From: Jungseok Lee <jungseoklee85@gmail.com>
To: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mark Rutland <Mark.Rutland@arm.com>,
Catalin Marinas <Catalin.Marinas@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"broonie@kernel.org" <broonie@kernel.org>,
"david.griego@linaro.org" <david.griego@linaro.org>,
"olof@lixom.net" <olof@lixom.net>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace()
Date: Tue, 21 Jul 2015 23:34:21 +0900 [thread overview]
Message-ID: <39628AC3-A593-4E48-89A5-D95F22734009@gmail.com> (raw)
In-Reply-To: <55AE1E5F.6060407@linaro.org>
On Jul 21, 2015, at 7:26 PM, AKASHI Takahiro wrote:
> On 07/21/2015 08:53 AM, AKASHI Takahiro wrote:
>> Hi
>>
>> So i don't have to repost my patch here. Please use the original
>> commit log message[1/3] as is.
>> But please keep in mind that there is still an issue that I mentioned
>> in the cover letter; 'Size' field is inaccurate.
>> <reported size> = <its own dynamic local variables>
>> + <child's local variables>
>> and
>> <real size> = <reported size> + <its local variables>
>> - <child's local variables>
>> where "dynamic" means, for example, a variable allocated like the below:
>> int foo(int num) {
>> int array[num];
>> ...
>> }
>> (See more details in my ascii art.)
>>
>> Such usage is seldom seen in the kernel, and <reported size> is
>> likely equal to <child's local variables>. In other words, we will
>> see one-line *displacement* in most cases.
>
> Well, I have a quick fix now, but it looks ugly.
AFAIU, stack_max_size would be more accurate if a separate stack
is introduced for interrupt context. However, it might be unnecessary
at this point due to complexity.
> In addition, I found another issue; With function_graph tracer,
> the output is like:
> # cat /sys/kernel/tracing/stack_trace
> Depth Size Location (78 entries)
> ----- ---- --------
> 0) 6184 32 update_min_vruntime+0x14/0x74
> 1) 6152 48 update_curr+0x6c/0x150
> 2) 6104 128 enqueue_task_fair+0x2f4/0xb9c
> 3) 5976 48 enqueue_task+0x48/0x90
> ...
> 18) 5160 112 hrtimer_interrupt+0xa0/0x214
> 19) 5048 32 arch_timer_handler_phys+0x38/0x48
> 20) 5016 0 ftrace_graph_caller+0x2c/0x30
> 21) 5016 64 ftrace_graph_caller+0x2c/0x30
> 22) 4952 32 ftrace_graph_caller+0x2c/0x30
> 23) 4920 64 ftrace_graph_caller+0x2c/0x30
> ...
>
> Since, with function_graph tracer, we modify LR register in a stack frame
> when we enter into a function, we have to manage such special cases
> in save_stack_trace() or check_stack() as x86 does in
> print_ftrace_graph_addr().
I should have run it with function_graph. The issue is reproduced easily
on my environment. I don't see other issues yet when enabling other tracers.
Best Regards
Jungseok Lee
WARNING: multiple messages have this Message-ID (diff)
From: jungseoklee85@gmail.com (Jungseok Lee)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 2/3] arm64: refactor save_stack_trace()
Date: Tue, 21 Jul 2015 23:34:21 +0900 [thread overview]
Message-ID: <39628AC3-A593-4E48-89A5-D95F22734009@gmail.com> (raw)
In-Reply-To: <55AE1E5F.6060407@linaro.org>
On Jul 21, 2015, at 7:26 PM, AKASHI Takahiro wrote:
> On 07/21/2015 08:53 AM, AKASHI Takahiro wrote:
>> Hi
>>
>> So i don't have to repost my patch here. Please use the original
>> commit log message[1/3] as is.
>> But please keep in mind that there is still an issue that I mentioned
>> in the cover letter; 'Size' field is inaccurate.
>> <reported size> = <its own dynamic local variables>
>> + <child's local variables>
>> and
>> <real size> = <reported size> + <its local variables>
>> - <child's local variables>
>> where "dynamic" means, for example, a variable allocated like the below:
>> int foo(int num) {
>> int array[num];
>> ...
>> }
>> (See more details in my ascii art.)
>>
>> Such usage is seldom seen in the kernel, and <reported size> is
>> likely equal to <child's local variables>. In other words, we will
>> see one-line *displacement* in most cases.
>
> Well, I have a quick fix now, but it looks ugly.
AFAIU, stack_max_size would be more accurate if a separate stack
is introduced for interrupt context. However, it might be unnecessary
at this point due to complexity.
> In addition, I found another issue; With function_graph tracer,
> the output is like:
> # cat /sys/kernel/tracing/stack_trace
> Depth Size Location (78 entries)
> ----- ---- --------
> 0) 6184 32 update_min_vruntime+0x14/0x74
> 1) 6152 48 update_curr+0x6c/0x150
> 2) 6104 128 enqueue_task_fair+0x2f4/0xb9c
> 3) 5976 48 enqueue_task+0x48/0x90
> ...
> 18) 5160 112 hrtimer_interrupt+0xa0/0x214
> 19) 5048 32 arch_timer_handler_phys+0x38/0x48
> 20) 5016 0 ftrace_graph_caller+0x2c/0x30
> 21) 5016 64 ftrace_graph_caller+0x2c/0x30
> 22) 4952 32 ftrace_graph_caller+0x2c/0x30
> 23) 4920 64 ftrace_graph_caller+0x2c/0x30
> ...
>
> Since, with function_graph tracer, we modify LR register in a stack frame
> when we enter into a function, we have to manage such special cases
> in save_stack_trace() or check_stack() as x86 does in
> print_ftrace_graph_addr().
I should have run it with function_graph. The issue is reproduced easily
on my environment. I don't see other issues yet when enabling other tracers.
Best Regards
Jungseok Lee
next prev parent reply other threads:[~2015-07-21 14:34 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-13 5:29 [RFC 0/3] arm64: ftrace: fix incorrect output from stack tracer AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 1/3] ftrace: adjust a function's pc to search for in check_stack() for arm64 AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 15:24 ` Steven Rostedt
2015-07-13 15:24 ` Steven Rostedt
2015-07-15 0:22 ` AKASHI Takahiro
2015-07-15 0:22 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-14 12:47 ` Jungseok Lee
2015-07-14 12:47 ` Jungseok Lee
2015-07-14 13:31 ` Steven Rostedt
2015-07-14 13:31 ` Steven Rostedt
2015-07-15 0:20 ` AKASHI Takahiro
2015-07-15 0:20 ` AKASHI Takahiro
2015-07-15 2:51 ` Steven Rostedt
2015-07-15 2:51 ` Steven Rostedt
2015-07-15 11:41 ` AKASHI Takahiro
2015-07-15 11:41 ` AKASHI Takahiro
2015-07-15 14:55 ` Steven Rostedt
2015-07-15 14:55 ` Steven Rostedt
2015-07-15 16:13 ` Steven Rostedt
2015-07-15 16:13 ` Steven Rostedt
2015-07-16 0:27 ` AKASHI Takahiro
2015-07-16 0:27 ` AKASHI Takahiro
2015-07-16 1:08 ` AKASHI Takahiro
2015-07-16 1:08 ` AKASHI Takahiro
2015-07-16 1:38 ` Steven Rostedt
2015-07-16 1:38 ` Steven Rostedt
2015-07-17 10:46 ` Will Deacon
2015-07-17 10:46 ` Will Deacon
2015-07-16 13:29 ` Jungseok Lee
2015-07-16 13:29 ` Jungseok Lee
2015-07-16 13:54 ` Jungseok Lee
2015-07-16 13:54 ` Jungseok Lee
2015-07-16 14:24 ` Steven Rostedt
2015-07-16 14:24 ` Steven Rostedt
2015-07-16 15:01 ` Jungseok Lee
2015-07-16 15:01 ` Jungseok Lee
2015-07-16 15:31 ` Steven Rostedt
2015-07-16 15:31 ` Steven Rostedt
2015-07-16 15:52 ` Jungseok Lee
2015-07-16 15:52 ` Jungseok Lee
2015-07-16 20:22 ` Steven Rostedt
2015-07-16 20:22 ` Steven Rostedt
2015-07-17 2:49 ` AKASHI Takahiro
2015-07-17 2:49 ` AKASHI Takahiro
2015-07-17 3:21 ` Steven Rostedt
2015-07-17 3:21 ` Steven Rostedt
2015-07-16 16:16 ` Steven Rostedt
2015-07-16 16:16 ` Steven Rostedt
2015-07-17 12:40 ` Mark Rutland
2015-07-17 12:40 ` Mark Rutland
2015-07-17 12:51 ` Steven Rostedt
2015-07-17 12:51 ` Steven Rostedt
2015-07-17 13:00 ` Steven Rostedt
2015-07-17 13:00 ` Steven Rostedt
2015-07-17 14:28 ` Jungseok Lee
2015-07-17 14:28 ` Jungseok Lee
2015-07-17 14:41 ` Steven Rostedt
2015-07-17 14:41 ` Steven Rostedt
2015-07-17 14:59 ` Jungseok Lee
2015-07-17 14:59 ` Jungseok Lee
2015-07-17 15:34 ` Jungseok Lee
2015-07-17 15:34 ` Jungseok Lee
2015-07-17 16:01 ` Steven Rostedt
2015-07-17 16:01 ` Steven Rostedt
2015-07-20 16:20 ` Will Deacon
2015-07-20 16:20 ` Will Deacon
2015-07-20 23:53 ` AKASHI Takahiro
2015-07-20 23:53 ` AKASHI Takahiro
2015-07-21 10:26 ` AKASHI Takahiro
2015-07-21 10:26 ` AKASHI Takahiro
2015-07-21 14:34 ` Jungseok Lee [this message]
2015-07-21 14:34 ` Jungseok Lee
2015-08-03 9:09 ` Will Deacon
2015-08-03 9:09 ` Will Deacon
2015-08-03 14:01 ` Steven Rostedt
2015-08-03 14:01 ` Steven Rostedt
2015-08-03 14:04 ` Will Deacon
2015-08-03 14:04 ` Will Deacon
2015-08-03 16:30 ` Jungseok Lee
2015-08-03 16:30 ` Jungseok Lee
2015-08-03 16:57 ` Steven Rostedt
2015-08-03 16:57 ` Steven Rostedt
2015-08-03 17:22 ` Jungseok Lee
2015-08-03 17:22 ` Jungseok Lee
2015-08-03 17:32 ` Steven Rostedt
2015-08-03 17:32 ` Steven Rostedt
2015-08-04 7:41 ` AKASHI Takahiro
2015-08-04 7:41 ` AKASHI Takahiro
2015-07-17 2:04 ` AKASHI Takahiro
2015-07-17 2:04 ` AKASHI Takahiro
2015-07-17 14:38 ` Jungseok Lee
2015-07-17 14:38 ` Jungseok Lee
2015-07-16 14:28 ` Mark Rutland
2015-07-16 14:28 ` Mark Rutland
2015-07-16 14:34 ` Steven Rostedt
2015-07-16 14:34 ` Steven Rostedt
2015-07-17 2:09 ` AKASHI Takahiro
2015-07-17 2:09 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 3/3] arm64: ftrace: mcount() should not create a stack frame AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 15:01 ` [RFC 0/3] arm64: ftrace: fix incorrect output from stack tracer Jungseok Lee
2015-07-13 15:01 ` Jungseok Lee
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