Commit 6342a20e authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

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: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent ff408273

tools/objtool/arch/powerpc/include/arch/elf.h

+7 −4
Original line number Diff line number Diff line 
/* 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_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 */

tools/objtool/arch/x86/include/arch/elf.h

+8 −3
Original line number Diff line number Diff line 
/* 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_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 */

tools/objtool/check.c

+48 −81
Original line number Diff line number Diff line
@@ -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 @@ static int add_dead_ends(struct objtool_file *file) 


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;
@@ -677,24 +676,20 @@ 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,

		if (!elf_init_reloc_text_sym(file->elf, sec,

					     idx * sizeof(*site), idx * 2,

					     insn->sec, insn->offset))

			return -1;
@@ -735,9 +730,9 @@ 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,

		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;
@@ -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;
@@ -935,12 +909,8 @@ 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,

		if (!elf_init_reloc_text_sym(file->elf, sec,

					     idx * sizeof(unsigned int), idx,

					     sym->sec, sym->offset))

			return -1;
@@ -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");
@@ -1016,19 +986,16 @@ 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,

		if (!elf_init_reloc_text_sym(file->elf, sec,

					     idx * sizeof(unsigned int), idx,

					     insn->sec, insn->offset))

			return -1;

tools/objtool/elf.c

+91 −60
Original line number Diff line number Diff line
@@ -533,41 +533,6 @@ static int read_symbols(struct elf *elf) 
	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;

}



static int elf_rebuild_reloc_section(struct elf *elf, struct section *rsec)

struct section *elf_create_section_pair(struct elf *elf, const char *name,

					size_t entsize, unsigned int nr,

					unsigned int reloc_nr)

{

	bool rela = rsec->sh.sh_type == SHT_RELA;

	struct reloc *reloc;

	int idx = 0, ret;

	void *buf;

	struct section *sec;



	/* Allocate a buffer for relocations */

	buf = malloc(rsec->sh.sh_size);

	if (!buf) {

		perror("malloc");

		return -1;

	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;

}



	rsec->data->d_buf = buf;

	rsec->data->d_size = rsec->sh.sh_size;

	rsec->data->d_type = rela ? ELF_T_RELA : ELF_T_REL;

static int elf_rebuild_reloc_section(struct elf *elf, struct section *rsec)

{

	struct reloc *reloc;

	int idx = 0, ret;



	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 {

tools/objtool/include/objtool/elf.h

+27 −6
Original line number Diff line number Diff line
@@ -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;