Re: [PATCH v9 05/15] x86: support ASM function sections

From: Borislav Petkov <bp@alien8.de>
To: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: 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
Subject: Re: [PATCH v9 05/15] x86: support ASM function sections
Date: Fri, 21 Jan 2022 16:08:17 +0100	[thread overview]
Message-ID: <YerMYcin4woehiL9@zn.tnic> (raw)
In-Reply-To: <20211223002209.1092165-6-alexandr.lobakin@intel.com>

On Thu, Dec 23, 2021 at 01:21:59AM +0100, Alexander Lobakin wrote:
> Address places which need special care and enable
> CONFIG_ARCH_SUPPORTS_ASM_FUNCTION_SECTIONS.
> 
> Notably:
>  - propagate --sectname-subst to aflags in x86/boot/Makefile and
>    x86/boot/compressed/Makefile as both override aflags;

s/aflags/KBUILD_AFLAGS/

Let's be more precise pls.

>  - symbols starting with a dot (like ".Lbad_gs") should be handled
>    manually with SYM_*_START_SECT(.Lbad_gs, bad_gs) as "two dots"
>    is a special (and CPP doesn't want to concatenate two dots in
>    general);
>  - some symbols explicitly need to reside in one section (like
>    kexec control code, hibernation page etc.);
>  - macros creating aliases for functions (like __memcpy() for
>    memcpy() etc.) should go after the main declaration (as
>    aliases should be declared in the same section and they
>    don't have SYM_PUSH_SECTION() inside);
>  - things like ".org", ".align" should be manually pushed to
>    the same section the next symbol goes to;
>  - expand indirect_thunk and .fixup wildcards in vmlinux.lds.S

$ git grep -E "\.fixup" arch/x86/*.S
$

I guess I'll continue with your new version since a bunch of stuff
has changed in arch/x86/ in the meantime so that that set would need
refreshing.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette