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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
This commit is contained in:
Alexandre Chartre 2020-04-07 09:31:35 +02:00 committed by Peter Zijlstra
parent 87cf61fe84
commit c721b3f80f
1 changed files with 8 additions and 0 deletions
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8
tools/objtool/check.c
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@ -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) if (cfi->stack_size != initial_func_cfi.cfa.offset + ret_offset)
return true; 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++) { for (i = 0; i < CFI_NUM_REGS; i++) {
if (cfi->regs[i].base != initial_func_cfi.regs[i].base || if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
cfi->regs[i].offset != initial_func_cfi.regs[i].offset) cfi->regs[i].offset != initial_func_cfi.regs[i].offset)