RE: [PATCH v10 06/11] arm64: Make profile_pc() use arch_stack_walk()

[nobuta.keiya@xxxxxxxxxxx]

Hi,

> -----Original Message-----
> From: madvenka@xxxxxxxxxxxxxxxxxxx <madvenka@xxxxxxxxxxxxxxxxxxx>
> Sent: Friday, October 15, 2021 11:59 AM
> To: mark.rutland@xxxxxxx; broonie@xxxxxxxxxx; jpoimboe@xxxxxxxxxx; ardb@xxxxxxxxxx; Nobuta, Keiya/信田 圭哉
> <nobuta.keiya@xxxxxxxxxxx>; sjitindarsingh@xxxxxxxxx; catalin.marinas@xxxxxxx; will@xxxxxxxxxx; jmorris@xxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; live-patching@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> madvenka@xxxxxxxxxxxxxxxxxxx
> Subject: [PATCH v10 06/11] arm64: Make profile_pc() use arch_stack_walk()
> 
> From: "Madhavan T. Venkataraman" <madvenka@xxxxxxxxxxxxxxxxxxx>
> 
> Currently, profile_pc() in ARM64 code walks the stack using
> start_backtrace() and unwind_frame(). Make it use arch_stack_walk() instead. This makes maintenance easier.
> 
> Signed-off-by: Madhavan T. Venkataraman <madvenka@xxxxxxxxxxxxxxxxxxx>
> ---
>  arch/arm64/kernel/time.c | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c index eebbc8d7123e..671b3038a772 100644
> --- a/arch/arm64/kernel/time.c
> +++ b/arch/arm64/kernel/time.c
> @@ -32,22 +32,26 @@
>  #include <asm/stacktrace.h>
>  #include <asm/paravirt.h>
> 
> +static bool profile_pc_cb(void *arg, unsigned long pc) {
> +	unsigned long *prof_pc = arg;
> +
> +	if (in_lock_functions(pc))
> +		return true;
> +	*prof_pc = pc;
> +	return false;
> +}
> +
>  unsigned long profile_pc(struct pt_regs *regs)  {
> -	struct stackframe frame;
> +	unsigned long prof_pc = 0;
> 
>  	if (!in_lock_functions(regs->pc))
>  		return regs->pc;
> 
> -	start_backtrace(&frame, regs->regs[29], regs->pc);
> -
> -	do {
> -		int ret = unwind_frame(NULL, &frame);
> -		if (ret < 0)
> -			return 0;
> -	} while (in_lock_functions(frame.pc));
> +	arch_stack_walk(profile_pc_cb, &prof_pc, current, regs);
> 
> -	return frame.pc;
> +	return prof_pc;
>  }
>  EXPORT_SYMBOL(profile_pc);
> 
> --
> 2.25.1


I've got build error with CONFIG_ACPI=n:
====
arch/arm64/kernel/time.c: In function 'profile_pc':
arch/arm64/kernel/time.c:52:2: error: implicit declaration of function 'arch_stack_walk' [-Werror=implicit-function-declaration]
   52 |  arch_stack_walk(profile_pc_cb, &prof_pc, current, regs);
      |  ^~~~~~~~~~~~~~~
====

I think it should include <linux/stacktrace.h> instead of <asm/stacktrace.h>.


Thanks,
Keiya