From 76cb841cb886eef6b3bee341a2266c76578724ad Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:30 +0200 Subject: Adding upstream version 4.19.249. Signed-off-by: Daniel Baumann --- tools/objtool/elf.c | 693 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 693 insertions(+) create mode 100644 tools/objtool/elf.c (limited to 'tools/objtool/elf.c') diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c new file mode 100644 index 000000000..264d49fea --- /dev/null +++ b/tools/objtool/elf.c @@ -0,0 +1,693 @@ +/* + * elf.c - ELF access library + * + * Adapted from kpatch (https://github.com/dynup/kpatch): + * Copyright (C) 2013-2015 Josh Poimboeuf + * Copyright (C) 2014 Seth Jennings + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see . + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "elf.h" +#include "warn.h" + +#define MAX_NAME_LEN 128 + +struct section *find_section_by_name(struct elf *elf, const char *name) +{ + struct section *sec; + + list_for_each_entry(sec, &elf->sections, list) + 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; + + list_for_each_entry(sec, &elf->sections, list) + if (sec->idx == idx) + return sec; + + return NULL; +} + +static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) +{ + struct section *sec; + struct symbol *sym; + + list_for_each_entry(sec, &elf->sections, list) + hash_for_each_possible(sec->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 symbol *sym; + + list_for_each_entry(sym, &sec->symbol_list, list) + if (sym->type != STT_SECTION && + sym->offset == offset) + return sym; + + return NULL; +} + +struct symbol *find_symbol_by_name(struct elf *elf, const char *name) +{ + struct section *sec; + struct symbol *sym; + + list_for_each_entry(sec, &elf->sections, list) + list_for_each_entry(sym, &sec->symbol_list, list) + if (!strcmp(sym->name, name)) + return sym; + + return NULL; +} + +struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) +{ + struct symbol *sym; + + list_for_each_entry(sym, &sec->symbol_list, list) + if (sym->type != STT_SECTION && + offset >= sym->offset && offset < sym->offset + sym->len) + return sym; + + return NULL; +} + +struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, + unsigned int len) +{ + struct rela *rela; + unsigned long o; + + if (!sec->rela) + return NULL; + + for (o = offset; o < offset + len; o++) + hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) + if (rela->offset == o) + return rela; + + return NULL; +} + +struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) +{ + return find_rela_by_dest_range(sec, offset, 1); +} + +struct symbol *find_containing_func(struct section *sec, unsigned long offset) +{ + struct symbol *func; + + list_for_each_entry(func, &sec->symbol_list, list) + if (func->type == STT_FUNC && offset >= func->offset && + offset < func->offset + func->len) + return func; + + return NULL; +} + +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->rela_list); + hash_init(sec->rela_hash); + hash_init(sec->symbol_hash); + + list_add_tail(&sec->list, &elf->sections); + + 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; + } + + /* 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, *sec; + struct symbol *sym, *pfunc; + struct list_head *entry, *tmp; + int symbols_nr, i; + char *coldstr; + + symtab = find_section_by_name(elf, ".symtab"); + if (!symtab) { + /* + * A missing symbol table is actually possible if it's an empty + * .o file. This can happen for thunk_64.o. + */ + return 0; + } + + 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->idx = i; + + if (!gelf_getsym(symtab->data, i, &sym->sym)) { + WARN_ELF("gelf_getsym"); + 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) { + sym->sec = find_section_by_index(elf, + sym->sym.st_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; + + /* sorted insert into a per-section list */ + entry = &sym->sec->symbol_list; + list_for_each_prev(tmp, &sym->sec->symbol_list) { + struct symbol *s; + + s = list_entry(tmp, struct symbol, list); + + if (sym->offset > s->offset) { + entry = tmp; + break; + } + + if (sym->offset == s->offset && sym->len >= s->len) { + entry = tmp; + break; + } + } + list_add(&sym->list, entry); + hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); + } + + /* 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; + sym->pfunc = 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; +} + +static int read_relas(struct elf *elf) +{ + struct section *sec; + struct rela *rela; + int i; + unsigned int symndx; + + list_for_each_entry(sec, &elf->sections, list) { + if (sec->sh.sh_type != SHT_RELA) + continue; + + sec->base = find_section_by_name(elf, sec->name + 5); + if (!sec->base) { + WARN("can't find base section for rela section %s", + sec->name); + return -1; + } + + sec->base->rela = sec; + + for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { + rela = malloc(sizeof(*rela)); + if (!rela) { + perror("malloc"); + return -1; + } + memset(rela, 0, sizeof(*rela)); + + if (!gelf_getrela(sec->data, i, &rela->rela)) { + WARN_ELF("gelf_getrela"); + return -1; + } + + rela->type = GELF_R_TYPE(rela->rela.r_info); + rela->addend = rela->rela.r_addend; + rela->offset = rela->rela.r_offset; + symndx = GELF_R_SYM(rela->rela.r_info); + rela->sym = find_symbol_by_index(elf, symndx); + rela->rela_sec = sec; + if (!rela->sym) { + WARN("can't find rela entry symbol %d for %s", + symndx, sec->name); + return -1; + } + + list_add_tail(&rela->list, &sec->rela_list); + hash_add(sec->rela_hash, &rela->hash, rela->offset); + + } + } + + return 0; +} + +struct elf *elf_open(const char *name, int flags) +{ + struct elf *elf; + Elf_Cmd cmd; + + elf_version(EV_CURRENT); + + elf = malloc(sizeof(*elf)); + if (!elf) { + perror("malloc"); + return NULL; + } + memset(elf, 0, sizeof(*elf)); + + INIT_LIST_HEAD(&elf->sections); + + elf->fd = open(name, flags); + if (elf->fd == -1) { + fprintf(stderr, "objtool: Can't open '%s': %s\n", + name, strerror(errno)); + goto err; + } + + if ((flags & O_ACCMODE) == O_RDONLY) + cmd = ELF_C_READ_MMAP; + else if ((flags & O_ACCMODE) == O_RDWR) + cmd = ELF_C_RDWR; + else /* O_WRONLY */ + cmd = ELF_C_WRITE; + + elf->elf = elf_begin(elf->fd, cmd, NULL); + if (!elf->elf) { + WARN_ELF("elf_begin"); + goto err; + } + + if (!gelf_getehdr(elf->elf, &elf->ehdr)) { + WARN_ELF("gelf_getehdr"); + goto err; + } + + if (read_sections(elf)) + goto err; + + if (read_symbols(elf)) + goto err; + + if (read_relas(elf)) + goto err; + + return elf; + +err: + elf_close(elf); + return NULL; +} + +struct section *elf_create_section(struct elf *elf, const char *name, + size_t entsize, int nr) +{ + struct section *sec, *shstrtab; + size_t size = entsize * nr; + struct Elf_Scn *s; + Elf_Data *data; + + sec = malloc(sizeof(*sec)); + if (!sec) { + perror("malloc"); + return NULL; + } + memset(sec, 0, sizeof(*sec)); + + INIT_LIST_HEAD(&sec->symbol_list); + INIT_LIST_HEAD(&sec->rela_list); + hash_init(sec->rela_hash); + hash_init(sec->symbol_hash); + + list_add_tail(&sec->list, &elf->sections); + + s = elf_newscn(elf->elf); + if (!s) { + WARN_ELF("elf_newscn"); + return NULL; + } + + sec->name = strdup(name); + if (!sec->name) { + perror("strdup"); + return NULL; + } + + sec->idx = elf_ndxscn(s); + sec->len = size; + sec->changed = true; + + sec->data = elf_newdata(s); + if (!sec->data) { + WARN_ELF("elf_newdata"); + return NULL; + } + + sec->data->d_size = size; + sec->data->d_align = 1; + + if (size) { + sec->data->d_buf = malloc(size); + if (!sec->data->d_buf) { + perror("malloc"); + return NULL; + } + memset(sec->data->d_buf, 0, size); + } + + if (!gelf_getshdr(s, &sec->sh)) { + WARN_ELF("gelf_getshdr"); + return NULL; + } + + sec->sh.sh_size = size; + sec->sh.sh_entsize = entsize; + sec->sh.sh_type = SHT_PROGBITS; + sec->sh.sh_addralign = 1; + sec->sh.sh_flags = SHF_ALLOC; + + + /* Add section name to .shstrtab (or .strtab for Clang) */ + shstrtab = find_section_by_name(elf, ".shstrtab"); + if (!shstrtab) + shstrtab = find_section_by_name(elf, ".strtab"); + if (!shstrtab) { + WARN("can't find .shstrtab or .strtab section"); + return NULL; + } + + s = elf_getscn(elf->elf, shstrtab->idx); + if (!s) { + WARN_ELF("elf_getscn"); + return NULL; + } + + data = elf_newdata(s); + if (!data) { + WARN_ELF("elf_newdata"); + return NULL; + } + + data->d_buf = sec->name; + data->d_size = strlen(name) + 1; + data->d_align = 1; + + sec->sh.sh_name = shstrtab->len; + + shstrtab->len += strlen(name) + 1; + shstrtab->changed = true; + + return sec; +} + +struct section *elf_create_rela_section(struct elf *elf, struct section *base) +{ + char *relaname; + struct section *sec; + + relaname = malloc(strlen(base->name) + strlen(".rela") + 1); + if (!relaname) { + perror("malloc"); + return NULL; + } + strcpy(relaname, ".rela"); + strcat(relaname, base->name); + + sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0); + free(relaname); + if (!sec) + return NULL; + + base->rela = sec; + sec->base = base; + + sec->sh.sh_type = SHT_RELA; + sec->sh.sh_addralign = 8; + sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx; + sec->sh.sh_info = base->idx; + sec->sh.sh_flags = SHF_INFO_LINK; + + return sec; +} + +int elf_rebuild_rela_section(struct section *sec) +{ + struct rela *rela; + int nr, idx = 0, size; + GElf_Rela *relas; + + nr = 0; + list_for_each_entry(rela, &sec->rela_list, list) + nr++; + + size = nr * sizeof(*relas); + relas = malloc(size); + if (!relas) { + perror("malloc"); + return -1; + } + + sec->data->d_buf = relas; + sec->data->d_size = size; + + sec->sh.sh_size = size; + + idx = 0; + list_for_each_entry(rela, &sec->rela_list, list) { + relas[idx].r_offset = rela->offset; + relas[idx].r_addend = rela->addend; + relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type); + idx++; + } + + return 0; +} + +int elf_write(struct elf *elf) +{ + struct section *sec; + Elf_Scn *s; + + /* Update section headers for changed sections: */ + list_for_each_entry(sec, &elf->sections, list) { + if (sec->changed) { + s = elf_getscn(elf->elf, sec->idx); + if (!s) { + WARN_ELF("elf_getscn"); + return -1; + } + if (!gelf_update_shdr(s, &sec->sh)) { + WARN_ELF("gelf_update_shdr"); + return -1; + } + } + } + + /* Make sure the new section header entries get updated properly. */ + elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY); + + /* Write all changes to the file. */ + if (elf_update(elf->elf, ELF_C_WRITE) < 0) { + WARN_ELF("elf_update"); + return -1; + } + + return 0; +} + +void elf_close(struct elf *elf) +{ + struct section *sec, *tmpsec; + struct symbol *sym, *tmpsym; + struct rela *rela, *tmprela; + + if (elf->elf) + elf_end(elf->elf); + + if (elf->fd > 0) + close(elf->fd); + + list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) { + list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) { + list_del(&sym->list); + hash_del(&sym->hash); + free(sym); + } + list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) { + list_del(&rela->list); + hash_del(&rela->hash); + free(rela); + } + list_del(&sec->list); + free(sec); + } + + free(elf); +} -- cgit v1.2.3