = start + btf->hdr->str_len;
+
+ if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
+ start[0] || end[-1]) {
+ elog("Invalid BTF string section\n");
+ return -EINVAL;
+ }
+
+ btf->strings = start;
+
+ return 0;
+}
+
+static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
+{
+ struct btf_header *hdr = btf->hdr;
+ void *nohdr_data = btf->nohdr_data;
+ void *next_type = nohdr_data + hdr->type_off;
+ void *end_type = nohdr_data + hdr->str_off;
+
+ while (next_type < end_type) {
+ struct btf_type *t = next_type;
+ uint16_t vlen = BTF_INFO_VLEN(t->info);
+ int err;
+
+ next_type += sizeof(*t);
+ switch (BTF_INFO_KIND(t->info)) {
+ case BTF_KIND_INT:
+ next_type += sizeof(int);
+ break;
+ case BTF_KIND_ARRAY:
+ next_type += sizeof(struct btf_array);
+ break;
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ next_type += vlen * sizeof(struct btf_member);
+ break;
+ case BTF_KIND_ENUM:
+ next_type += vlen * sizeof(struct btf_enum);
+ break;
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_PTR:
+ case BTF_KIND_FWD:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ break;
+ default:
+ elog("Unsupported BTF_KIND:%u\n",
+ BTF_INFO_KIND(t->info));
+ return -EINVAL;
+ }
+
+ err = btf_add_type(btf, t);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static const struct btf_type *btf_type_by_id(const struct btf *btf,
+ uint32_t type_id)
+{
+ if (type_id > btf->nr_types)
+ return NULL;
+
+ return btf->types[type_id];
+}
+
+static bool btf_type_is_void(const struct btf_type *t)
+{
+ return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+ return !t || btf_type_is_void(t);
+}
+
+static int64_t btf_type_size(const struct btf_type *t)
+{
+ switch (BTF_INFO_KIND(t->info)) {
+ case BTF_KIND_INT:
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ case BTF_KIND_ENUM:
+ return t->size;
+ case BTF_KIND_PTR:
+ return sizeof(void *);
+ default:
+ return -EINVAL;
+ }
+}
+
+#define MAX_RESOLVE_DEPTH 32
+
+int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id)
+{
+ const struct btf_array *array;
+ const struct btf_type *t;
+ uint32_t nelems = 1;
+ int64_t size = -1;
+ int i;
+
+ t = btf_type_by_id(btf, type_id);
+ for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
+ i++) {
+ size = btf_type_size(t);
+ if (size >= 0)
+ break;
+
+ switch (BTF_INFO_KIND(t->info)) {
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ type_id = t->type;
+ break;
+ case BTF_KIND_ARRAY:
+ array = (const struct btf_array *)(t + 1);
+ if (nelems && array->nelems > UINT32_MAX / nelems)
+ return -E2BIG;
+ nelems *= array->nelems;
+ type_id = array->type;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ t = btf_type_by_id(btf, type_id);
+ }
+
+ if (size < 0)
+ return -EINVAL;
+
+ if (nelems && size > UINT32_MAX / nelems)
+ return -E2BIG;
+
+ return nelems * size;
+}
+
+int32_t btf__find_by_name(const struct btf *btf, const char *type_name)
+{
+ uint32_t i;
+
+ if (!strcmp(type_name, "void"))
+ return 0;
+
+ for (i = 1; i <= btf->nr_types; i++) {
+ const struct btf_type *t = btf->types[i];
+ const char *name = btf_name_by_offset(btf, t->name_off);
+
+ if (name && !strcmp(type_name, name))
+ return i;
+ }
+
+ return -ENOENT;
+}
+
+void btf__free(struct btf *btf)
+{
+ if (!btf)
+ return;
+
+ if (btf->fd != -1)
+ close(btf->fd);
+
+ free(btf->data);
+ free(btf->types);
+ free(btf);
+}
+
+struct btf *btf__new(uint8_t *data, uint32_t size,
+ btf_print_fn_t err_log)
+{
+ uint32_t log_buf_size = 0;
+ char *log_buf = NULL;
+ struct btf *btf;
+ int err;
+
+ btf = calloc(1, sizeof(struct btf));
+ if (!btf)
+ return ERR_PTR(-ENOMEM);
+
+ btf->fd = -1;
+
+ if (err_log) {
+ log_buf = malloc(BPF_LOG_BUF_SIZE);
+ if (!log_buf) {
+ err = -ENOMEM;
+ goto done;
+ }
+ *log_buf = 0;
+ log_buf_size = BPF_LOG_BUF_SIZE;
+ }
+
+ btf->data = malloc(size);
+ if (!btf->data) {
+ err = -ENOMEM;
+ goto done;
+ }
+
+ memcpy(btf->data, data, size);
+ btf->data_size = size;
+
+ btf->fd = bpf_load_btf(btf->data, btf->data_size,
+ log_buf, log_buf_size, false);
+
+ if (btf->fd == -1) {
+ err = -errno;
+ elog("Error loading BTF: %s(%d)\n", strerror(errno), errno);
+ if (log_buf && *log_buf)
+ elog("%s\n", log_buf);
+ goto done;
+ }
+
+ err = btf_parse_hdr(btf, err_log);
+ if (err)
+ goto done;
+
+ err = btf_parse_str_sec(btf, err_log);
+ if (err)
+ goto done;
+
+ err = btf_parse_type_sec(btf, err_log);
+
+done:
+ free(log_buf);
+
+ if (err) {
+ btf__free(btf);
+ return ERR_PTR(err);
+ }
+
+ return btf;
+}
+
+int btf__fd(const struct btf *btf)
+{
+ return btf->fd;
+}