Commit 1c47c875 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Peter Zijlstra
Browse files

objtool: Include weak functions in global_noreturns check 



If a global function doesn't return, and its prototype has the
__noreturn attribute, its weak counterpart must also not return so that
it matches the prototype and meets call site expectations.

To properly follow the compiled control flow at the call sites, change
the global_noreturns check to include both global and weak functions.

On the other hand, if a weak function isn't in global_noreturns, assume
the prototype doesn't have __noreturn.  Even if the weak function
doesn't return, call sites treat it like a returnable function.

Fixes the following warning:

  kernel/sched/build_policy.o: warning: objtool: do_idle() falls through to next function play_idle_precise()

Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/ede3460d63f4a65d282c86f1175bd2662c2286ba.1681342859.git.jpoimboe@kernel.org
parent 27dea14c

tools/objtool/check.c

+4 −4
Original line number Diff line number Diff line
@@ -236,14 +236,14 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, 
	if (!func)

		return false;



	if (func->bind == STB_WEAK)

		return false;



	if (func->bind == STB_GLOBAL)

	if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)

		for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)

			if (!strcmp(func->name, global_noreturns[i]))

				return true;



	if (func->bind == STB_WEAK)

		return false;



	if (!func->len)

		return false;