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-rw-r--r--tools/bpf/resolve_btfids/main.c783
1 files changed, 783 insertions, 0 deletions
diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
new file mode 100644
index 000000000..770581740
--- /dev/null
+++ b/tools/bpf/resolve_btfids/main.c
@@ -0,0 +1,783 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * resolve_btfids scans Elf object for .BTF_ids section and resolves
+ * its symbols with BTF ID values.
+ *
+ * Each symbol points to 4 bytes data and is expected to have
+ * following name syntax:
+ *
+ * __BTF_ID__<type>__<symbol>[__<id>]
+ *
+ * type is:
+ *
+ * func - lookup BTF_KIND_FUNC symbol with <symbol> name
+ * and store its ID into the data:
+ *
+ * __BTF_ID__func__vfs_close__1:
+ * .zero 4
+ *
+ * struct - lookup BTF_KIND_STRUCT symbol with <symbol> name
+ * and store its ID into the data:
+ *
+ * __BTF_ID__struct__sk_buff__1:
+ * .zero 4
+ *
+ * union - lookup BTF_KIND_UNION symbol with <symbol> name
+ * and store its ID into the data:
+ *
+ * __BTF_ID__union__thread_union__1:
+ * .zero 4
+ *
+ * typedef - lookup BTF_KIND_TYPEDEF symbol with <symbol> name
+ * and store its ID into the data:
+ *
+ * __BTF_ID__typedef__pid_t__1:
+ * .zero 4
+ *
+ * set - store symbol size into first 4 bytes and sort following
+ * ID list
+ *
+ * __BTF_ID__set__list:
+ * .zero 4
+ * list:
+ * __BTF_ID__func__vfs_getattr__3:
+ * .zero 4
+ * __BTF_ID__func__vfs_fallocate__4:
+ * .zero 4
+ *
+ * set8 - store symbol size into first 4 bytes and sort following
+ * ID list
+ *
+ * __BTF_ID__set8__list:
+ * .zero 8
+ * list:
+ * __BTF_ID__func__vfs_getattr__3:
+ * .zero 4
+ * .word (1 << 0) | (1 << 2)
+ * __BTF_ID__func__vfs_fallocate__5:
+ * .zero 4
+ * .word (1 << 3) | (1 << 1) | (1 << 2)
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <linux/rbtree.h>
+#include <linux/zalloc.h>
+#include <linux/err.h>
+#include <bpf/btf.h>
+#include <bpf/libbpf.h>
+#include <subcmd/parse-options.h>
+
+#define BTF_IDS_SECTION ".BTF_ids"
+#define BTF_ID "__BTF_ID__"
+
+#define BTF_STRUCT "struct"
+#define BTF_UNION "union"
+#define BTF_TYPEDEF "typedef"
+#define BTF_FUNC "func"
+#define BTF_SET "set"
+#define BTF_SET8 "set8"
+
+#define ADDR_CNT 100
+
+struct btf_id {
+ struct rb_node rb_node;
+ char *name;
+ union {
+ int id;
+ int cnt;
+ };
+ int addr_cnt;
+ bool is_set;
+ bool is_set8;
+ Elf64_Addr addr[ADDR_CNT];
+};
+
+struct object {
+ const char *path;
+ const char *btf;
+ const char *base_btf_path;
+
+ struct {
+ int fd;
+ Elf *elf;
+ Elf_Data *symbols;
+ Elf_Data *idlist;
+ int symbols_shndx;
+ int idlist_shndx;
+ size_t strtabidx;
+ unsigned long idlist_addr;
+ } efile;
+
+ struct rb_root sets;
+ struct rb_root structs;
+ struct rb_root unions;
+ struct rb_root typedefs;
+ struct rb_root funcs;
+
+ int nr_funcs;
+ int nr_structs;
+ int nr_unions;
+ int nr_typedefs;
+};
+
+static int verbose;
+
+static int eprintf(int level, int var, const char *fmt, ...)
+{
+ va_list args;
+ int ret = 0;
+
+ if (var >= level) {
+ va_start(args, fmt);
+ ret = vfprintf(stderr, fmt, args);
+ va_end(args);
+ }
+ return ret;
+}
+
+#ifndef pr_fmt
+#define pr_fmt(fmt) fmt
+#endif
+
+#define pr_debug(fmt, ...) \
+ eprintf(1, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debugN(n, fmt, ...) \
+ eprintf(n, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debug2(fmt, ...) pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_err(fmt, ...) \
+ eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_info(fmt, ...) \
+ eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+
+static bool is_btf_id(const char *name)
+{
+ return name && !strncmp(name, BTF_ID, sizeof(BTF_ID) - 1);
+}
+
+static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
+{
+ struct rb_node *p = root->rb_node;
+ struct btf_id *id;
+ int cmp;
+
+ while (p) {
+ id = rb_entry(p, struct btf_id, rb_node);
+ cmp = strcmp(id->name, name);
+ if (cmp < 0)
+ p = p->rb_left;
+ else if (cmp > 0)
+ p = p->rb_right;
+ else
+ return id;
+ }
+ return NULL;
+}
+
+static struct btf_id *
+btf_id__add(struct rb_root *root, char *name, bool unique)
+{
+ struct rb_node **p = &root->rb_node;
+ struct rb_node *parent = NULL;
+ struct btf_id *id;
+ int cmp;
+
+ while (*p != NULL) {
+ parent = *p;
+ id = rb_entry(parent, struct btf_id, rb_node);
+ cmp = strcmp(id->name, name);
+ if (cmp < 0)
+ p = &(*p)->rb_left;
+ else if (cmp > 0)
+ p = &(*p)->rb_right;
+ else
+ return unique ? NULL : id;
+ }
+
+ id = zalloc(sizeof(*id));
+ if (id) {
+ pr_debug("adding symbol %s\n", name);
+ id->name = name;
+ rb_link_node(&id->rb_node, parent, p);
+ rb_insert_color(&id->rb_node, root);
+ }
+ return id;
+}
+
+static char *get_id(const char *prefix_end)
+{
+ /*
+ * __BTF_ID__func__vfs_truncate__0
+ * prefix_end = ^
+ * pos = ^
+ */
+ int len = strlen(prefix_end);
+ int pos = sizeof("__") - 1;
+ char *p, *id;
+
+ if (pos >= len)
+ return NULL;
+
+ id = strdup(prefix_end + pos);
+ if (id) {
+ /*
+ * __BTF_ID__func__vfs_truncate__0
+ * id = ^
+ *
+ * cut the unique id part
+ */
+ p = strrchr(id, '_');
+ p--;
+ if (*p != '_') {
+ free(id);
+ return NULL;
+ }
+ *p = '\0';
+ }
+ return id;
+}
+
+static struct btf_id *add_set(struct object *obj, char *name, bool is_set8)
+{
+ /*
+ * __BTF_ID__set__name
+ * name = ^
+ * id = ^
+ */
+ char *id = name + (is_set8 ? sizeof(BTF_SET8 "__") : sizeof(BTF_SET "__")) - 1;
+ int len = strlen(name);
+
+ if (id >= name + len) {
+ pr_err("FAILED to parse set name: %s\n", name);
+ return NULL;
+ }
+
+ return btf_id__add(&obj->sets, id, true);
+}
+
+static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
+{
+ char *id;
+
+ id = get_id(name + size);
+ if (!id) {
+ pr_err("FAILED to parse symbol name: %s\n", name);
+ return NULL;
+ }
+
+ return btf_id__add(root, id, false);
+}
+
+/* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */
+#ifndef SHF_COMPRESSED
+#define SHF_COMPRESSED (1 << 11) /* Section with compressed data. */
+#endif
+
+/*
+ * The data of compressed section should be aligned to 4
+ * (for 32bit) or 8 (for 64 bit) bytes. The binutils ld
+ * sets sh_addralign to 1, which makes libelf fail with
+ * misaligned section error during the update:
+ * FAILED elf_update(WRITE): invalid section alignment
+ *
+ * While waiting for ld fix, we fix the compressed sections
+ * sh_addralign value manualy.
+ */
+static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh)
+{
+ int expected = gelf_getclass(elf) == ELFCLASS32 ? 4 : 8;
+
+ if (!(sh->sh_flags & SHF_COMPRESSED))
+ return 0;
+
+ if (sh->sh_addralign == expected)
+ return 0;
+
+ pr_debug2(" - fixing wrong alignment sh_addralign %u, expected %u\n",
+ sh->sh_addralign, expected);
+
+ sh->sh_addralign = expected;
+
+ if (gelf_update_shdr(scn, sh) == 0) {
+ pr_err("FAILED cannot update section header: %s\n",
+ elf_errmsg(-1));
+ return -1;
+ }
+ return 0;
+}
+
+static int elf_collect(struct object *obj)
+{
+ Elf_Scn *scn = NULL;
+ size_t shdrstrndx;
+ int idx = 0;
+ Elf *elf;
+ int fd;
+
+ fd = open(obj->path, O_RDWR, 0666);
+ if (fd == -1) {
+ pr_err("FAILED cannot open %s: %s\n",
+ obj->path, strerror(errno));
+ return -1;
+ }
+
+ elf_version(EV_CURRENT);
+
+ elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL);
+ if (!elf) {
+ close(fd);
+ pr_err("FAILED cannot create ELF descriptor: %s\n",
+ elf_errmsg(-1));
+ return -1;
+ }
+
+ obj->efile.fd = fd;
+ obj->efile.elf = elf;
+
+ elf_flagelf(elf, ELF_C_SET, ELF_F_LAYOUT);
+
+ if (elf_getshdrstrndx(elf, &shdrstrndx) != 0) {
+ pr_err("FAILED cannot get shdr str ndx\n");
+ return -1;
+ }
+
+ /*
+ * Scan all the elf sections and look for save data
+ * from .BTF_ids section and symbols.
+ */
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
+ Elf_Data *data;
+ GElf_Shdr sh;
+ char *name;
+
+ idx++;
+ if (gelf_getshdr(scn, &sh) != &sh) {
+ pr_err("FAILED get section(%d) header\n", idx);
+ return -1;
+ }
+
+ name = elf_strptr(elf, shdrstrndx, sh.sh_name);
+ if (!name) {
+ pr_err("FAILED get section(%d) name\n", idx);
+ return -1;
+ }
+
+ data = elf_getdata(scn, 0);
+ if (!data) {
+ pr_err("FAILED to get section(%d) data from %s\n",
+ idx, name);
+ return -1;
+ }
+
+ pr_debug2("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
+ idx, name, (unsigned long) data->d_size,
+ (int) sh.sh_link, (unsigned long) sh.sh_flags,
+ (int) sh.sh_type);
+
+ if (sh.sh_type == SHT_SYMTAB) {
+ obj->efile.symbols = data;
+ obj->efile.symbols_shndx = idx;
+ obj->efile.strtabidx = sh.sh_link;
+ } else if (!strcmp(name, BTF_IDS_SECTION)) {
+ obj->efile.idlist = data;
+ obj->efile.idlist_shndx = idx;
+ obj->efile.idlist_addr = sh.sh_addr;
+ }
+
+ if (compressed_section_fix(elf, scn, &sh))
+ return -1;
+ }
+
+ return 0;
+}
+
+static int symbols_collect(struct object *obj)
+{
+ Elf_Scn *scn = NULL;
+ int n, i;
+ GElf_Shdr sh;
+ char *name;
+
+ scn = elf_getscn(obj->efile.elf, obj->efile.symbols_shndx);
+ if (!scn)
+ return -1;
+
+ if (gelf_getshdr(scn, &sh) != &sh)
+ return -1;
+
+ n = sh.sh_size / sh.sh_entsize;
+
+ /*
+ * Scan symbols and look for the ones starting with
+ * __BTF_ID__* over .BTF_ids section.
+ */
+ for (i = 0; i < n; i++) {
+ char *prefix;
+ struct btf_id *id;
+ GElf_Sym sym;
+
+ if (!gelf_getsym(obj->efile.symbols, i, &sym))
+ return -1;
+
+ if (sym.st_shndx != obj->efile.idlist_shndx)
+ continue;
+
+ name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+ sym.st_name);
+
+ if (!is_btf_id(name))
+ continue;
+
+ /*
+ * __BTF_ID__TYPE__vfs_truncate__0
+ * prefix = ^
+ */
+ prefix = name + sizeof(BTF_ID) - 1;
+
+ /* struct */
+ if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
+ obj->nr_structs++;
+ id = add_symbol(&obj->structs, prefix, sizeof(BTF_STRUCT) - 1);
+ /* union */
+ } else if (!strncmp(prefix, BTF_UNION, sizeof(BTF_UNION) - 1)) {
+ obj->nr_unions++;
+ id = add_symbol(&obj->unions, prefix, sizeof(BTF_UNION) - 1);
+ /* typedef */
+ } else if (!strncmp(prefix, BTF_TYPEDEF, sizeof(BTF_TYPEDEF) - 1)) {
+ obj->nr_typedefs++;
+ id = add_symbol(&obj->typedefs, prefix, sizeof(BTF_TYPEDEF) - 1);
+ /* func */
+ } else if (!strncmp(prefix, BTF_FUNC, sizeof(BTF_FUNC) - 1)) {
+ obj->nr_funcs++;
+ id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
+ /* set8 */
+ } else if (!strncmp(prefix, BTF_SET8, sizeof(BTF_SET8) - 1)) {
+ id = add_set(obj, prefix, true);
+ /*
+ * SET8 objects store list's count, which is encoded
+ * in symbol's size, together with 'cnt' field hence
+ * that - 1.
+ */
+ if (id) {
+ id->cnt = sym.st_size / sizeof(uint64_t) - 1;
+ id->is_set8 = true;
+ }
+ /* set */
+ } else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
+ id = add_set(obj, prefix, false);
+ /*
+ * SET objects store list's count, which is encoded
+ * in symbol's size, together with 'cnt' field hence
+ * that - 1.
+ */
+ if (id) {
+ id->cnt = sym.st_size / sizeof(int) - 1;
+ id->is_set = true;
+ }
+ } else {
+ pr_err("FAILED unsupported prefix %s\n", prefix);
+ return -1;
+ }
+
+ if (!id)
+ return -ENOMEM;
+
+ if (id->addr_cnt >= ADDR_CNT) {
+ pr_err("FAILED symbol %s crossed the number of allowed lists\n",
+ id->name);
+ return -1;
+ }
+ id->addr[id->addr_cnt++] = sym.st_value;
+ }
+
+ return 0;
+}
+
+static int symbols_resolve(struct object *obj)
+{
+ int nr_typedefs = obj->nr_typedefs;
+ int nr_structs = obj->nr_structs;
+ int nr_unions = obj->nr_unions;
+ int nr_funcs = obj->nr_funcs;
+ struct btf *base_btf = NULL;
+ int err, type_id;
+ struct btf *btf;
+ __u32 nr_types;
+
+ if (obj->base_btf_path) {
+ base_btf = btf__parse(obj->base_btf_path, NULL);
+ err = libbpf_get_error(base_btf);
+ if (err) {
+ pr_err("FAILED: load base BTF from %s: %s\n",
+ obj->base_btf_path, strerror(-err));
+ return -1;
+ }
+ }
+
+ btf = btf__parse_split(obj->btf ?: obj->path, base_btf);
+ err = libbpf_get_error(btf);
+ if (err) {
+ pr_err("FAILED: load BTF from %s: %s\n",
+ obj->btf ?: obj->path, strerror(-err));
+ goto out;
+ }
+
+ err = -1;
+ nr_types = btf__type_cnt(btf);
+
+ /*
+ * Iterate all the BTF types and search for collected symbol IDs.
+ */
+ for (type_id = 1; type_id < nr_types; type_id++) {
+ const struct btf_type *type;
+ struct rb_root *root;
+ struct btf_id *id;
+ const char *str;
+ int *nr;
+
+ type = btf__type_by_id(btf, type_id);
+ if (!type) {
+ pr_err("FAILED: malformed BTF, can't resolve type for ID %d\n",
+ type_id);
+ goto out;
+ }
+
+ if (btf_is_func(type) && nr_funcs) {
+ nr = &nr_funcs;
+ root = &obj->funcs;
+ } else if (btf_is_struct(type) && nr_structs) {
+ nr = &nr_structs;
+ root = &obj->structs;
+ } else if (btf_is_union(type) && nr_unions) {
+ nr = &nr_unions;
+ root = &obj->unions;
+ } else if (btf_is_typedef(type) && nr_typedefs) {
+ nr = &nr_typedefs;
+ root = &obj->typedefs;
+ } else
+ continue;
+
+ str = btf__name_by_offset(btf, type->name_off);
+ if (!str) {
+ pr_err("FAILED: malformed BTF, can't resolve name for ID %d\n",
+ type_id);
+ goto out;
+ }
+
+ id = btf_id__find(root, str);
+ if (id) {
+ if (id->id) {
+ pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",
+ str, id->id, type_id, id->id);
+ } else {
+ id->id = type_id;
+ (*nr)--;
+ }
+ }
+ }
+
+ err = 0;
+out:
+ btf__free(base_btf);
+ btf__free(btf);
+ return err;
+}
+
+static int id_patch(struct object *obj, struct btf_id *id)
+{
+ Elf_Data *data = obj->efile.idlist;
+ int *ptr = data->d_buf;
+ int i;
+
+ /* For set, set8, id->id may be 0 */
+ if (!id->id && !id->is_set && !id->is_set8)
+ pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
+
+ for (i = 0; i < id->addr_cnt; i++) {
+ unsigned long addr = id->addr[i];
+ unsigned long idx = addr - obj->efile.idlist_addr;
+
+ pr_debug("patching addr %5lu: ID %7d [%s]\n",
+ idx, id->id, id->name);
+
+ if (idx >= data->d_size) {
+ pr_err("FAILED patching index %lu out of bounds %lu\n",
+ idx, data->d_size);
+ return -1;
+ }
+
+ idx = idx / sizeof(int);
+ ptr[idx] = id->id;
+ }
+
+ return 0;
+}
+
+static int __symbols_patch(struct object *obj, struct rb_root *root)
+{
+ struct rb_node *next;
+ struct btf_id *id;
+
+ next = rb_first(root);
+ while (next) {
+ id = rb_entry(next, struct btf_id, rb_node);
+
+ if (id_patch(obj, id))
+ return -1;
+
+ next = rb_next(next);
+ }
+ return 0;
+}
+
+static int cmp_id(const void *pa, const void *pb)
+{
+ const int *a = pa, *b = pb;
+
+ return *a - *b;
+}
+
+static int sets_patch(struct object *obj)
+{
+ Elf_Data *data = obj->efile.idlist;
+ int *ptr = data->d_buf;
+ struct rb_node *next;
+
+ next = rb_first(&obj->sets);
+ while (next) {
+ unsigned long addr, idx;
+ struct btf_id *id;
+ int *base;
+ int cnt;
+
+ id = rb_entry(next, struct btf_id, rb_node);
+ addr = id->addr[0];
+ idx = addr - obj->efile.idlist_addr;
+
+ /* sets are unique */
+ if (id->addr_cnt != 1) {
+ pr_err("FAILED malformed data for set '%s'\n",
+ id->name);
+ return -1;
+ }
+
+ idx = idx / sizeof(int);
+ base = &ptr[idx] + (id->is_set8 ? 2 : 1);
+ cnt = ptr[idx];
+
+ pr_debug("sorting addr %5lu: cnt %6d [%s]\n",
+ (idx + 1) * sizeof(int), cnt, id->name);
+
+ qsort(base, cnt, id->is_set8 ? sizeof(uint64_t) : sizeof(int), cmp_id);
+
+ next = rb_next(next);
+ }
+ return 0;
+}
+
+static int symbols_patch(struct object *obj)
+{
+ int err;
+
+ if (__symbols_patch(obj, &obj->structs) ||
+ __symbols_patch(obj, &obj->unions) ||
+ __symbols_patch(obj, &obj->typedefs) ||
+ __symbols_patch(obj, &obj->funcs) ||
+ __symbols_patch(obj, &obj->sets))
+ return -1;
+
+ if (sets_patch(obj))
+ return -1;
+
+ /* Set type to ensure endian translation occurs. */
+ obj->efile.idlist->d_type = ELF_T_WORD;
+
+ elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
+
+ err = elf_update(obj->efile.elf, ELF_C_WRITE);
+ if (err < 0) {
+ pr_err("FAILED elf_update(WRITE): %s\n",
+ elf_errmsg(-1));
+ }
+
+ pr_debug("update %s for %s\n",
+ err >= 0 ? "ok" : "failed", obj->path);
+ return err < 0 ? -1 : 0;
+}
+
+static const char * const resolve_btfids_usage[] = {
+ "resolve_btfids [<options>] <ELF object>",
+ NULL
+};
+
+int main(int argc, const char **argv)
+{
+ struct object obj = {
+ .efile = {
+ .idlist_shndx = -1,
+ .symbols_shndx = -1,
+ },
+ .structs = RB_ROOT,
+ .unions = RB_ROOT,
+ .typedefs = RB_ROOT,
+ .funcs = RB_ROOT,
+ .sets = RB_ROOT,
+ };
+ struct option btfid_options[] = {
+ OPT_INCR('v', "verbose", &verbose,
+ "be more verbose (show errors, etc)"),
+ OPT_STRING(0, "btf", &obj.btf, "BTF data",
+ "BTF data"),
+ OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
+ "path of file providing base BTF"),
+ OPT_END()
+ };
+ int err = -1;
+
+ argc = parse_options(argc, argv, btfid_options, resolve_btfids_usage,
+ PARSE_OPT_STOP_AT_NON_OPTION);
+ if (argc != 1)
+ usage_with_options(resolve_btfids_usage, btfid_options);
+
+ obj.path = argv[0];
+
+ if (elf_collect(&obj))
+ goto out;
+
+ /*
+ * We did not find .BTF_ids section or symbols section,
+ * nothing to do..
+ */
+ if (obj.efile.idlist_shndx == -1 ||
+ obj.efile.symbols_shndx == -1) {
+ pr_debug("Cannot find .BTF_ids or symbols sections, nothing to do\n");
+ err = 0;
+ goto out;
+ }
+
+ if (symbols_collect(&obj))
+ goto out;
+
+ if (symbols_resolve(&obj))
+ goto out;
+
+ if (symbols_patch(&obj))
+ goto out;
+
+ err = 0;
+out:
+ if (obj.efile.elf) {
+ elf_end(obj.efile.elf);
+ close(obj.efile.fd);
+ }
+ return err;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-03 08:51:07 +0000