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

From: "nobuta.keiya@fujitsu.com" <nobuta.keiya@fujitsu.com>
To: "'madvenka@linux.microsoft.com'" <madvenka@linux.microsoft.com>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"broonie@kernel.org" <broonie@kernel.org>,
	"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
	"ardb@kernel.org" <ardb@kernel.org>,
	"sjitindarsingh@gmail.com" <sjitindarsingh@gmail.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will@kernel.org" <will@kernel.org>,
	"jmorris@namei.org" <jmorris@namei.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"live-patching@vger.kernel.org" <live-patching@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v10 06/11] arm64: Make profile_pc() use arch_stack_walk()
Date: Mon, 25 Oct 2021 02:18:22 +0000	[thread overview]
Message-ID: <TY2PR01MB5257A65FD9D19AE3516D447285839@TY2PR01MB5257.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <20211015025847.17694-7-madvenka@linux.microsoft.com>

Hi,

> -----Original Message-----
> From: madvenka@linux.microsoft.com <madvenka@linux.microsoft.com>
> Sent: Friday, October 15, 2021 11:59 AM
> To: mark.rutland@arm.com; broonie@kernel.org; jpoimboe@redhat.com; ardb@kernel.org; Nobuta, Keiya/信田 圭哉
> <nobuta.keiya@fujitsu.com>; sjitindarsingh@gmail.com; catalin.marinas@arm.com; will@kernel.org; jmorris@namei.org;
> linux-arm-kernel@lists.infradead.org; live-patching@vger.kernel.org; linux-kernel@vger.kernel.org;
> madvenka@linux.microsoft.com
> Subject: [PATCH v10 06/11] arm64: Make profile_pc() use arch_stack_walk()
> 
> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
> 
> 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@linux.microsoft.com>
> ---
>  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