Re: [RFC PATCH 9/9] arm64/debug: Mark debug exception helpers __always_inline

[Hongyan Xia <hongyan.xia@transsion.com>]

On 7/28/2026 3:22 AM, Nick Desaulniers wrote:
> On Mon, Jul 27, 2026 at 5:25 AM Hongyan Xia <hongyan.xia@transsion.com> wrote:
>>
>> From: Hongyan Xia <hongyan.xia@transsion.com>
>>
>> Static inline should be enough to actually inline functions for most
>> compilers, but my Clang-19 somehow thinks it's better to outline them.
>> These tiny helpers then live in normal .text sections instead of
>> .noinstr sections, violating noinstr.
>
> Anything special about your build or config?  For example, we've seen
> a recent influx of bugs around AutoFDO not inlining functions (despite
> constant propagating initdata constants into them) leading to modpost
> errors.

I doubt there's anything special. The compiler is Debian clang version
19.1.7 (3+b1) installed through apt install in vanilla x86_64 Debian
Trixie, compiled with 'make LLVM=1 ARCH=arm64 Image'.

> Can you perhaps share your config so that someone else could repro and
> take a look?

Sure. Not sure how I can share the giant config without bombarding all
the recipients. Let me just send to you privately first.

> Happy to follow up in our issue tracker, too.
> https://github.com/ClangBuiltLinux/linux/issues
>
>>
>> Mark them __always_inline so the compiler can never outline them.
>>
>> Signed-off-by: Hongyan Xia <hongyan.xia@transsion.com>
>> ---
>>   arch/arm64/include/asm/esr.h       | 2 +-
>>   arch/arm64/include/asm/percpu.h    | 2 +-
>>   arch/arm64/include/asm/preempt.h   | 4 ++--
>>   arch/arm64/include/asm/ptrace.h    | 4 ++--
>>   arch/arm64/kernel/debug-monitors.c | 2 +-
>>   include/linux/kprobes.h            | 8 ++++----
>
> It might not be appropriate for the changes to kprobes.h to go through
> the arm64 tree, but maybe it is?

I see Will has replied, so this might be a question for Kprobe
maintainers. I do wonder that, if I see this in clang-19 compiling for
arm64 without any special configs, eventually it might happen for other
people after moving to clang-19?