Commit | Line | Data |
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295cbf6d RB |
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; | |
982f6ffe | 21 | unsigned long mt_fpemul_threshold; |
295cbf6d RB |
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 | { | |
0e568536 | 39 | return pid ? find_task_by_vpid(pid) : current; |
295cbf6d RB |
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; | |
293c5bd1 | 53 | struct thread_info *ti; |
b4212737 | 54 | uid_t euid; |
295cbf6d RB |
55 | |
56 | if (len < sizeof(new_mask)) | |
57 | return -EINVAL; | |
58 | ||
59 | if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask))) | |
60 | return -EFAULT; | |
61 | ||
86ef5c9a | 62 | get_online_cpus(); |
295cbf6d RB |
63 | read_lock(&tasklist_lock); |
64 | ||
65 | p = find_process_by_pid(pid); | |
66 | if (!p) { | |
67 | read_unlock(&tasklist_lock); | |
86ef5c9a | 68 | put_online_cpus(); |
295cbf6d RB |
69 | return -ESRCH; |
70 | } | |
71 | ||
72 | /* | |
73 | * It is not safe to call set_cpus_allowed with the | |
74 | * tasklist_lock held. We will bump the task_struct's | |
75 | * usage count and drop tasklist_lock before invoking | |
76 | * set_cpus_allowed. | |
77 | */ | |
78 | get_task_struct(p); | |
79 | ||
b4212737 | 80 | euid = current_euid(); |
295cbf6d | 81 | retval = -EPERM; |
012703e0 RB |
82 | if (euid != p->cred->euid && euid != p->cred->uid && |
83 | !capable(CAP_SYS_NICE)) { | |
295cbf6d RB |
84 | read_unlock(&tasklist_lock); |
85 | goto out_unlock; | |
86 | } | |
87 | ||
88 | retval = security_task_setscheduler(p, 0, NULL); | |
89 | if (retval) | |
90 | goto out_unlock; | |
91 | ||
92 | /* Record new user-specified CPU set for future reference */ | |
93 | p->thread.user_cpus_allowed = new_mask; | |
94 | ||
95 | /* Unlock the task list */ | |
96 | read_unlock(&tasklist_lock); | |
97 | ||
98 | /* Compute new global allowed CPU set if necessary */ | |
293c5bd1 RB |
99 | ti = task_thread_info(p); |
100 | if (test_ti_thread_flag(ti, TIF_FPUBOUND) && | |
101 | cpus_intersects(new_mask, mt_fpu_cpumask)) { | |
295cbf6d RB |
102 | cpus_and(effective_mask, new_mask, mt_fpu_cpumask); |
103 | retval = set_cpus_allowed(p, effective_mask); | |
104 | } else { | |
293c5bd1 | 105 | clear_ti_thread_flag(ti, TIF_FPUBOUND); |
295cbf6d RB |
106 | retval = set_cpus_allowed(p, new_mask); |
107 | } | |
108 | ||
295cbf6d RB |
109 | out_unlock: |
110 | put_task_struct(p); | |
86ef5c9a | 111 | put_online_cpus(); |
295cbf6d RB |
112 | return retval; |
113 | } | |
114 | ||
115 | /* | |
116 | * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process | |
117 | */ | |
118 | asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, | |
119 | unsigned long __user *user_mask_ptr) | |
120 | { | |
121 | unsigned int real_len; | |
122 | cpumask_t mask; | |
123 | int retval; | |
124 | struct task_struct *p; | |
125 | ||
126 | real_len = sizeof(mask); | |
127 | if (len < real_len) | |
128 | return -EINVAL; | |
129 | ||
86ef5c9a | 130 | get_online_cpus(); |
295cbf6d RB |
131 | read_lock(&tasklist_lock); |
132 | ||
133 | retval = -ESRCH; | |
134 | p = find_process_by_pid(pid); | |
135 | if (!p) | |
136 | goto out_unlock; | |
137 | retval = security_task_getscheduler(p); | |
138 | if (retval) | |
139 | goto out_unlock; | |
140 | ||
141 | cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map); | |
142 | ||
143 | out_unlock: | |
144 | read_unlock(&tasklist_lock); | |
86ef5c9a | 145 | put_online_cpus(); |
295cbf6d RB |
146 | if (retval) |
147 | return retval; | |
148 | if (copy_to_user(user_mask_ptr, &mask, real_len)) | |
149 | return -EFAULT; | |
150 | return real_len; | |
151 | } | |
152 | ||
153 | ||
154 | static int __init fpaff_thresh(char *str) | |
155 | { | |
156 | get_option(&str, &fpaff_threshold); | |
157 | return 1; | |
158 | } | |
159 | __setup("fpaff=", fpaff_thresh); | |
160 | ||
161 | /* | |
162 | * FPU Use Factor empirically derived from experiments on 34K | |
163 | */ | |
9cc12363 | 164 | #define FPUSEFACTOR 2000 |
295cbf6d RB |
165 | |
166 | static __init int mt_fp_affinity_init(void) | |
167 | { | |
168 | if (fpaff_threshold >= 0) { | |
169 | mt_fpemul_threshold = fpaff_threshold; | |
170 | } else { | |
171 | mt_fpemul_threshold = | |
172 | (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ; | |
173 | } | |
174 | printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n", | |
175 | mt_fpemul_threshold); | |
176 | ||
177 | return 0; | |
178 | } | |
179 | arch_initcall(mt_fp_affinity_init); |