// SPDX-License-Identifier: GPL-2.0-or-later/* * elf.c - ELF access library * * Adapted from kpatch (https://github.com/dynup/kpatch): * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com> * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> */ #include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <errno.h>#include "builtin.h" #include "elf.h"#include "warn.h" #define MAX_NAME_LEN 128 static inline u32 str_hash(const char *str){ return jhash(str, strlen(str), 0);} static inline int elf_hash_bits(void){ return vmlinux ? ELF_HASH_BITS : 16;} #define elf_hash_add(hashtable, node, key) \ hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())]) static void elf_hash_init(struct hlist_head *table){ __hash_init(table, 1U << elf_hash_bits());} #define elf_hash_for_each_possible(name, obj, member, key) \ hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member) static void rb_add(struct rb_root *tree, struct rb_node *node, int (*cmp)(struct rb_node *, const struct rb_node *)){ struct rb_node **link = &tree->rb_node; struct rb_node *parent = NULL; while (*link) { parent = *link; if (cmp(node, parent) < 0) link = &parent->rb_left; else link = &parent->rb_right; } rb_link_node(node, parent, link); rb_insert_color(node, tree);} static struct rb_node *rb_find_first(const struct rb_root *tree, const void *key, int (*cmp)(const void *key, const struct rb_node *)){ struct rb_node *node = tree->rb_node; struct rb_node *match = NULL; while (node) { int c = cmp(key, node); if (c <= 0) { if (!c) match = node; node = node->rb_left; } else if (c > 0) { node = node->rb_right; } } return match;} static struct rb_node *rb_next_match(struct rb_node *node, const void *key, int (*cmp)(const void *key, const struct rb_node *)){ node = rb_next(node); if (node && cmp(key, node)) node = NULL; return node;} #define rb_for_each(tree, node, key, cmp) \ for ((node) = rb_find_first((tree), (key), (cmp)); \ (node); (node) = rb_next_match((node), (key), (cmp))) static int symbol_to_offset(struct rb_node *a, const struct rb_node *b){ struct symbol *sa = rb_entry(a, struct symbol, node); struct symbol *sb = rb_entry(b, struct symbol, node); if (sa->offset < sb->offset) return -1; if (sa->offset > sb->offset) return 1; if (sa->len < sb->len) return -1; if (sa->len > sb->len) return 1; sa->alias = sb; return 0;} static int symbol_by_offset(const void *key, const struct rb_node *node){ const struct symbol *s = rb_entry(node, struct symbol, node); const unsigned long *o = key; if (*o < s->offset) return -1; if (*o >= s->offset + s->len) return 1; return 0;} struct section *find_section_by_name(const struct elf *elf, const char *name){ struct section *sec; elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name)) if (!strcmp(sec->name, name)) return sec; return NULL;} static struct section *find_section_by_index(struct elf *elf, unsigned int idx){ struct section *sec; elf_hash_for_each_possible(elf->section_hash, sec, hash, idx) if (sec->idx == idx) return sec; return NULL;} static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx){ struct symbol *sym; elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx) if (sym->idx == idx) return sym; return NULL;} struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset){ struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->offset == offset && s->type != STT_SECTION) return s; } return NULL;} struct symbol *find_func_by_offset(struct section *sec, unsigned long offset){ struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->offset == offset && s->type == STT_FUNC) return s; } return NULL;} struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset){ struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->type != STT_SECTION) return s; } return NULL;} struct symbol *find_func_containing(struct section *sec, unsigned long offset){ struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->type == STT_FUNC) return s; } return NULL;} struct symbol *find_symbol_by_name(const struct elf *elf, const char *name){ struct symbol *sym; elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name)) if (!strcmp(sym->name, name)) return sym; return NULL;} struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec, unsigned long offset, unsigned int len){ struct reloc *reloc, *r = NULL; unsigned long o; if (!sec->reloc) return NULL; sec = sec->reloc; for_offset_range(o, offset, offset + len) { elf_hash_for_each_possible(elf->reloc_hash, reloc, hash, sec_offset_hash(sec, o)) { if (reloc->sec != sec) continue; if (reloc->offset >= offset && reloc->offset < offset + len) { if (!r || reloc->offset < r->offset) r = reloc; } } if (r) return r; } return NULL;} struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset){ return find_reloc_by_dest_range(elf, sec, offset, 1);} static int read_sections(struct elf *elf){ Elf_Scn *s = NULL; struct section *sec; size_t shstrndx, sections_nr; int i; if (elf_getshdrnum(elf->elf, §ions_nr)) { WARN_ELF("elf_getshdrnum"); return -1; } if (elf_getshdrstrndx(elf->elf, &shstrndx)) { WARN_ELF("elf_getshdrstrndx"); return -1; } for (i = 0; i < sections_nr; i++) { sec = malloc(sizeof(*sec)); if (!sec) { perror("malloc"); return -1; } memset(sec, 0, sizeof(*sec)); INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->reloc_list); s = elf_getscn(elf->elf, i); if (!s) { WARN_ELF("elf_getscn"); return -1; } sec->idx = elf_ndxscn(s); if (!gelf_getshdr(s, &sec->sh)) { WARN_ELF("gelf_getshdr"); return -1; } sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); if (!sec->name) { WARN_ELF("elf_strptr"); return -1; } if (sec->sh.sh_size != 0) { sec->data = elf_getdata(s, NULL); if (!sec->data) { WARN_ELF("elf_getdata"); return -1; } if (sec->data->d_off != 0 || sec->data->d_size != sec->sh.sh_size) { WARN("unexpected data attributes for %s", sec->name); return -1; } } sec->len = sec->sh.sh_size; list_add_tail(&sec->list, &elf->sections); elf_hash_add(elf->section_hash, &sec->hash, sec->idx); elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name)); } if (stats) printf("nr_sections: %lu\n", (unsigned long)sections_nr); /* sanity check, one more call to elf_nextscn() should return NULL */ if (elf_nextscn(elf->elf, s)) { WARN("section entry mismatch"); return -1; } return 0;} static int read_symbols(struct elf *elf){ struct section *symtab, *symtab_shndx, *sec; struct symbol *sym, *pfunc; struct list_head *entry; struct rb_node *pnode; int symbols_nr, i; char *coldstr; Elf_Data *shndx_data = NULL; Elf32_Word shndx; symtab = find_section_by_name(elf, ".symtab"); if (!symtab) { WARN("missing symbol table"); return -1; } symtab_shndx = find_section_by_name(elf, ".symtab_shndx"); if (symtab_shndx) shndx_data = symtab_shndx->data; symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; for (i = 0; i < symbols_nr; i++) { sym = malloc(sizeof(*sym)); if (!sym) { perror("malloc"); return -1; } memset(sym, 0, sizeof(*sym)); sym->alias = sym; sym->idx = i; if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym, &shndx)) { WARN_ELF("gelf_getsymshndx"); goto err; } sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, sym->sym.st_name); if (!sym->name) { WARN_ELF("elf_strptr"); goto err; } sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); if ((sym->sym.st_shndx > SHN_UNDEF && sym->sym.st_shndx < SHN_LORESERVE) || (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) { if (sym->sym.st_shndx != SHN_XINDEX) shndx = sym->sym.st_shndx; sym->sec = find_section_by_index(elf, shndx); if (!sym->sec) { WARN("couldn't find section for symbol %s", sym->name); goto err; } if (sym->type == STT_SECTION) { sym->name = sym->sec->name; sym->sec->sym = sym; } } else sym->sec = find_section_by_index(elf, 0); sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; rb_add(&sym->sec->symbol_tree, &sym->node, symbol_to_offset); pnode = rb_prev(&sym->node); if (pnode) entry = &rb_entry(pnode, struct symbol, node)->list; else entry = &sym->sec->symbol_list; list_add(&sym->list, entry); elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx); elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name)); } if (stats) printf("nr_symbols: %lu\n", (unsigned long)symbols_nr); /* Create parent/child links for any cold subfunctions */ list_for_each_entry(sec, &elf->sections, list) { list_for_each_entry(sym, &sec->symbol_list, list) { char pname[MAX_NAME_LEN + 1]; size_t pnamelen; if (sym->type != STT_FUNC) continue; if (sym->pfunc == NULL) sym->pfunc = sym; if (sym->cfunc == NULL) sym->cfunc = sym; coldstr = strstr(sym->name, ".cold"); if (!coldstr) continue; pnamelen = coldstr - sym->name; if (pnamelen > MAX_NAME_LEN) { WARN("%s(): parent function name exceeds maximum length of %d characters", sym->name, MAX_NAME_LEN); return -1; } strncpy(pname, sym->name, pnamelen); pname[pnamelen] = '\0'; pfunc = find_symbol_by_name(elf, pname); if (!pfunc) { WARN("%s(): can't find parent function", sym->name); return -1; } sym->pfunc = pfunc; pfunc->cfunc = sym; /* * Unfortunately, -fnoreorder-functions puts the child * inside the parent. Remove the overlap so we can * have sane assumptions. * * Note that pfunc->len now no longer matches * pfunc->sym.st_size. */ if (sym->sec == pfunc->sec && sym->offset >= pfunc->offset && sym->offset + sym->len == pfunc->offset + pfunc->len) { pfunc->len -= sym->len; } } } return 0; err: free(sym); return -1;} void elf_add_reloc(struct elf *elf, struct reloc *reloc){ struct section *sec = reloc->sec; list_add_tail(&reloc->list, &sec->reloc_list); elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));} static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx){Lines 1–500 of 1017. Load more
// SPDX-License-Identifier: GPL-2.0-or-later /* * elf.c - ELF access library * * Adapted from kpatch (https://github.com/dynup/kpatch): * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com> * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> */ #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <errno.h> #include "builtin.h" #include "elf.h" #include "warn.h" #define MAX_NAME_LEN 128 static inline u32 str_hash(const char *str) { return jhash(str, strlen(str), 0); } static inline int elf_hash_bits(void) { return vmlinux ? ELF_HASH_BITS : 16; } #define elf_hash_add(hashtable, node, key) \ hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())]) static void elf_hash_init(struct hlist_head *table) { __hash_init(table, 1U << elf_hash_bits()); } #define elf_hash_for_each_possible(name, obj, member, key) \ hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member) static void rb_add(struct rb_root *tree, struct rb_node *node, int (*cmp)(struct rb_node *, const struct rb_node *)) { struct rb_node **link = &tree->rb_node; struct rb_node *parent = NULL; while (*link) { parent = *link; if (cmp(node, parent) < 0) link = &parent->rb_left; else link = &parent->rb_right; } rb_link_node(node, parent, link); rb_insert_color(node, tree); } static struct rb_node *rb_find_first(const struct rb_root *tree, const void *key, int (*cmp)(const void *key, const struct rb_node *)) { struct rb_node *node = tree->rb_node; struct rb_node *match = NULL; while (node) { int c = cmp(key, node); if (c <= 0) { if (!c) match = node; node = node->rb_left; } else if (c > 0) { node = node->rb_right; } } return match; } static struct rb_node *rb_next_match(struct rb_node *node, const void *key, int (*cmp)(const void *key, const struct rb_node *)) { node = rb_next(node); if (node && cmp(key, node)) node = NULL; return node; } #define rb_for_each(tree, node, key, cmp) \ for ((node) = rb_find_first((tree), (key), (cmp)); \ (node); (node) = rb_next_match((node), (key), (cmp))) static int symbol_to_offset(struct rb_node *a, const struct rb_node *b) { struct symbol *sa = rb_entry(a, struct symbol, node); struct symbol *sb = rb_entry(b, struct symbol, node); if (sa->offset < sb->offset) return -1; if (sa->offset > sb->offset) return 1; if (sa->len < sb->len) return -1; if (sa->len > sb->len) return 1; sa->alias = sb; return 0; } static int symbol_by_offset(const void *key, const struct rb_node *node) { const struct symbol *s = rb_entry(node, struct symbol, node); const unsigned long *o = key; if (*o < s->offset) return -1; if (*o >= s->offset + s->len) return 1; return 0; } struct section *find_section_by_name(const struct elf *elf, const char *name) { struct section *sec; elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name)) if (!strcmp(sec->name, name)) return sec; return NULL; } static struct section *find_section_by_index(struct elf *elf, unsigned int idx) { struct section *sec; elf_hash_for_each_possible(elf->section_hash, sec, hash, idx) if (sec->idx == idx) return sec; return NULL; } static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) { struct symbol *sym; elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx) if (sym->idx == idx) return sym; return NULL; } struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset) { struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->offset == offset && s->type != STT_SECTION) return s; } return NULL; } struct symbol *find_func_by_offset(struct section *sec, unsigned long offset) { struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->offset == offset && s->type == STT_FUNC) return s; } return NULL; } struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset) { struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->type != STT_SECTION) return s; } return NULL; } struct symbol *find_func_containing(struct section *sec, unsigned long offset) { struct rb_node *node; rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->type == STT_FUNC) return s; } return NULL; } struct symbol *find_symbol_by_name(const struct elf *elf, const char *name) { struct symbol *sym; elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name)) if (!strcmp(sym->name, name)) return sym; return NULL; } struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec, unsigned long offset, unsigned int len) { struct reloc *reloc, *r = NULL; unsigned long o; if (!sec->reloc) return NULL; sec = sec->reloc; for_offset_range(o, offset, offset + len) { elf_hash_for_each_possible(elf->reloc_hash, reloc, hash, sec_offset_hash(sec, o)) { if (reloc->sec != sec) continue; if (reloc->offset >= offset && reloc->offset < offset + len) { if (!r || reloc->offset < r->offset) r = reloc; } } if (r) return r; } return NULL; } struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset) { return find_reloc_by_dest_range(elf, sec, offset, 1); } static int read_sections(struct elf *elf) { Elf_Scn *s = NULL; struct section *sec; size_t shstrndx, sections_nr; int i; if (elf_getshdrnum(elf->elf, §ions_nr)) { WARN_ELF("elf_getshdrnum"); return -1; } if (elf_getshdrstrndx(elf->elf, &shstrndx)) { WARN_ELF("elf_getshdrstrndx"); return -1; } for (i = 0; i < sections_nr; i++) { sec = malloc(sizeof(*sec)); if (!sec) { perror("malloc"); return -1; } memset(sec, 0, sizeof(*sec)); INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->reloc_list); s = elf_getscn(elf->elf, i); if (!s) { WARN_ELF("elf_getscn"); return -1; } sec->idx = elf_ndxscn(s); if (!gelf_getshdr(s, &sec->sh)) { WARN_ELF("gelf_getshdr"); return -1; } sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); if (!sec->name) { WARN_ELF("elf_strptr"); return -1; } if (sec->sh.sh_size != 0) { sec->data = elf_getdata(s, NULL); if (!sec->data) { WARN_ELF("elf_getdata"); return -1; } if (sec->data->d_off != 0 || sec->data->d_size != sec->sh.sh_size) { WARN("unexpected data attributes for %s", sec->name); return -1; } } sec->len = sec->sh.sh_size; list_add_tail(&sec->list, &elf->sections); elf_hash_add(elf->section_hash, &sec->hash, sec->idx); elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name)); } if (stats) printf("nr_sections: %lu\n", (unsigned long)sections_nr); /* sanity check, one more call to elf_nextscn() should return NULL */ if (elf_nextscn(elf->elf, s)) { WARN("section entry mismatch"); return -1; } return 0; } static int read_symbols(struct elf *elf) { struct section *symtab, *symtab_shndx, *sec; struct symbol *sym, *pfunc; struct list_head *entry; struct rb_node *pnode; int symbols_nr, i; char *coldstr; Elf_Data *shndx_data = NULL; Elf32_Word shndx; symtab = find_section_by_name(elf, ".symtab"); if (!symtab) { WARN("missing symbol table"); return -1; } symtab_shndx = find_section_by_name(elf, ".symtab_shndx"); if (symtab_shndx) shndx_data = symtab_shndx->data; symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; for (i = 0; i < symbols_nr; i++) { sym = malloc(sizeof(*sym)); if (!sym) { perror("malloc"); return -1; } memset(sym, 0, sizeof(*sym)); sym->alias = sym; sym->idx = i; if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym, &shndx)) { WARN_ELF("gelf_getsymshndx"); goto err; } sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, sym->sym.st_name); if (!sym->name) { WARN_ELF("elf_strptr"); goto err; } sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); if ((sym->sym.st_shndx > SHN_UNDEF && sym->sym.st_shndx < SHN_LORESERVE) || (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) { if (sym->sym.st_shndx != SHN_XINDEX) shndx = sym->sym.st_shndx; sym->sec = find_section_by_index(elf, shndx); if (!sym->sec) { WARN("couldn't find section for symbol %s", sym->name); goto err; } if (sym->type == STT_SECTION) { sym->name = sym->sec->name; sym->sec->sym = sym; } } else sym->sec = find_section_by_index(elf, 0); sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; rb_add(&sym->sec->symbol_tree, &sym->node, symbol_to_offset); pnode = rb_prev(&sym->node); if (pnode) entry = &rb_entry(pnode, struct symbol, node)->list; else entry = &sym->sec->symbol_list; list_add(&sym->list, entry); elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx); elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name)); } if (stats) printf("nr_symbols: %lu\n", (unsigned long)symbols_nr); /* Create parent/child links for any cold subfunctions */ list_for_each_entry(sec, &elf->sections, list) { list_for_each_entry(sym, &sec->symbol_list, list) { char pname[MAX_NAME_LEN + 1]; size_t pnamelen; if (sym->type != STT_FUNC) continue; if (sym->pfunc == NULL) sym->pfunc = sym; if (sym->cfunc == NULL) sym->cfunc = sym; coldstr = strstr(sym->name, ".cold"); if (!coldstr) continue; pnamelen = coldstr - sym->name; if (pnamelen > MAX_NAME_LEN) { WARN("%s(): parent function name exceeds maximum length of %d characters", sym->name, MAX_NAME_LEN); return -1; } strncpy(pname, sym->name, pnamelen); pname[pnamelen] = '\0'; pfunc = find_symbol_by_name(elf, pname); if (!pfunc) { WARN("%s(): can't find parent function", sym->name); return -1; } sym->pfunc = pfunc; pfunc->cfunc = sym; /* * Unfortunately, -fnoreorder-functions puts the child * inside the parent. Remove the overlap so we can * have sane assumptions. * * Note that pfunc->len now no longer matches * pfunc->sym.st_size. */ if (sym->sec == pfunc->sec && sym->offset >= pfunc->offset && sym->offset + sym->len == pfunc->offset + pfunc->len) { pfunc->len -= sym->len; } } } return 0; err: free(sym); return -1; } void elf_add_reloc(struct elf *elf, struct reloc *reloc) { struct section *sec = reloc->sec; list_add_tail(&reloc->list, &sec->reloc_list); elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc)); } static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx) {