mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-28 20:02:17 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
kernel tooling such as kpatch-build.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=MvPd
-----END PGP SIGNATURE-----
mergetag object d33b9035e1
type commit
tag objtool-core-2021-06-28
tagger Ingo Molnar <mingo@kernel.org> 1624859477 +0200
The biggest change in this cycle is the new code to handle
and rewrite variable sized jump labels - which results in
slightly tighter code generation in hot paths, through the
use of short(er) NOPs.
Also a number of cleanups and fixes, and a change to the
generic include/linux/compiler.h to handle a s390 GCC quirk.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=+HAB
-----END PGP SIGNATURE-----
Merge tags 'objtool-urgent-2021-06-28' and 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fix and updates from Ingo Molnar:
"An ELF format fix for a section flags mismatch bug that breaks kernel
tooling such as kpatch-build.
The biggest change in this cycle is the new code to handle and rewrite
variable sized jump labels - which results in slightly tighter code
generation in hot paths, through the use of short(er) NOPs.
Also a number of cleanups and fixes, and a change to the generic
include/linux/compiler.h to handle a s390 GCC quirk"
* tag 'objtool-urgent-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Don't make .altinstructions writable
* tag 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Improve reloc hash size guestimate
instrumentation.h: Avoid using inline asm operand modifiers
compiler.h: Avoid using inline asm operand modifiers
kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> := n'
objtool: Reflow handle_jump_alt()
jump_label/x86: Remove unused JUMP_LABEL_NOP_SIZE
jump_label, x86: Allow short NOPs
objtool: Provide stats for jump_labels
objtool: Rewrite jump_label instructions
objtool: Decode jump_entry::key addend
jump_label, x86: Emit short JMP
jump_label: Free jump_entry::key bit1 for build use
jump_label, x86: Add variable length patching support
jump_label, x86: Introduce jump_entry_size()
jump_label, x86: Improve error when we fail expected text
jump_label, x86: Factor out the __jump_table generation
jump_label, x86: Strip ASM jump_label support
x86, objtool: Dont exclude arch/x86/realmode/
objtool: Rewrite hashtable sizing
1179 lines
25 KiB
C
1179 lines
25 KiB
C
// 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 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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
}
|
|
sec->len = sec->sh.sh_size;
|
|
|
|
if (sec->sh.sh_flags & SHF_EXECINSTR)
|
|
elf->text_size += sec->len;
|
|
|
|
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));
|
|
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;
|
|
|
|
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 struct section *elf_create_reloc_section(struct elf *elf,
|
|
struct section *base,
|
|
int reltype);
|
|
|
|
int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
|
|
unsigned int type, struct symbol *sym, int addend)
|
|
{
|
|
struct reloc *reloc;
|
|
|
|
if (!sec->reloc && !elf_create_reloc_section(elf, sec, SHT_RELA))
|
|
return -1;
|
|
|
|
reloc = malloc(sizeof(*reloc));
|
|
if (!reloc) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
memset(reloc, 0, sizeof(*reloc));
|
|
|
|
reloc->sec = sec->reloc;
|
|
reloc->offset = offset;
|
|
reloc->type = type;
|
|
reloc->sym = sym;
|
|
reloc->addend = addend;
|
|
|
|
list_add_tail(&reloc->list, &sec->reloc->reloc_list);
|
|
elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
|
|
|
|
sec->reloc->changed = true;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
|
|
unsigned long offset, unsigned int type,
|
|
struct section *insn_sec, unsigned long insn_off)
|
|
{
|
|
struct symbol *sym;
|
|
int addend;
|
|
|
|
if (insn_sec->sym) {
|
|
sym = insn_sec->sym;
|
|
addend = insn_off;
|
|
|
|
} else {
|
|
/*
|
|
* The Clang assembler strips section symbols, so we have to
|
|
* reference the function symbol instead:
|
|
*/
|
|
sym = find_symbol_containing(insn_sec, insn_off);
|
|
if (!sym) {
|
|
/*
|
|
* Hack alert. This happens when we need to reference
|
|
* the NOP pad insn immediately after the function.
|
|
*/
|
|
sym = find_symbol_containing(insn_sec, insn_off - 1);
|
|
}
|
|
|
|
if (!sym) {
|
|
WARN("can't find symbol containing %s+0x%lx", insn_sec->name, insn_off);
|
|
return -1;
|
|
}
|
|
|
|
addend = insn_off - sym->offset;
|
|
}
|
|
|
|
return elf_add_reloc(elf, sec, offset, type, sym, addend);
|
|
}
|
|
|
|
static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
|
|
{
|
|
if (!gelf_getrel(sec->data, i, &reloc->rel)) {
|
|
WARN_ELF("gelf_getrel");
|
|
return -1;
|
|
}
|
|
reloc->type = GELF_R_TYPE(reloc->rel.r_info);
|
|
reloc->addend = 0;
|
|
reloc->offset = reloc->rel.r_offset;
|
|
*symndx = GELF_R_SYM(reloc->rel.r_info);
|
|
return 0;
|
|
}
|
|
|
|
static int read_rela_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
|
|
{
|
|
if (!gelf_getrela(sec->data, i, &reloc->rela)) {
|
|
WARN_ELF("gelf_getrela");
|
|
return -1;
|
|
}
|
|
reloc->type = GELF_R_TYPE(reloc->rela.r_info);
|
|
reloc->addend = reloc->rela.r_addend;
|
|
reloc->offset = reloc->rela.r_offset;
|
|
*symndx = GELF_R_SYM(reloc->rela.r_info);
|
|
return 0;
|
|
}
|
|
|
|
static int read_relocs(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
struct reloc *reloc;
|
|
int i;
|
|
unsigned int symndx;
|
|
unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
|
|
|
|
if (!elf_alloc_hash(reloc, elf->text_size / 16))
|
|
return -1;
|
|
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if ((sec->sh.sh_type != SHT_RELA) &&
|
|
(sec->sh.sh_type != SHT_REL))
|
|
continue;
|
|
|
|
sec->base = find_section_by_index(elf, sec->sh.sh_info);
|
|
if (!sec->base) {
|
|
WARN("can't find base section for reloc section %s",
|
|
sec->name);
|
|
return -1;
|
|
}
|
|
|
|
sec->base->reloc = sec;
|
|
|
|
nr_reloc = 0;
|
|
for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
|
|
reloc = malloc(sizeof(*reloc));
|
|
if (!reloc) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
memset(reloc, 0, sizeof(*reloc));
|
|
switch (sec->sh.sh_type) {
|
|
case SHT_REL:
|
|
if (read_rel_reloc(sec, i, reloc, &symndx))
|
|
return -1;
|
|
break;
|
|
case SHT_RELA:
|
|
if (read_rela_reloc(sec, i, reloc, &symndx))
|
|
return -1;
|
|
break;
|
|
default: return -1;
|
|
}
|
|
|
|
reloc->sec = sec;
|
|
reloc->idx = i;
|
|
reloc->sym = find_symbol_by_index(elf, symndx);
|
|
if (!reloc->sym) {
|
|
WARN("can't find reloc entry symbol %d for %s",
|
|
symndx, sec->name);
|
|
return -1;
|
|
}
|
|
|
|
list_add_tail(&reloc->list, &sec->reloc_list);
|
|
elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
|
|
|
|
nr_reloc++;
|
|
}
|
|
max_reloc = max(max_reloc, nr_reloc);
|
|
tot_reloc += nr_reloc;
|
|
}
|
|
|
|
if (stats) {
|
|
printf("max_reloc: %lu\n", max_reloc);
|
|
printf("tot_reloc: %lu\n", tot_reloc);
|
|
printf("reloc_bits: %d\n", elf->reloc_bits);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct elf *elf_open_read(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, offsetof(struct elf, sections));
|
|
|
|
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_relocs(elf))
|
|
goto err;
|
|
|
|
return elf;
|
|
|
|
err:
|
|
elf_close(elf);
|
|
return NULL;
|
|
}
|
|
|
|
static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
|
|
{
|
|
Elf_Data *data;
|
|
Elf_Scn *s;
|
|
int len;
|
|
|
|
if (!strtab)
|
|
strtab = find_section_by_name(elf, ".strtab");
|
|
if (!strtab) {
|
|
WARN("can't find .strtab section");
|
|
return -1;
|
|
}
|
|
|
|
s = elf_getscn(elf->elf, strtab->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return -1;
|
|
}
|
|
|
|
data = elf_newdata(s);
|
|
if (!data) {
|
|
WARN_ELF("elf_newdata");
|
|
return -1;
|
|
}
|
|
|
|
data->d_buf = str;
|
|
data->d_size = strlen(str) + 1;
|
|
data->d_align = 1;
|
|
|
|
len = strtab->len;
|
|
strtab->len += data->d_size;
|
|
strtab->changed = true;
|
|
|
|
return len;
|
|
}
|
|
|
|
struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
|
|
{
|
|
struct section *symtab, *symtab_shndx;
|
|
struct symbol *sym;
|
|
Elf_Data *data;
|
|
Elf_Scn *s;
|
|
|
|
sym = malloc(sizeof(*sym));
|
|
if (!sym) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(sym, 0, sizeof(*sym));
|
|
|
|
sym->name = strdup(name);
|
|
|
|
sym->sym.st_name = elf_add_string(elf, NULL, sym->name);
|
|
if (sym->sym.st_name == -1)
|
|
return NULL;
|
|
|
|
sym->sym.st_info = GELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
|
|
// st_other 0
|
|
// st_shndx 0
|
|
// st_value 0
|
|
// st_size 0
|
|
|
|
symtab = find_section_by_name(elf, ".symtab");
|
|
if (!symtab) {
|
|
WARN("can't find .symtab");
|
|
return NULL;
|
|
}
|
|
|
|
s = elf_getscn(elf->elf, symtab->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return NULL;
|
|
}
|
|
|
|
data = elf_newdata(s);
|
|
if (!data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
data->d_buf = &sym->sym;
|
|
data->d_size = sizeof(sym->sym);
|
|
data->d_align = 1;
|
|
data->d_type = ELF_T_SYM;
|
|
|
|
sym->idx = symtab->len / sizeof(sym->sym);
|
|
|
|
symtab->len += data->d_size;
|
|
symtab->changed = true;
|
|
|
|
symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
|
|
if (symtab_shndx) {
|
|
s = elf_getscn(elf->elf, symtab_shndx->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return NULL;
|
|
}
|
|
|
|
data = elf_newdata(s);
|
|
if (!data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
data->d_buf = &sym->sym.st_size; /* conveniently 0 */
|
|
data->d_size = sizeof(Elf32_Word);
|
|
data->d_align = 4;
|
|
data->d_type = ELF_T_WORD;
|
|
|
|
symtab_shndx->len += 4;
|
|
symtab_shndx->changed = true;
|
|
}
|
|
|
|
sym->sec = find_section_by_index(elf, 0);
|
|
|
|
elf_add_symbol(elf, sym);
|
|
|
|
return sym;
|
|
}
|
|
|
|
struct section *elf_create_section(struct elf *elf, const char *name,
|
|
unsigned int sh_flags, size_t entsize, int nr)
|
|
{
|
|
struct section *sec, *shstrtab;
|
|
size_t size = entsize * nr;
|
|
Elf_Scn *s;
|
|
|
|
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->reloc_list);
|
|
|
|
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 | sh_flags;
|
|
|
|
/* 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;
|
|
}
|
|
sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
|
|
if (sec->sh.sh_name == -1)
|
|
return NULL;
|
|
|
|
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));
|
|
|
|
elf->changed = true;
|
|
|
|
return sec;
|
|
}
|
|
|
|
static struct section *elf_create_rel_reloc_section(struct elf *elf, struct section *base)
|
|
{
|
|
char *relocname;
|
|
struct section *sec;
|
|
|
|
relocname = malloc(strlen(base->name) + strlen(".rel") + 1);
|
|
if (!relocname) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
strcpy(relocname, ".rel");
|
|
strcat(relocname, base->name);
|
|
|
|
sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rel), 0);
|
|
free(relocname);
|
|
if (!sec)
|
|
return NULL;
|
|
|
|
base->reloc = sec;
|
|
sec->base = base;
|
|
|
|
sec->sh.sh_type = SHT_REL;
|
|
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;
|
|
}
|
|
|
|
static struct section *elf_create_rela_reloc_section(struct elf *elf, struct section *base)
|
|
{
|
|
char *relocname;
|
|
struct section *sec;
|
|
|
|
relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
|
|
if (!relocname) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
strcpy(relocname, ".rela");
|
|
strcat(relocname, base->name);
|
|
|
|
sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
|
|
free(relocname);
|
|
if (!sec)
|
|
return NULL;
|
|
|
|
base->reloc = 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;
|
|
}
|
|
|
|
static struct section *elf_create_reloc_section(struct elf *elf,
|
|
struct section *base,
|
|
int reltype)
|
|
{
|
|
switch (reltype) {
|
|
case SHT_REL: return elf_create_rel_reloc_section(elf, base);
|
|
case SHT_RELA: return elf_create_rela_reloc_section(elf, base);
|
|
default: return NULL;
|
|
}
|
|
}
|
|
|
|
static int elf_rebuild_rel_reloc_section(struct section *sec, int nr)
|
|
{
|
|
struct reloc *reloc;
|
|
int idx = 0, size;
|
|
void *buf;
|
|
|
|
/* Allocate a buffer for relocations */
|
|
size = nr * sizeof(GElf_Rel);
|
|
buf = malloc(size);
|
|
if (!buf) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
|
|
sec->data->d_buf = buf;
|
|
sec->data->d_size = size;
|
|
sec->data->d_type = ELF_T_REL;
|
|
|
|
sec->sh.sh_size = size;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
reloc->rel.r_offset = reloc->offset;
|
|
reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
gelf_update_rel(sec->data, idx, &reloc->rel);
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
|
|
{
|
|
struct reloc *reloc;
|
|
int idx = 0, size;
|
|
void *buf;
|
|
|
|
/* Allocate a buffer for relocations with addends */
|
|
size = nr * sizeof(GElf_Rela);
|
|
buf = malloc(size);
|
|
if (!buf) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
|
|
sec->data->d_buf = buf;
|
|
sec->data->d_size = size;
|
|
sec->data->d_type = ELF_T_RELA;
|
|
|
|
sec->sh.sh_size = size;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
reloc->rela.r_offset = reloc->offset;
|
|
reloc->rela.r_addend = reloc->addend;
|
|
reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
gelf_update_rela(sec->data, idx, &reloc->rela);
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
|
|
{
|
|
struct reloc *reloc;
|
|
int nr;
|
|
|
|
nr = 0;
|
|
list_for_each_entry(reloc, &sec->reloc_list, list)
|
|
nr++;
|
|
|
|
switch (sec->sh.sh_type) {
|
|
case SHT_REL: return elf_rebuild_rel_reloc_section(sec, nr);
|
|
case SHT_RELA: return elf_rebuild_rela_reloc_section(sec, nr);
|
|
default: return -1;
|
|
}
|
|
}
|
|
|
|
int elf_write_insn(struct elf *elf, struct section *sec,
|
|
unsigned long offset, unsigned int len,
|
|
const char *insn)
|
|
{
|
|
Elf_Data *data = sec->data;
|
|
|
|
if (data->d_type != ELF_T_BYTE || data->d_off) {
|
|
WARN("write to unexpected data for section: %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
memcpy(data->d_buf + offset, insn, len);
|
|
elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
|
|
|
|
elf->changed = true;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_write_reloc(struct elf *elf, struct reloc *reloc)
|
|
{
|
|
struct section *sec = reloc->sec;
|
|
|
|
if (sec->sh.sh_type == SHT_REL) {
|
|
reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
reloc->rel.r_offset = reloc->offset;
|
|
|
|
if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
|
|
WARN_ELF("gelf_update_rel");
|
|
return -1;
|
|
}
|
|
} else {
|
|
reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
reloc->rela.r_addend = reloc->addend;
|
|
reloc->rela.r_offset = reloc->offset;
|
|
|
|
if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
|
|
WARN_ELF("gelf_update_rela");
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
elf->changed = true;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_write(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
Elf_Scn *s;
|
|
|
|
/* Update changed relocation sections and section headers: */
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if (sec->changed) {
|
|
if (sec->base &&
|
|
elf_rebuild_reloc_section(elf, sec)) {
|
|
WARN("elf_rebuild_reloc_section");
|
|
return -1;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
sec->changed = false;
|
|
elf->changed = true;
|
|
}
|
|
}
|
|
|
|
/* 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;
|
|
}
|
|
|
|
elf->changed = false;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void elf_close(struct elf *elf)
|
|
{
|
|
struct section *sec, *tmpsec;
|
|
struct symbol *sym, *tmpsym;
|
|
struct reloc *reloc, *tmpreloc;
|
|
|
|
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(reloc, tmpreloc, &sec->reloc_list, list) {
|
|
list_del(&reloc->list);
|
|
hash_del(&reloc->hash);
|
|
free(reloc);
|
|
}
|
|
list_del(&sec->list);
|
|
free(sec);
|
|
}
|
|
|
|
free(elf);
|
|
}
|