| // 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 <sys/utsname.h> |
| #include <sys/param.h> |
| #include <sys/stat.h> |
| #include <linux/kernel.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" |
| |
| /* make sure libbpf doesn't use kernel-only integer typedefs */ |
| #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64 |
| |
| #define BTF_MAX_NR_TYPES 0x7fffffffU |
| #define BTF_MAX_STR_OFFSET 0x7fffffffU |
| |
| 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, 16U); |
| 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__align_of(const struct btf *btf, __u32 id) |
| { |
| const struct btf_type *t = btf__type_by_id(btf, id); |
| __u16 kind = btf_kind(t); |
| |
| switch (kind) { |
| case BTF_KIND_INT: |
| case BTF_KIND_ENUM: |
| return min(sizeof(void *), (size_t)t->size); |
| case BTF_KIND_PTR: |
| return sizeof(void *); |
| case BTF_KIND_TYPEDEF: |
| case BTF_KIND_VOLATILE: |
| case BTF_KIND_CONST: |
| case BTF_KIND_RESTRICT: |
| return btf__align_of(btf, t->type); |
| case BTF_KIND_ARRAY: |
| return btf__align_of(btf, btf_array(t)->type); |
| case BTF_KIND_STRUCT: |
| case BTF_KIND_UNION: { |
| const struct btf_member *m = btf_members(t); |
| __u16 vlen = btf_vlen(t); |
| int i, max_align = 1, align; |
| |
| for (i = 0; i < vlen; i++, m++) { |
| align = btf__align_of(btf, m->type); |
| if (align <= 0) |
| return align; |
| max_align = max(max_align, align); |
| } |
| |
| return max_align; |
| } |
| default: |
| pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t)); |
| return 0; |
| } |
| } |
| |
| 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 (IS_ERR_OR_NULL(btf)) |
| return; |
| |
| if (btf->fd >= 0) |
| close(btf->fd); |
| |
| free(btf->data); |
| free(btf->types); |
| free(btf); |
| } |
| |
| struct btf *btf__new(const void *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; |
| } |
| |
| struct btf *btf__parse_raw(const char *path) |
| { |
| struct btf *btf = NULL; |
| void *data = NULL; |
| FILE *f = NULL; |
| __u16 magic; |
| int err = 0; |
| long sz; |
| |
| f = fopen(path, "rb"); |
| if (!f) { |
| err = -errno; |
| goto err_out; |
| } |
| |
| /* check BTF magic */ |
| if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) { |
| err = -EIO; |
| goto err_out; |
| } |
| if (magic != BTF_MAGIC) { |
| /* definitely not a raw BTF */ |
| err = -EPROTO; |
| goto err_out; |
| } |
| |
| /* get file size */ |
| if (fseek(f, 0, SEEK_END)) { |
| err = -errno; |
| goto err_out; |
| } |
| sz = ftell(f); |
| if (sz < 0) { |
| err = -errno; |
| goto err_out; |
| } |
| /* rewind to the start */ |
| if (fseek(f, 0, SEEK_SET)) { |
| err = -errno; |
| goto err_out; |
| } |
| |
| /* pre-alloc memory and read all of BTF data */ |
| data = malloc(sz); |
| if (!data) { |
| err = -ENOMEM; |
| goto err_out; |
| } |
| if (fread(data, 1, sz, f) < sz) { |
| err = -EIO; |
| goto err_out; |
| } |
| |
| /* finally parse BTF data */ |
| btf = btf__new(data, sz); |
| |
| err_out: |
| free(data); |
| if (f) |
| fclose(f); |
| return err ? ERR_PTR(err) : btf; |
| } |
| |
| struct btf *btf__parse(const char *path, struct btf_ext **btf_ext) |
| { |
| struct btf *btf; |
| |
| if (btf_ext) |
| *btf_ext = NULL; |
| |
| btf = btf__parse_raw(path); |
| if (!IS_ERR(btf) || PTR_ERR(btf) != -EPROTO) |
| return btf; |
| |
| return btf__parse_elf(path, btf_ext); |
| } |
| |
| 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; |
| } |
| |
| /* .extern datasec size and var offsets were set correctly during |
| * extern collection step, so just skip straight to sorting variables |
| */ |
| if (t->size) |
| goto sort_vars; |
| |
| 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; |
| } |
| |
| sort_vars: |
| qsort(btf_var_secinfos(t), 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 = 0; |
| char *log_buf = NULL; |
| int err = 0; |
| |
| if (btf->fd >= 0) |
| return -EEXIST; |
| |
| retry_load: |
| if (log_buf_size) { |
| 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) { |
| if (!log_buf || errno == ENOSPC) { |
| log_buf_size = max((__u32)BPF_LOG_BUF_SIZE, |
| log_buf_size << 1); |
| free(log_buf); |
| goto retry_load; |
| } |
| |
| 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; |
| } |
| |
| void btf__set_fd(struct btf *btf, int fd) |
| { |
| btf->fd = 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, ¶m); |
| } |
| |
| 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, ¶m); |
| } |
| |
| 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, ¶m); |
| } |
| |
| 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 (IS_ERR_OR_NULL(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((size_t)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, 16U); |
| 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; |
| } |
| |
| /* |
| * Probe few well-known locations for vmlinux kernel image and try to load BTF |
| * data out of it to use for target BTF. |
| */ |
| struct btf *libbpf_find_kernel_btf(void) |
| { |
| struct { |
| const char *path_fmt; |
| bool raw_btf; |
| } locations[] = { |
| /* try canonical vmlinux BTF through sysfs first */ |
| { "/sys/kernel/btf/vmlinux", true /* raw BTF */ }, |
| /* fall back to trying to find vmlinux ELF on disk otherwise */ |
| { "/boot/vmlinux-%1$s" }, |
| { "/lib/modules/%1$s/vmlinux-%1$s" }, |
| { "/lib/modules/%1$s/build/vmlinux" }, |
| { "/usr/lib/modules/%1$s/kernel/vmlinux" }, |
| { "/usr/lib/debug/boot/vmlinux-%1$s" }, |
| { "/usr/lib/debug/boot/vmlinux-%1$s.debug" }, |
| { "/usr/lib/debug/lib/modules/%1$s/vmlinux" }, |
| }; |
| char path[PATH_MAX + 1]; |
| struct utsname buf; |
| struct btf *btf; |
| int i; |
| |
| uname(&buf); |
| |
| for (i = 0; i < ARRAY_SIZE(locations); i++) { |
| snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release); |
| |
| if (access(path, R_OK)) |
| continue; |
| |
| if (locations[i].raw_btf) |
| btf = btf__parse_raw(path); |
| else |
| btf = btf__parse_elf(path, NULL); |
| |
| pr_debug("loading kernel BTF '%s': %ld\n", |
| path, IS_ERR(btf) ? PTR_ERR(btf) : 0); |
| if (IS_ERR(btf)) |
| continue; |
| |
| return btf; |
| } |
| |
| pr_warn("failed to find valid kernel BTF\n"); |
| return ERR_PTR(-ESRCH); |
| } |