Date:   Fri, 3 Dec 2021 14:46:39 -0500 (EST)
From:   Nicolas Pitre <nico@fluxnic.net>
To:     Peter Zijlstra <peterz@infradead.org>
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>,
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        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
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        llvm@lists.linux.dev, hjl.tools@gmail.com
Subject: Re: [PATCH v8 05/14] x86: conditionally place regular ASM functions
 into separate sections
In-Reply-To: <20211203163424.GK16608@worktop.programming.kicks-ass.net>
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References: <20211202223214.72888-1-alexandr.lobakin@intel.com> <20211202223214.72888-6-alexandr.lobakin@intel.com> <Yanm6tJ2obi1aKv6@hirez.programming.kicks-ass.net> <20211203141051.82467-1-alexandr.lobakin@intel.com>
 <20211203163424.GK16608@worktop.programming.kicks-ass.net>
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On Fri, 3 Dec 2021, Peter Zijlstra wrote:

> On Fri, Dec 03, 2021 at 03:10:51PM +0100, Alexander Lobakin wrote:
> > From: Peter Zijlstra <peterz@infradead.org>
> > Date: Fri, 3 Dec 2021 10:44:10 +0100
> > 
> > > On Thu, Dec 02, 2021 at 11:32:05PM +0100, Alexander Lobakin wrote:
> > > > Use the newly introduces macros to create unique separate sections
> > > > for (almost) every "regular" ASM function (i.e. for those which
> > > > aren't explicitly put into a specific one).
> > > > There should be no leftovers as input .text will be size-asserted
> > > > in the LD script generated for FG-KASLR.
> > > 
> > > *groan*...
> > > 
> > > Please, can't we do something like:
> > > 
> > > #define SYM_PUSH_SECTION(name)	\
> > > .if section == .text		\
> > > .push_section .text.##name	\
> > > .else				\
> > > .push_section .text		\
> > > .endif
> > > 
> > > #define SYM_POP_SECTION()	\
> > > .pop_section
> > > 
> > > and wrap that inside the existing SYM_FUNC_START*() SYM_FUNC_END()
> > > macros.
> > 
> > Ah I see. I asked about this in my previous mail and you replied
> > already (: Cool stuff, I'll use it, it simplifies things a lot.
> 
> Note, I've no idea if it works. GAS and me aren't really on speaking
> terms. It would be my luck for that to be totally impossible, hjl?

Surely this would do it:

http://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=451133cefa839104


Nicolas