Commit 4c91be8e authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

objtool: Slice up elf_create_section_symbol() 



In order to facilitate creation of more symbol types, slice up
elf_create_section_symbol() to extract a generic helper that deals
with adding ELF symbols.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarYujie Liu <yujie.liu@intel.com>
Link: https://lkml.kernel.org/r/20221028194453.396634875@infradead.org
parent 5ebddd7c

tools/objtool/elf.c

+35 −21
Original line number Diff line number Diff line
@@ -717,11 +717,11 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab, 
}



static struct symbol *

elf_create_section_symbol(struct elf *elf, struct section *sec)

__elf_create_symbol(struct elf *elf, struct symbol *sym)

{

	struct section *symtab, *symtab_shndx;

	Elf32_Word first_non_local, new_idx;

	struct symbol *sym, *old;

	struct symbol *old;



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

	if (symtab) {
@@ -731,27 +731,16 @@ elf_create_section_symbol(struct elf *elf, struct section *sec) 
		return NULL;

	}



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

	if (!sym) {

		perror("malloc");

		return NULL;

	}

	new_idx = symtab->sh.sh_size / symtab->sh.sh_entsize;



	sym->name = sec->name;

	sym->sec = sec;



	// st_name 0

	sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);

	// st_other 0

	// st_value 0

	// st_size 0

	if (GELF_ST_BIND(sym->sym.st_info) != STB_LOCAL)

		goto non_local;



	/*

	 * Move the first global symbol, as per sh_info, into a new, higher

	 * symbol index. This fees up a spot for a new local symbol.

	 */

	first_non_local = symtab->sh.sh_info;

	new_idx = symtab->sh.sh_size / symtab->sh.sh_entsize;

	old = find_symbol_by_index(elf, first_non_local);

	if (old) {

		old->idx = new_idx;
@@ -769,17 +758,42 @@ elf_create_section_symbol(struct elf *elf, struct section *sec) 
		new_idx = first_non_local;

	}



	/*

	 * Either way, we will add a LOCAL symbol.

	 */

	symtab->sh.sh_info += 1;



non_local:

	sym->idx = new_idx;

	if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) {

		WARN("elf_update_symbol");

		return NULL;

	}



	/*

	 * Either way, we added a LOCAL symbol.

	 */

	symtab->sh.sh_info += 1;

	return sym;

}



static struct symbol *

elf_create_section_symbol(struct elf *elf, struct section *sec)

{

	struct symbol *sym = calloc(1, sizeof(*sym));



	if (!sym) {

		perror("malloc");

		return NULL;

	}



	sym->name = sec->name;

	sym->sec = sec;



	// st_name 0

	sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);

	// st_other 0

	// st_value 0

	// st_size 0



	sym = __elf_create_symbol(elf, sym);

	if (sym)

		elf_add_symbol(elf, sym);



	return sym;