osfmk/kern/work_interval.c

   1 /*
   2  * Copyright (c) 2017 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29
  30 #include <sys/work_interval.h>
  31
  32 #include <kern/work_interval.h>
  33
  34 #include <kern/thread.h>
  35 #include <kern/sched_prim.h>
  36 #include <kern/machine.h>
  37 #include <kern/thread_group.h>
  38 #include <kern/ipc_kobject.h>
  39 #include <kern/task.h>
  40 #include <kern/coalition.h>
  41 #include <kern/policy_internal.h>
  42
  43 #include <mach/kern_return.h>
  44 #include <mach/notify.h>
  45
  46 #include <stdatomic.h>
  47
  48 /*
  49  * Work Interval structs
  50  *
  51  * This struct represents a thread group and/or work interval context
  52  * in a mechanism that is represented with a kobject.
  53  *
  54  * Every thread that has joined a WI has a +1 ref, and the port
  55  * has a +1 ref as well.
  56  *
  57  * TODO: groups need to have a 'is for WI' flag
  58  *      and they need a flag to create that says 'for WI'
  59  *      This would allow CLPC to avoid allocating WI support
  60  *      data unless it is needed
  61  *
  62  * TODO: Enforce not having more than one non-group joinable work
  63  *      interval per thread group.
  64  *      CLPC only wants to see one WI-notify callout per group.
  65  */
  66
  67 struct work_interval {
  68         uint64_t wi_id;
  69         _Atomic uint32_t wi_ref_count;
  70         uint32_t wi_create_flags;
  71
  72         /* for debugging purposes only, does not hold a ref on port */
  73         ipc_port_t wi_port;
  74
  75         /*
  76          * holds uniqueid and version of creating process,
  77          * used to permission-gate notify
  78          * TODO: you'd think there would be a better way to do this
  79          */
  80         uint64_t wi_creator_uniqueid;
  81         uint32_t wi_creator_pid;
  82         int wi_creator_pidversion;
  83
  84 };
  85
  86 static inline void
  87 wi_retain(struct work_interval *work_interval)
  88 {
  89         uint32_t old_count;
  90         old_count = atomic_fetch_add_explicit(&work_interval->wi_ref_count,
  91                                               1, memory_order_relaxed);
  92         assert(old_count > 0);
  93 }
  94
  95 static inline void
  96 wi_release(struct work_interval *work_interval)
  97 {
  98         uint32_t old_count;
  99         old_count = atomic_fetch_sub_explicit(&work_interval->wi_ref_count,
 100                                               1, memory_order_relaxed);
 101         assert(old_count > 0);
 102
 103         if (old_count == 1) {
 104
 105
 106                 kfree(work_interval, sizeof(struct work_interval));
 107         }
 108 }
 109
 110 /*
 111  * work_interval_port_alloc
 112  *
 113  * Description: Obtain a send right for the given work interval struct.
 114  *
 115  * Parameters:  work_interval - A work_interval struct
 116  *              Consumes a +1 ref count on work_interval, now owned by the port.
 117  *
 118  * Returns:     Port of type IKOT_WORK_INTERVAL with work_interval set as its kobject.
 119  *              Returned with a +1 send right and no-senders notification armed.
 120  *              Work interval struct reference is held by the port.
 121  */
 122 static ipc_port_t
 123 work_interval_port_alloc(struct work_interval *work_interval)
 124 {
 125         ipc_port_t work_interval_port = ipc_port_alloc_kernel();
 126
 127         if (work_interval_port == IP_NULL)
 128                 panic("failed to allocate work interval port");
 129
 130         assert(work_interval->wi_port == IP_NULL);
 131
 132         ip_lock(work_interval_port);
 133         ipc_kobject_set_atomically(work_interval_port, (ipc_kobject_t)work_interval,
 134                                    IKOT_WORK_INTERVAL);
 135
 136         ipc_port_t notify_port = ipc_port_make_sonce_locked(work_interval_port);
 137         ipc_port_t old_notify_port = IP_NULL;
 138         ipc_port_nsrequest(work_interval_port, 1, notify_port, &old_notify_port);
 139         /* port unlocked */
 140
 141         assert(old_notify_port == IP_NULL);
 142
 143         /* This is the only make-send that will happen on this port */
 144         ipc_port_t send_port = ipc_port_make_send(work_interval_port);
 145         assert(IP_VALID(send_port));
 146
 147         work_interval->wi_port = work_interval_port;
 148
 149         return send_port;
 150 }
 151
 152 /*
 153  * work_interval_port_convert
 154  *
 155  * Called with port locked, returns reference to work interval
 156  * if indeed the port is a work interval kobject port
 157  */
 158 static struct work_interval *
 159 work_interval_port_convert_locked(ipc_port_t port)
 160 {
 161         struct work_interval *work_interval = NULL;
 162
 163         if (!IP_VALID(port))
 164                 return NULL;
 165
 166         if (!ip_active(port))
 167                 return NULL;
 168
 169         if (IKOT_WORK_INTERVAL != ip_kotype(port))
 170                 return NULL;
 171
 172         work_interval = (struct work_interval *)port->ip_kobject;
 173
 174         wi_retain(work_interval);
 175
 176         return work_interval;
 177 }
 178
 179 /*
 180  * port_name_to_work_interval
 181  *
 182  * Description: Obtain a reference to the work_interval associated with a given port.
 183  *
 184  * Parameters:  name    A Mach port name to translate.
 185  *
 186  * Returns:     NULL    The given Mach port did not reference a work_interval.
 187  *              !NULL   The work_interval that is associated with the Mach port.
 188  */
 189 static kern_return_t
 190 port_name_to_work_interval(mach_port_name_t     name,
 191                            struct work_interval **work_interval)
 192 {
 193         if (!MACH_PORT_VALID(name))
 194                 return KERN_INVALID_NAME;
 195
 196         ipc_port_t port = IPC_PORT_NULL;
 197         kern_return_t kr = KERN_SUCCESS;
 198
 199         kr = ipc_port_translate_send(current_space(), name, &port);
 200         if (kr != KERN_SUCCESS)
 201                 return kr;
 202         /* port is locked */
 203
 204         assert(IP_VALID(port));
 205
 206         struct work_interval *converted_work_interval;
 207
 208         converted_work_interval = work_interval_port_convert_locked(port);
 209
 210         /* the port is valid, but doesn't denote a work_interval */
 211         if (converted_work_interval == NULL)
 212                 kr = KERN_INVALID_CAPABILITY;
 213
 214         ip_unlock(port);
 215
 216         if (kr == KERN_SUCCESS)
 217                 *work_interval = converted_work_interval;
 218
 219         return kr;
 220
 221 }
 222
 223
 224 /*
 225  * work_interval_port_notify
 226  *
 227  * Description: Handle a no-senders notification for a work interval port.
 228  *              Destroys the port and releases its reference on the work interval.
 229  *
 230  * Parameters:  msg     A Mach no-senders notification message.
 231  *
 232  * Note: This assumes that there is only one create-right-from-work-interval point,
 233  *       if the ability to extract another send right after creation is added,
 234  *       this will have to change to handle make-send counts correctly.
 235  */
 236 void
 237 work_interval_port_notify(mach_msg_header_t *msg)
 238 {
 239         mach_no_senders_notification_t *notification = (void *)msg;
 240         ipc_port_t port = notification->not_header.msgh_remote_port;
 241         struct work_interval *work_interval = NULL;
 242
 243         if (!IP_VALID(port))
 244                 panic("work_interval_port_notify(): invalid port");
 245
 246         ip_lock(port);
 247
 248         if (!ip_active(port))
 249                 panic("work_interval_port_notify(): inactive port %p", port);
 250
 251         if (ip_kotype(port) != IKOT_WORK_INTERVAL)
 252                 panic("work_interval_port_notify(): not the right kobject: %p, %d\n",
 253                       port, ip_kotype(port));
 254
 255         if (port->ip_mscount != notification->not_count)
 256                 panic("work_interval_port_notify(): unexpected make-send count: %p, %d, %d",
 257                       port, port->ip_mscount, notification->not_count);
 258
 259         if (port->ip_srights != 0)
 260                 panic("work_interval_port_notify(): unexpected send right count: %p, %d",
 261                       port, port->ip_srights);
 262
 263         work_interval = (struct work_interval *)port->ip_kobject;
 264
 265         if (work_interval == NULL)
 266                 panic("work_interval_port_notify(): missing kobject: %p", port);
 267
 268         ipc_kobject_set_atomically(port, IKO_NULL, IKOT_NONE);
 269
 270         work_interval->wi_port = MACH_PORT_NULL;
 271
 272         ip_unlock(port);
 273
 274         ipc_port_dealloc_kernel(port);
 275         wi_release(work_interval);
 276 }
 277
 278 /*
 279  * Change thread's bound work interval to the passed-in work interval
 280  * Consumes +1 ref on work_interval
 281  *
 282  * May also pass NULL to un-set work_interval on the thread
 283  *
 284  * Will deallocate any old work interval on the thread
 285  */
 286 static void
 287 thread_set_work_interval(thread_t thread,
 288                          struct work_interval *work_interval)
 289 {
 290         assert(thread == current_thread());
 291
 292         struct work_interval *old_th_wi = thread->th_work_interval;
 293
 294         /* transfer +1 ref to thread */
 295         thread->th_work_interval = work_interval;
 296
 297
 298         if (old_th_wi != NULL)
 299                 wi_release(old_th_wi);
 300 }
 301
 302 void
 303 work_interval_thread_terminate(thread_t thread)
 304 {
 305         if (thread->th_work_interval != NULL)
 306                 thread_set_work_interval(thread, NULL);
 307 }
 308
 309
 310
 311 kern_return_t
 312 kern_work_interval_notify(thread_t thread, struct kern_work_interval_args* kwi_args)
 313 {
 314         assert(thread == current_thread());
 315         assert(kwi_args->work_interval_id != 0);
 316
 317         struct work_interval *work_interval = thread->th_work_interval;
 318
 319         if (work_interval == NULL ||
 320             work_interval->wi_id != kwi_args->work_interval_id) {
 321                 /* This thread must have adopted the work interval to be able to notify */
 322                 return (KERN_INVALID_ARGUMENT);
 323         }
 324
 325         task_t notifying_task = current_task();
 326
 327         if (work_interval->wi_creator_uniqueid   != get_task_uniqueid(notifying_task) ||
 328             work_interval->wi_creator_pidversion != get_task_version(notifying_task)) {
 329                 /* Only the creating task can do a notify */
 330                 return (KERN_INVALID_ARGUMENT);
 331         }
 332
 333         spl_t s = splsched();
 334
 335
 336         uint64_t urgency_param1, urgency_param2;
 337         kwi_args->urgency = thread_get_urgency(thread, &urgency_param1, &urgency_param2);
 338
 339         splx(s);
 340
 341         /* called without interrupts disabled */
 342         machine_work_interval_notify(thread, kwi_args);
 343
 344         return (KERN_SUCCESS);
 345 }
 346
 347 /* Start at 1, 0 is not a valid work interval ID */
 348 static _Atomic uint64_t unique_work_interval_id = 1;
 349
 350 kern_return_t
 351 kern_work_interval_create(thread_t thread,
 352                           struct kern_work_interval_create_args *create_params)
 353 {
 354         assert(thread == current_thread());
 355
 356         if (thread->th_work_interval != NULL) {
 357                 /* already assigned a work interval */
 358                 return (KERN_FAILURE);
 359         }
 360
 361         struct work_interval *work_interval = kalloc(sizeof(*work_interval));
 362
 363         if (work_interval == NULL)
 364                 panic("failed to allocate work_interval");
 365
 366         bzero(work_interval, sizeof(*work_interval));
 367
 368         uint64_t old_value = atomic_fetch_add_explicit(&unique_work_interval_id, 1,
 369                                                        memory_order_relaxed);
 370
 371         uint64_t work_interval_id = old_value + 1;
 372
 373         uint32_t create_flags = create_params->wica_create_flags;
 374
 375         task_t creating_task = current_task();
 376         if ((create_flags & WORK_INTERVAL_TYPE_MASK) == WORK_INTERVAL_TYPE_CA_CLIENT) {
 377                 /*
 378                  * CA_CLIENT work intervals do not create new thread groups
 379                  * and are non-joinable.
 380                  * There can only be one CA_CLIENT work interval (created by UIKit)
 381                  * per each application task
 382                  */
 383                 if (create_flags & (WORK_INTERVAL_FLAG_JOINABLE | WORK_INTERVAL_FLAG_GROUP))
 384                         return (KERN_FAILURE);
 385                 if (!task_is_app(creating_task))
 386                         return (KERN_NOT_SUPPORTED);
 387                 if (task_set_ca_client_wi(creating_task, true) == false)
 388                         return (KERN_FAILURE);
 389         }
 390
 391         *work_interval = (struct work_interval) {
 392                 .wi_id                  = work_interval_id,
 393                 .wi_ref_count           = 1,
 394                 .wi_create_flags        = create_flags,
 395                 .wi_creator_pid         = pid_from_task(creating_task),
 396                 .wi_creator_uniqueid    = get_task_uniqueid(creating_task),
 397                 .wi_creator_pidversion  = get_task_version(creating_task),
 398         };
 399
 400
 401         if (create_flags & WORK_INTERVAL_FLAG_JOINABLE) {
 402                 /* work_interval has a +1 ref, moves to the port */
 403                 ipc_port_t port = work_interval_port_alloc(work_interval);
 404                 mach_port_name_t name = MACH_PORT_NULL;
 405
 406                 name = ipc_port_copyout_send(port, current_space());
 407
 408                 if (!MACH_PORT_VALID(name)) {
 409                         /*
 410                          * copyout failed (port is already deallocated)
 411                          * Because of the port-destroyed magic,
 412                          * the work interval is already deallocated too.
 413                          */
 414                         return KERN_RESOURCE_SHORTAGE;
 415                 }
 416
 417                 create_params->wica_port = name;
 418         } else {
 419                 /* work_interval has a +1 ref, moves to the thread */
 420                 thread_set_work_interval(thread, work_interval);
 421                 create_params->wica_port = MACH_PORT_NULL;
 422         }
 423
 424         create_params->wica_id = work_interval_id;
 425         return KERN_SUCCESS;
 426 }
 427
 428
 429 kern_return_t
 430 kern_work_interval_destroy(thread_t thread, uint64_t work_interval_id)
 431 {
 432         if (work_interval_id == 0)
 433                 return KERN_INVALID_ARGUMENT;
 434
 435         if (thread->th_work_interval == NULL ||
 436             thread->th_work_interval->wi_id != work_interval_id) {
 437                 /* work ID isn't valid or doesn't match joined work interval ID */
 438                 return (KERN_INVALID_ARGUMENT);
 439         }
 440
 441         thread_set_work_interval(thread, NULL);
 442
 443         return KERN_SUCCESS;
 444 }
 445
 446 kern_return_t
 447 kern_work_interval_join(thread_t            thread,
 448                         mach_port_name_t    port_name)
 449 {
 450         struct work_interval *work_interval = NULL;
 451         kern_return_t kr;
 452
 453         if (port_name == MACH_PORT_NULL) {
 454                 /* 'Un-join' the current work interval */
 455                 thread_set_work_interval(thread, NULL);
 456                 return KERN_SUCCESS;
 457         }
 458
 459         kr = port_name_to_work_interval(port_name, &work_interval);
 460         if (kr != KERN_SUCCESS)
 461                 return kr;
 462         /* work_interval has a +1 ref */
 463
 464         assert(work_interval != NULL);
 465
 466         thread_set_work_interval(thread, work_interval);
 467
 468         /* ref was consumed by passing it to the thread */
 469
 470         return KERN_SUCCESS;
 471 }