Commit 4ea02938 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool: Mark .cold subfunctions 



Introduce a flag to identify .cold subfunctions so they can be detected
easier and faster.

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 25eac74b

tools/objtool/check.c

+6 −8
Original line number Diff line number Diff line
@@ -1575,7 +1575,9 @@ static int add_jump_destinations(struct objtool_file *file) 
		/*

		 * Cross-function jump.

		 */

		if (func && insn_func(jump_dest) && func != insn_func(jump_dest)) {



		if (func && insn_func(jump_dest) && !func->cold &&

		    insn_func(jump_dest)->cold) {



			/*

			 * For GCC 8+, create parent/child links for any cold
@@ -1592,12 +1594,9 @@ static int add_jump_destinations(struct objtool_file *file) 
			 * case where the parent function's only reference to a

			 * subfunction is through a jump table.

			 */

			if (!strstr(func->name, ".cold") &&

			    strstr(insn_func(jump_dest)->name, ".cold")) {

			func->cfunc = insn_func(jump_dest);

			insn_func(jump_dest)->pfunc = func;

		}

		}



		if (jump_is_sibling_call(file, insn, jump_dest)) {

			/*
@@ -4066,10 +4065,9 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
			 * If this hole jumps to a .cold function, mark it ignore too.

			 */

			if (insn->jump_dest && insn_func(insn->jump_dest) &&

			    strstr(insn_func(insn->jump_dest)->name, ".cold")) {

			    insn_func(insn->jump_dest)->cold)

				insn_func(insn->jump_dest)->ignore = true;

		}

		}



		return false;

	}

tools/objtool/elf.c

+10 −9
Original line number Diff line number Diff line
@@ -441,6 +441,10 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym) 
	list_add(&sym->list, entry);

	elf_hash_add(symbol, &sym->hash, sym->idx);

	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));



	if (is_func_sym(sym) && strstr(sym->name, ".cold"))

		sym->cold = 1;

	sym->pfunc = sym->cfunc = sym;

}



static int read_symbols(struct elf *elf)
@@ -527,18 +531,15 @@ static int read_symbols(struct elf *elf) 
		sec_for_each_sym(sec, sym) {

			char *pname;

			size_t pnamelen;

			if (!is_func_sym(sym))

				continue;



			if (sym->pfunc == NULL)

				sym->pfunc = sym;



			if (sym->cfunc == NULL)

				sym->cfunc = sym;

			if (!sym->cold)

				continue;



			coldstr = strstr(sym->name, ".cold");

			if (!coldstr)

				continue;

			if (!coldstr) {

				ERROR("%s(): cold subfunction without \".cold\"?", sym->name);

				return -1;

			}



			pnamelen = coldstr - sym->name;

			pname = strndup(sym->name, pnamelen);

tools/objtool/include/objtool/elf.h

+1 −0
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ struct symbol { 
	u8 frame_pointer     : 1;

	u8 ignore	     : 1;

	u8 nocfi             : 1;

	u8 cold		     : 1;

	struct list_head pv_target;

	struct reloc *relocs;

	struct section *group_sec;