* [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk.
@ 2019-05-30 15:06 ` l00383200
0 siblings, 0 replies; 6+ messages in thread
From: l00383200 @ 2019-05-30 15:06 UTC (permalink / raw)
To: rmk+kernel, tglx
Cc: peterz, gregkh, linux-arm-kernel, linux-kernel, liucheng32
Without optimization, both save_stack_trace_tsk and __save_stack_trace
will have stacktrace information in ARM32.
In this situation, "data.skip += 2" operation will skip the first two layers,
which may make the stacktrace strange and different from other architectures.
A simple example is as follows:
In ARM32 architecture:
[<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
[<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
[<ffffff800838aca8>] seq_read+0x130/0x420
[<ffffff8008365c54>] __vfs_read+0x60/0x11c
[<ffffff80083665dc>] vfs_read+0x8c/0x140
[<ffffff800836717c>] SyS_read+0x6c/0xcc
[<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
[<ffffffffffffffff>] 0xffffffffffffffff
In some other architectures(ARM64):
[<ffffff8008209be0>] save_stack_trace_tsk+0x0/0xf0
[<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
[<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
[<ffffff800838aca8>] seq_read+0x130/0x420
[<ffffff8008365c54>] __vfs_read+0x60/0x11c
[<ffffff80083665dc>] vfs_read+0x8c/0x140
[<ffffff800836717c>] SyS_read+0x6c/0xcc
[<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
[<ffffffffffffffff>] 0xffffffffffffffff
Therefore, we'd better just jump only one layer to ensure accuracy and consistency.
Signed-off-by: liucheng <liucheng32@huawei.com>
---
arch/arm/kernel/stacktrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 71778bb..bb3da38 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -125,7 +125,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
#endif
} else {
/* We don't want this function nor the caller */
- data.skip += 2;
+ data.skip += 1;
frame.fp = (unsigned long)__builtin_frame_address(0);
frame.sp = current_stack_pointer;
frame.lr = (unsigned long)__builtin_return_address(0);
--
1.8.5.6
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk.
@ 2019-05-30 15:06 ` l00383200
0 siblings, 0 replies; 6+ messages in thread
From: l00383200 @ 2019-05-30 15:06 UTC (permalink / raw)
To: rmk+kernel, tglx
Cc: peterz, gregkh, linux-kernel, linux-arm-kernel, liucheng32
Without optimization, both save_stack_trace_tsk and __save_stack_trace
will have stacktrace information in ARM32.
In this situation, "data.skip += 2" operation will skip the first two layers,
which may make the stacktrace strange and different from other architectures.
A simple example is as follows:
In ARM32 architecture:
[<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
[<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
[<ffffff800838aca8>] seq_read+0x130/0x420
[<ffffff8008365c54>] __vfs_read+0x60/0x11c
[<ffffff80083665dc>] vfs_read+0x8c/0x140
[<ffffff800836717c>] SyS_read+0x6c/0xcc
[<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
[<ffffffffffffffff>] 0xffffffffffffffff
In some other architectures(ARM64):
[<ffffff8008209be0>] save_stack_trace_tsk+0x0/0xf0
[<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
[<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
[<ffffff800838aca8>] seq_read+0x130/0x420
[<ffffff8008365c54>] __vfs_read+0x60/0x11c
[<ffffff80083665dc>] vfs_read+0x8c/0x140
[<ffffff800836717c>] SyS_read+0x6c/0xcc
[<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
[<ffffffffffffffff>] 0xffffffffffffffff
Therefore, we'd better just jump only one layer to ensure accuracy and consistency.
Signed-off-by: liucheng <liucheng32@huawei.com>
---
arch/arm/kernel/stacktrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 71778bb..bb3da38 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -125,7 +125,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
#endif
} else {
/* We don't want this function nor the caller */
- data.skip += 2;
+ data.skip += 1;
frame.fp = (unsigned long)__builtin_frame_address(0);
frame.sp = current_stack_pointer;
frame.lr = (unsigned long)__builtin_return_address(0);
--
1.8.5.6
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk.
2019-05-30 15:06 ` l00383200
@ 2019-05-30 16:22 ` Russell King - ARM Linux admin
-1 siblings, 0 replies; 6+ messages in thread
From: Russell King - ARM Linux admin @ 2019-05-30 16:22 UTC (permalink / raw)
To: l00383200; +Cc: tglx, peterz, gregkh, linux-arm-kernel, linux-kernel
On Thu, May 30, 2019 at 11:06:39PM +0800, l00383200 wrote:
> Without optimization, both save_stack_trace_tsk and __save_stack_trace
> will have stacktrace information in ARM32.
>
> In this situation, "data.skip += 2" operation will skip the first two layers,
> which may make the stacktrace strange and different from other architectures.
>
> A simple example is as follows:
> In ARM32 architecture:
> [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> [<ffffff800838aca8>] seq_read+0x130/0x420
> [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> [<ffffff80083665dc>] vfs_read+0x8c/0x140
> [<ffffff800836717c>] SyS_read+0x6c/0xcc
> [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> In some other architectures(ARM64):
> [<ffffff8008209be0>] save_stack_trace_tsk+0x0/0xf0
> [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> [<ffffff800838aca8>] seq_read+0x130/0x420
> [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> [<ffffff80083665dc>] vfs_read+0x8c/0x140
> [<ffffff800836717c>] SyS_read+0x6c/0xcc
> [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Therefore, we'd better just jump only one layer to ensure accuracy and consistency.
Why do we want to log the function we called to save the stack trace
_in_ the stack trace? What useful purpose does it serve?
I've always taken the attitude that if we want a stack trace from a
certain point in the function, then that's the point that the stack
trace should start. It's entirely sensible.
>
> Signed-off-by: liucheng <liucheng32@huawei.com>
> ---
> arch/arm/kernel/stacktrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
> index 71778bb..bb3da38 100644
> --- a/arch/arm/kernel/stacktrace.c
> +++ b/arch/arm/kernel/stacktrace.c
> @@ -125,7 +125,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
> #endif
> } else {
> /* We don't want this function nor the caller */
> - data.skip += 2;
> + data.skip += 1;
> frame.fp = (unsigned long)__builtin_frame_address(0);
> frame.sp = current_stack_pointer;
> frame.lr = (unsigned long)__builtin_return_address(0);
> --
> 1.8.5.6
>
>
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk.
@ 2019-05-30 16:22 ` Russell King - ARM Linux admin
0 siblings, 0 replies; 6+ messages in thread
From: Russell King - ARM Linux admin @ 2019-05-30 16:22 UTC (permalink / raw)
To: l00383200; +Cc: peterz, gregkh, tglx, linux-kernel, linux-arm-kernel
On Thu, May 30, 2019 at 11:06:39PM +0800, l00383200 wrote:
> Without optimization, both save_stack_trace_tsk and __save_stack_trace
> will have stacktrace information in ARM32.
>
> In this situation, "data.skip += 2" operation will skip the first two layers,
> which may make the stacktrace strange and different from other architectures.
>
> A simple example is as follows:
> In ARM32 architecture:
> [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> [<ffffff800838aca8>] seq_read+0x130/0x420
> [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> [<ffffff80083665dc>] vfs_read+0x8c/0x140
> [<ffffff800836717c>] SyS_read+0x6c/0xcc
> [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> In some other architectures(ARM64):
> [<ffffff8008209be0>] save_stack_trace_tsk+0x0/0xf0
> [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> [<ffffff800838aca8>] seq_read+0x130/0x420
> [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> [<ffffff80083665dc>] vfs_read+0x8c/0x140
> [<ffffff800836717c>] SyS_read+0x6c/0xcc
> [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Therefore, we'd better just jump only one layer to ensure accuracy and consistency.
Why do we want to log the function we called to save the stack trace
_in_ the stack trace? What useful purpose does it serve?
I've always taken the attitude that if we want a stack trace from a
certain point in the function, then that's the point that the stack
trace should start. It's entirely sensible.
>
> Signed-off-by: liucheng <liucheng32@huawei.com>
> ---
> arch/arm/kernel/stacktrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
> index 71778bb..bb3da38 100644
> --- a/arch/arm/kernel/stacktrace.c
> +++ b/arch/arm/kernel/stacktrace.c
> @@ -125,7 +125,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
> #endif
> } else {
> /* We don't want this function nor the caller */
> - data.skip += 2;
> + data.skip += 1;
> frame.fp = (unsigned long)__builtin_frame_address(0);
> frame.sp = current_stack_pointer;
> frame.lr = (unsigned long)__builtin_return_address(0);
> --
> 1.8.5.6
>
>
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk.
2019-05-30 16:22 ` Russell King - ARM Linux admin
@ 2019-05-31 8:27 ` Peter Zijlstra
-1 siblings, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2019-05-31 8:27 UTC (permalink / raw)
To: Russell King - ARM Linux admin
Cc: l00383200, tglx, gregkh, linux-arm-kernel, linux-kernel
On Thu, May 30, 2019 at 05:22:19PM +0100, Russell King - ARM Linux admin wrote:
> On Thu, May 30, 2019 at 11:06:39PM +0800, l00383200 wrote:
> > Without optimization, both save_stack_trace_tsk and __save_stack_trace
> > will have stacktrace information in ARM32.
> >
> > In this situation, "data.skip += 2" operation will skip the first two layers,
> > which may make the stacktrace strange and different from other architectures.
> >
> > A simple example is as follows:
> > In ARM32 architecture:
> > [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> > [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> > [<ffffff800838aca8>] seq_read+0x130/0x420
> > [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> > [<ffffff80083665dc>] vfs_read+0x8c/0x140
> > [<ffffff800836717c>] SyS_read+0x6c/0xcc
> > [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> > [<ffffffffffffffff>] 0xffffffffffffffff
> >
> > In some other architectures(ARM64):
> > [<ffffff8008209be0>] save_stack_trace_tsk+0x0/0xf0
> > [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> > [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> > [<ffffff800838aca8>] seq_read+0x130/0x420
> > [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> > [<ffffff80083665dc>] vfs_read+0x8c/0x140
> > [<ffffff800836717c>] SyS_read+0x6c/0xcc
> > [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> > [<ffffffffffffffff>] 0xffffffffffffffff
> >
> > Therefore, we'd better just jump only one layer to ensure accuracy and consistency.
>
> Why do we want to log the function we called to save the stack trace
> _in_ the stack trace? What useful purpose does it serve?
>
> I've always taken the attitude that if we want a stack trace from a
> certain point in the function, then that's the point that the stack
> trace should start. It's entirely sensible.
Agreed, also the .skip interface sucks and is slated for replacement
(whenever we get around to it).
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk.
@ 2019-05-31 8:27 ` Peter Zijlstra
0 siblings, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2019-05-31 8:27 UTC (permalink / raw)
To: Russell King - ARM Linux admin
Cc: gregkh, tglx, l00383200, linux-arm-kernel, linux-kernel
On Thu, May 30, 2019 at 05:22:19PM +0100, Russell King - ARM Linux admin wrote:
> On Thu, May 30, 2019 at 11:06:39PM +0800, l00383200 wrote:
> > Without optimization, both save_stack_trace_tsk and __save_stack_trace
> > will have stacktrace information in ARM32.
> >
> > In this situation, "data.skip += 2" operation will skip the first two layers,
> > which may make the stacktrace strange and different from other architectures.
> >
> > A simple example is as follows:
> > In ARM32 architecture:
> > [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> > [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> > [<ffffff800838aca8>] seq_read+0x130/0x420
> > [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> > [<ffffff80083665dc>] vfs_read+0x8c/0x140
> > [<ffffff800836717c>] SyS_read+0x6c/0xcc
> > [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> > [<ffffffffffffffff>] 0xffffffffffffffff
> >
> > In some other architectures(ARM64):
> > [<ffffff8008209be0>] save_stack_trace_tsk+0x0/0xf0
> > [<ffffff80083cb3f8>] proc_pid_stack+0xac/0x12c
> > [<ffffff80083c7c70>] proc_single_show+0x5c/0xa8
> > [<ffffff800838aca8>] seq_read+0x130/0x420
> > [<ffffff8008365c54>] __vfs_read+0x60/0x11c
> > [<ffffff80083665dc>] vfs_read+0x8c/0x140
> > [<ffffff800836717c>] SyS_read+0x6c/0xcc
> > [<ffffff8008202cb8>] __sys_trace_return+0x0/0x4
> > [<ffffffffffffffff>] 0xffffffffffffffff
> >
> > Therefore, we'd better just jump only one layer to ensure accuracy and consistency.
>
> Why do we want to log the function we called to save the stack trace
> _in_ the stack trace? What useful purpose does it serve?
>
> I've always taken the attitude that if we want a stack trace from a
> certain point in the function, then that's the point that the stack
> trace should start. It's entirely sensible.
Agreed, also the .skip interface sucks and is slated for replacement
(whenever we get around to it).
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-05-31 8:27 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-30 15:06 [PATCH] Stacktrace in ARM32 architecture has jumped the first 2 layers, which may ignore the display of save_stack_trace_tsk l00383200
2019-05-30 15:06 ` l00383200
2019-05-30 16:22 ` Russell King - ARM Linux admin
2019-05-30 16:22 ` Russell King - ARM Linux admin
2019-05-31 8:27 ` Peter Zijlstra
2019-05-31 8:27 ` Peter Zijlstra
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