linux-kernel - [PATCH] powerpc: Implement ARCH_HAS_CC_CAN

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Message-Id: <20251230-cc-can-link-powerpc-v1-1-82298df6e3bf@linutronix.de>
Date: Tue, 30 Dec 2025 08:06:10 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Madhavan Srinivasan <maddy@...ux.ibm.com>, 
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>, 
 "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH] powerpc: Implement ARCH_HAS_CC_CAN_LINK

The generic CC_CAN_LINK detection does not handle different byte orders.
This may lead to userprogs which are not actually runnable on the target
kernel.

Use architecture-specific logic supporting byte orders instead.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 arch/powerpc/Kconfig | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9537a61ebae0..6bb2f90e97ea 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -127,6 +127,7 @@ config PPC
 	select ARCH_DMA_DEFAULT_COHERENT	if !NOT_COHERENT_CACHE
 	select ARCH_ENABLE_MEMORY_HOTPLUG
 	select ARCH_ENABLE_MEMORY_HOTREMOVE
+	select ARCH_HAS_CC_CAN_LINK
 	select ARCH_HAS_COPY_MC			if PPC64
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL
@@ -1342,6 +1343,20 @@ endif
 config PPC_LIB_RHEAP
 	bool
 
+config ARCH_CC_CAN_LINK
+	bool
+	default $(cc_can_link_user,$(m64-flag) -mlittle-endian) if 64BIT && CPU_LITTLE_ENDIAN
+	default $(cc_can_link_user,$(m64-flag) -mbig-endian) if 64BIT && CPU_BIG_ENDIAN
+	default $(cc_can_link_user,$(m32-flag) -mlittle-endian) if CPU_LITTLE_ENDIAN
+	default $(cc_can_link_user,$(m32-flag) -mbig-endian) if CPU_BIG_ENDIAN
+
+config ARCH_USERFLAGS
+	string
+	default "$(m64-flag) -mlittle-endian" if 64BIT && CPU_LITTLE_ENDIAN
+	default "$(m64-flag) -mbig-endian" if 64BIT && CPU_BIG_ENDIAN
+	default "$(m32-flag) -mlittle-endian" if CPU_LITTLE_ENDIAN
+	default "$(m32-flag) -mbig-endian" if CPU_BIG_ENDIAN
+
 source "arch/powerpc/kvm/Kconfig"
 
 source "kernel/livepatch/Kconfig"

---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251222-cc-can-link-powerpc-5ddd2469fd5b

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