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

Madhavan T. Venkataraman
2021-10-27T16:11:05Z

On 10/24/21 9:18 PM, nobuta.keiya@fujitsu.com wrote:
> 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>.
>

OK. I will fix this.
Thanks for catching this.

Madhavan