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objtool: Support addition to set CFA base

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On arm64, the compiler can set the frame pointer either
with a move operation or with and add operation like:

    add (SP + constant), BP

For a simple move operation, the CFA base is changed from SP to BP.
Handle also changing the CFA base when the frame pointer is set with
an addition instruction.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
This commit is contained in:
Julien Thierry 2020-10-14 08:38:01 +01:00 committed by Josh Poimboeuf
parent fb084fde0c
commit 468af56a7b
1 changed files with 11 additions and 0 deletions
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11
tools/objtool/check.c
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@ -1960,6 +1960,17 @@ 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)) {
/* 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 */