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 | #include <asm/syscalls.h> |
19 | |
20 | /* |
21 | * CPU mask used to set process affinity for MT VPEs/TCs with FPUs |
22 | */ |
23 | cpumask_t mt_fpu_cpumask; |
24 | |
25 | static int fpaff_threshold = -1; |
26 | unsigned long mt_fpemul_threshold; |
27 | |
28 | /* |
29 | * Replacement functions for the sys_sched_setaffinity() and |
30 | * sys_sched_getaffinity() system calls, so that we can integrate |
31 | * FPU affinity with the user's requested processor affinity. |
32 | * This code is 98% identical with the sys_sched_setaffinity() |
33 | * and sys_sched_getaffinity() system calls, and should be |
34 | * updated when kernel/sched/core.c changes. |
35 | */ |
36 | |
37 | /* |
38 | * find_process_by_pid - find a process with a matching PID value. |
39 | * used in sys_sched_set/getaffinity() in kernel/sched/core.c, so |
40 | * cloned here. |
41 | */ |
42 | static inline struct task_struct *find_process_by_pid(pid_t pid) |
43 | { |
44 | return pid ? find_task_by_vpid(nr: pid) : current; |
45 | } |
46 | |
47 | /* |
48 | * check the target process has a UID that matches the current process's |
49 | */ |
50 | static bool check_same_owner(struct task_struct *p) |
51 | { |
52 | const struct cred *cred = current_cred(), *pcred; |
53 | bool match; |
54 | |
55 | rcu_read_lock(); |
56 | pcred = __task_cred(p); |
57 | match = (uid_eq(left: cred->euid, right: pcred->euid) || |
58 | uid_eq(left: cred->euid, right: pcred->uid)); |
59 | rcu_read_unlock(); |
60 | return match; |
61 | } |
62 | |
63 | /* |
64 | * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process |
65 | */ |
66 | asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len, |
67 | unsigned long __user *user_mask_ptr) |
68 | { |
69 | cpumask_var_t cpus_allowed, new_mask, effective_mask; |
70 | struct thread_info *ti; |
71 | struct task_struct *p; |
72 | int retval; |
73 | |
74 | if (len < sizeof(new_mask)) |
75 | return -EINVAL; |
76 | |
77 | if (copy_from_user(to: &new_mask, from: user_mask_ptr, n: sizeof(new_mask))) |
78 | return -EFAULT; |
79 | |
80 | cpus_read_lock(); |
81 | rcu_read_lock(); |
82 | |
83 | p = find_process_by_pid(pid); |
84 | if (!p) { |
85 | rcu_read_unlock(); |
86 | cpus_read_unlock(); |
87 | return -ESRCH; |
88 | } |
89 | |
90 | /* Prevent p going away */ |
91 | get_task_struct(t: p); |
92 | rcu_read_unlock(); |
93 | |
94 | if (!alloc_cpumask_var(mask: &cpus_allowed, GFP_KERNEL)) { |
95 | retval = -ENOMEM; |
96 | goto out_put_task; |
97 | } |
98 | if (!alloc_cpumask_var(mask: &new_mask, GFP_KERNEL)) { |
99 | retval = -ENOMEM; |
100 | goto out_free_cpus_allowed; |
101 | } |
102 | if (!alloc_cpumask_var(mask: &effective_mask, GFP_KERNEL)) { |
103 | retval = -ENOMEM; |
104 | goto out_free_new_mask; |
105 | } |
106 | if (!check_same_owner(p) && !capable(CAP_SYS_NICE)) { |
107 | retval = -EPERM; |
108 | goto out_unlock; |
109 | } |
110 | |
111 | retval = security_task_setscheduler(p); |
112 | if (retval) |
113 | goto out_unlock; |
114 | |
115 | /* Record new user-specified CPU set for future reference */ |
116 | cpumask_copy(dstp: &p->thread.user_cpus_allowed, srcp: new_mask); |
117 | |
118 | again: |
119 | /* Compute new global allowed CPU set if necessary */ |
120 | ti = task_thread_info(p); |
121 | if (test_ti_thread_flag(ti, flag: TIF_FPUBOUND) && |
122 | cpumask_intersects(src1p: new_mask, src2p: &mt_fpu_cpumask)) { |
123 | cpumask_and(dstp: effective_mask, src1p: new_mask, src2p: &mt_fpu_cpumask); |
124 | retval = set_cpus_allowed_ptr(p, new_mask: effective_mask); |
125 | } else { |
126 | cpumask_copy(dstp: effective_mask, srcp: new_mask); |
127 | clear_ti_thread_flag(ti, flag: TIF_FPUBOUND); |
128 | retval = set_cpus_allowed_ptr(p, new_mask); |
129 | } |
130 | |
131 | if (!retval) { |
132 | cpuset_cpus_allowed(p, mask: cpus_allowed); |
133 | if (!cpumask_subset(src1p: effective_mask, src2p: cpus_allowed)) { |
134 | /* |
135 | * We must have raced with a concurrent cpuset |
136 | * update. Just reset the cpus_allowed to the |
137 | * cpuset's cpus_allowed |
138 | */ |
139 | cpumask_copy(dstp: new_mask, srcp: cpus_allowed); |
140 | goto again; |
141 | } |
142 | } |
143 | out_unlock: |
144 | free_cpumask_var(mask: effective_mask); |
145 | out_free_new_mask: |
146 | free_cpumask_var(mask: new_mask); |
147 | out_free_cpus_allowed: |
148 | free_cpumask_var(mask: cpus_allowed); |
149 | out_put_task: |
150 | put_task_struct(t: p); |
151 | cpus_read_unlock(); |
152 | return retval; |
153 | } |
154 | |
155 | /* |
156 | * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process |
157 | */ |
158 | asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, |
159 | unsigned long __user *user_mask_ptr) |
160 | { |
161 | unsigned int real_len; |
162 | cpumask_t allowed, mask; |
163 | int retval; |
164 | struct task_struct *p; |
165 | |
166 | real_len = sizeof(mask); |
167 | if (len < real_len) |
168 | return -EINVAL; |
169 | |
170 | cpus_read_lock(); |
171 | rcu_read_lock(); |
172 | |
173 | retval = -ESRCH; |
174 | p = find_process_by_pid(pid); |
175 | if (!p) |
176 | goto out_unlock; |
177 | retval = security_task_getscheduler(p); |
178 | if (retval) |
179 | goto out_unlock; |
180 | |
181 | cpumask_or(dstp: &allowed, src1p: &p->thread.user_cpus_allowed, src2p: p->cpus_ptr); |
182 | cpumask_and(dstp: &mask, src1p: &allowed, cpu_active_mask); |
183 | |
184 | out_unlock: |
185 | rcu_read_unlock(); |
186 | cpus_read_unlock(); |
187 | if (retval) |
188 | return retval; |
189 | if (copy_to_user(to: user_mask_ptr, from: &mask, n: real_len)) |
190 | return -EFAULT; |
191 | return real_len; |
192 | } |
193 | |
194 | |
195 | static int __init fpaff_thresh(char *str) |
196 | { |
197 | get_option(str: &str, pint: &fpaff_threshold); |
198 | return 1; |
199 | } |
200 | __setup("fpaff=" , fpaff_thresh); |
201 | |
202 | /* |
203 | * FPU Use Factor empirically derived from experiments on 34K |
204 | */ |
205 | #define FPUSEFACTOR 2000 |
206 | |
207 | static __init int mt_fp_affinity_init(void) |
208 | { |
209 | if (fpaff_threshold >= 0) { |
210 | mt_fpemul_threshold = fpaff_threshold; |
211 | } else { |
212 | mt_fpemul_threshold = |
213 | (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ; |
214 | } |
215 | printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n" , |
216 | mt_fpemul_threshold); |
217 | |
218 | return 0; |
219 | } |
220 | arch_initcall(mt_fp_affinity_init); |
221 | |