Messages in this thread | | | From | Jeff Xie <> | Date | Sat, 11 Dec 2021 00:55:31 +0800 | Subject | Re: [RFC][PATCH v6 0/5] trace: Introduce objtrace trigger to trace the kernel object |
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hi Steve and Masami,
I really don't know what else I can do to enhance this patchset, if this idea is really valuable and can play its role, it may need the help of you or other developers ;-)
On Tue, Nov 30, 2021 at 12:50 AM 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 base the above object. > > find the offset of the bi_size in struct bio: > $ gdb vmlinux > (gdb) p &(((struct bio *)0)->bi_iter.bi_size) > $1 = (unsigned int *) 0x28 > > # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \ > p_bio_add_page_0/trigger > > The best way to use this is that we can set the entrance event and exit > event, for example, the following example is to set the read_papes as > the entrance event, and set the __blk_account_io_start as the exit event. > > # cd /sys/kernel/debug/tracing/ > # echo 0 > ./tracing_on > # echo 'p read_pages' >> ./kprobe_events > # echo 'p __blk_account_io_start' >> ./kprobe_events > # echo 'traceon if comm == "cat"' > ./events/kprobes/p_read_pages_0/trigger > # echo 'traceoff if comm == "cat"' > ./events/kprobes/p___blk_account_io_start_0/trigger > # echo 'p bio_add_page arg1=$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: 50/50 #P:1 > # > # _-----=> irqs-off > # / _----=> need-resched > # | / _---=> hardirq/softirq > # || / _--=> preempt-depth > # ||| / _-=> migrate-disable > # |||| / delay > # TASK-PID CPU# ||||| TIMESTAMP FUNCTION > # | | | ||||| | | > cat-95 [000] ..... 1.412065: _raw_spin_unlock_irqrestore <-event_triggers_call object:0xffff888108af6328 value:0x0 > cat-95 [000] ..... 1.412066: __bio_try_merge_page <-bio_add_page object:0xffff888108af6328 value:0x0 > cat-95 [000] ..... 1.412066: __bio_add_page <-bio_add_page object:0xffff888108af6328 value:0x0 > cat-95 [000] ..... 1.412066: rcu_read_unlock_strict <-xa_load object:0xffff888108af6328 value:0x1000 > cat-95 [000] ..... 1.412066: bio_add_page <-ext4_mpage_readpages object:0xffff888108af6328 value:0x1000 > cat-95 [000] ..... 1.412066: kprobe_ftrace_handler <-ftrace_ops_list_func object:0xffff888108af6328 value:0x1000 > cat-95 [000] ..... 1.412067: get_kprobe <-kprobe_ftrace_handler object:0xffff888108af6328 value:0x1000 > cat-95 [000] ..... 1.412067: __bio_try_merge_page <-bio_add_page object:0xffff888108af6328 value:0x1000 > cat-95 [000] ..... 1.412067: __bio_add_page <-bio_add_page object:0xffff888108af6328 value:0x1000 > cat-95 [000] ..... 1.412067: rcu_read_unlock_strict <-xa_load object:0xffff888108af6328 value:0x2000 > cat-95 [000] ..... 1.412067: bio_add_page <-ext4_mpage_readpages object:0xffff888108af6328 value:0x2000 > cat-95 [000] ..... 1.412067: kprobe_ftrace_handler <-ftrace_ops_list_func object:0xffff888108af6328 value:0x2000 > cat-95 [000] ..... 1.412067: get_kprobe <-kprobe_ftrace_handler object:0xffff888108af6328 value:0x2000 > cat-95 [000] ..... 1.412067: __bio_try_merge_page <-bio_add_page object:0xffff888108af6328 value:0x2000 > cat-95 [000] ..... 1.412068: submit_bio <-ext4_mpage_readpages object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: submit_bio_noacct <-ext4_mpage_readpages object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: __submit_bio <-submit_bio_noacct object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: blk_try_enter_queue <-__submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: rcu_read_unlock_strict <-blk_try_enter_queue object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: rcu_read_unlock_strict <-blk_try_enter_queue object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: submit_bio_checks <-__submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: __cond_resched <-submit_bio_checks object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: rcu_all_qs <-__cond_resched object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412068: should_fail_bio <-submit_bio_checks object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: create_task_io_context <-submit_bio_checks object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: kmem_cache_alloc_node <-create_task_io_context object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: should_failslab <-kmem_cache_alloc_node object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: _raw_spin_lock <-create_task_io_context object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: blk_mq_submit_bio <-__submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: __blk_queue_split <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: bvec_split_segs <-__blk_queue_split object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412069: blk_attempt_plug_merge <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: __blk_mq_sched_bio_merge <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: dd_bio_merge <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: _raw_spin_lock <-dd_bio_merge object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: blk_mq_sched_try_merge <-dd_bio_merge object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: elv_merge <-blk_mq_sched_try_merge object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: elv_rqhash_find <-elv_merge object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: dd_request_merge <-blk_mq_sched_try_merge object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: elv_rb_find <-dd_request_merge object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412070: __blk_mq_alloc_request <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: dd_limit_depth <-__blk_mq_alloc_request object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: blk_mq_get_tag <-__blk_mq_alloc_request object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: __blk_mq_get_tag <-blk_mq_get_tag object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: blk_mq_rq_ctx_init.isra.0 <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: ktime_get <-blk_mq_rq_ctx_init.isra.0 object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: dd_prepare_request <-blk_mq_rq_ctx_init.isra.0 object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: __blk_account_io_start <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: kprobe_ftrace_handler <-ftrace_ops_list_func object:0xffff888108af6328 value:0x3000 > cat-95 [000] ..... 1.412071: get_kprobe <-kprobe_ftrace_handler object:0xffff888108af6328 value:0x3000 > > Jeff Xie (5): > trace: Add trace any kernel object > trace/objtrace: get the value of the object > trace/README: Document objtrace trigger syntax > trace/objtrace: Add testcases for objtrace > trace/objtrace: Add documentation for objtrace > > Documentation/trace/events.rst | 114 +++ > include/linux/trace_events.h | 1 + > kernel/trace/Kconfig | 10 + > kernel/trace/Makefile | 1 + > kernel/trace/trace.c | 3 + > kernel/trace/trace.h | 8 + > kernel/trace/trace_entries.h | 18 + > kernel/trace/trace_events_trigger.c | 1 + > kernel/trace/trace_object.c | 660 ++++++++++++++++++ > kernel/trace/trace_output.c | 40 ++ > .../ftrace/test.d/trigger/trigger-objtrace.tc | 39 ++ > 11 files changed, 895 insertions(+) > create mode 100644 kernel/trace/trace_object.c > create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-objtrace.tc > > -- > 2.25.1 >
Thanks, --- JeffXie
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