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[PATCH] um: Use asm-generic/timex.h over the host architecture one

Thomas Weißschuh posted 1 patch 1 month, 1 week ago
There is a newer version of this series
arch/um/include/asm/timex.h | 8 ++++++++
1 file changed, 8 insertions(+)
[PATCH] um: Use asm-generic/timex.h over the host architecture one
Posted by Thomas Weißschuh 1 month, 1 week ago 
The removal of the architecture-specific asm/timex.h was meant to fall
back to asm-generic/timex.h. However on UML, the host architecture
headers are earlier on the include path and therefore asm/timex.h from
the host architecture is used.
On x86 that header in turn requires the generation of cpufeaturemasks.h,
which is not set up for UML and the build fails.

In file included from ../arch/x86/include/asm/tsc.h:9,
                 from ../arch/x86/include/asm/timex.h:6,
                 from ../include/linux/timex.h:67,
                 from ../include/linux/time32.h:13,
                 from ../include/linux/time.h:60,
                 from ../include/linux/jiffies.h:10,
                 from ../include/linux/ktime.h:25,
                 from ../include/linux/timer.h:6,
                 from ../include/linux/uprobes.h:18,
                 from ../include/linux/mm_types.h:16,
                 from ../include/linux/mmzone.h:22,
                 from ../include/linux/gfp.h:7,
                 from ../include/linux/slab.h:17,
                 from ../include/linux/crypto.h:18,
                 from ../arch/um/kernel/asm-offsets.c:6:
arch/x86/include/asm/tsc.h: In function ‘get_cycles’:
arch/um/include/asm/cpufeature.h:52:39: error: implicit declaration of function ‘DISABLED_MASK_BIT_SET’ [-Wimplicit-function-declaration]
   52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
      |                                       ^~~~~~~~~~~~~~~~~~~~~
arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
   79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
      |              ^~~~~~~~~~~~~~~~~~~
arch/um/include/asm/cpufeature.h:115:17: error: implicit declaration of function ‘_static_cpu_has’ [-Wimplicit-function-declaration]
  115 |                 _static_cpu_has(bit)                            \
      |                 ^~~~~~~~~~~~~~~
arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro ‘_static_cpu_has’
   52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
      |                                                                        ^~~~~~~~~~~~~~~
arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
   79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
      |              ^~~~~~~~~~~~~~~~~~~
arch/um/include/asm/cpufeature.h:115:17: note: ‘_static_cpu_has’ is a function-like macro and might be used incorrectly
arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro ‘_static_cpu_has’
   52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
      |                                                                        ^~~~~~~~~~~~~~~
arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
   79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
      |              ^~~~~~~~~~~~~~~~~~~

The x86-specific timex.h also doesn't make sense on UML in general.

Reintroduce the UML-specific asm/timex.h and add a comment to document
its necessity.

Fixes: 3ed403bbc967 ("treewide: Remove CLOCK_TICK_RATE")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/um/include/asm/timex.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/um/include/asm/timex.h b/arch/um/include/asm/timex.h
new file mode 100644
index 000000000000..dfb4f460fb87
--- /dev/null
+++ b/arch/um/include/asm/timex.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_TIMEX_H
+#define __UM_TIMEX_H
+
+/* Do not fall back to the host architecture header. */
+#include <asm-generic/timex.h>
+
+#endif

---
base-commit: bd5f485f3f026225b86573e559af0b7254ef4184
change-id: 20260819-uml-timex-fix-fccb27f9ca51

Best regards,
--  
Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Re: [PATCH] um: Use asm-generic/timex.h over the host architecture one
Posted by SJ Park 4 weeks, 1 day ago 
On Wed, 19 Aug 2026 09:24:21 +0200 Thomas Weißschuh <thomas.weissschuh@linutronix.de> wrote:

> The removal of the architecture-specific asm/timex.h was meant to fall
> back to asm-generic/timex.h. However on UML, the host architecture
> headers are earlier on the include path and therefore asm/timex.h from
> the host architecture is used.
> On x86 that header in turn requires the generation of cpufeaturemasks.h,
> which is not set up for UML and the build fails.
> 
> In file included from ../arch/x86/include/asm/tsc.h:9,
>                  from ../arch/x86/include/asm/timex.h:6,
>                  from ../include/linux/timex.h:67,
>                  from ../include/linux/time32.h:13,
>                  from ../include/linux/time.h:60,
>                  from ../include/linux/jiffies.h:10,
>                  from ../include/linux/ktime.h:25,
>                  from ../include/linux/timer.h:6,
>                  from ../include/linux/uprobes.h:18,
>                  from ../include/linux/mm_types.h:16,
>                  from ../include/linux/mmzone.h:22,
>                  from ../include/linux/gfp.h:7,
>                  from ../include/linux/slab.h:17,
>                  from ../include/linux/crypto.h:18,
>                  from ../arch/um/kernel/asm-offsets.c:6:
> arch/x86/include/asm/tsc.h: In function ‘get_cycles’:
> arch/um/include/asm/cpufeature.h:52:39: error: implicit declaration of function ‘DISABLED_MASK_BIT_SET’ [-Wimplicit-function-declaration]
>    52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
>       |                                       ^~~~~~~~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
>    79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
>       |              ^~~~~~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:115:17: error: implicit declaration of function ‘_static_cpu_has’ [-Wimplicit-function-declaration]
>   115 |                 _static_cpu_has(bit)                            \
>       |                 ^~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro ‘_static_cpu_has’
>    52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
>       |                                                                        ^~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
>    79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
>       |              ^~~~~~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:115:17: note: ‘_static_cpu_has’ is a function-like macro and might be used incorrectly
> arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro ‘_static_cpu_has’
>    52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
>       |                                                                        ^~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
>    79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
>       |              ^~~~~~~~~~~~~~~~~~~
> 
> The x86-specific timex.h also doesn't make sense on UML in general.
> 
> Reintroduce the UML-specific asm/timex.h and add a comment to document
> its necessity.

I got the same issue, and confirmed this patch fixes it on my setup.  Thank you
for sharing this patch.

> 
> Fixes: 3ed403bbc967 ("treewide: Remove CLOCK_TICK_RATE")
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>

Tested-by: SJ Park <sj@kernel.org>


Thanks,
SJ

[...]
Re: [PATCH] um: Use asm-generic/timex.h over the host architecture one
Posted by David Gow 1 month, 1 week ago 
Le 19/08/2026 à 3:24 PM, Thomas Weißschuh a écrit :
> The removal of the architecture-specific asm/timex.h was meant to fall
> back to asm-generic/timex.h. However on UML, the host architecture
> headers are earlier on the include path and therefore asm/timex.h from
> the host architecture is used.
> On x86 that header in turn requires the generation of cpufeaturemasks.h,
> which is not set up for UML and the build fails.
> 
> In file included from ../arch/x86/include/asm/tsc.h:9,
>                  from ../arch/x86/include/asm/timex.h:6,
>                  from ../include/linux/timex.h:67,
>                  from ../include/linux/time32.h:13,
>                  from ../include/linux/time.h:60,
>                  from ../include/linux/jiffies.h:10,
>                  from ../include/linux/ktime.h:25,
>                  from ../include/linux/timer.h:6,
>                  from ../include/linux/uprobes.h:18,
>                  from ../include/linux/mm_types.h:16,
>                  from ../include/linux/mmzone.h:22,
>                  from ../include/linux/gfp.h:7,
>                  from ../include/linux/slab.h:17,
>                  from ../include/linux/crypto.h:18,
>                  from ../arch/um/kernel/asm-offsets.c:6:
> arch/x86/include/asm/tsc.h: In function ‘get_cycles’:
> arch/um/include/asm/cpufeature.h:52:39: error: implicit declaration of function ‘DISABLED_MASK_BIT_SET’ [-Wimplicit-function-declaration]
>    52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
>       |                                       ^~~~~~~~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
>    79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
>       |              ^~~~~~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:115:17: error: implicit declaration of function ‘_static_cpu_has’ [-Wimplicit-function-declaration]
>   115 |                 _static_cpu_has(bit)                            \
>       |                 ^~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro ‘_static_cpu_has’
>    52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
>       |                                                                        ^~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
>    79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
>       |              ^~~~~~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:115:17: note: ‘_static_cpu_has’ is a function-like macro and might be used incorrectly
> arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro ‘_static_cpu_has’
>    52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
>       |                                                                        ^~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
>    79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
>       |              ^~~~~~~~~~~~~~~~~~~
> 
> The x86-specific timex.h also doesn't make sense on UML in general.
> 
> Reintroduce the UML-specific asm/timex.h and add a comment to document
> its necessity.
> 
> Fixes: 3ed403bbc967 ("treewide: Remove CLOCK_TICK_RATE")
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---

Thanks: I just hit this, and came up with the identical fix. Can confirm
it works again across both 32- and 64-bit UML.

Reviewed-by: David Gow <david@davidgow.net>

Cheers,
-- David

>  arch/um/include/asm/timex.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/um/include/asm/timex.h b/arch/um/include/asm/timex.h
> new file mode 100644
> index 000000000000..dfb4f460fb87
> --- /dev/null
> +++ b/arch/um/include/asm/timex.h
> @@ -0,0 +1,8 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __UM_TIMEX_H
> +#define __UM_TIMEX_H
> +
> +/* Do not fall back to the host architecture header. */
> +#include <asm-generic/timex.h>
> +
> +#endif
> 
> ---
> base-commit: bd5f485f3f026225b86573e559af0b7254ef4184
> change-id: 20260819-uml-timex-fix-fccb27f9ca51
> 
> Best regards,
> --  
> Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> 
>
[tip: timers/urgent] um: Use asm-generic/timex.h over the host architecture one
Posted by tip-bot2 for Thomas Weißschuh 1 month ago 
The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     64f74d8f728877858372c52067e5c0c091f8db24
Gitweb:        https://git.kernel.org/tip/64f74d8f728877858372c52067e5c0c091f8db24
Author:        Thomas Weißschuh <thomas.weissschuh@linutronix.de>
AuthorDate:    Wed, 19 Aug 2026 09:24:21 +02:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 24 Aug 2026 17:10:35 -07:00

um: Use asm-generic/timex.h over the host architecture one

The removal of the architecture-specific asm/timex.h was meant to fall back to
asm-generic/timex.h. However on UML, the host architecture headers are earlier
on the include path and therefore asm/timex.h from the host architecture is
used.

On x86 that header in turn requires the generation of cpufeaturemasks.h, which
is not set up for UML and the build fails.

  In file included from ../arch/x86/include/asm/tsc.h:9,
                   from ../arch/x86/include/asm/timex.h:6,
                   from ../include/linux/timex.h:67,
                   from ../include/linux/time32.h:13,
                   from ../include/linux/time.h:60,
                   from ../include/linux/jiffies.h:10,
                   from ../include/linux/ktime.h:25,
                   from ../include/linux/timer.h:6,
                   from ../include/linux/uprobes.h:18,
                   from ../include/linux/mm_types.h:16,
                   from ../include/linux/mmzone.h:22,
                   from ../include/linux/gfp.h:7,
                   from ../include/linux/slab.h:17,
                   from ../include/linux/crypto.h:18,
                   from ../arch/um/kernel/asm-offsets.c:6:
  arch/x86/include/asm/tsc.h: In function ‘get_cycles’:
  arch/um/include/asm/cpufeature.h:52:39: error: implicit declaration of function ‘DISABLED_MASK_BIT_SET’ [-Wimplicit-function-declaration]
     52 |         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit))
        |                                       ^~~~~~~~~~~~~~~~~~~~~
  arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’
     79 |         if (!cpu_feature_enabled(X86_FEATURE_TSC))
        |              ^~~~~~~~~~~~~~~~~~~
  arch/um/include/asm/cpufeature.h:115:17: error: implicit declaration of function ‘_static_cpu_has’ [-Wimplicit-function-declaration]
    115 |                 _static_cpu_has(bit)                            \
        |                 ^~~~~~~~~~~~~~~
  ...

The x86-specific timex.h also doesn't make sense on UML in general.

Reintroduce the UML-specific asm/timex.h and add a comment to document
its necessity.

  [ bp: Improve that comment to actually state why stuff is there. ]

Fixes: 3ed403bbc967 ("treewide: Remove CLOCK_TICK_RATE")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: David Gow <david@davidgow.net>
Link: https://patch.msgid.link/20260819-uml-timex-fix-v1-1-f690b514fc9f@linutronix.de
---
 arch/um/include/asm/timex.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 arch/um/include/asm/timex.h

diff --git a/arch/um/include/asm/timex.h b/arch/um/include/asm/timex.h
new file mode 100644
index 0000000..39e392e
--- /dev/null
+++ b/arch/um/include/asm/timex.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_TIMEX_H
+#define __UM_TIMEX_H
+
+/*
+ * Do not fall back to the host architecture header because latter likely
+ * includes facilities like cpu_feature_enabled() which are present only
+ * there. That would result in build breakages and/or efforts to "emulate"
+ * those facilities in UML.
+ */
+#include <asm-generic/timex.h>
+
+#endif

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