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-rw-r--r--src/contrib/libbpf/bpf/btf.c2884
1 files changed, 2884 insertions, 0 deletions
diff --git a/src/contrib/libbpf/bpf/btf.c b/src/contrib/libbpf/bpf/btf.c
new file mode 100644
index 0000000..88efa2b
--- /dev/null
+++ b/src/contrib/libbpf/bpf/btf.c
@@ -0,0 +1,2884 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <endian.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include <gelf.h>
+#include "btf.h"
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+
+#define BTF_MAX_NR_TYPES 0x7fffffff
+#define BTF_MAX_STR_OFFSET 0x7fffffff
+
+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;
+ __u32 nr_types;
+ __u32 types_size;
+ __u32 data_size;
+ int fd;
+};
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+ return (__u64) (unsigned long) ptr;
+}
+
+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)
+{
+ const struct btf_header *hdr = btf->hdr;
+ __u32 meta_left;
+
+ if (btf->data_size < sizeof(struct btf_header)) {
+ pr_debug("BTF header not found\n");
+ return -EINVAL;
+ }
+
+ if (hdr->magic != BTF_MAGIC) {
+ pr_debug("Invalid BTF magic:%x\n", hdr->magic);
+ return -EINVAL;
+ }
+
+ if (hdr->version != BTF_VERSION) {
+ pr_debug("Unsupported BTF version:%u\n", hdr->version);
+ return -ENOTSUP;
+ }
+
+ if (hdr->flags) {
+ pr_debug("Unsupported BTF flags:%x\n", hdr->flags);
+ return -ENOTSUP;
+ }
+
+ meta_left = btf->data_size - sizeof(*hdr);
+ if (!meta_left) {
+ pr_debug("BTF has no data\n");
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->type_off) {
+ pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->str_off) {
+ pr_debug("Invalid BTF string section offset:%u\n", hdr->str_off);
+ return -EINVAL;
+ }
+
+ if (hdr->type_off >= hdr->str_off) {
+ pr_debug("BTF type section offset >= string section offset. No type?\n");
+ return -EINVAL;
+ }
+
+ if (hdr->type_off & 0x02) {
+ pr_debug("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)
+{
+ 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_STR_OFFSET ||
+ start[0] || end[-1]) {
+ pr_debug("Invalid BTF string section\n");
+ return -EINVAL;
+ }
+
+ btf->strings = start;
+
+ return 0;
+}
+
+static int btf_type_size(struct btf_type *t)
+{
+ int base_size = sizeof(struct btf_type);
+ __u16 vlen = btf_vlen(t);
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_FWD:
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ return base_size;
+ case BTF_KIND_INT:
+ return base_size + sizeof(__u32);
+ case BTF_KIND_ENUM:
+ return base_size + vlen * sizeof(struct btf_enum);
+ case BTF_KIND_ARRAY:
+ return base_size + sizeof(struct btf_array);
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ return base_size + vlen * sizeof(struct btf_member);
+ case BTF_KIND_FUNC_PROTO:
+ return base_size + vlen * sizeof(struct btf_param);
+ case BTF_KIND_VAR:
+ return base_size + sizeof(struct btf_var);
+ case BTF_KIND_DATASEC:
+ return base_size + vlen * sizeof(struct btf_var_secinfo);
+ default:
+ pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
+ return -EINVAL;
+ }
+}
+
+static int btf_parse_type_sec(struct btf *btf)
+{
+ 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;
+ int type_size;
+ int err;
+
+ type_size = btf_type_size(t);
+ if (type_size < 0)
+ return type_size;
+ next_type += type_size;
+ err = btf_add_type(btf, t);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+__u32 btf__get_nr_types(const struct btf *btf)
+{
+ return btf->nr_types;
+}
+
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 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_is_fwd(t);
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+ return !t || btf_type_is_void(t);
+}
+
+#define MAX_RESOLVE_DEPTH 32
+
+__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
+{
+ const struct btf_array *array;
+ const struct btf_type *t;
+ __u32 nelems = 1;
+ __s64 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++) {
+ switch (btf_kind(t)) {
+ case BTF_KIND_INT:
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ case BTF_KIND_ENUM:
+ case BTF_KIND_DATASEC:
+ size = t->size;
+ goto done;
+ case BTF_KIND_PTR:
+ size = sizeof(void *);
+ goto done;
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_VAR:
+ type_id = t->type;
+ break;
+ case BTF_KIND_ARRAY:
+ array = btf_array(t);
+ 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);
+ }
+
+done:
+ if (size < 0)
+ return -EINVAL;
+ if (nelems && size > UINT32_MAX / nelems)
+ return -E2BIG;
+
+ return nelems * size;
+}
+
+int btf__resolve_type(const struct btf *btf, __u32 type_id)
+{
+ const struct btf_type *t;
+ int depth = 0;
+
+ t = btf__type_by_id(btf, type_id);
+ while (depth < MAX_RESOLVE_DEPTH &&
+ !btf_type_is_void_or_null(t) &&
+ (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
+ type_id = t->type;
+ t = btf__type_by_id(btf, type_id);
+ depth++;
+ }
+
+ if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
+ return -EINVAL;
+
+ return type_id;
+}
+
+__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
+{
+ __u32 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;
+}
+
+__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
+ __u32 kind)
+{
+ __u32 i;
+
+ if (kind == BTF_KIND_UNKN || !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;
+
+ if (btf_kind(t) != kind)
+ continue;
+ 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(__u8 *data, __u32 size)
+{
+ struct btf *btf;
+ int err;
+
+ btf = calloc(1, sizeof(struct btf));
+ if (!btf)
+ return ERR_PTR(-ENOMEM);
+
+ btf->fd = -1;
+
+ btf->data = malloc(size);
+ if (!btf->data) {
+ err = -ENOMEM;
+ goto done;
+ }
+
+ memcpy(btf->data, data, size);
+ btf->data_size = size;
+
+ err = btf_parse_hdr(btf);
+ if (err)
+ goto done;
+
+ err = btf_parse_str_sec(btf);
+ if (err)
+ goto done;
+
+ err = btf_parse_type_sec(btf);
+
+done:
+ if (err) {
+ btf__free(btf);
+ return ERR_PTR(err);
+ }
+
+ return btf;
+}
+
+static bool btf_check_endianness(const GElf_Ehdr *ehdr)
+{
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+ return ehdr->e_ident[EI_DATA] == ELFDATA2LSB;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+ return ehdr->e_ident[EI_DATA] == ELFDATA2MSB;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+}
+
+struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
+{
+ Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
+ int err = 0, fd = -1, idx = 0;
+ struct btf *btf = NULL;
+ Elf_Scn *scn = NULL;
+ Elf *elf = NULL;
+ GElf_Ehdr ehdr;
+
+ if (elf_version(EV_CURRENT) == EV_NONE) {
+ pr_warn("failed to init libelf for %s\n", path);
+ return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+ }
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0) {
+ err = -errno;
+ pr_warn("failed to open %s: %s\n", path, strerror(errno));
+ return ERR_PTR(err);
+ }
+
+ err = -LIBBPF_ERRNO__FORMAT;
+
+ elf = elf_begin(fd, ELF_C_READ, NULL);
+ if (!elf) {
+ pr_warn("failed to open %s as ELF file\n", path);
+ goto done;
+ }
+ if (!gelf_getehdr(elf, &ehdr)) {
+ pr_warn("failed to get EHDR from %s\n", path);
+ goto done;
+ }
+ if (!btf_check_endianness(&ehdr)) {
+ pr_warn("non-native ELF endianness is not supported\n");
+ goto done;
+ }
+ if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
+ pr_warn("failed to get e_shstrndx from %s\n", path);
+ goto done;
+ }
+
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
+ GElf_Shdr sh;
+ char *name;
+
+ idx++;
+ if (gelf_getshdr(scn, &sh) != &sh) {
+ pr_warn("failed to get section(%d) header from %s\n",
+ idx, path);
+ goto done;
+ }
+ name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
+ if (!name) {
+ pr_warn("failed to get section(%d) name from %s\n",
+ idx, path);
+ goto done;
+ }
+ if (strcmp(name, BTF_ELF_SEC) == 0) {
+ btf_data = elf_getdata(scn, 0);
+ if (!btf_data) {
+ pr_warn("failed to get section(%d, %s) data from %s\n",
+ idx, name, path);
+ goto done;
+ }
+ continue;
+ } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+ btf_ext_data = elf_getdata(scn, 0);
+ if (!btf_ext_data) {
+ pr_warn("failed to get section(%d, %s) data from %s\n",
+ idx, name, path);
+ goto done;
+ }
+ continue;
+ }
+ }
+
+ err = 0;
+
+ if (!btf_data) {
+ err = -ENOENT;
+ goto done;
+ }
+ btf = btf__new(btf_data->d_buf, btf_data->d_size);
+ if (IS_ERR(btf))
+ goto done;
+
+ if (btf_ext && btf_ext_data) {
+ *btf_ext = btf_ext__new(btf_ext_data->d_buf,
+ btf_ext_data->d_size);
+ if (IS_ERR(*btf_ext))
+ goto done;
+ } else if (btf_ext) {
+ *btf_ext = NULL;
+ }
+done:
+ if (elf)
+ elf_end(elf);
+ close(fd);
+
+ if (err)
+ return ERR_PTR(err);
+ /*
+ * btf is always parsed before btf_ext, so no need to clean up
+ * btf_ext, if btf loading failed
+ */
+ if (IS_ERR(btf))
+ return btf;
+ if (btf_ext && IS_ERR(*btf_ext)) {
+ btf__free(btf);
+ err = PTR_ERR(*btf_ext);
+ return ERR_PTR(err);
+ }
+ return btf;
+}
+
+static int compare_vsi_off(const void *_a, const void *_b)
+{
+ const struct btf_var_secinfo *a = _a;
+ const struct btf_var_secinfo *b = _b;
+
+ return a->offset - b->offset;
+}
+
+static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
+ struct btf_type *t)
+{
+ __u32 size = 0, off = 0, i, vars = btf_vlen(t);
+ const char *name = btf__name_by_offset(btf, t->name_off);
+ const struct btf_type *t_var;
+ struct btf_var_secinfo *vsi;
+ const struct btf_var *var;
+ int ret;
+
+ if (!name) {
+ pr_debug("No name found in string section for DATASEC kind.\n");
+ return -ENOENT;
+ }
+
+ ret = bpf_object__section_size(obj, name, &size);
+ if (ret || !size || (t->size && t->size != size)) {
+ pr_debug("Invalid size for section %s: %u bytes\n", name, size);
+ return -ENOENT;
+ }
+
+ t->size = size;
+
+ for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
+ t_var = btf__type_by_id(btf, vsi->type);
+ var = btf_var(t_var);
+
+ if (!btf_is_var(t_var)) {
+ pr_debug("Non-VAR type seen in section %s\n", name);
+ return -EINVAL;
+ }
+
+ if (var->linkage == BTF_VAR_STATIC)
+ continue;
+
+ name = btf__name_by_offset(btf, t_var->name_off);
+ if (!name) {
+ pr_debug("No name found in string section for VAR kind\n");
+ return -ENOENT;
+ }
+
+ ret = bpf_object__variable_offset(obj, name, &off);
+ if (ret) {
+ pr_debug("No offset found in symbol table for VAR %s\n",
+ name);
+ return -ENOENT;
+ }
+
+ vsi->offset = off;
+ }
+
+ qsort(t + 1, vars, sizeof(*vsi), compare_vsi_off);
+ return 0;
+}
+
+int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
+{
+ int err = 0;
+ __u32 i;
+
+ for (i = 1; i <= btf->nr_types; i++) {
+ struct btf_type *t = btf->types[i];
+
+ /* Loader needs to fix up some of the things compiler
+ * couldn't get its hands on while emitting BTF. This
+ * is section size and global variable offset. We use
+ * the info from the ELF itself for this purpose.
+ */
+ if (btf_is_datasec(t)) {
+ err = btf_fixup_datasec(obj, btf, t);
+ if (err)
+ break;
+ }
+ }
+
+ return err;
+}
+
+int btf__load(struct btf *btf)
+{
+ __u32 log_buf_size = BPF_LOG_BUF_SIZE;
+ char *log_buf = NULL;
+ int err = 0;
+
+ if (btf->fd >= 0)
+ return -EEXIST;
+
+ log_buf = malloc(log_buf_size);
+ if (!log_buf)
+ return -ENOMEM;
+
+ *log_buf = 0;
+
+ btf->fd = bpf_load_btf(btf->data, btf->data_size,
+ log_buf, log_buf_size, false);
+ if (btf->fd < 0) {
+ err = -errno;
+ pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
+ if (*log_buf)
+ pr_warn("%s\n", log_buf);
+ goto done;
+ }
+
+done:
+ free(log_buf);
+ return err;
+}
+
+int btf__fd(const struct btf *btf)
+{
+ return btf->fd;
+}
+
+const void *btf__get_raw_data(const struct btf *btf, __u32 *size)
+{
+ *size = btf->data_size;
+ return btf->data;
+}
+
+const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
+{
+ if (offset < btf->hdr->str_len)
+ return &btf->strings[offset];
+ else
+ return NULL;
+}
+
+int btf__get_from_id(__u32 id, struct btf **btf)
+{
+ struct bpf_btf_info btf_info = { 0 };
+ __u32 len = sizeof(btf_info);
+ __u32 last_size;
+ int btf_fd;
+ void *ptr;
+ int err;
+
+ err = 0;
+ *btf = NULL;
+ btf_fd = bpf_btf_get_fd_by_id(id);
+ if (btf_fd < 0)
+ return 0;
+
+ /* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
+ * let's start with a sane default - 4KiB here - and resize it only if
+ * bpf_obj_get_info_by_fd() needs a bigger buffer.
+ */
+ btf_info.btf_size = 4096;
+ last_size = btf_info.btf_size;
+ ptr = malloc(last_size);
+ if (!ptr) {
+ err = -ENOMEM;
+ goto exit_free;
+ }
+
+ memset(ptr, 0, last_size);
+ btf_info.btf = ptr_to_u64(ptr);
+ err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+
+ if (!err && btf_info.btf_size > last_size) {
+ void *temp_ptr;
+
+ last_size = btf_info.btf_size;
+ temp_ptr = realloc(ptr, last_size);
+ if (!temp_ptr) {
+ err = -ENOMEM;
+ goto exit_free;
+ }
+ ptr = temp_ptr;
+ memset(ptr, 0, last_size);
+ btf_info.btf = ptr_to_u64(ptr);
+ err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+ }
+
+ if (err || btf_info.btf_size > last_size) {
+ err = errno;
+ goto exit_free;
+ }
+
+ *btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size);
+ if (IS_ERR(*btf)) {
+ err = PTR_ERR(*btf);
+ *btf = NULL;
+ }
+
+exit_free:
+ close(btf_fd);
+ free(ptr);
+
+ return err;
+}
+
+int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
+ __u32 expected_key_size, __u32 expected_value_size,
+ __u32 *key_type_id, __u32 *value_type_id)
+{
+ const struct btf_type *container_type;
+ const struct btf_member *key, *value;
+ const size_t max_name = 256;
+ char container_name[max_name];
+ __s64 key_size, value_size;
+ __s32 container_id;
+
+ if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
+ max_name) {
+ pr_warn("map:%s length of '____btf_map_%s' is too long\n",
+ map_name, map_name);
+ return -EINVAL;
+ }
+
+ container_id = btf__find_by_name(btf, container_name);
+ if (container_id < 0) {
+ pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
+ map_name, container_name);
+ return container_id;
+ }
+
+ container_type = btf__type_by_id(btf, container_id);
+ if (!container_type) {
+ pr_warn("map:%s cannot find BTF type for container_id:%u\n",
+ map_name, container_id);
+ return -EINVAL;
+ }
+
+ if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
+ pr_warn("map:%s container_name:%s is an invalid container struct\n",
+ map_name, container_name);
+ return -EINVAL;
+ }
+
+ key = btf_members(container_type);
+ value = key + 1;
+
+ key_size = btf__resolve_size(btf, key->type);
+ if (key_size < 0) {
+ pr_warn("map:%s invalid BTF key_type_size\n", map_name);
+ return key_size;
+ }
+
+ if (expected_key_size != key_size) {
+ pr_warn("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
+ map_name, (__u32)key_size, expected_key_size);
+ return -EINVAL;
+ }
+
+ value_size = btf__resolve_size(btf, value->type);
+ if (value_size < 0) {
+ pr_warn("map:%s invalid BTF value_type_size\n", map_name);
+ return value_size;
+ }
+
+ if (expected_value_size != value_size) {
+ pr_warn("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
+ map_name, (__u32)value_size, expected_value_size);
+ return -EINVAL;
+ }
+
+ *key_type_id = key->type;
+ *value_type_id = value->type;
+
+ return 0;
+}
+
+struct btf_ext_sec_setup_param {
+ __u32 off;
+ __u32 len;
+ __u32 min_rec_size;
+ struct btf_ext_info *ext_info;
+ const char *desc;
+};
+
+static int btf_ext_setup_info(struct btf_ext *btf_ext,
+ struct btf_ext_sec_setup_param *ext_sec)
+{
+ const struct btf_ext_info_sec *sinfo;
+ struct btf_ext_info *ext_info;
+ __u32 info_left, record_size;
+ /* The start of the info sec (including the __u32 record_size). */
+ void *info;
+
+ if (ext_sec->len == 0)
+ return 0;
+
+ if (ext_sec->off & 0x03) {
+ pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
+ info_left = ext_sec->len;
+
+ if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
+ pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
+ ext_sec->desc, ext_sec->off, ext_sec->len);
+ return -EINVAL;
+ }
+
+ /* At least a record size */
+ if (info_left < sizeof(__u32)) {
+ pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
+ return -EINVAL;
+ }
+
+ /* The record size needs to meet the minimum standard */
+ record_size = *(__u32 *)info;
+ if (record_size < ext_sec->min_rec_size ||
+ record_size & 0x03) {
+ pr_debug("%s section in .BTF.ext has invalid record size %u\n",
+ ext_sec->desc, record_size);
+ return -EINVAL;
+ }
+
+ sinfo = info + sizeof(__u32);
+ info_left -= sizeof(__u32);
+
+ /* If no records, return failure now so .BTF.ext won't be used. */
+ if (!info_left) {
+ pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
+ return -EINVAL;
+ }
+
+ while (info_left) {
+ unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
+ __u64 total_record_size;
+ __u32 num_records;
+
+ if (info_left < sec_hdrlen) {
+ pr_debug("%s section header is not found in .BTF.ext\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ num_records = sinfo->num_info;
+ if (num_records == 0) {
+ pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ total_record_size = sec_hdrlen +
+ (__u64)num_records * record_size;
+ if (info_left < total_record_size) {
+ pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ info_left -= total_record_size;
+ sinfo = (void *)sinfo + total_record_size;
+ }
+
+ ext_info = ext_sec->ext_info;
+ ext_info->len = ext_sec->len - sizeof(__u32);
+ ext_info->rec_size = record_size;
+ ext_info->info = info + sizeof(__u32);
+
+ return 0;
+}
+
+static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
+{
+ struct btf_ext_sec_setup_param param = {
+ .off = btf_ext->hdr->func_info_off,
+ .len = btf_ext->hdr->func_info_len,
+ .min_rec_size = sizeof(struct bpf_func_info_min),
+ .ext_info = &btf_ext->func_info,
+ .desc = "func_info"
+ };
+
+ return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
+{
+ struct btf_ext_sec_setup_param param = {
+ .off = btf_ext->hdr->line_info_off,
+ .len = btf_ext->hdr->line_info_len,
+ .min_rec_size = sizeof(struct bpf_line_info_min),
+ .ext_info = &btf_ext->line_info,
+ .desc = "line_info",
+ };
+
+ return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_field_reloc(struct btf_ext *btf_ext)
+{
+ struct btf_ext_sec_setup_param param = {
+ .off = btf_ext->hdr->field_reloc_off,
+ .len = btf_ext->hdr->field_reloc_len,
+ .min_rec_size = sizeof(struct bpf_field_reloc),
+ .ext_info = &btf_ext->field_reloc_info,
+ .desc = "field_reloc",
+ };
+
+ return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
+{
+ const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+
+ if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
+ data_size < hdr->hdr_len) {
+ pr_debug("BTF.ext header not found");
+ return -EINVAL;
+ }
+
+ if (hdr->magic != BTF_MAGIC) {
+ pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
+ return -EINVAL;
+ }
+
+ if (hdr->version != BTF_VERSION) {
+ pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
+ return -ENOTSUP;
+ }
+
+ if (hdr->flags) {
+ pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
+ return -ENOTSUP;
+ }
+
+ if (data_size == hdr->hdr_len) {
+ pr_debug("BTF.ext has no data\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+void btf_ext__free(struct btf_ext *btf_ext)
+{
+ if (!btf_ext)
+ return;
+ free(btf_ext->data);
+ free(btf_ext);
+}
+
+struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
+{
+ struct btf_ext *btf_ext;
+ int err;
+
+ err = btf_ext_parse_hdr(data, size);
+ if (err)
+ return ERR_PTR(err);
+
+ btf_ext = calloc(1, sizeof(struct btf_ext));
+ if (!btf_ext)
+ return ERR_PTR(-ENOMEM);
+
+ btf_ext->data_size = size;
+ btf_ext->data = malloc(size);
+ if (!btf_ext->data) {
+ err = -ENOMEM;
+ goto done;
+ }
+ memcpy(btf_ext->data, data, size);
+
+ if (btf_ext->hdr->hdr_len <
+ offsetofend(struct btf_ext_header, line_info_len))
+ goto done;
+ err = btf_ext_setup_func_info(btf_ext);
+ if (err)
+ goto done;
+
+ err = btf_ext_setup_line_info(btf_ext);
+ if (err)
+ goto done;
+
+ if (btf_ext->hdr->hdr_len <
+ offsetofend(struct btf_ext_header, field_reloc_len))
+ goto done;
+ err = btf_ext_setup_field_reloc(btf_ext);
+ if (err)
+ goto done;
+
+done:
+ if (err) {
+ btf_ext__free(btf_ext);
+ return ERR_PTR(err);
+ }
+
+ return btf_ext;
+}
+
+const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
+{
+ *size = btf_ext->data_size;
+ return btf_ext->data;
+}
+
+static int btf_ext_reloc_info(const struct btf *btf,
+ const struct btf_ext_info *ext_info,
+ const char *sec_name, __u32 insns_cnt,
+ void **info, __u32 *cnt)
+{
+ __u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
+ __u32 i, record_size, existing_len, records_len;
+ struct btf_ext_info_sec *sinfo;
+ const char *info_sec_name;
+ __u64 remain_len;
+ void *data;
+
+ record_size = ext_info->rec_size;
+ sinfo = ext_info->info;
+ remain_len = ext_info->len;
+ while (remain_len > 0) {
+ records_len = sinfo->num_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_len = (*cnt) * record_size;
+ data = realloc(*info, existing_len + records_len);
+ if (!data)
+ return -ENOMEM;
+
+ memcpy(data + existing_len, sinfo->data, records_len);
+ /* adjust insn_off only, the rest data will be passed
+ * to the kernel.
+ */
+ for (i = 0; i < sinfo->num_info; i++) {
+ __u32 *insn_off;
+
+ insn_off = data + existing_len + (i * record_size);
+ *insn_off = *insn_off / sizeof(struct bpf_insn) +
+ insns_cnt;
+ }
+ *info = data;
+ *cnt += sinfo->num_info;
+ return 0;
+ }
+
+ return -ENOENT;
+}
+
+int btf_ext__reloc_func_info(const struct btf *btf,
+ const struct btf_ext *btf_ext,
+ const char *sec_name, __u32 insns_cnt,
+ void **func_info, __u32 *cnt)
+{
+ return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
+ insns_cnt, func_info, cnt);
+}
+
+int btf_ext__reloc_line_info(const struct btf *btf,
+ const struct btf_ext *btf_ext,
+ const char *sec_name, __u32 insns_cnt,
+ void **line_info, __u32 *cnt)
+{
+ return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
+ insns_cnt, line_info, cnt);
+}
+
+__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
+{
+ return btf_ext->func_info.rec_size;
+}
+
+__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
+{
+ return btf_ext->line_info.rec_size;
+}
+
+struct btf_dedup;
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
+ const struct btf_dedup_opts *opts);
+static void btf_dedup_free(struct btf_dedup *d);
+static int btf_dedup_strings(struct btf_dedup *d);
+static int btf_dedup_prim_types(struct btf_dedup *d);
+static int btf_dedup_struct_types(struct btf_dedup *d);
+static int btf_dedup_ref_types(struct btf_dedup *d);
+static int btf_dedup_compact_types(struct btf_dedup *d);
+static int btf_dedup_remap_types(struct btf_dedup *d);
+
+/*
+ * Deduplicate BTF types and strings.
+ *
+ * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
+ * section with all BTF type descriptors and string data. It overwrites that
+ * memory in-place with deduplicated types and strings without any loss of
+ * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
+ * is provided, all the strings referenced from .BTF.ext section are honored
+ * and updated to point to the right offsets after deduplication.
+ *
+ * If function returns with error, type/string data might be garbled and should
+ * be discarded.
+ *
+ * More verbose and detailed description of both problem btf_dedup is solving,
+ * as well as solution could be found at:
+ * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
+ *
+ * Problem description and justification
+ * =====================================
+ *
+ * BTF type information is typically emitted either as a result of conversion
+ * from DWARF to BTF or directly by compiler. In both cases, each compilation
+ * unit contains information about a subset of all the types that are used
+ * in an application. These subsets are frequently overlapping and contain a lot
+ * of duplicated information when later concatenated together into a single
+ * binary. This algorithm ensures that each unique type is represented by single
+ * BTF type descriptor, greatly reducing resulting size of BTF data.
+ *
+ * Compilation unit isolation and subsequent duplication of data is not the only
+ * problem. The same type hierarchy (e.g., struct and all the type that struct
+ * references) in different compilation units can be represented in BTF to
+ * various degrees of completeness (or, rather, incompleteness) due to
+ * struct/union forward declarations.
+ *
+ * Let's take a look at an example, that we'll use to better understand the
+ * problem (and solution). Suppose we have two compilation units, each using
+ * same `struct S`, but each of them having incomplete type information about
+ * struct's fields:
+ *
+ * // CU #1:
+ * struct S;
+ * struct A {
+ * int a;
+ * struct A* self;
+ * struct S* parent;
+ * };
+ * struct B;
+ * struct S {
+ * struct A* a_ptr;
+ * struct B* b_ptr;
+ * };
+ *
+ * // CU #2:
+ * struct S;
+ * struct A;
+ * struct B {
+ * int b;
+ * struct B* self;
+ * struct S* parent;
+ * };
+ * struct S {
+ * struct A* a_ptr;
+ * struct B* b_ptr;
+ * };
+ *
+ * In case of CU #1, BTF data will know only that `struct B` exist (but no
+ * more), but will know the complete type information about `struct A`. While
+ * for CU #2, it will know full type information about `struct B`, but will
+ * only know about forward declaration of `struct A` (in BTF terms, it will
+ * have `BTF_KIND_FWD` type descriptor with name `B`).
+ *
+ * This compilation unit isolation means that it's possible that there is no
+ * single CU with complete type information describing structs `S`, `A`, and
+ * `B`. Also, we might get tons of duplicated and redundant type information.
+ *
+ * Additional complication we need to keep in mind comes from the fact that
+ * types, in general, can form graphs containing cycles, not just DAGs.
+ *
+ * While algorithm does deduplication, it also merges and resolves type
+ * information (unless disabled throught `struct btf_opts`), whenever possible.
+ * E.g., in the example above with two compilation units having partial type
+ * information for structs `A` and `B`, the output of algorithm will emit
+ * a single copy of each BTF type that describes structs `A`, `B`, and `S`
+ * (as well as type information for `int` and pointers), as if they were defined
+ * in a single compilation unit as:
+ *
+ * struct A {
+ * int a;
+ * struct A* self;
+ * struct S* parent;
+ * };
+ * struct B {
+ * int b;
+ * struct B* self;
+ * struct S* parent;
+ * };
+ * struct S {
+ * struct A* a_ptr;
+ * struct B* b_ptr;
+ * };
+ *
+ * Algorithm summary
+ * =================
+ *
+ * Algorithm completes its work in 6 separate passes:
+ *
+ * 1. Strings deduplication.
+ * 2. Primitive types deduplication (int, enum, fwd).
+ * 3. Struct/union types deduplication.
+ * 4. Reference types deduplication (pointers, typedefs, arrays, funcs, func
+ * protos, and const/volatile/restrict modifiers).
+ * 5. Types compaction.
+ * 6. Types remapping.
+ *
+ * Algorithm determines canonical type descriptor, which is a single
+ * representative type for each truly unique type. This canonical type is the
+ * one that will go into final deduplicated BTF type information. For
+ * struct/unions, it is also the type that algorithm will merge additional type
+ * information into (while resolving FWDs), as it discovers it from data in
+ * other CUs. Each input BTF type eventually gets either mapped to itself, if
+ * that type is canonical, or to some other type, if that type is equivalent
+ * and was chosen as canonical representative. This mapping is stored in
+ * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
+ * FWD type got resolved to.
+ *
+ * To facilitate fast discovery of canonical types, we also maintain canonical
+ * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
+ * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
+ * that match that signature. With sufficiently good choice of type signature
+ * hashing function, we can limit number of canonical types for each unique type
+ * signature to a very small number, allowing to find canonical type for any
+ * duplicated type very quickly.
+ *
+ * Struct/union deduplication is the most critical part and algorithm for
+ * deduplicating structs/unions is described in greater details in comments for
+ * `btf_dedup_is_equiv` function.
+ */
+int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
+ const struct btf_dedup_opts *opts)
+{
+ struct btf_dedup *d = btf_dedup_new(btf, btf_ext, opts);
+ int err;
+
+ if (IS_ERR(d)) {
+ pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
+ return -EINVAL;
+ }
+
+ err = btf_dedup_strings(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_strings failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_prim_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_prim_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_struct_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_struct_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_ref_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_ref_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_compact_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_compact_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_remap_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_remap_types failed:%d\n", err);
+ goto done;
+ }
+
+done:
+ btf_dedup_free(d);
+ return err;
+}
+
+#define BTF_UNPROCESSED_ID ((__u32)-1)
+#define BTF_IN_PROGRESS_ID ((__u32)-2)
+
+struct btf_dedup {
+ /* .BTF section to be deduped in-place */
+ struct btf *btf;
+ /*
+ * Optional .BTF.ext section. When provided, any strings referenced
+ * from it will be taken into account when deduping strings
+ */
+ struct btf_ext *btf_ext;
+ /*
+ * This is a map from any type's signature hash to a list of possible
+ * canonical representative type candidates. Hash collisions are
+ * ignored, so even types of various kinds can share same list of
+ * candidates, which is fine because we rely on subsequent
+ * btf_xxx_equal() checks to authoritatively verify type equality.
+ */
+ struct hashmap *dedup_table;
+ /* Canonical types map */
+ __u32 *map;
+ /* Hypothetical mapping, used during type graph equivalence checks */
+ __u32 *hypot_map;
+ __u32 *hypot_list;
+ size_t hypot_cnt;
+ size_t hypot_cap;
+ /* Various option modifying behavior of algorithm */
+ struct btf_dedup_opts opts;
+};
+
+struct btf_str_ptr {
+ const char *str;
+ __u32 new_off;
+ bool used;
+};
+
+struct btf_str_ptrs {
+ struct btf_str_ptr *ptrs;
+ const char *data;
+ __u32 cnt;
+ __u32 cap;
+};
+
+static long hash_combine(long h, long value)
+{
+ return h * 31 + value;
+}
+
+#define for_each_dedup_cand(d, node, hash) \
+ hashmap__for_each_key_entry(d->dedup_table, node, (void *)hash)
+
+static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
+{
+ return hashmap__append(d->dedup_table,
+ (void *)hash, (void *)(long)type_id);
+}
+
+static int btf_dedup_hypot_map_add(struct btf_dedup *d,
+ __u32 from_id, __u32 to_id)
+{
+ if (d->hypot_cnt == d->hypot_cap) {
+ __u32 *new_list;
+
+ d->hypot_cap += max(16, d->hypot_cap / 2);
+ new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
+ if (!new_list)
+ return -ENOMEM;
+ d->hypot_list = new_list;
+ }
+ d->hypot_list[d->hypot_cnt++] = from_id;
+ d->hypot_map[from_id] = to_id;
+ return 0;
+}
+
+static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
+{
+ int i;
+
+ for (i = 0; i < d->hypot_cnt; i++)
+ d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
+ d->hypot_cnt = 0;
+}
+
+static void btf_dedup_free(struct btf_dedup *d)
+{
+ hashmap__free(d->dedup_table);
+ d->dedup_table = NULL;
+
+ free(d->map);
+ d->map = NULL;
+
+ free(d->hypot_map);
+ d->hypot_map = NULL;
+
+ free(d->hypot_list);
+ d->hypot_list = NULL;
+
+ free(d);
+}
+
+static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx)
+{
+ return (size_t)key;
+}
+
+static size_t btf_dedup_collision_hash_fn(const void *key, void *ctx)
+{
+ return 0;
+}
+
+static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx)
+{
+ return k1 == k2;
+}
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
+ const struct btf_dedup_opts *opts)
+{
+ struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
+ hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
+ int i, err = 0;
+
+ if (!d)
+ return ERR_PTR(-ENOMEM);
+
+ d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
+ /* dedup_table_size is now used only to force collisions in tests */
+ if (opts && opts->dedup_table_size == 1)
+ hash_fn = btf_dedup_collision_hash_fn;
+
+ d->btf = btf;
+ d->btf_ext = btf_ext;
+
+ d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
+ if (IS_ERR(d->dedup_table)) {
+ err = PTR_ERR(d->dedup_table);
+ d->dedup_table = NULL;
+ goto done;
+ }
+
+ d->map = malloc(sizeof(__u32) * (1 + btf->nr_types));
+ if (!d->map) {
+ err = -ENOMEM;
+ goto done;
+ }
+ /* special BTF "void" type is made canonical immediately */
+ d->map[0] = 0;
+ for (i = 1; i <= btf->nr_types; i++) {
+ struct btf_type *t = d->btf->types[i];
+
+ /* VAR and DATASEC are never deduped and are self-canonical */
+ if (btf_is_var(t) || btf_is_datasec(t))
+ d->map[i] = i;
+ else
+ d->map[i] = BTF_UNPROCESSED_ID;
+ }
+
+ d->hypot_map = malloc(sizeof(__u32) * (1 + btf->nr_types));
+ if (!d->hypot_map) {
+ err = -ENOMEM;
+ goto done;
+ }
+ for (i = 0; i <= btf->nr_types; i++)
+ d->hypot_map[i] = BTF_UNPROCESSED_ID;
+
+done:
+ if (err) {
+ btf_dedup_free(d);
+ return ERR_PTR(err);
+ }
+
+ return d;
+}
+
+typedef int (*str_off_fn_t)(__u32 *str_off_ptr, void *ctx);
+
+/*
+ * Iterate over all possible places in .BTF and .BTF.ext that can reference
+ * string and pass pointer to it to a provided callback `fn`.
+ */
+static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
+{
+ void *line_data_cur, *line_data_end;
+ int i, j, r, rec_size;
+ struct btf_type *t;
+
+ for (i = 1; i <= d->btf->nr_types; i++) {
+ t = d->btf->types[i];
+ r = fn(&t->name_off, ctx);
+ if (r)
+ return r;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ struct btf_member *m = btf_members(t);
+ __u16 vlen = btf_vlen(t);
+
+ for (j = 0; j < vlen; j++) {
+ r = fn(&m->name_off, ctx);
+ if (r)
+ return r;
+ m++;
+ }
+ break;
+ }
+ case BTF_KIND_ENUM: {
+ struct btf_enum *m = btf_enum(t);
+ __u16 vlen = btf_vlen(t);
+
+ for (j = 0; j < vlen; j++) {
+ r = fn(&m->name_off, ctx);
+ if (r)
+ return r;
+ m++;
+ }
+ break;
+ }
+ case BTF_KIND_FUNC_PROTO: {
+ struct btf_param *m = btf_params(t);
+ __u16 vlen = btf_vlen(t);
+
+ for (j = 0; j < vlen; j++) {
+ r = fn(&m->name_off, ctx);
+ if (r)
+ return r;
+ m++;
+ }
+ break;
+ }
+ default:
+ break;
+ }
+ }
+
+ if (!d->btf_ext)
+ return 0;
+
+ line_data_cur = d->btf_ext->line_info.info;
+ line_data_end = d->btf_ext->line_info.info + d->btf_ext->line_info.len;
+ rec_size = d->btf_ext->line_info.rec_size;
+
+ while (line_data_cur < line_data_end) {
+ struct btf_ext_info_sec *sec = line_data_cur;
+ struct bpf_line_info_min *line_info;
+ __u32 num_info = sec->num_info;
+
+ r = fn(&sec->sec_name_off, ctx);
+ if (r)
+ return r;
+
+ line_data_cur += sizeof(struct btf_ext_info_sec);
+ for (i = 0; i < num_info; i++) {
+ line_info = line_data_cur;
+ r = fn(&line_info->file_name_off, ctx);
+ if (r)
+ return r;
+ r = fn(&line_info->line_off, ctx);
+ if (r)
+ return r;
+ line_data_cur += rec_size;
+ }
+ }
+
+ return 0;
+}
+
+static int str_sort_by_content(const void *a1, const void *a2)
+{
+ const struct btf_str_ptr *p1 = a1;
+ const struct btf_str_ptr *p2 = a2;
+
+ return strcmp(p1->str, p2->str);
+}
+
+static int str_sort_by_offset(const void *a1, const void *a2)
+{
+ const struct btf_str_ptr *p1 = a1;
+ const struct btf_str_ptr *p2 = a2;
+
+ if (p1->str != p2->str)
+ return p1->str < p2->str ? -1 : 1;
+ return 0;
+}
+
+static int btf_dedup_str_ptr_cmp(const void *str_ptr, const void *pelem)
+{
+ const struct btf_str_ptr *p = pelem;
+
+ if (str_ptr != p->str)
+ return (const char *)str_ptr < p->str ? -1 : 1;
+ return 0;
+}
+
+static int btf_str_mark_as_used(__u32 *str_off_ptr, void *ctx)
+{
+ struct btf_str_ptrs *strs;
+ struct btf_str_ptr *s;
+
+ if (*str_off_ptr == 0)
+ return 0;
+
+ strs = ctx;
+ s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
+ sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
+ if (!s)
+ return -EINVAL;
+ s->used = true;
+ return 0;
+}
+
+static int btf_str_remap_offset(__u32 *str_off_ptr, void *ctx)
+{
+ struct btf_str_ptrs *strs;
+ struct btf_str_ptr *s;
+
+ if (*str_off_ptr == 0)
+ return 0;
+
+ strs = ctx;
+ s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
+ sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
+ if (!s)
+ return -EINVAL;
+ *str_off_ptr = s->new_off;
+ return 0;
+}
+
+/*
+ * Dedup string and filter out those that are not referenced from either .BTF
+ * or .BTF.ext (if provided) sections.
+ *
+ * This is done by building index of all strings in BTF's string section,
+ * then iterating over all entities that can reference strings (e.g., type
+ * names, struct field names, .BTF.ext line info, etc) and marking corresponding
+ * strings as used. After that all used strings are deduped and compacted into
+ * sequential blob of memory and new offsets are calculated. Then all the string
+ * references are iterated again and rewritten using new offsets.
+ */
+static int btf_dedup_strings(struct btf_dedup *d)
+{
+ const struct btf_header *hdr = d->btf->hdr;
+ char *start = (char *)d->btf->nohdr_data + hdr->str_off;
+ char *end = start + d->btf->hdr->str_len;
+ char *p = start, *tmp_strs = NULL;
+ struct btf_str_ptrs strs = {
+ .cnt = 0,
+ .cap = 0,
+ .ptrs = NULL,
+ .data = start,
+ };
+ int i, j, err = 0, grp_idx;
+ bool grp_used;
+
+ /* build index of all strings */
+ while (p < end) {
+ if (strs.cnt + 1 > strs.cap) {
+ struct btf_str_ptr *new_ptrs;
+
+ strs.cap += max(strs.cnt / 2, 16);
+ new_ptrs = realloc(strs.ptrs,
+ sizeof(strs.ptrs[0]) * strs.cap);
+ if (!new_ptrs) {
+ err = -ENOMEM;
+ goto done;
+ }
+ strs.ptrs = new_ptrs;
+ }
+
+ strs.ptrs[strs.cnt].str = p;
+ strs.ptrs[strs.cnt].used = false;
+
+ p += strlen(p) + 1;
+ strs.cnt++;
+ }
+
+ /* temporary storage for deduplicated strings */
+ tmp_strs = malloc(d->btf->hdr->str_len);
+ if (!tmp_strs) {
+ err = -ENOMEM;
+ goto done;
+ }
+
+ /* mark all used strings */
+ strs.ptrs[0].used = true;
+ err = btf_for_each_str_off(d, btf_str_mark_as_used, &strs);
+ if (err)
+ goto done;
+
+ /* sort strings by context, so that we can identify duplicates */
+ qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_content);
+
+ /*
+ * iterate groups of equal strings and if any instance in a group was
+ * referenced, emit single instance and remember new offset
+ */
+ p = tmp_strs;
+ grp_idx = 0;
+ grp_used = strs.ptrs[0].used;
+ /* iterate past end to avoid code duplication after loop */
+ for (i = 1; i <= strs.cnt; i++) {
+ /*
+ * when i == strs.cnt, we want to skip string comparison and go
+ * straight to handling last group of strings (otherwise we'd
+ * need to handle last group after the loop w/ duplicated code)
+ */
+ if (i < strs.cnt &&
+ !strcmp(strs.ptrs[i].str, strs.ptrs[grp_idx].str)) {
+ grp_used = grp_used || strs.ptrs[i].used;
+ continue;
+ }
+
+ /*
+ * this check would have been required after the loop to handle
+ * last group of strings, but due to <= condition in a loop
+ * we avoid that duplication
+ */
+ if (grp_used) {
+ int new_off = p - tmp_strs;
+ __u32 len = strlen(strs.ptrs[grp_idx].str);
+
+ memmove(p, strs.ptrs[grp_idx].str, len + 1);
+ for (j = grp_idx; j < i; j++)
+ strs.ptrs[j].new_off = new_off;
+ p += len + 1;
+ }
+
+ if (i < strs.cnt) {
+ grp_idx = i;
+ grp_used = strs.ptrs[i].used;
+ }
+ }
+
+ /* replace original strings with deduped ones */
+ d->btf->hdr->str_len = p - tmp_strs;
+ memmove(start, tmp_strs, d->btf->hdr->str_len);
+ end = start + d->btf->hdr->str_len;
+
+ /* restore original order for further binary search lookups */
+ qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_offset);
+
+ /* remap string offsets */
+ err = btf_for_each_str_off(d, btf_str_remap_offset, &strs);
+ if (err)
+ goto done;
+
+ d->btf->hdr->str_len = end - start;
+
+done:
+ free(tmp_strs);
+ free(strs.ptrs);
+ return err;
+}
+
+static long btf_hash_common(struct btf_type *t)
+{
+ long h;
+
+ h = hash_combine(0, t->name_off);
+ h = hash_combine(h, t->info);
+ h = hash_combine(h, t->size);
+ return h;
+}
+
+static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
+{
+ return t1->name_off == t2->name_off &&
+ t1->info == t2->info &&
+ t1->size == t2->size;
+}
+
+/* Calculate type signature hash of INT. */
+static long btf_hash_int(struct btf_type *t)
+{
+ __u32 info = *(__u32 *)(t + 1);
+ long h;
+
+ h = btf_hash_common(t);
+ h = hash_combine(h, info);
+ return h;
+}
+
+/* Check structural equality of two INTs. */
+static bool btf_equal_int(struct btf_type *t1, struct btf_type *t2)
+{
+ __u32 info1, info2;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+ info1 = *(__u32 *)(t1 + 1);
+ info2 = *(__u32 *)(t2 + 1);
+ return info1 == info2;
+}
+
+/* Calculate type signature hash of ENUM. */
+static long btf_hash_enum(struct btf_type *t)
+{
+ long h;
+
+ /* don't hash vlen and enum members to support enum fwd resolving */
+ h = hash_combine(0, t->name_off);
+ h = hash_combine(h, t->info & ~0xffff);
+ h = hash_combine(h, t->size);
+ return h;
+}
+
+/* Check structural equality of two ENUMs. */
+static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_enum *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_enum(t1);
+ m2 = btf_enum(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->val != m2->val)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+static inline bool btf_is_enum_fwd(struct btf_type *t)
+{
+ return btf_is_enum(t) && btf_vlen(t) == 0;
+}
+
+static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
+{
+ if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
+ return btf_equal_enum(t1, t2);
+ /* ignore vlen when comparing */
+ return t1->name_off == t2->name_off &&
+ (t1->info & ~0xffff) == (t2->info & ~0xffff) &&
+ t1->size == t2->size;
+}
+
+/*
+ * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
+ * as referenced type IDs equivalence is established separately during type
+ * graph equivalence check algorithm.
+ */
+static long btf_hash_struct(struct btf_type *t)
+{
+ const struct btf_member *member = btf_members(t);
+ __u32 vlen = btf_vlen(t);
+ long h = btf_hash_common(t);
+ int i;
+
+ for (i = 0; i < vlen; i++) {
+ h = hash_combine(h, member->name_off);
+ h = hash_combine(h, member->offset);
+ /* no hashing of referenced type ID, it can be unresolved yet */
+ member++;
+ }
+ return h;
+}
+
+/*
+ * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_member *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_members(t1);
+ m2 = btf_members(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->offset != m2->offset)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/*
+ * Calculate type signature hash of ARRAY, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_array(struct btf_type *t)
+{
+ const struct btf_array *info = btf_array(t);
+ long h = btf_hash_common(t);
+
+ h = hash_combine(h, info->type);
+ h = hash_combine(h, info->index_type);
+ h = hash_combine(h, info->nelems);
+ return h;
+}
+
+/*
+ * Check exact equality of two ARRAYs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * ARRAY to potential canonical representative.
+ */
+static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_array *info1, *info2;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ info1 = btf_array(t1);
+ info2 = btf_array(t2);
+ return info1->type == info2->type &&
+ info1->index_type == info2->index_type &&
+ info1->nelems == info2->nelems;
+}
+
+/*
+ * Check structural compatibility of two ARRAYs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
+{
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ return btf_array(t1)->nelems == btf_array(t2)->nelems;
+}
+
+/*
+ * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_fnproto(struct btf_type *t)
+{
+ const struct btf_param *member = btf_params(t);
+ __u16 vlen = btf_vlen(t);
+ long h = btf_hash_common(t);
+ int i;
+
+ for (i = 0; i < vlen; i++) {
+ h = hash_combine(h, member->name_off);
+ h = hash_combine(h, member->type);
+ member++;
+ }
+ return h;
+}
+
+/*
+ * Check exact equality of two FUNC_PROTOs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * FUNC_PROTO to potential canonical representative.
+ */
+static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_param *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_params(t1);
+ m2 = btf_params(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->type != m2->type)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/*
+ * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_param *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ /* skip return type ID */
+ if (t1->name_off != t2->name_off || t1->info != t2->info)
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_params(t1);
+ m2 = btf_params(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/*
+ * Deduplicate primitive types, that can't reference other types, by calculating
+ * their type signature hash and comparing them with any possible canonical
+ * candidate. If no canonical candidate matches, type itself is marked as
+ * canonical and is added into `btf_dedup->dedup_table` as another candidate.
+ */
+static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct btf_type *t = d->btf->types[type_id];
+ struct hashmap_entry *hash_entry;
+ struct btf_type *cand;
+ /* if we don't find equivalent type, then we are canonical */
+ __u32 new_id = type_id;
+ __u32 cand_id;
+ long h;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_ARRAY:
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_FUNC_PROTO:
+ case BTF_KIND_VAR:
+ case BTF_KIND_DATASEC:
+ return 0;
+
+ case BTF_KIND_INT:
+ h = btf_hash_int(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = (__u32)(long)hash_entry->value;
+ cand = d->btf->types[cand_id];
+ if (btf_equal_int(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ case BTF_KIND_ENUM:
+ h = btf_hash_enum(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = (__u32)(long)hash_entry->value;
+ cand = d->btf->types[cand_id];
+ if (btf_equal_enum(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ if (d->opts.dont_resolve_fwds)
+ continue;
+ if (btf_compat_enum(t, cand)) {
+ if (btf_is_enum_fwd(t)) {
+ /* resolve fwd to full enum */
+ new_id = cand_id;
+ break;
+ }
+ /* resolve canonical enum fwd to full enum */
+ d->map[cand_id] = type_id;
+ }
+ }
+ break;
+
+ case BTF_KIND_FWD:
+ h = btf_hash_common(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = (__u32)(long)hash_entry->value;
+ cand = d->btf->types[cand_id];
+ if (btf_equal_common(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ d->map[type_id] = new_id;
+ if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int btf_dedup_prim_types(struct btf_dedup *d)
+{
+ int i, err;
+
+ for (i = 1; i <= d->btf->nr_types; i++) {
+ err = btf_dedup_prim_type(d, i);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+/*
+ * Check whether type is already mapped into canonical one (could be to itself).
+ */
+static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
+{
+ return d->map[type_id] <= BTF_MAX_NR_TYPES;
+}
+
+/*
+ * Resolve type ID into its canonical type ID, if any; otherwise return original
+ * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
+ * STRUCT/UNION link and resolve it into canonical type ID as well.
+ */
+static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
+{
+ while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+ type_id = d->map[type_id];
+ return type_id;
+}
+
+/*
+ * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
+ * type ID.
+ */
+static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
+{
+ __u32 orig_type_id = type_id;
+
+ if (!btf_is_fwd(d->btf->types[type_id]))
+ return type_id;
+
+ while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+ type_id = d->map[type_id];
+
+ if (!btf_is_fwd(d->btf->types[type_id]))
+ return type_id;
+
+ return orig_type_id;
+}
+
+
+static inline __u16 btf_fwd_kind(struct btf_type *t)
+{
+ return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
+}
+
+/*
+ * Check equivalence of BTF type graph formed by candidate struct/union (we'll
+ * call it "candidate graph" in this description for brevity) to a type graph
+ * formed by (potential) canonical struct/union ("canonical graph" for brevity
+ * here, though keep in mind that not all types in canonical graph are
+ * necessarily canonical representatives themselves, some of them might be
+ * duplicates or its uniqueness might not have been established yet).
+ * Returns:
+ * - >0, if type graphs are equivalent;
+ * - 0, if not equivalent;
+ * - <0, on error.
+ *
+ * Algorithm performs side-by-side DFS traversal of both type graphs and checks
+ * equivalence of BTF types at each step. If at any point BTF types in candidate
+ * and canonical graphs are not compatible structurally, whole graphs are
+ * incompatible. If types are structurally equivalent (i.e., all information
+ * except referenced type IDs is exactly the same), a mapping from `canon_id` to
+ * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
+ * If a type references other types, then those referenced types are checked
+ * for equivalence recursively.
+ *
+ * During DFS traversal, if we find that for current `canon_id` type we
+ * already have some mapping in hypothetical map, we check for two possible
+ * situations:
+ * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
+ * happen when type graphs have cycles. In this case we assume those two
+ * types are equivalent.
+ * - `canon_id` is mapped to different type. This is contradiction in our
+ * hypothetical mapping, because same graph in canonical graph corresponds
+ * to two different types in candidate graph, which for equivalent type
+ * graphs shouldn't happen. This condition terminates equivalence check
+ * with negative result.
+ *
+ * If type graphs traversal exhausts types to check and find no contradiction,
+ * then type graphs are equivalent.
+ *
+ * When checking types for equivalence, there is one special case: FWD types.
+ * If FWD type resolution is allowed and one of the types (either from canonical
+ * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
+ * flag) and their names match, hypothetical mapping is updated to point from
+ * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
+ * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
+ *
+ * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
+ * if there are two exactly named (or anonymous) structs/unions that are
+ * compatible structurally, one of which has FWD field, while other is concrete
+ * STRUCT/UNION, but according to C sources they are different structs/unions
+ * that are referencing different types with the same name. This is extremely
+ * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
+ * this logic is causing problems.
+ *
+ * Doing FWD resolution means that both candidate and/or canonical graphs can
+ * consists of portions of the graph that come from multiple compilation units.
+ * This is due to the fact that types within single compilation unit are always
+ * deduplicated and FWDs are already resolved, if referenced struct/union
+ * definiton is available. So, if we had unresolved FWD and found corresponding
+ * STRUCT/UNION, they will be from different compilation units. This
+ * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
+ * type graph will likely have at least two different BTF types that describe
+ * same type (e.g., most probably there will be two different BTF types for the
+ * same 'int' primitive type) and could even have "overlapping" parts of type
+ * graph that describe same subset of types.
+ *
+ * This in turn means that our assumption that each type in canonical graph
+ * must correspond to exactly one type in candidate graph might not hold
+ * anymore and will make it harder to detect contradictions using hypothetical
+ * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
+ * resolution only in canonical graph. FWDs in candidate graphs are never
+ * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
+ * that can occur:
+ * - Both types in canonical and candidate graphs are FWDs. If they are
+ * structurally equivalent, then they can either be both resolved to the
+ * same STRUCT/UNION or not resolved at all. In both cases they are
+ * equivalent and there is no need to resolve FWD on candidate side.
+ * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
+ * so nothing to resolve as well, algorithm will check equivalence anyway.
+ * - Type in canonical graph is FWD, while type in candidate is concrete
+ * STRUCT/UNION. In this case candidate graph comes from single compilation
+ * unit, so there is exactly one BTF type for each unique C type. After
+ * resolving FWD into STRUCT/UNION, there might be more than one BTF type
+ * in canonical graph mapping to single BTF type in candidate graph, but
+ * because hypothetical mapping maps from canonical to candidate types, it's
+ * alright, and we still maintain the property of having single `canon_id`
+ * mapping to single `cand_id` (there could be two different `canon_id`
+ * mapped to the same `cand_id`, but it's not contradictory).
+ * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
+ * graph is FWD. In this case we are just going to check compatibility of
+ * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
+ * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
+ * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
+ * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
+ * canonical graph.
+ */
+static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
+ __u32 canon_id)
+{
+ struct btf_type *cand_type;
+ struct btf_type *canon_type;
+ __u32 hypot_type_id;
+ __u16 cand_kind;
+ __u16 canon_kind;
+ int i, eq;
+
+ /* if both resolve to the same canonical, they must be equivalent */
+ if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
+ return 1;
+
+ canon_id = resolve_fwd_id(d, canon_id);
+
+ hypot_type_id = d->hypot_map[canon_id];
+ if (hypot_type_id <= BTF_MAX_NR_TYPES)
+ return hypot_type_id == cand_id;
+
+ if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
+ return -ENOMEM;
+
+ cand_type = d->btf->types[cand_id];
+ canon_type = d->btf->types[canon_id];
+ cand_kind = btf_kind(cand_type);
+ canon_kind = btf_kind(canon_type);
+
+ if (cand_type->name_off != canon_type->name_off)
+ return 0;
+
+ /* FWD <--> STRUCT/UNION equivalence check, if enabled */
+ if (!d->opts.dont_resolve_fwds
+ && (cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
+ && cand_kind != canon_kind) {
+ __u16 real_kind;
+ __u16 fwd_kind;
+
+ if (cand_kind == BTF_KIND_FWD) {
+ real_kind = canon_kind;
+ fwd_kind = btf_fwd_kind(cand_type);
+ } else {
+ real_kind = cand_kind;
+ fwd_kind = btf_fwd_kind(canon_type);
+ }
+ return fwd_kind == real_kind;
+ }
+
+ if (cand_kind != canon_kind)
+ return 0;
+
+ switch (cand_kind) {
+ case BTF_KIND_INT:
+ return btf_equal_int(cand_type, canon_type);
+
+ case BTF_KIND_ENUM:
+ if (d->opts.dont_resolve_fwds)
+ return btf_equal_enum(cand_type, canon_type);
+ else
+ return btf_compat_enum(cand_type, canon_type);
+
+ case BTF_KIND_FWD:
+ return btf_equal_common(cand_type, canon_type);
+
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ if (cand_type->info != canon_type->info)
+ return 0;
+ return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+
+ case BTF_KIND_ARRAY: {
+ const struct btf_array *cand_arr, *canon_arr;
+
+ if (!btf_compat_array(cand_type, canon_type))
+ return 0;
+ cand_arr = btf_array(cand_type);
+ canon_arr = btf_array(canon_type);
+ eq = btf_dedup_is_equiv(d,
+ cand_arr->index_type, canon_arr->index_type);
+ if (eq <= 0)
+ return eq;
+ return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
+ }
+
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ const struct btf_member *cand_m, *canon_m;
+ __u16 vlen;
+
+ if (!btf_shallow_equal_struct(cand_type, canon_type))
+ return 0;
+ vlen = btf_vlen(cand_type);
+ cand_m = btf_members(cand_type);
+ canon_m = btf_members(canon_type);
+ for (i = 0; i < vlen; i++) {
+ eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
+ if (eq <= 0)
+ return eq;
+ cand_m++;
+ canon_m++;
+ }
+
+ return 1;
+ }
+
+ case BTF_KIND_FUNC_PROTO: {
+ const struct btf_param *cand_p, *canon_p;
+ __u16 vlen;
+
+ if (!btf_compat_fnproto(cand_type, canon_type))
+ return 0;
+ eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+ if (eq <= 0)
+ return eq;
+ vlen = btf_vlen(cand_type);
+ cand_p = btf_params(cand_type);
+ canon_p = btf_params(canon_type);
+ for (i = 0; i < vlen; i++) {
+ eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
+ if (eq <= 0)
+ return eq;
+ cand_p++;
+ canon_p++;
+ }
+ return 1;
+ }
+
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/*
+ * Use hypothetical mapping, produced by successful type graph equivalence
+ * check, to augment existing struct/union canonical mapping, where possible.
+ *
+ * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
+ * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
+ * it doesn't matter if FWD type was part of canonical graph or candidate one,
+ * we are recording the mapping anyway. As opposed to carefulness required
+ * for struct/union correspondence mapping (described below), for FWD resolution
+ * it's not important, as by the time that FWD type (reference type) will be
+ * deduplicated all structs/unions will be deduped already anyway.
+ *
+ * Recording STRUCT/UNION mapping is purely a performance optimization and is
+ * not required for correctness. It needs to be done carefully to ensure that
+ * struct/union from candidate's type graph is not mapped into corresponding
+ * struct/union from canonical type graph that itself hasn't been resolved into
+ * canonical representative. The only guarantee we have is that canonical
+ * struct/union was determined as canonical and that won't change. But any
+ * types referenced through that struct/union fields could have been not yet
+ * resolved, so in case like that it's too early to establish any kind of
+ * correspondence between structs/unions.
+ *
+ * No canonical correspondence is derived for primitive types (they are already
+ * deduplicated completely already anyway) or reference types (they rely on
+ * stability of struct/union canonical relationship for equivalence checks).
+ */
+static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
+{
+ __u32 cand_type_id, targ_type_id;
+ __u16 t_kind, c_kind;
+ __u32 t_id, c_id;
+ int i;
+
+ for (i = 0; i < d->hypot_cnt; i++) {
+ cand_type_id = d->hypot_list[i];
+ targ_type_id = d->hypot_map[cand_type_id];
+ t_id = resolve_type_id(d, targ_type_id);
+ c_id = resolve_type_id(d, cand_type_id);
+ t_kind = btf_kind(d->btf->types[t_id]);
+ c_kind = btf_kind(d->btf->types[c_id]);
+ /*
+ * Resolve FWD into STRUCT/UNION.
+ * It's ok to resolve FWD into STRUCT/UNION that's not yet
+ * mapped to canonical representative (as opposed to
+ * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
+ * eventually that struct is going to be mapped and all resolved
+ * FWDs will automatically resolve to correct canonical
+ * representative. This will happen before ref type deduping,
+ * which critically depends on stability of these mapping. This
+ * stability is not a requirement for STRUCT/UNION equivalence
+ * checks, though.
+ */
+ if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
+ d->map[c_id] = t_id;
+ else if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
+ d->map[t_id] = c_id;
+
+ if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
+ c_kind != BTF_KIND_FWD &&
+ is_type_mapped(d, c_id) &&
+ !is_type_mapped(d, t_id)) {
+ /*
+ * as a perf optimization, we can map struct/union
+ * that's part of type graph we just verified for
+ * equivalence. We can do that for struct/union that has
+ * canonical representative only, though.
+ */
+ d->map[t_id] = c_id;
+ }
+ }
+}
+
+/*
+ * Deduplicate struct/union types.
+ *
+ * For each struct/union type its type signature hash is calculated, taking
+ * into account type's name, size, number, order and names of fields, but
+ * ignoring type ID's referenced from fields, because they might not be deduped
+ * completely until after reference types deduplication phase. This type hash
+ * is used to iterate over all potential canonical types, sharing same hash.
+ * For each canonical candidate we check whether type graphs that they form
+ * (through referenced types in fields and so on) are equivalent using algorithm
+ * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
+ * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
+ * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
+ * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
+ * potentially map other structs/unions to their canonical representatives,
+ * if such relationship hasn't yet been established. This speeds up algorithm
+ * by eliminating some of the duplicate work.
+ *
+ * If no matching canonical representative was found, struct/union is marked
+ * as canonical for itself and is added into btf_dedup->dedup_table hash map
+ * for further look ups.
+ */
+static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct btf_type *cand_type, *t;
+ struct hashmap_entry *hash_entry;
+ /* if we don't find equivalent type, then we are canonical */
+ __u32 new_id = type_id;
+ __u16 kind;
+ long h;
+
+ /* already deduped or is in process of deduping (loop detected) */
+ if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+ return 0;
+
+ t = d->btf->types[type_id];
+ kind = btf_kind(t);
+
+ if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
+ return 0;
+
+ h = btf_hash_struct(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ __u32 cand_id = (__u32)(long)hash_entry->value;
+ int eq;
+
+ /*
+ * Even though btf_dedup_is_equiv() checks for
+ * btf_shallow_equal_struct() internally when checking two
+ * structs (unions) for equivalence, we need to guard here
+ * from picking matching FWD type as a dedup candidate.
+ * This can happen due to hash collision. In such case just
+ * relying on btf_dedup_is_equiv() would lead to potentially
+ * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
+ * FWD and compatible STRUCT/UNION are considered equivalent.
+ */
+ cand_type = d->btf->types[cand_id];
+ if (!btf_shallow_equal_struct(t, cand_type))
+ continue;
+
+ btf_dedup_clear_hypot_map(d);
+ eq = btf_dedup_is_equiv(d, type_id, cand_id);
+ if (eq < 0)
+ return eq;
+ if (!eq)
+ continue;
+ new_id = cand_id;
+ btf_dedup_merge_hypot_map(d);
+ break;
+ }
+
+ d->map[type_id] = new_id;
+ if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int btf_dedup_struct_types(struct btf_dedup *d)
+{
+ int i, err;
+
+ for (i = 1; i <= d->btf->nr_types; i++) {
+ err = btf_dedup_struct_type(d, i);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+/*
+ * Deduplicate reference type.
+ *
+ * Once all primitive and struct/union types got deduplicated, we can easily
+ * deduplicate all other (reference) BTF types. This is done in two steps:
+ *
+ * 1. Resolve all referenced type IDs into their canonical type IDs. This
+ * resolution can be done either immediately for primitive or struct/union types
+ * (because they were deduped in previous two phases) or recursively for
+ * reference types. Recursion will always terminate at either primitive or
+ * struct/union type, at which point we can "unwind" chain of reference types
+ * one by one. There is no danger of encountering cycles because in C type
+ * system the only way to form type cycle is through struct/union, so any chain
+ * of reference types, even those taking part in a type cycle, will inevitably
+ * reach struct/union at some point.
+ *
+ * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
+ * becomes "stable", in the sense that no further deduplication will cause
+ * any changes to it. With that, it's now possible to calculate type's signature
+ * hash (this time taking into account referenced type IDs) and loop over all
+ * potential canonical representatives. If no match was found, current type
+ * will become canonical representative of itself and will be added into
+ * btf_dedup->dedup_table as another possible canonical representative.
+ */
+static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct hashmap_entry *hash_entry;
+ __u32 new_id = type_id, cand_id;
+ struct btf_type *t, *cand;
+ /* if we don't find equivalent type, then we are representative type */
+ int ref_type_id;
+ long h;
+
+ if (d->map[type_id] == BTF_IN_PROGRESS_ID)
+ return -ELOOP;
+ if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+ return resolve_type_id(d, type_id);
+
+ t = d->btf->types[type_id];
+ d->map[type_id] = BTF_IN_PROGRESS_ID;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ ref_type_id = btf_dedup_ref_type(d, t->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ t->type = ref_type_id;
+
+ h = btf_hash_common(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = (__u32)(long)hash_entry->value;
+ cand = d->btf->types[cand_id];
+ if (btf_equal_common(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ case BTF_KIND_ARRAY: {
+ struct btf_array *info = btf_array(t);
+
+ ref_type_id = btf_dedup_ref_type(d, info->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ info->type = ref_type_id;
+
+ ref_type_id = btf_dedup_ref_type(d, info->index_type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ info->index_type = ref_type_id;
+
+ h = btf_hash_array(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = (__u32)(long)hash_entry->value;
+ cand = d->btf->types[cand_id];
+ if (btf_equal_array(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+ }
+
+ case BTF_KIND_FUNC_PROTO: {
+ struct btf_param *param;
+ __u16 vlen;
+ int i;
+
+ ref_type_id = btf_dedup_ref_type(d, t->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ t->type = ref_type_id;
+
+ vlen = btf_vlen(t);
+ param = btf_params(t);
+ for (i = 0; i < vlen; i++) {
+ ref_type_id = btf_dedup_ref_type(d, param->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ param->type = ref_type_id;
+ param++;
+ }
+
+ h = btf_hash_fnproto(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = (__u32)(long)hash_entry->value;
+ cand = d->btf->types[cand_id];
+ if (btf_equal_fnproto(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+ }
+
+ default:
+ return -EINVAL;
+ }
+
+ d->map[type_id] = new_id;
+ if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+
+ return new_id;
+}
+
+static int btf_dedup_ref_types(struct btf_dedup *d)
+{
+ int i, err;
+
+ for (i = 1; i <= d->btf->nr_types; i++) {
+ err = btf_dedup_ref_type(d, i);
+ if (err < 0)
+ return err;
+ }
+ /* we won't need d->dedup_table anymore */
+ hashmap__free(d->dedup_table);
+ d->dedup_table = NULL;
+ return 0;
+}
+
+/*
+ * Compact types.
+ *
+ * After we established for each type its corresponding canonical representative
+ * type, we now can eliminate types that are not canonical and leave only
+ * canonical ones layed out sequentially in memory by copying them over
+ * duplicates. During compaction btf_dedup->hypot_map array is reused to store
+ * a map from original type ID to a new compacted type ID, which will be used
+ * during next phase to "fix up" type IDs, referenced from struct/union and
+ * reference types.
+ */
+static int btf_dedup_compact_types(struct btf_dedup *d)
+{
+ struct btf_type **new_types;
+ __u32 next_type_id = 1;
+ char *types_start, *p;
+ int i, len;
+
+ /* we are going to reuse hypot_map to store compaction remapping */
+ d->hypot_map[0] = 0;
+ for (i = 1; i <= d->btf->nr_types; i++)
+ d->hypot_map[i] = BTF_UNPROCESSED_ID;
+
+ types_start = d->btf->nohdr_data + d->btf->hdr->type_off;
+ p = types_start;
+
+ for (i = 1; i <= d->btf->nr_types; i++) {
+ if (d->map[i] != i)
+ continue;
+
+ len = btf_type_size(d->btf->types[i]);
+ if (len < 0)
+ return len;
+
+ memmove(p, d->btf->types[i], len);
+ d->hypot_map[i] = next_type_id;
+ d->btf->types[next_type_id] = (struct btf_type *)p;
+ p += len;
+ next_type_id++;
+ }
+
+ /* shrink struct btf's internal types index and update btf_header */
+ d->btf->nr_types = next_type_id - 1;
+ d->btf->types_size = d->btf->nr_types;
+ d->btf->hdr->type_len = p - types_start;
+ new_types = realloc(d->btf->types,
+ (1 + d->btf->nr_types) * sizeof(struct btf_type *));
+ if (!new_types)
+ return -ENOMEM;
+ d->btf->types = new_types;
+
+ /* make sure string section follows type information without gaps */
+ d->btf->hdr->str_off = p - (char *)d->btf->nohdr_data;
+ memmove(p, d->btf->strings, d->btf->hdr->str_len);
+ d->btf->strings = p;
+ p += d->btf->hdr->str_len;
+
+ d->btf->data_size = p - (char *)d->btf->data;
+ return 0;
+}
+
+/*
+ * Figure out final (deduplicated and compacted) type ID for provided original
+ * `type_id` by first resolving it into corresponding canonical type ID and
+ * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
+ * which is populated during compaction phase.
+ */
+static int btf_dedup_remap_type_id(struct btf_dedup *d, __u32 type_id)
+{
+ __u32 resolved_type_id, new_type_id;
+
+ resolved_type_id = resolve_type_id(d, type_id);
+ new_type_id = d->hypot_map[resolved_type_id];
+ if (new_type_id > BTF_MAX_NR_TYPES)
+ return -EINVAL;
+ return new_type_id;
+}
+
+/*
+ * Remap referenced type IDs into deduped type IDs.
+ *
+ * After BTF types are deduplicated and compacted, their final type IDs may
+ * differ from original ones. The map from original to a corresponding
+ * deduped type ID is stored in btf_dedup->hypot_map and is populated during
+ * compaction phase. During remapping phase we are rewriting all type IDs
+ * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
+ * their final deduped type IDs.
+ */
+static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct btf_type *t = d->btf->types[type_id];
+ int i, r;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_INT:
+ case BTF_KIND_ENUM:
+ break;
+
+ case BTF_KIND_FWD:
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_VAR:
+ r = btf_dedup_remap_type_id(d, t->type);
+ if (r < 0)
+ return r;
+ t->type = r;
+ break;
+
+ case BTF_KIND_ARRAY: {
+ struct btf_array *arr_info = btf_array(t);
+
+ r = btf_dedup_remap_type_id(d, arr_info->type);
+ if (r < 0)
+ return r;
+ arr_info->type = r;
+ r = btf_dedup_remap_type_id(d, arr_info->index_type);
+ if (r < 0)
+ return r;
+ arr_info->index_type = r;
+ break;
+ }
+
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ struct btf_member *member = btf_members(t);
+ __u16 vlen = btf_vlen(t);
+
+ for (i = 0; i < vlen; i++) {
+ r = btf_dedup_remap_type_id(d, member->type);
+ if (r < 0)
+ return r;
+ member->type = r;
+ member++;
+ }
+ break;
+ }
+
+ case BTF_KIND_FUNC_PROTO: {
+ struct btf_param *param = btf_params(t);
+ __u16 vlen = btf_vlen(t);
+
+ r = btf_dedup_remap_type_id(d, t->type);
+ if (r < 0)
+ return r;
+ t->type = r;
+
+ for (i = 0; i < vlen; i++) {
+ r = btf_dedup_remap_type_id(d, param->type);
+ if (r < 0)
+ return r;
+ param->type = r;
+ param++;
+ }
+ break;
+ }
+
+ case BTF_KIND_DATASEC: {
+ struct btf_var_secinfo *var = btf_var_secinfos(t);
+ __u16 vlen = btf_vlen(t);
+
+ for (i = 0; i < vlen; i++) {
+ r = btf_dedup_remap_type_id(d, var->type);
+ if (r < 0)
+ return r;
+ var->type = r;
+ var++;
+ }
+ break;
+ }
+
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int btf_dedup_remap_types(struct btf_dedup *d)
+{
+ int i, r;
+
+ for (i = 1; i <= d->btf->nr_types; i++) {
+ r = btf_dedup_remap_type(d, i);
+ if (r < 0)
+ return r;
+ }
+ return 0;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-09 20:44:53 +0000