--- /dev/null
+/* drivers/misc/uid_cputime.c
+ *
+ * Copyright (C) 2014 - 2015 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/atomic.h>
+#include <linux/err.h>
+#include <linux/hashtable.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/proc_fs.h>
+#include <linux/profile.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#define UID_HASH_BITS 10
+DECLARE_HASHTABLE(hash_table, UID_HASH_BITS);
+
+static DEFINE_MUTEX(uid_lock);
+static struct proc_dir_entry *parent;
+
+struct uid_entry {
+ uid_t uid;
+ cputime_t utime;
+ cputime_t stime;
+ cputime_t active_utime;
+ cputime_t active_stime;
+ struct hlist_node hash;
+};
+
+static struct uid_entry *find_uid_entry(uid_t uid)
+{
+ struct uid_entry *uid_entry;
+ hash_for_each_possible(hash_table, uid_entry, hash, uid) {
+ if (uid_entry->uid == uid)
+ return uid_entry;
+ }
+ return NULL;
+}
+
+static struct uid_entry *find_or_register_uid(uid_t uid)
+{
+ struct uid_entry *uid_entry;
+
+ uid_entry = find_uid_entry(uid);
+ if (uid_entry)
+ return uid_entry;
+
+ uid_entry = kzalloc(sizeof(struct uid_entry), GFP_ATOMIC);
+ if (!uid_entry)
+ return NULL;
+
+ uid_entry->uid = uid;
+
+ hash_add(hash_table, &uid_entry->hash, uid);
+
+ return uid_entry;
+}
+
+static int uid_stat_show(struct seq_file *m, void *v)
+{
+ struct uid_entry *uid_entry;
+ struct task_struct *task;
+ cputime_t utime;
+ cputime_t stime;
+ unsigned long bkt;
+
+ mutex_lock(&uid_lock);
+
+ hash_for_each(hash_table, bkt, uid_entry, hash) {
+ uid_entry->active_stime = 0;
+ uid_entry->active_utime = 0;
+ }
+
+ read_lock(&tasklist_lock);
+ for_each_process(task) {
+ uid_entry = find_or_register_uid(task_uid(task));
+ if (!uid_entry) {
+ read_unlock(&tasklist_lock);
+ mutex_unlock(&uid_lock);
+ pr_err("%s: failed to find the uid_entry for uid %d\n",
+ __func__, task_uid(task));
+ return -ENOMEM;
+ }
+ task_cputime_adjusted(task, &utime, &stime);
+ uid_entry->active_utime += utime;
+ uid_entry->active_stime += stime;
+ }
+ read_unlock(&tasklist_lock);
+
+ hash_for_each(hash_table, bkt, uid_entry, hash) {
+ cputime_t total_utime = uid_entry->utime +
+ uid_entry->active_utime;
+ cputime_t total_stime = uid_entry->stime +
+ uid_entry->active_stime;
+ seq_printf(m, "%d: %u %u\n", uid_entry->uid,
+ cputime_to_usecs(total_utime),
+ cputime_to_usecs(total_stime));
+ }
+
+ mutex_unlock(&uid_lock);
+ return 0;
+}
+
+static int uid_stat_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, uid_stat_show, PDE_DATA(inode));
+}
+
+static const struct file_operations uid_stat_fops = {
+ .open = uid_stat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int uid_remove_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, NULL, NULL);
+}
+
+static ssize_t uid_remove_write(struct file *file,
+ const char __user *buffer, size_t count, loff_t *ppos)
+{
+ struct uid_entry *uid_entry;
+ struct hlist_node *tmp;
+ char uids[128];
+ char *start_uid, *end_uid = NULL;
+ long int uid_start = 0, uid_end = 0;
+
+ if (count >= sizeof(uids))
+ count = sizeof(uids) - 1;
+
+ if (copy_from_user(uids, buffer, count))
+ return -EFAULT;
+
+ uids[count] = '\0';
+ end_uid = uids;
+ start_uid = strsep(&end_uid, "-");
+
+ if (!start_uid || !end_uid)
+ return -EINVAL;
+
+ if (kstrtol(start_uid, 10, &uid_start) != 0 ||
+ kstrtol(end_uid, 10, &uid_end) != 0) {
+ return -EINVAL;
+ }
+
+ mutex_lock(&uid_lock);
+
+ for (; uid_start <= uid_end; uid_start++) {
+ hash_for_each_possible_safe(hash_table, uid_entry, tmp,
+ hash, uid_start) {
+ hash_del(&uid_entry->hash);
+ kfree(uid_entry);
+ }
+ }
+
+ mutex_unlock(&uid_lock);
+ return count;
+}
+
+static const struct file_operations uid_remove_fops = {
+ .open = uid_remove_open,
+ .release = single_release,
+ .write = uid_remove_write,
+};
+
+static int process_notifier(struct notifier_block *self,
+ unsigned long cmd, void *v)
+{
+ struct task_struct *task = v;
+ struct uid_entry *uid_entry;
+ cputime_t utime, stime;
+ uid_t uid;
+
+ if (!task)
+ return NOTIFY_OK;
+
+ mutex_lock(&uid_lock);
+ uid = task_uid(task);
+ uid_entry = find_or_register_uid(uid);
+ if (!uid_entry) {
+ pr_err("%s: failed to find uid %d\n", __func__, uid);
+ goto exit;
+ }
+
+ task_cputime_adjusted(task, &utime, &stime);
+ uid_entry->utime += utime;
+ uid_entry->stime += stime;
+
+exit:
+ mutex_unlock(&uid_lock);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block process_notifier_block = {
+ .notifier_call = process_notifier,
+};
+
+static int __init proc_uid_cputime_init(void)
+{
+ hash_init(hash_table);
+
+ parent = proc_mkdir("uid_cputime", NULL);
+ if (!parent) {
+ pr_err("%s: failed to create proc entry\n", __func__);
+ return -ENOMEM;
+ }
+
+ proc_create_data("remove_uid_range", S_IWUGO, parent, &uid_remove_fops,
+ NULL);
+
+ proc_create_data("show_uid_stat", S_IWUGO, parent, &uid_stat_fops,
+ NULL);
+
+ profile_event_register(PROFILE_TASK_EXIT, &process_notifier_block);
+
+ return 0;
+}
+
+early_initcall(proc_uid_cputime_init);
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