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// SPDX-License-Identifier: GPL-2.0
/*
* General MIPS MT support routines, usable in AP/SP and SMVP.
* Copyright (C) 2005 Mips Technologies, Inc
*/
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/cred.h>
#include <linux/security.h>
#include <linux/types.h>
#include <linux/uaccess.h>
/*
* CPU mask used to set process affinity for MT VPEs/TCs with FPUs
*/
cpumask_t mt_fpu_cpumask;
static int fpaff_threshold = -1;
unsigned long mt_fpemul_threshold;
/*
* Replacement functions for the sys_sched_setaffinity() and
* sys_sched_getaffinity() system calls, so that we can integrate
* FPU affinity with the user's requested processor affinity.
* This code is 98% identical with the sys_sched_setaffinity()
* and sys_sched_getaffinity() system calls, and should be
* updated when kernel/sched/core.c changes.
*/
/*
* find_process_by_pid - find a process with a matching PID value.
* used in sys_sched_set/getaffinity() in kernel/sched/core.c, so
* cloned here.
*/
static inline struct task_struct *find_process_by_pid(pid_t pid)
{
return pid ? find_task_by_vpid(pid) : current;
}
/*
* check the target process has a UID that matches the current process's
*/
static bool check_same_owner(struct task_struct *p)
{
const struct cred *cred = current_cred(), *pcred;
bool match;
rcu_read_lock();
pcred = __task_cred(p);
match = (uid_eq(cred->euid, pcred->euid) ||
uid_eq(cred->euid, pcred->uid));
rcu_read_unlock();
return match;
}
/*
* mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
*/
asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
unsigned long __user *user_mask_ptr)
{
cpumask_var_t cpus_allowed, new_mask, effective_mask;
struct thread_info *ti;
struct task_struct *p;
int retval;
if (len < sizeof(new_mask))
return -EINVAL;
if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
return -EFAULT;
get_online_cpus();
rcu_read_lock();
p = find_process_by_pid(pid);
if (!p) {
rcu_read_unlock();
put_online_cpus();
return -ESRCH;
}
/* Prevent p going away */
get_task_struct(p);
rcu_read_unlock();
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_put_task;
}
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_free_cpus_allowed;
}
if (!alloc_cpumask_var(&effective_mask, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_free_new_mask;
}
if (!check_same_owner(p) && !capable(CAP_SYS_NICE)) {
retval = -EPERM;
goto out_unlock;
}
retval = security_task_setscheduler(p);
if (retval)
goto out_unlock;
/* Record new user-specified CPU set for future reference */
cpumask_copy(&p->thread.user_cpus_allowed, new_mask);
again:
/* Compute new global allowed CPU set if necessary */
ti = task_thread_info(p);
if (test_ti_thread_flag(ti, TIF_FPUBOUND) &&
cpumask_intersects(new_mask, &mt_fpu_cpumask)) {
cpumask_and(effective_mask, new_mask, &mt_fpu_cpumask);
retval = set_cpus_allowed_ptr(p, effective_mask);
} else {
cpumask_copy(effective_mask, new_mask);
clear_ti_thread_flag(ti, TIF_FPUBOUND);
retval = set_cpus_allowed_ptr(p, new_mask);
}
if (!retval) {
cpuset_cpus_allowed(p, cpus_allowed);
if (!cpumask_subset(effective_mask, cpus_allowed)) {
/*
* We must have raced with a concurrent cpuset
* update. Just reset the cpus_allowed to the
* cpuset's cpus_allowed
*/
cpumask_copy(new_mask, cpus_allowed);
goto again;
}
}
out_unlock:
free_cpumask_var(effective_mask);
out_free_new_mask:
free_cpumask_var(new_mask);
out_free_cpus_allowed:
free_cpumask_var(cpus_allowed);
out_put_task:
put_task_struct(p);
put_online_cpus();
return retval;
}
/*
* mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
*/
asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
unsigned long __user *user_mask_ptr)
{
unsigned int real_len;
cpumask_t allowed, mask;
int retval;
struct task_struct *p;
real_len = sizeof(mask);
if (len < real_len)
return -EINVAL;
get_online_cpus();
read_lock(&tasklist_lock);
retval = -ESRCH;
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
cpumask_or(&allowed, &p->thread.user_cpus_allowed, p->cpus_ptr);
cpumask_and(&mask, &allowed, cpu_active_mask);
out_unlock:
read_unlock(&tasklist_lock);
put_online_cpus();
if (retval)
return retval;
if (copy_to_user(user_mask_ptr, &mask, real_len))
return -EFAULT;
return real_len;
}
static int __init fpaff_thresh(char *str)
{
get_option(&str, &fpaff_threshold);
return 1;
}
__setup("fpaff=", fpaff_thresh);
/*
* FPU Use Factor empirically derived from experiments on 34K
*/
#define FPUSEFACTOR 2000
static __init int mt_fp_affinity_init(void)
{
if (fpaff_threshold >= 0) {
mt_fpemul_threshold = fpaff_threshold;
} else {
mt_fpemul_threshold =
(FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
}
printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n",
mt_fpemul_threshold);
return 0;
}
arch_initcall(mt_fp_affinity_init);
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