]>
Commit | Line | Data |
---|---|---|
bff595c1 CM |
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 | ||
830703c7 | 29 | #ifndef __CHECKER__ |
6603a4fd CS |
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 | |
830703c7 | 38 | #endif /* __CHECKER__ */ |
6603a4fd | 39 | |
bff595c1 CM |
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 */ | |
53 | void __aeabi_unwind_cpp_pr0(void) | |
54 | { | |
55 | }; | |
56 | EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0); | |
57 | ||
58 | void __aeabi_unwind_cpp_pr1(void) | |
59 | { | |
60 | }; | |
61 | EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1); | |
62 | ||
63 | void __aeabi_unwind_cpp_pr2(void) | |
64 | { | |
65 | }; | |
66 | EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2); | |
67 | ||
68 | struct 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 | ||
75 | enum regs { | |
b86040a5 CM |
76 | #ifdef CONFIG_THUMB2_KERNEL |
77 | FP = 7, | |
78 | #else | |
bff595c1 | 79 | FP = 11, |
b86040a5 | 80 | #endif |
bff595c1 CM |
81 | SP = 13, |
82 | LR = 14, | |
83 | PC = 15 | |
84 | }; | |
85 | ||
86 | extern struct unwind_idx __start_unwind_idx[]; | |
87 | extern struct unwind_idx __stop_unwind_idx[]; | |
88 | ||
89 | static DEFINE_SPINLOCK(unwind_lock); | |
90 | static 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 | */ | |
104 | static 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 | ||
128 | static 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); | |
5333a3de PC |
149 | /* Move-to-front to exploit common traces */ |
150 | list_move(&table->list, &unwind_tables); | |
bff595c1 CM |
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 | ||
161 | static 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 | */ | |
185 | static 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) { | |
c894ed69 CM |
232 | if (ctrl->vrs[PC] == 0) |
233 | ctrl->vrs[PC] = ctrl->vrs[LR]; | |
bff595c1 CM |
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 | */ | |
274 | int 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; | |
d33aadbf | 282 | high = ALIGN(low, THREAD_SIZE); |
bff595c1 CM |
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) { | |
c894ed69 | 330 | int urc = unwind_exec_insn(&ctrl); |
bff595c1 CM |
331 | if (urc < 0) |
332 | return urc; | |
c894ed69 CM |
333 | if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high) |
334 | return -URC_FAILURE; | |
bff595c1 CM |
335 | } |
336 | ||
337 | if (ctrl.vrs[PC] == 0) | |
338 | ctrl.vrs[PC] = ctrl.vrs[LR]; | |
339 | ||
c894ed69 CM |
340 | /* check for infinite loop */ |
341 | if (frame->pc == ctrl.vrs[PC]) | |
342 | return -URC_FAILURE; | |
343 | ||
bff595c1 CM |
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 | ||
352 | void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk) | |
353 | { | |
354 | struct stackframe frame; | |
bff595c1 CM |
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; | |
51d47999 LP |
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; | |
bff595c1 CM |
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 | ||
bff595c1 CM |
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 | ||
397 | struct 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 | ||
427 | void 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 | ||
441 | int __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 | } |