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 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 ts->group_leader = ts; 71 atomic_set(&ts->usage, 1); 72 atomic_set(&ts->state, TASK_RUNNING); 73 init_completion(&ts->parked); 74 init_completion(&ts->exited); 75 76 proc = td->td_proc; 77 78 /* check if another thread already has a mm_struct */ 79 PROC_LOCK(proc); 80 FOREACH_THREAD_IN_PROC(proc, td_other) { 81 ts_other = td_other->td_lkpi_task; 82 if (ts_other == NULL) 83 continue; 84 85 mm_other = ts_other->mm; 86 if (mm_other == NULL) 87 continue; 88 89 /* try to share other mm_struct */ 90 if (atomic_inc_not_zero(&mm_other->mm_users)) { 91 /* set mm_struct pointer */ 92 ts->mm = mm_other; 93 break; 94 } 95 } 96 97 /* use allocated mm_struct as a fallback */ 98 if (ts->mm == NULL) { 99 /* setup new mm_struct */ 100 init_rwsem(&mm->mmap_sem); 101 atomic_set(&mm->mm_count, 1); 102 atomic_set(&mm->mm_users, 1); 103 /* set mm_struct pointer */ 104 ts->mm = mm; 105 /* clear pointer to not free memory */ 106 mm = NULL; 107 } 108 109 /* store pointer to task struct */ 110 td->td_lkpi_task = ts; 111 PROC_UNLOCK(proc); 112 113 /* free mm_struct pointer, if any */ 114 free(mm, M_LINUX_CURRENT); 115 116 return (0); 117 } 118 119 struct mm_struct * 120 linux_get_task_mm(struct task_struct *task) 121 { 122 struct mm_struct *mm; 123 124 mm = task->mm; 125 if (mm != NULL) { 126 atomic_inc(&mm->mm_users); 127 return (mm); 128 } 129 return (NULL); 130 } 131 132 void 133 linux_mm_dtor(struct mm_struct *mm) 134 { 135 free(mm, M_LINUX_CURRENT); 136 } 137 138 void 139 linux_free_current(struct task_struct *ts) 140 { 141 mmput(ts->mm); 142 free(ts, M_LINUX_CURRENT); 143 } 144 145 static void 146 linuxkpi_thread_dtor(void *arg __unused, struct thread *td) 147 { 148 struct task_struct *ts; 149 150 ts = td->td_lkpi_task; 151 if (ts == NULL) 152 return; 153 154 td->td_lkpi_task = NULL; 155 put_task_struct(ts); 156 } 157 158 static struct task_struct * 159 linux_get_pid_task_int(pid_t pid, const bool do_get) 160 { 161 struct thread *td; 162 struct proc *p; 163 struct task_struct *ts; 164 165 if (pid > PID_MAX) { 166 /* try to find corresponding thread */ 167 td = tdfind(pid, -1); 168 if (td != NULL) { 169 ts = td->td_lkpi_task; 170 if (do_get && ts != NULL) 171 get_task_struct(ts); 172 PROC_UNLOCK(td->td_proc); 173 return (ts); 174 } 175 } else { 176 /* try to find corresponding procedure */ 177 p = pfind(pid); 178 if (p != NULL) { 179 FOREACH_THREAD_IN_PROC(p, td) { 180 ts = td->td_lkpi_task; 181 if (ts != NULL) { 182 if (do_get) 183 get_task_struct(ts); 184 PROC_UNLOCK(p); 185 return (ts); 186 } 187 } 188 PROC_UNLOCK(p); 189 } 190 } 191 return (NULL); 192 } 193 194 struct task_struct * 195 linux_pid_task(pid_t pid) 196 { 197 return (linux_get_pid_task_int(pid, false)); 198 } 199 200 struct task_struct * 201 linux_get_pid_task(pid_t pid) 202 { 203 return (linux_get_pid_task_int(pid, true)); 204 } 205 206 bool 207 linux_task_exiting(struct task_struct *task) 208 { 209 struct thread *td; 210 struct proc *p; 211 bool ret; 212 213 ret = false; 214 215 /* try to find corresponding thread */ 216 td = tdfind(task->pid, -1); 217 if (td != NULL) { 218 p = td->td_proc; 219 } else { 220 /* try to find corresponding procedure */ 221 p = pfind(task->pid); 222 } 223 224 if (p != NULL) { 225 if ((p->p_flag & P_WEXIT) != 0) 226 ret = true; 227 PROC_UNLOCK(p); 228 } 229 return (ret); 230 } 231 232 static void 233 linux_current_init(void *arg __unused) 234 { 235 lkpi_alloc_current = linux_alloc_current; 236 linuxkpi_thread_dtor_tag = EVENTHANDLER_REGISTER(thread_dtor, 237 linuxkpi_thread_dtor, NULL, EVENTHANDLER_PRI_ANY); 238 } 239 SYSINIT(linux_current, SI_SUB_EVENTHANDLER, SI_ORDER_SECOND, linux_current_init, NULL); 240 241 static void 242 linux_current_uninit(void *arg __unused) 243 { 244 struct proc *p; 245 struct task_struct *ts; 246 struct thread *td; 247 248 sx_slock(&allproc_lock); 249 FOREACH_PROC_IN_SYSTEM(p) { 250 PROC_LOCK(p); 251 FOREACH_THREAD_IN_PROC(p, td) { 252 if ((ts = td->td_lkpi_task) != NULL) { 253 td->td_lkpi_task = NULL; 254 put_task_struct(ts); 255 } 256 } 257 PROC_UNLOCK(p); 258 } 259 sx_sunlock(&allproc_lock); 260 EVENTHANDLER_DEREGISTER(thread_dtor, linuxkpi_thread_dtor_tag); 261 lkpi_alloc_current = linux_alloc_current_noop; 262 } 263 SYSUNINIT(linux_current, SI_SUB_EVENTHANDLER, SI_ORDER_SECOND, linux_current_uninit, NULL); 264