From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (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 A5BB7346A0D for ; Thu, 19 Feb 2026 15:03:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771513418; cv=none; b=lTbewSXXgVxZ2Wh21tzCx+X8FZ/8qhv7/B7xLrI6kgK+GO4U370R9qGYc+irZP/gfofagqNxNeGNnICG2xAWLIE61VXsnmaj6Tdtke5xYjWAev+AGH46XvxxQXST/wl1BFY4UgitcB3n98Wtk6twIbIil6I5qHfrbBhZotimkHc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771513418; c=relaxed/simple; bh=HiMzk0YkJOcTqiGkVMJtD5112U44kDSTtCwI2QQPY4w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=RaA/AUCw0y+3AS396y816/0A77WTndTSDM0VJafbB8Q92xBpcPU7mU+kRyqlhMXAaD8GYfRDYSIg4yBSQumzqIhL4L5TkMTvAo4SXzjuFrJOdJA6Sk10S1Yr7rBubJqI+INyPD3fqOkCLtMY15w+co0K+7a8eIbHoWtpklhJ6uQ= 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=YYECaj5W; arc=none smtp.client-ip=209.85.128.74 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="YYECaj5W" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-4806b12ad3fso8031805e9.0 for ; Thu, 19 Feb 2026 07:03:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1771513415; x=1772118215; 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=TUoZFO6QDZ2L2QhxVb3kRdjFTRLkGMxtRE2zlOtq87I=; b=YYECaj5WSYxI7n5yRnJXFTyoe0nKGD5yICsovLd02wlmnuSPgdYLUMuqYBlptRynsB MUpzWkeXbDT9fMSjaOjGGepo/eFpr4c9jQ9B2v/HhmZ7fv+OOdVChluvw0CM6XL0v3eB 2TFoOW7F0U/yc6N4GCWg1+AR4fs++5paSRr7roCr8J0PcW0X+0L/YYqUA8r3lOI0AZhQ kMGj80y2+wxaIATZjC2/SErByhl8fAka7p4zmL/r/diZ0UdRUoeucJ6tB0A2Ju02Tv4D xD1l7/v9HJwlipjereOgFVJbXexadb0Nx4OKS6s+xQpDzuiaBjA3Vsxl26wva21zX7iS mA2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771513415; x=1772118215; 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=TUoZFO6QDZ2L2QhxVb3kRdjFTRLkGMxtRE2zlOtq87I=; b=PpPHDy7QfVv+j2fvZ3q0oDz/zRwjY4afVJPn416NIU+4aLofz0H+r695uDqyTx6jXn YA2OSk7SorNy0QA+lEvHE0QUNllgeB6Cjpd1sCr9Kveq3uOIOv2/MS69F3fJz3J90L20 Olw2fP9pMavoNMHkSfu89rdNXWfck3QMZu1Lq+fLgy5gXIz4cY4adGB5j7kHh5cB4GzT M6umlzTu9L6MIsGxoNtZ4dZVbVIsKTjxd6//7We4AS3tlndvU/Upkoz14tEa7+SU6I+m viw+bc3L+TV0c19NCSMahTJxU0HC09wkKQtX3JkFnQhwXYUR9svCqQ9XjLgNuFRqanu7 X++g== X-Forwarded-Encrypted: i=1; AJvYcCUTHlbpPCBQWyPYJf9zu8cjzYFJUcFiI+cHSGuKBEnvAcWtLrKm5fqHOybNT1QAJwpdMhOS4n6KxwJYXcweHAPKbhY=@vger.kernel.org X-Gm-Message-State: AOJu0YyGAsobdwwyLamT6H+yyCzn1fVtA8ZZtdeaP0cYDNfAQN6CPc32 nvU7gMcNf1+7BS0K5NlmOyS0vRenvxA4IxBkR/vCyy3TcZXoLci8p91I+qcqMYnBsccxpKJlY+r 8+w30XsSjlmN2GUqK5AUa4Q== X-Received: from wmpz1.prod.google.com ([2002:a05:600c:a01:b0:483:8b61:16bd]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a7b:cde1:0:b0:483:7ae2:1737 with SMTP id 5b1f17b1804b1-4837ae2184fmr231128995e9.17.1771513413570; Thu, 19 Feb 2026 07:03:33 -0800 (PST) Date: Thu, 19 Feb 2026 15:02:51 +0000 In-Reply-To: <20260219150307.14538-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260219150307.14538-1-vdonnefort@google.com> X-Mailer: git-send-email 2.53.0.335.g19a08e0c02-goog Message-ID: <20260219150307.14538-15-vdonnefort@google.com> Subject: [PATCH v12 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" 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. Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index d9d8932a7b9c..43812bb7fcf8 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -664,6 +664,7 @@ 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 edbdd7b38f61..e130da35808f 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1287,4 +1287,12 @@ 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 2e39b09398b3..d106beca8d7f 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -130,4 +130,6 @@ 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..e5023b9d2611 --- /dev/null +++ b/kernel/trace/remote_test.c @@ -0,0 +1,261 @@ +// 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) { + WARN_ON(*per_cpu_ptr(&simple_rbs, cpu)); + *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; + } + + desc = kmalloc(desc_size, GFP_KERNEL); + if (!desc) { + ret = -ENOMEM; + goto err; + } + + 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_unload; + } + + remote_test_buffer_desc = desc; + + return remote_test_buffer_desc; + +err_unload: + 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: + 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; + + guard(preempt)(); + + 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) +); -- 2.53.0.335.g19a08e0c02-goog