On Tue, Sep 15, 2020 at 09:12:04AM +0100, Julien Thierry wrote:
> 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: Julien Thierry <[email protected]>
> ---
> tools/objtool/check.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index f45991c2db41..7ff87fa3caec 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -2005,6 +2005,13 @@ 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) {
>
> @@ -2026,6 +2033,11 @@ 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 &&
An empty line above the else would help readability.
> + op->src.offset == regs[op->dest.reg].offset
> + cfi->stack_size) {
> +
> + /* mov disp(%rsp), %reg */
> + restore_reg(cfi, op->dest.reg);
> }
>
> break;
> @@ -2103,6 +2115,11 @@ 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) {
Same here.
> +
> + /* mov reg, disp(%rsp) */
> + save_reg(cfi, op->src.reg, CFI_CFA,
> + op->dest.offset - cfi->stack_size);
> }
>
> break;
> --
> 2.21.3
>
--
Josh
