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[PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object

Jeff Xie posted 4 patches 3 years, 10 months ago
There is a newer version of this series
Documentation/trace/events.rst                |  87 +++
include/linux/trace_events.h                  |   1 +
kernel/trace/Kconfig                          |  10 +
kernel/trace/Makefile                         |   1 +
kernel/trace/trace.c                          |  11 +
kernel/trace/trace.h                          |  21 +
kernel/trace/trace_entries.h                  |  18 +
kernel/trace/trace_events_trigger.c           |   5 +-
kernel/trace/trace_object.c                   | 611 ++++++++++++++++++
kernel/trace/trace_output.c                   |  40 ++
.../ftrace/test.d/trigger/trigger-objtrace.tc |  41 ++
11 files changed, 844 insertions(+), 2 deletions(-)
create mode 100644 kernel/trace/trace_object.c
create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-objtrace.tc
[PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object
Posted by Jeff Xie 3 years, 10 months ago 
Introduce a method based on function tracer to trace any object and get
the value of the object dynamically. the object can be obtained from the
dynamic event (kprobe_event/uprobe_event) or the static event(tracepoint).

Usage:
When using the kprobe event, only need to set the objtrace(a new trigger),
we can get the value of the object. The object is from the setting of the 
kprobe event.

For example:
For the function bio_add_page():

int bio_add_page(struct bio *bio, struct page *page,
	unsigned int len, unsigned int offset)

Firstly, we can set the base of the object, thus the first string "arg1"
stands for the value of the first parameter of this function bio_add_gage(),

# echo 'p bio_add_page arg1=$arg1' > ./kprobe_events

Secondly, we can get the value dynamically based on above object. 

find the offset of the bi_size in struct bio:
$ gdb vmlinux
(gdb) p &(((struct bio *)0)->bi_iter.bi_size)
$1 = (unsigned int *) 0x28

# echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \
	p_bio_add_page_0/trigger

# cd /sys/kernel/debug/tracing/
# echo 'p bio_add_page arg1=$arg1' > ./kprobe_events
# echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/p_bio_add_page_0/trigger

# du -sh /test.txt
12.0K   /test.txt

# cat  /test.txt > /dev/null
# cat ./trace
# tracer: nop
#
# entries-in-buffer/entries-written: 128/128   #P:4
#
#                                _-----=> irqs-off/BH-disabled
#                               / _----=> need-resched
#                              | / _---=> hardirq/softirq
#                              || / _--=> preempt-depth
#                              ||| / _-=> migrate-disable
#                              |||| /     delay
#           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
#              | |         |   |||||     |         |
             cat-117     [002] ...1.     1.602243: __bio_try_merge_page <-bio_add_page object:0xffff88811bee4000 value:0x0
             cat-117     [002] ...1.     1.602244: __bio_add_page <-bio_add_page object:0xffff88811bee4000 value:0x0
             cat-117     [002] ...2.     1.602244: bio_add_page <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x1000
             cat-117     [002] ...1.     1.602245: __bio_try_merge_page <-bio_add_page object:0xffff88811bee4000 value:0x1000
             cat-117     [002] ...1.     1.602245: __bio_add_page <-bio_add_page object:0xffff88811bee4000 value:0x1000
             cat-117     [002] ...2.     1.602245: bio_add_page <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x2000
             cat-117     [002] ...1.     1.602245: __bio_try_merge_page <-bio_add_page object:0xffff88811bee4000 value:0x2000
             cat-117     [002] ...1.     1.602245: __bio_add_page <-bio_add_page object:0xffff88811bee4000 value:0x2000
             cat-117     [002] ...1.     1.602245: submit_bio <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602245: submit_bio_noacct <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: __submit_bio <-submit_bio_noacct object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: submit_bio_checks <-__submit_bio object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: __cond_resched <-submit_bio_checks object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: should_fail_bio <-submit_bio_checks object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: blk_mq_submit_bio <-submit_bio_noacct object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: blk_attempt_plug_merge <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602246: blk_mq_sched_bio_merge <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602247: __rcu_read_lock <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602247: __rcu_read_unlock <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
             cat-117     [002] ...1.     1.602247: __blk_mq_alloc_requests <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
          <idle>-0       [002] d..3.     1.602298: bio_endio <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602298: mpage_end_io <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602298: __read_end_io <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602300: bio_put <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602300: bio_free <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602300: mempool_free <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602300: mempool_free_slab <-blk_update_request object:0xffff88811bee4000 value:0x0
          <idle>-0       [002] d..3.     1.602300: kmem_cache_free <-blk_update_request object:0xffff88811bee4000 value:0x0
	  ...

Almost all changelogs were suggested by Masami(mhiramat@kernel.org)
and steve(rostedt@goodmis.org), thank you all so much.

v14:
- make documentation more readable and fix literal code block by Bagas Sanjaya

v13:
- remove the 's' type, since the objtrace event doesn't show the value with sign
- change the [3/4] tag with 'selftests/ftrace' instead of 'trace/objtrace'
- add 'Documentation:' tag for [4/4]

v12:
- use the %zu to print the sizeof
  Reported-by: kernel test robot <lkp@intel.com>
  Suggested-by: Nathan Chancellor <nathan@kernel.org>

v11:
- remove useless atomic counting methods for num_traced_obj
- make array objtrace_fetch_types null terminated
- add raw_spin_lock_init for obj_data_lock

v10:
- support ftrace instances
- use trace_buffer_lock_reserve instead of trace_event_buffer_lock_reserve
- a lot of cleanup work has been done mainly for event_object_trigger_parse

v9:
- fix objtrace trigger output was incomplete
- fix the objtrace trigger was removed when using the existed parameter on
  event.
- add testcase for the second fix above.

v8:
- revert to use per-cpu recursion for the function trace_object_events_call
- recover the filter when getting the value of the object
- simplify the implementation for the function get_object_value
- fix the build error

v7:
- use fixed-size array for object pool instead of list structure
- use ftrace_test_recursion_trylock for function trace hook function
- fix trace_object_ref reference count in the init_trace_object
- invoke exit_trace_object no matter whether data->ops->free is null 
  in the unregister_object_trigger
- release private_data of event_trigger_data in the trace_object_trigger_free
- remove [RFC] tag

v6:
- change the objtrace trigger syntax.
- add patchset description
- add <tracefs>/README

v5:
- add testcasts
- add check the field->size
- add lockless to search object
- describe the object trace more clearly in Kconfig

v4:
- please ignore the v4 which is the same as v3

v3:
- change the objfilter to objtrace
- add a command to the objfilter syntax
- change to get the value of the object
- use trace_find_event_field to find the field instead of using argN
- get data from @rec in the event trigger callback funciton

v2:
- adding a "objfilter" trigger to update object

Jeff Xie (4):
  trace: Add trace any kernel object
  trace/objtrace: Get the value of the object
  selftests/ftrace: Add testcases for objtrace
  Documentation: trace/objtrace: Add documentation for objtrace

 Documentation/trace/events.rst                |  87 +++
 include/linux/trace_events.h                  |   1 +
 kernel/trace/Kconfig                          |  10 +
 kernel/trace/Makefile                         |   1 +
 kernel/trace/trace.c                          |  11 +
 kernel/trace/trace.h                          |  21 +
 kernel/trace/trace_entries.h                  |  18 +
 kernel/trace/trace_events_trigger.c           |   5 +-
 kernel/trace/trace_object.c                   | 611 ++++++++++++++++++
 kernel/trace/trace_output.c                   |  40 ++
 .../ftrace/test.d/trigger/trigger-objtrace.tc |  41 ++
 11 files changed, 844 insertions(+), 2 deletions(-)
 create mode 100644 kernel/trace/trace_object.c
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-objtrace.tc


base-commit: 408d26e261b089596c0837e71d2fb4a80ea04ef3
-- 
2.25.1
Re: [PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object
Posted by Jeff Xie 3 years, 9 months ago 
Hi Steve,

I'm curious if you have any comments on this patchset ;-)

On Tue, Jun 28, 2022 at 10:56 PM Jeff Xie <xiehuan09@gmail.com> wrote:
>
> Introduce a method based on function tracer to trace any object and get
> the value of the object dynamically. the object can be obtained from the
> dynamic event (kprobe_event/uprobe_event) or the static event(tracepoint).
>
> Usage:
> When using the kprobe event, only need to set the objtrace(a new trigger),
> we can get the value of the object. The object is from the setting of the
> kprobe event.
>
> For example:
> For the function bio_add_page():
>
> int bio_add_page(struct bio *bio, struct page *page,
>         unsigned int len, unsigned int offset)
>
> Firstly, we can set the base of the object, thus the first string "arg1"
> stands for the value of the first parameter of this function bio_add_gage(),
>
> # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events
>
> Secondly, we can get the value dynamically based on above object.
>
> find the offset of the bi_size in struct bio:
> $ gdb vmlinux
> (gdb) p &(((struct bio *)0)->bi_iter.bi_size)
> $1 = (unsigned int *) 0x28
>
> # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \
>         p_bio_add_page_0/trigger
>
> # cd /sys/kernel/debug/tracing/
> # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events
> # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/p_bio_add_page_0/trigger
>
> # du -sh /test.txt
> 12.0K   /test.txt
>
> # cat  /test.txt > /dev/null
> # cat ./trace
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 128/128   #P:4
> #
> #                                _-----=> irqs-off/BH-disabled
> #                               / _----=> need-resched
> #                              | / _---=> hardirq/softirq
> #                              || / _--=> preempt-depth
> #                              ||| / _-=> migrate-disable
> #                              |||| /     delay
> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> #              | |         |   |||||     |         |
>              cat-117     [002] ...1.     1.602243: __bio_try_merge_page <-bio_add_page object:0xffff88811bee4000 value:0x0
>              cat-117     [002] ...1.     1.602244: __bio_add_page <-bio_add_page object:0xffff88811bee4000 value:0x0
>              cat-117     [002] ...2.     1.602244: bio_add_page <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x1000
>              cat-117     [002] ...1.     1.602245: __bio_try_merge_page <-bio_add_page object:0xffff88811bee4000 value:0x1000
>              cat-117     [002] ...1.     1.602245: __bio_add_page <-bio_add_page object:0xffff88811bee4000 value:0x1000
>              cat-117     [002] ...2.     1.602245: bio_add_page <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x2000
>              cat-117     [002] ...1.     1.602245: __bio_try_merge_page <-bio_add_page object:0xffff88811bee4000 value:0x2000
>              cat-117     [002] ...1.     1.602245: __bio_add_page <-bio_add_page object:0xffff88811bee4000 value:0x2000
>              cat-117     [002] ...1.     1.602245: submit_bio <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602245: submit_bio_noacct <-ext4_mpage_readpages object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: __submit_bio <-submit_bio_noacct object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: submit_bio_checks <-__submit_bio object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: __cond_resched <-submit_bio_checks object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: should_fail_bio <-submit_bio_checks object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: blk_mq_submit_bio <-submit_bio_noacct object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: blk_attempt_plug_merge <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602246: blk_mq_sched_bio_merge <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602247: __rcu_read_lock <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602247: __rcu_read_unlock <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
>              cat-117     [002] ...1.     1.602247: __blk_mq_alloc_requests <-blk_mq_submit_bio object:0xffff88811bee4000 value:0x3000
>           <idle>-0       [002] d..3.     1.602298: bio_endio <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602298: mpage_end_io <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602298: __read_end_io <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602300: bio_put <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602300: bio_free <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602300: mempool_free <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602300: mempool_free_slab <-blk_update_request object:0xffff88811bee4000 value:0x0
>           <idle>-0       [002] d..3.     1.602300: kmem_cache_free <-blk_update_request object:0xffff88811bee4000 value:0x0
>           ...
>
> Almost all changelogs were suggested by Masami(mhiramat@kernel.org)
> and steve(rostedt@goodmis.org), thank you all so much.
>
> v14:
> - make documentation more readable and fix literal code block by Bagas Sanjaya
>
> v13:
> - remove the 's' type, since the objtrace event doesn't show the value with sign
> - change the [3/4] tag with 'selftests/ftrace' instead of 'trace/objtrace'
> - add 'Documentation:' tag for [4/4]
>
> v12:
> - use the %zu to print the sizeof
>   Reported-by: kernel test robot <lkp@intel.com>
>   Suggested-by: Nathan Chancellor <nathan@kernel.org>
>
> v11:
> - remove useless atomic counting methods for num_traced_obj
> - make array objtrace_fetch_types null terminated
> - add raw_spin_lock_init for obj_data_lock
>
> v10:
> - support ftrace instances
> - use trace_buffer_lock_reserve instead of trace_event_buffer_lock_reserve
> - a lot of cleanup work has been done mainly for event_object_trigger_parse
>
> v9:
> - fix objtrace trigger output was incomplete
> - fix the objtrace trigger was removed when using the existed parameter on
>   event.
> - add testcase for the second fix above.
>
> v8:
> - revert to use per-cpu recursion for the function trace_object_events_call
> - recover the filter when getting the value of the object
> - simplify the implementation for the function get_object_value
> - fix the build error
>
> v7:
> - use fixed-size array for object pool instead of list structure
> - use ftrace_test_recursion_trylock for function trace hook function
> - fix trace_object_ref reference count in the init_trace_object
> - invoke exit_trace_object no matter whether data->ops->free is null
>   in the unregister_object_trigger
> - release private_data of event_trigger_data in the trace_object_trigger_free
> - remove [RFC] tag
>
> v6:
> - change the objtrace trigger syntax.
> - add patchset description
> - add <tracefs>/README
>
> v5:
> - add testcasts
> - add check the field->size
> - add lockless to search object
> - describe the object trace more clearly in Kconfig
>
> v4:
> - please ignore the v4 which is the same as v3
>
> v3:
> - change the objfilter to objtrace
> - add a command to the objfilter syntax
> - change to get the value of the object
> - use trace_find_event_field to find the field instead of using argN
> - get data from @rec in the event trigger callback funciton
>
> v2:
> - adding a "objfilter" trigger to update object
>
> Jeff Xie (4):
>   trace: Add trace any kernel object
>   trace/objtrace: Get the value of the object
>   selftests/ftrace: Add testcases for objtrace
>   Documentation: trace/objtrace: Add documentation for objtrace
>
>  Documentation/trace/events.rst                |  87 +++
>  include/linux/trace_events.h                  |   1 +
>  kernel/trace/Kconfig                          |  10 +
>  kernel/trace/Makefile                         |   1 +
>  kernel/trace/trace.c                          |  11 +
>  kernel/trace/trace.h                          |  21 +
>  kernel/trace/trace_entries.h                  |  18 +
>  kernel/trace/trace_events_trigger.c           |   5 +-
>  kernel/trace/trace_object.c                   | 611 ++++++++++++++++++
>  kernel/trace/trace_output.c                   |  40 ++
>  .../ftrace/test.d/trigger/trigger-objtrace.tc |  41 ++
>  11 files changed, 844 insertions(+), 2 deletions(-)
>  create mode 100644 kernel/trace/trace_object.c
>  create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-objtrace.tc
>
>
> base-commit: 408d26e261b089596c0837e71d2fb4a80ea04ef3
> --
> 2.25.1
>

Thanks,
JeffXie
Re: [PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object
Posted by Steven Rostedt 3 years, 9 months ago 
On Tue, 5 Jul 2022 23:30:46 +0800
Jeff Xie <xiehuan09@gmail.com> wrote:

> Hi Steve,
> 
> I'm curious if you have any comments on this patchset ;-)

Hi Jeff,

I haven't forgotten you. You're still in the queue (which is finally
moving forward). I have a few other patch sets ahead of yours that I
need to go over. Yes, those patches have been waiting longer :-p

-- Steve
Re: [PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object
Posted by Jeff Xie 3 years, 8 months ago 
Hi steve,

I would like to ask whether this patch set may be merged into v6.1  ;-)
The kernel development is indeed very different from what I originally imagined.
I originally thought that objtrace would soon enter the kernel
community, but I know
it may take one to two years, or longer or discarded, I have slowly
come to accept this reality ;-)


On Wed, Jul 6, 2022 at 1:49 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Tue, 5 Jul 2022 23:30:46 +0800
> Jeff Xie <xiehuan09@gmail.com> wrote:
>
> > Hi Steve,
> >
> > I'm curious if you have any comments on this patchset ;-)
>
> Hi Jeff,
>
> I haven't forgotten you. You're still in the queue (which is finally
> moving forward). I have a few other patch sets ahead of yours that I
> need to go over. Yes, those patches have been waiting longer :-p
>
> -- Steve

-- 
Thanks,
JeffXie
Re: [PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object
Posted by Steven Rostedt 3 years, 8 months ago 
On Thu, 18 Aug 2022 23:05:19 +0800
Jeff Xie <xiehuan09@gmail.com> wrote:

> Hi steve,
> 
> I would like to ask whether this patch set may be merged into v6.1  ;-)
> The kernel development is indeed very different from what I originally imagined.
> I originally thought that objtrace would soon enter the kernel
> community, but I know
> it may take one to two years, or longer or discarded, I have slowly
> come to accept this reality ;-)

As, sorry for the late reviews (trying to get through all the other patches
too). I'll see if I can look at it this week.

-- Steve
Re: [PATCH v14 0/4] trace: Introduce objtrace trigger to trace the kernel object
Posted by Jeff Xie 3 years, 8 months ago 
On Thu, Aug 18, 2022 at 11:26 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Thu, 18 Aug 2022 23:05:19 +0800
> Jeff Xie <xiehuan09@gmail.com> wrote:
>
> > Hi steve,
> >
> > I would like to ask whether this patch set may be merged into v6.1  ;-)
> > The kernel development is indeed very different from what I originally imagined.
> > I originally thought that objtrace would soon enter the kernel
> > community, but I know
> > it may take one to two years, or longer or discarded, I have slowly
> > come to accept this reality ;-)
>
> As, sorry for the late reviews (trying to get through all the other patches
> too). I'll see if I can look at it this week.

Thanks so much.

-- 
Thanks,
JeffXie

Patchew 2.1-devel-ea86937

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