linux-kernel - Re: [PATCH 2/2] powerpc/xmon: use KSYM_NAME

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Message-ID: <CANiq72nf-MC36hHzv0ZpR+qUyaf3mhF+rfqpMcVbw0AheuRBpA@mail.gmail.com>
Date:   Thu, 1 Jun 2023 12:27:30 +0200
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Maninder Singh <maninder1.s@...sung.com>, bcain@...cinc.com,
        npiggin@...il.com, christophe.leroy@...roup.eu,
        keescook@...omium.org, nathanl@...ux.ibm.com, ustavoars@...nel.org,
        alex.gaynor@...il.com, gary@...yguo.net, ojeda@...nel.org,
        pmladek@...e.com, wedsonaf@...gle.com,
        linux-hexagon@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Onkarnath <onkarnath.1@...sung.com>
Subject: Re: [PATCH 2/2] powerpc/xmon: use KSYM_NAME_LEN in array size

On Thu, Jun 1, 2023 at 4:02 AM Michael Ellerman <mpe@...erman.id.au> wrote:
>
> > Side-note: in `get_function_bounds()`, I see `kallsyms_lookup()` being
> > used, but the name seems discarded? Can
> > `kallsyms_lookup_size_offset()` be used instead, thus avoiding the
> > usage of the buffer there to begin with?
>
> A few lines below it uses the modname, and AFAICS there's no (easy) way
> to lookup the modname without also looking up the name.

Hmm... I think you are looking at the `xmon_print_symbol()` one? I was
referring to the `get_function_bounds()` one, where the `modname`
parameter is `NULL` (and the `name` contents are not used, only
whether it was found or not).

> > Side-note 2: in `scanhex()`, I see a loop `i<63` using `tmpstr` which
> > then is used to do a `kallsyms_lookup_name()`, so I guess symbols
> > larger than 64 couldn't be found. I have no idea about what are the
> > external constraints here, but perhaps it is possible to increase the
> > `line` buffer etc. to then allow for bigger symbols to be found.
>
> Yeah that looks wrong. I don't see any symbols that long in current
> kernels, but we should fix it.
>
> Thanks for looking.

My pleasure!

Cheers,
Miguel