Re: [PATCH] livepatch: set -f{function,data}-sections compiler option

From: Jan Beulich <jbeulich@suse.com>
To: Roger Pau Monne <roger.pau@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
	Bertrand Marquis <bertrand.marquis@arm.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH] livepatch: set -f{function,data}-sections compiler option
Date: Wed, 2 Mar 2022 17:13:00 +0100	[thread overview]
Message-ID: <c6188a3b-7ea1-48b0-c17e-9cd6ee645db8@suse.com> (raw)
In-Reply-To: <f67e599d-4dfc-c98e-75ee-8510237cd527@suse.com>

On 02.03.2022 15:41, Jan Beulich wrote:
> On 02.03.2022 14:44, Roger Pau Monne wrote:
>> --- a/xen/arch/x86/xen.lds.S
>> +++ b/xen/arch/x86/xen.lds.S
>> @@ -88,6 +88,9 @@ SECTIONS
>>  
>>         *(.text.cold)
>>         *(.text.unlikely)
>> +#ifdef CONFIG_LIVEPATCH
>> +       *(.text.*)
>> +#endif
> 
> This coming after the "cold" and "unlikely" special sections and
> ahead of .fixup isn't very nice. Also from looking at the linker
> scripts ld supplies I'm getting the impression that there could/
> would then also be e.g. .text.cold.* and .text.unlikely.* which
> you'd want to separate.

Thinking about it, with -ffunction-sections startup code cannot
reasonably be placed in .text.startup, or else there would be
confusion with code originating from a function named startup().
But of course .text.startup.* is similarly difficult to arrange
for not ending up in the output's main .text, so adding
.text.startup.* and .text.exit.* later in the script wouldn't
gain us anything.

Jan