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-rw-r--r--arch/sh/kernel/dwarf.c876
1 files changed, 876 insertions, 0 deletions
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-generic/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_KERNEL);
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(void *src, void *dst)
91{
92 u32 val = __get_unaligned_cpu32(src);
93 __put_unaligned_cpu32(val, dst);
94
95 return sizeof(unsigned long *);
96}
97
98/**
99 * dwarf_read_uleb128 - read unsigned LEB128 data
100 * @addr: the address where the ULEB128 data is stored
101 * @ret: address to store the result
102 *
103 * Decode an unsigned LEB128 encoded datum. The algorithm is taken
104 * from Appendix C of the DWARF 3 spec. For information on the
105 * encodings refer to section "7.6 - Variable Length Data". Return
106 * the number of bytes read.
107 */
108static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
109{
110 unsigned int result;
111 unsigned char byte;
112 int shift, count;
113
114 result = 0;
115 shift = 0;
116 count = 0;
117
118 while (1) {
119 byte = __raw_readb(addr);
120 addr++;
121 count++;
122
123 result |= (byte & 0x7f) << shift;
124 shift += 7;
125
126 if (!(byte & 0x80))
127 break;
128 }
129
130 *ret = result;
131
132 return count;
133}
134
135/**
136 * dwarf_read_leb128 - read signed LEB128 data
137 * @addr: the address of the LEB128 encoded data
138 * @ret: address to store the result
139 *
140 * Decode signed LEB128 data. The algorithm is taken from Appendix
141 * C of the DWARF 3 spec. Return the number of bytes read.
142 */
143static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
144{
145 unsigned char byte;
146 int result, shift;
147 int num_bits;
148 int count;
149
150 result = 0;
151 shift = 0;
152 count = 0;
153
154 while (1) {
155 byte = __raw_readb(addr);
156 addr++;
157 result |= (byte & 0x7f) << shift;
158 shift += 7;
159 count++;
160
161 if (!(byte & 0x80))
162 break;
163 }
164
165 /* The number of bits in a signed integer. */
166 num_bits = 8 * sizeof(result);
167
168 if ((shift < num_bits) && (byte & 0x40))
169 result |= (-1 << shift);
170
171 *ret = result;
172
173 return count;
174}
175
176/**
177 * dwarf_read_encoded_value - return the decoded value at @addr
178 * @addr: the address of the encoded value
179 * @val: where to write the decoded value
180 * @encoding: the encoding with which we can decode @addr
181 *
182 * GCC emits encoded address in the .eh_frame FDE entries. Decode
183 * the value at @addr using @encoding. The decoded value is written
184 * to @val and the number of bytes read is returned.
185 */
186static int dwarf_read_encoded_value(char *addr, unsigned long *val,
187 char encoding)
188{
189 unsigned long decoded_addr = 0;
190 int count = 0;
191
192 switch (encoding & 0x70) {
193 case DW_EH_PE_absptr:
194 break;
195 case DW_EH_PE_pcrel:
196 decoded_addr = (unsigned long)addr;
197 break;
198 default:
199 pr_debug("encoding=0x%x\n", (encoding & 0x70));
200 BUG();
201 }
202
203 if ((encoding & 0x07) == 0x00)
204 encoding |= DW_EH_PE_udata4;
205
206 switch (encoding & 0x0f) {
207 case DW_EH_PE_sdata4:
208 case DW_EH_PE_udata4:
209 count += 4;
210 decoded_addr += __get_unaligned_cpu32(addr);
211 __raw_writel(decoded_addr, val);
212 break;
213 default:
214 pr_debug("encoding=0x%x\n", encoding);
215 BUG();
216 }
217
218 return count;
219}
220
221/**
222 * dwarf_entry_len - return the length of an FDE or CIE
223 * @addr: the address of the entry
224 * @len: the length of the entry
225 *
226 * Read the initial_length field of the entry and store the size of
227 * the entry in @len. We return the number of bytes read. Return a
228 * count of 0 on error.
229 */
230static inline int dwarf_entry_len(char *addr, unsigned long *len)
231{
232 u32 initial_len;
233 int count;
234
235 initial_len = __get_unaligned_cpu32(addr);
236 count = 4;
237
238 /*
239 * An initial length field value in the range DW_LEN_EXT_LO -
240 * DW_LEN_EXT_HI indicates an extension, and should not be
241 * interpreted as a length. The only extension that we currently
242 * understand is the use of DWARF64 addresses.
243 */
244 if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
245 /*
246 * The 64-bit length field immediately follows the
247 * compulsory 32-bit length field.
248 */
249 if (initial_len == DW_EXT_DWARF64) {
250 *len = __get_unaligned_cpu64(addr + 4);
251 count = 12;
252 } else {
253 printk(KERN_WARNING "Unknown DWARF extension\n");
254 count = 0;
255 }
256 } else
257 *len = initial_len;
258
259 return count;
260}
261
262/**
263 * dwarf_lookup_cie - locate the cie
264 * @cie_ptr: pointer to help with lookup
265 */
266static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
267{
268 struct dwarf_cie *cie, *n;
269 unsigned long flags;
270
271 spin_lock_irqsave(&dwarf_cie_lock, flags);
272
273 /*
274 * We've cached the last CIE we looked up because chances are
275 * that the FDE wants this CIE.
276 */
277 if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
278 cie = cached_cie;
279 goto out;
280 }
281
282 list_for_each_entry_safe(cie, n, &dwarf_cie_list, link) {
283 if (cie->cie_pointer == cie_ptr) {
284 cached_cie = cie;
285 break;
286 }
287 }
288
289 /* Couldn't find the entry in the list. */
290 if (&cie->link == &dwarf_cie_list)
291 cie = NULL;
292out:
293 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
294 return cie;
295}
296
297/**
298 * dwarf_lookup_fde - locate the FDE that covers pc
299 * @pc: the program counter
300 */
301struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
302{
303 unsigned long flags;
304 struct dwarf_fde *fde, *n;
305
306 spin_lock_irqsave(&dwarf_fde_lock, flags);
307 list_for_each_entry_safe(fde, n, &dwarf_fde_list, link) {
308 unsigned long start, end;
309
310 start = fde->initial_location;
311 end = fde->initial_location + fde->address_range;
312
313 if (pc >= start && pc < end)
314 break;
315 }
316
317 /* Couldn't find the entry in the list. */
318 if (&fde->link == &dwarf_fde_list)
319 fde = NULL;
320
321 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
322
323 return fde;
324}
325
326/**
327 * dwarf_cfa_execute_insns - execute instructions to calculate a CFA
328 * @insn_start: address of the first instruction
329 * @insn_end: address of the last instruction
330 * @cie: the CIE for this function
331 * @fde: the FDE for this function
332 * @frame: the instructions calculate the CFA for this frame
333 * @pc: the program counter of the address we're interested in
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{
347 unsigned char insn;
348 unsigned char *current_insn;
349 unsigned int count, delta, reg, expr_len, offset;
350
351 current_insn = insn_start;
352
353 while (current_insn < insn_end && frame->pc <= pc) {
354 insn = __raw_readb(current_insn++);
355
356 /*
357 * Firstly, handle the opcodes that embed their operands
358 * in the instructions.
359 */
360 switch (DW_CFA_opcode(insn)) {
361 case DW_CFA_advance_loc:
362 delta = DW_CFA_operand(insn);
363 delta *= cie->code_alignment_factor;
364 frame->pc += delta;
365 continue;
366 /* NOTREACHED */
367 case DW_CFA_offset:
368 reg = DW_CFA_operand(insn);
369 count = dwarf_read_uleb128(current_insn, &offset);
370 current_insn += count;
371 offset *= cie->data_alignment_factor;
372 dwarf_frame_alloc_regs(frame, reg);
373 frame->regs[reg].addr = offset;
374 frame->regs[reg].flags |= DWARF_REG_OFFSET;
375 continue;
376 /* NOTREACHED */
377 case DW_CFA_restore:
378 reg = DW_CFA_operand(insn);
379 continue;
380 /* NOTREACHED */
381 }
382
383 /*
384 * Secondly, handle the opcodes that don't embed their
385 * operands in the instruction.
386 */
387 switch (insn) {
388 case DW_CFA_nop:
389 continue;
390 case DW_CFA_advance_loc1:
391 delta = *current_insn++;
392 frame->pc += delta * cie->code_alignment_factor;
393 break;
394 case DW_CFA_advance_loc2:
395 delta = __get_unaligned_cpu16(current_insn);
396 current_insn += 2;
397 frame->pc += delta * cie->code_alignment_factor;
398 break;
399 case DW_CFA_advance_loc4:
400 delta = __get_unaligned_cpu32(current_insn);
401 current_insn += 4;
402 frame->pc += delta * cie->code_alignment_factor;
403 break;
404 case DW_CFA_offset_extended:
405 count = dwarf_read_uleb128(current_insn, &reg);
406 current_insn += count;
407 count = dwarf_read_uleb128(current_insn, &offset);
408 current_insn += count;
409 offset *= cie->data_alignment_factor;
410 break;
411 case DW_CFA_restore_extended:
412 count = dwarf_read_uleb128(current_insn, &reg);
413 current_insn += count;
414 break;
415 case DW_CFA_undefined:
416 count = dwarf_read_uleb128(current_insn, &reg);
417 current_insn += count;
418 break;
419 case DW_CFA_def_cfa:
420 count = dwarf_read_uleb128(current_insn,
421 &frame->cfa_register);
422 current_insn += count;
423 count = dwarf_read_uleb128(current_insn,
424 &frame->cfa_offset);
425 current_insn += count;
426
427 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
428 break;
429 case DW_CFA_def_cfa_register:
430 count = dwarf_read_uleb128(current_insn,
431 &frame->cfa_register);
432 current_insn += count;
433 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
434 break;
435 case DW_CFA_def_cfa_offset:
436 count = dwarf_read_uleb128(current_insn, &offset);
437 current_insn += count;
438 frame->cfa_offset = offset;
439 break;
440 case DW_CFA_def_cfa_expression:
441 count = dwarf_read_uleb128(current_insn, &expr_len);
442 current_insn += count;
443
444 frame->cfa_expr = current_insn;
445 frame->cfa_expr_len = expr_len;
446 current_insn += expr_len;
447
448 frame->flags |= DWARF_FRAME_CFA_REG_EXP;
449 break;
450 case DW_CFA_offset_extended_sf:
451 count = dwarf_read_uleb128(current_insn, &reg);
452 current_insn += count;
453 count = dwarf_read_leb128(current_insn, &offset);
454 current_insn += count;
455 offset *= cie->data_alignment_factor;
456 dwarf_frame_alloc_regs(frame, reg);
457 frame->regs[reg].flags |= DWARF_REG_OFFSET;
458 frame->regs[reg].addr = offset;
459 break;
460 case DW_CFA_val_offset:
461 count = dwarf_read_uleb128(current_insn, &reg);
462 current_insn += count;
463 count = dwarf_read_leb128(current_insn, &offset);
464 offset *= cie->data_alignment_factor;
465 frame->regs[reg].flags |= DWARF_REG_OFFSET;
466 frame->regs[reg].addr = offset;
467 break;
468 default:
469 pr_debug("unhandled DWARF instruction 0x%x\n", insn);
470 break;
471 }
472 }
473
474 return 0;
475}
476
477/**
478 * dwarf_unwind_stack - recursively unwind the stack
479 * @pc: address of the function to unwind
480 * @prev: struct dwarf_frame of the previous stackframe on the callstack
481 *
482 * Return a struct dwarf_frame representing the most recent frame
483 * on the callstack. Each of the lower (older) stack frames are
484 * linked via the "prev" member.
485 */
486struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
487 struct dwarf_frame *prev)
488{
489 struct dwarf_frame *frame;
490 struct dwarf_cie *cie;
491 struct dwarf_fde *fde;
492 unsigned long addr;
493 int i, offset;
494
495 /*
496 * If this is the first invocation of this recursive function we
497 * need get the contents of a physical register to get the CFA
498 * in order to begin the virtual unwinding of the stack.
499 *
500 * The constant DWARF_ARCH_UNWIND_OFFSET is added to the address of
501 * this function because the return address register
502 * (DWARF_ARCH_RA_REG) will probably not be initialised until a
503 * few instructions into the prologue.
504 */
505 if (!pc && !prev) {
506 pc = (unsigned long)&dwarf_unwind_stack;
507 pc += DWARF_ARCH_UNWIND_OFFSET;
508 }
509
510 frame = kzalloc(sizeof(*frame), GFP_KERNEL);
511 if (!frame)
512 return NULL;
513
514 frame->prev = prev;
515
516 fde = dwarf_lookup_fde(pc);
517 if (!fde) {
518 /*
519 * This is our normal exit path - the one that stops the
520 * recursion. There's two reasons why we might exit
521 * here,
522 *
523 * a) pc has no asscociated DWARF frame info and so
524 * we don't know how to unwind this frame. This is
525 * usually the case when we're trying to unwind a
526 * frame that was called from some assembly code
527 * that has no DWARF info, e.g. syscalls.
528 *
529 * b) the DEBUG info for pc is bogus. There's
530 * really no way to distinguish this case from the
531 * case above, which sucks because we could print a
532 * warning here.
533 */
534 return NULL;
535 }
536
537 cie = dwarf_lookup_cie(fde->cie_pointer);
538
539 frame->pc = fde->initial_location;
540
541 /* CIE initial instructions */
542 dwarf_cfa_execute_insns(cie->initial_instructions,
543 cie->instructions_end, cie, fde, frame, pc);
544
545 /* FDE instructions */
546 dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
547 fde, frame, pc);
548
549 /* Calculate the CFA */
550 switch (frame->flags) {
551 case DWARF_FRAME_CFA_REG_OFFSET:
552 if (prev) {
553 BUG_ON(!prev->regs[frame->cfa_register].flags);
554
555 addr = prev->cfa;
556 addr += prev->regs[frame->cfa_register].addr;
557 frame->cfa = __raw_readl(addr);
558
559 } else {
560 /*
561 * Again, this is the first invocation of this
562 * recurisve function. We need to physically
563 * read the contents of a register in order to
564 * get the Canonical Frame Address for this
565 * function.
566 */
567 frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
568 }
569
570 frame->cfa += frame->cfa_offset;
571 break;
572 default:
573 BUG();
574 }
575
576 /* If we haven't seen the return address reg, we're screwed. */
577 BUG_ON(!frame->regs[DWARF_ARCH_RA_REG].flags);
578
579 for (i = 0; i <= frame->num_regs; i++) {
580 struct dwarf_reg *reg = &frame->regs[i];
581
582 if (!reg->flags)
583 continue;
584
585 offset = reg->addr;
586 offset += frame->cfa;
587 }
588
589 addr = frame->cfa + frame->regs[DWARF_ARCH_RA_REG].addr;
590 frame->return_addr = __raw_readl(addr);
591
592 frame->next = dwarf_unwind_stack(frame->return_addr, frame);
593 return frame;
594}
595
596static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
597 unsigned char *end)
598{
599 struct dwarf_cie *cie;
600 unsigned long flags;
601 int count;
602
603 cie = kzalloc(sizeof(*cie), GFP_KERNEL);
604 if (!cie)
605 return -ENOMEM;
606
607 cie->length = len;
608
609 /*
610 * Record the offset into the .eh_frame section
611 * for this CIE. It allows this CIE to be
612 * quickly and easily looked up from the
613 * corresponding FDE.
614 */
615 cie->cie_pointer = (unsigned long)entry;
616
617 cie->version = *(char *)p++;
618 BUG_ON(cie->version != 1);
619
620 cie->augmentation = p;
621 p += strlen(cie->augmentation) + 1;
622
623 count = dwarf_read_uleb128(p, &cie->code_alignment_factor);
624 p += count;
625
626 count = dwarf_read_leb128(p, &cie->data_alignment_factor);
627 p += count;
628
629 /*
630 * Which column in the rule table contains the
631 * return address?
632 */
633 if (cie->version == 1) {
634 cie->return_address_reg = __raw_readb(p);
635 p++;
636 } else {
637 count = dwarf_read_uleb128(p, &cie->return_address_reg);
638 p += count;
639 }
640
641 if (cie->augmentation[0] == 'z') {
642 unsigned int length, count;
643 cie->flags |= DWARF_CIE_Z_AUGMENTATION;
644
645 count = dwarf_read_uleb128(p, &length);
646 p += count;
647
648 BUG_ON((unsigned char *)p > end);
649
650 cie->initial_instructions = p + length;
651 cie->augmentation++;
652 }
653
654 while (*cie->augmentation) {
655 /*
656 * "L" indicates a byte showing how the
657 * LSDA pointer is encoded. Skip it.
658 */
659 if (*cie->augmentation == 'L') {
660 p++;
661 cie->augmentation++;
662 } else if (*cie->augmentation == 'R') {
663 /*
664 * "R" indicates a byte showing
665 * how FDE addresses are
666 * encoded.
667 */
668 cie->encoding = *(char *)p++;
669 cie->augmentation++;
670 } else if (*cie->augmentation == 'P') {
671 /*
672 * "R" indicates a personality
673 * routine in the CIE
674 * augmentation.
675 */
676 BUG();
677 } else if (*cie->augmentation == 'S') {
678 BUG();
679 } else {
680 /*
681 * Unknown augmentation. Assume
682 * 'z' augmentation.
683 */
684 p = cie->initial_instructions;
685 BUG_ON(!p);
686 break;
687 }
688 }
689
690 cie->initial_instructions = p;
691 cie->instructions_end = end;
692
693 /* Add to list */
694 spin_lock_irqsave(&dwarf_cie_lock, flags);
695 list_add_tail(&cie->link, &dwarf_cie_list);
696 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
697
698 return 0;
699}
700
701static int dwarf_parse_fde(void *entry, u32 entry_type,
702 void *start, unsigned long len)
703{
704 struct dwarf_fde *fde;
705 struct dwarf_cie *cie;
706 unsigned long flags;
707 int count;
708 void *p = start;
709
710 fde = kzalloc(sizeof(*fde), GFP_KERNEL);
711 if (!fde)
712 return -ENOMEM;
713
714 fde->length = len;
715
716 /*
717 * In a .eh_frame section the CIE pointer is the
718 * delta between the address within the FDE
719 */
720 fde->cie_pointer = (unsigned long)(p - entry_type - 4);
721
722 cie = dwarf_lookup_cie(fde->cie_pointer);
723 fde->cie = cie;
724
725 if (cie->encoding)
726 count = dwarf_read_encoded_value(p, &fde->initial_location,
727 cie->encoding);
728 else
729 count = dwarf_read_addr(p, &fde->initial_location);
730
731 p += count;
732
733 if (cie->encoding)
734 count = dwarf_read_encoded_value(p, &fde->address_range,
735 cie->encoding & 0x0f);
736 else
737 count = dwarf_read_addr(p, &fde->address_range);
738
739 p += count;
740
741 if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) {
742 unsigned int length;
743 count = dwarf_read_uleb128(p, &length);
744 p += count + length;
745 }
746
747 /* Call frame instructions. */
748 fde->instructions = p;
749 fde->end = start + len;
750
751 /* Add to list. */
752 spin_lock_irqsave(&dwarf_fde_lock, flags);
753 list_add_tail(&fde->link, &dwarf_fde_list);
754 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
755
756 return 0;
757}
758
759static void dwarf_unwinder_dump(struct task_struct *task, struct pt_regs *regs,
760 unsigned long *sp,
761 const struct stacktrace_ops *ops, void *data)
762{
763 struct dwarf_frame *frame;
764
765 frame = dwarf_unwind_stack(0, NULL);
766
767 while (frame && frame->return_addr) {
768 ops->address(data, frame->return_addr, 1);
769 frame = frame->next;
770 }
771}
772
773static struct unwinder dwarf_unwinder = {
774 .name = "dwarf-unwinder",
775 .dump = dwarf_unwinder_dump,
776 .rating = 150,
777};
778
779static void dwarf_unwinder_cleanup(void)
780{
781 struct dwarf_cie *cie, *m;
782 struct dwarf_fde *fde, *n;
783 unsigned long flags;
784
785 /*
786 * Deallocate all the memory allocated for the DWARF unwinder.
787 * Traverse all the FDE/CIE lists and remove and free all the
788 * memory associated with those data structures.
789 */
790 spin_lock_irqsave(&dwarf_cie_lock, flags);
791 list_for_each_entry_safe(cie, m, &dwarf_cie_list, link)
792 kfree(cie);
793 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
794
795 spin_lock_irqsave(&dwarf_fde_lock, flags);
796 list_for_each_entry_safe(fde, n, &dwarf_fde_list, link)
797 kfree(fde);
798 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
799}
800
801/**
802 * dwarf_unwinder_init - initialise the dwarf unwinder
803 *
804 * Build the data structures describing the .dwarf_frame section to
805 * make it easier to lookup CIE and FDE entries. Because the
806 * .eh_frame section is packed as tightly as possible it is not
807 * easy to lookup the FDE for a given PC, so we build a list of FDE
808 * and CIE entries that make it easier.
809 */
810void dwarf_unwinder_init(void)
811{
812 u32 entry_type;
813 void *p, *entry;
814 int count, err;
815 unsigned long len;
816 unsigned int c_entries, f_entries;
817 unsigned char *end;
818 INIT_LIST_HEAD(&dwarf_cie_list);
819 INIT_LIST_HEAD(&dwarf_fde_list);
820
821 c_entries = 0;
822 f_entries = 0;
823 entry = &__start_eh_frame;
824
825 while ((char *)entry < __stop_eh_frame) {
826 p = entry;
827
828 count = dwarf_entry_len(p, &len);
829 if (count == 0) {
830 /*
831 * We read a bogus length field value. There is
832 * nothing we can do here apart from disabling
833 * the DWARF unwinder. We can't even skip this
834 * entry and move to the next one because 'len'
835 * tells us where our next entry is.
836 */
837 goto out;
838 } else
839 p += count;
840
841 /* initial length does not include itself */
842 end = p + len;
843
844 entry_type = __get_unaligned_cpu32(p);
845 p += 4;
846
847 if (entry_type == DW_EH_FRAME_CIE) {
848 err = dwarf_parse_cie(entry, p, len, end);
849 if (err < 0)
850 goto out;
851 else
852 c_entries++;
853 } else {
854 err = dwarf_parse_fde(entry, entry_type, p, len);
855 if (err < 0)
856 goto out;
857 else
858 f_entries++;
859 }
860
861 entry = (char *)entry + len + 4;
862 }
863
864 printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
865 c_entries, f_entries);
866
867 err = unwinder_register(&dwarf_unwinder);
868 if (err)
869 goto out;
870
871 return;
872
873out:
874 printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
875 dwarf_unwinder_cleanup();
876}
generated by cgit v1.2.2 (git 2.25.0) at 2025-02-26 22:11:32 -0500