Commit c721b3f8 authored Apr 07, 2020 by Alexandre Chartre Committed by Peter Zijlstra Apr 30, 2020

objtool: UNWIND_HINT_RET_OFFSET should not check registers



UNWIND_HINT_RET_OFFSET will adjust a modified stack. However if a
callee-saved register was pushed on the stack then the stack frame
will still appear modified. So stop checking registers when
UNWIND_HINT_RET_OFFSET is used.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200407073142.20659-3-alexandre.chartre@oracle.com

parent 87cf61fe

tools/objtool/check.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1507,6 +1507,14 @@ static bool has_modified_stack_frame(struct instruction *insn, struct insn_state
		if (cfi->stack_size != initial_func_cfi.cfa.offset + ret_offset)
		return true;

		/*
		* If there is a ret offset hint then don't check registers
		* because a callee-saved register might have been pushed on
		* the stack.
		*/
		if (ret_offset)
		return false;

		for (i = 0; i < CFI_NUM_REGS; i++) {
		if (cfi->regs[i].base != initial_func_cfi.regs[i].base \|\|
		cfi->regs[i].offset != initial_func_cfi.regs[i].offset)

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