linux-kernel - Re: [PATCH] vmlinux.lds: Fix TEXT_MAIN to include .text.start and friends

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Message-ID: <2fm4yxe6nr6khoyjmo7r7v4u4zxwygz3wch2vb5yolo2tqjsx7@s27lvvoe6x3j>
Date: Wed, 5 Nov 2025 22:55:19 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>, 
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] vmlinux.lds: Fix TEXT_MAIN to include .text.start and
 friends

On Tue, Nov 04, 2025 at 10:11:42PM -0800, Josh Poimboeuf wrote:
> Since commit 6568f14cb5ae ("vmlinux.lds: Exclude .text.startup and
> .text.exit from TEXT_MAIN"), the TEXT_MAIN macro uses a series of
> patterns to prevent the .text.startup[.*] and .text.exit[.*] sections
> from getting linked into vmlinux runtime .text.
> 
> That commit is a tad too aggressive: it also inadvertently filters out
> valid runtime text sections like .text.start and
> .text.start.constprop.0, which can be generated for a function named
> start() when -ffunction-sections is enabled.
> 
> As a result, those sections become orphans when building with
> CONFIG_LD_DEAD_CODE_DATA_ELIMINATION for arm:
> 
>   arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/usb/host/sl811-hcd.o' being placed in section `.text.start.constprop.0'
>   arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/media/dvb-frontends/drxk_hard.o' being placed in section `.text.start.constprop.0'
>   arm-linux-gnueabi-ld: warning: orphan section `.text.start' from `drivers/media/dvb-frontends/stv0910.o' being placed in section `.text.start'
>   arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/media/pci/ddbridge/ddbridge-sx8.o' being placed in section `.text.start.constprop.0'
> 
> Fix that by explicitly adding the partial "substring" sections (.text.s,
> .text.st, .text.sta, etc) and their cloned derivatives.
> 
> While this unfortunately means that TEXT_MAIN continues to grow, these
> changes are ultimately necessary for proper support of
> -ffunction-sections.
> 
> Fixes: 6568f14cb5ae ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202511040812.DFGedJiy-lkp@intel.com/
> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
> ---
> For tip/objtool/core.

Nack.

There are still some additional headaches that need fixing.

For example, .text.startup is ambiguous: it could be constructor code
(for .init.text) or it could be a function named startup() which was
compiled with -ffunction-sections.

And we also have to deal with .text.startup.constprop.0 and
.text.startup.isra.0.

So the unification isn't quite working out, I'll come back with a new
set of patches to fix all this up again.

-- 
Josh