Re: s390: s390x-linux-gnu-ld: Unexpected GOT/PLT entries detected!

[Heiko Carstens <hca@linux.ibm.com>]

On Fri, Feb 23, 2024 at 03:11:50PM +0530, Naresh Kamboju wrote:
> [ Please ignore this email if it is already reported ]
> 
> The s390 gcc-8 builds failed on Linux next tag next-20240215..next-20240223.
> First build failures noticed on tag next-20240215 for both gcc-13 and gcc-8.
> But from the next tag next-20240216 gcc-13 passed but gcc-8 failed.
> 
> s390:
>     - defconfig-fe40093d - gcc-8 - Failed
>     - tinyconfig - gcc-8 - Failed
>     - allnoconfig - gcc-8 - Failed
...
> Build log:
> ---------
> s390x-linux-gnu-ld: Unexpected GOT/PLT entries detected!
> make[3]: *** [/builds/linux/arch/s390/boot/Makefile:87:
> arch/s390/boot/vmlinux.syms] Error 1
> make[3]: Target 'arch/s390/boot/bzImage' not remade because of errors.
...
> Steps to reproduce:
>  $ tuxmake --runtime podman --target-arch s390 --toolchain gcc-8
> --kconfig tinyconfig
> 
> Links:
>  - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240223/testrun/22812529/suite/build/test/gcc-8-defconfig-fe40093d/details/
>  - https://storage.tuxsuite.com/public/linaro/lkft/builds/2cl8pys1B3Vc4oOB2yXcaYkfnKw/

Thanks should hopefully be fixed with the patch below, which should be
part of the next linux-next release.

https://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git/commit/?h=features&id=a795e5d2347def129734a7f247ac70339d50d8c2

From a795e5d2347def129734a7f247ac70339d50d8c2 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@linux.ibm.com>
Date: Sun, 25 Feb 2024 17:39:12 +0100
Subject: [PATCH] s390: vmlinux.lds.S: fix .got.plt assertion

Naresh reported this build error on linux-next:

s390x-linux-gnu-ld: Unexpected GOT/PLT entries detected!
make[3]: *** [/builds/linux/arch/s390/boot/Makefile:87:
arch/s390/boot/vmlinux.syms] Error 1
make[3]: Target 'arch/s390/boot/bzImage' not remade because of errors.

The reason for the build error is an incorrect/incomplete assertion which
checks the size of the .got.plt section. Similar to x86 the size is either
zero or 24 bytes (three entries).

See commit 262b5cae67a6 ("x86/boot/compressed: Move .got.plt entries out of
the .got section") for more details. The three reserved/additional entries
for s390 are described in chapter 3.2.2 of the s390x ABI [1] (thanks to
Andreas Krebbel for pointing this out!).

[1] https://github.com/IBM/s390x-abi/releases/download/v1.6.1/lzsabi_s390x.pdf

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYvWp8TY-fMEvc3UhoVtoR_eM5VsfHj3+n+kexcfJJ+Cvw@mail.gmail.com
Fixes: 30226853d6ec ("s390: vmlinux.lds.S: explicitly handle '.got' and '.plt' sections")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/boot/vmlinux.lds.S   | 11 ++++++++---
 arch/s390/kernel/vmlinux.lds.S | 11 ++++++++---
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/arch/s390/boot/vmlinux.lds.S b/arch/s390/boot/vmlinux.lds.S
index e3208893ba6b..3d7ea585ab99 100644
--- a/arch/s390/boot/vmlinux.lds.S
+++ b/arch/s390/boot/vmlinux.lds.S
@@ -144,13 +144,18 @@ SECTIONS
 	ELF_DETAILS
 
 	/*
-	 * Sections that should stay zero sized, which is safer to
-	 * explicitly check instead of blindly discarding.
+	 * Make sure that the .got.plt is either completely empty or it
+	 * contains only the three reserved double words.
 	 */
 	.got.plt : {
 		*(.got.plt)
 	}
-	ASSERT(SIZEOF(.got.plt) == 0, "Unexpected GOT/PLT entries detected!")
+	ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT entries detected!")
+
+	/*
+	 * Sections that should stay zero sized, which is safer to
+	 * explicitly check instead of blindly discarding.
+	 */
 	.plt : {
 		*(.plt) *(.plt.*) *(.iplt) *(.igot .igot.plt)
 	}
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 404883b1b023..9c59715d1745 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -266,13 +266,18 @@ SECTIONS
 	ELF_DETAILS
 
 	/*
-	 * Sections that should stay zero sized, which is safer to
-	 * explicitly check instead of blindly discarding.
+	 * Make sure that the .got.plt is either completely empty or it
+	 * contains only the three reserved double words.
 	 */
 	.got.plt : {
 		*(.got.plt)
 	}
-	ASSERT(SIZEOF(.got.plt) == 0, "Unexpected GOT/PLT entries detected!")
+	ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT entries detected!")
+
+	/*
+	 * Sections that should stay zero sized, which is safer to
+	 * explicitly check instead of blindly discarding.
+	 */
 	.plt : {
 		*(.plt) *(.plt.*) *(.iplt) *(.igot .igot.plt)
 	}
-- 
2.43.2