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1/*
2 * arch/arm/kernel/unwind.c
3 *
4 * Copyright (C) 2008 ARM Limited
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 *
20 * Stack unwinding support for ARM
21 *
22 * An ARM EABI version of gcc is required to generate the unwind
23 * tables. For information about the structure of the unwind tables,
24 * see "Exception Handling ABI for the ARM Architecture" at:
25 *
26 * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
27 */
28
29#ifndef __CHECKER__
30#if !defined (__ARM_EABI__)
31#warning Your compiler does not have EABI support.
32#warning ARM unwind is known to compile only with EABI compilers.
33#warning Change compiler or disable ARM_UNWIND option.
34#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2)
35#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
36#warning Change compiler or disable ARM_UNWIND option.
37#endif
38#endif /* __CHECKER__ */
39
40#include <linux/kernel.h>
41#include <linux/init.h>
42#include <linux/module.h>
43#include <linux/sched.h>
44#include <linux/slab.h>
45#include <linux/spinlock.h>
46#include <linux/list.h>
47
48#include <asm/stacktrace.h>
49#include <asm/traps.h>
50#include <asm/unwind.h>
51
52/* Dummy functions to avoid linker complaints */
53void __aeabi_unwind_cpp_pr0(void)
54{
55};
56EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
57
58void __aeabi_unwind_cpp_pr1(void)
59{
60};
61EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
62
63void __aeabi_unwind_cpp_pr2(void)
64{
65};
66EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
67
68struct unwind_ctrl_block {
69 unsigned long vrs[16]; /* virtual register set */
70 unsigned long *insn; /* pointer to the current instructions word */
71 int entries; /* number of entries left to interpret */
72 int byte; /* current byte number in the instructions word */
73};
74
75enum regs {
76#ifdef CONFIG_THUMB2_KERNEL
77 FP = 7,
78#else
79 FP = 11,
80#endif
81 SP = 13,
82 LR = 14,
83 PC = 15
84};
85
86extern struct unwind_idx __start_unwind_idx[];
87extern struct unwind_idx __stop_unwind_idx[];
88
89static DEFINE_SPINLOCK(unwind_lock);
90static LIST_HEAD(unwind_tables);
91
92/* Convert a prel31 symbol to an absolute address */
93#define prel31_to_addr(ptr) \
94({ \
95 /* sign-extend to 32 bits */ \
96 long offset = (((long)*(ptr)) << 1) >> 1; \
97 (unsigned long)(ptr) + offset; \
98})
99
100/*
101 * Binary search in the unwind index. The entries entries are
102 * guaranteed to be sorted in ascending order by the linker.
103 */
104static struct unwind_idx *search_index(unsigned long addr,
105 struct unwind_idx *first,
106 struct unwind_idx *last)
107{
108 pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);
109
110 if (addr < first->addr) {
111 pr_warning("unwind: Unknown symbol address %08lx\n", addr);
112 return NULL;
113 } else if (addr >= last->addr)
114 return last;
115
116 while (first < last - 1) {
117 struct unwind_idx *mid = first + ((last - first + 1) >> 1);
118
119 if (addr < mid->addr)
120 last = mid;
121 else
122 first = mid;
123 }
124
125 return first;
126}
127
128static struct unwind_idx *unwind_find_idx(unsigned long addr)
129{
130 struct unwind_idx *idx = NULL;
131 unsigned long flags;
132
133 pr_debug("%s(%08lx)\n", __func__, addr);
134
135 if (core_kernel_text(addr))
136 /* main unwind table */
137 idx = search_index(addr, __start_unwind_idx,
138 __stop_unwind_idx - 1);
139 else {
140 /* module unwind tables */
141 struct unwind_table *table;
142
143 spin_lock_irqsave(&unwind_lock, flags);
144 list_for_each_entry(table, &unwind_tables, list) {
145 if (addr >= table->begin_addr &&
146 addr < table->end_addr) {
147 idx = search_index(addr, table->start,
148 table->stop - 1);
149 /* Move-to-front to exploit common traces */
150 list_move(&table->list, &unwind_tables);
151 break;
152 }
153 }
154 spin_unlock_irqrestore(&unwind_lock, flags);
155 }
156
157 pr_debug("%s: idx = %p\n", __func__, idx);
158 return idx;
159}
160
161static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
162{
163 unsigned long ret;
164
165 if (ctrl->entries <= 0) {
166 pr_warning("unwind: Corrupt unwind table\n");
167 return 0;
168 }
169
170 ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff;
171
172 if (ctrl->byte == 0) {
173 ctrl->insn++;
174 ctrl->entries--;
175 ctrl->byte = 3;
176 } else
177 ctrl->byte--;
178
179 return ret;
180}
181
182/*
183 * Execute the current unwind instruction.
184 */
185static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
186{
187 unsigned long insn = unwind_get_byte(ctrl);
188
189 pr_debug("%s: insn = %08lx\n", __func__, insn);
190
191 if ((insn & 0xc0) == 0x00)
192 ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
193 else if ((insn & 0xc0) == 0x40)
194 ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
195 else if ((insn & 0xf0) == 0x80) {
196 unsigned long mask;
197 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
198 int load_sp, reg = 4;
199
200 insn = (insn << 8) | unwind_get_byte(ctrl);
201 mask = insn & 0x0fff;
202 if (mask == 0) {
203 pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
204 insn);
205 return -URC_FAILURE;
206 }
207
208 /* pop R4-R15 according to mask */
209 load_sp = mask & (1 << (13 - 4));
210 while (mask) {
211 if (mask & 1)
212 ctrl->vrs[reg] = *vsp++;
213 mask >>= 1;
214 reg++;
215 }
216 if (!load_sp)
217 ctrl->vrs[SP] = (unsigned long)vsp;
218 } else if ((insn & 0xf0) == 0x90 &&
219 (insn & 0x0d) != 0x0d)
220 ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
221 else if ((insn & 0xf0) == 0xa0) {
222 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
223 int reg;
224
225 /* pop R4-R[4+bbb] */
226 for (reg = 4; reg <= 4 + (insn & 7); reg++)
227 ctrl->vrs[reg] = *vsp++;
228 if (insn & 0x80)
229 ctrl->vrs[14] = *vsp++;
230 ctrl->vrs[SP] = (unsigned long)vsp;
231 } else if (insn == 0xb0) {
232 if (ctrl->vrs[PC] == 0)
233 ctrl->vrs[PC] = ctrl->vrs[LR];
234 /* no further processing */
235 ctrl->entries = 0;
236 } else if (insn == 0xb1) {
237 unsigned long mask = unwind_get_byte(ctrl);
238 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
239 int reg = 0;
240
241 if (mask == 0 || mask & 0xf0) {
242 pr_warning("unwind: Spare encoding %04lx\n",
243 (insn << 8) | mask);
244 return -URC_FAILURE;
245 }
246
247 /* pop R0-R3 according to mask */
248 while (mask) {
249 if (mask & 1)
250 ctrl->vrs[reg] = *vsp++;
251 mask >>= 1;
252 reg++;
253 }
254 ctrl->vrs[SP] = (unsigned long)vsp;
255 } else if (insn == 0xb2) {
256 unsigned long uleb128 = unwind_get_byte(ctrl);
257
258 ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
259 } else {
260 pr_warning("unwind: Unhandled instruction %02lx\n", insn);
261 return -URC_FAILURE;
262 }
263
264 pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
265 ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
266
267 return URC_OK;
268}
269
270/*
271 * Unwind a single frame starting with *sp for the symbol at *pc. It
272 * updates the *pc and *sp with the new values.
273 */
274int unwind_frame(struct stackframe *frame)
275{
276 unsigned long high, low;
277 struct unwind_idx *idx;
278 struct unwind_ctrl_block ctrl;
279
280 /* only go to a higher address on the stack */
281 low = frame->sp;
282 high = ALIGN(low, THREAD_SIZE);
283
284 pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
285 frame->pc, frame->lr, frame->sp);
286
287 if (!kernel_text_address(frame->pc))
288 return -URC_FAILURE;
289
290 idx = unwind_find_idx(frame->pc);
291 if (!idx) {
292 pr_warning("unwind: Index not found %08lx\n", frame->pc);
293 return -URC_FAILURE;
294 }
295
296 ctrl.vrs[FP] = frame->fp;
297 ctrl.vrs[SP] = frame->sp;
298 ctrl.vrs[LR] = frame->lr;
299 ctrl.vrs[PC] = 0;
300
301 if (idx->insn == 1)
302 /* can't unwind */
303 return -URC_FAILURE;
304 else if ((idx->insn & 0x80000000) == 0)
305 /* prel31 to the unwind table */
306 ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
307 else if ((idx->insn & 0xff000000) == 0x80000000)
308 /* only personality routine 0 supported in the index */
309 ctrl.insn = &idx->insn;
310 else {
311 pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
312 idx->insn, idx);
313 return -URC_FAILURE;
314 }
315
316 /* check the personality routine */
317 if ((*ctrl.insn & 0xff000000) == 0x80000000) {
318 ctrl.byte = 2;
319 ctrl.entries = 1;
320 } else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
321 ctrl.byte = 1;
322 ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
323 } else {
324 pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
325 *ctrl.insn, ctrl.insn);
326 return -URC_FAILURE;
327 }
328
329 while (ctrl.entries > 0) {
330 int urc = unwind_exec_insn(&ctrl);
331 if (urc < 0)
332 return urc;
333 if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
334 return -URC_FAILURE;
335 }
336
337 if (ctrl.vrs[PC] == 0)
338 ctrl.vrs[PC] = ctrl.vrs[LR];
339
340 /* check for infinite loop */
341 if (frame->pc == ctrl.vrs[PC])
342 return -URC_FAILURE;
343
344 frame->fp = ctrl.vrs[FP];
345 frame->sp = ctrl.vrs[SP];
346 frame->lr = ctrl.vrs[LR];
347 frame->pc = ctrl.vrs[PC];
348
349 return URC_OK;
350}
351
352void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
353{
354 struct stackframe frame;
355 register unsigned long current_sp asm ("sp");
356
357 pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
358
359 if (!tsk)
360 tsk = current;
361
362 if (regs) {
363 frame.fp = regs->ARM_fp;
364 frame.sp = regs->ARM_sp;
365 frame.lr = regs->ARM_lr;
366 /* PC might be corrupted, use LR in that case. */
367 frame.pc = kernel_text_address(regs->ARM_pc)
368 ? regs->ARM_pc : regs->ARM_lr;
369 } else if (tsk == current) {
370 frame.fp = (unsigned long)__builtin_frame_address(0);
371 frame.sp = current_sp;
372 frame.lr = (unsigned long)__builtin_return_address(0);
373 frame.pc = (unsigned long)unwind_backtrace;
374 } else {
375 /* task blocked in __switch_to */
376 frame.fp = thread_saved_fp(tsk);
377 frame.sp = thread_saved_sp(tsk);
378 /*
379 * The function calling __switch_to cannot be a leaf function
380 * so LR is recovered from the stack.
381 */
382 frame.lr = 0;
383 frame.pc = thread_saved_pc(tsk);
384 }
385
386 while (1) {
387 int urc;
388 unsigned long where = frame.pc;
389
390 urc = unwind_frame(&frame);
391 if (urc < 0)
392 break;
393 dump_backtrace_entry(where, frame.pc, frame.sp - 4);
394 }
395}
396
397struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
398 unsigned long text_addr,
399 unsigned long text_size)
400{
401 unsigned long flags;
402 struct unwind_idx *idx;
403 struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);
404
405 pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
406 text_addr, text_size);
407
408 if (!tab)
409 return tab;
410
411 tab->start = (struct unwind_idx *)start;
412 tab->stop = (struct unwind_idx *)(start + size);
413 tab->begin_addr = text_addr;
414 tab->end_addr = text_addr + text_size;
415
416 /* Convert the symbol addresses to absolute values */
417 for (idx = tab->start; idx < tab->stop; idx++)
418 idx->addr = prel31_to_addr(&idx->addr);
419
420 spin_lock_irqsave(&unwind_lock, flags);
421 list_add_tail(&tab->list, &unwind_tables);
422 spin_unlock_irqrestore(&unwind_lock, flags);
423
424 return tab;
425}
426
427void unwind_table_del(struct unwind_table *tab)
428{
429 unsigned long flags;
430
431 if (!tab)
432 return;
433
434 spin_lock_irqsave(&unwind_lock, flags);
435 list_del(&tab->list);
436 spin_unlock_irqrestore(&unwind_lock, flags);
437
438 kfree(tab);
439}
440
441int __init unwind_init(void)
442{
443 struct unwind_idx *idx;
444
445 /* Convert the symbol addresses to absolute values */
446 for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
447 idx->addr = prel31_to_addr(&idx->addr);
448
449 pr_debug("unwind: ARM stack unwinding initialised\n");
450
451 return 0;
452}
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}