1 /*-
2 * Copyright (c) 2017 Hans Petter Selasky
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 #include <linux/compat.h>
31 #include <linux/completion.h>
32 #include <linux/mm.h>
33 #include <linux/kthread.h>
34
35 #include <sys/kernel.h>
36 #include <sys/eventhandler.h>
37 #include <sys/malloc.h>
38
39 static eventhandler_tag linuxkpi_thread_dtor_tag;
40
41 static MALLOC_DEFINE(M_LINUX_CURRENT, "linuxcurrent", "LinuxKPI task structure");
42
43 int
linux_alloc_current(struct thread * td,int flags)44 linux_alloc_current(struct thread *td, int flags)
45 {
46 struct proc *proc;
47 struct thread *td_other;
48 struct task_struct *ts;
49 struct task_struct *ts_other;
50 struct mm_struct *mm;
51 struct mm_struct *mm_other;
52
53 MPASS(td->td_lkpi_task == NULL);
54
55 ts = malloc(sizeof(*ts), M_LINUX_CURRENT, flags | M_ZERO);
56 if (ts == NULL)
57 return (ENOMEM);
58
59 mm = malloc(sizeof(*mm), M_LINUX_CURRENT, flags | M_ZERO);
60 if (mm == NULL) {
61 free(ts, M_LINUX_CURRENT);
62 return (ENOMEM);
63 }
64
65 /* setup new task structure */
66 atomic_set(&ts->kthread_flags, 0);
67 ts->task_thread = td;
68 ts->comm = td->td_name;
69 ts->pid = td->td_tid;
70 atomic_set(&ts->usage, 1);
71 atomic_set(&ts->state, TASK_RUNNING);
72 init_completion(&ts->parked);
73 init_completion(&ts->exited);
74
75 proc = td->td_proc;
76
77 /* check if another thread already has a mm_struct */
78 PROC_LOCK(proc);
79 FOREACH_THREAD_IN_PROC(proc, td_other) {
80 ts_other = td_other->td_lkpi_task;
81 if (ts_other == NULL)
82 continue;
83
84 mm_other = ts_other->mm;
85 if (mm_other == NULL)
86 continue;
87
88 /* try to share other mm_struct */
89 if (atomic_inc_not_zero(&mm_other->mm_users)) {
90 /* set mm_struct pointer */
91 ts->mm = mm_other;
92 break;
93 }
94 }
95
96 /* use allocated mm_struct as a fallback */
97 if (ts->mm == NULL) {
98 /* setup new mm_struct */
99 init_rwsem(&mm->mmap_sem);
100 atomic_set(&mm->mm_count, 1);
101 atomic_set(&mm->mm_users, 1);
102 /* set mm_struct pointer */
103 ts->mm = mm;
104 /* clear pointer to not free memory */
105 mm = NULL;
106 }
107
108 /* store pointer to task struct */
109 td->td_lkpi_task = ts;
110 PROC_UNLOCK(proc);
111
112 /* free mm_struct pointer, if any */
113 free(mm, M_LINUX_CURRENT);
114
115 return (0);
116 }
117
118 struct mm_struct *
linux_get_task_mm(struct task_struct * task)119 linux_get_task_mm(struct task_struct *task)
120 {
121 struct mm_struct *mm;
122
123 mm = task->mm;
124 if (mm != NULL) {
125 atomic_inc(&mm->mm_users);
126 return (mm);
127 }
128 return (NULL);
129 }
130
131 void
linux_mm_dtor(struct mm_struct * mm)132 linux_mm_dtor(struct mm_struct *mm)
133 {
134 free(mm, M_LINUX_CURRENT);
135 }
136
137 void
linux_free_current(struct task_struct * ts)138 linux_free_current(struct task_struct *ts)
139 {
140 mmput(ts->mm);
141 free(ts, M_LINUX_CURRENT);
142 }
143
144 static void
linuxkpi_thread_dtor(void * arg __unused,struct thread * td)145 linuxkpi_thread_dtor(void *arg __unused, struct thread *td)
146 {
147 struct task_struct *ts;
148
149 ts = td->td_lkpi_task;
150 if (ts == NULL)
151 return;
152
153 td->td_lkpi_task = NULL;
154 put_task_struct(ts);
155 }
156
157 struct task_struct *
linux_pid_task(pid_t pid)158 linux_pid_task(pid_t pid)
159 {
160 struct thread *td;
161 struct proc *p;
162
163 /* try to find corresponding thread */
164 td = tdfind(pid, -1);
165 if (td != NULL) {
166 struct task_struct *ts = td->td_lkpi_task;
167 PROC_UNLOCK(td->td_proc);
168 return (ts);
169 }
170
171 /* try to find corresponding procedure */
172 p = pfind(pid);
173 if (p != NULL) {
174 FOREACH_THREAD_IN_PROC(p, td) {
175 struct task_struct *ts = td->td_lkpi_task;
176 if (ts != NULL) {
177 PROC_UNLOCK(p);
178 return (ts);
179 }
180 }
181 PROC_UNLOCK(p);
182 }
183 return (NULL);
184 }
185
186 struct task_struct *
linux_get_pid_task(pid_t pid)187 linux_get_pid_task(pid_t pid)
188 {
189 struct thread *td;
190 struct proc *p;
191
192 /* try to find corresponding thread */
193 td = tdfind(pid, -1);
194 if (td != NULL) {
195 struct task_struct *ts = td->td_lkpi_task;
196 if (ts != NULL)
197 get_task_struct(ts);
198 PROC_UNLOCK(td->td_proc);
199 return (ts);
200 }
201
202 /* try to find corresponding procedure */
203 p = pfind(pid);
204 if (p != NULL) {
205 FOREACH_THREAD_IN_PROC(p, td) {
206 struct task_struct *ts = td->td_lkpi_task;
207 if (ts != NULL) {
208 get_task_struct(ts);
209 PROC_UNLOCK(p);
210 return (ts);
211 }
212 }
213 PROC_UNLOCK(p);
214 }
215 return (NULL);
216 }
217
218 bool
linux_task_exiting(struct task_struct * task)219 linux_task_exiting(struct task_struct *task)
220 {
221 struct thread *td;
222 struct proc *p;
223 bool ret;
224
225 ret = false;
226
227 /* try to find corresponding thread */
228 td = tdfind(task->pid, -1);
229 if (td != NULL) {
230 p = td->td_proc;
231 } else {
232 /* try to find corresponding procedure */
233 p = pfind(task->pid);
234 }
235
236 if (p != NULL) {
237 if ((p->p_flag & P_WEXIT) != 0)
238 ret = true;
239 PROC_UNLOCK(p);
240 }
241 return (ret);
242 }
243
244 static void
linux_current_init(void * arg __unused)245 linux_current_init(void *arg __unused)
246 {
247 linuxkpi_thread_dtor_tag = EVENTHANDLER_REGISTER(thread_dtor,
248 linuxkpi_thread_dtor, NULL, EVENTHANDLER_PRI_ANY);
249 }
250 SYSINIT(linux_current, SI_SUB_EVENTHANDLER, SI_ORDER_SECOND, linux_current_init, NULL);
251
252 static void
linux_current_uninit(void * arg __unused)253 linux_current_uninit(void *arg __unused)
254 {
255 struct proc *p;
256 struct task_struct *ts;
257 struct thread *td;
258
259 sx_slock(&allproc_lock);
260 FOREACH_PROC_IN_SYSTEM(p) {
261 PROC_LOCK(p);
262 FOREACH_THREAD_IN_PROC(p, td) {
263 if ((ts = td->td_lkpi_task) != NULL) {
264 td->td_lkpi_task = NULL;
265 put_task_struct(ts);
266 }
267 }
268 PROC_UNLOCK(p);
269 }
270 sx_sunlock(&allproc_lock);
271
272 EVENTHANDLER_DEREGISTER(thread_dtor, linuxkpi_thread_dtor_tag);
273 }
274 SYSUNINIT(linux_current, SI_SUB_EVENTHANDLER, SI_ORDER_SECOND, linux_current_uninit, NULL);
275