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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 54B3CCFD2F6 for ; Tue, 2 Dec 2025 09:37:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To:From: Subject:Message-ID:References:Mime-Version:In-Reply-To:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=NipxkY8EeXODHX4P9Bs9SBlTgKE+SeSFQDJz8FNP0mg=; b=ObWjVRxyqZItfvHPXfyue7AoRl e7/hOE1yA/J5WFEgVuBkcgy96kE+SDuLndZNoOLn9eucw3TM166lm9EP9uGxG2yCt+m4TcKBPx2C9 0dTlAktIsYHDDfAiV5jlnaLvmwJ+U9zVWMlDQgr8qurIYa4RnD41jICps2prPGpEGEElnk19jwLET vwlAQPNLA39VU6UbeH2xVtH0GmYzE882QLS5VYKfeP2Zaq8cDUVtghuKrQLWfMxXX8o9i+WXW/6yM rlkNmBxPMP9ybJ35Tka8KjDYChOkgvkzyYftkwRM96i6DVtFwnfT+QCGCslYPB9BWYhWCLSuuOijc RgC26eTw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQMoX-000000058H2-3P58; Tue, 02 Dec 2025 09:36:53 +0000 Received: from mail-ej1-x649.google.com ([2a00:1450:4864:20::649]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQMoR-0000000583t-0kGZ for linux-arm-kernel@lists.infradead.org; Tue, 02 Dec 2025 09:36:48 +0000 Received: by mail-ej1-x649.google.com with SMTP id a640c23a62f3a-b739a4cf54fso600479266b.3 for ; Tue, 02 Dec 2025 01:36:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1764668205; x=1765273005; darn=lists.infradead.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=NipxkY8EeXODHX4P9Bs9SBlTgKE+SeSFQDJz8FNP0mg=; b=jJlcRQj2Y1D2lFOc/2v2da8SjdGc0NKQkHzCDGU4WLAewzFH7RV0DOUcawkLq4kB5y I7uDiZx35DlYHrot+wMaDMg3AHCCuJ4RN5mwZ5NO1G8I2Ggzm+HSFm4iGHJQh5X9hlMh O4Hy5xa6n+e0G6R9Gk/Ifu7N2Rdk/dV6Qx+HqmZCpbwOTaB/vVCnY1anW7zqyqdEjllL oEQBDCHG+x9d/oVPxj2JiioeZcR6hy7sf1JtdYnrGAao8JmU6IXXMfFSq2UhYuc+GgyD Bwnqvk0ZOT8TuUecty/veLIal8JeHDsO7iDBRz/vKtCpUOfBZibALRQSgxQKbT8e1XNT dtQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764668205; x=1765273005; 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=NipxkY8EeXODHX4P9Bs9SBlTgKE+SeSFQDJz8FNP0mg=; b=QNF4yUvrBHJ0Sqv0kn3vId7HI34DmPZP1r0MEEPcEbNDuNqz8HaqqFJJdOnB5NpOAn W/UEVD/GUzwX/kUwRe6K9c+q6sj7EngDSI4+v8VPtxHsCSKExyz40+wFY1a4WfuGqN4c cKM+uM1LjXxU2ZfxisdYlJcg7YkEW4DNKfKC8Pp/IKPMuwgygIpLwix+02+sc+ej0fKA zWMvTMpwx1nSXuQG8Eu150nKW9StlMiyIUuoCZ2QOvxUtL4ygD80MwCMaaUdWYPaFaJ0 1B8wB3+8c+gWemFs+ocVSBYSlBx2w15NCd5xB6dIWuRuUAwBEPjK1yQlYHrw+Awi5nXY iVpQ== X-Forwarded-Encrypted: i=1; AJvYcCV7r8wrmeG8gklnrhjg9NHAmZ1ZdKwAdHhOTQLksJ1BUZD1VWrVWOOQu75JYjrtsNUi7iRsR+BACjnY2XbWBBvt@lists.infradead.org X-Gm-Message-State: AOJu0Yxn+YL63cZn0x3DOoW5Ua1d2g/VS3e4YvR9DFLcdxyBB0LiW0bF qRNa0NWWYp9tmoE0XJzNgaDbzcOvTAO67MpW5PtlvvKCzioYrAQAN/ZdG7R4jXc/1vcTBTaM2D+ ksChtVXTfY05aVOHLuWhBEA== X-Google-Smtp-Source: AGHT+IGlKbO9GlUAM8Dhc6eQTJzUL7E2crUsrhviZZa4uKHob6cLh56/PpJOXvvcmNdFWTSXz2WmO80ypFE4rVYr X-Received: from ejcub12.prod.google.com ([2002:a17:907:c80c:b0:b72:41e4:7557]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a17:907:2da9:b0:b73:9368:ad44 with SMTP id a640c23a62f3a-b7671700985mr4251756866b.16.1764668204889; Tue, 02 Dec 2025 01:36:44 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:07 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-15-vdonnefort@google.com> Subject: [PATCH v9 14/30] tracing: Add a trace remote module for testing From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251202_013647_292999_AD783971 X-CRM114-Status: GOOD ( 20.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Add a module to help testing the tracefs support for trace remotes. This module: * Use simple_ring_buffer to write into a ring-buffer. * Declare a single "selftest" event that can be triggered from user-space. * Register a "test" trace remote. This is intended to be used by trace remote selftests. Signed-off-by: Vincent Donnefort diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 0c023941a316..aa305be834f9 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -665,6 +665,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode, fsnotify_create(d_inode(dentry->d_parent), dentry); return tracefs_end_creating(dentry); } +EXPORT_SYMBOL_GPL(tracefs_create_file); static struct dentry *__create_dir(const char *name, struct dentry *parent, const struct inode_operations *ops) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 918afcc1fcaf..52131d89993c 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1244,4 +1244,12 @@ config TRACE_REMOTE config SIMPLE_RING_BUFFER bool +config TRACE_REMOTE_TEST + tristate "Test module for remote tracing" + select TRACE_REMOTE + select SIMPLE_RING_BUFFER + help + This trace remote includes a ring-buffer writer implementation using + "simple_ring_buffer". This is solely intending for testing. + endif # FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 03d7d80a9436..53534447e70b 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -112,4 +112,6 @@ obj-$(CONFIG_RV) += rv/ obj-$(CONFIG_TRACE_REMOTE) += trace_remote.o obj-$(CONFIG_SIMPLE_RING_BUFFER) += simple_ring_buffer.o +obj-$(CONFIG_TRACE_REMOTE_TEST) += remote_test.o + libftrace-y := ftrace.o diff --git a/kernel/trace/remote_test.c b/kernel/trace/remote_test.c new file mode 100644 index 000000000000..059127489c99 --- /dev/null +++ b/kernel/trace/remote_test.c @@ -0,0 +1,259 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 - Google LLC + * Author: Vincent Donnefort + */ + +#include +#include +#include +#include +#include + +#define REMOTE_EVENT_INCLUDE_FILE kernel/trace/remote_test_events.h +#include + +static DEFINE_PER_CPU(struct simple_rb_per_cpu *, simple_rbs); +static struct trace_buffer_desc *remote_test_buffer_desc; + +/* + * The trace_remote lock already serializes accesses from the trace_remote_callbacks. + * However write_event can still race with load/unload. + */ +static DEFINE_MUTEX(simple_rbs_lock); + +static int remote_test_load_simple_rb(int cpu, struct ring_buffer_desc *rb_desc) +{ + struct simple_rb_per_cpu *cpu_buffer; + struct simple_buffer_page *bpages; + int ret = -ENOMEM; + + cpu_buffer = kmalloc(sizeof(*cpu_buffer), GFP_KERNEL); + if (!cpu_buffer) + return ret; + + bpages = kmalloc_array(rb_desc->nr_page_va, sizeof(*bpages), GFP_KERNEL); + if (!bpages) + goto err_free_cpu_buffer; + + ret = simple_ring_buffer_init(cpu_buffer, bpages, rb_desc); + if (ret) + goto err_free_bpages; + + scoped_guard(mutex, &simple_rbs_lock) + *per_cpu_ptr(&simple_rbs, cpu) = cpu_buffer; + + return 0; + +err_free_bpages: + kfree(bpages); + +err_free_cpu_buffer: + kfree(cpu_buffer); + + return ret; +} + +static void remote_test_unload_simple_rb(int cpu) +{ + struct simple_rb_per_cpu *cpu_buffer = *per_cpu_ptr(&simple_rbs, cpu); + struct simple_buffer_page *bpages; + + if (!cpu_buffer) + return; + + guard(mutex)(&simple_rbs_lock); + + bpages = cpu_buffer->bpages; + simple_ring_buffer_unload(cpu_buffer); + kfree(bpages); + kfree(cpu_buffer); + *per_cpu_ptr(&simple_rbs, cpu) = NULL; +} + +static struct trace_buffer_desc *remote_test_load(unsigned long size, void *unused) +{ + struct ring_buffer_desc *rb_desc; + struct trace_buffer_desc *desc; + size_t desc_size; + int cpu, ret; + + if (WARN_ON(remote_test_buffer_desc)) + return ERR_PTR(-EINVAL); + + desc_size = trace_buffer_desc_size(size, num_possible_cpus()); + if (desc_size == SIZE_MAX) { + ret = -E2BIG; + goto err_unlock_cpus; + } + + desc = kmalloc(desc_size, GFP_KERNEL); + if (!desc) { + ret = -ENOMEM; + goto err_unlock_cpus; + } + + ret = trace_remote_alloc_buffer(desc, desc_size, size, cpu_possible_mask); + if (ret) + goto err_free_desc; + + for_each_ring_buffer_desc(rb_desc, cpu, desc) { + ret = remote_test_load_simple_rb(rb_desc->cpu, rb_desc); + if (ret) + goto err; + } + + remote_test_buffer_desc = desc; + + return remote_test_buffer_desc; + +err: + for_each_ring_buffer_desc(rb_desc, cpu, remote_test_buffer_desc) + remote_test_unload_simple_rb(rb_desc->cpu); + trace_remote_free_buffer(remote_test_buffer_desc); + +err_free_desc: + kfree(desc); + +err_unlock_cpus: + cpus_read_unlock(); + + return ERR_PTR(ret); +} + +static void remote_test_unload(struct trace_buffer_desc *desc, void *unused) +{ + struct ring_buffer_desc *rb_desc; + int cpu; + + if (WARN_ON(desc != remote_test_buffer_desc)) + return; + + for_each_ring_buffer_desc(rb_desc, cpu, desc) + remote_test_unload_simple_rb(rb_desc->cpu); + + remote_test_buffer_desc = NULL; + trace_remote_free_buffer(desc); + kfree(desc); +} + +static int remote_test_enable_tracing(bool enable, void *unused) +{ + struct ring_buffer_desc *rb_desc; + int cpu; + + if (!remote_test_buffer_desc) + return -ENODEV; + + for_each_ring_buffer_desc(rb_desc, cpu, remote_test_buffer_desc) + WARN_ON(simple_ring_buffer_enable_tracing(*per_cpu_ptr(&simple_rbs, rb_desc->cpu), + enable)); + return 0; +} + +static int remote_test_swap_reader_page(unsigned int cpu, void *unused) +{ + struct simple_rb_per_cpu *cpu_buffer; + + if (cpu >= NR_CPUS) + return -EINVAL; + + cpu_buffer = *per_cpu_ptr(&simple_rbs, cpu); + if (!cpu_buffer) + return -EINVAL; + + return simple_ring_buffer_swap_reader_page(cpu_buffer); +} + +static int remote_test_reset(unsigned int cpu, void *unused) +{ + struct simple_rb_per_cpu *cpu_buffer; + + if (cpu >= NR_CPUS) + return -EINVAL; + + cpu_buffer = *per_cpu_ptr(&simple_rbs, cpu); + if (!cpu_buffer) + return -EINVAL; + + return simple_ring_buffer_reset(cpu_buffer); +} + +static int remote_test_enable_event(unsigned short id, bool enable, void *unused) +{ + if (id != REMOTE_TEST_EVENT_ID) + return -EINVAL; + + /* + * Let's just use the struct remote_event enabled field that is turned on and off by + * trace_remote. This is a bit racy but good enough for a simple test module. + */ + return 0; +} + +static ssize_t +write_event_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *pos) +{ + struct remote_event_format_selftest *evt_test; + struct simple_rb_per_cpu *cpu_buffer; + unsigned long val; + int ret; + + ret = kstrtoul_from_user(ubuf, cnt, 10, &val); + if (ret) + return ret; + + guard(mutex)(&simple_rbs_lock); + + if (!remote_event_selftest.enabled) + return -ENODEV; + + cpu_buffer = *this_cpu_ptr(&simple_rbs); + if (!cpu_buffer) + return -ENODEV; + + evt_test = simple_ring_buffer_reserve(cpu_buffer, + sizeof(struct remote_event_format_selftest), + trace_clock_global()); + if (!evt_test) + return -ENODEV; + + evt_test->hdr.id = REMOTE_TEST_EVENT_ID; + evt_test->id = val; + + simple_ring_buffer_commit(cpu_buffer); + + return cnt; +} + +static const struct file_operations write_event_fops = { + .write = write_event_write, +}; + +static int remote_test_init_tracefs(struct dentry *d, void *unused) +{ + return tracefs_create_file("write_event", 0200, d, NULL, &write_event_fops) ? + 0 : -ENOMEM; +} + +static struct trace_remote_callbacks trace_remote_callbacks = { + .init = remote_test_init_tracefs, + .load_trace_buffer = remote_test_load, + .unload_trace_buffer = remote_test_unload, + .enable_tracing = remote_test_enable_tracing, + .swap_reader_page = remote_test_swap_reader_page, + .reset = remote_test_reset, + .enable_event = remote_test_enable_event, +}; + +static int __init remote_test_init(void) +{ + return trace_remote_register("test", &trace_remote_callbacks, NULL, + &remote_event_selftest, 1); +} + +module_init(remote_test_init); + +MODULE_DESCRIPTION("Test module for the trace remote interface"); +MODULE_AUTHOR("Vincent Donnefort"); +MODULE_LICENSE("GPL"); diff --git a/kernel/trace/remote_test_events.h b/kernel/trace/remote_test_events.h new file mode 100644 index 000000000000..26b93b3406fc --- /dev/null +++ b/kernel/trace/remote_test_events.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#define REMOTE_TEST_EVENT_ID 1 + +REMOTE_EVENT(selftest, REMOTE_TEST_EVENT_ID, + RE_STRUCT( + re_field(u64, id) + ), + RE_PRINTK("id=%llu", __entry->id) +); -- 2.52.0.107.ga0afd4fd5b-goog