From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24D71C433F5 for ; Sat, 13 Nov 2021 12:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07C3F60F0F for ; Sat, 13 Nov 2021 12:07:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235906AbhKMMJx (ORCPT ); Sat, 13 Nov 2021 07:09:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235891AbhKMMJu (ORCPT ); Sat, 13 Nov 2021 07:09:50 -0500 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D4EBC061766 for ; Sat, 13 Nov 2021 04:06:58 -0800 (PST) Received: by mail-pl1-x629.google.com with SMTP id u11so10597217plf.3 for ; Sat, 13 Nov 2021 04:06:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=5Ig/hC1JsR79FU+NK1svNvTely2SBTzXY1ZoF28hg1Q=; b=J1o5t45XCUIfqB4nnQBbue9t9vnO3jqkz8u2yHceDOcvJgx4bRHkVbHNT5ZuhIU303 dxVwNsSbviv0PbK4UqXldIicnOT6kcmux2Vs5sInqO54P8B0y8//1FvzFE2j9F8ytxJ6 MWtWRkBO6spXHEMXaNCQx0pN/cK9iCSDHV/sRDt2SPpGTFn6aYuf5rUhwv0E4flqeBzb Mvq6XYVCQiPD0veceamJUtKlOzwSjq1r2wtgJMspL6fT57f6VHnI7YrxeR+/bifvNNk9 h7AAtp14kg0natFE++CfYiqXxPEC7nX/bC0XEVr4QYO+3i7DsoZvgX2bP9WrGgrwnHEm Fxvg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5Ig/hC1JsR79FU+NK1svNvTely2SBTzXY1ZoF28hg1Q=; b=xEXMfUcWK+RkekWzFVq9wclw8ZhTRHFYkGnJAKSnTrKnGNG5G6xub37sPXiogo5rTG g/WVAkV/SplkVmX4kzrh+GhshnUga9GO9N0IbDevrDeJbt50VejvXVvdt2RwKitcb+OR ilxuhxr5E4E74aQOHJY17u8rZHWSQx8aBNT/TyojDXKyS6oVvLjCPpLfuV/xFD66MNNi XzPPoD08Lmys9MDFFsekXFBmRDN3LTC9EyJskVQTbI6HPTLhhDjpCtfHUlCBLmHRJMSX KeW7dJUvBj8gYfpJJjmm3+z3P6cYPCSdkOQEDG8YxFCganHjLCniuRuokImHqpiBBezB fS/A== X-Gm-Message-State: AOAM531Y/ovbLygGB6AcPgXnJqPzPs0Lgk64BVBoUNGrZl+FluT696mQ PO+Kw8H1xK45UTKSRjmbsfM3jx5n3lk= X-Google-Smtp-Source: ABdhPJy8TwNbeUdRtnIyX32RmU0DpDIj1MmDFm2gpe2EW2SN/u/s9e50+FC51FS+kOJ1vQuiLFsIvQ== X-Received: by 2002:a17:902:b588:b0:143:b732:834 with SMTP id a8-20020a170902b58800b00143b7320834mr2715858pls.22.1636805217648; Sat, 13 Nov 2021 04:06:57 -0800 (PST) Received: from localhost.localdomain (li567-56.members.linode.com. [192.155.81.56]) by smtp.gmail.com with ESMTPSA id z22sm9290403pfe.93.2021.11.13.04.06.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 13 Nov 2021 04:06:57 -0800 (PST) From: Jeff Xie To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mingo@redhat.com, zanussi@kernel.org, linux-kernel@vger.kernel.org, Jeff Xie Subject: [RFC][PATCH v5 4/4] trace/objtrace: Add documentation for objtrace trigger Date: Sat, 13 Nov 2021 20:06:32 +0800 Message-Id: <20211113120632.94754-4-xiehuan09@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211113120632.94754-1-xiehuan09@gmail.com> References: <20211113120632.94754-1-xiehuan09@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Jeff Xie --- Documentation/trace/events.rst | 114 +++++++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst index 8ddb9b09451c..d1ccb9ac5e7c 100644 --- a/Documentation/trace/events.rst +++ b/Documentation/trace/events.rst @@ -527,6 +527,120 @@ 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 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) + $1 = (unsigned int *) 0x28 + + # echo 'objtrace:0x28(arg1):u32:1 if comm == "cat"' > ./events/kprobes/ \ + p_bio_add_page_0/trigger + + The best way to use this is that we can set the entrance event and exit + event, for example, the following example is to set the read_papes as + the entrance event, and set the blk_account_io_start as the exit event. + + # cd /sys/kernel/debug/tracing/ + # echo 0 > ./tracing_on + # echo 'p read_pages' >> ./kprobe_events + # echo 'p blk_account_io_start' >> ./kprobe_events + # echo 'traceon if comm == "cat"' > ./events/kprobes/p_read_pages_0/trigger + # echo 'traceoff if comm == "cat"' > ./events/kprobes/p_blk_account_io_start_0/trigger + # echo 'p bio_add_page arg1=$arg1' >> ./kprobe_events + # echo 'objtrace:0x28(arg1):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 + 7. In-kernel trace event API ============================ -- 2.25.1