stable.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>,
	linux-hardening@vger.kernel.org, x86@kernel.org,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Kristen Carlson Accardi <kristen@linux.intel.com>,
	Kees Cook <keescook@chromium.org>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Ard Biesheuvel <ardb@kernel.org>, Tony Luck <tony.luck@intel.com>,
	Bruce Schlobohm <bruce.schlobohm@intel.com>,
	Jessica Yu <jeyu@kernel.org>, kernel test robot <lkp@intel.com>,
	Miroslav Benes <mbenes@suse.cz>,
	Evgenii Shatokhin <eshatokhin@virtuozzo.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Marios Pomonis <pomonis@google.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Nicolas Pitre <nico@fluxnic.net>,
	linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
	linux-arch@vger.kernel.org, live-patching@vger.kernel.org,
	llvm@lists.linux.dev, stable@vger.kernel.org
Subject: Re: [PATCH v9 01/15] modpost: fix removing numeric suffixes
Date: Mon, 27 Dec 2021 19:22:46 +0100	[thread overview]
Message-ID: <20211227182246.1447062-1-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <YcShenJgaOeOdbIj@zn.tnic>

From: Borislav Petkov <bp@alien8.de>
Date: Thu, 23 Dec 2021 17:19:06 +0100

> On Thu, Dec 23, 2021 at 01:21:55AM +0100, Alexander Lobakin wrote:
> > For now, that condition from remove_dot():
> > 
> > if (m && (s[n + m] == '.' || s[n + m] == 0))
> > 
> > which was designed to test if it's a dot or a \0 after the suffix
> > is never satisfied.
> > This is due to that s[n + m] always points to the last digit of a
> > numeric suffix, not on the symbol next to it:
> > 
> > param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0'
> > 
> > So it's off by one and was like that since 2014.
> 
> What's the relevance of this? Looking at
> 
>   7d02b490e93c ("Kbuild, lto: Drop .number postfixes in modpost")
> 
> what you're fixing here is something LTO-related. How do you trigger
> this?

It's just a couple lines below. I trigger this using `-z uniq-symbol`
which uses numeric suffixes for globals as well.

> 
> For a Cc:stable patch, I'm missing a lot of context.

It fixes a commit dated 2014, thus Cc:stable. Although the
remove_dot() might've been introduced for neverlanded GCC LTO, but
in fact numeric suffixes are used a lot by the toolchains in regular
builds as well. Just not for globals, that's why it's "well hidden".

> 
> > `-z uniq-symbol` linker flag which we are planning to use to
> 				     ^^
> 
> Who's "we"?

I thought it's a common saying in commit messages, isn't it?

> 
> > simplify livepatching brings numeric suffixes back, fix this.
> > Otherwise:
> > 
> > ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL
> > 
> > Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning")
> > Cc: stable@vger.kernel.org # 3.17+
> > Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> 
> ...
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

Thanks,
Al

  reply	other threads:[~2021-12-27 18:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20211223002209.1092165-1-alexandr.lobakin@intel.com>
2021-12-23  0:21 ` [PATCH v9 01/15] modpost: fix removing numeric suffixes Alexander Lobakin
2021-12-23 16:19   ` Borislav Petkov
2021-12-27 18:22     ` Alexander Lobakin [this message]
2021-12-27 21:26       ` Borislav Petkov
2021-12-28 17:03         ` Alexander Lobakin
2022-01-03 13:07   ` Miroslav Benes

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=20211227182246.1447062-1-alexandr.lobakin@intel.com \
    --to=alexandr.lobakin@intel.com \
    --cc=ardb@kernel.org \
    --cc=arnd@arndb.de \
    --cc=bp@alien8.de \
    --cc=bruce.schlobohm@intel.com \
    --cc=corbet@lwn.net \
    --cc=dave.hansen@linux.intel.com \
    --cc=davem@davemloft.net \
    --cc=eshatokhin@virtuozzo.com \
    --cc=herbert@gondor.apana.org.au \
    --cc=hjl.tools@gmail.com \
    --cc=hpa@zytor.com \
    --cc=jesse.brandeburg@intel.com \
    --cc=jeyu@kernel.org \
    --cc=jpoimboe@redhat.com \
    --cc=keescook@chromium.org \
    --cc=kristen@linux.intel.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-hardening@vger.kernel.org \
    --cc=linux-kbuild@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=live-patching@vger.kernel.org \
    --cc=lkp@intel.com \
    --cc=llvm@lists.linux.dev \
    --cc=luto@kernel.org \
    --cc=masahiroy@kernel.org \
    --cc=mbenes@suse.cz \
    --cc=mhiramat@kernel.org \
    --cc=michal.lkml@markovi.net \
    --cc=miklos@szeredi.hu \
    --cc=mingo@redhat.com \
    --cc=nathan@kernel.org \
    --cc=ndesaulniers@google.com \
    --cc=nico@fluxnic.net \
    --cc=peterz@infradead.org \
    --cc=pomonis@google.com \
    --cc=samitolvanen@google.com \
    --cc=stable@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    /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).