Report that kernel is tainted if there was an OOPS
[linux-2.6.git] / arch / mips / kernel / mips-mt-fpaff.c
1 /*
2  * General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
3  * Copyright (C) 2005 Mips Technologies, Inc
4  */
5 #include <linux/cpu.h>
6 #include <linux/cpumask.h>
7 #include <linux/delay.h>
8 #include <linux/kernel.h>
9 #include <linux/init.h>
10 #include <linux/sched.h>
11 #include <linux/security.h>
12 #include <linux/types.h>
13 #include <asm/uaccess.h>
14
15 /*
16  * CPU mask used to set process affinity for MT VPEs/TCs with FPUs
17  */
18 cpumask_t mt_fpu_cpumask;
19
20 static int fpaff_threshold = -1;
21 unsigned long mt_fpemul_threshold = 0;
22
23 /*
24  * Replacement functions for the sys_sched_setaffinity() and
25  * sys_sched_getaffinity() system calls, so that we can integrate
26  * FPU affinity with the user's requested processor affinity.
27  * This code is 98% identical with the sys_sched_setaffinity()
28  * and sys_sched_getaffinity() system calls, and should be
29  * updated when kernel/sched.c changes.
30  */
31
32 /*
33  * find_process_by_pid - find a process with a matching PID value.
34  * used in sys_sched_set/getaffinity() in kernel/sched.c, so
35  * cloned here.
36  */
37 static inline struct task_struct *find_process_by_pid(pid_t pid)
38 {
39         return pid ? find_task_by_pid(pid) : current;
40 }
41
42
43 /*
44  * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
45  */
46 asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
47                                       unsigned long __user *user_mask_ptr)
48 {
49         cpumask_t new_mask;
50         cpumask_t effective_mask;
51         int retval;
52         struct task_struct *p;
53
54         if (len < sizeof(new_mask))
55                 return -EINVAL;
56
57         if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
58                 return -EFAULT;
59
60         lock_cpu_hotplug();
61         read_lock(&tasklist_lock);
62
63         p = find_process_by_pid(pid);
64         if (!p) {
65                 read_unlock(&tasklist_lock);
66                 unlock_cpu_hotplug();
67                 return -ESRCH;
68         }
69
70         /*
71          * It is not safe to call set_cpus_allowed with the
72          * tasklist_lock held.  We will bump the task_struct's
73          * usage count and drop tasklist_lock before invoking
74          * set_cpus_allowed.
75          */
76         get_task_struct(p);
77
78         retval = -EPERM;
79         if ((current->euid != p->euid) && (current->euid != p->uid) &&
80                         !capable(CAP_SYS_NICE)) {
81                 read_unlock(&tasklist_lock);
82                 goto out_unlock;
83         }
84
85         retval = security_task_setscheduler(p, 0, NULL);
86         if (retval)
87                 goto out_unlock;
88
89         /* Record new user-specified CPU set for future reference */
90         p->thread.user_cpus_allowed = new_mask;
91
92         /* Unlock the task list */
93         read_unlock(&tasklist_lock);
94
95         /* Compute new global allowed CPU set if necessary */
96         if ((p->thread.mflags & MF_FPUBOUND)
97         && cpus_intersects(new_mask, mt_fpu_cpumask)) {
98                 cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
99                 retval = set_cpus_allowed(p, effective_mask);
100         } else {
101                 p->thread.mflags &= ~MF_FPUBOUND;
102                 retval = set_cpus_allowed(p, new_mask);
103         }
104
105
106 out_unlock:
107         put_task_struct(p);
108         unlock_cpu_hotplug();
109         return retval;
110 }
111
112 /*
113  * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
114  */
115 asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
116                                       unsigned long __user *user_mask_ptr)
117 {
118         unsigned int real_len;
119         cpumask_t mask;
120         int retval;
121         struct task_struct *p;
122
123         real_len = sizeof(mask);
124         if (len < real_len)
125                 return -EINVAL;
126
127         lock_cpu_hotplug();
128         read_lock(&tasklist_lock);
129
130         retval = -ESRCH;
131         p = find_process_by_pid(pid);
132         if (!p)
133                 goto out_unlock;
134         retval = security_task_getscheduler(p);
135         if (retval)
136                 goto out_unlock;
137
138         cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
139
140 out_unlock:
141         read_unlock(&tasklist_lock);
142         unlock_cpu_hotplug();
143         if (retval)
144                 return retval;
145         if (copy_to_user(user_mask_ptr, &mask, real_len))
146                 return -EFAULT;
147         return real_len;
148 }
149
150
151 static int __init fpaff_thresh(char *str)
152 {
153         get_option(&str, &fpaff_threshold);
154         return 1;
155 }
156 __setup("fpaff=", fpaff_thresh);
157
158 /*
159  * FPU Use Factor empirically derived from experiments on 34K
160  */
161 #define FPUSEFACTOR 333
162
163 static __init int mt_fp_affinity_init(void)
164 {
165         if (fpaff_threshold >= 0) {
166                 mt_fpemul_threshold = fpaff_threshold;
167         } else {
168                 mt_fpemul_threshold =
169                         (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
170         }
171         printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n",
172                mt_fpemul_threshold);
173
174         return 0;
175 }
176 arch_initcall(mt_fp_affinity_init);