objtool: Add elf_create_section_pair()

When creating an annotation section, allocate the reloc section data at
the beginning.  This simplifies the data model a bit and also saves
memory due to the removal of malloc() in elf_rebuild_reloc_section().

With allyesconfig + CONFIG_DEBUG_INFO:

- Before: peak heap memory consumption: 53.49G
- After:  peak heap memory consumption: 49.02G

Link: https://lore.kernel.org/r/048e908f3ede9b66c15e44672b6dda992b1dae3e.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2023-05-30 10:20:59 -07:00
parent ff4082730c
commit 6342a20efb
6 changed files with 184 additions and 157 deletions

View File

@ -1,10 +1,13 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _OBJTOOL_ARCH_ELF
#define _OBJTOOL_ARCH_ELF
#define R_NONE R_PPC_NONE
#define R_ABS64 R_PPC64_ADDR64
#define R_ABS32 R_PPC_ADDR32
#define R_NONE R_PPC_NONE
#define R_ABS64 R_PPC64_ADDR64
#define R_ABS32 R_PPC_ADDR32
#define R_DATA32 R_PPC_REL32
#define R_DATA64 R_PPC64_REL64
#define R_TEXT32 R_PPC_REL32
#define R_TEXT64 R_PPC64_REL32
#endif /* _OBJTOOL_ARCH_ELF */

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@ -1,8 +1,13 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _OBJTOOL_ARCH_ELF
#define _OBJTOOL_ARCH_ELF
#define R_NONE R_X86_64_NONE
#define R_ABS64 R_X86_64_64
#define R_ABS32 R_X86_64_32
#define R_NONE R_X86_64_NONE
#define R_ABS32 R_X86_64_32
#define R_ABS64 R_X86_64_64
#define R_DATA32 R_X86_64_PC32
#define R_DATA64 R_X86_64_PC32
#define R_TEXT32 R_X86_64_PC32
#define R_TEXT64 R_X86_64_PC32
#endif /* _OBJTOOL_ARCH_ELF */

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@ -8,7 +8,6 @@
#include <inttypes.h>
#include <sys/mman.h>
#include <arch/elf.h>
#include <objtool/builtin.h>
#include <objtool/cfi.h>
#include <objtool/arch.h>
@ -656,8 +655,8 @@ reachable:
static int create_static_call_sections(struct objtool_file *file)
{
struct section *sec;
struct static_call_site *site;
struct section *sec;
struct instruction *insn;
struct symbol *key_sym;
char *key_name, *tmp;
@ -677,25 +676,21 @@ static int create_static_call_sections(struct objtool_file *file)
list_for_each_entry(insn, &file->static_call_list, call_node)
idx++;
sec = elf_create_section(file->elf, ".static_call_sites",
sizeof(struct static_call_site), idx);
sec = elf_create_section_pair(file->elf, ".static_call_sites",
sizeof(*site), idx, idx * 2);
if (!sec)
return -1;
/* Allow modules to set the low bits of static_call_site::key */
/* Allow modules to modify the low bits of static_call_site::key */
sec->sh.sh_flags |= SHF_WRITE;
idx = 0;
list_for_each_entry(insn, &file->static_call_list, call_node) {
site = (struct static_call_site *)sec->data->d_buf + idx;
memset(site, 0, sizeof(struct static_call_site));
/* populate reloc for 'addr' */
if (elf_add_reloc_to_insn(file->elf, sec,
idx * sizeof(struct static_call_site),
R_X86_64_PC32,
insn->sec, insn->offset))
if (!elf_init_reloc_text_sym(file->elf, sec,
idx * sizeof(*site), idx * 2,
insn->sec, insn->offset))
return -1;
/* find key symbol */
@ -735,10 +730,10 @@ static int create_static_call_sections(struct objtool_file *file)
free(key_name);
/* populate reloc for 'key' */
if (elf_add_reloc(file->elf, sec,
idx * sizeof(struct static_call_site) + 4,
R_X86_64_PC32, key_sym,
is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
if (!elf_init_reloc_data_sym(file->elf, sec,
idx * sizeof(*site) + 4,
(idx * 2) + 1, key_sym,
is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
return -1;
idx++;
@ -766,26 +761,18 @@ static int create_retpoline_sites_sections(struct objtool_file *file)
if (!idx)
return 0;
sec = elf_create_section(file->elf, ".retpoline_sites",
sizeof(int), idx);
if (!sec) {
WARN("elf_create_section: .retpoline_sites");
sec = elf_create_section_pair(file->elf, ".retpoline_sites",
sizeof(int), idx, idx);
if (!sec)
return -1;
}
idx = 0;
list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
int *site = (int *)sec->data->d_buf + idx;
*site = 0;
if (elf_add_reloc_to_insn(file->elf, sec,
idx * sizeof(int),
R_X86_64_PC32,
insn->sec, insn->offset)) {
WARN("elf_add_reloc_to_insn: .retpoline_sites");
if (!elf_init_reloc_text_sym(file->elf, sec,
idx * sizeof(int), idx,
insn->sec, insn->offset))
return -1;
}
idx++;
}
@ -812,26 +799,18 @@ static int create_return_sites_sections(struct objtool_file *file)
if (!idx)
return 0;
sec = elf_create_section(file->elf, ".return_sites",
sizeof(int), idx);
if (!sec) {
WARN("elf_create_section: .return_sites");
sec = elf_create_section_pair(file->elf, ".return_sites",
sizeof(int), idx, idx);
if (!sec)
return -1;
}
idx = 0;
list_for_each_entry(insn, &file->return_thunk_list, call_node) {
int *site = (int *)sec->data->d_buf + idx;
*site = 0;
if (elf_add_reloc_to_insn(file->elf, sec,
idx * sizeof(int),
R_X86_64_PC32,
insn->sec, insn->offset)) {
WARN("elf_add_reloc_to_insn: .return_sites");
if (!elf_init_reloc_text_sym(file->elf, sec,
idx * sizeof(int), idx,
insn->sec, insn->offset))
return -1;
}
idx++;
}
@ -864,12 +843,10 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
if (!idx)
return 0;
sec = elf_create_section(file->elf, ".ibt_endbr_seal",
sizeof(int), idx);
if (!sec) {
WARN("elf_create_section: .ibt_endbr_seal");
sec = elf_create_section_pair(file->elf, ".ibt_endbr_seal",
sizeof(int), idx, idx);
if (!sec)
return -1;
}
idx = 0;
list_for_each_entry(insn, &file->endbr_list, call_node) {
@ -884,13 +861,10 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
!strcmp(sym->name, "cleanup_module")))
WARN("%s(): not an indirect call target", sym->name);
if (elf_add_reloc_to_insn(file->elf, sec,
idx * sizeof(int),
R_X86_64_PC32,
insn->sec, insn->offset)) {
WARN("elf_add_reloc_to_insn: .ibt_endbr_seal");
if (!elf_init_reloc_text_sym(file->elf, sec,
idx * sizeof(int), idx,
insn->sec, insn->offset))
return -1;
}
idx++;
}
@ -902,7 +876,6 @@ static int create_cfi_sections(struct objtool_file *file)
{
struct section *sec;
struct symbol *sym;
unsigned int *loc;
int idx;
sec = find_section_by_name(file->elf, ".cfi_sites");
@ -923,7 +896,8 @@ static int create_cfi_sections(struct objtool_file *file)
idx++;
}
sec = elf_create_section(file->elf, ".cfi_sites", sizeof(unsigned int), idx);
sec = elf_create_section_pair(file->elf, ".cfi_sites",
sizeof(unsigned int), idx, idx);
if (!sec)
return -1;
@ -935,13 +909,9 @@ static int create_cfi_sections(struct objtool_file *file)
if (strncmp(sym->name, "__cfi_", 6))
continue;
loc = (unsigned int *)sec->data->d_buf + idx;
memset(loc, 0, sizeof(unsigned int));
if (elf_add_reloc_to_insn(file->elf, sec,
idx * sizeof(unsigned int),
R_X86_64_PC32,
sym->sec, sym->offset))
if (!elf_init_reloc_text_sym(file->elf, sec,
idx * sizeof(unsigned int), idx,
sym->sec, sym->offset))
return -1;
idx++;
@ -971,7 +941,8 @@ static int create_mcount_loc_sections(struct objtool_file *file)
list_for_each_entry(insn, &file->mcount_loc_list, call_node)
idx++;
sec = elf_create_section(file->elf, "__mcount_loc", addr_size, idx);
sec = elf_create_section_pair(file->elf, "__mcount_loc", addr_size,
idx, idx);
if (!sec)
return -1;
@ -979,17 +950,17 @@ static int create_mcount_loc_sections(struct objtool_file *file)
idx = 0;
list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
void *loc;
loc = sec->data->d_buf + idx;
memset(loc, 0, addr_size);
struct reloc *reloc;
if (elf_add_reloc_to_insn(file->elf, sec, idx,
addr_size == sizeof(u64) ? R_ABS64 : R_ABS32,
insn->sec, insn->offset))
reloc = elf_init_reloc_text_sym(file->elf, sec, idx * addr_size, idx,
insn->sec, insn->offset);
if (!reloc)
return -1;
idx += addr_size;
reloc->type = addr_size == 8 ? R_ABS64 : R_ABS32;
idx++;
}
return 0;
@ -999,7 +970,6 @@ static int create_direct_call_sections(struct objtool_file *file)
{
struct instruction *insn;
struct section *sec;
unsigned int *loc;
int idx;
sec = find_section_by_name(file->elf, ".call_sites");
@ -1016,20 +986,17 @@ static int create_direct_call_sections(struct objtool_file *file)
list_for_each_entry(insn, &file->call_list, call_node)
idx++;
sec = elf_create_section(file->elf, ".call_sites", sizeof(unsigned int), idx);
sec = elf_create_section_pair(file->elf, ".call_sites",
sizeof(unsigned int), idx, idx);
if (!sec)
return -1;
idx = 0;
list_for_each_entry(insn, &file->call_list, call_node) {
loc = (unsigned int *)sec->data->d_buf + idx;
memset(loc, 0, sizeof(unsigned int));
if (elf_add_reloc_to_insn(file->elf, sec,
idx * sizeof(unsigned int),
R_X86_64_PC32,
insn->sec, insn->offset))
if (!elf_init_reloc_text_sym(file->elf, sec,
idx * sizeof(unsigned int), idx,
insn->sec, insn->offset))
return -1;
idx++;

View File

@ -533,41 +533,6 @@ err:
return -1;
}
static struct section *elf_create_rela_section(struct elf *elf,
struct section *sec);
int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
unsigned int type, struct symbol *sym, s64 addend)
{
struct reloc *reloc;
if (!sec->rsec && !elf_create_rela_section(elf, sec))
return -1;
reloc = malloc(sizeof(*reloc));
if (!reloc) {
perror("malloc");
return -1;
}
memset(reloc, 0, sizeof(*reloc));
reloc->sec = sec->rsec;
reloc->offset = offset;
reloc->type = type;
reloc->sym = sym;
reloc->addend = addend;
list_add_tail(&reloc->sym_reloc_entry, &sym->reloc_list);
list_add_tail(&reloc->list, &sec->rsec->reloc_list);
elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
sec->rsec->sh.sh_size += sec->rsec->sh.sh_entsize;
mark_sec_changed(elf, sec->rsec, true);
return 0;
}
/*
* Ensure that any reloc section containing references to @sym is marked
* changed such that it will get re-generated in elf_rebuild_reloc_sections()
@ -841,13 +806,57 @@ elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size)
return sym;
}
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)
static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
unsigned int reloc_idx,
unsigned long offset, struct symbol *sym,
s64 addend, unsigned int type)
{
struct reloc *reloc;
if (reloc_idx >= rsec->sh.sh_size / elf_rela_size(elf)) {
WARN("%s: bad reloc_idx %u for %s with size 0x%lx",
__func__, reloc_idx, rsec->name, rsec->sh.sh_size);
return NULL;
}
reloc = malloc(sizeof(*reloc));
if (!reloc) {
perror("malloc");
return NULL;
}
memset(reloc, 0, sizeof(*reloc));
reloc->idx = reloc_idx;
reloc->sec = rsec;
reloc->offset = offset;
reloc->type = type;
reloc->sym = sym;
reloc->addend = addend;
list_add_tail(&reloc->sym_reloc_entry, &sym->reloc_list);
list_add_tail(&reloc->list, &rsec->reloc_list);
elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
mark_sec_changed(elf, rsec, true);
return reloc;
}
struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
unsigned long offset,
unsigned int reloc_idx,
struct section *insn_sec,
unsigned long insn_off)
{
struct symbol *sym = insn_sec->sym;
int addend = insn_off;
if (!(insn_sec->sh.sh_flags & SHF_EXECINSTR)) {
WARN("bad call to %s() for data symbol %s",
__func__, sym->name);
return NULL;
}
if (!sym) {
/*
* Due to how weak functions work, we must use section based
@ -857,12 +866,29 @@ int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
*/
sym = elf_create_section_symbol(elf, insn_sec);
if (!sym)
return -1;
return NULL;
insn_sec->sym = sym;
}
return elf_add_reloc(elf, sec, offset, type, sym, addend);
return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,
elf_text_rela_type(elf));
}
struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
unsigned long offset,
unsigned int reloc_idx,
struct symbol *sym,
s64 addend)
{
if (sym->sec && (sec->sh.sh_flags & SHF_EXECINSTR)) {
WARN("bad call to %s() for text symbol %s",
__func__, sym->name);
return NULL;
}
return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,
elf_data_rela_type(elf));
}
static int read_reloc(struct section *rsec, int i, struct reloc *reloc)
@ -1048,7 +1074,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
}
struct section *elf_create_section(struct elf *elf, const char *name,
size_t entsize, int nr)
size_t entsize, unsigned int nr)
{
struct section *sec, *shstrtab;
size_t size = entsize * nr;
@ -1129,7 +1155,8 @@ struct section *elf_create_section(struct elf *elf, const char *name,
}
static struct section *elf_create_rela_section(struct elf *elf,
struct section *sec)
struct section *sec,
unsigned int reloc_nr)
{
struct section *rsec;
char *rsec_name;
@ -1142,46 +1169,50 @@ static struct section *elf_create_rela_section(struct elf *elf,
strcpy(rsec_name, ".rela");
strcat(rsec_name, sec->name);
rsec = elf_create_section(elf, rsec_name, elf_rela_size(elf), 0);
rsec = elf_create_section(elf, rsec_name, elf_rela_size(elf), reloc_nr);
free(rsec_name);
if (!rsec)
return NULL;
sec->rsec = rsec;
rsec->base = sec;
rsec->data->d_type = ELF_T_RELA;
rsec->sh.sh_type = SHT_RELA;
rsec->sh.sh_addralign = elf_addr_size(elf);
rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
rsec->sh.sh_info = sec->idx;
rsec->sh.sh_flags = SHF_INFO_LINK;
sec->rsec = rsec;
rsec->base = sec;
return rsec;
}
struct section *elf_create_section_pair(struct elf *elf, const char *name,
size_t entsize, unsigned int nr,
unsigned int reloc_nr)
{
struct section *sec;
sec = elf_create_section(elf, name, entsize, nr);
if (!sec)
return NULL;
if (!elf_create_rela_section(elf, sec, reloc_nr))
return NULL;
return sec;
}
static int elf_rebuild_reloc_section(struct elf *elf, struct section *rsec)
{
bool rela = rsec->sh.sh_type == SHT_RELA;
struct reloc *reloc;
int idx = 0, ret;
void *buf;
/* Allocate a buffer for relocations */
buf = malloc(rsec->sh.sh_size);
if (!buf) {
perror("malloc");
return -1;
}
rsec->data->d_buf = buf;
rsec->data->d_size = rsec->sh.sh_size;
rsec->data->d_type = rela ? ELF_T_RELA : ELF_T_REL;
idx = 0;
list_for_each_entry(reloc, &rsec->reloc_list, list) {
reloc->rel.r_offset = reloc->offset;
reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
if (rela) {
if (rsec->sh.sh_type == SHT_RELA) {
reloc->rela.r_addend = reloc->addend;
ret = gelf_update_rela(rsec->data, idx, &reloc->rela);
} else {

View File

@ -111,15 +111,26 @@ struct elf {
};
struct elf *elf_open_read(const char *name, int flags);
struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr);
struct section *elf_create_section(struct elf *elf, const char *name,
size_t entsize, unsigned int nr);
struct section *elf_create_section_pair(struct elf *elf, const char *name,
size_t entsize, unsigned int nr,
unsigned int reloc_nr);
struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size);
int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
unsigned int type, struct symbol *sym, s64 addend);
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 reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
unsigned long offset,
unsigned int reloc_idx,
struct section *insn_sec,
unsigned long insn_off);
struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
unsigned long offset,
unsigned int reloc_idx,
struct symbol *sym,
s64 addend);
int elf_write_insn(struct elf *elf, struct section *sec,
unsigned long offset, unsigned int len,
@ -159,6 +170,16 @@ static inline size_t elf_rela_size(struct elf *elf)
return elf_addr_size(elf) == 4 ? sizeof(Elf32_Rela) : sizeof(Elf64_Rela);
}
static inline unsigned int elf_data_rela_type(struct elf *elf)
{
return elf_addr_size(elf) == 4 ? R_DATA32 : R_DATA64;
}
static inline unsigned int elf_text_rela_type(struct elf *elf)
{
return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
}
static inline bool is_reloc_sec(struct section *sec)
{
return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;

View File

@ -118,8 +118,8 @@ static int write_orc_entry(struct elf *elf, struct section *orc_sec,
orc->bp_offset = bswap_if_needed(elf, orc->bp_offset);
/* populate reloc for ip */
if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
insn_sec, insn_off))
if (!elf_init_reloc_text_sym(elf, ip_sec, idx * sizeof(int), idx,
insn_sec, insn_off))
return -1;
return 0;
@ -242,7 +242,7 @@ int orc_create(struct objtool_file *file)
if (!orc_sec)
return -1;
sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), nr);
sec = elf_create_section_pair(file->elf, ".orc_unwind_ip", sizeof(int), nr, nr);
if (!sec)
return -1;