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/*
* General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
* Copyright (C) 2005 Mips Technologies, Inc
*/
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/types.h>
#include <asm/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 = 0;
/*
* 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.c changes.
*/
/*
* find_process_by_pid - find a process with a matching PID value.
* used in sys_sched_set/getaffinity() in kernel/sched.c, so
* cloned here.
*/
static inline struct task_struct *find_process_by_pid(pid_t pid)
{
return pid ? find_task_by_vpid(pid) : current;
}
/*
* 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_t new_mask;
cpumask_t effective_mask;
int retval;
struct task_struct *p;
struct thread_info *ti;
uid_t euid;
if (len < sizeof(new_mask))
return -EINVAL;
if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
return -EFAULT;
get_online_cpus();
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
put_online_cpus();
return -ESRCH;
}
/*
* It is not safe to call set_cpus_allowed with the
* tasklist_lock held. We will bump the task_struct's
* usage count and drop tasklist_lock before invoking
* set_cpus_allowed.
*/
get_task_struct(p);
euid = current_euid();
retval = -EPERM;
if (euid != p->euid && euid != p->uid && !capable(CAP_SYS_NICE)) {
read_unlock(&tasklist_lock);
goto out_unlock;
}
retval = security_task_setscheduler(p, 0, NULL);
if (retval)
goto out_unlock;
/* Record new user-specified CPU set for future reference */
p->thread.user_cpus_allowed = new_mask;
/* Unlock the task list */
read_unlock(&tasklist_lock);
/* Compute new global allowed CPU set if necessary */
ti = task_thread_info(p);
if (test_ti_thread_flag(ti, TIF_FPUBOUND) &&
cpus_intersects(new_mask, mt_fpu_cpumask)) {
cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
retval = set_cpus_allowed(p, effective_mask);
} else {
clear_ti_thread_flag(ti, TIF_FPUBOUND);
retval = set_cpus_allowed(p, new_mask);
}
out_unlock:
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 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;
cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
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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