From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (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 8F833335540 for ; Mon, 26 Jan 2026 10:44:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769424283; cv=none; b=GqvG9HkzWJq31sQuRWrINTvNkFf/8i8obfmLmC9SCWPLFi19KKcA/oXTa7sdeN1v4bpeOVNKEamYql2AUmdktBk0WsoIRy0lTXxUgzcC/bxkS4KGWtg5sUBqQDDl8eYiM3fqQ8MwNUTphuAw993Gm2O9XvC5aJSznyU/wLFBvB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769424283; c=relaxed/simple; bh=bPFRL692BOvU5DvpfyFvfhyxsnSIaPLNNQFJH0MR+7w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hulgNuLvlcS5UhyWRpDAKlGVDuyx+23Lbhv/ef7g2VSC5aJBmYOHXXZZ4fvb6OoKzuPO9j407kJZa6FuXLIGpTNt43dlGBdeh81bbluCtkvfkhRtoR2Q7e4Z1yJ2Z4sP3OZD0TWPY/XQvYt/ZMg0IKvyCivoxSt9JPWclkUTLBo= 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=WEnzkRax; arc=none smtp.client-ip=209.85.128.73 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WEnzkRax" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-47ee868f5adso45986425e9.0 for ; Mon, 26 Jan 2026 02:44:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1769424279; x=1770029079; 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=bTaG7ti7EadExoRYTduoC20Wwf7BQw6/YXyO13ReAkY=; b=WEnzkRaxAG4Lw6Thwvll6HAj+Wvg77ST4ZP2uiEHlUOK2dCNeF2LxWwlbI/rplvPvy vJftew6OvGnL3Wu83NogRzdmCH/xBMECfGHzhyzyMaokaE9Gwh1O/01h6SSXVBhaxZL8 UL0bvzOEHAvxJFJWwuAqNFwdz8tsGyPEz6UmG0qPJu6jpaf1nmzrCbVmzo50Dn/6M0T/ k/o0kcfEM6M6eb5jN8DJJcBNhKx25LkQasEkxSx+PL1k2kc9j0oKf/+gwOJJ41VIUQB/ /bK/gfC0vP2YX7Ckt2cdmclaGGvS1LRd7OhjiFMpjzPHCiRKOlolLtUhcRMoaUCOtQXF RSrg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769424279; x=1770029079; 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=bTaG7ti7EadExoRYTduoC20Wwf7BQw6/YXyO13ReAkY=; b=HnvYL5WTNIKCOZNHmxF5SkXOe9e9yoNryTDqDvCSM5+RFYQEy3nmxNKyrme0M5yFYc dZV2qlcSOf2DnsaxHNrb8iytxCYFCDaYP3RwwHVRYY5ZXyAx58zGqhiVmrcAHn6x/FpD bDIFQVqIkHoEWvW5a/jwcRmzewpuXNDv6X9v8BGV+lxbYwGZeUJLE3PQrxWEXqpcrUVr bkvrDQNmeuRe0aOWEy6ycsr56uZNvfYjTVXlwheEyudRbdn6CYqVby5oTwIsu6qV81Hx 9BaTfUH6Vb5rkrusJOWTx56LQd9TdSccHL6wagdu4ehGVIXqpiqhgzSSuCTpozdT8mRp UxUA== X-Forwarded-Encrypted: i=1; AJvYcCUuNSlxf9tjjolNjXAm40bnmfC+08yR52in00+iRNKaYn2F6IC8EB80DPmz5moG9PPdz8mG1WgiZX/qO2qwEAC/9Ew=@vger.kernel.org X-Gm-Message-State: AOJu0YzPEleTRyaJsTuytSMiRG/qfqaqbjPE4sB1w4sTorMsnn/xSL/P okykmFUsJUgowwbQ7RqNMZQw0RwHHW/pvBTdl1GQjd/s0KmynubNZCqYw3URDKQjuCQGM7qqoIf fbAHgvEi8cdgLY1XvQ+hwjg== X-Received: from wmjv4.prod.google.com ([2002:a7b:cb44:0:b0:480:2051:60e1]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:699a:b0:479:3a89:121d with SMTP id 5b1f17b1804b1-4805d066135mr64170645e9.36.1769424278959; Mon, 26 Jan 2026 02:44:38 -0800 (PST) Date: Mon, 26 Jan 2026 10:44:03 +0000 In-Reply-To: <20260126104419.1649811-1-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: <20260126104419.1649811-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260126104419.1649811-15-vdonnefort@google.com> Subject: [PATCH v10 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. 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 dfaf1af8862e..994d0c279060 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1284,4 +1284,12 @@ 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 efe12e282f8c..9e86c43bf320 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -129,4 +129,6 @@ 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) +); -- 2.52.0.457.g6b5491de43-goog