From patchwork Mon Dec 5 21:00:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 2630 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:f944:0:0:0:0:0 with SMTP id q4csp2470134wrr; Mon, 5 Dec 2022 13:01:02 -0800 (PST) X-Google-Smtp-Source: AA0mqf4RU6b+tUj7Enq1Wl47I5teK9PtphA2LbC6d5cp0LnBXRflD/+OvOw90IZb+pryHzlIbdtr X-Received: by 2002:a05:6402:e8c:b0:468:89dd:aa0b with SMTP id h12-20020a0564020e8c00b0046889ddaa0bmr76595607eda.258.1670274062071; Mon, 05 Dec 2022 13:01:02 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1670274062; cv=none; d=google.com; s=arc-20160816; b=Yna0AEgTqq75eiid9qTcAiNU0ciUmTHxuplc5lkPApz2QjTUKuol6U2UX2X1P6Ndzq k8m02YlKpacbIoWtwgSm+e1zcHDxEzpu+i4cdcqa6JWh8w4es6kPTBD1S55qq7EhIM3A Ozxo+1ROVB979t/XjfuJPKvpAOKSgyKoJQCsVZ5RGLPrdPVFsy+IoevbpgLxAAAObFTH 6dgl3NAeM3+sL0zRxE4QvADimRHiMJqBn0lhgxqnD1lEzdpGr50HxRZKwP5mjS7GYSj2 yif39JyBKHi0lHDVWaNx81smxeP2HcF53JGRvydZR4NV56LxbB1CWxumfbruQmms/k2e T0rA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature:dkim-filter; bh=wgvbYUS3974Re2/jAlcy5VeGB4akqj2Nyqve6yU4fvg=; b=0yPrPHyGfCCBhVDCIIPbCvY06DZAeOwL1ZP57p5ZS0PWO9YtGgouejm3W1zYNvBWl2 ceAYaEVJBa1K+AU4QRCFlfJvh90t4EOrf90Yw6++u8WIGbzQcfK1QVbw3Xh4ihY7ZPVD n0ZdWEDtFG08HX27tjQ+CRnvWIVacvkYuFfT+tn25W2rCHF7/TlScofmuqfa7T90wNbC jZTHHLG/bUmU7bTMbhDqJjdnZhY5DZ6ng+0JNvt1xqHSatlwdKvBt111diKbHEXCM2gx 0nnRXS+a5+g2cZLgVMKM1bOZGwi5GiK4EOj+mES/ACiNWaOh4kxnypp6AHrPRnPDySV2 9zVQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linux.microsoft.com header.s=default header.b="X7gb/uTo"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.microsoft.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id nd22-20020a170907629600b00787803711f9si8717744ejc.353.2022.12.05.13.00.39; Mon, 05 Dec 2022 13:01:02 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linux.microsoft.com header.s=default header.b="X7gb/uTo"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.microsoft.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233534AbiLEVA0 (ORCPT + 99 others); Mon, 5 Dec 2022 16:00:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231990AbiLEVAY (ORCPT ); Mon, 5 Dec 2022 16:00:24 -0500 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 697872528D; Mon, 5 Dec 2022 13:00:23 -0800 (PST) Received: from W11-BEAU-MD.localdomain (unknown [76.135.50.127]) by linux.microsoft.com (Postfix) with ESMTPSA id C775520B6C40; Mon, 5 Dec 2022 13:00:22 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C775520B6C40 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1670274023; bh=wgvbYUS3974Re2/jAlcy5VeGB4akqj2Nyqve6yU4fvg=; h=From:To:Cc:Subject:Date:From; b=X7gb/uToNGvSo5SrPKsdvrCaI/6x+VOatK+OnsXZffX9yP7DPB+jgyB0iN3xanpny ooR3pUjoRQxJFL8g2Sl1cArFdkYAb9OWBQjdIlM3v4N7dlsGyKOEriBt1R45EMkxdg EFKlt6EK00XSmA1rtjKU6voqr8wQksboDP27oHyA= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, dcook@linux.microsoft.com, alanau@linux.microsoft.com, brauner@kernel.org, akpm@linux-foundation.org Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 00/11] tracing/user_events: Remote write ABI Date: Mon, 5 Dec 2022 13:00:06 -0800 Message-Id: <20221205210017.23440-1-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Spam-Status: No, score=-19.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_MED, SPF_HELO_PASS,SPF_PASS,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1751409295162026107?= X-GMAIL-MSGID: =?utf-8?q?1751409295162026107?= As part of the discussions for user_events aligned with user space tracers, it was determined that user programs should register a aligned value to set or clear a bit when an event becomes enabled. Currently a shared page is being used that requires mmap(). Remove the shared page implementation and move to a user registered address implementation. In this new model during the event registration from user programs 3 new values are specified. The first is the address to update when the event is either enabled or disabled. The second is the bit to set/clear to reflect the event being enabled. The third is the size of the value at the specified address. This allows for a local 32/64-bit value in user programs to support both kernel and user tracers. As an example, setting bit 31 for kernel tracers when the event becomes enabled allows for user tracers to use the other bits for ref counts or other flags. The kernel side updates the bit atomically, user programs need to also update these values atomically. User provided addresses must be aligned on a natural boundary, this allows for single page checking and prevents odd behaviors such as a enable value straddling 2 pages instead of a single page. When page faults are encountered they are done asyncly via a workqueue. If the page faults back in, the write update is attempted again. If the page cannot fault-in, then we log and wait until the next time the event is enabled/disabled. This is to prevent possible infinite loops resulting from bad user processes unmapping or changing protection values after registering the address. Change history V5: GFP_NOWAIT is still needed in user_event_enabler_dup(), due to rcu lock. V4: Rebase to 6.1-rc7. Moved user_events_fork() out of task signal lock and dropped use of GFP_NOWAIT. All allocations are now GFP_KERNEL or GFP_KERNEL_ACCOUNT. Added boot parameter user_events_max= to limit global events. Added sysctl value kernel.user_events_max to limit global events. Added cgroup tracking of memory allocated for events. V3: Rebase to 6.1-rc6. Removed RFC tag on series. Updated documentation to reflect ABI changes. Added self-test for ABI specific clone/fork cases. Moved user_event_mm removal into do_exit() to ensure RSS task accounting is done properly in async fault paths. Also lets us remove the delayed mmdrop(), saving memory in each user_event_mm struct. Fixed timing window where task exits, but write could be in-progress. During exit we now take mmap_write_lock to ensure we drain writes. V2: Rebase to 6.1-rc5. Added various comments based on feedback. Added enable_size to register struct, allows 32/64 bit addresses as long as the enable_bit fits and the address is naturally aligned. Changed user_event_enabler_write to accept a new flag indicating if a fault fixup should be done or not. This allows user_event_enabler_create to return back failures to the user ioctl reg call and retry to fault in data. Added tracking fork/exec/exit of tasks to have the user_event_mm lifetime tied more to the task than the file. This came with extra requirements around when you can lock, such as softirq cases, as well as a RCU pattern to ensure fork/exec/exit take minimal lock times. Changed enablers to use a single word-aligned value for saving the bit to set and any flags, such as faulting asyncly or being freed. This was required to ensure atomic bit set/test for fork cases where taking the event_mutex is not a good scalability decision. Added unregister IOCTL, since file lifetime no longer limits the enable time for any events (the mm does). Updated sample code to reflect the new remote write based ABI. Updated self-test code to reflect the new remote write based ABI. Beau Belgrave (11): tracing/user_events: Split header into uapi and kernel tracing/user_events: Track fork/exec/exit for mm lifetime tracing/user_events: Use remote writes for event enablement tracing/user_events: Fixup enable faults asyncly tracing/user_events: Add ioctl for disabling addresses tracing/user_events: Update self-tests to write ABI tracing/user_events: Add ABI self-test tracing/user_events: Use write ABI in example tracing/user_events: Update documentation for ABI tracing/user_events: Charge event allocs to cgroups tracing/user_events: Limit global user_event count Documentation/trace/user_events.rst | 172 ++-- fs/exec.c | 2 + include/linux/sched.h | 5 + include/linux/user_events.h | 99 +- include/uapi/linux/user_events.h | 81 ++ kernel/exit.c | 2 + kernel/fork.c | 2 + kernel/trace/Kconfig | 5 +- kernel/trace/trace_events_user.c | 847 +++++++++++++++--- samples/user_events/example.c | 47 +- tools/testing/selftests/user_events/Makefile | 2 +- .../testing/selftests/user_events/abi_test.c | 228 +++++ .../testing/selftests/user_events/dyn_test.c | 2 +- .../selftests/user_events/ftrace_test.c | 162 ++-- .../testing/selftests/user_events/perf_test.c | 39 +- 15 files changed, 1296 insertions(+), 399 deletions(-) create mode 100644 include/uapi/linux/user_events.h create mode 100644 tools/testing/selftests/user_events/abi_test.c base-commit: b7b275e60bcd5f89771e865a8239325f86d9927d