Re: [PATCH v2 02/24] objtool: Introduce CFI hash

Miroslav Benes
2021-06-30T12:46:01Z

> @@ -2725,15 +2820,24 @@ static int validate_branch(struct objtoo
>
> if (insn->visited & visited)
> return 0;
> - }
> + } else
> + nr_visited++;

just a coding style

} else {
nr_visited++;
}

> @@ -3192,6 +3304,13 @@ int check(struct objtool_file *file)
> warnings += ret;
> }
>
> + if (stats) {
> + printf("nr_visited: %ld\n", nr_visited);

Could we make this nr_insns_visited?

> + printf("nr_cfi: %ld\n", nr_cfi);
> + printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
> + printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
> + }
> +
> +++ b/tools/objtool/orc_gen.c
> @@ -13,13 +13,19 @@
> #include <objtool/warn.h>
> #include <objtool/endianness.h>
>
> -static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi)
> +static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
> + struct instruction *insn)
> {
> - struct instruction *insn = container_of(cfi, struct instruction, cfi);
> struct cfi_reg *bp = &cfi->regs[CFI_BP];
>
> memset(orc, 0, sizeof(*orc));
>
> + if (!cfi) {
> + orc->end = 0;
> + orc->sp_reg = ORC_REG_UNDEFINED;
> + return 0;
> + }
> +

This looks strange. You access cfi a couple of lines earlier (bp cfi_reg
initialization).

Is it even possible to have cfi == NULL here? The second call site below
has a check and the first one should not happen (insn->cfip should be
always set if I am not missing something).

> orc->end = cfi->end;
>
> if (cfi->cfa.base == CFI_UNDEFINED) {
> @@ -162,7 +168,7 @@ int orc_create(struct objtool_file *file
> int i;
>
> if (!alt_group) {
> - if (init_orc_entry(&orc, &insn->cfi))
> + if (init_orc_entry(&orc, insn->cfip, insn))
> return -1;
> if (!memcmp(&prev_orc, &orc, sizeof(orc)))
> continue;
> @@ -186,7 +192,8 @@ int orc_create(struct objtool_file *file
> struct cfi_state *cfi = alt_group->cfi[i];
> if (!cfi)
> continue;
> - if (init_orc_entry(&orc, cfi))
> + /* errors are reported on the original insn */
> + if (init_orc_entry(&orc, cfi, insn))
> return -1;
> if (!memcmp(&prev_orc, &orc, sizeof(orc)))
> continue;

Anyway, this is a nice improvement.

Miroslav