Commit 468af56a authored by Julien Thierry's avatar Julien Thierry Committed by Josh Poimboeuf
Browse files

objtool: Support addition to set CFA base 



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: default avatarJulien Thierry <jthierry@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
parent fb084fde

tools/objtool/check.c

+11 −0
Original line number Diff line number Diff line
@@ -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 */