1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * General MIPS MT support routines, usable in AP/SP and SMVP. |
4 | * Copyright (C) 2005 Mips Technologies, Inc |
5 | */ |
6 | #include <linux/cpu.h> |
7 | #include <linux/cpuset.h> |
8 | #include <linux/cpumask.h> |
9 | #include <linux/delay.h> |
10 | #include <linux/kernel.h> |
11 | #include <linux/init.h> |
12 | #include <linux/sched.h> |
13 | #include <linux/sched/task.h> |
14 | #include <linux/cred.h> |
15 | #include <linux/security.h> |
16 | #include <linux/types.h> |
17 | #include <linux/uaccess.h> |
18 | |
19 | /* |
20 | * CPU mask used to set process affinity for MT VPEs/TCs with FPUs |
21 | */ |
22 | cpumask_t mt_fpu_cpumask; |
23 | |
24 | static int fpaff_threshold = -1; |
25 | unsigned long mt_fpemul_threshold; |
26 | |
27 | /* |
28 | * Replacement functions for the sys_sched_setaffinity() and |
29 | * sys_sched_getaffinity() system calls, so that we can integrate |
30 | * FPU affinity with the user's requested processor affinity. |
31 | * This code is 98% identical with the sys_sched_setaffinity() |
32 | * and sys_sched_getaffinity() system calls, and should be |
33 | * updated when kernel/sched/core.c changes. |
34 | */ |
35 | |
36 | /* |
37 | * find_process_by_pid - find a process with a matching PID value. |
38 | * used in sys_sched_set/getaffinity() in kernel/sched/core.c, so |
39 | * cloned here. |
40 | */ |
41 | static inline struct task_struct *find_process_by_pid(pid_t pid) |
42 | { |
43 | return pid ? find_task_by_vpid(nr: pid) : current; |
44 | } |
45 | |
46 | /* |
47 | * check the target process has a UID that matches the current process's |
48 | */ |
49 | static bool check_same_owner(struct task_struct *p) |
50 | { |
51 | const struct cred *cred = current_cred(), *pcred; |
52 | bool match; |
53 | |
54 | rcu_read_lock(); |
55 | pcred = __task_cred(p); |
56 | match = (uid_eq(left: cred->euid, right: pcred->euid) || |
57 | uid_eq(left: cred->euid, right: pcred->uid)); |
58 | rcu_read_unlock(); |
59 | return match; |
60 | } |
61 | |
62 | /* |
63 | * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process |
64 | */ |
65 | asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len, |
66 | unsigned long __user *user_mask_ptr) |
67 | { |
68 | cpumask_var_t cpus_allowed, new_mask, effective_mask; |
69 | struct thread_info *ti; |
70 | struct task_struct *p; |
71 | int retval; |
72 | |
73 | if (len < sizeof(new_mask)) |
74 | return -EINVAL; |
75 | |
76 | if (copy_from_user(to: &new_mask, from: user_mask_ptr, n: sizeof(new_mask))) |
77 | return -EFAULT; |
78 | |
79 | cpus_read_lock(); |
80 | rcu_read_lock(); |
81 | |
82 | p = find_process_by_pid(pid); |
83 | if (!p) { |
84 | rcu_read_unlock(); |
85 | cpus_read_unlock(); |
86 | return -ESRCH; |
87 | } |
88 | |
89 | /* Prevent p going away */ |
90 | get_task_struct(t: p); |
91 | rcu_read_unlock(); |
92 | |
93 | if (!alloc_cpumask_var(mask: &cpus_allowed, GFP_KERNEL)) { |
94 | retval = -ENOMEM; |
95 | goto out_put_task; |
96 | } |
97 | if (!alloc_cpumask_var(mask: &new_mask, GFP_KERNEL)) { |
98 | retval = -ENOMEM; |
99 | goto out_free_cpus_allowed; |
100 | } |
101 | if (!alloc_cpumask_var(mask: &effective_mask, GFP_KERNEL)) { |
102 | retval = -ENOMEM; |
103 | goto out_free_new_mask; |
104 | } |
105 | if (!check_same_owner(p) && !capable(CAP_SYS_NICE)) { |
106 | retval = -EPERM; |
107 | goto out_unlock; |
108 | } |
109 | |
110 | retval = security_task_setscheduler(p); |
111 | if (retval) |
112 | goto out_unlock; |
113 | |
114 | /* Record new user-specified CPU set for future reference */ |
115 | cpumask_copy(dstp: &p->thread.user_cpus_allowed, srcp: new_mask); |
116 | |
117 | again: |
118 | /* Compute new global allowed CPU set if necessary */ |
119 | ti = task_thread_info(p); |
120 | if (test_ti_thread_flag(ti, flag: TIF_FPUBOUND) && |
121 | cpumask_intersects(src1p: new_mask, src2p: &mt_fpu_cpumask)) { |
122 | cpumask_and(dstp: effective_mask, src1p: new_mask, src2p: &mt_fpu_cpumask); |
123 | retval = set_cpus_allowed_ptr(p, new_mask: effective_mask); |
124 | } else { |
125 | cpumask_copy(dstp: effective_mask, srcp: new_mask); |
126 | clear_ti_thread_flag(ti, flag: TIF_FPUBOUND); |
127 | retval = set_cpus_allowed_ptr(p, new_mask); |
128 | } |
129 | |
130 | if (!retval) { |
131 | cpuset_cpus_allowed(p, mask: cpus_allowed); |
132 | if (!cpumask_subset(src1p: effective_mask, src2p: cpus_allowed)) { |
133 | /* |
134 | * We must have raced with a concurrent cpuset |
135 | * update. Just reset the cpus_allowed to the |
136 | * cpuset's cpus_allowed |
137 | */ |
138 | cpumask_copy(dstp: new_mask, srcp: cpus_allowed); |
139 | goto again; |
140 | } |
141 | } |
142 | out_unlock: |
143 | free_cpumask_var(mask: effective_mask); |
144 | out_free_new_mask: |
145 | free_cpumask_var(mask: new_mask); |
146 | out_free_cpus_allowed: |
147 | free_cpumask_var(mask: cpus_allowed); |
148 | out_put_task: |
149 | put_task_struct(t: p); |
150 | cpus_read_unlock(); |
151 | return retval; |
152 | } |
153 | |
154 | /* |
155 | * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process |
156 | */ |
157 | asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, |
158 | unsigned long __user *user_mask_ptr) |
159 | { |
160 | unsigned int real_len; |
161 | cpumask_t allowed, mask; |
162 | int retval; |
163 | struct task_struct *p; |
164 | |
165 | real_len = sizeof(mask); |
166 | if (len < real_len) |
167 | return -EINVAL; |
168 | |
169 | cpus_read_lock(); |
170 | rcu_read_lock(); |
171 | |
172 | retval = -ESRCH; |
173 | p = find_process_by_pid(pid); |
174 | if (!p) |
175 | goto out_unlock; |
176 | retval = security_task_getscheduler(p); |
177 | if (retval) |
178 | goto out_unlock; |
179 | |
180 | cpumask_or(dstp: &allowed, src1p: &p->thread.user_cpus_allowed, src2p: p->cpus_ptr); |
181 | cpumask_and(dstp: &mask, src1p: &allowed, cpu_active_mask); |
182 | |
183 | out_unlock: |
184 | rcu_read_unlock(); |
185 | cpus_read_unlock(); |
186 | if (retval) |
187 | return retval; |
188 | if (copy_to_user(to: user_mask_ptr, from: &mask, n: real_len)) |
189 | return -EFAULT; |
190 | return real_len; |
191 | } |
192 | |
193 | |
194 | static int __init fpaff_thresh(char *str) |
195 | { |
196 | get_option(str: &str, pint: &fpaff_threshold); |
197 | return 1; |
198 | } |
199 | __setup("fpaff=" , fpaff_thresh); |
200 | |
201 | /* |
202 | * FPU Use Factor empirically derived from experiments on 34K |
203 | */ |
204 | #define FPUSEFACTOR 2000 |
205 | |
206 | static __init int mt_fp_affinity_init(void) |
207 | { |
208 | if (fpaff_threshold >= 0) { |
209 | mt_fpemul_threshold = fpaff_threshold; |
210 | } else { |
211 | mt_fpemul_threshold = |
212 | (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ; |
213 | } |
214 | printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n" , |
215 | mt_fpemul_threshold); |
216 | |
217 | return 0; |
218 | } |
219 | arch_initcall(mt_fp_affinity_init); |
220 | |