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>,
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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
next prev parent 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
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