1 /*
2 * Copyright (c) 2007-2023 Apple Inc. All rights reserved.
3 * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
4 */
5
6
7 /* Required to know if we must compile the file. */
8 #include <pexpert/arm64/board_config.h>
9
10 /* Generic headers. */
11 #include <pexpert/pexpert.h>
12 #include <pexpert/device_tree.h>
13 #include <machine/machine_routines.h>
14 #include <sys/sysctl.h>
15 #include <kern/clock.h>
16
17 /* Dev headers. */
18 #if DEVELOPMENT || DEBUG
19 #include <kern/simple_lock.h>
20 #include <os/hash.h>
21 #endif /* DEVELOPMENT || DEBUG */
22
23 /* Trace-specific headers. */
24
25 /********
26 * Logs *
27 ********/
28
29 #define PANIC_TRACE_LOG 1
30 #define panic_trace_error(msg, args...) { if (panic_trace_debug == 1) kprintf("panic_trace: " msg "\n", ##args); else if (panic_trace_debug == 2) printf("panic_trace: " msg "\n", ##args); }
31 #if PANIC_TRACE_LOG
32 #define panic_trace_log(msg, args...) { if (panic_trace_debug) panic_trace_error(msg, ##args); }
33 #else
34 #define panic_trace_log(msg, args...)
35 #endif /* PANIC_TRACE_LOG */
36
37 /************
38 * Externals *
39 ************/
40
41 /*
42 * Soc base physical address.
43 * Set by pe_identify_machine.c:pe_arm_map_interrupt_controller during
44 * early boot, null before.
45 */
46 extern vm_offset_t gSocPhys;
47
48 /*******
49 * Logs *
50 *******/
51
52 #if DEVELOPMENT || DEBUG
53 #ifndef CT_DFT_LOGS_ON
54 #define CT_DFT_LOGS_ON 0
55 #endif /* CT_DFT_LOGS_ON */
56 #endif /* DEVELOPMENT || DEBUG */
57
58 /****************
59 * Default state *
60 ****************/
61
62 #if DEVELOPMENT || DEBUG
63
64 /*
65 * When supported, panic-trace is enabled by default on some platforms.
66 * This section defines on which platform it is enabled..
67 */
68
69 /* Opensource -> disabled. */
70 #define DEFAULT_PANIC_TRACE_MODE panic_trace_disabled
71
72 #endif /* DEVELOPMENT || DEBUG */
73
74 /**********
75 * Globals *
76 **********/
77
78 #if DEVELOPMENT || DEBUG
79 boolean_t panic_trace_disabled_for_rdar107003520 = FALSE;
80 #endif /* DEVELOPMENT || DEBUG */
81
82 static boolean_t debug_and_trace_initialized = false;
83
84 /************
85 * Boot-args *
86 ************/
87
88 #if DEVELOPMENT || DEBUG
89 /*
90 * Panic trace state.
91 * Has a double meaning :
92 * - at system init, it gives the expected tracing state.
93 * -> init code uses that to enable tracing.
94 * - after system init, used to report the tracing state.
95 */
96 TUNABLE_DT_WRITEABLE(panic_trace_t, panic_trace, "/arm-io/cpu-debug-interface",
97 "panic-trace-mode", "panic_trace", DEFAULT_PANIC_TRACE_MODE, TUNABLE_DT_NONE);
98
99 /*
100 * Panic trace debug state. See 'Logs' section above.
101 */
102 TUNABLE_WRITEABLE(boolean_t, panic_trace_debug, "panic_trace_debug", CT_DFT_LOGS_ON);
103
104 #endif /* DEVELOPMENT || DEBUG */
105
106 /********
107 * Locks *
108 ********/
109
110 /* Panic trace lock. */
111
112 /****************
113 * Debug command *
114 ****************/
115
116 #if DEVELOPMENT || DEBUG
117
118 decl_simple_lock_data(, panic_hook_lock);
119
120 TUNABLE(unsigned int, bootarg_stop_clocks, "stop_clocks", 0);
121
122 // The command buffer contains the converted commands from the device tree for commanding cpu_halt, enable_trace, etc.
123 #define DEBUG_COMMAND_BUFFER_SIZE 256
124 typedef struct command_buffer_element {
125 uintptr_t address;
126 uintptr_t address_pa;
127 uintptr_t value;
128 union cpu_selector {
129 uint16_t mask;
130 struct cpu_range {
131 uint8_t min_cpu;
132 uint8_t max_cpu;
133 } range;
134 } destination_cpu_selector;
135 uint16_t delay_us;
136 bool cpu_selector_is_range;
137 bool is_32bit;
138 } command_buffer_element_t;
139
140 #define CPU_SELECTOR_SHIFT (16)
141 #define CPU_SELECTOR_MASK (0xFFFF << CPU_SELECTOR_SHIFT)
142 #define REGISTER_OFFSET_MASK ((1 << CPU_SELECTOR_SHIFT) - 1)
143 #define REGISTER_OFFSET(register_prop) (register_prop & REGISTER_OFFSET_MASK)
144 #define CPU_SELECTOR(register_offset) ((register_offset & CPU_SELECTOR_MASK) >> CPU_SELECTOR_SHIFT) // Upper 16bits holds the cpu selector
145 #define MAX_WINDOW_SIZE 0xFFFF
146 #define DELAY_SHIFT (32)
147 #define DELAY_MASK (0xFFFFULL << DELAY_SHIFT)
148 #define DELAY_US(register_offset) ((register_offset & DELAY_MASK) >> DELAY_SHIFT)
149 #define CPU_SELECTOR_ISRANGE_MASK (1ULL << 62)
150 #define REGISTER_32BIT_MASK (1ULL << 63)
151 #define ALL_CPUS 0x0000
152 #define RESET_VIRTUAL_ADDRESS_WINDOW 0xFFFFFFFF
153
154 #define REGISTER_IS_32BIT(register_offset) ((register_offset & REGISTER_32BIT_MASK) != 0)
155 #define REGISTER_SIZE(register_offset) (REGISTER_IS_32BIT(register_offset) ? sizeof(uint32_t) : sizeof(uintptr_t))
156 #define CPU_SELECTOR_IS_RANGE(register_offset) ((register_offset & CPU_SELECTOR_ISRANGE_MASK) != 0)
157 #define CPU_SELECTOR_MIN_CPU(register_offset) ((CPU_SELECTOR(register_offset) & 0xff00) >> 8)
158 #define CPU_SELECTOR_MAX_CPU(register_offset) (CPU_SELECTOR(register_offset) & 0x00ff)
159
160 // Record which CPU is currently running one of our debug commands, so we can trap panic reentrancy to PE_arm_debug_panic_hook.
161 static int running_debug_command_on_cpu_number = -1;
162
163
164 // Determine whether the current debug command is intended for this CPU.
165 static inline bool
is_running_cpu_selected(command_buffer_element_t * command)166 is_running_cpu_selected(command_buffer_element_t *command)
167 {
168 assert(running_debug_command_on_cpu_number >= 0);
169 if (command->cpu_selector_is_range) {
170 return running_debug_command_on_cpu_number >= command->destination_cpu_selector.range.min_cpu
171 && running_debug_command_on_cpu_number <= command->destination_cpu_selector.range.max_cpu;
172 } else if (command->destination_cpu_selector.mask == ALL_CPUS) {
173 return true;
174 } else {
175 return !!(command->destination_cpu_selector.mask & (1 << running_debug_command_on_cpu_number));
176 }
177 }
178
179
180 // Pointers into debug_command_buffer for each operation. Assumes runtime will init them to zero.
181 static command_buffer_element_t *cpu_halt;
182 static command_buffer_element_t *enable_trace;
183 static command_buffer_element_t *enable_alt_trace;
184 static command_buffer_element_t *trace_halt;
185 static command_buffer_element_t *enable_stop_clocks;
186 static command_buffer_element_t *stop_clocks;
187
188 boolean_t
PE_arm_debug_and_trace_initialized(void)189 PE_arm_debug_and_trace_initialized(void)
190 {
191 return debug_and_trace_initialized;
192 }
193
194 static void
pe_init_debug_command(DTEntry entryP,command_buffer_element_t ** command_buffer,const char * entry_name)195 pe_init_debug_command(DTEntry entryP, command_buffer_element_t **command_buffer, const char* entry_name)
196 {
197 // statically allocate to prevent needing alloc at runtime
198 static command_buffer_element_t debug_command_buffer[DEBUG_COMMAND_BUFFER_SIZE];
199 static command_buffer_element_t *next_command_buffer_entry = debug_command_buffer;
200
201 // record this pointer but don't assign it to *command_buffer yet, in case we panic while half-initialized
202 command_buffer_element_t *command_starting_index = next_command_buffer_entry;
203
204 uintptr_t const *reg_prop;
205 uint32_t prop_size, reg_window_size = 0;
206 uintptr_t base_address_pa = 0, debug_reg_window = 0;
207
208 if (command_buffer == 0) {
209 panic_trace_log("%s: %s: no hook to assign this command to\n", __func__, entry_name);
210 return;
211 }
212
213 if (SecureDTGetProperty(entryP, entry_name, (void const **)®_prop, &prop_size) != kSuccess) {
214 panic("%s: %s: failed to read property from device tree", __func__, entry_name);
215 }
216
217 if (prop_size % (2 * sizeof(*reg_prop))) {
218 panic("%s: %s: property size %u bytes is not a multiple of %lu",
219 __func__, entry_name, prop_size, 2 * sizeof(*reg_prop));
220 }
221
222 // convert to real virt addresses and stuff commands into debug_command_buffer
223 for (; prop_size; reg_prop += 2, prop_size -= 2 * sizeof(*reg_prop)) {
224 if (*reg_prop == RESET_VIRTUAL_ADDRESS_WINDOW) {
225 debug_reg_window = 0; // Create a new window
226 } else if (debug_reg_window == 0) {
227 // create a window from virtual address to the specified physical address
228 base_address_pa = gSocPhys + *reg_prop;
229 reg_window_size = ((uint32_t)*(reg_prop + 1));
230 if (reg_window_size > MAX_WINDOW_SIZE) {
231 panic("%s: %s: %#x-byte window at #%lx exceeds maximum size of %#x",
232 __func__, entry_name, reg_window_size, base_address_pa, MAX_WINDOW_SIZE );
233 }
234 debug_reg_window = ml_io_map(base_address_pa, reg_window_size);
235 assert(debug_reg_window);
236 panic_trace_log("%s: %s: %#x bytes at %#lx mapped to %#lx\n",
237 __func__, entry_name, reg_window_size, base_address_pa, debug_reg_window );
238 } else {
239 if ((REGISTER_OFFSET(*reg_prop) + REGISTER_SIZE(*reg_prop)) > reg_window_size) {
240 panic("%s: %s[%ld]: %#lx(+%lu)-byte offset from %#lx exceeds allocated size of %#x",
241 __func__, entry_name, next_command_buffer_entry - command_starting_index,
242 REGISTER_OFFSET(*reg_prop), REGISTER_SIZE(*reg_prop), base_address_pa, reg_window_size );
243 }
244
245 if (next_command_buffer_entry - debug_command_buffer >= DEBUG_COMMAND_BUFFER_SIZE - 1) {
246 // can't use the very last entry, since we need it to terminate the command
247 panic("%s: %s[%ld]: out of space in command buffer",
248 __func__, entry_name, next_command_buffer_entry - command_starting_index );
249 }
250
251 next_command_buffer_entry->address = debug_reg_window + REGISTER_OFFSET(*reg_prop);
252 next_command_buffer_entry->address_pa = base_address_pa + REGISTER_OFFSET(*reg_prop);
253 next_command_buffer_entry->value = *(reg_prop + 1);
254 #if defined(__arm64__)
255 next_command_buffer_entry->delay_us = DELAY_US(*reg_prop);
256 next_command_buffer_entry->is_32bit = REGISTER_IS_32BIT(*reg_prop);
257 #else
258 next_command_buffer_entry->delay_us = 0;
259 next_command_buffer_entry->is_32bit = false;
260 #endif
261 if ((next_command_buffer_entry->cpu_selector_is_range = CPU_SELECTOR_IS_RANGE(*reg_prop))) {
262 next_command_buffer_entry->destination_cpu_selector.range.min_cpu = (uint8_t)CPU_SELECTOR_MIN_CPU(*reg_prop);
263 next_command_buffer_entry->destination_cpu_selector.range.max_cpu = (uint8_t)CPU_SELECTOR_MAX_CPU(*reg_prop);
264 } else {
265 next_command_buffer_entry->destination_cpu_selector.mask = (uint16_t)CPU_SELECTOR(*reg_prop);
266 }
267 next_command_buffer_entry++;
268 }
269 }
270
271 // null terminate the address field of the command to end it
272 (next_command_buffer_entry++)->address = 0;
273
274 // save pointer into table for this command
275 *command_buffer = command_starting_index;
276 }
277
278 static void
pe_run_debug_command(command_buffer_element_t * command_buffer)279 pe_run_debug_command(command_buffer_element_t *command_buffer)
280 {
281 if (!PE_arm_debug_and_trace_initialized()) {
282 /*
283 * In practice this can only happen if we panicked very early,
284 * when only the boot CPU is online and before it has finished
285 * initializing the debug and trace infrastructure. Avoid an
286 * unhelpful nested panic() here and instead resume execution
287 * to handle_debugger_trap(), which logs a user friendly error
288 * message before spinning forever.
289 */
290 return;
291 }
292
293 // When both the CPUs panic, one will get stuck on the lock and the other CPU will be halted when the first executes the debug command
294 simple_lock(&panic_hook_lock, LCK_GRP_NULL);
295
296 running_debug_command_on_cpu_number = cpu_number();
297
298 while (command_buffer && command_buffer->address) {
299 if (is_running_cpu_selected(command_buffer)) {
300 panic_trace_log("%s: cpu %d: reg write 0x%lx (VA 0x%lx):= 0x%lx",
301 __func__, running_debug_command_on_cpu_number, command_buffer->address_pa,
302 command_buffer->address, command_buffer->value);
303 if (command_buffer->is_32bit) {
304 *((volatile uint32_t*)(command_buffer->address)) = (uint32_t)(command_buffer->value);
305 } else {
306 *((volatile uintptr_t*)(command_buffer->address)) = command_buffer->value; // register = value;
307 }
308 if (command_buffer->delay_us != 0) {
309 uint64_t deadline;
310 nanoseconds_to_absolutetime(command_buffer->delay_us * NSEC_PER_USEC, &deadline);
311 deadline += ml_get_timebase();
312 while (ml_get_timebase() < deadline) {
313 os_compiler_barrier();
314 }
315 }
316 }
317 command_buffer++;
318 }
319
320 running_debug_command_on_cpu_number = -1;
321 simple_unlock(&panic_hook_lock);
322 }
323
324 #endif /* DEVELOPMENT || DEBUG */
325
326 /*****************
327 * Partial policy *
328 *****************/
329
330 /* Debug-only section. */
331 #if DEVELOPMENT || DEBUG
332
333 /* Util. */
334 #ifndef MIN
335 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
336 #endif /* MIN */
337
338 /*
339 * The % of devices which will have panic_trace enabled when using a partial
340 * enablement policy.
341 */
342 static TUNABLE_DT(uint32_t, panic_trace_partial_percent,
343 "/arm-io/cpu-debug-interface", "panic-trace-partial-percent",
344 "panic_trace_partial_percent", 50, TUNABLE_DT_NONE);
345
346 /*
347 * Stress racks opt out of panic_trace, unless overridden by the panic_trace boot-arg.
348 */
349 static void
panic_trace_apply_stress_rack_policy(void)350 panic_trace_apply_stress_rack_policy(void)
351 {
352 DTEntry ent = NULL;
353 DTEntry entryP = NULL;
354 const void *propP = NULL;
355 unsigned int size = 0;
356
357 if (SecureDTLookupEntry(NULL, "/chosen", &ent) == kSuccess &&
358 SecureDTGetProperty(ent, "stress-rack", &propP, &size) == kSuccess) {
359 (void)entryP;
360 if (PE_parse_boot_argn("panic_trace", NULL, 0)) {
361 // Prefer user specified boot-arg even when running on stress racks.
362 // Make an exception for devices with broken single-stepping.
363 } else {
364 panic_trace = 0;
365 }
366 }
367 }
368
369 /*
370 * When the `panic_trace_partial_policy` flag is set, not all devices will have
371 * the panic_trace settings applied. The actual % is determined by
372 * `panic_trace_partial_percent`.
373 * By using the ECID instead of a random number the process is made
374 * deterministic for any given device.
375 * This function disables panic trace if the device falls into the disabled %
376 * range. It otherwise leaves the panic_trace value unmodified.
377 * Called on the boot path, thus does not lock panic_trace_lock.
378 */
379 static void
panic_trace_apply_partial_policy(void)380 panic_trace_apply_partial_policy(void)
381 {
382 assert3u((panic_trace & panic_trace_partial_policy), !=, 0);
383
384 DTEntry ent = NULL;
385 unsigned int size = 0;
386 const void *ecid = NULL;
387
388 /* Grab the ECID. */
389 if (SecureDTLookupEntry(NULL, "/chosen", &ent) != kSuccess ||
390 SecureDTGetProperty(ent, "unique-chip-id", &ecid, &size) != kSuccess) {
391 panic_trace = panic_trace_disabled;
392 return;
393 }
394
395 /*
396 * Use os_hash_jenkins to convert the decidedly non-random ECID into
397 * something resembling a random number. Better (cryptographic) hash
398 * functions are not available at this point in boot.
399 */
400 const uint32_t rand = os_hash_jenkins(ecid, size);
401
402 /* Sanitize the percent value. */
403 const uint32_t percent = MIN(100, panic_trace_partial_percent);
404
405 /*
406 * Apply the ECID percent value. The bias here should be so tiny as to not
407 * matter for this purpose.
408 */
409 if ((rand % 100) >= percent) {
410 panic_trace = panic_trace_disabled;
411 }
412 }
413
414 #endif /* DEVELOPMENT || DEBUG */
415
416 /***************
417 * External API *
418 ***************/
419
420 #if DEVELOPMENT || DEBUG
421 void
PE_arm_debug_enable_trace(bool should_log)422 PE_arm_debug_enable_trace(bool should_log)
423 {
424 if (should_log) {
425 panic_trace_log("%s enter", __FUNCTION__);
426 }
427 if (panic_trace & panic_trace_enabled) {
428 pe_run_debug_command(enable_trace);
429 } else if (panic_trace & panic_trace_alt_enabled) {
430 pe_run_debug_command(enable_alt_trace);
431 }
432 if (should_log) {
433 panic_trace_log("%s exit", __FUNCTION__);
434 }
435 }
436 #endif /* DEVELOPMENT || DEBUG */
437
438 #if DEVELOPMENT || DEBUG
439 static void
PE_arm_panic_hook(const char * str __unused)440 PE_arm_panic_hook(const char *str __unused)
441 {
442 (void)str; // not used
443 #if defined(__arm64__) && !APPLEVIRTUALPLATFORM
444 /*
445 * For Fastsim support--inform the simulator that it can dump a
446 * panic trace now (so we don't capture all the panic handling).
447 * This constant is randomly chosen by agreement between xnu and
448 * Fastsim.
449 */
450 __asm__ volatile ("hint #0x4f");
451 #endif /* defined(__arm64__) && !APPLEVIRTUALPLATFORM */
452 if (bootarg_stop_clocks) {
453 pe_run_debug_command(stop_clocks);
454 }
455 // disable panic trace to snapshot its ringbuffer
456 // note: Not taking panic_trace_lock to avoid delaying cpu halt.
457 // This is known to be racy.
458 if (panic_trace) {
459 if (running_debug_command_on_cpu_number == cpu_number()) {
460 // This is going to end badly if we don't trap, since we'd be panic-ing during our own code
461 kprintf("## Panic Trace code caused the panic ##\n");
462 return; // allow the normal panic operation to occur.
463 }
464
465 // Stop tracing to freeze the buffer and return to normal panic processing.
466 pe_run_debug_command(trace_halt);
467 }
468 }
469 #endif /* DEVELOPMENT || DEBUG */
470
471
472 #if DEVELOPMENT || DEBUG
473 void (*PE_arm_debug_panic_hook)(const char *str) = PE_arm_panic_hook;
474 #else
475 void(*const PE_arm_debug_panic_hook)(const char *str) = NULL;
476 #endif // DEVELOPMENT || DEBUG
477
478 void
PE_init_cpu(void)479 PE_init_cpu(void)
480 {
481 #if DEVELOPMENT || DEBUG
482 if (bootarg_stop_clocks) {
483 pe_run_debug_command(enable_stop_clocks);
484 }
485 #endif // DEVELOPMENT || DEBUG
486
487 pe_init_fiq();
488 }
489
490
491 void
PE_singlestep_hook(void)492 PE_singlestep_hook(void)
493 {
494 }
495
496 void
PE_panic_hook(const char * str __unused)497 PE_panic_hook(const char *str __unused)
498 {
499 if (PE_arm_debug_panic_hook != NULL) {
500 PE_arm_debug_panic_hook(str);
501 }
502 }
503
504 /*
505 * Initialize the trace infrastructure.
506 */
507 void
pe_arm_init_debug(void * args)508 pe_arm_init_debug(void *args)
509 {
510 DTEntry entryP;
511 uintptr_t const *reg_prop;
512 uint32_t prop_size;
513
514 /*
515 * When args != NULL, this means we're being called from arm_init() on the
516 * boot CPU; this controls one-time init of the panic trace infrastructure.
517 * During one-time init, panic_trace_lock does not need to be held.
518 */
519 const bool is_boot_cpu = (args != NULL);
520
521 if (gSocPhys == 0) {
522 kprintf("pe_arm_init_debug: failed to initialize gSocPhys == 0\n");
523 return;
524 }
525
526 #if DEVELOPMENT || DEBUG
527 if (is_boot_cpu) {
528 if (panic_trace != 0) {
529 panic_trace_apply_stress_rack_policy();
530 }
531
532 if ((panic_trace & panic_trace_partial_policy) != 0) {
533 panic_trace_apply_partial_policy();
534 }
535 }
536 #endif /* DEVELOPMENT || DEBUG */
537
538 if (SecureDTFindEntry("device_type", "cpu-debug-interface", &entryP) == kSuccess) {
539 if (is_boot_cpu) {
540 if (SecureDTGetProperty(entryP, "reg", (void const **)®_prop, &prop_size) == kSuccess) {
541 ml_init_arm_debug_interface(args, ml_io_map(gSocPhys + *reg_prop, *(reg_prop + 1)));
542 }
543 #if DEVELOPMENT || DEBUG
544 simple_lock_init(&panic_hook_lock, 0); //assuming single threaded mode
545
546 if (panic_trace) {
547 kprintf("pe_arm_init_debug: panic_trace=%d\n", panic_trace);
548
549 // Prepare debug command buffers.
550 pe_init_debug_command(entryP, &cpu_halt, "cpu_halt");
551 pe_init_debug_command(entryP, &enable_trace, "enable_trace");
552 pe_init_debug_command(entryP, &enable_alt_trace, "enable_alt_trace");
553 pe_init_debug_command(entryP, &trace_halt, "trace_halt");
554
555 // start tracing now
556 PE_arm_debug_enable_trace(true);
557 }
558 if (bootarg_stop_clocks) {
559 pe_init_debug_command(entryP, &enable_stop_clocks, "enable_stop_clocks");
560 pe_init_debug_command(entryP, &stop_clocks, "stop_clocks");
561 }
562 #endif
563 }
564 } else {
565 #if DEVELOPMENT || DEBUG
566 const uint32_t dependent_modes = (panic_trace_enabled | panic_trace_alt_enabled);
567 if (is_boot_cpu && (bootarg_stop_clocks || (panic_trace & dependent_modes))) {
568 panic("failed to find cpu-debug-interface node in the EDT! "
569 "(required by `panic_trace={0x01, 0x10}` or `stop_clocks=1`)");
570 } else
571 #endif
572 {
573 kprintf("pe_arm_init_debug: failed to find cpu-debug-interface\n");
574 }
575 }
576
577
578 debug_and_trace_initialized = true;
579 }
580
581 /*********************
582 * Panic-trace sysctl *
583 *********************/
584
585