// 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 <sys/mman.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <errno.h>#include <objtool/builtin.h> #include <objtool/elf.h>#include <objtool/warn.h> #define MAX_NAME_LEN 128 static inline u32 str_hash(const char *str){ return jhash(str, strlen(str), 0);} #define __elf_table(name) (elf->name##_hash)#define __elf_bits(name) (elf->name##_bits) #define elf_hash_add(name, node, key) \ hlist_add_head(node, &__elf_table(name)[hash_min(key, __elf_bits(name))]) #define elf_hash_for_each_possible(name, obj, member, key) \ hlist_for_each_entry(obj, &__elf_table(name)[hash_min(key, __elf_bits(name))], member) #define elf_alloc_hash(name, size) \({ \ __elf_bits(name) = max(10, ilog2(size)); \ __elf_table(name) = mmap(NULL, sizeof(struct hlist_head) << __elf_bits(name), \ PROT_READ|PROT_WRITE, \ MAP_PRIVATE|MAP_ANON, -1, 0); \ if (__elf_table(name) == (void *)-1L) { \ WARN("mmap fail " #name); \ __elf_table(name) = NULL; \ } \ __elf_table(name); \}) static bool 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 true; if (sa->offset > sb->offset) return false; if (sa->len < sb->len) return true; if (sa->len > sb->len) return false; sa->alias = sb; return false;} 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 symbol_hole { unsigned long key; const struct symbol *sym;}; /* * Find !section symbol where @offset is after it. */static int symbol_hole_by_offset(const void *key, const struct rb_node *node){ const struct symbol *s = rb_entry(node, struct symbol, node); struct symbol_hole *sh = (void *)key; if (sh->key < s->offset) return -1; if (sh->key >= s->offset + s->len) { if (s->type != STT_SECTION) sh->sym = s; 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(section_name, 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(section, 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(symbol, 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(node, &offset, &sec->symbol_tree, 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(node, &offset, &sec->symbol_tree, 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(node, &offset, &sec->symbol_tree, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->type != STT_SECTION) return s; } return NULL;} /* * Returns size of hole starting at @offset. */int find_symbol_hole_containing(const struct section *sec, unsigned long offset){ struct symbol_hole hole = { .key = offset, .sym = NULL, }; struct rb_node *n; struct symbol *s; /* * Find the rightmost symbol for which @offset is after it. */ n = rb_find(&hole, &sec->symbol_tree, symbol_hole_by_offset); /* found a symbol that contains @offset */ if (n) return 0; /* not a hole */ /* didn't find a symbol for which @offset is after it */ if (!hole.sym) return 0; /* not a hole */ /* @offset >= sym->offset + sym->len, find symbol after it */ n = rb_next(&hole.sym->node); if (!n) return -1; /* until end of address space */ /* hole until start of next symbol */ s = rb_entry(n, struct symbol, node); return s->offset - offset;} struct symbol *find_func_containing(struct section *sec, unsigned long offset){ struct rb_node *node; rb_for_each(node, &offset, &sec->symbol_tree, 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(symbol_name, 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(reloc, 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; } if (!elf_alloc_hash(section, sections_nr) || !elf_alloc_hash(section_name, sections_nr)) 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; } } if (sec->sh.sh_flags & SHF_EXECINSTR) elf->text_size += sec->sh.sh_size; list_add_tail(&sec->list, &elf->sections); elf_hash_add(section, &sec->hash, sec->idx); elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name)); } if (stats) { printf("nr_sections: %lu\n", (unsigned long)sections_nr); printf("section_bits: %d\n", elf->section_bits); } /* 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 void elf_add_symbol(struct elf *elf, struct symbol *sym){ struct list_head *entry; struct rb_node *pnode; sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; rb_add(&sym->node, &sym->sec->symbol_tree, 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(symbol, &sym->hash, sym->idx); elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name)); /* * Don't store empty STT_NOTYPE symbols in the rbtree. They * can exist within a function, confusing the sorting. */ if (!sym->len) rb_erase(&sym->node, &sym->sec->symbol_tree);} static int read_symbols(struct elf *elf){ struct section *symtab, *symtab_shndx, *sec; struct symbol *sym, *pfunc; int symbols_nr, i; char *coldstr; Elf_Data *shndx_data = NULL; Elf32_Word shndx; symtab = find_section_by_name(elf, ".symtab"); if (symtab) { 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; } else { /* * A missing symbol table is actually possible if it's an empty * .o file. This can happen for thunk_64.o. Make sure to at * least allocate the symbol hash tables so we can do symbol * lookups without crashing. */ symbols_nr = 0; } if (!elf_alloc_hash(symbol, symbols_nr) || !elf_alloc_hash(symbol_name, symbols_nr)) return -1; for (i = 0; i < symbols_nr; i++) { sym = malloc(sizeof(*sym)); if (!sym) { perror("malloc"); return -1; } memset(sym, 0, sizeof(*sym)); INIT_LIST_HEAD(&sym->pv_target); 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; } 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 (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) { sym->name = sym->sec->name; sym->sec->sym = sym; } } else sym->sec = find_section_by_index(elf, 0); elf_add_symbol(elf, sym); } if (stats) { printf("nr_symbols: %lu\n", (unsigned long)symbols_nr); printf("symbol_bits: %d\n", elf->symbol_bits); } /* 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; Lines 1–500 of 1294. 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 <sys/mman.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <errno.h> #include <objtool/builtin.h> #include <objtool/elf.h> #include <objtool/warn.h> #define MAX_NAME_LEN 128 static inline u32 str_hash(const char *str) { return jhash(str, strlen(str), 0); } #define __elf_table(name) (elf->name##_hash) #define __elf_bits(name) (elf->name##_bits) #define elf_hash_add(name, node, key) \ hlist_add_head(node, &__elf_table(name)[hash_min(key, __elf_bits(name))]) #define elf_hash_for_each_possible(name, obj, member, key) \ hlist_for_each_entry(obj, &__elf_table(name)[hash_min(key, __elf_bits(name))], member) #define elf_alloc_hash(name, size) \ ({ \ __elf_bits(name) = max(10, ilog2(size)); \ __elf_table(name) = mmap(NULL, sizeof(struct hlist_head) << __elf_bits(name), \ PROT_READ|PROT_WRITE, \ MAP_PRIVATE|MAP_ANON, -1, 0); \ if (__elf_table(name) == (void *)-1L) { \ WARN("mmap fail " #name); \ __elf_table(name) = NULL; \ } \ __elf_table(name); \ }) static bool 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 true; if (sa->offset > sb->offset) return false; if (sa->len < sb->len) return true; if (sa->len > sb->len) return false; sa->alias = sb; return false; } 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 symbol_hole { unsigned long key; const struct symbol *sym; }; /* * Find !section symbol where @offset is after it. */ static int symbol_hole_by_offset(const void *key, const struct rb_node *node) { const struct symbol *s = rb_entry(node, struct symbol, node); struct symbol_hole *sh = (void *)key; if (sh->key < s->offset) return -1; if (sh->key >= s->offset + s->len) { if (s->type != STT_SECTION) sh->sym = s; 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(section_name, 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(section, 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(symbol, 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(node, &offset, &sec->symbol_tree, 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(node, &offset, &sec->symbol_tree, 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(node, &offset, &sec->symbol_tree, symbol_by_offset) { struct symbol *s = rb_entry(node, struct symbol, node); if (s->type != STT_SECTION) return s; } return NULL; } /* * Returns size of hole starting at @offset. */ int find_symbol_hole_containing(const struct section *sec, unsigned long offset) { struct symbol_hole hole = { .key = offset, .sym = NULL, }; struct rb_node *n; struct symbol *s; /* * Find the rightmost symbol for which @offset is after it. */ n = rb_find(&hole, &sec->symbol_tree, symbol_hole_by_offset); /* found a symbol that contains @offset */ if (n) return 0; /* not a hole */ /* didn't find a symbol for which @offset is after it */ if (!hole.sym) return 0; /* not a hole */ /* @offset >= sym->offset + sym->len, find symbol after it */ n = rb_next(&hole.sym->node); if (!n) return -1; /* until end of address space */ /* hole until start of next symbol */ s = rb_entry(n, struct symbol, node); return s->offset - offset; } struct symbol *find_func_containing(struct section *sec, unsigned long offset) { struct rb_node *node; rb_for_each(node, &offset, &sec->symbol_tree, 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(symbol_name, 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(reloc, 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; } if (!elf_alloc_hash(section, sections_nr) || !elf_alloc_hash(section_name, sections_nr)) 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; } } if (sec->sh.sh_flags & SHF_EXECINSTR) elf->text_size += sec->sh.sh_size; list_add_tail(&sec->list, &elf->sections); elf_hash_add(section, &sec->hash, sec->idx); elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name)); } if (stats) { printf("nr_sections: %lu\n", (unsigned long)sections_nr); printf("section_bits: %d\n", elf->section_bits); } /* 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 void elf_add_symbol(struct elf *elf, struct symbol *sym) { struct list_head *entry; struct rb_node *pnode; sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; rb_add(&sym->node, &sym->sec->symbol_tree, 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(symbol, &sym->hash, sym->idx); elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name)); /* * Don't store empty STT_NOTYPE symbols in the rbtree. They * can exist within a function, confusing the sorting. */ if (!sym->len) rb_erase(&sym->node, &sym->sec->symbol_tree); } static int read_symbols(struct elf *elf) { struct section *symtab, *symtab_shndx, *sec; struct symbol *sym, *pfunc; int symbols_nr, i; char *coldstr; Elf_Data *shndx_data = NULL; Elf32_Word shndx; symtab = find_section_by_name(elf, ".symtab"); if (symtab) { 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; } else { /* * A missing symbol table is actually possible if it's an empty * .o file. This can happen for thunk_64.o. Make sure to at * least allocate the symbol hash tables so we can do symbol * lookups without crashing. */ symbols_nr = 0; } if (!elf_alloc_hash(symbol, symbols_nr) || !elf_alloc_hash(symbol_name, symbols_nr)) return -1; for (i = 0; i < symbols_nr; i++) { sym = malloc(sizeof(*sym)); if (!sym) { perror("malloc"); return -1; } memset(sym, 0, sizeof(*sym)); INIT_LIST_HEAD(&sym->pv_target); 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; } 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 (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) { sym->name = sym->sec->name; sym->sec->sym = sym; } } else sym->sec = find_section_by_index(elf, 0); elf_add_symbol(elf, sym); } if (stats) { printf("nr_symbols: %lu\n", (unsigned long)symbols_nr); printf("symbol_bits: %d\n", elf->symbol_bits); } /* 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;