// SPDX-License-Identifier: GPL-2.0
/*
* Implement CPU time clocks for the POSIX clock interface.
*/
#include <linux/sched/signal.h>
#include <linux/sched/cputime.h>
#include <linux/posix-timers.h>
#include <linux/errno.h>
#include <linux/math64.h>
#include <linux/uaccess.h>
#include <linux/kernel_stat.h>
#include <trace/events/timer.h>
#include <linux/tick.h>
#include <linux/workqueue.h>
#include <linux/compat.h>
#include <linux/sched/deadline.h>
#include <linux/task_work.h>
#include "posix-timers.h"
static void posix_cpu_timer_rearm(struct k_itimer *timer);
void posix_cputimers_group_init(struct posix_cputimers *pct, u64 cpu_limit)
{
posix_cputimers_init(pct);
if (cpu_limit != RLIM_INFINITY) {
pct->bases[CPUCLOCK_PROF].nextevt = cpu_limit * NSEC_PER_SEC;
pct->timers_active = true;
}
}
/*
* Called after updating RLIMIT_CPU to run cpu timer and update
* tsk->signal->posix_cputimers.bases[clock].nextevt expiration cache if
* necessary. Needs siglock protection since other code may update the
* expiration cache as well.
*
* Returns 0 on success, -ESRCH on failure. Can fail if the task is exiting and
* we cannot lock_task_sighand. Cannot fail if task is current.
*/
int update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
{
u64 nsecs = rlim_new * NSEC_PER_SEC;
unsigned long irq_fl;
if (!lock_task_sighand(task, &irq_fl))
return -ESRCH;
set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL);
unlock_task_sighand(task, &irq_fl);
return 0;
}
/*
* Functions for validating access to tasks.
*/
static struct pid *pid_for_clock(const clockid_t clock, bool gettime)
{
const bool thread = !!CPUCLOCK_PERTHREAD(clock);
const pid_t upid = CPUCLOCK_PID(clock);
struct pid *pid;
if (CPUCLOCK_WHICH(clock) >= CPUCLOCK_MAX)
return NULL;
/*
* If the encoded PID is 0, then the timer is targeted at current
* or the process to which current belongs.
*/
if (upid == 0)
return thread ? task_pid(current) : task_tgid(current);
pid = find_vpid(upid);
if (!pid)
return NULL;
if (thread) {
struct task_struct *tsk = pid_task(pid, PIDTYPE_PID);
return (tsk && same_thread_group(tsk, current)) ? pid : NULL;
}
/*
* For clock_gettime(PROCESS) allow finding the process by
* with the pid of the current task. The code needs the tgid
* of the process so that pid_task(pid, PIDTYPE_TGID) can be
* used to find the process.
*/
if (gettime && (pid == task_pid(current)))
return task_tgid(current);
/*
* For processes require that pid identifies a process.
*/
return pid_has_task(pid, PIDTYPE_TGID) ? pid : NULL;
}
static inline int validate_clock_permissions(const clockid_t clock)
{
int ret;
rcu_read_lock(
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