1 /*
2 * Copyright (c) 2000-2016 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 #include <mach/mach_types.h>
30 #include <mach/exception_types.h>
31 #include <arm/exception.h>
32 #include <arm/pmap.h>
33 #include <arm64/proc_reg.h>
34 #include <arm/thread.h>
35 #include <arm/trap_internal.h>
36 #include <arm/cpu_data_internal.h>
37 #include <kdp/kdp_internal.h>
38 #include <kern/debug.h>
39 #include <IOKit/IOPlatformExpert.h>
40 #include <libkern/OSAtomic.h>
41 #include <vm/vm_map.h>
42 #include <arm/misc_protos.h>
43
44 #if defined(HAS_APPLE_PAC)
45 #include <ptrauth.h>
46 #endif
47
48 #define KDP_TEST_HARNESS 0
49 #if KDP_TEST_HARNESS
50 #define dprintf(x) kprintf x
51 #else
52 #define dprintf(x) do {} while (0)
53 #endif
54
55 void halt_all_cpus(boolean_t);
56 void kdp_call(void);
57 int kdp_getc(void);
58 int machine_trace_thread(thread_t thread,
59 char * tracepos,
60 char * tracebound,
61 int nframes,
62 uint32_t * thread_trace_flags);
63 int machine_trace_thread64(thread_t thread,
64 char * tracepos,
65 char * tracebound,
66 int nframes,
67 uint32_t * thread_trace_flags);
68
69 void kdp_trap(unsigned int, struct arm_saved_state * saved_state);
70
71 extern bool machine_trace_thread_validate_kva(vm_offset_t addr);
72
73 #if CONFIG_KDP_INTERACTIVE_DEBUGGING
74 void
kdp_exception(unsigned char * pkt,int * len,unsigned short * remote_port,unsigned int exception,unsigned int code,unsigned int subcode)75 kdp_exception(
76 unsigned char * pkt, int * len, unsigned short * remote_port, unsigned int exception, unsigned int code, unsigned int subcode)
77 {
78 struct {
79 kdp_exception_t pkt;
80 kdp_exc_info_t exc;
81 } aligned_pkt;
82
83 kdp_exception_t * rq = (kdp_exception_t *)&aligned_pkt;
84
85 bcopy((char *)pkt, (char *)rq, sizeof(*rq));
86 rq->hdr.request = KDP_EXCEPTION;
87 rq->hdr.is_reply = 0;
88 rq->hdr.seq = kdp.exception_seq;
89 rq->hdr.key = 0;
90 rq->hdr.len = sizeof(*rq) + sizeof(kdp_exc_info_t);
91
92 rq->n_exc_info = 1;
93 rq->exc_info[0].cpu = 0;
94 rq->exc_info[0].exception = exception;
95 rq->exc_info[0].code = code;
96 rq->exc_info[0].subcode = subcode;
97
98 rq->hdr.len += rq->n_exc_info * sizeof(kdp_exc_info_t);
99
100 bcopy((char *)rq, (char *)pkt, rq->hdr.len);
101
102 kdp.exception_ack_needed = TRUE;
103
104 *remote_port = kdp.exception_port;
105 *len = rq->hdr.len;
106 }
107
108 boolean_t
kdp_exception_ack(unsigned char * pkt,int len)109 kdp_exception_ack(unsigned char * pkt, int len)
110 {
111 kdp_exception_ack_t aligned_pkt;
112 kdp_exception_ack_t * rq = (kdp_exception_ack_t *)&aligned_pkt;
113
114 if ((unsigned)len < sizeof(*rq)) {
115 return FALSE;
116 }
117
118 bcopy((char *)pkt, (char *)rq, sizeof(*rq));
119
120 if (!rq->hdr.is_reply || rq->hdr.request != KDP_EXCEPTION) {
121 return FALSE;
122 }
123
124 dprintf(("kdp_exception_ack seq %x %x\n", rq->hdr.seq, kdp.exception_seq));
125
126 if (rq->hdr.seq == kdp.exception_seq) {
127 kdp.exception_ack_needed = FALSE;
128 kdp.exception_seq++;
129 }
130 return TRUE;
131 }
132
133 static void
kdp_getintegerstate(char * out_state)134 kdp_getintegerstate(char * out_state)
135 {
136 #if defined(__arm64__)
137 struct arm_thread_state64 thread_state64;
138 arm_saved_state_t *saved_state;
139
140 saved_state = kdp.saved_state;
141 assert(is_saved_state64(saved_state));
142
143 bzero((char *) &thread_state64, sizeof(struct arm_thread_state64));
144
145 saved_state_to_thread_state64(saved_state, &thread_state64);
146
147 bcopy((char *) &thread_state64, (char *) out_state, sizeof(struct arm_thread_state64));
148 #else
149 #error Unknown architecture.
150 #endif
151 }
152
153 kdp_error_t
kdp_machine_read_regs(__unused unsigned int cpu,unsigned int flavor,char * data,int * size)154 kdp_machine_read_regs(__unused unsigned int cpu, unsigned int flavor, char * data, int * size)
155 {
156 switch (flavor) {
157 #if defined(__arm64__)
158 case ARM_THREAD_STATE64:
159 dprintf(("kdp_readregs THREAD_STATE64\n"));
160 kdp_getintegerstate(data);
161 *size = ARM_THREAD_STATE64_COUNT * sizeof(int);
162 return KDPERR_NO_ERROR;
163 #endif
164
165 case ARM_VFP_STATE:
166 dprintf(("kdp_readregs THREAD_FPSTATE\n"));
167 bzero((char *) data, sizeof(struct arm_vfp_state));
168 *size = ARM_VFP_STATE_COUNT * sizeof(int);
169 return KDPERR_NO_ERROR;
170
171 default:
172 dprintf(("kdp_readregs bad flavor %d\n"));
173 return KDPERR_BADFLAVOR;
174 }
175 }
176
177 static void
kdp_setintegerstate(char * state_in)178 kdp_setintegerstate(char * state_in)
179 {
180 #if defined(__arm64__)
181 struct arm_thread_state64 thread_state64;
182 struct arm_saved_state *saved_state;
183
184 bcopy((char *) state_in, (char *) &thread_state64, sizeof(struct arm_thread_state64));
185 saved_state = kdp.saved_state;
186 assert(is_saved_state64(saved_state));
187
188 /*
189 * thread_state64_to_saved_state() expects the target thread to be EL0
190 * state and ignores attempts to change many CPSR bits.
191 * kdp_setintegerstate() is rarely used and is gated behind significant
192 * security boundaries. So rather than creating a variant of
193 * thread_state64_to_saved_state() just for kdp_setintegerstate(), it's
194 * simpler to reset CPSR.M before converting, then adjust CPSR after
195 * conversion.
196 */
197 uint32_t cpsr = get_saved_state_cpsr(saved_state);
198 cpsr &= ~(PSR64_MODE_EL_MASK);
199 cpsr |= PSR64_MODE_EL0;
200 set_saved_state_cpsr(saved_state, cpsr);
201 thread_state64_to_saved_state(&thread_state64, saved_state);
202 set_saved_state_cpsr(saved_state, thread_state64.cpsr);
203 #else
204 #error Unknown architecture.
205 #endif
206 }
207
208 kdp_error_t
kdp_machine_write_regs(__unused unsigned int cpu,unsigned int flavor,char * data,__unused int * size)209 kdp_machine_write_regs(__unused unsigned int cpu, unsigned int flavor, char * data, __unused int * size)
210 {
211 switch (flavor) {
212 #if defined(__arm64__)
213 case ARM_THREAD_STATE64:
214 dprintf(("kdp_writeregs THREAD_STATE64\n"));
215 kdp_setintegerstate(data);
216 return KDPERR_NO_ERROR;
217 #endif
218
219 case ARM_VFP_STATE:
220 dprintf(("kdp_writeregs THREAD_FPSTATE\n"));
221 return KDPERR_NO_ERROR;
222
223 default:
224 dprintf(("kdp_writeregs bad flavor %d\n"));
225 return KDPERR_BADFLAVOR;
226 }
227 }
228
229 void
kdp_machine_hostinfo(kdp_hostinfo_t * hostinfo)230 kdp_machine_hostinfo(kdp_hostinfo_t * hostinfo)
231 {
232 hostinfo->cpus_mask = 1;
233 hostinfo->cpu_type = slot_type(0);
234 hostinfo->cpu_subtype = slot_subtype(0);
235 }
236
237 __attribute__((noreturn))
238 void
kdp_panic(const char * fmt,...)239 kdp_panic(const char * fmt, ...)
240 {
241 #pragma clang diagnostic push
242 #pragma clang diagnostic ignored "-Wformat-nonliteral"
243 char kdp_fmt[256];
244 va_list args;
245
246 va_start(args, fmt);
247 (void) snprintf(kdp_fmt, sizeof(kdp_fmt), "kdp panic: %s", fmt);
248 vprintf(kdp_fmt, args);
249 va_end(args);
250
251 while (1) {
252 }
253 ;
254 #pragma clang diagnostic pop
255 }
256
257 int
kdp_intr_disbl(void)258 kdp_intr_disbl(void)
259 {
260 return splhigh();
261 }
262
263 void
kdp_intr_enbl(int s)264 kdp_intr_enbl(int s)
265 {
266 splx(s);
267 }
268
269 void
kdp_us_spin(int usec)270 kdp_us_spin(int usec)
271 {
272 delay(usec / 100);
273 }
274
275 void
kdp_call(void)276 kdp_call(void)
277 {
278 Debugger("inline call to debugger(machine_startup)");
279 }
280
281 int
kdp_getc(void)282 kdp_getc(void)
283 {
284 return console_try_read_char();
285 }
286
287 void
kdp_machine_get_breakinsn(uint8_t * bytes,uint32_t * size)288 kdp_machine_get_breakinsn(uint8_t * bytes, uint32_t * size)
289 {
290 *(uint32_t *)bytes = GDB_TRAP_INSTR1;
291 *size = sizeof(uint32_t);
292 }
293
294 void
kdp_sync_cache(void)295 kdp_sync_cache(void)
296 {
297 }
298
299 int
kdp_machine_ioport_read(kdp_readioport_req_t * rq,caddr_t data,uint16_t lcpu)300 kdp_machine_ioport_read(kdp_readioport_req_t * rq, caddr_t data, uint16_t lcpu)
301 {
302 #pragma unused(rq, data, lcpu)
303 return 0;
304 }
305
306 int
kdp_machine_ioport_write(kdp_writeioport_req_t * rq,caddr_t data,uint16_t lcpu)307 kdp_machine_ioport_write(kdp_writeioport_req_t * rq, caddr_t data, uint16_t lcpu)
308 {
309 #pragma unused(rq, data, lcpu)
310 return 0;
311 }
312
313 int
kdp_machine_msr64_read(kdp_readmsr64_req_t * rq,caddr_t data,uint16_t lcpu)314 kdp_machine_msr64_read(kdp_readmsr64_req_t *rq, caddr_t data, uint16_t lcpu)
315 {
316 #pragma unused(rq, data, lcpu)
317 return 0;
318 }
319
320 int
kdp_machine_msr64_write(kdp_writemsr64_req_t * rq,caddr_t data,uint16_t lcpu)321 kdp_machine_msr64_write(kdp_writemsr64_req_t *rq, caddr_t data, uint16_t lcpu)
322 {
323 #pragma unused(rq, data, lcpu)
324 return 0;
325 }
326 #endif /* CONFIG_KDP_INTERACTIVE_DEBUGGING */
327
328 void
kdp_trap(unsigned int exception,struct arm_saved_state * saved_state)329 kdp_trap(unsigned int exception, struct arm_saved_state * saved_state)
330 {
331 handle_debugger_trap(exception, 0, 0, saved_state);
332
333 #if defined(__arm64__)
334 assert(is_saved_state64(saved_state));
335
336 #if HAS_APPLE_PAC
337 MANIPULATE_SIGNED_THREAD_STATE(saved_state,
338 "ldr w6, [x1] \n"
339 "mov w7, %[GDB_TRAP_INSTR1_L] \n"
340 "movk w7, %[GDB_TRAP_INSTR1_H], lsl #16 \n"
341 "cmp w6, w7 \n"
342 "b.eq 1f \n"
343 "mov w7, %[GDB_TRAP_INSTR2_L] \n"
344 "movk w7, %[GDB_TRAP_INSTR2_H], lsl #16 \n"
345 "cmp w6, w7 \n"
346 "b.ne 0f \n"
347 "1: \n"
348 "add x1, x1, #4 \n"
349 "str x1, [x0, %[SS64_PC]] \n",
350 [GDB_TRAP_INSTR1_L] "i" (GDB_TRAP_INSTR1 & 0xFFFF),
351 [GDB_TRAP_INSTR1_H] "i" (GDB_TRAP_INSTR1 >> 16),
352 [GDB_TRAP_INSTR2_L] "i" (GDB_TRAP_INSTR2 & 0xFFFF),
353 [GDB_TRAP_INSTR2_H] "i" (GDB_TRAP_INSTR2 >> 16)
354 );
355 #else
356 uint32_t instr = *((uint32_t *)get_saved_state_pc(saved_state));
357
358 /*
359 * As long as we are using the arm32 trap encoding to handling
360 * traps to the debugger, we should identify both variants and
361 * increment for both of them.
362 */
363 if ((instr == GDB_TRAP_INSTR1) || (instr == GDB_TRAP_INSTR2)) {
364 saved_state64(saved_state)->pc += 4;
365 }
366 #endif
367
368 #else
369 #error Unknown architecture.
370 #endif
371 }
372
373 #define ARM32_LR_OFFSET 4
374 #define ARM64_LR_OFFSET 8
375
376 /*
377 * Since sizeof (struct thread_snapshot) % 4 == 2
378 * make sure the compiler does not try to use word-aligned
379 * access to this data, which can result in alignment faults
380 * that can't be emulated in KDP context.
381 */
382 typedef uint32_t uint32_align2_t __attribute__((aligned(2)));
383
384 /*
385 * @function _was_in_userspace
386 *
387 * @abstract Unused function used to indicate that a CPU was in userspace
388 * before it was IPI'd to enter the Debugger context.
389 *
390 * @discussion This function should never actually be called.
391 */
392 void __attribute__((__noreturn__))
_was_in_userspace(void)393 _was_in_userspace(void)
394 {
395 panic("%s: should not have been invoked.", __FUNCTION__);
396 }
397
398 int
machine_trace_thread64(thread_t thread,char * tracepos,char * tracebound,int nframes,uint32_t * thread_trace_flags)399 machine_trace_thread64(thread_t thread,
400 char * tracepos,
401 char * tracebound,
402 int nframes,
403 uint32_t * thread_trace_flags)
404 {
405 #if defined(__arm64__)
406
407 uint64_t * tracebuf = (uint64_t *)tracepos;
408 vm_size_t framesize = sizeof(uint64_t);
409
410 vm_offset_t stacklimit = 0;
411 vm_offset_t stacklimit_bottom = 0;
412 int framecount = 0;
413 vm_offset_t pc = 0;
414 vm_offset_t fp = 0;
415 vm_offset_t sp = 0;
416 vm_offset_t prevfp = 0;
417 uint64_t prevlr = 0;
418 vm_offset_t kern_virt_addr = 0;
419
420 nframes = (tracebound > tracepos) ? MIN(nframes, (int)((tracebound - tracepos) / framesize)) : 0;
421 if (!nframes) {
422 return 0;
423 }
424 framecount = 0;
425
426 struct arm_saved_state *state = thread->machine.kpcb;
427 if (state != NULL) {
428 fp = state->ss_64.fp;
429
430 prevlr = state->ss_64.lr;
431 pc = state->ss_64.pc;
432 sp = state->ss_64.sp;
433 } else {
434 /* kstackptr may not always be there, so recompute it */
435 arm_kernel_saved_state_t *kstate = &thread_get_kernel_state(thread)->machine.ss;
436
437 fp = kstate->fp;
438 prevlr = kstate->lr;
439 pc = kstate->pc_was_in_userspace ? (register_t)ptrauth_strip((void *)&_was_in_userspace, ptrauth_key_function_pointer) : 0;
440 sp = kstate->sp;
441 }
442
443 stacklimit = VM_MAX_KERNEL_ADDRESS;
444 stacklimit_bottom = VM_MIN_KERNEL_ADDRESS;
445
446 if (!prevlr && !fp && !sp && !pc) {
447 return 0;
448 }
449
450 prevlr = VM_KERNEL_UNSLIDE(prevlr);
451
452 for (; framecount < nframes; framecount++) {
453 *tracebuf++ = prevlr;
454
455 /* Invalid frame */
456 if (!fp) {
457 break;
458 }
459 /*
460 * Unaligned frame; given that the stack register must always be
461 * 16-byte aligned, we are assured 8-byte alignment of the saved
462 * frame pointer and link register.
463 */
464 if (fp & 0x0000007) {
465 break;
466 }
467 /* Frame is out of range, maybe a user FP while doing kernel BT */
468 if (fp > stacklimit) {
469 break;
470 }
471 if (fp < stacklimit_bottom) {
472 break;
473 }
474 /* Stack grows downward */
475 if (fp < prevfp) {
476 bool switched_stacks = false;
477
478 /*
479 * As a special case, sometimes we are backtracing out of an interrupt
480 * handler, and the stack jumps downward because of the memory allocation
481 * pattern during early boot due to KASLR.
482 */
483 int cpu;
484 int max_cpu = ml_get_max_cpu_number();
485
486 for (cpu = 0; cpu <= max_cpu; cpu++) {
487 cpu_data_t *target_cpu_datap;
488
489 target_cpu_datap = (cpu_data_t *)CpuDataEntries[cpu].cpu_data_vaddr;
490 if (target_cpu_datap == (cpu_data_t *)NULL) {
491 continue;
492 }
493
494 if (prevfp >= (target_cpu_datap->intstack_top - INTSTACK_SIZE) && prevfp < target_cpu_datap->intstack_top) {
495 switched_stacks = true;
496 break;
497 }
498 #if defined(__arm64__)
499 if (prevfp >= (target_cpu_datap->excepstack_top - EXCEPSTACK_SIZE) && prevfp < target_cpu_datap->excepstack_top) {
500 switched_stacks = true;
501 break;
502 }
503 #endif
504 }
505
506 /**
507 * The stack could be "growing upwards" because this frame is
508 * stitching two different stacks together. There can be more than
509 * one non-XNU stack so if both frames are in non-XNU stacks but it
510 * looks like the stack is growing upward, then assume that we've
511 * switched from one non-XNU stack to another.
512 */
513 if ((ml_addr_in_non_xnu_stack(prevfp) != ml_addr_in_non_xnu_stack(fp)) ||
514 (ml_addr_in_non_xnu_stack(prevfp) && ml_addr_in_non_xnu_stack(fp))) {
515 switched_stacks = true;
516 }
517
518 if (!switched_stacks) {
519 /* Corrupt frame pointer? */
520 break;
521 }
522 }
523
524 /* Assume there's a saved link register, and read it */
525 kern_virt_addr = fp + ARM64_LR_OFFSET;
526 bool ok = machine_trace_thread_validate_kva(kern_virt_addr);
527 if (!ok) {
528 if (thread_trace_flags != NULL) {
529 *thread_trace_flags |= kThreadTruncatedBT;
530 }
531
532 break;
533 }
534
535 prevlr = *(uint64_t *)kern_virt_addr;
536 #if defined(HAS_APPLE_PAC)
537 /* return addresses on stack signed by arm64e ABI */
538 prevlr = (uint64_t) ptrauth_strip((void *)prevlr, ptrauth_key_return_address);
539 #endif
540 prevlr = VM_KERNEL_UNSLIDE(prevlr);
541
542 prevfp = fp;
543 /* Next frame */
544 kern_virt_addr = fp;
545 ok = machine_trace_thread_validate_kva(kern_virt_addr);
546 if (!ok) {
547 if (thread_trace_flags != NULL) {
548 *thread_trace_flags |= kThreadTruncatedBT;
549 }
550 fp = 0;
551 break;
552 }
553
554 fp = *(uint64_t *)kern_virt_addr;
555 #if defined(HAS_APPLE_PAC)
556 /* frame pointers on stack signed by arm64e ABI */
557 fp = (uint64_t) ptrauth_strip((void *)fp, ptrauth_key_frame_pointer);
558 #endif
559 }
560 return (int)(((char *)tracebuf) - tracepos);
561 #else
562 #error Unknown architecture.
563 #endif
564 }
565
566 void
kdp_ml_enter_debugger(void)567 kdp_ml_enter_debugger(void)
568 {
569 __asm__ volatile (".long 0xe7ffdefe");
570 }
571