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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * arch/arm/kernel/unwind.c
4 *
5 * Copyright (C) 2008 ARM Limited
6 *
7 * Stack unwinding support for ARM
8 *
9 * An ARM EABI version of gcc is required to generate the unwind
10 * tables. For information about the structure of the unwind tables,
11 * see "Exception Handling ABI for the ARM Architecture" at:
12 *
13 * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
14 */
15
16#ifndef __CHECKER__
17#if !defined (__ARM_EABI__)
18#warning Your compiler does not have EABI support.
19#warning ARM unwind is known to compile only with EABI compilers.
20#warning Change compiler or disable ARM_UNWIND option.
21#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2) && !defined(__clang__)
22#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
23#warning Change compiler or disable ARM_UNWIND option.
24#endif
25#endif /* __CHECKER__ */
26
27#include <linux/kernel.h>
28#include <linux/init.h>
29#include <linux/export.h>
30#include <linux/sched.h>
31#include <linux/slab.h>
32#include <linux/spinlock.h>
33#include <linux/list.h>
34
35#include <asm/stacktrace.h>
36#include <asm/traps.h>
37#include <asm/unwind.h>
38
39/* Dummy functions to avoid linker complaints */
40void __aeabi_unwind_cpp_pr0(void)
41{
42};
43EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
44
45void __aeabi_unwind_cpp_pr1(void)
46{
47};
48EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
49
50void __aeabi_unwind_cpp_pr2(void)
51{
52};
53EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
54
55struct unwind_ctrl_block {
56 unsigned long vrs[16]; /* virtual register set */
57 const unsigned long *insn; /* pointer to the current instructions word */
58 unsigned long sp_high; /* highest value of sp allowed */
59 /*
60 * 1 : check for stack overflow for each register pop.
61 * 0 : save overhead if there is plenty of stack remaining.
62 */
63 int check_each_pop;
64 int entries; /* number of entries left to interpret */
65 int byte; /* current byte number in the instructions word */
66};
67
68enum regs {
69#ifdef CONFIG_THUMB2_KERNEL
70 FP = 7,
71#else
72 FP = 11,
73#endif
74 SP = 13,
75 LR = 14,
76 PC = 15
77};
78
79extern const struct unwind_idx __start_unwind_idx[];
80static const struct unwind_idx *__origin_unwind_idx;
81extern const struct unwind_idx __stop_unwind_idx[];
82
83static DEFINE_RAW_SPINLOCK(unwind_lock);
84static LIST_HEAD(unwind_tables);
85
86/* Convert a prel31 symbol to an absolute address */
87#define prel31_to_addr(ptr) \
88({ \
89 /* sign-extend to 32 bits */ \
90 long offset = (((long)*(ptr)) << 1) >> 1; \
91 (unsigned long)(ptr) + offset; \
92})
93
94/*
95 * Binary search in the unwind index. The entries are
96 * guaranteed to be sorted in ascending order by the linker.
97 *
98 * start = first entry
99 * origin = first entry with positive offset (or stop if there is no such entry)
100 * stop - 1 = last entry
101 */
102static const struct unwind_idx *search_index(unsigned long addr,
103 const struct unwind_idx *start,
104 const struct unwind_idx *origin,
105 const struct unwind_idx *stop)
106{
107 unsigned long addr_prel31;
108
109 pr_debug("%s(%08lx, %p, %p, %p)\n",
110 __func__, addr, start, origin, stop);
111
112 /*
113 * only search in the section with the matching sign. This way the
114 * prel31 numbers can be compared as unsigned longs.
115 */
116 if (addr < (unsigned long)start)
117 /* negative offsets: [start; origin) */
118 stop = origin;
119 else
120 /* positive offsets: [origin; stop) */
121 start = origin;
122
123 /* prel31 for address relavive to start */
124 addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;
125
126 while (start < stop - 1) {
127 const struct unwind_idx *mid = start + ((stop - start) >> 1);
128
129 /*
130 * As addr_prel31 is relative to start an offset is needed to
131 * make it relative to mid.
132 */
133 if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
134 mid->addr_offset)
135 stop = mid;
136 else {
137 /* keep addr_prel31 relative to start */
138 addr_prel31 -= ((unsigned long)mid -
139 (unsigned long)start);
140 start = mid;
141 }
142 }
143
144 if (likely(start->addr_offset <= addr_prel31))
145 return start;
146 else {
147 pr_warn("unwind: Unknown symbol address %08lx\n", addr);
148 return NULL;
149 }
150}
151
152static const struct unwind_idx *unwind_find_origin(
153 const struct unwind_idx *start, const struct unwind_idx *stop)
154{
155 pr_debug("%s(%p, %p)\n", __func__, start, stop);
156 while (start < stop) {
157 const struct unwind_idx *mid = start + ((stop - start) >> 1);
158
159 if (mid->addr_offset >= 0x40000000)
160 /* negative offset */
161 start = mid + 1;
162 else
163 /* positive offset */
164 stop = mid;
165 }
166 pr_debug("%s -> %p\n", __func__, stop);
167 return stop;
168}
169
170static const struct unwind_idx *unwind_find_idx(unsigned long addr)
171{
172 const struct unwind_idx *idx = NULL;
173 unsigned long flags;
174
175 pr_debug("%s(%08lx)\n", __func__, addr);
176
177 if (core_kernel_text(addr)) {
178 if (unlikely(!__origin_unwind_idx))
179 __origin_unwind_idx =
180 unwind_find_origin(__start_unwind_idx,
181 __stop_unwind_idx);
182
183 /* main unwind table */
184 idx = search_index(addr, __start_unwind_idx,
185 __origin_unwind_idx,
186 __stop_unwind_idx);
187 } else {
188 /* module unwind tables */
189 struct unwind_table *table;
190
191 raw_spin_lock_irqsave(&unwind_lock, flags);
192 list_for_each_entry(table, &unwind_tables, list) {
193 if (addr >= table->begin_addr &&
194 addr < table->end_addr) {
195 idx = search_index(addr, table->start,
196 table->origin,
197 table->stop);
198 /* Move-to-front to exploit common traces */
199 list_move(&table->list, &unwind_tables);
200 break;
201 }
202 }
203 raw_spin_unlock_irqrestore(&unwind_lock, flags);
204 }
205
206 pr_debug("%s: idx = %p\n", __func__, idx);
207 return idx;
208}
209
210static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
211{
212 unsigned long ret;
213
214 if (ctrl->entries <= 0) {
215 pr_warn("unwind: Corrupt unwind table\n");
216 return 0;
217 }
218
219 ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff;
220
221 if (ctrl->byte == 0) {
222 ctrl->insn++;
223 ctrl->entries--;
224 ctrl->byte = 3;
225 } else
226 ctrl->byte--;
227
228 return ret;
229}
230
231/* Before poping a register check whether it is feasible or not */
232static int unwind_pop_register(struct unwind_ctrl_block *ctrl,
233 unsigned long **vsp, unsigned int reg)
234{
235 if (unlikely(ctrl->check_each_pop))
236 if (*vsp >= (unsigned long *)ctrl->sp_high)
237 return -URC_FAILURE;
238
239 ctrl->vrs[reg] = *(*vsp)++;
240 return URC_OK;
241}
242
243/* Helper functions to execute the instructions */
244static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl,
245 unsigned long mask)
246{
247 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
248 int load_sp, reg = 4;
249
250 load_sp = mask & (1 << (13 - 4));
251 while (mask) {
252 if (mask & 1)
253 if (unwind_pop_register(ctrl, &vsp, reg))
254 return -URC_FAILURE;
255 mask >>= 1;
256 reg++;
257 }
258 if (!load_sp)
259 ctrl->vrs[SP] = (unsigned long)vsp;
260
261 return URC_OK;
262}
263
264static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl,
265 unsigned long insn)
266{
267 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
268 int reg;
269
270 /* pop R4-R[4+bbb] */
271 for (reg = 4; reg <= 4 + (insn & 7); reg++)
272 if (unwind_pop_register(ctrl, &vsp, reg))
273 return -URC_FAILURE;
274
275 if (insn & 0x8)
276 if (unwind_pop_register(ctrl, &vsp, 14))
277 return -URC_FAILURE;
278
279 ctrl->vrs[SP] = (unsigned long)vsp;
280
281 return URC_OK;
282}
283
284static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl,
285 unsigned long mask)
286{
287 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
288 int reg = 0;
289
290 /* pop R0-R3 according to mask */
291 while (mask) {
292 if (mask & 1)
293 if (unwind_pop_register(ctrl, &vsp, reg))
294 return -URC_FAILURE;
295 mask >>= 1;
296 reg++;
297 }
298 ctrl->vrs[SP] = (unsigned long)vsp;
299
300 return URC_OK;
301}
302
303/*
304 * Execute the current unwind instruction.
305 */
306static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
307{
308 unsigned long insn = unwind_get_byte(ctrl);
309 int ret = URC_OK;
310
311 pr_debug("%s: insn = %08lx\n", __func__, insn);
312
313 if ((insn & 0xc0) == 0x00)
314 ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
315 else if ((insn & 0xc0) == 0x40)
316 ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
317 else if ((insn & 0xf0) == 0x80) {
318 unsigned long mask;
319
320 insn = (insn << 8) | unwind_get_byte(ctrl);
321 mask = insn & 0x0fff;
322 if (mask == 0) {
323 pr_warn("unwind: 'Refuse to unwind' instruction %04lx\n",
324 insn);
325 return -URC_FAILURE;
326 }
327
328 ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask);
329 if (ret)
330 goto error;
331 } else if ((insn & 0xf0) == 0x90 &&
332 (insn & 0x0d) != 0x0d)
333 ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
334 else if ((insn & 0xf0) == 0xa0) {
335 ret = unwind_exec_pop_r4_to_rN(ctrl, insn);
336 if (ret)
337 goto error;
338 } else if (insn == 0xb0) {
339 if (ctrl->vrs[PC] == 0)
340 ctrl->vrs[PC] = ctrl->vrs[LR];
341 /* no further processing */
342 ctrl->entries = 0;
343 } else if (insn == 0xb1) {
344 unsigned long mask = unwind_get_byte(ctrl);
345
346 if (mask == 0 || mask & 0xf0) {
347 pr_warn("unwind: Spare encoding %04lx\n",
348 (insn << 8) | mask);
349 return -URC_FAILURE;
350 }
351
352 ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask);
353 if (ret)
354 goto error;
355 } else if (insn == 0xb2) {
356 unsigned long uleb128 = unwind_get_byte(ctrl);
357
358 ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
359 } else {
360 pr_warn("unwind: Unhandled instruction %02lx\n", insn);
361 return -URC_FAILURE;
362 }
363
364 pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
365 ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
366
367error:
368 return ret;
369}
370
371/*
372 * Unwind a single frame starting with *sp for the symbol at *pc. It
373 * updates the *pc and *sp with the new values.
374 */
375int unwind_frame(struct stackframe *frame)
376{
377 unsigned long low;
378 const struct unwind_idx *idx;
379 struct unwind_ctrl_block ctrl;
380
381 /* store the highest address on the stack to avoid crossing it*/
382 low = frame->sp;
383 ctrl.sp_high = ALIGN(low, THREAD_SIZE);
384
385 pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
386 frame->pc, frame->lr, frame->sp);
387
388 if (!kernel_text_address(frame->pc))
389 return -URC_FAILURE;
390
391 idx = unwind_find_idx(frame->pc);
392 if (!idx) {
393 pr_warn("unwind: Index not found %08lx\n", frame->pc);
394 return -URC_FAILURE;
395 }
396
397 ctrl.vrs[FP] = frame->fp;
398 ctrl.vrs[SP] = frame->sp;
399 ctrl.vrs[LR] = frame->lr;
400 ctrl.vrs[PC] = 0;
401
402 if (idx->insn == 1)
403 /* can't unwind */
404 return -URC_FAILURE;
405 else if ((idx->insn & 0x80000000) == 0)
406 /* prel31 to the unwind table */
407 ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
408 else if ((idx->insn & 0xff000000) == 0x80000000)
409 /* only personality routine 0 supported in the index */
410 ctrl.insn = &idx->insn;
411 else {
412 pr_warn("unwind: Unsupported personality routine %08lx in the index at %p\n",
413 idx->insn, idx);
414 return -URC_FAILURE;
415 }
416
417 /* check the personality routine */
418 if ((*ctrl.insn & 0xff000000) == 0x80000000) {
419 ctrl.byte = 2;
420 ctrl.entries = 1;
421 } else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
422 ctrl.byte = 1;
423 ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
424 } else {
425 pr_warn("unwind: Unsupported personality routine %08lx at %p\n",
426 *ctrl.insn, ctrl.insn);
427 return -URC_FAILURE;
428 }
429
430 ctrl.check_each_pop = 0;
431
432 while (ctrl.entries > 0) {
433 int urc;
434 if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs))
435 ctrl.check_each_pop = 1;
436 urc = unwind_exec_insn(&ctrl);
437 if (urc < 0)
438 return urc;
439 if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high)
440 return -URC_FAILURE;
441 }
442
443 if (ctrl.vrs[PC] == 0)
444 ctrl.vrs[PC] = ctrl.vrs[LR];
445
446 /* check for infinite loop */
447 if (frame->pc == ctrl.vrs[PC] && frame->sp == ctrl.vrs[SP])
448 return -URC_FAILURE;
449
450 frame->fp = ctrl.vrs[FP];
451 frame->sp = ctrl.vrs[SP];
452 frame->lr = ctrl.vrs[LR];
453 frame->pc = ctrl.vrs[PC];
454
455 return URC_OK;
456}
457
458void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk,
459 const char *loglvl)
460{
461 struct stackframe frame;
462
463 pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
464
465 if (!tsk)
466 tsk = current;
467
468 if (regs) {
469 arm_get_current_stackframe(regs, &frame);
470 /* PC might be corrupted, use LR in that case. */
471 if (!kernel_text_address(regs->ARM_pc))
472 frame.pc = regs->ARM_lr;
473 } else if (tsk == current) {
474 frame.fp = (unsigned long)__builtin_frame_address(0);
475 frame.sp = current_stack_pointer;
476 frame.lr = (unsigned long)__builtin_return_address(0);
477 frame.pc = (unsigned long)unwind_backtrace;
478 } else {
479 /* task blocked in __switch_to */
480 frame.fp = thread_saved_fp(tsk);
481 frame.sp = thread_saved_sp(tsk);
482 /*
483 * The function calling __switch_to cannot be a leaf function
484 * so LR is recovered from the stack.
485 */
486 frame.lr = 0;
487 frame.pc = thread_saved_pc(tsk);
488 }
489
490 while (1) {
491 int urc;
492 unsigned long where = frame.pc;
493
494 urc = unwind_frame(&frame);
495 if (urc < 0)
496 break;
497 dump_backtrace_entry(where, frame.pc, frame.sp - 4, loglvl);
498 }
499}
500
501struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
502 unsigned long text_addr,
503 unsigned long text_size)
504{
505 unsigned long flags;
506 struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);
507
508 pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
509 text_addr, text_size);
510
511 if (!tab)
512 return tab;
513
514 tab->start = (const struct unwind_idx *)start;
515 tab->stop = (const struct unwind_idx *)(start + size);
516 tab->origin = unwind_find_origin(tab->start, tab->stop);
517 tab->begin_addr = text_addr;
518 tab->end_addr = text_addr + text_size;
519
520 raw_spin_lock_irqsave(&unwind_lock, flags);
521 list_add_tail(&tab->list, &unwind_tables);
522 raw_spin_unlock_irqrestore(&unwind_lock, flags);
523
524 return tab;
525}
526
527void unwind_table_del(struct unwind_table *tab)
528{
529 unsigned long flags;
530
531 if (!tab)
532 return;
533
534 raw_spin_lock_irqsave(&unwind_lock, flags);
535 list_del(&tab->list);
536 raw_spin_unlock_irqrestore(&unwind_lock, flags);
537
538 kfree(tab);
539}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * arch/arm/kernel/unwind.c
4 *
5 * Copyright (C) 2008 ARM Limited
6 *
7 * Stack unwinding support for ARM
8 *
9 * An ARM EABI version of gcc is required to generate the unwind
10 * tables. For information about the structure of the unwind tables,
11 * see "Exception Handling ABI for the ARM Architecture" at:
12 *
13 * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
14 */
15
16#ifndef __CHECKER__
17#if !defined (__ARM_EABI__)
18#warning Your compiler does not have EABI support.
19#warning ARM unwind is known to compile only with EABI compilers.
20#warning Change compiler or disable ARM_UNWIND option.
21#endif
22#endif /* __CHECKER__ */
23
24#include <linux/kernel.h>
25#include <linux/init.h>
26#include <linux/export.h>
27#include <linux/sched.h>
28#include <linux/slab.h>
29#include <linux/spinlock.h>
30#include <linux/list.h>
31#include <linux/module.h>
32
33#include <asm/stacktrace.h>
34#include <asm/traps.h>
35#include <asm/unwind.h>
36
37#include "reboot.h"
38
39/* Dummy functions to avoid linker complaints */
40void __aeabi_unwind_cpp_pr0(void)
41{
42};
43EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
44
45void __aeabi_unwind_cpp_pr1(void)
46{
47};
48EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
49
50void __aeabi_unwind_cpp_pr2(void)
51{
52};
53EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
54
55struct unwind_ctrl_block {
56 unsigned long vrs[16]; /* virtual register set */
57 const unsigned long *insn; /* pointer to the current instructions word */
58 unsigned long sp_high; /* highest value of sp allowed */
59 unsigned long *lr_addr; /* address of LR value on the stack */
60 /*
61 * 1 : check for stack overflow for each register pop.
62 * 0 : save overhead if there is plenty of stack remaining.
63 */
64 int check_each_pop;
65 int entries; /* number of entries left to interpret */
66 int byte; /* current byte number in the instructions word */
67};
68
69enum regs {
70#ifdef CONFIG_THUMB2_KERNEL
71 FP = 7,
72#else
73 FP = 11,
74#endif
75 SP = 13,
76 LR = 14,
77 PC = 15
78};
79
80extern const struct unwind_idx __start_unwind_idx[];
81static const struct unwind_idx *__origin_unwind_idx;
82extern const struct unwind_idx __stop_unwind_idx[];
83
84static DEFINE_RAW_SPINLOCK(unwind_lock);
85static LIST_HEAD(unwind_tables);
86
87/* Convert a prel31 symbol to an absolute address */
88#define prel31_to_addr(ptr) \
89({ \
90 /* sign-extend to 32 bits */ \
91 long offset = (((long)*(ptr)) << 1) >> 1; \
92 (unsigned long)(ptr) + offset; \
93})
94
95/*
96 * Binary search in the unwind index. The entries are
97 * guaranteed to be sorted in ascending order by the linker.
98 *
99 * start = first entry
100 * origin = first entry with positive offset (or stop if there is no such entry)
101 * stop - 1 = last entry
102 */
103static const struct unwind_idx *search_index(unsigned long addr,
104 const struct unwind_idx *start,
105 const struct unwind_idx *origin,
106 const struct unwind_idx *stop)
107{
108 unsigned long addr_prel31;
109
110 pr_debug("%s(%08lx, %p, %p, %p)\n",
111 __func__, addr, start, origin, stop);
112
113 /*
114 * only search in the section with the matching sign. This way the
115 * prel31 numbers can be compared as unsigned longs.
116 */
117 if (addr < (unsigned long)start)
118 /* negative offsets: [start; origin) */
119 stop = origin;
120 else
121 /* positive offsets: [origin; stop) */
122 start = origin;
123
124 /* prel31 for address relavive to start */
125 addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;
126
127 while (start < stop - 1) {
128 const struct unwind_idx *mid = start + ((stop - start) >> 1);
129
130 /*
131 * As addr_prel31 is relative to start an offset is needed to
132 * make it relative to mid.
133 */
134 if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
135 mid->addr_offset)
136 stop = mid;
137 else {
138 /* keep addr_prel31 relative to start */
139 addr_prel31 -= ((unsigned long)mid -
140 (unsigned long)start);
141 start = mid;
142 }
143 }
144
145 if (likely(start->addr_offset <= addr_prel31))
146 return start;
147 else {
148 pr_warn("unwind: Unknown symbol address %08lx\n", addr);
149 return NULL;
150 }
151}
152
153static const struct unwind_idx *unwind_find_origin(
154 const struct unwind_idx *start, const struct unwind_idx *stop)
155{
156 pr_debug("%s(%p, %p)\n", __func__, start, stop);
157 while (start < stop) {
158 const struct unwind_idx *mid = start + ((stop - start) >> 1);
159
160 if (mid->addr_offset >= 0x40000000)
161 /* negative offset */
162 start = mid + 1;
163 else
164 /* positive offset */
165 stop = mid;
166 }
167 pr_debug("%s -> %p\n", __func__, stop);
168 return stop;
169}
170
171static const struct unwind_idx *unwind_find_idx(unsigned long addr)
172{
173 const struct unwind_idx *idx = NULL;
174 unsigned long flags;
175
176 pr_debug("%s(%08lx)\n", __func__, addr);
177
178 if (core_kernel_text(addr)) {
179 if (unlikely(!__origin_unwind_idx))
180 __origin_unwind_idx =
181 unwind_find_origin(__start_unwind_idx,
182 __stop_unwind_idx);
183
184 /* main unwind table */
185 idx = search_index(addr, __start_unwind_idx,
186 __origin_unwind_idx,
187 __stop_unwind_idx);
188 } else {
189 /* module unwind tables */
190 struct unwind_table *table;
191
192 raw_spin_lock_irqsave(&unwind_lock, flags);
193 list_for_each_entry(table, &unwind_tables, list) {
194 if (addr >= table->begin_addr &&
195 addr < table->end_addr) {
196 idx = search_index(addr, table->start,
197 table->origin,
198 table->stop);
199 /* Move-to-front to exploit common traces */
200 list_move(&table->list, &unwind_tables);
201 break;
202 }
203 }
204 raw_spin_unlock_irqrestore(&unwind_lock, flags);
205 }
206
207 pr_debug("%s: idx = %p\n", __func__, idx);
208 return idx;
209}
210
211static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
212{
213 unsigned long ret;
214
215 if (ctrl->entries <= 0) {
216 pr_warn("unwind: Corrupt unwind table\n");
217 return 0;
218 }
219
220 ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff;
221
222 if (ctrl->byte == 0) {
223 ctrl->insn++;
224 ctrl->entries--;
225 ctrl->byte = 3;
226 } else
227 ctrl->byte--;
228
229 return ret;
230}
231
232/* Before poping a register check whether it is feasible or not */
233static int unwind_pop_register(struct unwind_ctrl_block *ctrl,
234 unsigned long **vsp, unsigned int reg)
235{
236 if (unlikely(ctrl->check_each_pop))
237 if (*vsp >= (unsigned long *)ctrl->sp_high)
238 return -URC_FAILURE;
239
240 /* Use READ_ONCE_NOCHECK here to avoid this memory access
241 * from being tracked by KASAN.
242 */
243 ctrl->vrs[reg] = READ_ONCE_NOCHECK(*(*vsp));
244 if (reg == 14)
245 ctrl->lr_addr = *vsp;
246 (*vsp)++;
247 return URC_OK;
248}
249
250/* Helper functions to execute the instructions */
251static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl,
252 unsigned long mask)
253{
254 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
255 int load_sp, reg = 4;
256
257 load_sp = mask & (1 << (13 - 4));
258 while (mask) {
259 if (mask & 1)
260 if (unwind_pop_register(ctrl, &vsp, reg))
261 return -URC_FAILURE;
262 mask >>= 1;
263 reg++;
264 }
265 if (!load_sp) {
266 ctrl->vrs[SP] = (unsigned long)vsp;
267 }
268
269 return URC_OK;
270}
271
272static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl,
273 unsigned long insn)
274{
275 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
276 int reg;
277
278 /* pop R4-R[4+bbb] */
279 for (reg = 4; reg <= 4 + (insn & 7); reg++)
280 if (unwind_pop_register(ctrl, &vsp, reg))
281 return -URC_FAILURE;
282
283 if (insn & 0x8)
284 if (unwind_pop_register(ctrl, &vsp, 14))
285 return -URC_FAILURE;
286
287 ctrl->vrs[SP] = (unsigned long)vsp;
288
289 return URC_OK;
290}
291
292static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl,
293 unsigned long mask)
294{
295 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
296 int reg = 0;
297
298 /* pop R0-R3 according to mask */
299 while (mask) {
300 if (mask & 1)
301 if (unwind_pop_register(ctrl, &vsp, reg))
302 return -URC_FAILURE;
303 mask >>= 1;
304 reg++;
305 }
306 ctrl->vrs[SP] = (unsigned long)vsp;
307
308 return URC_OK;
309}
310
311/*
312 * Execute the current unwind instruction.
313 */
314static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
315{
316 unsigned long insn = unwind_get_byte(ctrl);
317 int ret = URC_OK;
318
319 pr_debug("%s: insn = %08lx\n", __func__, insn);
320
321 if ((insn & 0xc0) == 0x00)
322 ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
323 else if ((insn & 0xc0) == 0x40) {
324 ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
325 } else if ((insn & 0xf0) == 0x80) {
326 unsigned long mask;
327
328 insn = (insn << 8) | unwind_get_byte(ctrl);
329 mask = insn & 0x0fff;
330 if (mask == 0) {
331 pr_warn("unwind: 'Refuse to unwind' instruction %04lx\n",
332 insn);
333 return -URC_FAILURE;
334 }
335
336 ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask);
337 if (ret)
338 goto error;
339 } else if ((insn & 0xf0) == 0x90 &&
340 (insn & 0x0d) != 0x0d) {
341 ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
342 } else if ((insn & 0xf0) == 0xa0) {
343 ret = unwind_exec_pop_r4_to_rN(ctrl, insn);
344 if (ret)
345 goto error;
346 } else if (insn == 0xb0) {
347 if (ctrl->vrs[PC] == 0)
348 ctrl->vrs[PC] = ctrl->vrs[LR];
349 /* no further processing */
350 ctrl->entries = 0;
351 } else if (insn == 0xb1) {
352 unsigned long mask = unwind_get_byte(ctrl);
353
354 if (mask == 0 || mask & 0xf0) {
355 pr_warn("unwind: Spare encoding %04lx\n",
356 (insn << 8) | mask);
357 return -URC_FAILURE;
358 }
359
360 ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask);
361 if (ret)
362 goto error;
363 } else if (insn == 0xb2) {
364 unsigned long uleb128 = unwind_get_byte(ctrl);
365
366 ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
367 } else {
368 pr_warn("unwind: Unhandled instruction %02lx\n", insn);
369 return -URC_FAILURE;
370 }
371
372 pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
373 ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
374
375error:
376 return ret;
377}
378
379/*
380 * Unwind a single frame starting with *sp for the symbol at *pc. It
381 * updates the *pc and *sp with the new values.
382 */
383int unwind_frame(struct stackframe *frame)
384{
385 const struct unwind_idx *idx;
386 struct unwind_ctrl_block ctrl;
387 unsigned long sp_low;
388
389 /* store the highest address on the stack to avoid crossing it*/
390 sp_low = frame->sp;
391 ctrl.sp_high = ALIGN(sp_low - THREAD_SIZE, THREAD_ALIGN)
392 + THREAD_SIZE;
393
394 pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
395 frame->pc, frame->lr, frame->sp);
396
397 idx = unwind_find_idx(frame->pc);
398 if (!idx) {
399 if (frame->pc && kernel_text_address(frame->pc)) {
400 if (in_module_plt(frame->pc) && frame->pc != frame->lr) {
401 /*
402 * Quoting Ard: Veneers only set PC using a
403 * PC+immediate LDR, and so they don't affect
404 * the state of the stack or the register file
405 */
406 frame->pc = frame->lr;
407 return URC_OK;
408 }
409 pr_warn("unwind: Index not found %08lx\n", frame->pc);
410 }
411 return -URC_FAILURE;
412 }
413
414 ctrl.vrs[FP] = frame->fp;
415 ctrl.vrs[SP] = frame->sp;
416 ctrl.vrs[LR] = frame->lr;
417 ctrl.vrs[PC] = 0;
418
419 if (idx->insn == 1)
420 /* can't unwind */
421 return -URC_FAILURE;
422 else if (frame->pc == prel31_to_addr(&idx->addr_offset)) {
423 /*
424 * Unwinding is tricky when we're halfway through the prologue,
425 * since the stack frame that the unwinder expects may not be
426 * fully set up yet. However, one thing we do know for sure is
427 * that if we are unwinding from the very first instruction of
428 * a function, we are still effectively in the stack frame of
429 * the caller, and the unwind info has no relevance yet.
430 */
431 if (frame->pc == frame->lr)
432 return -URC_FAILURE;
433 frame->pc = frame->lr;
434 return URC_OK;
435 } else if ((idx->insn & 0x80000000) == 0)
436 /* prel31 to the unwind table */
437 ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
438 else if ((idx->insn & 0xff000000) == 0x80000000)
439 /* only personality routine 0 supported in the index */
440 ctrl.insn = &idx->insn;
441 else {
442 pr_warn("unwind: Unsupported personality routine %08lx in the index at %p\n",
443 idx->insn, idx);
444 return -URC_FAILURE;
445 }
446
447 /* check the personality routine */
448 if ((*ctrl.insn & 0xff000000) == 0x80000000) {
449 ctrl.byte = 2;
450 ctrl.entries = 1;
451 } else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
452 ctrl.byte = 1;
453 ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
454 } else {
455 pr_warn("unwind: Unsupported personality routine %08lx at %p\n",
456 *ctrl.insn, ctrl.insn);
457 return -URC_FAILURE;
458 }
459
460 ctrl.check_each_pop = 0;
461
462 if (prel31_to_addr(&idx->addr_offset) == (u32)&call_with_stack) {
463 /*
464 * call_with_stack() is the only place where we permit SP to
465 * jump from one stack to another, and since we know it is
466 * guaranteed to happen, set up the SP bounds accordingly.
467 */
468 sp_low = frame->fp;
469 ctrl.sp_high = ALIGN(frame->fp, THREAD_SIZE);
470 }
471
472 while (ctrl.entries > 0) {
473 int urc;
474 if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs))
475 ctrl.check_each_pop = 1;
476 urc = unwind_exec_insn(&ctrl);
477 if (urc < 0)
478 return urc;
479 if (ctrl.vrs[SP] < sp_low || ctrl.vrs[SP] > ctrl.sp_high)
480 return -URC_FAILURE;
481 }
482
483 if (ctrl.vrs[PC] == 0)
484 ctrl.vrs[PC] = ctrl.vrs[LR];
485
486 /* check for infinite loop */
487 if (frame->pc == ctrl.vrs[PC] && frame->sp == ctrl.vrs[SP])
488 return -URC_FAILURE;
489
490 frame->fp = ctrl.vrs[FP];
491 frame->sp = ctrl.vrs[SP];
492 frame->lr = ctrl.vrs[LR];
493 frame->pc = ctrl.vrs[PC];
494 frame->lr_addr = ctrl.lr_addr;
495
496 return URC_OK;
497}
498
499void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk,
500 const char *loglvl)
501{
502 struct stackframe frame;
503
504 pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
505
506 if (!tsk)
507 tsk = current;
508
509 if (regs) {
510 arm_get_current_stackframe(regs, &frame);
511 /* PC might be corrupted, use LR in that case. */
512 if (!kernel_text_address(regs->ARM_pc))
513 frame.pc = regs->ARM_lr;
514 } else if (tsk == current) {
515 frame.fp = (unsigned long)__builtin_frame_address(0);
516 frame.sp = current_stack_pointer;
517 frame.lr = (unsigned long)__builtin_return_address(0);
518 /* We are saving the stack and execution state at this
519 * point, so we should ensure that frame.pc is within
520 * this block of code.
521 */
522here:
523 frame.pc = (unsigned long)&&here;
524 } else {
525 /* task blocked in __switch_to */
526 frame.fp = thread_saved_fp(tsk);
527 frame.sp = thread_saved_sp(tsk);
528 /*
529 * The function calling __switch_to cannot be a leaf function
530 * so LR is recovered from the stack.
531 */
532 frame.lr = 0;
533 frame.pc = thread_saved_pc(tsk);
534 }
535
536 while (1) {
537 int urc;
538 unsigned long where = frame.pc;
539
540 urc = unwind_frame(&frame);
541 if (urc < 0)
542 break;
543 dump_backtrace_entry(where, frame.pc, frame.sp - 4, loglvl);
544 }
545}
546
547struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
548 unsigned long text_addr,
549 unsigned long text_size)
550{
551 unsigned long flags;
552 struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);
553
554 pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
555 text_addr, text_size);
556
557 if (!tab)
558 return tab;
559
560 tab->start = (const struct unwind_idx *)start;
561 tab->stop = (const struct unwind_idx *)(start + size);
562 tab->origin = unwind_find_origin(tab->start, tab->stop);
563 tab->begin_addr = text_addr;
564 tab->end_addr = text_addr + text_size;
565
566 raw_spin_lock_irqsave(&unwind_lock, flags);
567 list_add_tail(&tab->list, &unwind_tables);
568 raw_spin_unlock_irqrestore(&unwind_lock, flags);
569
570 return tab;
571}
572
573void unwind_table_del(struct unwind_table *tab)
574{
575 unsigned long flags;
576
577 if (!tab)
578 return;
579
580 raw_spin_lock_irqsave(&unwind_lock, flags);
581 list_del(&tab->list);
582 raw_spin_unlock_irqrestore(&unwind_lock, flags);
583
584 kfree(tab);
585}