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

From: Miguel Ojeda
Date: Mon May 29 2023 - 10:51:01 EST

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.
> 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

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
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?