[PATCH v2] ARM: Implement ARCH_HAS_CC_CAN_LINK

[PATCH v2] ARM: Implement ARCH_HAS_CC_CAN_LINK

[Thomas Weißschuh]

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@linutronix.de>
---
Changes in v2:
- Handle BE8 vs BE32 platforms
- Link to v1: https://lore.kernel.org/r/20260109-cc-can-link-arm-v1-1-b748e2aaa6a6@linutronix.de
---
 arch/arm/Kconfig | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index fa83c040ee2d..d5cb85d82dad 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -6,6 +6,7 @@ config ARM
 	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE if HAVE_KRETPROBES && FRAME_POINTER && !ARM_UNWIND
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_CACHE_LINE_SIZE if OF
+	select ARCH_HAS_CC_CAN_LINK
 	select ARCH_HAS_CPU_CACHE_ALIASING
 	select ARCH_HAS_CPU_FINALIZE_INIT if MMU
 	select ARCH_HAS_CURRENT_STACK_POINTER
@@ -1715,6 +1716,18 @@ config KERNEL_MODE_NEON
 
 endmenu
 
+config ARCH_CC_CAN_LINK
+	bool
+	default $(cc_can_link_user,-mlittle-endian) if CPU_LITTLE_ENDIAN
+	default $(cc_can_link_user,-mbig-endian -mbe8) if CPU_ENDIAN_BE8
+	default $(cc_can_link_user,-mbig-endian -mbe32) if CPU_ENDIAN_BE32
+
+config ARCH_USERFLAGS
+	string
+	default "-mlittle-endian" if CPU_LITTLE_ENDIAN
+	default "-mbig-endian -mbe8" if CPU_ENDIAN_BE8
+	default "-mbig-endian -mbe32" if CPU_ENDIAN_BE32
+
 menu "Power management options"
 
 source "kernel/power/Kconfig"

---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20260102-cc-can-link-arm-4eecfad2a0e4

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

Re: [PATCH v2] ARM: Implement ARCH_HAS_CC_CAN_LINK

[Russell King (Oracle)]

On Fri, Feb 06, 2026 at 02:02:38PM +0100, Thomas Weißschuh wrote:
> 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@linutronix.de>

Damn, I've recently merged your v1 patch. Can you send a follow-up
patch to my patch system please?

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH v2] ARM: Implement ARCH_HAS_CC_CAN_LINK

[Thomas Weißschuh]

On Fri, Feb 06, 2026 at 01:29:31PM +0000, Russell King (Oracle) wrote:
> On Fri, Feb 06, 2026 at 02:02:38PM +0100, Thomas Weißschuh wrote:
> > 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@linutronix.de>
> 
> Damn, I've recently merged your v1 patch. Can you send a follow-up
> patch to my patch system please?

Oh, sorry. That was a fast application.

Do you want an incremental patch on top or the full v2?


Thomas

Re: [PATCH v2] ARM: Implement ARCH_HAS_CC_CAN_LINK

[Russell King (Oracle)]

On Fri, Feb 06, 2026 at 02:32:42PM +0100, Thomas Weißschuh wrote:
> On Fri, Feb 06, 2026 at 01:29:31PM +0000, Russell King (Oracle) wrote:
> > On Fri, Feb 06, 2026 at 02:02:38PM +0100, Thomas Weißschuh wrote:
> > > 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@linutronix.de>
> > 
> > Damn, I've recently merged your v1 patch. Can you send a follow-up
> > patch to my patch system please?
> 
> Oh, sorry. That was a fast application.
> 
> Do you want an incremental patch on top or the full v2?

Incremental please.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!