linux-kernel - Re: [PATCH 6/7] x86: Always inline on_thread_stack() and current_top_of

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Date:   Mon, 30 May 2022 15:21:37 +0200
From:   Marco Elver <elver@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, jpoimboe@...hat.com, linux-kernel@...r.kernel.org,
        jbaron@...mai.com, rostedt@...dmis.org, ardb@...nel.org,
        mark.rutland@....com
Subject: Re: [PATCH 6/7] x86: Always inline on_thread_stack() and
 current_top_of_stack()

On Thu, May 26, 2022 at 12:52PM +0200, Peter Zijlstra wrote:
> Becaues GCC clearly lost it's marbles again...
> 

This must have been with some of the big sanitizers though, right?

> vmlinux.o: warning: objtool: enter_from_user_mode+0x4e: call to on_thread_stack() leaves .noinstr.text section
> vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x53: call to on_thread_stack() leaves .noinstr.text section
> vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare+0x4e: call to on_thread_stack() leaves .noinstr.text section
> vmlinux.o: warning: objtool: irqentry_enter_from_user_mode+0x4e: call to on_thread_stack() leaves .noinstr.text section
> 
> vmlinux.o: warning: objtool: enter_from_user_mode+0x4e: call to current_top_of_stack() leaves .noinstr.text section
> vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x53: call to current_top_of_stack() leaves .noinstr.text section
> vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare+0x4e: call to current_top_of_stack() leaves .noinstr.text section
> vmlinux.o: warning: objtool: irqentry_enter_from_user_mode+0x4e: call to current_top_of_stack() leaves .noinstr.text section
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Acked-by: Marco Elver <elver@...gle.com>

> ---
>  arch/x86/include/asm/processor.h |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -559,7 +559,7 @@ static __always_inline void native_swapg
>  #endif
>  }
>  
> -static inline unsigned long current_top_of_stack(void)
> +static __always_inline unsigned long current_top_of_stack(void)
>  {
>  	/*
>  	 *  We can't read directly from tss.sp0: sp0 on x86_32 is special in
> @@ -569,7 +569,7 @@ static inline unsigned long current_top_
>  	return this_cpu_read_stable(cpu_current_top_of_stack);
>  }
>  
> -static inline bool on_thread_stack(void)
> +static __always_inline bool on_thread_stack(void)
>  {
>  	return (unsigned long)(current_top_of_stack() -
>  			       current_stack_pointer) < THREAD_SIZE;
> 
>