From patchwork Thu Jul 7 21:58:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 12910284 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82853CCA482 for ; Thu, 7 Jul 2022 21:58:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236878AbiGGV6h (ORCPT ); Thu, 7 Jul 2022 17:58:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236832AbiGGV6g (ORCPT ); Thu, 7 Jul 2022 17:58:36 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 76C731F624; Thu, 7 Jul 2022 14:58:33 -0700 (PDT) Received: from localhost.localdomain (unknown [98.59.227.103]) by linux.microsoft.com (Postfix) with ESMTPSA id E6E3B20A8983; Thu, 7 Jul 2022 14:58:32 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E6E3B20A8983 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1657231113; bh=BxI5UolQGAsnMdyCvuimOLm8oafKKEXyRJ7WoCQTwHQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U4lPltXaW5xgUTFqt4heA9DVVlpOCF4htM25mMLoBLLO+lBfLpdq5zDgfqqWLUZ0J NIsYFT+QgoXD+86EWxPCJPVU6PshcU8aJrlRfQ5j4DozqslD8CfS/j5TVzYG3l2xCB ddjBOvmn5el4Mr7Jic4i2AEiJNlo4tdO2XHNit9k= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 4/7] tracing/user_events: Move pages/locks into groups to prepare for namespaces Date: Thu, 7 Jul 2022 14:58:25 -0700 Message-Id: <20220707215828.2021-5-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220707215828.2021-1-beaub@linux.microsoft.com> References: <20220707215828.2021-1-beaub@linux.microsoft.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org In order to enable namespaces or any sort of isolation within user_events the register lock and pages need to be broken up into groups. Each event and file now has a group pointer which stores the actual pages to map, lookup data and synchronization objects. Signed-off-by: Beau Belgrave --- kernel/trace/trace_events_user.c | 381 ++++++++++++++++++++++++------- 1 file changed, 304 insertions(+), 77 deletions(-) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 7bff4c8b90f2..8ffbb9ce2f1a 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -51,11 +51,23 @@ #define EVENT_STATUS_PERF (1 << 1) #define EVENT_STATUS_OTHER (1 << 7) -static char *register_page_data; +struct user_event_group { + struct page *pages; + char *register_page_data; + char *system_name; + struct dentry *status_file; + struct dentry *data_file; + struct hlist_node node; + struct mutex reg_mutex; + DECLARE_HASHTABLE(register_table, 8); + DECLARE_BITMAP(page_bitmap, MAX_EVENTS); + refcount_t refcnt; + int id; +}; -static DEFINE_MUTEX(reg_mutex); -static DEFINE_HASHTABLE(register_table, 8); -static DECLARE_BITMAP(page_bitmap, MAX_EVENTS); +static DEFINE_HASHTABLE(group_table, 8); +static DEFINE_MUTEX(group_mutex); +static struct user_event_group *root_group; /* * Stores per-event properties, as users register events @@ -65,6 +77,7 @@ static DECLARE_BITMAP(page_bitmap, MAX_EVENTS); * refcnt reaches one. */ struct user_event { + struct user_event_group *group; struct tracepoint tracepoint; struct trace_event_call call; struct trace_event_class class; @@ -91,6 +104,11 @@ struct user_event_refs { struct user_event *events[]; }; +struct user_event_file_info { + struct user_event_group *group; + struct user_event_refs *refs; +}; + #define VALIDATOR_ENSURE_NULL (1 << 0) #define VALIDATOR_REL (1 << 1) @@ -103,7 +121,8 @@ struct user_event_validator { typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i, void *tpdata, bool *faulted); -static int user_event_parse(char *name, char *args, char *flags, +static int user_event_parse(struct user_event_group *group, char *name, + char *args, char *flags, struct user_event **newuser); static u32 user_event_key(char *name) @@ -111,12 +130,132 @@ static u32 user_event_key(char *name) return jhash(name, strlen(name), 0); } +static void set_page_reservations(char *pages, bool set) +{ + int page; + + for (page = 0; page < MAX_PAGES; ++page) { + void *addr = pages + (PAGE_SIZE * page); + + if (set) + SetPageReserved(virt_to_page(addr)); + else + ClearPageReserved(virt_to_page(addr)); + } +} + +static void user_event_group_destroy(struct user_event_group *group) +{ + if (group->status_file) + tracefs_remove(group->status_file); + + if (group->data_file) + tracefs_remove(group->status_file); + + if (group->register_page_data) + set_page_reservations(group->register_page_data, false); + + if (group->pages) + __free_pages(group->pages, MAX_PAGE_ORDER); + + kfree(group->system_name); + kfree(group); +} + +static char *user_event_group_system_name(const char *name) +{ + char *system_name; + int len = strlen(name) + sizeof(USER_EVENTS_SYSTEM) + 1; + + system_name = kmalloc(len, GFP_KERNEL); + + if (!system_name) + return NULL; + + snprintf(system_name, len, "%s.%s", USER_EVENTS_SYSTEM, name); + + return system_name; +} + +static __always_inline +void user_event_group_release(struct user_event_group *group) +{ + refcount_dec(&group->refcnt); +} + +static struct user_event_group *user_event_group_find(int id) +{ + struct user_event_group *group; + + mutex_lock(&group_mutex); + + hash_for_each_possible(group_table, group, node, id) + if (group->id == id) { + refcount_inc(&group->refcnt); + mutex_unlock(&group_mutex); + return group; + } + + mutex_unlock(&group_mutex); + + return NULL; +} + +static struct user_event_group *user_event_group_create(const char *name, + int id) +{ + struct user_event_group *group; + + group = kzalloc(sizeof(*group), GFP_KERNEL); + + if (!group) + return NULL; + + if (name) { + group->system_name = user_event_group_system_name(name); + + if (!group->system_name) + goto error; + } + + group->pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER); + + if (!group->pages) + goto error; + + group->register_page_data = page_address(group->pages); + + set_page_reservations(group->register_page_data, true); + + /* Zero all bits beside 0 (which is reserved for failures) */ + bitmap_zero(group->page_bitmap, MAX_EVENTS); + set_bit(0, group->page_bitmap); + + mutex_init(&group->reg_mutex); + hash_init(group->register_table); + + /* Mark and add to lookup */ + group->id = id; + refcount_set(&group->refcnt, 2); + + mutex_lock(&group_mutex); + hash_add(group_table, &group->node, group->id); + mutex_unlock(&group_mutex); + + return group; +error: + if (group) + user_event_group_destroy(group); + + return NULL; +}; + static __always_inline void user_event_register_set(struct user_event *user) { int i = user->index; - register_page_data[STATUS_BYTE(i)] |= STATUS_MASK(i); + user->group->register_page_data[STATUS_BYTE(i)] |= STATUS_MASK(i); } static __always_inline @@ -124,7 +263,7 @@ void user_event_register_clear(struct user_event *user) { int i = user->index; - register_page_data[STATUS_BYTE(i)] &= ~STATUS_MASK(i); + user->group->register_page_data[STATUS_BYTE(i)] &= ~STATUS_MASK(i); } static __always_inline __must_check @@ -168,7 +307,8 @@ static struct list_head *user_event_get_fields(struct trace_event_call *call) * * Upon success user_event has its ref count increased by 1. */ -static int user_event_parse_cmd(char *raw_command, struct user_event **newuser) +static int user_event_parse_cmd(struct user_event_group *group, + char *raw_command, struct user_event **newuser) { char *name = raw_command; char *args = strpbrk(name, " "); @@ -182,7 +322,7 @@ static int user_event_parse_cmd(char *raw_command, struct user_event **newuser) if (flags) *flags++ = '\0'; - return user_event_parse(name, args, flags, newuser); + return user_event_parse(group, name, args, flags, newuser); } static int user_field_array_size(const char *type) @@ -670,7 +810,7 @@ static int destroy_user_event(struct user_event *user) dyn_event_remove(&user->devent); user_event_register_clear(user); - clear_bit(user->index, page_bitmap); + clear_bit(user->index, user->group->page_bitmap); hash_del(&user->node); user_event_destroy_validators(user); @@ -681,14 +821,15 @@ static int destroy_user_event(struct user_event *user) return ret; } -static struct user_event *find_user_event(char *name, u32 *outkey) +static struct user_event *find_user_event(struct user_event_group *group, + char *name, u32 *outkey) { struct user_event *user; u32 key = user_event_key(name); *outkey = key; - hash_for_each_possible(register_table, user, node, key) + hash_for_each_possible(group->register_table, user, node, key) if (!strcmp(EVENT_NAME(user), name)) { refcount_inc(&user->refcnt); return user; @@ -935,14 +1076,14 @@ static int user_event_create(const char *raw_command) if (!name) return -ENOMEM; - mutex_lock(®_mutex); + mutex_lock(&root_group->reg_mutex); - ret = user_event_parse_cmd(name, &user); + ret = user_event_parse_cmd(root_group, name, &user); if (!ret) refcount_dec(&user->refcnt); - mutex_unlock(®_mutex); + mutex_unlock(&root_group->reg_mutex); if (ret) kfree(name); @@ -1096,7 +1237,8 @@ static int user_event_trace_register(struct user_event *user) * The name buffer lifetime is owned by this method for success cases only. * Upon success the returned user_event has its ref count increased by 1. */ -static int user_event_parse(char *name, char *args, char *flags, +static int user_event_parse(struct user_event_group *group, char *name, + char *args, char *flags, struct user_event **newuser) { int ret; @@ -1106,7 +1248,7 @@ static int user_event_parse(char *name, char *args, char *flags, /* Prevent dyn_event from racing */ mutex_lock(&event_mutex); - user = find_user_event(name, &key); + user = find_user_event(group, name, &key); mutex_unlock(&event_mutex); if (user) { @@ -1119,7 +1261,7 @@ static int user_event_parse(char *name, char *args, char *flags, return 0; } - index = find_first_zero_bit(page_bitmap, MAX_EVENTS); + index = find_first_zero_bit(group->page_bitmap, MAX_EVENTS); if (index == MAX_EVENTS) return -EMFILE; @@ -1133,6 +1275,7 @@ static int user_event_parse(char *name, char *args, char *flags, INIT_LIST_HEAD(&user->fields); INIT_LIST_HEAD(&user->validators); + user->group = group; user->tracepoint.name = name; ret = user_event_parse_fields(user, args); @@ -1152,7 +1295,11 @@ static int user_event_parse(char *name, char *args, char *flags, user->call.tp = &user->tracepoint; user->call.event.funcs = &user_event_funcs; - user->class.system = USER_EVENTS_SYSTEM; + if (group->system_name) + user->class.system = group->system_name; + else + user->class.system = USER_EVENTS_SYSTEM; + user->class.fields_array = user_event_fields_array; user->class.get_fields = user_event_get_fields; user->class.reg = user_event_reg; @@ -1175,8 +1322,8 @@ static int user_event_parse(char *name, char *args, char *flags, dyn_event_init(&user->devent, &user_event_dops); dyn_event_add(&user->devent, &user->call); - set_bit(user->index, page_bitmap); - hash_add(register_table, &user->node, key); + set_bit(user->index, group->page_bitmap); + hash_add(group->register_table, &user->node, key); mutex_unlock(&event_mutex); @@ -1194,10 +1341,10 @@ static int user_event_parse(char *name, char *args, char *flags, /* * Deletes a previously created event if it is no longer being used. */ -static int delete_user_event(char *name) +static int delete_user_event(struct user_event_group *group, char *name) { u32 key; - struct user_event *user = find_user_event(name, &key); + struct user_event *user = find_user_event(group, name, &key); if (!user) return -ENOENT; @@ -1215,6 +1362,7 @@ static int delete_user_event(char *name) */ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i) { + struct user_event_file_info *info = file->private_data; struct user_event_refs *refs; struct user_event *user = NULL; struct tracepoint *tp; @@ -1226,7 +1374,7 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i) rcu_read_lock_sched(); - refs = rcu_dereference_sched(file->private_data); + refs = rcu_dereference_sched(info->refs); /* * The refs->events array is protected by RCU, and new items may be @@ -1284,6 +1432,30 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i) return ret; } +static int user_events_open(struct inode *node, struct file *file) +{ + struct user_event_group *group; + struct user_event_file_info *info; + + group = user_event_group_find((int)(uintptr_t)node->i_private); + + if (!group) + return -ENOENT; + + info = kzalloc(sizeof(*info), GFP_KERNEL); + + if (!info) { + user_event_group_release(group); + return -ENOMEM; + } + + info->group = group; + + file->private_data = info; + + return 0; +} + static ssize_t user_events_write(struct file *file, const char __user *ubuf, size_t count, loff_t *ppos) { @@ -1305,13 +1477,15 @@ static ssize_t user_events_write_iter(struct kiocb *kp, struct iov_iter *i) return user_events_write_core(kp->ki_filp, i); } -static int user_events_ref_add(struct file *file, struct user_event *user) +static int user_events_ref_add(struct user_event_file_info *info, + struct user_event *user) { + struct user_event_group *group = info->group; struct user_event_refs *refs, *new_refs; int i, size, count = 0; - refs = rcu_dereference_protected(file->private_data, - lockdep_is_held(®_mutex)); + refs = rcu_dereference_protected(info->refs, + lockdep_is_held(&group->reg_mutex)); if (refs) { count = refs->count; @@ -1337,7 +1511,7 @@ static int user_events_ref_add(struct file *file, struct user_event *user) refcount_inc(&user->refcnt); - rcu_assign_pointer(file->private_data, new_refs); + rcu_assign_pointer(info->refs, new_refs); if (refs) kfree_rcu(refs, rcu); @@ -1374,7 +1548,8 @@ static long user_reg_get(struct user_reg __user *ureg, struct user_reg *kreg) /* * Registers a user_event on behalf of a user process. */ -static long user_events_ioctl_reg(struct file *file, unsigned long uarg) +static long user_events_ioctl_reg(struct user_event_file_info *info, + unsigned long uarg) { struct user_reg __user *ureg = (struct user_reg __user *)uarg; struct user_reg reg; @@ -1395,14 +1570,14 @@ static long user_events_ioctl_reg(struct file *file, unsigned long uarg) return ret; } - ret = user_event_parse_cmd(name, &user); + ret = user_event_parse_cmd(info->group, name, &user); if (ret) { kfree(name); return ret; } - ret = user_events_ref_add(file, user); + ret = user_events_ref_add(info, user); /* No longer need parse ref, ref_add either worked or not */ refcount_dec(&user->refcnt); @@ -1420,7 +1595,8 @@ static long user_events_ioctl_reg(struct file *file, unsigned long uarg) /* * Deletes a user_event on behalf of a user process. */ -static long user_events_ioctl_del(struct file *file, unsigned long uarg) +static long user_events_ioctl_del(struct user_event_file_info *info, + unsigned long uarg) { void __user *ubuf = (void __user *)uarg; char *name; @@ -1433,7 +1609,7 @@ static long user_events_ioctl_del(struct file *file, unsigned long uarg) /* event_mutex prevents dyn_event from racing */ mutex_lock(&event_mutex); - ret = delete_user_event(name); + ret = delete_user_event(info->group, name); mutex_unlock(&event_mutex); kfree(name); @@ -1447,19 +1623,21 @@ static long user_events_ioctl_del(struct file *file, unsigned long uarg) static long user_events_ioctl(struct file *file, unsigned int cmd, unsigned long uarg) { + struct user_event_file_info *info = file->private_data; + struct user_event_group *group = info->group; long ret = -ENOTTY; switch (cmd) { case DIAG_IOCSREG: - mutex_lock(®_mutex); - ret = user_events_ioctl_reg(file, uarg); - mutex_unlock(®_mutex); + mutex_lock(&group->reg_mutex); + ret = user_events_ioctl_reg(info, uarg); + mutex_unlock(&group->reg_mutex); break; case DIAG_IOCSDEL: - mutex_lock(®_mutex); - ret = user_events_ioctl_del(file, uarg); - mutex_unlock(®_mutex); + mutex_lock(&group->reg_mutex); + ret = user_events_ioctl_del(info, uarg); + mutex_unlock(&group->reg_mutex); break; } @@ -1471,17 +1649,24 @@ static long user_events_ioctl(struct file *file, unsigned int cmd, */ static int user_events_release(struct inode *node, struct file *file) { + struct user_event_file_info *info = file->private_data; + struct user_event_group *group; struct user_event_refs *refs; struct user_event *user; int i; + if (!info) + return -EINVAL; + + group = info->group; + /* * Ensure refs cannot change under any situation by taking the * register mutex during the final freeing of the references. */ - mutex_lock(®_mutex); + mutex_lock(&group->reg_mutex); - refs = file->private_data; + refs = info->refs; if (!refs) goto out; @@ -1500,32 +1685,54 @@ static int user_events_release(struct inode *node, struct file *file) out: file->private_data = NULL; - mutex_unlock(®_mutex); + mutex_unlock(&group->reg_mutex); kfree(refs); + kfree(info); + + /* No longer using group */ + user_event_group_release(group); return 0; } static const struct file_operations user_data_fops = { + .open = user_events_open, .write = user_events_write, .write_iter = user_events_write_iter, .unlocked_ioctl = user_events_ioctl, .release = user_events_release, }; +static struct user_event_group *user_status_group(struct file *file) +{ + struct seq_file *m = file->private_data; + + if (!m) + return NULL; + + return m->private; +} + /* * Maps the shared page into the user process for checking if event is enabled. */ static int user_status_mmap(struct file *file, struct vm_area_struct *vma) { + char *pages; + struct user_event_group *group = user_status_group(file); unsigned long size = vma->vm_end - vma->vm_start; if (size != MAX_BYTES) return -EINVAL; + if (!group) + return -EINVAL; + + pages = group->register_page_data; + return remap_pfn_range(vma, vma->vm_start, - virt_to_phys(register_page_data) >> PAGE_SHIFT, + virt_to_phys(pages) >> PAGE_SHIFT, size, vm_get_page_prot(VM_READ)); } @@ -1549,13 +1756,17 @@ static void user_seq_stop(struct seq_file *m, void *p) static int user_seq_show(struct seq_file *m, void *p) { + struct user_event_group *group = m->private; struct user_event *user; char status; int i, active = 0, busy = 0, flags; - mutex_lock(®_mutex); + if (!group) + return -EINVAL; + + mutex_lock(&group->reg_mutex); - hash_for_each(register_table, i, user, node) { + hash_for_each(group->register_table, i, user, node) { status = user->status; flags = user->flags; @@ -1579,7 +1790,7 @@ static int user_seq_show(struct seq_file *m, void *p) active++; } - mutex_unlock(®_mutex); + mutex_unlock(&group->reg_mutex); seq_puts(m, "\n"); seq_printf(m, "Active: %d\n", active); @@ -1598,7 +1809,38 @@ static const struct seq_operations user_seq_ops = { static int user_status_open(struct inode *node, struct file *file) { - return seq_open(file, &user_seq_ops); + struct user_event_group *group; + int ret; + + group = user_event_group_find((int)(uintptr_t)node->i_private); + + if (!group) + return -ENOENT; + + ret = seq_open(file, &user_seq_ops); + + if (!ret) { + /* Chain group to seq_file */ + struct seq_file *m = file->private_data; + + m->private = group; + } else { + user_event_group_release(group); + } + + return ret; +} + +static int user_status_release(struct inode *node, struct file *file) +{ + struct user_event_group *group = user_status_group(file); + + if (group) + user_event_group_release(group); + else + pr_warn("user_events: No group attached to status file\n"); + + return seq_release(node, file); } static const struct file_operations user_status_fops = { @@ -1606,18 +1848,20 @@ static const struct file_operations user_status_fops = { .mmap = user_status_mmap, .read = seq_read, .llseek = seq_lseek, - .release = seq_release, + .release = user_status_release, }; /* * Creates a set of tracefs files to allow user mode interactions. */ -static int create_user_tracefs(void) +static int create_user_tracefs(struct dentry *parent, + struct user_event_group *group) { struct dentry *edata, *emmap; edata = tracefs_create_file("user_events_data", TRACE_MODE_WRITE, - NULL, NULL, &user_data_fops); + parent, (void *)(uintptr_t)group->id, + &user_data_fops); if (!edata) { pr_warn("Could not create tracefs 'user_events_data' entry\n"); @@ -1626,7 +1870,8 @@ static int create_user_tracefs(void) /* mmap with MAP_SHARED requires writable fd */ emmap = tracefs_create_file("user_events_status", TRACE_MODE_WRITE, - NULL, NULL, &user_status_fops); + parent, (void *)(uintptr_t)group->id, + &user_status_fops); if (!emmap) { tracefs_remove(edata); @@ -1634,47 +1879,29 @@ static int create_user_tracefs(void) goto err; } + group->data_file = edata; + group->status_file = emmap; + return 0; err: return -ENODEV; } -static void set_page_reservations(bool set) -{ - int page; - - for (page = 0; page < MAX_PAGES; ++page) { - void *addr = register_page_data + (PAGE_SIZE * page); - - if (set) - SetPageReserved(virt_to_page(addr)); - else - ClearPageReserved(virt_to_page(addr)); - } -} - static int __init trace_events_user_init(void) { - struct page *pages; int ret; - /* Zero all bits beside 0 (which is reserved for failures) */ - bitmap_zero(page_bitmap, MAX_EVENTS); - set_bit(0, page_bitmap); + root_group = user_event_group_create(NULL, 0); - pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER); - if (!pages) + if (!root_group) return -ENOMEM; - register_page_data = page_address(pages); - - set_page_reservations(true); - ret = create_user_tracefs(); + ret = create_user_tracefs(NULL, root_group); if (ret) { pr_warn("user_events could not register with tracefs\n"); - set_page_reservations(false); - __free_pages(pages, MAX_PAGE_ORDER); + user_event_group_destroy(root_group); + root_group = NULL; return ret; }