Added documentation explaining how to use objtrace trigger to get the value
of the object.
Signed-off-by: Jeff Xie <xiehuan09@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Documentation/trace/events.rst | 83 ++++++++++++++++++++++++++++++++++
1 file changed, 83 insertions(+)
diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index c47f381d0c00..0dc475160133 100644
--- a/Documentation/trace/events.rst
+++ b/Documentation/trace/events.rst
@@ -546,6 +546,89 @@ The following commands are supported:
See Documentation/trace/histogram.rst for details and examples.
+- objtrace
+
+ This command provides a way to get the value of any object, 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
+ ...
+
7. In-kernel trace event API
============================
--
2.25.1On Sun, Jun 26, 2022 at 10:56:04AM +0800, Jeff Xie wrote: > Added documentation explaining how to use objtrace trigger to get the value > of the object. > Write "Add documentation..." instead. > +- objtrace > + > + This command provides a way to get the value of any object, 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. > + Did you mean "the object value can be obtained by only needing to set the objtrace?" > + 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 > + Did you mean "the first parameter (arg1) is the parameter value of function that is passed to kprobe_event, in this case the object base"? > + 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 > + ... > + The output is messy, because for code example and output, literal code blocks aren't used, hence trigger new warnings: Documentation/trace/events.rst:564: WARNING: Inline emphasis start-string without end-string. Documentation/trace/events.rst:564: WARNING: Inline emphasis start-string without end-string. Documentation/trace/events.rst:573: WARNING: Inline emphasis start-string without end-string. Documentation/trace/events.rst:573: WARNING: Inline emphasis start-string without end-string. Documentation/trace/events.rst:602: WARNING: Unexpected indentation. Documentation/trace/events.rst:622: WARNING: Block quote ends without a blank line; unexpected unindent. Documentation/trace/events.rst:630: WARNING: Unexpected indentation. I had to apply the following fixup (with rewording): ---- >8 ---- diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst index 0dc47516013331..c15f1d25d4a071 100644 --- a/Documentation/trace/events.rst +++ b/Documentation/trace/events.rst @@ -549,85 +549,89 @@ The following commands are supported: - objtrace This command provides a way to get the value of any object, The object - can be obtained from the dynamic event(kprobe_event/uprobe_event) or the - static event(tracepoint). + 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. + When using the kprobe event, by only need to set the objtrace (a new + trigger), we can get the value of object that is set by kprobe event. - For example: - For the function bio_add_page(): + For example, for the function bio_add_page(): - int bio_add_page(struct bio *bio, struct page *page, - unsigned int len, unsigned int offset) + .. code-block:: c - 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(), + int bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int offset) - # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events + Firstly, we can set the base of the object as first parameter (arg1) to + to the function: - Secondly, we can get the value dynamically based on above object. + .. code-block:: - find the offset of the bi_size in struct bio: - $ gdb vmlinux - (gdb) p &(((struct bio *)0)->bi_iter.bi_size) - $1 = (unsigned int *) 0x28 + # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events - # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \ - p_bio_add_page_0/trigger + Secondly, we can get the value dynamically based on the object: - # 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 + .. code-block:: - # du -sh /test.txt - 12.0K /test.txt + 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 - # 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 - ... + # 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 + ... 7. In-kernel trace event API ============================ Thanks. -- An old man doll... just what I always wanted! - Clara
Hi, On Mon, Jun 27, 2022 at 10:14 AM Bagas Sanjaya <bagasdotme@gmail.com> wrote: > > On Sun, Jun 26, 2022 at 10:56:04AM +0800, Jeff Xie wrote: > > Added documentation explaining how to use objtrace trigger to get the value > > of the object. > > > > Write "Add documentation..." instead. Thanks, I will change it. > > +- objtrace > > + > > + This command provides a way to get the value of any object, 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. > > + > > Did you mean "the object value can be obtained by only needing to set the > objtrace?" Yes, that's what it means. > > + 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 > > + > > Did you mean "the first parameter (arg1) is the parameter value of function > that is passed to kprobe_event, in this case the object base"? Yes, that's what it means. > > + 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 > > + ... > > + > > The output is messy, because for code example and output, literal code > blocks aren't used, hence trigger new warnings: > > Documentation/trace/events.rst:564: WARNING: Inline emphasis start-string without end-string. > Documentation/trace/events.rst:564: WARNING: Inline emphasis start-string without end-string. > Documentation/trace/events.rst:573: WARNING: Inline emphasis start-string without end-string. > Documentation/trace/events.rst:573: WARNING: Inline emphasis start-string without end-string. > Documentation/trace/events.rst:602: WARNING: Unexpected indentation. > Documentation/trace/events.rst:622: WARNING: Block quote ends without a blank line; unexpected unindent. > Documentation/trace/events.rst:630: WARNING: Unexpected indentation. > > I had to apply the following fixup (with rewording): Thank you so much for your help, It looks better ;-) > ---- >8 ---- > > diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst > index 0dc47516013331..c15f1d25d4a071 100644 > --- a/Documentation/trace/events.rst > +++ b/Documentation/trace/events.rst > @@ -549,85 +549,89 @@ The following commands are supported: > - objtrace > > This command provides a way to get the value of any object, The object > - can be obtained from the dynamic event(kprobe_event/uprobe_event) or the > - static event(tracepoint). > + 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. > + When using the kprobe event, by only need to set the objtrace (a new > + trigger), we can get the value of object that is set by kprobe event. > > - For example: > - For the function bio_add_page(): > + For example, for the function bio_add_page(): > > - int bio_add_page(struct bio *bio, struct page *page, > - unsigned int len, unsigned int offset) > + .. code-block:: c > > - 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(), > + int bio_add_page(struct bio *bio, struct page *page, > + unsigned int len, unsigned int offset) > > - # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events > + Firstly, we can set the base of the object as first parameter (arg1) to > + to the function: > > - Secondly, we can get the value dynamically based on above object. > + .. code-block:: > > - find the offset of the bi_size in struct bio: > - $ gdb vmlinux > - (gdb) p &(((struct bio *)0)->bi_iter.bi_size) > - $1 = (unsigned int *) 0x28 > + # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events > > - # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \ > - p_bio_add_page_0/trigger > + Secondly, we can get the value dynamically based on the object: > > - # 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 > + .. code-block:: > > - # du -sh /test.txt > - 12.0K /test.txt > + 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 > > - # 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 > - ... > + # 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 > + ... > > 7. In-kernel trace event API > ============================ > > > Thanks. > > -- > An old man doll... just what I always wanted! - Clara Thanks, JeffXie
Hi Masami, I would like to ask if I change the document like "Bagas Sanjaya" rewording in the next version. I don't know if I can add your Reviewed-by again, I don't know the rules very well ;-) On Mon, Jun 27, 2022 at 3:45 PM Jeff Xie <xiehuan09@gmail.com> wrote: > > Hi, > > On Mon, Jun 27, 2022 at 10:14 AM Bagas Sanjaya <bagasdotme@gmail.com> wrote: > > > > On Sun, Jun 26, 2022 at 10:56:04AM +0800, Jeff Xie wrote: > > > Added documentation explaining how to use objtrace trigger to get the value > > > of the object. > > > > > > > Write "Add documentation..." instead. > > Thanks, I will change it. > > > > +- objtrace > > > + > > > + This command provides a way to get the value of any object, 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. > > > + > > > > Did you mean "the object value can be obtained by only needing to set the > > objtrace?" > > Yes, that's what it means. > > > > + 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 > > > + > > > > Did you mean "the first parameter (arg1) is the parameter value of function > > that is passed to kprobe_event, in this case the object base"? > > Yes, that's what it means. > > > > + 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 > > > + ... > > > + > > > > The output is messy, because for code example and output, literal code > > blocks aren't used, hence trigger new warnings: > > > > Documentation/trace/events.rst:564: WARNING: Inline emphasis start-string without end-string. > > Documentation/trace/events.rst:564: WARNING: Inline emphasis start-string without end-string. > > Documentation/trace/events.rst:573: WARNING: Inline emphasis start-string without end-string. > > Documentation/trace/events.rst:573: WARNING: Inline emphasis start-string without end-string. > > Documentation/trace/events.rst:602: WARNING: Unexpected indentation. > > Documentation/trace/events.rst:622: WARNING: Block quote ends without a blank line; unexpected unindent. > > Documentation/trace/events.rst:630: WARNING: Unexpected indentation. > > > > I had to apply the following fixup (with rewording): > > Thank you so much for your help, It looks better ;-) > > > ---- >8 ---- > > > > diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst > > index 0dc47516013331..c15f1d25d4a071 100644 > > --- a/Documentation/trace/events.rst > > +++ b/Documentation/trace/events.rst > > @@ -549,85 +549,89 @@ The following commands are supported: > > - objtrace > > > > This command provides a way to get the value of any object, The object > > - can be obtained from the dynamic event(kprobe_event/uprobe_event) or the > > - static event(tracepoint). > > + 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. > > + When using the kprobe event, by only need to set the objtrace (a new > > + trigger), we can get the value of object that is set by kprobe event. > > > > - For example: > > - For the function bio_add_page(): > > + For example, for the function bio_add_page(): > > > > - int bio_add_page(struct bio *bio, struct page *page, > > - unsigned int len, unsigned int offset) > > + .. code-block:: c > > > > - 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(), > > + int bio_add_page(struct bio *bio, struct page *page, > > + unsigned int len, unsigned int offset) > > > > - # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events > > + Firstly, we can set the base of the object as first parameter (arg1) to > > + to the function: > > > > - Secondly, we can get the value dynamically based on above object. > > + .. code-block:: > > > > - find the offset of the bi_size in struct bio: > > - $ gdb vmlinux > > - (gdb) p &(((struct bio *)0)->bi_iter.bi_size) > > - $1 = (unsigned int *) 0x28 > > + # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events > > > > - # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \ > > - p_bio_add_page_0/trigger > > + Secondly, we can get the value dynamically based on the object: > > > > - # 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 > > + .. code-block:: > > > > - # du -sh /test.txt > > - 12.0K /test.txt > > + 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 > > > > - # 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 > > - ... > > + # 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 > > + ... > > > > 7. In-kernel trace event API > > ============================ > > > > > > Thanks. > > > > -- > > An old man doll... just what I always wanted! - Clara > > Thanks, > JeffXie Thanks, JeffXie
On 6/28/22 08:37, Jeff Xie wrote: > Hi Masami, > > I would like to ask if I change the document like "Bagas Sanjaya" > rewording in the next version. > I don't know if I can add your Reviewed-by again, I don't know the > rules very well ;-) > In the next version roll, just mention the feedback in the patch changelog (but not in the patch message as would appear on git log). -- An old man doll... just what I always wanted! - Clara
On Tue, Jun 28, 2022 at 10:31 AM Bagas Sanjaya <bagasdotme@gmail.com> wrote: > > On 6/28/22 08:37, Jeff Xie wrote: > > Hi Masami, > > > > I would like to ask if I change the document like "Bagas Sanjaya" > > rewording in the next version. > > I don't know if I can add your Reviewed-by again, I don't know the > > rules very well ;-) > > > > In the next version roll, just mention the feedback in the patch > changelog (but not in the patch message as would appear on git log). Okay, thank you for your reply ;-) > -- > An old man doll... just what I always wanted! - Clara Thanks, JeffXie
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