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

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

[Hongyan Xia]

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.

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 ++++----
 6 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index f816f5d77f1a..a75bfdb7e5fe 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -437,7 +437,7 @@
 #ifndef __ASSEMBLER__
 #include <asm/types.h>
 
-static inline unsigned long esr_brk_comment(unsigned long esr)
+static __always_inline unsigned long esr_brk_comment(unsigned long esr)
 {
 	return esr & ESR_ELx_BRK64_ISS_COMMENT_MASK;
 }
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index b57b2bb00967..d4cae47fde8c 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -29,7 +29,7 @@ static inline unsigned long __hyp_my_cpu_offset(void)
 	return read_sysreg(tpidr_el2);
 }
 
-static inline unsigned long __kern_my_cpu_offset(void)
+static __always_inline unsigned long __kern_my_cpu_offset(void)
 {
 	unsigned long off;
 
diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h
index 932ea4b62042..326f221c3f56 100644
--- a/arch/arm64/include/asm/preempt.h
+++ b/arch/arm64/include/asm/preempt.h
@@ -41,14 +41,14 @@ static inline bool test_preempt_need_resched(void)
 	return !current_thread_info()->preempt.need_resched;
 }
 
-static inline void __preempt_count_add(int val)
+static __always_inline void __preempt_count_add(int val)
 {
 	u32 pc = READ_ONCE(current_thread_info()->preempt.count);
 	pc += val;
 	WRITE_ONCE(current_thread_info()->preempt.count, pc);
 }
 
-static inline void __preempt_count_sub(int val)
+static __always_inline void __preempt_count_sub(int val)
 {
 	u32 pc = READ_ONCE(current_thread_info()->preempt.count);
 	pc -= val;
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 39582511ad72..460726224299 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -336,11 +336,11 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 struct task_struct;
 int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task);
 
-static inline unsigned long instruction_pointer(struct pt_regs *regs)
+static __always_inline unsigned long instruction_pointer(struct pt_regs *regs)
 {
 	return regs->pc;
 }
-static inline void instruction_pointer_set(struct pt_regs *regs,
+static __always_inline void instruction_pointer_set(struct pt_regs *regs,
 		unsigned long val)
 {
 	regs->pc = val;
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index a970ab6327cd..66cb8151f5df 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -146,7 +146,7 @@ postcore_initcall(debug_monitors_init);
 /*
  * Single step API and exception handling.
  */
-static void set_user_regs_spsr_ss(struct user_pt_regs *regs)
+static __always_inline void set_user_regs_spsr_ss(struct user_pt_regs *regs)
 {
 	regs->pstate |= DBG_SPSR_SS;
 }
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 8c4f3bb24429..5880445ed0f0 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -384,17 +384,17 @@ static inline void kprobe_ftrace_kill(void) {}
 struct kprobe *get_kprobe(void *addr);
 
 /* kprobe_running() will just return the current_kprobe on this CPU */
-static inline struct kprobe *kprobe_running(void)
+static __always_inline struct kprobe *kprobe_running(void)
 {
 	return __this_cpu_read(current_kprobe);
 }
 
-static inline void reset_current_kprobe(void)
+static __always_inline void reset_current_kprobe(void)
 {
 	__this_cpu_write(current_kprobe, NULL);
 }
 
-static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
+static __always_inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 {
 	return this_cpu_ptr(&kprobe_ctlblk);
 }
@@ -449,7 +449,7 @@ static inline struct kprobe *get_kprobe(void *addr)
 {
 	return NULL;
 }
-static inline struct kprobe *kprobe_running(void)
+static __always_inline struct kprobe *kprobe_running(void)
 {
 	return NULL;
 }
-- 
2.47.3

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

[Nick Desaulniers]

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.

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

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?

-- 
Thanks,
~Nick Desaulniers

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

[Will Deacon]

On Mon, Jul 27, 2026 at 12:22:32PM -0700, Nick Desaulniers wrote:
> On Mon, Jul 27, 2026 at 5:25 AM Hongyan Xia <hongyan.xia@transsion.com> wrote:
> >  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?

They look pretty trivial, so we can take 'em with Masami's Ack once the
rest of the series has been reviewed.

Will

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

[Hongyan Xia]

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?

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

[Steven Rostedt]

Masami,


On Mon, 27 Jul 2026 12:25:48 +0000
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.
> 
> 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 ++++----

Are you OK with this patch? If so, can you ack it?

-- Steve

>  6 files changed, 11 insertions(+), 11 deletions(-)
> 

[..]

> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 8c4f3bb24429..5880445ed0f0 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -384,17 +384,17 @@ static inline void kprobe_ftrace_kill(void) {}
>  struct kprobe *get_kprobe(void *addr);
>  
>  /* kprobe_running() will just return the current_kprobe on this CPU */
> -static inline struct kprobe *kprobe_running(void)
> +static __always_inline struct kprobe *kprobe_running(void)
>  {
>  	return __this_cpu_read(current_kprobe);
>  }
>  
> -static inline void reset_current_kprobe(void)
> +static __always_inline void reset_current_kprobe(void)
>  {
>  	__this_cpu_write(current_kprobe, NULL);
>  }
>  
> -static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
> +static __always_inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
>  {
>  	return this_cpu_ptr(&kprobe_ctlblk);
>  }
> @@ -449,7 +449,7 @@ static inline struct kprobe *get_kprobe(void *addr)
>  {
>  	return NULL;
>  }
> -static inline struct kprobe *kprobe_running(void)
> +static __always_inline struct kprobe *kprobe_running(void)
>  {
>  	return NULL;
>  }

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

[Masami Hiramatsu]

On Wed, 29 Jul 2026 14:08:46 -0400
Steven Rostedt <steven@rostedt.org> wrote:

> 
> Masami,
> 
> 
> On Mon, 27 Jul 2026 12:25:48 +0000
> 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.
> > 
> > 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 ++++----
> 
> Are you OK with this patch? If so, can you ack it?

Yeah, this patch looks good to me. Anyway these are expected to be
inlined.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

For other patches, Sashiko noted some comments, I need to check it.

Thank you,

> 
> -- Steve
> 
> >  6 files changed, 11 insertions(+), 11 deletions(-)
> > 
> 
> [..]
> 
> > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> > index 8c4f3bb24429..5880445ed0f0 100644
> > --- a/include/linux/kprobes.h
> > +++ b/include/linux/kprobes.h
> > @@ -384,17 +384,17 @@ static inline void kprobe_ftrace_kill(void) {}
> >  struct kprobe *get_kprobe(void *addr);
> >  
> >  /* kprobe_running() will just return the current_kprobe on this CPU */
> > -static inline struct kprobe *kprobe_running(void)
> > +static __always_inline struct kprobe *kprobe_running(void)
> >  {
> >  	return __this_cpu_read(current_kprobe);
> >  }
> >  
> > -static inline void reset_current_kprobe(void)
> > +static __always_inline void reset_current_kprobe(void)
> >  {
> >  	__this_cpu_write(current_kprobe, NULL);
> >  }
> >  
> > -static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
> > +static __always_inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
> >  {
> >  	return this_cpu_ptr(&kprobe_ctlblk);
> >  }
> > @@ -449,7 +449,7 @@ static inline struct kprobe *get_kprobe(void *addr)
> >  {
> >  	return NULL;
> >  }
> > -static inline struct kprobe *kprobe_running(void)
> > +static __always_inline struct kprobe *kprobe_running(void)
> >  {
> >  	return NULL;
> >  }
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>