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Subject[PATCH 2/3] objtool: check: Support addition to set CFA base
Date
Instead of "mov SP, BP", a compiler could simply set BP
to SP + constant. Handle changing the CFA base in such cases.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
tools/objtool/check.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7db6761d28c2..f45991c2db41 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1898,6 +1898,19 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
break;
}

+ if (!cfi->drap && op->src.reg == CFI_SP &&
+ op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
+ check_reg_frame_pos(&regs[CFI_BP],
+ -cfa->offset + op->src.offset + CFA_SIZE,
+ CFA_BP_OFFSET)) {
+
+ /* lea disp(%rsp), %rbp */
+ cfa->base = CFI_BP;
+ cfa->offset -= op->src.offset;
+ cfi->bp_scratch = false;
+ break;
+ }
+
if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {

/* drap: lea disp(%rsp), %drap */
--
2.21.3
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