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

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>,
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Subject: Re: [PATCH v9 05/15] x86: support ASM function sections
Date: Wed, 26 Jan 2022 15:49:52 +0100	[thread overview]
Message-ID: <20220126144952.851066-1-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <YerMYcin4woehiL9@zn.tnic>

From: Borislav Petkov <bp@alien8.de>
Date: Fri, 21 Jan 2022 16:08:17 +0100

> 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.

Yeah, sure. .fixup usage was removed in particular.
I'll queue v10 soon.

> 
> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.

Thanks for the reviews,
Al

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