ANDROID: uid_cputime: Adds accounting for the cputimes per uid.

Adds proc files /proc/uid_cputime/show_uid_stat and
/proc/uid_cputime/remove_uid_range.

show_uid_stat lists the total utime and stime for the active as well as
terminated processes for each of the uids.

Writing a range of uids to remove_uid_range will delete the accounting
for all the uids within that range.

Bug: 120442023
Change-Id: I21d9210379da730b33ddc1a0ea663c8c9d2ac15b
Signed-off-by: Jin Qian <jinqian@google.com>
[AmitP: Refactored the original patch because upstream commit
        605dc2b31a ("tsacct: Convert obsolete cputime type to nsecs")
        made cputime_t type obsolete, so use u64 nanoseconds directly instead.
        Also folded following android-4.9 changes into this patch
        48a9906c0f ("ANDROID: proc: uid_cputime: create uids from kuids")
        453ac31cab ("ANDROID: proc: uid_cputime: fix show_uid_stat permission")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
[connoro: Used by batterystats.]
[astrachan: Folded in the file/kconfig rename and the following changes:
            da3687fbc393 ("ANDROID: uid_cputime: fix cputime overflow")
            71e3eb512d00 ("ANDROID: uid_cputime: Iterates over all the threads instead of processes.")
            c65f0080c300 ("ANDROID: uid_cputime: Check for the range while removing range of UIDs.")
            c8212458e3a5 ("ANDROID: uid_sys_stats: fix access of task_uid(task)")
            bb5ee21cc4dd ("ANDROID: uid_sys_stats: change to use rt_mutex")
            6dc5d8173a8c ("ANDROID: uid_sys_stats: check previous uid_entry before call find_or_register_uid")
            82b9872b3894 ("ANDROID: uid_sys_stats: Replace tasklist lock with RCU in uid_cputime_show")]
Signed-off-by: Alistair Strachan <astrachan@google.com>

drivers/misc/Kconfig

@@ -513,6 +513,12 @@ config MISC_RTSX
 	tristate
 	default MISC_RTSX_PCI || MISC_RTSX_USB
 
+config UID_SYS_STATS
+	bool "Per-UID statistics"
+	depends on PROFILING
+	help
+	  Per UID based cpu time statistics exported to /proc/uid_cputime
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -58,3 +58,4 @@ obj-$(CONFIG_ASPEED_LPC_SNOOP)	+= aspeed-lpc-snoop.o
 obj-$(CONFIG_PCI_ENDPOINT_TEST)	+= pci_endpoint_test.o
 obj-$(CONFIG_OCXL)		+= ocxl/
 obj-$(CONFIG_MISC_RTSX)		+= cardreader/
+obj-$(CONFIG_UID_SYS_STATS)	+= uid_sys_stats.o

drivers/misc/uid_sys_stats.c

@@ -0,0 +1,241 @@
+/* drivers/misc/uid_sys_stats.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/rtmutex.h>
+#include <linux/sched/cputime.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_RT_MUTEX(uid_lock);
+static struct proc_dir_entry *parent;
+
+struct uid_entry {
+	uid_t uid;
+	u64 utime;
+	u64 stime;
+	u64 active_utime;
+	u64 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 = NULL;
+	struct task_struct *task, *temp;
+	struct user_namespace *user_ns = current_user_ns();
+	u64 utime;
+	u64 stime;
+	unsigned long bkt;
+	uid_t uid;
+
+	rt_mutex_lock(&uid_lock);
+
+	hash_for_each(hash_table, bkt, uid_entry, hash) {
+		uid_entry->active_stime = 0;
+		uid_entry->active_utime = 0;
+	}
+
+	rcu_read_lock();
+	do_each_thread(temp, task) {
+		uid = from_kuid_munged(user_ns, task_uid(task));
+		if (!uid_entry || uid_entry->uid != uid)
+			uid_entry = find_or_register_uid(uid);
+		if (!uid_entry) {
+			rcu_read_unlock();
+			rt_mutex_unlock(&uid_lock);
+			pr_err("%s: failed to find the uid_entry for uid %d\n",
+				__func__, uid);
+			return -ENOMEM;
+		}
+		task_cputime_adjusted(task, &utime, &stime);
+		uid_entry->active_utime += utime;
+		uid_entry->active_stime += stime;
+	} while_each_thread(temp, task);
+	rcu_read_unlock();
+
+	hash_for_each(hash_table, bkt, uid_entry, hash) {
+		u64 total_utime = uid_entry->utime +
+							uid_entry->active_utime;
+		u64 total_stime = uid_entry->stime +
+							uid_entry->active_stime;
+		seq_printf(m, "%d: %llu %llu\n", uid_entry->uid,
+			ktime_to_ms(total_utime), ktime_to_ms(total_stime));
+	}
+
+	rt_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;
+	}
+	rt_mutex_lock(&uid_lock);
+
+	for (; uid_start <= uid_end; uid_start++) {
+		hash_for_each_possible_safe(hash_table, uid_entry, tmp,
+							hash, (uid_t)uid_start) {
+			if (uid_start == uid_entry->uid) {
+				hash_del(&uid_entry->hash);
+				kfree(uid_entry);
+			}
+		}
+	}
+
+	rt_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;
+	u64 utime, stime;
+	uid_t uid;
+
+	if (!task)
+		return NOTIFY_OK;
+
+	rt_mutex_lock(&uid_lock);
+	uid = from_kuid_munged(current_user_ns(), 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:
+	rt_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_IRUGO, parent, &uid_stat_fops,
+					NULL);
+
+	profile_event_register(PROFILE_TASK_EXIT, &process_notifier_block);
+
+	return 0;
+}
+
+early_initcall(proc_uid_cputime_init);