Commit 1739c66e authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

objtool: Classify symbols 



In order to avoid calling str*cmp() on symbol names, over and over, do
them all once upfront and store the result.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Tested-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.658539311@infradead.org
parent b08cadbd

tools/objtool/check.c

+22 −12
Original line number Diff line number Diff line
@@ -1012,8 +1012,7 @@ static void add_call_dest(struct objtool_file *file, struct instruction *insn, 
	 * so they need a little help, NOP out any KCOV calls from noinstr

	 * text.

	 */

	if (insn->sec->noinstr &&

	    !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {

	if (insn->sec->noinstr && insn->call_dest->kcov) {

		if (reloc) {

			reloc->type = R_NONE;

			elf_write_reloc(file->elf, reloc);
@@ -1027,7 +1026,7 @@ static void add_call_dest(struct objtool_file *file, struct instruction *insn, 
		insn->type = sibling ? INSN_RETURN : INSN_NOP;

	}



	if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) {

	if (mcount && insn->call_dest->fentry) {

		if (sibling)

			WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
@@ -1077,7 +1076,7 @@ static int add_jump_destinations(struct objtool_file *file) 
		} else if (reloc->sym->type == STT_SECTION) {

			dest_sec = reloc->sym->sec;

			dest_off = arch_dest_reloc_offset(reloc->addend);

		} else if (arch_is_retpoline(reloc->sym)) {

		} else if (reloc->sym->retpoline_thunk) {

			/*

			 * Retpoline jumps are really dynamic jumps in

			 * disguise, so convert them accordingly.
@@ -1218,7 +1217,7 @@ static int add_call_destinations(struct objtool_file *file) 


			add_call_dest(file, insn, dest, false);



		} else if (arch_is_retpoline(reloc->sym)) {

		} else if (reloc->sym->retpoline_thunk) {

			/*

			 * Retpoline calls are really dynamic calls in

			 * disguise, so convert them accordingly.
@@ -1907,17 +1906,28 @@ static int read_intra_function_calls(struct objtool_file *file) 
	return 0;

}



static int read_static_call_tramps(struct objtool_file *file)

static int classify_symbols(struct objtool_file *file)

{

	struct section *sec;

	struct symbol *func;



	for_each_sec(file, sec) {

		list_for_each_entry(func, &sec->symbol_list, list) {

			if (func->bind == STB_GLOBAL &&

			    !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,

			if (func->bind != STB_GLOBAL)

				continue;



			if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,

				     strlen(STATIC_CALL_TRAMP_PREFIX_STR)))

				func->static_call_tramp = true;



			if (arch_is_retpoline(func))

				func->retpoline_thunk = true;



			if (!strcmp(func->name, "__fentry__"))

				func->fentry = true;



			if (!strncmp(func->name, "__sanitizer_cov_", 16))

				func->kcov = true;

		}

	}
@@ -1983,7 +1993,7 @@ static int decode_sections(struct objtool_file *file) 
	/*

	 * Must be before add_{jump_call}_destination.

	 */

	ret = read_static_call_tramps(file);

	ret = classify_symbols(file);

	if (ret)

		return ret;
@@ -2041,9 +2051,9 @@ static int decode_sections(struct objtool_file *file) 


static bool is_fentry_call(struct instruction *insn)

{

	if (insn->type == INSN_CALL && insn->call_dest &&

	    insn->call_dest->type == STT_NOTYPE &&

	    !strcmp(insn->call_dest->name, "__fentry__"))

	if (insn->type == INSN_CALL &&

	    insn->call_dest &&

	    insn->call_dest->fentry)

		return true;



	return false;

tools/objtool/include/objtool/elf.h

+5 −2
Original line number Diff line number Diff line
@@ -54,8 +54,11 @@ struct symbol { 
	unsigned long offset;

	unsigned int len;

	struct symbol *pfunc, *cfunc, *alias;

	bool uaccess_safe;

	bool static_call_tramp;

	u8 uaccess_safe      : 1;

	u8 static_call_tramp : 1;

	u8 retpoline_thunk   : 1;

	u8 fentry            : 1;

	u8 kcov              : 1;

	struct list_head pv_target;

};