From: Ard Biesheuvel <ardb@kernel.org>
To: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Sami Tolvanen <samitolvanen@google.com>,
Matt Helsley <mhelsley@vmware.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-mediatek@lists.infradead.org, yj.chiang@mediatek.com
Subject: Re: [PATCH] recordmcount: avoid using ABS symbol as reference
Date: Mon, 7 Jun 2021 08:37:27 +0200 [thread overview]
Message-ID: <CAMj1kXE3faN7nSSdoSU=ed+OPruefD_vJuhyRnsMuNiRygZZbg@mail.gmail.com> (raw)
In-Reply-To: <20210607023839.26387-1-mark-pk.tsai@mediatek.com>
On Mon, 7 Jun 2021 at 04:42, Mark-PK Tsai <mark-pk.tsai@mediatek.com> wrote:
>
> Avoid using ABS symbol, which won't be relocate, as reference.
>
> On arm64 platform, if there's shndx equals SHN_ABS(0xfff1).
>
> Section Headers:
> [Nr] Name Type Address Off Size ES Flg Lk Inf Al
> [65521] .text.n_tty_receive_buf PROGBITS 0000000000000000 3cdab520 000054 00 AX 0 0 4
> [65522] .rela.text.n_tty_receive_buf RELA 0000000000000000 3cdab578 000030 18 I 152076 65521 8
>
A RELA section's r_info field points to the section to which it
applies. This is why in the example above section #65522 points to
section #65521. This has nothing to do with the numerical value of
SHN_ABS.
> find_secsym_ndx, which use r_info in rela section to find the reference
> symbol, may take ABS symbol as base.
>
> Symbol table '.symtab' contains 453285 entries:
> Num: Value Size Type Bind Vis Ndx Name
> 6: 0000000000000002 0 NOTYPE LOCAL DEFAULT ABS section_count
>
> Which cause an invalid address in __mcount_loc.
>
Could you give a better account of the error you are trying to address?
Also, arm64 no longer defines a section_count symbol (since v5.11), so
please make sure that the diagnostics of the issue you are addressing
are accurate for mainline.
> Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
> ---
> scripts/recordmcount.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
> index f9b19524da11..9b69167fb7ff 100644
> --- a/scripts/recordmcount.h
> +++ b/scripts/recordmcount.h
> @@ -526,6 +526,10 @@ static int find_secsym_ndx(unsigned const txtndx,
> for (symp = sym0, t = nsym; t; --t, ++symp) {
> unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
>
> + /* avoid absolute symbols */
> + if (symp->st_shndx == SHN_ABS)
> + continue;
> +
> if (txtndx == get_symindex(symp, symtab, symtab_shndx)
> /* avoid STB_WEAK */
> && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
> --
> 2.18.0
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-07 6:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-07 2:38 [PATCH] recordmcount: avoid using ABS symbol as reference Mark-PK Tsai
2021-06-07 6:37 ` Ard Biesheuvel [this message]
2021-06-07 6:59 ` Mark-PK Tsai
2021-06-07 7:07 ` Ard Biesheuvel
2021-06-07 7:42 ` Mark-PK Tsai
2021-06-07 8:06 ` Mark-PK Tsai
2021-06-07 9:50 ` Ard Biesheuvel
2021-06-07 10:32 ` Mark-PK Tsai
2021-06-07 11:44 ` Peter Zijlstra
2021-06-07 13:18 ` Mark-PK Tsai
2021-06-07 13:44 ` Steven Rostedt
2021-06-07 17:31 ` Mark-PK Tsai
2021-06-07 15:40 ` Peter Zijlstra
2021-06-08 1:15 ` Mark-PK Tsai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMj1kXE3faN7nSSdoSU=ed+OPruefD_vJuhyRnsMuNiRygZZbg@mail.gmail.com' \
--to=ardb@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=mark-pk.tsai@mediatek.com \
--cc=matthias.bgg@gmail.com \
--cc=mhelsley@vmware.com \
--cc=rostedt@goodmis.org \
--cc=samitolvanen@google.com \
--cc=yj.chiang@mediatek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).