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/* Copyright (c) 2013-2014, 2017 The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* 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/uaccess.h>
#include <linux/debugfs.h>
#include <linux/cpu.h>
#include <linux/tracepoint.h>
#include <trace/events/sched.h>
#define CREATE_TRACE_POINTS
#include "perf_trace_counters.h"
static unsigned int tp_pid_state;
DEFINE_PER_CPU(u32, cntenset_val);
DEFINE_PER_CPU(u32, previous_ccnt);
DEFINE_PER_CPU(u32[NUM_L1_CTRS], previous_l1_cnts);
DEFINE_PER_CPU(u32, old_pid);
DEFINE_PER_CPU(u32, hotplug_flag);
static int tracectr_cpu_hotplug_notifier(struct notifier_block *self,
unsigned long action, void *hcpu)
{
unsigned long cpu = (unsigned long)hcpu;
if ((action & (~CPU_TASKS_FROZEN)) == CPU_STARTING)
per_cpu(hotplug_flag, cpu) = 1;
return NOTIFY_OK;
}
static struct notifier_block tracectr_cpu_hotplug_notifier_block = {
.notifier_call = tracectr_cpu_hotplug_notifier,
};
static void setup_prev_cnts(u32 cpu, u32 cnten_val)
{
int i;
if (cnten_val & CC)
asm volatile("mrs %0, pmccntr_el0"
: "=r"(per_cpu(previous_ccnt, cpu)));
for (i = 0; i < NUM_L1_CTRS; i++) {
if (cnten_val & (1 << i)) {
/* Select */
asm volatile("msr pmselr_el0, %0" : : "r"(i));
isb();
/* Read value */
asm volatile("mrs %0, pmxevcntr_el0"
: "=r"(per_cpu(previous_l1_cnts[i], cpu)));
}
}
}
void tracectr_notifier(void *ignore, bool preempt,
struct task_struct *prev, struct task_struct *next)
{
u32 cnten_val;
int current_pid;
u32 cpu = task_cpu(next);
if (tp_pid_state != 1)
return;
current_pid = next->pid;
if (per_cpu(old_pid, cpu) != -1) {
asm volatile("mrs %0, pmcntenset_el0" : "=r" (cnten_val));
per_cpu(cntenset_val, cpu) = cnten_val;
/* Disable all the counters that were enabled */
asm volatile("msr pmcntenclr_el0, %0" : : "r" (cnten_val));
if (per_cpu(hotplug_flag, cpu) == 1) {
per_cpu(hotplug_flag, cpu) = 0;
setup_prev_cnts(cpu, cnten_val);
} else {
trace_sched_switch_with_ctrs(per_cpu(old_pid, cpu),
current_pid);
}
/* Enable all the counters that were disabled */
asm volatile("msr pmcntenset_el0, %0" : : "r" (cnten_val));
}
per_cpu(old_pid, cpu) = current_pid;
}
static void enable_tp_pid(void)
{
if (tp_pid_state == 0) {
tp_pid_state = 1;
register_trace_sched_switch(tracectr_notifier, NULL);
}
}
static void disable_tp_pid(void)
{
if (tp_pid_state == 1) {
tp_pid_state = 0;
unregister_trace_sched_switch(tracectr_notifier, NULL);
}
}
static ssize_t read_enabled_perftp_file_bool(struct file *file,
char __user *user_buf, size_t count, loff_t *ppos)
{
char buf[2];
buf[1] = '\n';
if (tp_pid_state == 0)
buf[0] = '0';
else
buf[0] = '1';
return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}
static ssize_t write_enabled_perftp_file_bool(struct file *file,
const char __user *user_buf, size_t count, loff_t *ppos)
{
char buf[32];
size_t buf_size;
buf[0] = 0;
buf_size = min(count, (sizeof(buf)-1));
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
switch (buf[0]) {
case 'y':
case 'Y':
case '1':
enable_tp_pid();
break;
case 'n':
case 'N':
case '0':
disable_tp_pid();
break;
}
return count;
}
static const struct file_operations fops_perftp = {
.read = read_enabled_perftp_file_bool,
.write = write_enabled_perftp_file_bool,
.llseek = default_llseek,
};
int __init init_tracecounters(void)
{
struct dentry *dir;
struct dentry *file;
unsigned int value = 1;
int cpu;
dir = debugfs_create_dir("perf_debug_tp", NULL);
if (!dir)
return -ENOMEM;
file = debugfs_create_file("enabled", 0660, dir,
&value, &fops_perftp);
if (!file) {
debugfs_remove(dir);
return -ENOMEM;
}
for_each_possible_cpu(cpu)
per_cpu(old_pid, cpu) = -1;
register_cpu_notifier(&tracectr_cpu_hotplug_notifier_block);
return 0;
}
int __exit exit_tracecounters(void)
{
unregister_cpu_notifier(&tracectr_cpu_hotplug_notifier_block);
return 0;
}
late_initcall(init_tracecounters);
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