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-rw-r--r--arch/sh/kernel/dwarf.c902
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diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
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1/*
2 * Copyright (C) 2009 Matt Fleming <matt@console-pimps.org>
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * This is an implementation of a DWARF unwinder. Its main purpose is
9 * for generating stacktrace information. Based on the DWARF 3
10 * specification from http://www.dwarfstd.org.
11 *
12 * TODO:
13 * - DWARF64 doesn't work.
14 */
15
16/* #define DEBUG */
17#include <linux/kernel.h>
18#include <linux/io.h>
19#include <linux/list.h>
20#include <linux/mm.h>
21#include <asm/dwarf.h>
22#include <asm/unwinder.h>
23#include <asm/sections.h>
24#include <asm/unaligned.h>
25#include <asm/dwarf.h>
26#include <asm/stacktrace.h>
27
28static LIST_HEAD(dwarf_cie_list);
29DEFINE_SPINLOCK(dwarf_cie_lock);
30
31static LIST_HEAD(dwarf_fde_list);
32DEFINE_SPINLOCK(dwarf_fde_lock);
33
34static struct dwarf_cie *cached_cie;
35
36/*
37 * Figure out whether we need to allocate some dwarf registers. If dwarf
38 * registers have already been allocated then we may need to realloc
39 * them. "reg" is a register number that we need to be able to access
40 * after this call.
41 *
42 * Register numbers start at zero, therefore we need to allocate space
43 * for "reg" + 1 registers.
44 */
45static void dwarf_frame_alloc_regs(struct dwarf_frame *frame,
46 unsigned int reg)
47{
48 struct dwarf_reg *regs;
49 unsigned int num_regs = reg + 1;
50 size_t new_size;
51 size_t old_size;
52
53 new_size = num_regs * sizeof(*regs);
54 old_size = frame->num_regs * sizeof(*regs);
55
56 /* Fast path: don't allocate any regs if we've already got enough. */
57 if (frame->num_regs >= num_regs)
58 return;
59
60 regs = kzalloc(new_size, GFP_ATOMIC);
61 if (!regs) {
62 printk(KERN_WARNING "Unable to allocate DWARF registers\n");
63 /*
64 * Let's just bomb hard here, we have no way to
65 * gracefully recover.
66 */
67 BUG();
68 }
69
70 if (frame->regs) {
71 memcpy(regs, frame->regs, old_size);
72 kfree(frame->regs);
73 }
74
75 frame->regs = regs;
76 frame->num_regs = num_regs;
77}
78
79/**
80 * dwarf_read_addr - read dwarf data
81 * @src: source address of data
82 * @dst: destination address to store the data to
83 *
84 * Read 'n' bytes from @src, where 'n' is the size of an address on
85 * the native machine. We return the number of bytes read, which
86 * should always be 'n'. We also have to be careful when reading
87 * from @src and writing to @dst, because they can be arbitrarily
88 * aligned. Return 'n' - the number of bytes read.
89 */
90static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst)
91{
92 u32 val = get_unaligned(src);
93 put_unaligned(val, dst);
94 return sizeof(unsigned long *);
95}
96
97/**
98 * dwarf_read_uleb128 - read unsigned LEB128 data
99 * @addr: the address where the ULEB128 data is stored
100 * @ret: address to store the result
101 *
102 * Decode an unsigned LEB128 encoded datum. The algorithm is taken
103 * from Appendix C of the DWARF 3 spec. For information on the
104 * encodings refer to section "7.6 - Variable Length Data". Return
105 * the number of bytes read.
106 */
107static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
108{
109 unsigned int result;
110 unsigned char byte;
111 int shift, count;
112
113 result = 0;
114 shift = 0;
115 count = 0;
116
117 while (1) {
118 byte = __raw_readb(addr);
119 addr++;
120 count++;
121
122 result |= (byte & 0x7f) << shift;
123 shift += 7;
124
125 if (!(byte & 0x80))
126 break;
127 }
128
129 *ret = result;
130
131 return count;
132}
133
134/**
135 * dwarf_read_leb128 - read signed LEB128 data
136 * @addr: the address of the LEB128 encoded data
137 * @ret: address to store the result
138 *
139 * Decode signed LEB128 data. The algorithm is taken from Appendix
140 * C of the DWARF 3 spec. Return the number of bytes read.
141 */
142static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
143{
144 unsigned char byte;
145 int result, shift;
146 int num_bits;
147 int count;
148
149 result = 0;
150 shift = 0;
151 count = 0;
152
153 while (1) {
154 byte = __raw_readb(addr);
155 addr++;
156 result |= (byte & 0x7f) << shift;
157 shift += 7;
158 count++;
159
160 if (!(byte & 0x80))
161 break;
162 }
163
164 /* The number of bits in a signed integer. */
165 num_bits = 8 * sizeof(result);
166
167 if ((shift < num_bits) && (byte & 0x40))
168 result |= (-1 << shift);
169
170 *ret = result;
171
172 return count;
173}
174
175/**
176 * dwarf_read_encoded_value - return the decoded value at @addr
177 * @addr: the address of the encoded value
178 * @val: where to write the decoded value
179 * @encoding: the encoding with which we can decode @addr
180 *
181 * GCC emits encoded address in the .eh_frame FDE entries. Decode
182 * the value at @addr using @encoding. The decoded value is written
183 * to @val and the number of bytes read is returned.
184 */
185static int dwarf_read_encoded_value(char *addr, unsigned long *val,
186 char encoding)
187{
188 unsigned long decoded_addr = 0;
189 int count = 0;
190
191 switch (encoding & 0x70) {
192 case DW_EH_PE_absptr:
193 break;
194 case DW_EH_PE_pcrel:
195 decoded_addr = (unsigned long)addr;
196 break;
197 default:
198 pr_debug("encoding=0x%x\n", (encoding & 0x70));
199 BUG();
200 }
201
202 if ((encoding & 0x07) == 0x00)
203 encoding |= DW_EH_PE_udata4;
204
205 switch (encoding & 0x0f) {
206 case DW_EH_PE_sdata4:
207 case DW_EH_PE_udata4:
208 count += 4;
209 decoded_addr += get_unaligned((u32 *)addr);
210 __raw_writel(decoded_addr, val);
211 break;
212 default:
213 pr_debug("encoding=0x%x\n", encoding);
214 BUG();
215 }
216
217 return count;
218}
219
220/**
221 * dwarf_entry_len - return the length of an FDE or CIE
222 * @addr: the address of the entry
223 * @len: the length of the entry
224 *
225 * Read the initial_length field of the entry and store the size of
226 * the entry in @len. We return the number of bytes read. Return a
227 * count of 0 on error.
228 */
229static inline int dwarf_entry_len(char *addr, unsigned long *len)
230{
231 u32 initial_len;
232 int count;
233
234 initial_len = get_unaligned((u32 *)addr);
235 count = 4;
236
237 /*
238 * An initial length field value in the range DW_LEN_EXT_LO -
239 * DW_LEN_EXT_HI indicates an extension, and should not be
240 * interpreted as a length. The only extension that we currently
241 * understand is the use of DWARF64 addresses.
242 */
243 if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
244 /*
245 * The 64-bit length field immediately follows the
246 * compulsory 32-bit length field.
247 */
248 if (initial_len == DW_EXT_DWARF64) {
249 *len = get_unaligned((u64 *)addr + 4);
250 count = 12;
251 } else {
252 printk(KERN_WARNING "Unknown DWARF extension\n");
253 count = 0;
254 }
255 } else
256 *len = initial_len;
257
258 return count;
259}
260
261/**
262 * dwarf_lookup_cie - locate the cie
263 * @cie_ptr: pointer to help with lookup
264 */
265static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
266{
267 struct dwarf_cie *cie, *n;
268 unsigned long flags;
269
270 spin_lock_irqsave(&dwarf_cie_lock, flags);
271
272 /*
273 * We've cached the last CIE we looked up because chances are
274 * that the FDE wants this CIE.
275 */
276 if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
277 cie = cached_cie;
278 goto out;
279 }
280
281 list_for_each_entry_safe(cie, n, &dwarf_cie_list, link) {
282 if (cie->cie_pointer == cie_ptr) {
283 cached_cie = cie;
284 break;
285 }
286 }
287
288 /* Couldn't find the entry in the list. */
289 if (&cie->link == &dwarf_cie_list)
290 cie = NULL;
291out:
292 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
293 return cie;
294}
295
296/**
297 * dwarf_lookup_fde - locate the FDE that covers pc
298 * @pc: the program counter
299 */
300struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
301{
302 unsigned long flags;
303 struct dwarf_fde *fde, *n;
304
305 spin_lock_irqsave(&dwarf_fde_lock, flags);
306 list_for_each_entry_safe(fde, n, &dwarf_fde_list, link) {
307 unsigned long start, end;
308
309 start = fde->initial_location;
310 end = fde->initial_location + fde->address_range;
311
312 if (pc >= start && pc < end)
313 break;
314 }
315
316 /* Couldn't find the entry in the list. */
317 if (&fde->link == &dwarf_fde_list)
318 fde = NULL;
319
320 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
321
322 return fde;
323}
324
325/**
326 * dwarf_cfa_execute_insns - execute instructions to calculate a CFA
327 * @insn_start: address of the first instruction
328 * @insn_end: address of the last instruction
329 * @cie: the CIE for this function
330 * @fde: the FDE for this function
331 * @frame: the instructions calculate the CFA for this frame
332 * @pc: the program counter of the address we're interested in
333 * @define_ra: keep executing insns until the return addr reg is defined?
334 *
335 * Execute the Call Frame instruction sequence starting at
336 * @insn_start and ending at @insn_end. The instructions describe
337 * how to calculate the Canonical Frame Address of a stackframe.
338 * Store the results in @frame.
339 */
340static int dwarf_cfa_execute_insns(unsigned char *insn_start,
341 unsigned char *insn_end,
342 struct dwarf_cie *cie,
343 struct dwarf_fde *fde,
344 struct dwarf_frame *frame,
345 unsigned long pc,
346 bool define_ra)
347{
348 unsigned char insn;
349 unsigned char *current_insn;
350 unsigned int count, delta, reg, expr_len, offset;
351 bool seen_ra_reg;
352
353 current_insn = insn_start;
354
355 /*
356 * If we're executing instructions for the dwarf_unwind_stack()
357 * FDE we need to keep executing instructions until the value of
358 * DWARF_ARCH_RA_REG is defined. See the comment in
359 * dwarf_unwind_stack() for more details.
360 */
361 if (define_ra)
362 seen_ra_reg = false;
363 else
364 seen_ra_reg = true;
365
366 while (current_insn < insn_end && (frame->pc <= pc || !seen_ra_reg) ) {
367 insn = __raw_readb(current_insn++);
368
369 if (!seen_ra_reg) {
370 if (frame->num_regs >= DWARF_ARCH_RA_REG &&
371 frame->regs[DWARF_ARCH_RA_REG].flags)
372 seen_ra_reg = true;
373 }
374
375 /*
376 * Firstly, handle the opcodes that embed their operands
377 * in the instructions.
378 */
379 switch (DW_CFA_opcode(insn)) {
380 case DW_CFA_advance_loc:
381 delta = DW_CFA_operand(insn);
382 delta *= cie->code_alignment_factor;
383 frame->pc += delta;
384 continue;
385 /* NOTREACHED */
386 case DW_CFA_offset:
387 reg = DW_CFA_operand(insn);
388 count = dwarf_read_uleb128(current_insn, &offset);
389 current_insn += count;
390 offset *= cie->data_alignment_factor;
391 dwarf_frame_alloc_regs(frame, reg);
392 frame->regs[reg].addr = offset;
393 frame->regs[reg].flags |= DWARF_REG_OFFSET;
394 continue;
395 /* NOTREACHED */
396 case DW_CFA_restore:
397 reg = DW_CFA_operand(insn);
398 continue;
399 /* NOTREACHED */
400 }
401
402 /*
403 * Secondly, handle the opcodes that don't embed their
404 * operands in the instruction.
405 */
406 switch (insn) {
407 case DW_CFA_nop:
408 continue;
409 case DW_CFA_advance_loc1:
410 delta = *current_insn++;
411 frame->pc += delta * cie->code_alignment_factor;
412 break;
413 case DW_CFA_advance_loc2:
414 delta = get_unaligned((u16 *)current_insn);
415 current_insn += 2;
416 frame->pc += delta * cie->code_alignment_factor;
417 break;
418 case DW_CFA_advance_loc4:
419 delta = get_unaligned((u32 *)current_insn);
420 current_insn += 4;
421 frame->pc += delta * cie->code_alignment_factor;
422 break;
423 case DW_CFA_offset_extended:
424 count = dwarf_read_uleb128(current_insn, &reg);
425 current_insn += count;
426 count = dwarf_read_uleb128(current_insn, &offset);
427 current_insn += count;
428 offset *= cie->data_alignment_factor;
429 break;
430 case DW_CFA_restore_extended:
431 count = dwarf_read_uleb128(current_insn, &reg);
432 current_insn += count;
433 break;
434 case DW_CFA_undefined:
435 count = dwarf_read_uleb128(current_insn, &reg);
436 current_insn += count;
437 break;
438 case DW_CFA_def_cfa:
439 count = dwarf_read_uleb128(current_insn,
440 &frame->cfa_register);
441 current_insn += count;
442 count = dwarf_read_uleb128(current_insn,
443 &frame->cfa_offset);
444 current_insn += count;
445
446 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
447 break;
448 case DW_CFA_def_cfa_register:
449 count = dwarf_read_uleb128(current_insn,
450 &frame->cfa_register);
451 current_insn += count;
452 frame->cfa_offset = 0;
453 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
454 break;
455 case DW_CFA_def_cfa_offset:
456 count = dwarf_read_uleb128(current_insn, &offset);
457 current_insn += count;
458 frame->cfa_offset = offset;
459 break;
460 case DW_CFA_def_cfa_expression:
461 count = dwarf_read_uleb128(current_insn, &expr_len);
462 current_insn += count;
463
464 frame->cfa_expr = current_insn;
465 frame->cfa_expr_len = expr_len;
466 current_insn += expr_len;
467
468 frame->flags |= DWARF_FRAME_CFA_REG_EXP;
469 break;
470 case DW_CFA_offset_extended_sf:
471 count = dwarf_read_uleb128(current_insn, &reg);
472 current_insn += count;
473 count = dwarf_read_leb128(current_insn, &offset);
474 current_insn += count;
475 offset *= cie->data_alignment_factor;
476 dwarf_frame_alloc_regs(frame, reg);
477 frame->regs[reg].flags |= DWARF_REG_OFFSET;
478 frame->regs[reg].addr = offset;
479 break;
480 case DW_CFA_val_offset:
481 count = dwarf_read_uleb128(current_insn, &reg);
482 current_insn += count;
483 count = dwarf_read_leb128(current_insn, &offset);
484 offset *= cie->data_alignment_factor;
485 frame->regs[reg].flags |= DWARF_REG_OFFSET;
486 frame->regs[reg].addr = offset;
487 break;
488 default:
489 pr_debug("unhandled DWARF instruction 0x%x\n", insn);
490 break;
491 }
492 }
493
494 return 0;
495}
496
497/**
498 * dwarf_unwind_stack - recursively unwind the stack
499 * @pc: address of the function to unwind
500 * @prev: struct dwarf_frame of the previous stackframe on the callstack
501 *
502 * Return a struct dwarf_frame representing the most recent frame
503 * on the callstack. Each of the lower (older) stack frames are
504 * linked via the "prev" member.
505 */
506struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
507 struct dwarf_frame *prev)
508{
509 struct dwarf_frame *frame;
510 struct dwarf_cie *cie;
511 struct dwarf_fde *fde;
512 unsigned long addr;
513 int i, offset;
514 bool define_ra = false;
515
516 /*
517 * If this is the first invocation of this recursive function we
518 * need get the contents of a physical register to get the CFA
519 * in order to begin the virtual unwinding of the stack.
520 *
521 * Setting "define_ra" to true indictates that we want
522 * dwarf_cfa_execute_insns() to continue executing instructions
523 * until we know how to calculate the value of DWARF_ARCH_RA_REG
524 * (which we need in order to kick off the whole unwinding
525 * process).
526 *
527 * NOTE: the return address is guaranteed to be setup by the
528 * time this function makes its first function call.
529 */
530 if (!pc && !prev) {
531 pc = (unsigned long)&dwarf_unwind_stack;
532 define_ra = true;
533 }
534
535 frame = kzalloc(sizeof(*frame), GFP_ATOMIC);
536 if (!frame)
537 return NULL;
538
539 frame->prev = prev;
540
541 fde = dwarf_lookup_fde(pc);
542 if (!fde) {
543 /*
544 * This is our normal exit path - the one that stops the
545 * recursion. There's two reasons why we might exit
546 * here,
547 *
548 * a) pc has no asscociated DWARF frame info and so
549 * we don't know how to unwind this frame. This is
550 * usually the case when we're trying to unwind a
551 * frame that was called from some assembly code
552 * that has no DWARF info, e.g. syscalls.
553 *
554 * b) the DEBUG info for pc is bogus. There's
555 * really no way to distinguish this case from the
556 * case above, which sucks because we could print a
557 * warning here.
558 */
559 return NULL;
560 }
561
562 cie = dwarf_lookup_cie(fde->cie_pointer);
563
564 frame->pc = fde->initial_location;
565
566 /* CIE initial instructions */
567 dwarf_cfa_execute_insns(cie->initial_instructions,
568 cie->instructions_end, cie, fde,
569 frame, pc, false);
570
571 /* FDE instructions */
572 dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
573 fde, frame, pc, define_ra);
574
575 /* Calculate the CFA */
576 switch (frame->flags) {
577 case DWARF_FRAME_CFA_REG_OFFSET:
578 if (prev) {
579 BUG_ON(!prev->regs[frame->cfa_register].flags);
580
581 addr = prev->cfa;
582 addr += prev->regs[frame->cfa_register].addr;
583 frame->cfa = __raw_readl(addr);
584
585 } else {
586 /*
587 * Again, this is the first invocation of this
588 * recurisve function. We need to physically
589 * read the contents of a register in order to
590 * get the Canonical Frame Address for this
591 * function.
592 */
593 frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
594 }
595
596 frame->cfa += frame->cfa_offset;
597 break;
598 default:
599 BUG();
600 }
601
602 /* If we haven't seen the return address reg, we're screwed. */
603 BUG_ON(!frame->regs[DWARF_ARCH_RA_REG].flags);
604
605 for (i = 0; i <= frame->num_regs; i++) {
606 struct dwarf_reg *reg = &frame->regs[i];
607
608 if (!reg->flags)
609 continue;
610
611 offset = reg->addr;
612 offset += frame->cfa;
613 }
614
615 addr = frame->cfa + frame->regs[DWARF_ARCH_RA_REG].addr;
616 frame->return_addr = __raw_readl(addr);
617
618 frame->next = dwarf_unwind_stack(frame->return_addr, frame);
619 return frame;
620}
621
622static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
623 unsigned char *end)
624{
625 struct dwarf_cie *cie;
626 unsigned long flags;
627 int count;
628
629 cie = kzalloc(sizeof(*cie), GFP_KERNEL);
630 if (!cie)
631 return -ENOMEM;
632
633 cie->length = len;
634
635 /*
636 * Record the offset into the .eh_frame section
637 * for this CIE. It allows this CIE to be
638 * quickly and easily looked up from the
639 * corresponding FDE.
640 */
641 cie->cie_pointer = (unsigned long)entry;
642
643 cie->version = *(char *)p++;
644 BUG_ON(cie->version != 1);
645
646 cie->augmentation = p;
647 p += strlen(cie->augmentation) + 1;
648
649 count = dwarf_read_uleb128(p, &cie->code_alignment_factor);
650 p += count;
651
652 count = dwarf_read_leb128(p, &cie->data_alignment_factor);
653 p += count;
654
655 /*
656 * Which column in the rule table contains the
657 * return address?
658 */
659 if (cie->version == 1) {
660 cie->return_address_reg = __raw_readb(p);
661 p++;
662 } else {
663 count = dwarf_read_uleb128(p, &cie->return_address_reg);
664 p += count;
665 }
666
667 if (cie->augmentation[0] == 'z') {
668 unsigned int length, count;
669 cie->flags |= DWARF_CIE_Z_AUGMENTATION;
670
671 count = dwarf_read_uleb128(p, &length);
672 p += count;
673
674 BUG_ON((unsigned char *)p > end);
675
676 cie->initial_instructions = p + length;
677 cie->augmentation++;
678 }
679
680 while (*cie->augmentation) {
681 /*
682 * "L" indicates a byte showing how the
683 * LSDA pointer is encoded. Skip it.
684 */
685 if (*cie->augmentation == 'L') {
686 p++;
687 cie->augmentation++;
688 } else if (*cie->augmentation == 'R') {
689 /*
690 * "R" indicates a byte showing
691 * how FDE addresses are
692 * encoded.
693 */
694 cie->encoding = *(char *)p++;
695 cie->augmentation++;
696 } else if (*cie->augmentation == 'P') {
697 /*
698 * "R" indicates a personality
699 * routine in the CIE
700 * augmentation.
701 */
702 BUG();
703 } else if (*cie->augmentation == 'S') {
704 BUG();
705 } else {
706 /*
707 * Unknown augmentation. Assume
708 * 'z' augmentation.
709 */
710 p = cie->initial_instructions;
711 BUG_ON(!p);
712 break;
713 }
714 }
715
716 cie->initial_instructions = p;
717 cie->instructions_end = end;
718
719 /* Add to list */
720 spin_lock_irqsave(&dwarf_cie_lock, flags);
721 list_add_tail(&cie->link, &dwarf_cie_list);
722 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
723
724 return 0;
725}
726
727static int dwarf_parse_fde(void *entry, u32 entry_type,
728 void *start, unsigned long len)
729{
730 struct dwarf_fde *fde;
731 struct dwarf_cie *cie;
732 unsigned long flags;
733 int count;
734 void *p = start;
735
736 fde = kzalloc(sizeof(*fde), GFP_KERNEL);
737 if (!fde)
738 return -ENOMEM;
739
740 fde->length = len;
741
742 /*
743 * In a .eh_frame section the CIE pointer is the
744 * delta between the address within the FDE
745 */
746 fde->cie_pointer = (unsigned long)(p - entry_type - 4);
747
748 cie = dwarf_lookup_cie(fde->cie_pointer);
749 fde->cie = cie;
750
751 if (cie->encoding)
752 count = dwarf_read_encoded_value(p, &fde->initial_location,
753 cie->encoding);
754 else
755 count = dwarf_read_addr(p, &fde->initial_location);
756
757 p += count;
758
759 if (cie->encoding)
760 count = dwarf_read_encoded_value(p, &fde->address_range,
761 cie->encoding & 0x0f);
762 else
763 count = dwarf_read_addr(p, &fde->address_range);
764
765 p += count;
766
767 if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) {
768 unsigned int length;
769 count = dwarf_read_uleb128(p, &length);
770 p += count + length;
771 }
772
773 /* Call frame instructions. */
774 fde->instructions = p;
775 fde->end = start + len;
776
777 /* Add to list. */
778 spin_lock_irqsave(&dwarf_fde_lock, flags);
779 list_add_tail(&fde->link, &dwarf_fde_list);
780 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
781
782 return 0;
783}
784
785static void dwarf_unwinder_dump(struct task_struct *task, struct pt_regs *regs,
786 unsigned long *sp,
787 const struct stacktrace_ops *ops, void *data)
788{
789 struct dwarf_frame *frame;
790
791 frame = dwarf_unwind_stack(0, NULL);
792
793 while (frame && frame->return_addr) {
794 ops->address(data, frame->return_addr, 1);
795 frame = frame->next;
796 }
797}
798
799static struct unwinder dwarf_unwinder = {
800 .name = "dwarf-unwinder",
801 .dump = dwarf_unwinder_dump,
802 .rating = 150,
803};
804
805static void dwarf_unwinder_cleanup(void)
806{
807 struct dwarf_cie *cie, *m;
808 struct dwarf_fde *fde, *n;
809 unsigned long flags;
810
811 /*
812 * Deallocate all the memory allocated for the DWARF unwinder.
813 * Traverse all the FDE/CIE lists and remove and free all the
814 * memory associated with those data structures.
815 */
816 spin_lock_irqsave(&dwarf_cie_lock, flags);
817 list_for_each_entry_safe(cie, m, &dwarf_cie_list, link)
818 kfree(cie);
819 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
820
821 spin_lock_irqsave(&dwarf_fde_lock, flags);
822 list_for_each_entry_safe(fde, n, &dwarf_fde_list, link)
823 kfree(fde);
824 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
825}
826
827/**
828 * dwarf_unwinder_init - initialise the dwarf unwinder
829 *
830 * Build the data structures describing the .dwarf_frame section to
831 * make it easier to lookup CIE and FDE entries. Because the
832 * .eh_frame section is packed as tightly as possible it is not
833 * easy to lookup the FDE for a given PC, so we build a list of FDE
834 * and CIE entries that make it easier.
835 */
836void dwarf_unwinder_init(void)
837{
838 u32 entry_type;
839 void *p, *entry;
840 int count, err;
841 unsigned long len;
842 unsigned int c_entries, f_entries;
843 unsigned char *end;
844 INIT_LIST_HEAD(&dwarf_cie_list);
845 INIT_LIST_HEAD(&dwarf_fde_list);
846
847 c_entries = 0;
848 f_entries = 0;
849 entry = &__start_eh_frame;
850
851 while ((char *)entry < __stop_eh_frame) {
852 p = entry;
853
854 count = dwarf_entry_len(p, &len);
855 if (count == 0) {
856 /*
857 * We read a bogus length field value. There is
858 * nothing we can do here apart from disabling
859 * the DWARF unwinder. We can't even skip this
860 * entry and move to the next one because 'len'
861 * tells us where our next entry is.
862 */
863 goto out;
864 } else
865 p += count;
866
867 /* initial length does not include itself */
868 end = p + len;
869
870 entry_type = get_unaligned((u32 *)p);
871 p += 4;
872
873 if (entry_type == DW_EH_FRAME_CIE) {
874 err = dwarf_parse_cie(entry, p, len, end);
875 if (err < 0)
876 goto out;
877 else
878 c_entries++;
879 } else {
880 err = dwarf_parse_fde(entry, entry_type, p, len);
881 if (err < 0)
882 goto out;
883 else
884 f_entries++;
885 }
886
887 entry = (char *)entry + len + 4;
888 }
889
890 printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
891 c_entries, f_entries);
892
893 err = unwinder_register(&dwarf_unwinder);
894 if (err)
895 goto out;
896
897 return;
898
899out:
900 printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
901 dwarf_unwinder_cleanup();
902}
generated by cgit v1.2.2 (git 2.25.0) at 2025-03-01 02:27:04 -0500