On Fri, 16 Aug 2024 16:58:31 -0700
Namhyung Kim <namhyung@kernel.org> wrote:
> It missed to call check_allowed_ops() in __die_collect_vars_cb() so it
> can take variables with complex location expression incorrectly.
>
> For example, I found some variable has this expression.
>
> 015d8df8 ffffffff81aacfb3 (base address)
> 015d8e01 v000000000000004 v000000000000000 views at 015d8df2 for:
> ffffffff81aacfb3 ffffffff81aacfd2 (DW_OP_fbreg: -176; DW_OP_deref;
> DW_OP_plus_uconst: 332; DW_OP_deref_size: 4;
> DW_OP_lit1; DW_OP_shra; DW_OP_const1u: 64;
> DW_OP_minus; DW_OP_stack_value)
> 015d8e14 v000000000000000 v000000000000000 views at 015d8df4 for:
> ffffffff81aacfd2 ffffffff81aacfd7 (DW_OP_reg3 (rbx))
> 015d8e19 v000000000000000 v000000000000000 views at 015d8df6 for:
> ffffffff81aacfd7 ffffffff81aad020 (DW_OP_fbreg: -176; DW_OP_deref;
> DW_OP_plus_uconst: 332; DW_OP_deref_size: 4;
> DW_OP_lit1; DW_OP_shra; DW_OP_const1u: 64;
> DW_OP_minus; DW_OP_stack_value)
> 015d8e2c <End of list>
>
> It looks like '((int *)(-176(%rbp) + 332) >> 1) - 64' but the current
> code thought it's just -176(%rbp) and processed the variable incorrectly.
> It should reject such a complex expression if check_allowed_ops()
> doesn't like it. :)
Looks good to me. Hmm, I should reconsider to support this complex variable
on ftrace probe events...
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thanks,
>
> Fixes: 932dcc2c39ae ("perf dwarf-aux: Add die_collect_vars()")
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> tools/perf/util/dwarf-aux.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 5e080d7e22c2..beb632153a74 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -1598,6 +1598,9 @@ static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg)
> if (dwarf_getlocations(&attr, 0, &base, &start, &end, &ops, &nops) <= 0)
> return DIE_FIND_CB_SIBLING;
>
> + if (!check_allowed_ops(ops, nops))
> + return DIE_FIND_CB_SIBLING;
> +
> if (die_get_real_type(die_mem, &type_die) == NULL)
> return DIE_FIND_CB_SIBLING;
>
> --
> 2.46.0.184.g6999bdac58-goog
>
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>