v4.19.13 snapshot.
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
new file mode 100644
index 0000000..535eda7
--- /dev/null
+++ b/fs/proc/stat.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cpumask.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
+#include <linux/proc_fs.h>
+#include <linux/sched.h>
+#include <linux/sched/stat.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/irqnr.h>
+#include <linux/sched/cputime.h>
+#include <linux/tick.h>
+
+#ifndef arch_irq_stat_cpu
+#define arch_irq_stat_cpu(cpu) 0
+#endif
+#ifndef arch_irq_stat
+#define arch_irq_stat() 0
+#endif
+
+#ifdef arch_idle_time
+
+static u64 get_idle_time(int cpu)
+{
+ u64 idle;
+
+ idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
+ if (cpu_online(cpu) && !nr_iowait_cpu(cpu))
+ idle += arch_idle_time(cpu);
+ return idle;
+}
+
+static u64 get_iowait_time(int cpu)
+{
+ u64 iowait;
+
+ iowait = kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];
+ if (cpu_online(cpu) && nr_iowait_cpu(cpu))
+ iowait += arch_idle_time(cpu);
+ return iowait;
+}
+
+#else
+
+static u64 get_idle_time(int cpu)
+{
+ u64 idle, idle_usecs = -1ULL;
+
+ if (cpu_online(cpu))
+ idle_usecs = get_cpu_idle_time_us(cpu, NULL);
+
+ if (idle_usecs == -1ULL)
+ /* !NO_HZ or cpu offline so we can rely on cpustat.idle */
+ idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
+ else
+ idle = idle_usecs * NSEC_PER_USEC;
+
+ return idle;
+}
+
+static u64 get_iowait_time(int cpu)
+{
+ u64 iowait, iowait_usecs = -1ULL;
+
+ if (cpu_online(cpu))
+ iowait_usecs = get_cpu_iowait_time_us(cpu, NULL);
+
+ if (iowait_usecs == -1ULL)
+ /* !NO_HZ or cpu offline so we can rely on cpustat.iowait */
+ iowait = kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];
+ else
+ iowait = iowait_usecs * NSEC_PER_USEC;
+
+ return iowait;
+}
+
+#endif
+
+static int show_stat(struct seq_file *p, void *v)
+{
+ int i, j;
+ u64 user, nice, system, idle, iowait, irq, softirq, steal;
+ u64 guest, guest_nice;
+ u64 sum = 0;
+ u64 sum_softirq = 0;
+ unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
+ struct timespec64 boottime;
+
+ user = nice = system = idle = iowait =
+ irq = softirq = steal = 0;
+ guest = guest_nice = 0;
+ getboottime64(&boottime);
+
+ for_each_possible_cpu(i) {
+ user += kcpustat_cpu(i).cpustat[CPUTIME_USER];
+ nice += kcpustat_cpu(i).cpustat[CPUTIME_NICE];
+ system += kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
+ idle += get_idle_time(i);
+ iowait += get_iowait_time(i);
+ irq += kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
+ softirq += kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ];
+ steal += kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
+ guest += kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
+ guest_nice += kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
+ sum += kstat_cpu_irqs_sum(i);
+ sum += arch_irq_stat_cpu(i);
+
+ for (j = 0; j < NR_SOFTIRQS; j++) {
+ unsigned int softirq_stat = kstat_softirqs_cpu(j, i);
+
+ per_softirq_sums[j] += softirq_stat;
+ sum_softirq += softirq_stat;
+ }
+ }
+ sum += arch_irq_stat();
+
+ seq_put_decimal_ull(p, "cpu ", nsec_to_clock_t(user));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(nice));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(system));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(idle));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(iowait));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(irq));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(softirq));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(steal));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
+ seq_putc(p, '\n');
+
+ for_each_online_cpu(i) {
+ /* Copy values here to work around gcc-2.95.3, gcc-2.96 */
+ user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
+ nice = kcpustat_cpu(i).cpustat[CPUTIME_NICE];
+ system = kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
+ idle = get_idle_time(i);
+ iowait = get_iowait_time(i);
+ irq = kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
+ softirq = kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ];
+ steal = kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
+ guest = kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
+ guest_nice = kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
+ seq_printf(p, "cpu%d", i);
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(user));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(nice));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(system));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(idle));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(iowait));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(irq));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(softirq));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(steal));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
+ seq_putc(p, '\n');
+ }
+ seq_put_decimal_ull(p, "intr ", (unsigned long long)sum);
+
+ /* sum again ? it could be updated? */
+ for_each_irq_nr(j)
+ seq_put_decimal_ull(p, " ", kstat_irqs_usr(j));
+
+ seq_printf(p,
+ "\nctxt %llu\n"
+ "btime %llu\n"
+ "processes %lu\n"
+ "procs_running %lu\n"
+ "procs_blocked %lu\n",
+ nr_context_switches(),
+ (unsigned long long)boottime.tv_sec,
+ total_forks,
+ nr_running(),
+ nr_iowait());
+
+ seq_put_decimal_ull(p, "softirq ", (unsigned long long)sum_softirq);
+
+ for (i = 0; i < NR_SOFTIRQS; i++)
+ seq_put_decimal_ull(p, " ", per_softirq_sums[i]);
+ seq_putc(p, '\n');
+
+ return 0;
+}
+
+static int stat_open(struct inode *inode, struct file *file)
+{
+ unsigned int size = 1024 + 128 * num_online_cpus();
+
+ /* minimum size to display an interrupt count : 2 bytes */
+ size += 2 * nr_irqs;
+ return single_open_size(file, show_stat, NULL, size);
+}
+
+static const struct file_operations proc_stat_operations = {
+ .open = stat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init proc_stat_init(void)
+{
+ proc_create("stat", 0, NULL, &proc_stat_operations);
+ return 0;
+}
+fs_initcall(proc_stat_init);