Commit 243e9638 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool: Generalize elf_create_section() 



In preparation for the objtool klp diff subcommand, broaden the
elf_create_section() interface to give callers more control and reduce
duplication of some subtle setup logic.

While at it, make elf_create_rela_section() global so sections can be
created by the upcoming klp diff code.

Acked-by: default avatarPetr Mladek <pmladek@suse.com>
Tested-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent dd2c29aa

tools/objtool/elf.c

+64 −50
Original line number Diff line number Diff line
@@ -1138,35 +1138,39 @@ static int elf_add_string(struct elf *elf, struct section *strtab, const char *s 
}



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

				   size_t entsize, unsigned int nr)

				   size_t size, size_t entsize,

				   unsigned int type, unsigned int align,

				   unsigned int flags)

{

	struct section *sec, *shstrtab;

	size_t size = entsize * nr;

	Elf_Scn *s;



	sec = malloc(sizeof(*sec));

	if (name && find_section_by_name(elf, name)) {

		ERROR("section '%s' already exists", name);

		return NULL;

	}



	sec = calloc(1, sizeof(*sec));

	if (!sec) {

		ERROR_GLIBC("malloc");

		ERROR_GLIBC("calloc");

		return NULL;

	}

	memset(sec, 0, sizeof(*sec));



	INIT_LIST_HEAD(&sec->symbol_list);



	/* don't actually create the section, just the data structures */

	if (type == SHT_NULL)

		goto add;



	s = elf_newscn(elf->elf);

	if (!s) {

		ERROR_ELF("elf_newscn");

		return NULL;

	}



	sec->name = strdup(name);

	if (!sec->name) {

		ERROR_GLIBC("strdup");

		return NULL;

	}



	sec->idx = elf_ndxscn(s);



	if (size) {

		sec->data = elf_newdata(s);

		if (!sec->data) {

			ERROR_ELF("elf_newdata");
@@ -1176,13 +1180,11 @@ struct section *elf_create_section(struct elf *elf, const char *name, 
		sec->data->d_size = size;

		sec->data->d_align = 1;



	if (size) {

		sec->data->d_buf = malloc(size);

		sec->data->d_buf = calloc(1, size);

		if (!sec->data->d_buf) {

			ERROR_GLIBC("malloc");

			ERROR_GLIBC("calloc");

			return NULL;

		}

		memset(sec->data->d_buf, 0, size);

	}



	if (!gelf_getshdr(s, &sec->sh)) {
@@ -1192,33 +1194,43 @@ struct section *elf_create_section(struct elf *elf, const char *name, 


	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;

	sec->sh.sh_type = type;

	sec->sh.sh_addralign = align;

	sec->sh.sh_flags = flags;



	if (name) {

		sec->name = strdup(name);

		if (!sec->name) {

			ERROR("strdup");

			return NULL;

		}



		/* Add section name to .shstrtab (or .strtab for Clang) */

		shstrtab = find_section_by_name(elf, ".shstrtab");

	if (!shstrtab)

		if (!shstrtab) {

			shstrtab = find_section_by_name(elf, ".strtab");

			if (!shstrtab) {

		ERROR("can't find .shstrtab or .strtab section");

				ERROR("can't find .shstrtab or .strtab");

				return NULL;

			}

		}

		sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);

		if (sec->sh.sh_name == -1)

			return NULL;



		elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));

	}



add:

	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));



	mark_sec_changed(elf, sec, true);



	return sec;

}



static struct section *elf_create_rela_section(struct elf *elf,

					       struct section *sec,

struct section *elf_create_rela_section(struct elf *elf, struct section *sec,

					unsigned int reloc_nr)

{

	struct section *rsec;
@@ -1232,23 +1244,24 @@ 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), reloc_nr);

	rsec = elf_create_section(elf, rsec_name, reloc_nr * elf_rela_size(elf),

				  elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),

				  SHF_INFO_LINK);

	free(rsec_name);

	if (!rsec)

		return NULL;



	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;



	if (reloc_nr) {

		rsec->data->d_type = ELF_T_RELA;

		rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));

		if (!rsec->relocs) {

			ERROR_GLIBC("calloc");

			return NULL;

		}

	}



	sec->rsec = rsec;

	rsec->base = sec;
@@ -1262,7 +1275,8 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name, 
{

	struct section *sec;



	sec = elf_create_section(elf, name, entsize, nr);

	sec = elf_create_section(elf, name, nr * entsize, entsize,

				 SHT_PROGBITS, 1, SHF_ALLOC);

	if (!sec)

		return NULL;

tools/objtool/include/objtool/elf.h

+6 −1
Original line number Diff line number Diff line
@@ -117,11 +117,16 @@ 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, unsigned int nr);

				   size_t size, size_t entsize,

				   unsigned int type, unsigned int align,

				   unsigned int flags);

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

					size_t entsize, unsigned int nr,

					unsigned int reloc_nr);



struct section *elf_create_rela_section(struct elf *elf, struct section *sec,

					unsigned int reloc_nr);



struct symbol *elf_create_symbol(struct elf *elf, const char *name,

				 struct section *sec, unsigned int bind,

				 unsigned int type, unsigned long offset,

tools/objtool/orc_gen.c

+5 −1
Original line number Diff line number Diff line
@@ -127,7 +127,11 @@ int orc_create(struct objtool_file *file) 
		return -1;

	}

	orc_sec = elf_create_section(file->elf, ".orc_unwind",

				     sizeof(struct orc_entry), nr);

				     nr * sizeof(struct orc_entry),

				     sizeof(struct orc_entry),

				     SHT_PROGBITS,

				     1,

				     SHF_ALLOC);

	if (!orc_sec)

		return -1;