diff mbox series

[06/11] s390/boot: vmlinux.lds.S: Handle '.rela' sections

Message ID 20240207-s390-lld-and-orphan-warn-v1-6-8a665b3346ab@kernel.org
State New
Headers
Series [01/11] s390: boot: Add support for CONFIG_LD_ORPHAN_WARN |

Commit Message

Nathan Chancellor Feb. 8, 2024, 12:14 a.m. UTC 
  When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are several warnings from
arch/s390/boot/head.o due to the unhandled presence of '.rela' sections:

  s390-linux-ld: warning: orphan section `.rela.iplt' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.head.text' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.got' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data.rel.ro' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.iplt' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.head.text' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.got' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
  s390-linux-ld: warning: orphan section `.rela.data.rel.ro' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'

These sections are unneeded for the decompressor and they are not
emitted in the binary currently. In a manner similar to other
architectures, coalesce the sections into '.rela.dyn' and ensure it is
zero sized, which is a safe/tested approach versus full discard.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 arch/s390/boot/vmlinux.lds.S | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Fangrui Song Feb. 13, 2024, 5:18 a.m. UTC | #1 
On Wed, Feb 7, 2024 at 4:15 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> When building with CONFIG_LD_ORPHAN_WARN after selecting
> CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are several warnings from
> arch/s390/boot/head.o due to the unhandled presence of '.rela' sections:
>
>   s390-linux-ld: warning: orphan section `.rela.iplt' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.head.text' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.got' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.data' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.data.rel.ro' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.iplt' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.head.text' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.got' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.data' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>   s390-linux-ld: warning: orphan section `.rela.data.rel.ro' from `arch/s390/boot/head.o' being placed in section `.rela.dyn'
>
> These sections are unneeded for the decompressor and they are not
> emitted in the binary currently. In a manner similar to other
> architectures, coalesce the sections into '.rela.dyn' and ensure it is
> zero sized, which is a safe/tested approach versus full discard.
>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>  arch/s390/boot/vmlinux.lds.S | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/s390/boot/vmlinux.lds.S b/arch/s390/boot/vmlinux.lds.S
> index 2f0bc05664ed..ff8c62d84f98 100644
> --- a/arch/s390/boot/vmlinux.lds.S
> +++ b/arch/s390/boot/vmlinux.lds.S
> @@ -137,6 +137,10 @@ SECTIONS
>                 *(.igot .igot.plt)
>         }
>         ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
> +       .rela.dyn : {
> +               *(.rela.*) *(.rela_*)
> +       }
> +       ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
>
>         /* Sections to be discarded */
>         /DISCARD/ : {
>
> --
> 2.43.0
>

Commit 5354e84598f264793265cc99b4be2a2295826c86 ("x86/build: Add
asserts for unwanted sections")
specifies `*(.rela.*) *(.rela_*)` but it's not clear why `.rela_*` is
included. We only need .rela.* (see also ld.bfd --verbose)

This patch LGTM with this changed.
Heiko Carstens Feb. 14, 2024, 12:17 p.m. UTC | #2 
On Mon, Feb 12, 2024 at 09:18:34PM -0800, Fangrui Song wrote:
> >         ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
> > +       .rela.dyn : {
> > +               *(.rela.*) *(.rela_*)
> > +       }
> > +       ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
..
> Commit 5354e84598f264793265cc99b4be2a2295826c86 ("x86/build: Add
> asserts for unwanted sections")
> specifies `*(.rela.*) *(.rela_*)` but it's not clear why `.rela_*` is
> included. We only need .rela.* (see also ld.bfd --verbose)
> 
> This patch LGTM with this changed.

I'll keep it as it is, just to be consistent with x86.
Fangrui Song Feb. 14, 2024, 9:32 p.m. UTC | #3 
On Wed, Feb 14, 2024 at 4:18 AM Heiko Carstens <hca@linux.ibm.com> wrote:
>
> On Mon, Feb 12, 2024 at 09:18:34PM -0800, Fangrui Song wrote:
> > >         ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
> > > +       .rela.dyn : {
> > > +               *(.rela.*) *(.rela_*)
> > > +       }
> > > +       ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
> ...
> > Commit 5354e84598f264793265cc99b4be2a2295826c86 ("x86/build: Add
> > asserts for unwanted sections")
> > specifies `*(.rela.*) *(.rela_*)` but it's not clear why `.rela_*` is
> > included. We only need .rela.* (see also ld.bfd --verbose)
> >
> > This patch LGTM with this changed.
>
> I'll keep it as it is, just to be consistent with x86.

Sent https://lore.kernel.org/all/20240214212929.3753766-1-maskray@google.com/
("[PATCH] x86/build: Simplify patterns for unwanted section")
to simplify the patterns in x86 vmlinux.lds.S:)
diff mbox series

Patch

diff --git a/arch/s390/boot/vmlinux.lds.S b/arch/s390/boot/vmlinux.lds.S
index 2f0bc05664ed..ff8c62d84f98 100644
--- a/arch/s390/boot/vmlinux.lds.S
+++ b/arch/s390/boot/vmlinux.lds.S
@@ -137,6 +137,10 @@  SECTIONS
 		*(.igot .igot.plt)
 	}
 	ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
+	.rela.dyn : {
+		*(.rela.*) *(.rela_*)
+	}
+	ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
 
 	/* Sections to be discarded */
 	/DISCARD/ : {