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In-Reply-To: <20211203163424.GK16608@worktop.programming.kicks-ass.net>
From:   "H.J. Lu" <hjl.tools@gmail.com>
Date:   Fri, 3 Dec 2021 08:51:04 -0800
Message-ID: <CAMe9rOrVnb3oVRn5igjwimBbE6QH-v0tuHk-kjRz7osbJMQd1w@mail.gmail.com>
Subject: Re: [PATCH v8 05/14] x86: conditionally place regular ASM functions
 into separate sections
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Alexander Lobakin <alexandr.lobakin@intel.com>,
        linux-hardening@vger.kernel.org,
        "the arch/x86 maintainers" <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>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.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>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        live-patching@vger.kernel.org, llvm@lists.linux.dev
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On Fri, Dec 3, 2021 at 8:34 AM Peter Zijlstra <peterz@infradead.org> 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?

What exactly do you want assembler to do?

-- 
H.J.