From patchwork Mon Jan 29 14:28:00 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Donnefort X-Patchwork-Id: 193508 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:7301:2087:b0:106:209c:c626 with SMTP id gs7csp601921dyb; Mon, 29 Jan 2024 06:29:42 -0800 (PST) X-Google-Smtp-Source: AGHT+IHMLAEck8plZVAc/voo2GdMCEZ3ecaqEQd4zaGRAc8NeFVDvNOxlcKGT+EDS5hiTcdXEDNg X-Received: by 2002:a2e:3618:0:b0:2cc:dc54:871e with SMTP id d24-20020a2e3618000000b002ccdc54871emr3645297lja.24.1706538581971; Mon, 29 Jan 2024 06:29:41 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1706538581; cv=pass; d=google.com; s=arc-20160816; b=HfhmoKX2mvfBRC4u4hwq0ZQ9UXhVUQixi2fKp5+25BTIDuti4qPi/PnRArpeGNrp6N gTkMJ1pmpEL2VNnEdpH0ptcNkr87X4+sXnL/JIA3qe3NQByxiDbFYsJWfeKs5g6PPGML okM8jJ8MtTxQn20pnAhiLgu2XsUFcR6J+2ofDRkkysO7hxt/+2FPqcIqSN7zjqSWJ26P aN0Veuj68pDaUEbb+dMdWo0jQSEQvFkC+XJmRQ8W86yHwMpHJ7W0OAlj1iDaS70g7DDQ 5ltuQz+2MG7eTjWpmVTLx8iIktWbDVntuv1xgjAr2TfQWhoVAAOWzeoXR974P7oDNHnG kv5Q== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:from:subject:message-id:references:mime-version :list-unsubscribe:list-subscribe:list-id:precedence:in-reply-to:date :dkim-signature; bh=m4qRXjTQVo0RcEeMrfJKcOpRJsj7Drr77yBnbAPk5yc=; fh=Osewoyidmyt6GUNpr1HkxMO6OLm/aX24FkE9kqTXAtA=; b=GhLdA/VNXOyvcf18xI2ae+WW3wZ04HxXg6RhlaS/TJmmM1sdL7lgSk9RxS9O8H9ywn 8YZpElA2EFRNYEJ8hCvIEQF7uBDy42troi5PNcNLmE2hp42w1Kvd9wQIBQE4o5N0ODuJ pXRbvgJXhSRiGDzxiAmQv47Z3tMzLuAK+nbtIhafhK1yItC6Vec+aNv/la2YkAG5DLis 9MAWljwxcXYPBPPEHBfGuLypfN46nWDdrzZ/KwmV/6Bzv0yQNianw2o4uyY8mbYWMBEB m6BQblEvfYZcrDEkjA8Q2Tc8ybGs5dPVpaFrKS//RtouTW1FzZ0pL3io4DPf7XVSZ6Zt hMAA== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=BdUSRWbc; arc=pass (i=1 spf=pass spfdomain=flex--vdonnefort.bounces.google.com dkim=pass dkdomain=google.com dmarc=pass fromdomain=google.com); spf=pass (google.com: domain of linux-kernel+bounces-42902-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) smtp.mailfrom="linux-kernel+bounces-42902-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from am.mirrors.kernel.org (am.mirrors.kernel.org. [147.75.80.249]) by mx.google.com with ESMTPS id ek22-20020a056402371600b0055cd006bbc6si3555381edb.300.2024.01.29.06.29.41 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jan 2024 06:29:41 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-42902-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=BdUSRWbc; arc=pass (i=1 spf=pass spfdomain=flex--vdonnefort.bounces.google.com dkim=pass dkdomain=google.com dmarc=pass fromdomain=google.com); spf=pass (google.com: domain of linux-kernel+bounces-42902-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) smtp.mailfrom="linux-kernel+bounces-42902-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id 690761F26561 for ; Mon, 29 Jan 2024 14:29:41 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C077B12C559; Mon, 29 Jan 2024 14:28:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="BdUSRWbc" Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 204A786AF9 for ; Mon, 29 Jan 2024 14:28:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706538503; cv=none; b=ULVk44JnBi+zgfxbUjs9nAcBTUP7eRIAahqE+DAl/tY9ND9woPqDGd542zdrz9NX0Xp2tiodGelrQnOxYEoNJaS+XCpkDSfMdMBDtfcMAqFKXybrig8TD5K3I/Ut2N57EQg1n7PGQM5R93yGP7/+jB4rr1XI/l1/VoFClfuBvhU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706538503; c=relaxed/simple; bh=8l3Xro9CGBurtt6Wge/Qc8D/2BsLWQZglREppaxWwFc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=C8TzQgLkDjdO5cMsfgRAS4xrcxytOLU17s7n0bh9fnowWR52C54/1qaP8aAUiN+huM62x777azqVcYcdlcIWEC5JilWOqAd3PeeYfwAQ/qGV4cjv0rLhufrkQ5FopXpm0XCG1oHbQZdoMK9mNtyxAcV/Ptu2JyRWJkzbe0Gw2Gw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=BdUSRWbc; arc=none smtp.client-ip=209.85.221.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Received: by mail-wr1-f73.google.com with SMTP id ffacd0b85a97d-33aebf85ce9so525244f8f.1 for ; Mon, 29 Jan 2024 06:28:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706538499; x=1707143299; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=m4qRXjTQVo0RcEeMrfJKcOpRJsj7Drr77yBnbAPk5yc=; b=BdUSRWbcguyJDEsJCjKtITa7EZ0+0gaiBxw3y5oNWclEieaTEjUtts/TYvOcDBCjjZ kvjcIVGpBgq+qlaq9K6YaJO8Vl07/e+UMuIA/xFgfiVsJxo6qu6ablaF9QzB6LSWqggZ U/d2zo3V25w/N1xFIwb1R8AS6mdSLqE4caZnla/8xvSsKvAAHg0mC3coMUOCn5Ynzk6K eesNzHgJIak9Taco3Ou9GGokK+jZAlOoxYguzdot5HiWBu7CK/MwnPoZbUddB6mUtn9B 5lH+9LcqNFnclJf7Kb/y0mGX2hWiFvwGeBGm/OOiLJcYU/YD+Gl7R3+8o0x0LUPTYJ8F DkAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706538499; x=1707143299; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=m4qRXjTQVo0RcEeMrfJKcOpRJsj7Drr77yBnbAPk5yc=; b=gdSsdXJLy6ooFNLj9PkXxNMlSnnDXCB1DwAqwI5jB+uovkeLID/pUkw4O4iz3vGpI2 4Vw5ubd3QSQPEPKODu+fL535vU00tkJuEgDh2WeuiykYN9hLOiYnOUE/PcejV346zgly XY/BC9OLrs1IP6K8baeyiB9nnGdfs1q8oXuo91KclVXaHq0pG5rWZ1j2UiB5FvIohi3u L5qqMuDoGfum92eoG/vCMdtiXVhAjekvY7IQluFq4M5a9Tq+szsTdPC0moE5y8pY7BTK QBhuEbLfGc1oWaxA/XH64eVIJ9MXMpRCxCvIpHXy19nu+FRPhAed2/T2lGCc3y7BjWtz ZuAA== X-Gm-Message-State: AOJu0YzWHWBLbSGyUtezR3yTPfQTnaOD1hqbuL1BrTjpRwYToiSkzmSZ tk0ZTz+LGNf8Qyz6Lh/OuUdGgTf6MrUiQw6Ev0DqjEMy9CuwsUGnyiGM1r1nR4XgX601eQxzheM gfcvFaDhSHOsjOC3k5g== X-Received: from vdonnefort.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:2eea]) (user=vdonnefort job=sendgmr) by 2002:a05:6000:1f0e:b0:33a:ed58:9c24 with SMTP id bv14-20020a0560001f0e00b0033aed589c24mr5183wrb.10.1706538499562; Mon, 29 Jan 2024 06:28:19 -0800 (PST) Date: Mon, 29 Jan 2024 14:28:00 +0000 In-Reply-To: <20240129142802.2145305-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240129142802.2145305-1-vdonnefort@google.com> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240129142802.2145305-5-vdonnefort@google.com> Subject: [PATCH v13 4/6] tracing: Allow user-space mapping of the ring-buffer From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, Vincent Donnefort X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1789435399729255848 X-GMAIL-MSGID: 1789435399729255848 Currently, user-space extracts data from the ring-buffer via splice, which is handy for storage or network sharing. However, due to splice limitations, it is imposible to do real-time analysis without a copy. A solution for that problem is to let the user-space map the ring-buffer directly. The mapping is exposed via the per-CPU file trace_pipe_raw. The first element of the mapping is the meta-page. It is followed by each subbuffer constituting the ring-buffer, ordered by their unique page ID: * Meta-page -- include/uapi/linux/trace_mmap.h for a description * Subbuf ID 0 * Subbuf ID 1 ... It is therefore easy to translate a subbuf ID into an offset in the mapping: reader_id = meta->reader->id; reader_offset = meta->meta_page_size + reader_id * meta->subbuf_size; When new data is available, the mapper must call a newly introduced ioctl: TRACE_MMAP_IOCTL_GET_READER. This will update the Meta-page reader ID to point to the next reader containing unread data. Signed-off-by: Vincent Donnefort diff --git a/include/uapi/linux/trace_mmap.h b/include/uapi/linux/trace_mmap.h index d4bb67430719..47194c51a4ac 100644 --- a/include/uapi/linux/trace_mmap.h +++ b/include/uapi/linux/trace_mmap.h @@ -40,4 +40,6 @@ struct trace_buffer_meta { __u64 Reserved2; }; +#define TRACE_MMAP_IOCTL_GET_READER _IO('T', 0x1) + #endif /* _TRACE_MMAP_H_ */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b6a0e506b3f9..b570f4519d87 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1175,6 +1175,12 @@ static void tracing_snapshot_instance_cond(struct trace_array *tr, return; } + if (tr->mapped) { + trace_array_puts(tr, "*** BUFFER MEMORY MAPPED ***\n"); + trace_array_puts(tr, "*** Can not use snapshot (sorry) ***\n"); + return; + } + local_irq_save(flags); update_max_tr(tr, current, smp_processor_id(), cond_data); local_irq_restore(flags); @@ -1309,6 +1315,9 @@ static int tracing_arm_snapshot_locked(struct trace_array *tr) if (tr->snapshot == UINT_MAX) return -EBUSY; + if (tr->mapped) + return -EBUSY; + ret = tracing_alloc_snapshot_instance(tr); if (ret) return ret; @@ -6534,7 +6543,7 @@ static void tracing_set_nop(struct trace_array *tr) { if (tr->current_trace == &nop_trace) return; - + tr->current_trace->enabled--; if (tr->current_trace->reset) @@ -8653,15 +8662,31 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, return ret; } -/* An ioctl call with cmd 0 to the ring buffer file will wake up all waiters */ static long tracing_buffers_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct ftrace_buffer_info *info = file->private_data; struct trace_iterator *iter = &info->iter; + int err; - if (cmd) - return -ENOIOCTLCMD; + if (cmd == TRACE_MMAP_IOCTL_GET_READER) { + if (!(file->f_flags & O_NONBLOCK)) { + err = ring_buffer_wait(iter->array_buffer->buffer, + iter->cpu_file, + iter->tr->buffer_percent); + if (err) + return err; + } + + return ring_buffer_map_get_reader(iter->array_buffer->buffer, + iter->cpu_file); + } else if (cmd) { + return -ENOTTY; + } + /* + * An ioctl call with cmd 0 to the ring buffer file will wake up all + * waiters + */ mutex_lock(&trace_types_lock); iter->wait_index++; @@ -8674,6 +8699,90 @@ static long tracing_buffers_ioctl(struct file *file, unsigned int cmd, unsigned return 0; } +static vm_fault_t tracing_buffers_mmap_fault(struct vm_fault *vmf) +{ + struct ftrace_buffer_info *info = vmf->vma->vm_file->private_data; + struct trace_iterator *iter = &info->iter; + vm_fault_t ret = VM_FAULT_SIGBUS; + struct page *page; + + page = ring_buffer_map_fault(iter->array_buffer->buffer, iter->cpu_file, + vmf->pgoff); + if (!page) + return ret; + + get_page(page); + vmf->page = page; + vmf->page->mapping = vmf->vma->vm_file->f_mapping; + vmf->page->index = vmf->pgoff; + + return 0; +} + +static void tracing_buffers_mmap_close(struct vm_area_struct *vma) +{ + struct ftrace_buffer_info *info = vma->vm_file->private_data; + struct trace_iterator *iter = &info->iter; + + ring_buffer_unmap(iter->array_buffer->buffer, iter->cpu_file); + +#ifdef CONFIG_TRACER_MAX_TRACE + mutex_lock(&trace_types_lock); + if (!WARN_ON(!iter->tr->mapped)) + iter->tr->mapped--; + mutex_unlock(&trace_types_lock); +#endif +} + +static void tracing_buffers_mmap_open(struct vm_area_struct *vma) +{ + struct ftrace_buffer_info *info = vma->vm_file->private_data; + struct trace_iterator *iter = &info->iter; + + WARN_ON(ring_buffer_map(iter->array_buffer->buffer, iter->cpu_file)); +} + +static const struct vm_operations_struct tracing_buffers_vmops = { + .open = tracing_buffers_mmap_open, + .close = tracing_buffers_mmap_close, + .fault = tracing_buffers_mmap_fault, +}; + +static int tracing_buffers_mmap(struct file *filp, struct vm_area_struct *vma) +{ + struct ftrace_buffer_info *info = filp->private_data; + struct trace_iterator *iter = &info->iter; + int ret = 0; + + if (vma->vm_flags & VM_WRITE) + return -EPERM; + + vm_flags_mod(vma, VM_DONTCOPY | VM_DONTDUMP, VM_MAYWRITE); + vma->vm_ops = &tracing_buffers_vmops; + +#ifdef CONFIG_TRACER_MAX_TRACE + mutex_lock(&trace_types_lock); + if (iter->tr->snapshot || iter->tr->mapped == INT_MAX) { + ret = -EBUSY; + goto unlock; + } + + /* Wait for update_max_tr() to observe iter->tr->mapped */ + if (!iter->tr->mapped++) + synchronize_rcu(); +#endif + + ret = ring_buffer_map(iter->array_buffer->buffer, iter->cpu_file); + +#ifdef CONFIG_TRACER_MAX_TRACE + if (ret) + iter->tr->mapped--; +unlock: + mutex_unlock(&trace_types_lock); +#endif + return ret; +} + static const struct file_operations tracing_buffers_fops = { .open = tracing_buffers_open, .read = tracing_buffers_read, @@ -8682,6 +8791,7 @@ static const struct file_operations tracing_buffers_fops = { .splice_read = tracing_buffers_splice_read, .unlocked_ioctl = tracing_buffers_ioctl, .llseek = no_llseek, + .mmap = tracing_buffers_mmap, }; static ssize_t diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 3aa06bd5e48d..25ec246d5f1e 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -335,6 +335,7 @@ struct trace_array { struct array_buffer max_buffer; bool allocated_snapshot; unsigned int snapshot; + int mapped; #endif #ifdef CONFIG_TRACER_MAX_TRACE unsigned long max_latency;