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Subject[PATCH V2 2/9] objtool: UNWIND_HINT_RET_OFFSET should not check registers
Date
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>
---
tools/objtool/check.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index bbee26de92ec..c7fcaddfaa8a 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1390,6 +1390,14 @@ static bool has_modified_stack_frame(struct instruction *insn,
if (state->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 (state->regs[i].base != initial_func_cfi.regs[i].base ||
state->regs[i].offset != initial_func_cfi.regs[i].offset)
--
2.18.2
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