linux-kernel - Re: [PATCH v7 3/8] kbuild: keep .modinfo section in vmlinux.unstripped

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Message-ID: <aMeqgPVfJcjBLhl8@levanger>
Date: Mon, 15 Sep 2025 07:56:16 +0200
From: Nicolas Schier <nsc@...nel.org>
To: Alexey Gladkov <legion@...nel.org>
Cc: Nathan Chancellor <nathan@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Daniel Gomez <da.gomez@...sung.com>, linux-kernel@...r.kernel.org,
	linux-modules@...r.kernel.org, linux-kbuild@...r.kernel.org,
	Masahiro Yamada <masahiroy@...nel.org>
Subject: Re: [PATCH v7 3/8] kbuild: keep .modinfo section in
 vmlinux.unstripped

On Mon, Aug 18, 2025 at 06:54:57PM +0200, Alexey Gladkov wrote:
> From: Masahiro Yamada <masahiroy@...nel.org>
> 
> Keep the .modinfo section during linking, but strip it from the final
> vmlinux.
> 
> Adjust scripts/mksysmap to exclude modinfo symbols from kallsyms.
> 
> This change will allow the next commit to extract the .modinfo section
> from the vmlinux.unstripped intermediate.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>  include/asm-generic/vmlinux.lds.h | 2 +-
>  scripts/Makefile.vmlinux          | 2 +-
>  scripts/mksysmap                  | 3 +++
>  3 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index ae2d2359b79e9..cfa63860dfd4c 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -831,6 +831,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
>  
>  /* Required sections not related to debugging. */
>  #define ELF_DETAILS							\
> +		.modinfo : { *(.modinfo) }				\
>  		.comment 0 : { *(.comment) }				\
>  		.symtab 0 : { *(.symtab) }				\
>  		.strtab 0 : { *(.strtab) }				\
> @@ -1044,7 +1045,6 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
>  	*(.discard.*)							\
>  	*(.export_symbol)						\
>  	*(.no_trim_symbol)						\
> -	*(.modinfo)							\
>  	/* ld.bfd warns about .gnu.version* even when not emitted */	\
>  	*(.gnu.version*)						\
>  
> diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> index 4f2d4c3fb7372..e2ceeb9e168d4 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -86,7 +86,7 @@ endif
>  # vmlinux
>  # ---------------------------------------------------------------------------
>  
> -remove-section-y                                   :=
> +remove-section-y                                   := .modinfo
>  remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*'
>  
>  quiet_cmd_strip_relocs = OBJCOPY $@
> diff --git a/scripts/mksysmap b/scripts/mksysmap
> index 3accbdb269ac7..a607a0059d119 100755
> --- a/scripts/mksysmap
> +++ b/scripts/mksysmap
> @@ -79,6 +79,9 @@
>  / _SDA_BASE_$/d
>  / _SDA2_BASE_$/d
>  
> +# MODULE_INFO()
> +/ __UNIQUE_ID_modinfo[0-9]*$/d
> +
>  # ---------------------------------------------------------------------------
>  # Ignored patterns
>  #  (symbols that contain the pattern are ignored)
> -- 
> 2.50.1
> 

Hi Alexey,

with this patch applied, I still get a warning from objcpy as Masahiro
and Stephen wrote [1,2]

  SORTTAB vmlinux.unstripped
+ sorttable vmlinux.unstripped
+ nm -S vmlinux.unstripped
+ ./scripts/sorttable -s .tmp_vmlinux.nm-sort vmlinux.unstripped
+ is_enabled CONFIG_KALLSYMS
+ grep -q ^CONFIG_KALLSYMS=y include/config/auto.conf
+ cmp -s System.map .tmp_vmlinux2.syms
+ echo vmlinux.unstripped: ../scripts/link-vmlinux.sh
# OBJCOPY vmlinux
  objcopy --remove-section=.modinfo vmlinux.unstripped vmlinux
objcopy: vmlinux.unstripped: warning: empty loadable segment detected at vaddr=0xffff8000807a0000, is this intentional?

(arm64, allnoconfig)

Kind regards,
Nicolas


[1]: https://lore.kernel.org/linux-kbuild/CAK7LNAR-gD2H6Kk-rZjo0R3weTHCGTm0a=u2tRH1WWW6Sx6=RQ@mail.gmail.com/
[2]: https://lore.kernel.org/lkml/20250730164047.7c4a731a@canb.auug.org.au/