linux-kernel - [PATCH] s390: Implement ARCH_HAS_CC_CAN

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Message-Id: <20251222-cc-can-link-s390-v1-1-0b2c4998c066@linutronix.de>
Date: Mon, 22 Dec 2025 09:28:17 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>, 
 Alexander Gordeev <agordeev@...ux.ibm.com>, 
 Christian Borntraeger <borntraeger@...ux.ibm.com>, 
 Sven Schnelle <svens@...ux.ibm.com>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH] s390: Implement ARCH_HAS_CC_CAN_LINK

The generic CC_CAN_LINK detection relies on -m32/-m64 compiler flags.
s390 toolchains use -m31 instead but that is not supported in the
kernel.

Make the logic easier to understand and allow the simplification of the
generic CC_CAN_LINK by using a tailored implementation.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 arch/s390/Kconfig | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0e5fad5f06ca..cd856318ffe5 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -85,6 +85,7 @@ config S390
 	select ARCH_ENABLE_MEMORY_HOTREMOVE
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
+	select ARCH_HAS_CC_CAN_LINK
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL
@@ -294,6 +295,14 @@ config PGTABLE_LEVELS
 
 source "kernel/livepatch/Kconfig"
 
+config ARCH_CC_CAN_LINK
+	bool
+	default $(cc_can_link_user,-m64)
+
+config ARCH_USERFLAGS
+	string
+	default "-m64"
+
 config ARCH_SUPPORTS_KEXEC
 	def_bool y
 

---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251222-cc-can-link-s390-223eca6ac085

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@...utronix.de>