Re: [PATCH 1/1] arch:hexagon/powerpc: use KSYM_NAME_LEN in array size

[Miguel Ojeda]

On Mon, May 29, 2023 at 1:08 PM Maninder Singh <maninder1.s@xxxxxxxxxxx> wrote:
>
> I Will add co-developed-by` tag.
> because this change was identified while we were working on kallsyms some time back.
> https://lore.kernel.org/lkml/YonTOL4zC4CytVrn@xxxxxxxxxxxxx/t/
>
> this patch set is pending and we will start working on that again, so i thought better
> to send bugfix first.

Sounds good to me!

(Fixed Wedson's email address)

> Yes, I think second buffer was not related to kallsyms, so I have not touched that.

Kees: what is the current stance on `[static N]` parameters? Something like:

    const char *kallsyms_lookup(unsigned long addr,
                                unsigned long *symbolsize,
                                unsigned long *offset,
    -                           char **modname, char *namebuf);
    +                           char **modname, char namebuf[static
KSYM_NAME_LEN]);

makes the compiler complain about cases like these (even if trivial):

    arch/powerpc/xmon/xmon.c:1711:10: error: array argument is too small;
        contains 128 elements, callee requires at least 512
[-Werror,-Warray-bounds]
            name = kallsyms_lookup(pc, &size, &offset, NULL, tmpstr);
                 ^                                           ~~~~~~
    ./include/linux/kallsyms.h:86:29: note: callee declares array
parameter as static here
            char **modname, char namebuf[static KSYM_NAME_LEN]);
                                 ^      ~~~~~~~~~~~~~~~~~~~~~~

But I only see 2 files in the kernel using `[static N]` (from 2020 and
2021). Should something else be used instead (e.g. `__counted_by`),
even if constexpr-sized?.

Also, I went through the other callers to `kallsyms_lookup` to see
other issues -- one I am not sure about is `fetch_store_symstring` in
`kernel/trace/trace_probe_tmpl.h`. Steven/Masami: is that "with max
length" in the function docs enough? Is it 0xffff?

Thanks!

Cheers,
Miguel