Commit 201ef5a9 authored by Julien Thierry's avatar Julien Thierry Committed by Josh Poimboeuf
Browse files

objtool: Make SP memory operation match PUSH/POP semantics 



Architectures without PUSH/POP instructions will always access the stack
though memory operations (SRC/DEST_INDIRECT). Make those operations have
the same effect on the CFA as PUSH/POP, with no stack pointer
modification.

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 468af56a

tools/objtool/check.c

+20 −0
Original line number Diff line number Diff line
@@ -2065,6 +2065,14 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi, 
			break;



		case OP_SRC_REG_INDIRECT:

			if (!cfi->drap && op->dest.reg == cfa->base &&

			    op->dest.reg == CFI_BP) {



				/* mov disp(%rsp), %rbp */

				cfa->base = CFI_SP;

				cfa->offset = cfi->stack_size;

			}



			if (cfi->drap && op->src.reg == CFI_BP &&

			    op->src.offset == cfi->drap_offset) {
@@ -2086,6 +2094,12 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi, 
				/* mov disp(%rbp), %reg */

				/* mov disp(%rsp), %reg */

				restore_reg(cfi, op->dest.reg);



			} else if (op->src.reg == CFI_SP &&

				   op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {



				/* mov disp(%rsp), %reg */

				restore_reg(cfi, op->dest.reg);

			}



			break;
@@ -2163,6 +2177,12 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi, 
			/* mov reg, disp(%rsp) */

			save_reg(cfi, op->src.reg, CFI_CFA,

				 op->dest.offset - cfi->cfa.offset);



		} else if (op->dest.reg == CFI_SP) {



			/* mov reg, disp(%rsp) */

			save_reg(cfi, op->src.reg, CFI_CFA,

				 op->dest.offset - cfi->stack_size);

		}



		break;