]> git.saurik.com Git - apple/xnu.git/blame - osfmk/ppc/chud/chud_thread.c
projects / apple / xnu.git / blame
? search:
summary | shortlog | log | commit | commitdiff | tree
blob | blame (incremental) | history | HEAD
xnu-517.12.7.tar.gz
[apple/xnu.git] / osfmk / ppc / chud / chud_thread.c
CommitLineData
55e303ae
A		 1/*
2 * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
e5568f75
A		 5 *
6 * The contents of this file constitute Original Code as defined in and
7 * are subject to the Apple Public Source License Version 1.1 (the
8 * "License"). You may not use this file except in compliance with the
9 * License. Please obtain a copy of the License at
10 * http://www.apple.com/publicsource and read it before using this file.
11 *
12 * This Original Code and all software distributed under the License are
13 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
55e303ae
A		 14 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
e5568f75
A		 16 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17 * License for the specific language governing rights and limitations
18 * under the License.
19 *
55e303ae
A		 20 * @APPLE_LICENSE_HEADER_END@
21 */
22
23#include <ppc/chud/chud_xnu.h>
24#include <kern/processor.h>
25#include <kern/thread.h>
26#include <kern/thread_act.h>
27#include <kern/ipc_tt.h>
28#include <ppc/proc_reg.h>
29#include <ppc/machine_routines.h>
30
31__private_extern__
32kern_return_t chudxnu_bind_current_thread(int cpu)
33{
34 if(cpu>=0 && cpu<chudxnu_avail_cpu_count()) { /* make sure cpu # is sane */
35 thread_bind(current_thread(), processor_ptr[cpu]);
36 thread_block((void (*)(void)) 0);
37 return KERN_SUCCESS;
38 } else {
39 return KERN_FAILURE;
40 }
41}
42
43__private_extern__
44kern_return_t chudxnu_unbind_current_thread(void)
45{
46 thread_bind(current_thread(), PROCESSOR_NULL);
47 return KERN_SUCCESS;
48}
49
50static savearea *chudxnu_private_get_regs(void)
51{
52 return current_act()->mact.pcb; // take the top savearea (user or kernel)
53}
54
55static savearea *chudxnu_private_get_user_regs(void)
56{
57 return find_user_regs(current_act()); // take the top user savearea (skip any kernel saveareas)
58}
59
60static savearea_fpu *chudxnu_private_get_fp_regs(void)
61{
62 fpu_save(current_act()->mact.curctx); // just in case it's live, save it
63 return current_act()->mact.curctx->FPUsave; // take the top savearea (user or kernel)
64}
65
66static savearea_fpu *chudxnu_private_get_user_fp_regs(void)
67{
68 return find_user_fpu(current_act()); // take the top user savearea (skip any kernel saveareas)
69}
70
71static savearea_vec *chudxnu_private_get_vec_regs(void)
72{
73 vec_save(current_act()->mact.curctx); // just in case it's live, save it
74 return current_act()->mact.curctx->VMXsave; // take the top savearea (user or kernel)
75}
76
77static savearea_vec *chudxnu_private_get_user_vec_regs(void)
78{
79 return find_user_vec(current_act()); // take the top user savearea (skip any kernel saveareas)
80}
81
82__private_extern__
83kern_return_t chudxnu_copy_savearea_to_threadstate(thread_flavor_t flavor, thread_state_t tstate, mach_msg_type_number_t *count, struct savearea *sv)
84{
85 struct ppc_thread_state *ts;
86 struct ppc_thread_state64 *xts;
87
88 switch(flavor) {
89 case PPC_THREAD_STATE:
90 if(*count < PPC_THREAD_STATE_COUNT) { /* Is the count ok? */
91 *count = 0;
92 return KERN_INVALID_ARGUMENT;
93 }
94 ts = (struct ppc_thread_state *) tstate;
95 if(sv) {
96 ts->r0 = (unsigned int)sv->save_r0;
97 ts->r1 = (unsigned int)sv->save_r1;
98 ts->r2 = (unsigned int)sv->save_r2;
99 ts->r3 = (unsigned int)sv->save_r3;
100 ts->r4 = (unsigned int)sv->save_r4;
101 ts->r5 = (unsigned int)sv->save_r5;
102 ts->r6 = (unsigned int)sv->save_r6;
103 ts->r7 = (unsigned int)sv->save_r7;
104 ts->r8 = (unsigned int)sv->save_r8;
105 ts->r9 = (unsigned int)sv->save_r9;
106 ts->r10 = (unsigned int)sv->save_r10;
107 ts->r11 = (unsigned int)sv->save_r11;
108 ts->r12 = (unsigned int)sv->save_r12;
109 ts->r13 = (unsigned int)sv->save_r13;
110 ts->r14 = (unsigned int)sv->save_r14;
111 ts->r15 = (unsigned int)sv->save_r15;
112 ts->r16 = (unsigned int)sv->save_r16;
113 ts->r17 = (unsigned int)sv->save_r17;
114 ts->r18 = (unsigned int)sv->save_r18;
115 ts->r19 = (unsigned int)sv->save_r19;
116 ts->r20 = (unsigned int)sv->save_r20;
117 ts->r21 = (unsigned int)sv->save_r21;
118 ts->r22 = (unsigned int)sv->save_r22;
119 ts->r23 = (unsigned int)sv->save_r23;
120 ts->r24 = (unsigned int)sv->save_r24;
121 ts->r25 = (unsigned int)sv->save_r25;
122 ts->r26 = (unsigned int)sv->save_r26;
123 ts->r27 = (unsigned int)sv->save_r27;
124 ts->r28 = (unsigned int)sv->save_r28;
125 ts->r29 = (unsigned int)sv->save_r29;
126 ts->r30 = (unsigned int)sv->save_r30;
127 ts->r31 = (unsigned int)sv->save_r31;
128 ts->cr = (unsigned int)sv->save_cr;
129 ts->xer = (unsigned int)sv->save_xer;
130 ts->lr = (unsigned int)sv->save_lr;
131 ts->ctr = (unsigned int)sv->save_ctr;
132 ts->srr0 = (unsigned int)sv->save_srr0;
133 ts->srr1 = (unsigned int)sv->save_srr1;
134 ts->mq = 0;
135 ts->vrsave = (unsigned int)sv->save_vrsave;
136 } else {
137 bzero((void *)ts, sizeof(struct ppc_thread_state));
138 }
139 *count = PPC_THREAD_STATE_COUNT; /* Pass back the amount we actually copied */
140 return KERN_SUCCESS;
141 break;
142 case PPC_THREAD_STATE64:
143 if(*count < PPC_THREAD_STATE64_COUNT) { /* Is the count ok? */
144 return KERN_INVALID_ARGUMENT;
145 }
146 xts = (struct ppc_thread_state64 *) tstate;
147 if(sv) {
148 xts->r0 = sv->save_r0;
149 xts->r1 = sv->save_r1;
150 xts->r2 = sv->save_r2;
151 xts->r3 = sv->save_r3;
152 xts->r4 = sv->save_r4;
153 xts->r5 = sv->save_r5;
154 xts->r6 = sv->save_r6;
155 xts->r7 = sv->save_r7;
156 xts->r8 = sv->save_r8;
157 xts->r9 = sv->save_r9;
158 xts->r10 = sv->save_r10;
159 xts->r11 = sv->save_r11;
160 xts->r12 = sv->save_r12;
161 xts->r13 = sv->save_r13;
162 xts->r14 = sv->save_r14;
163 xts->r15 = sv->save_r15;
164 xts->r16 = sv->save_r16;
165 xts->r17 = sv->save_r17;
166 xts->r18 = sv->save_r18;
167 xts->r19 = sv->save_r19;
168 xts->r20 = sv->save_r20;
169 xts->r21 = sv->save_r21;
170 xts->r22 = sv->save_r22;
171 xts->r23 = sv->save_r23;
172 xts->r24 = sv->save_r24;
173 xts->r25 = sv->save_r25;
174 xts->r26 = sv->save_r26;
175 xts->r27 = sv->save_r27;
176 xts->r28 = sv->save_r28;
177 xts->r29 = sv->save_r29;
178 xts->r30 = sv->save_r30;
179 xts->r31 = sv->save_r31;
180 xts->cr = sv->save_cr;
181 xts->xer = sv->save_xer;
182 xts->lr = sv->save_lr;
183 xts->ctr = sv->save_ctr;
184 xts->srr0 = sv->save_srr0;
185 xts->srr1 = sv->save_srr1;
186 xts->vrsave = sv->save_vrsave;
187 } else {
188 bzero((void *)xts, sizeof(struct ppc_thread_state64));
189 }
190 *count = PPC_THREAD_STATE64_COUNT; /* Pass back the amount we actually copied */
191 return KERN_SUCCESS;
192 break;
193 default:
194 *count = 0;
195 return KERN_INVALID_ARGUMENT;
196 break;
197 }
198}
199
200__private_extern__
201kern_return_t chudxnu_copy_threadstate_to_savearea(struct savearea *sv, thread_flavor_t flavor, thread_state_t tstate, mach_msg_type_number_t *count)
202{
203 struct ppc_thread_state *ts;
204 struct ppc_thread_state64 *xts;
205
206 switch(flavor) {
207 case PPC_THREAD_STATE:
208 if(*count < PPC_THREAD_STATE_COUNT) { /* Is the count ok? */
209 return KERN_INVALID_ARGUMENT;
210 }
211 ts = (struct ppc_thread_state *) tstate;
212 if(sv) {
213 sv->save_r0 = (uint64_t)ts->r0;
214 sv->save_r1 = (uint64_t)ts->r1;
215 sv->save_r2 = (uint64_t)ts->r2;
216 sv->save_r3 = (uint64_t)ts->r3;
217 sv->save_r4 = (uint64_t)ts->r4;
218 sv->save_r5 = (uint64_t)ts->r5;
219 sv->save_r6 = (uint64_t)ts->r6;
220 sv->save_r7 = (uint64_t)ts->r7;
221 sv->save_r8 = (uint64_t)ts->r8;
222 sv->save_r9 = (uint64_t)ts->r9;
223 sv->save_r10 = (uint64_t)ts->r10;
224 sv->save_r11 = (uint64_t)ts->r11;
225 sv->save_r12 = (uint64_t)ts->r12;
226 sv->save_r13 = (uint64_t)ts->r13;
227 sv->save_r14 = (uint64_t)ts->r14;
228 sv->save_r15 = (uint64_t)ts->r15;
229 sv->save_r16 = (uint64_t)ts->r16;
230 sv->save_r17 = (uint64_t)ts->r17;
231 sv->save_r18 = (uint64_t)ts->r18;
232 sv->save_r19 = (uint64_t)ts->r19;
233 sv->save_r20 = (uint64_t)ts->r20;
234 sv->save_r21 = (uint64_t)ts->r21;
235 sv->save_r22 = (uint64_t)ts->r22;
236 sv->save_r23 = (uint64_t)ts->r23;
237 sv->save_r24 = (uint64_t)ts->r24;
238 sv->save_r25 = (uint64_t)ts->r25;
239 sv->save_r26 = (uint64_t)ts->r26;
240 sv->save_r27 = (uint64_t)ts->r27;
241 sv->save_r28 = (uint64_t)ts->r28;
242 sv->save_r29 = (uint64_t)ts->r29;
243 sv->save_r30 = (uint64_t)ts->r30;
244 sv->save_r31 = (uint64_t)ts->r31;
245 sv->save_cr = ts->cr;
246 sv->save_xer = (uint64_t)ts->xer;
247 sv->save_lr = (uint64_t)ts->lr;
248 sv->save_ctr = (uint64_t)ts->ctr;
249 sv->save_srr0 = (uint64_t)ts->srr0;
250 sv->save_srr1 = (uint64_t)ts->srr1;
251 sv->save_vrsave = ts->vrsave;
252 return KERN_SUCCESS;
253 } else {
254 return KERN_FAILURE;
255 }
256 break;
257 case PPC_THREAD_STATE64:
258 if(*count < PPC_THREAD_STATE64_COUNT) { /* Is the count ok? */
259 return KERN_INVALID_ARGUMENT;
260 }
261 xts = (struct ppc_thread_state64 *) tstate;
262 if(sv) {
263 sv->save_r0 = xts->r0;
264 sv->save_r1 = xts->r1;
265 sv->save_r2 = xts->r2;
266 sv->save_r3 = xts->r3;
267 sv->save_r4 = xts->r4;
268 sv->save_r5 = xts->r5;
269 sv->save_r6 = xts->r6;
270 sv->save_r7 = xts->r7;
271 sv->save_r8 = xts->r8;
272 sv->save_r9 = xts->r9;
273 sv->save_r10 = xts->r10;
274 sv->save_r11 = xts->r11;
275 sv->save_r12 = xts->r12;
276 sv->save_r13 = xts->r13;
277 sv->save_r14 = xts->r14;
278 sv->save_r15 = xts->r15;
279 sv->save_r16 = xts->r16;
280 sv->save_r17 = xts->r17;
281 sv->save_r18 = xts->r18;
282 sv->save_r19 = xts->r19;
283 sv->save_r20 = xts->r20;
284 sv->save_r21 = xts->r21;
285 sv->save_r22 = xts->r22;
286 sv->save_r23 = xts->r23;
287 sv->save_r24 = xts->r24;
288 sv->save_r25 = xts->r25;
289 sv->save_r26 = xts->r26;
290 sv->save_r27 = xts->r27;
291 sv->save_r28 = xts->r28;
292 sv->save_r29 = xts->r29;
293 sv->save_r30 = xts->r30;
294 sv->save_r31 = xts->r31;
295 sv->save_cr = xts->cr;
296 sv->save_xer = xts->xer;
297 sv->save_lr = xts->lr;
298 sv->save_ctr = xts->ctr;
299 sv->save_srr0 = xts->srr0;
300 sv->save_srr1 = xts->srr1;
301 sv->save_vrsave = xts->vrsave;
302 return KERN_SUCCESS;
303 } else {
304 return KERN_FAILURE;
305 }
306 }
307}
308
309__private_extern__
310kern_return_t chudxnu_thread_get_state(thread_act_t thr_act,
311 thread_flavor_t flavor,
312 thread_state_t tstate,
313 mach_msg_type_number_t *count,
314 boolean_t user_only)
315{
316 if(thr_act==current_act()) {
317 if(flavor==PPC_THREAD_STATE || flavor==PPC_THREAD_STATE64) {
318 struct savearea *sv;
319 if(user_only) {
320 sv = chudxnu_private_get_user_regs();
321 } else {
322 sv = chudxnu_private_get_regs();
323 }
324 return chudxnu_copy_savearea_to_threadstate(flavor, tstate, count, sv);
325 } else if(flavor==PPC_FLOAT_STATE && user_only) {
326#warning chudxnu_thread_get_state() does not yet support supervisor FP
327 return machine_thread_get_state(current_act(), flavor, tstate, count);
328 } else if(flavor==PPC_VECTOR_STATE && user_only) {
329#warning chudxnu_thread_get_state() does not yet support supervisor VMX
330 return machine_thread_get_state(current_act(), flavor, tstate, count);
331 } else {
332 *count = 0;
333 return KERN_INVALID_ARGUMENT;
334 }
335 } else {
336 return machine_thread_get_state(thr_act, flavor, tstate, count);
337 }
338}
339
340__private_extern__
341kern_return_t chudxnu_thread_set_state(thread_act_t thr_act,
342 thread_flavor_t flavor,
343 thread_state_t tstate,
344 mach_msg_type_number_t count,
345 boolean_t user_only)
346{
347 if(thr_act==current_act()) {
348 if(flavor==PPC_THREAD_STATE || flavor==PPC_THREAD_STATE64) {
349 struct savearea *sv;
350 if(user_only) {
351 sv = chudxnu_private_get_user_regs();
352 } else {
353 sv = chudxnu_private_get_regs();
354 }
355 return chudxnu_copy_threadstate_to_savearea(sv, flavor, tstate, &count);
356 } else if(flavor==PPC_FLOAT_STATE && user_only) {
357#warning chudxnu_thread_set_state() does not yet support supervisor FP
358 return machine_thread_set_state(current_act(), flavor, tstate, count);
359 } else if(flavor==PPC_VECTOR_STATE && user_only) {
360#warning chudxnu_thread_set_state() does not yet support supervisor VMX
361 return machine_thread_set_state(current_act(), flavor, tstate, count);
362 } else {
363 return KERN_INVALID_ARGUMENT;
364 }
365 } else {
366 return machine_thread_set_state(thr_act, flavor, tstate, count);
367 }
368}
369
370static inline kern_return_t chudxnu_private_task_read_bytes(task_t task, vm_offset_t addr, int size, void *data)
371{
372
373 kern_return_t ret;
374
375 if(task==kernel_task) {
376 if(size==sizeof(unsigned int)) {
377 addr64_t phys_addr;
378 ppnum_t pp;
379
380 pp = pmap_find_phys(kernel_pmap, addr); /* Get the page number */
381 if(!pp) return KERN_FAILURE; /* Not mapped... */
382
383 phys_addr = ((addr64_t)pp << 12) | (addr & 0x0000000000000FFFULL); /* Shove in the page offset */
384
385 if(phys_addr < mem_actual) { /* Sanity check: is it in memory? */
386 *((uint32_t *)data) = ml_phys_read_64(phys_addr);
387 return KERN_SUCCESS;
388 }
389 } else {
390 return KERN_FAILURE;
391 }
392 } else {
393
394 ret = KERN_SUCCESS; /* Assume everything worked */
395 if(copyin((void *)addr, data, size)) ret = KERN_FAILURE; /* Get memory, if non-zero rc, it didn't work */
396 return ret;
397 }
398}
399
400// chudxnu_current_thread_get_callstack gathers a raw callstack along with any information needed to
401// fix it up later (in case we stopped program as it was saving values into prev stack frame, etc.)
402// after sampling has finished.
403//
404// For an N-entry callstack:
405//
406// [0] current pc
407// [1..N-3] stack frames (including current one)
408// [N-2] current LR (return value if we're in a leaf function)
409// [N-1] current r0 (in case we've saved LR in r0)
410//
411
412#define FP_LINK_OFFSET 2
413#define STACK_ALIGNMENT_MASK 0xF // PPC stack frames are supposed to be 16-byte aligned
414#define INST_ALIGNMENT_MASK 0x3 // Instructions are always 4-bytes wide
415
416#ifndef USER_MODE
417#define USER_MODE(msr) ((msr) & MASK(MSR_PR) ? TRUE : FALSE)
418#endif
419
420#ifndef SUPERVISOR_MODE
421#define SUPERVISOR_MODE(msr) ((msr) & MASK(MSR_PR) ? FALSE : TRUE)
422#endif
423
424#define VALID_STACK_ADDRESS(addr) (addr>=0x1000 && (addr&STACK_ALIGNMENT_MASK)==0x0 && (supervisor ? (addr>=kernStackMin && addr<=kernStackMax) : TRUE))
425
426__private_extern__
427kern_return_t chudxnu_current_thread_get_callstack(uint32_t *callStack,
428 mach_msg_type_number_t *count,
429 boolean_t user_only)
430{
431 kern_return_t kr;
432 vm_address_t nextFramePointer = 0;
433 vm_address_t currPC, currLR, currR0;
434 vm_address_t framePointer;
435 vm_address_t prevPC = 0;
436 vm_address_t kernStackMin = min_valid_stack_address();
437 vm_address_t kernStackMax = max_valid_stack_address();
438 unsigned int *buffer = callStack;
439 int bufferIndex = 0;
440 int bufferMaxIndex = *count;
441 boolean_t supervisor;
442 struct savearea *sv;
443
444 if(user_only) {
445 sv = chudxnu_private_get_user_regs();
446 } else {
447 sv = chudxnu_private_get_regs();
448 }
449
450 if(!sv) {
451 *count = 0;
452 return KERN_FAILURE;
453 }
454
455 supervisor = SUPERVISOR_MODE(sv->save_srr1);
456
457 if(!supervisor && ml_at_interrupt_context()) { // can't do copyin() if on interrupt stack
458 *count = 0;
459 return KERN_FAILURE;
460 }
461
462 bufferMaxIndex = bufferMaxIndex - 2; // allot space for saving the LR and R0 on the stack at the end.
463 if(bufferMaxIndex<2) {
464 *count = 0;
465 return KERN_RESOURCE_SHORTAGE;
466 }
467
468 currPC = sv->save_srr0;
469 framePointer = sv->save_r1; /* r1 is the stack pointer (no FP on PPC) */
470 currLR = sv->save_lr;
471 currR0 = sv->save_r0;
472
473 bufferIndex = 0; // start with a stack of size zero
474 buffer[bufferIndex++] = currPC; // save PC in position 0.
475
476 // Now, fill buffer with stack backtraces.
477 while(bufferIndex<bufferMaxIndex && VALID_STACK_ADDRESS(framePointer)) {
478 vm_address_t pc = 0;
479 // Above the stack pointer, the following values are saved:
480 // saved LR
481 // saved CR
482 // saved SP
483 //-> SP
484 // Here, we'll get the lr from the stack.
485 volatile vm_address_t fp_link = (vm_address_t)(((unsigned *)framePointer)+FP_LINK_OFFSET);
486
487 // Note that we read the pc even for the first stack frame (which, in theory,
488 // is always empty because the callee fills it in just before it lowers the
489 // stack. However, if we catch the program in between filling in the return
490 // address and lowering the stack, we want to still have a valid backtrace.
491 // FixupStack correctly disregards this value if necessary.
492
493 if(supervisor) {
494 kr = chudxnu_private_task_read_bytes(kernel_task, fp_link, sizeof(unsigned int), &pc);
495 } else {
496 kr = chudxnu_private_task_read_bytes(current_task(), fp_link, sizeof(unsigned int), &pc);
497 }
498 if(kr!=KERN_SUCCESS) {
499 // IOLog("task_read_callstack: unable to read framePointer: %08x\n",framePointer);
500 pc = 0;
501 break;
502 }
503
504 // retrieve the contents of the frame pointer and advance to the next stack frame if it's valid
505
506 if(supervisor) {
507 kr = chudxnu_private_task_read_bytes(kernel_task, framePointer, sizeof(unsigned int), &nextFramePointer);
508 } else {
509 kr = chudxnu_private_task_read_bytes(current_task(), framePointer, sizeof(unsigned int), &nextFramePointer);
510 }
511 if(kr!=KERN_SUCCESS) {
512 nextFramePointer = 0;
513 }
514
515 if(nextFramePointer) {
516 buffer[bufferIndex++] = pc;
517 prevPC = pc;
518 }
519
520 if(nextFramePointer<framePointer) {
521 break;
522 } else {
523 framePointer = nextFramePointer;
524 }
525 }
526
527 if(bufferIndex>=bufferMaxIndex) {
528 *count = 0;
529 return KERN_RESOURCE_SHORTAGE;
530 }
531
532 // Save link register and R0 at bottom of stack. This means that we won't worry
533 // about these values messing up stack compression. These end up being used
534 // by FixupStack.
535 buffer[bufferIndex++] = currLR;
536 buffer[bufferIndex++] = currR0;
537
538 *count = bufferIndex;
539 return KERN_SUCCESS;
540}
541
542__private_extern__
543int chudxnu_task_threads(task_t task,
544 thread_act_array_t *thr_act_list,
545 mach_msg_type_number_t *count)
546{
547 mach_msg_type_number_t task_thread_count = 0;
548 kern_return_t kr;
549
550 kr = task_threads(current_task(), thr_act_list, count);
551 if(kr==KERN_SUCCESS) {
552 thread_act_t thr_act;
553 int i, state_count;
554 for(i=0; i<(*count); i++) {
555 thr_act = convert_port_to_act(((ipc_port_t *)(*thr_act_list))[i]);
556 /* undo the mig conversion task_threads does */
557 thr_act_list[i] = thr_act;
558 }
559 }
560 return kr;
561}
562
563__private_extern__
564thread_act_t chudxnu_current_act(void)
565{
566 return current_act();
567}
568
569__private_extern__
570task_t chudxnu_current_task(void)
571{
572 return current_task();
573}
574
575__private_extern__
576kern_return_t chudxnu_thread_info(thread_act_t thr_act,
577 thread_flavor_t flavor,
578 thread_info_t thread_info_out,
579 mach_msg_type_number_t *thread_info_count)
580{
581 return thread_info(thr_act, flavor, thread_info_out, thread_info_count);
582}
mirror of XNU