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-rw-r--r--arch/sh/kernel/dwarf.c972
1 files changed, 972 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 * - Registers with DWARF_VAL_OFFSET rules aren't handled properly.
15 */
16
17/* #define DEBUG */
18#include <linux/kernel.h>
19#include <linux/io.h>
20#include <linux/list.h>
21#include <linux/mempool.h>
22#include <linux/mm.h>
23#include <asm/dwarf.h>
24#include <asm/unwinder.h>
25#include <asm/sections.h>
26#include <asm/unaligned.h>
27#include <asm/dwarf.h>
28#include <asm/stacktrace.h>
29
30/* Reserve enough memory for two stack frames */
31#define DWARF_FRAME_MIN_REQ 2
32/* ... with 4 registers per frame. */
33#define DWARF_REG_MIN_REQ (DWARF_FRAME_MIN_REQ * 4)
34
35static struct kmem_cache *dwarf_frame_cachep;
36static mempool_t *dwarf_frame_pool;
37
38static struct kmem_cache *dwarf_reg_cachep;
39static mempool_t *dwarf_reg_pool;
40
41static LIST_HEAD(dwarf_cie_list);
42static DEFINE_SPINLOCK(dwarf_cie_lock);
43
44static LIST_HEAD(dwarf_fde_list);
45static DEFINE_SPINLOCK(dwarf_fde_lock);
46
47static struct dwarf_cie *cached_cie;
48
49/**
50 * dwarf_frame_alloc_reg - allocate memory for a DWARF register
51 * @frame: the DWARF frame whose list of registers we insert on
52 * @reg_num: the register number
53 *
54 * Allocate space for, and initialise, a dwarf reg from
55 * dwarf_reg_pool and insert it onto the (unsorted) linked-list of
56 * dwarf registers for @frame.
57 *
58 * Return the initialised DWARF reg.
59 */
60static struct dwarf_reg *dwarf_frame_alloc_reg(struct dwarf_frame *frame,
61 unsigned int reg_num)
62{
63 struct dwarf_reg *reg;
64
65 reg = mempool_alloc(dwarf_reg_pool, GFP_ATOMIC);
66 if (!reg) {
67 printk(KERN_WARNING "Unable to allocate a DWARF register\n");
68 /*
69 * Let's just bomb hard here, we have no way to
70 * gracefully recover.
71 */
72 UNWINDER_BUG();
73 }
74
75 reg->number = reg_num;
76 reg->addr = 0;
77 reg->flags = 0;
78
79 list_add(&reg->link, &frame->reg_list);
80
81 return reg;
82}
83
84static void dwarf_frame_free_regs(struct dwarf_frame *frame)
85{
86 struct dwarf_reg *reg, *n;
87
88 list_for_each_entry_safe(reg, n, &frame->reg_list, link) {
89 list_del(&reg->link);
90 mempool_free(reg, dwarf_reg_pool);
91 }
92}
93
94/**
95 * dwarf_frame_reg - return a DWARF register
96 * @frame: the DWARF frame to search in for @reg_num
97 * @reg_num: the register number to search for
98 *
99 * Lookup and return the dwarf reg @reg_num for this frame. Return
100 * NULL if @reg_num is an register invalid number.
101 */
102static struct dwarf_reg *dwarf_frame_reg(struct dwarf_frame *frame,
103 unsigned int reg_num)
104{
105 struct dwarf_reg *reg;
106
107 list_for_each_entry(reg, &frame->reg_list, link) {
108 if (reg->number == reg_num)
109 return reg;
110 }
111
112 return NULL;
113}
114
115/**
116 * dwarf_read_addr - read dwarf data
117 * @src: source address of data
118 * @dst: destination address to store the data to
119 *
120 * Read 'n' bytes from @src, where 'n' is the size of an address on
121 * the native machine. We return the number of bytes read, which
122 * should always be 'n'. We also have to be careful when reading
123 * from @src and writing to @dst, because they can be arbitrarily
124 * aligned. Return 'n' - the number of bytes read.
125 */
126static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst)
127{
128 u32 val = get_unaligned(src);
129 put_unaligned(val, dst);
130 return sizeof(unsigned long *);
131}
132
133/**
134 * dwarf_read_uleb128 - read unsigned LEB128 data
135 * @addr: the address where the ULEB128 data is stored
136 * @ret: address to store the result
137 *
138 * Decode an unsigned LEB128 encoded datum. The algorithm is taken
139 * from Appendix C of the DWARF 3 spec. For information on the
140 * encodings refer to section "7.6 - Variable Length Data". Return
141 * the number of bytes read.
142 */
143static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
144{
145 unsigned int result;
146 unsigned char byte;
147 int shift, count;
148
149 result = 0;
150 shift = 0;
151 count = 0;
152
153 while (1) {
154 byte = __raw_readb(addr);
155 addr++;
156 count++;
157
158 result |= (byte & 0x7f) << shift;
159 shift += 7;
160
161 if (!(byte & 0x80))
162 break;
163 }
164
165 *ret = result;
166
167 return count;
168}
169
170/**
171 * dwarf_read_leb128 - read signed LEB128 data
172 * @addr: the address of the LEB128 encoded data
173 * @ret: address to store the result
174 *
175 * Decode signed LEB128 data. The algorithm is taken from Appendix
176 * C of the DWARF 3 spec. Return the number of bytes read.
177 */
178static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
179{
180 unsigned char byte;
181 int result, shift;
182 int num_bits;
183 int count;
184
185 result = 0;
186 shift = 0;
187 count = 0;
188
189 while (1) {
190 byte = __raw_readb(addr);
191 addr++;
192 result |= (byte & 0x7f) << shift;
193 shift += 7;
194 count++;
195
196 if (!(byte & 0x80))
197 break;
198 }
199
200 /* The number of bits in a signed integer. */
201 num_bits = 8 * sizeof(result);
202
203 if ((shift < num_bits) && (byte & 0x40))
204 result |= (-1 << shift);
205
206 *ret = result;
207
208 return count;
209}
210
211/**
212 * dwarf_read_encoded_value - return the decoded value at @addr
213 * @addr: the address of the encoded value
214 * @val: where to write the decoded value
215 * @encoding: the encoding with which we can decode @addr
216 *
217 * GCC emits encoded address in the .eh_frame FDE entries. Decode
218 * the value at @addr using @encoding. The decoded value is written
219 * to @val and the number of bytes read is returned.
220 */
221static int dwarf_read_encoded_value(char *addr, unsigned long *val,
222 char encoding)
223{
224 unsigned long decoded_addr = 0;
225 int count = 0;
226
227 switch (encoding & 0x70) {
228 case DW_EH_PE_absptr:
229 break;
230 case DW_EH_PE_pcrel:
231 decoded_addr = (unsigned long)addr;
232 break;
233 default:
234 pr_debug("encoding=0x%x\n", (encoding & 0x70));
235 UNWINDER_BUG();
236 }
237
238 if ((encoding & 0x07) == 0x00)
239 encoding |= DW_EH_PE_udata4;
240
241 switch (encoding & 0x0f) {
242 case DW_EH_PE_sdata4:
243 case DW_EH_PE_udata4:
244 count += 4;
245 decoded_addr += get_unaligned((u32 *)addr);
246 __raw_writel(decoded_addr, val);
247 break;
248 default:
249 pr_debug("encoding=0x%x\n", encoding);
250 UNWINDER_BUG();
251 }
252
253 return count;
254}
255
256/**
257 * dwarf_entry_len - return the length of an FDE or CIE
258 * @addr: the address of the entry
259 * @len: the length of the entry
260 *
261 * Read the initial_length field of the entry and store the size of
262 * the entry in @len. We return the number of bytes read. Return a
263 * count of 0 on error.
264 */
265static inline int dwarf_entry_len(char *addr, unsigned long *len)
266{
267 u32 initial_len;
268 int count;
269
270 initial_len = get_unaligned((u32 *)addr);
271 count = 4;
272
273 /*
274 * An initial length field value in the range DW_LEN_EXT_LO -
275 * DW_LEN_EXT_HI indicates an extension, and should not be
276 * interpreted as a length. The only extension that we currently
277 * understand is the use of DWARF64 addresses.
278 */
279 if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
280 /*
281 * The 64-bit length field immediately follows the
282 * compulsory 32-bit length field.
283 */
284 if (initial_len == DW_EXT_DWARF64) {
285 *len = get_unaligned((u64 *)addr + 4);
286 count = 12;
287 } else {
288 printk(KERN_WARNING "Unknown DWARF extension\n");
289 count = 0;
290 }
291 } else
292 *len = initial_len;
293
294 return count;
295}
296
297/**
298 * dwarf_lookup_cie - locate the cie
299 * @cie_ptr: pointer to help with lookup
300 */
301static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
302{
303 struct dwarf_cie *cie;
304 unsigned long flags;
305
306 spin_lock_irqsave(&dwarf_cie_lock, flags);
307
308 /*
309 * We've cached the last CIE we looked up because chances are
310 * that the FDE wants this CIE.
311 */
312 if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
313 cie = cached_cie;
314 goto out;
315 }
316
317 list_for_each_entry(cie, &dwarf_cie_list, link) {
318 if (cie->cie_pointer == cie_ptr) {
319 cached_cie = cie;
320 break;
321 }
322 }
323
324 /* Couldn't find the entry in the list. */
325 if (&cie->link == &dwarf_cie_list)
326 cie = NULL;
327out:
328 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
329 return cie;
330}
331
332/**
333 * dwarf_lookup_fde - locate the FDE that covers pc
334 * @pc: the program counter
335 */
336struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
337{
338 struct dwarf_fde *fde;
339 unsigned long flags;
340
341 spin_lock_irqsave(&dwarf_fde_lock, flags);
342
343 list_for_each_entry(fde, &dwarf_fde_list, link) {
344 unsigned long start, end;
345
346 start = fde->initial_location;
347 end = fde->initial_location + fde->address_range;
348
349 if (pc >= start && pc < end)
350 break;
351 }
352
353 /* Couldn't find the entry in the list. */
354 if (&fde->link == &dwarf_fde_list)
355 fde = NULL;
356
357 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
358
359 return fde;
360}
361
362/**
363 * dwarf_cfa_execute_insns - execute instructions to calculate a CFA
364 * @insn_start: address of the first instruction
365 * @insn_end: address of the last instruction
366 * @cie: the CIE for this function
367 * @fde: the FDE for this function
368 * @frame: the instructions calculate the CFA for this frame
369 * @pc: the program counter of the address we're interested in
370 *
371 * Execute the Call Frame instruction sequence starting at
372 * @insn_start and ending at @insn_end. The instructions describe
373 * how to calculate the Canonical Frame Address of a stackframe.
374 * Store the results in @frame.
375 */
376static int dwarf_cfa_execute_insns(unsigned char *insn_start,
377 unsigned char *insn_end,
378 struct dwarf_cie *cie,
379 struct dwarf_fde *fde,
380 struct dwarf_frame *frame,
381 unsigned long pc)
382{
383 unsigned char insn;
384 unsigned char *current_insn;
385 unsigned int count, delta, reg, expr_len, offset;
386 struct dwarf_reg *regp;
387
388 current_insn = insn_start;
389
390 while (current_insn < insn_end && frame->pc <= pc) {
391 insn = __raw_readb(current_insn++);
392
393 /*
394 * Firstly, handle the opcodes that embed their operands
395 * in the instructions.
396 */
397 switch (DW_CFA_opcode(insn)) {
398 case DW_CFA_advance_loc:
399 delta = DW_CFA_operand(insn);
400 delta *= cie->code_alignment_factor;
401 frame->pc += delta;
402 continue;
403 /* NOTREACHED */
404 case DW_CFA_offset:
405 reg = DW_CFA_operand(insn);
406 count = dwarf_read_uleb128(current_insn, &offset);
407 current_insn += count;
408 offset *= cie->data_alignment_factor;
409 regp = dwarf_frame_alloc_reg(frame, reg);
410 regp->addr = offset;
411 regp->flags |= DWARF_REG_OFFSET;
412 continue;
413 /* NOTREACHED */
414 case DW_CFA_restore:
415 reg = DW_CFA_operand(insn);
416 continue;
417 /* NOTREACHED */
418 }
419
420 /*
421 * Secondly, handle the opcodes that don't embed their
422 * operands in the instruction.
423 */
424 switch (insn) {
425 case DW_CFA_nop:
426 continue;
427 case DW_CFA_advance_loc1:
428 delta = *current_insn++;
429 frame->pc += delta * cie->code_alignment_factor;
430 break;
431 case DW_CFA_advance_loc2:
432 delta = get_unaligned((u16 *)current_insn);
433 current_insn += 2;
434 frame->pc += delta * cie->code_alignment_factor;
435 break;
436 case DW_CFA_advance_loc4:
437 delta = get_unaligned((u32 *)current_insn);
438 current_insn += 4;
439 frame->pc += delta * cie->code_alignment_factor;
440 break;
441 case DW_CFA_offset_extended:
442 count = dwarf_read_uleb128(current_insn, &reg);
443 current_insn += count;
444 count = dwarf_read_uleb128(current_insn, &offset);
445 current_insn += count;
446 offset *= cie->data_alignment_factor;
447 break;
448 case DW_CFA_restore_extended:
449 count = dwarf_read_uleb128(current_insn, &reg);
450 current_insn += count;
451 break;
452 case DW_CFA_undefined:
453 count = dwarf_read_uleb128(current_insn, &reg);
454 current_insn += count;
455 regp = dwarf_frame_alloc_reg(frame, reg);
456 regp->flags |= DWARF_UNDEFINED;
457 break;
458 case DW_CFA_def_cfa:
459 count = dwarf_read_uleb128(current_insn,
460 &frame->cfa_register);
461 current_insn += count;
462 count = dwarf_read_uleb128(current_insn,
463 &frame->cfa_offset);
464 current_insn += count;
465
466 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
467 break;
468 case DW_CFA_def_cfa_register:
469 count = dwarf_read_uleb128(current_insn,
470 &frame->cfa_register);
471 current_insn += count;
472 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
473 break;
474 case DW_CFA_def_cfa_offset:
475 count = dwarf_read_uleb128(current_insn, &offset);
476 current_insn += count;
477 frame->cfa_offset = offset;
478 break;
479 case DW_CFA_def_cfa_expression:
480 count = dwarf_read_uleb128(current_insn, &expr_len);
481 current_insn += count;
482
483 frame->cfa_expr = current_insn;
484 frame->cfa_expr_len = expr_len;
485 current_insn += expr_len;
486
487 frame->flags |= DWARF_FRAME_CFA_REG_EXP;
488 break;
489 case DW_CFA_offset_extended_sf:
490 count = dwarf_read_uleb128(current_insn, &reg);
491 current_insn += count;
492 count = dwarf_read_leb128(current_insn, &offset);
493 current_insn += count;
494 offset *= cie->data_alignment_factor;
495 regp = dwarf_frame_alloc_reg(frame, reg);
496 regp->flags |= DWARF_REG_OFFSET;
497 regp->addr = offset;
498 break;
499 case DW_CFA_val_offset:
500 count = dwarf_read_uleb128(current_insn, &reg);
501 current_insn += count;
502 count = dwarf_read_leb128(current_insn, &offset);
503 offset *= cie->data_alignment_factor;
504 regp = dwarf_frame_alloc_reg(frame, reg);
505 regp->flags |= DWARF_VAL_OFFSET;
506 regp->addr = offset;
507 break;
508 case DW_CFA_GNU_args_size:
509 count = dwarf_read_uleb128(current_insn, &offset);
510 current_insn += count;
511 break;
512 case DW_CFA_GNU_negative_offset_extended:
513 count = dwarf_read_uleb128(current_insn, &reg);
514 current_insn += count;
515 count = dwarf_read_uleb128(current_insn, &offset);
516 offset *= cie->data_alignment_factor;
517
518 regp = dwarf_frame_alloc_reg(frame, reg);
519 regp->flags |= DWARF_REG_OFFSET;
520 regp->addr = -offset;
521 break;
522 default:
523 pr_debug("unhandled DWARF instruction 0x%x\n", insn);
524 UNWINDER_BUG();
525 break;
526 }
527 }
528
529 return 0;
530}
531
532/**
533 * dwarf_unwind_stack - recursively unwind the stack
534 * @pc: address of the function to unwind
535 * @prev: struct dwarf_frame of the previous stackframe on the callstack
536 *
537 * Return a struct dwarf_frame representing the most recent frame
538 * on the callstack. Each of the lower (older) stack frames are
539 * linked via the "prev" member.
540 */
541struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
542 struct dwarf_frame *prev)
543{
544 struct dwarf_frame *frame;
545 struct dwarf_cie *cie;
546 struct dwarf_fde *fde;
547 struct dwarf_reg *reg;
548 unsigned long addr;
549
550 /*
551 * If this is the first invocation of this recursive function we
552 * need get the contents of a physical register to get the CFA
553 * in order to begin the virtual unwinding of the stack.
554 *
555 * NOTE: the return address is guaranteed to be setup by the
556 * time this function makes its first function call.
557 */
558 if (!pc && !prev)
559 pc = (unsigned long)current_text_addr();
560
561 frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC);
562 if (!frame) {
563 printk(KERN_ERR "Unable to allocate a dwarf frame\n");
564 UNWINDER_BUG();
565 }
566
567 INIT_LIST_HEAD(&frame->reg_list);
568 frame->flags = 0;
569 frame->prev = prev;
570 frame->return_addr = 0;
571
572 fde = dwarf_lookup_fde(pc);
573 if (!fde) {
574 /*
575 * This is our normal exit path - the one that stops the
576 * recursion. There's two reasons why we might exit
577 * here,
578 *
579 * a) pc has no asscociated DWARF frame info and so
580 * we don't know how to unwind this frame. This is
581 * usually the case when we're trying to unwind a
582 * frame that was called from some assembly code
583 * that has no DWARF info, e.g. syscalls.
584 *
585 * b) the DEBUG info for pc is bogus. There's
586 * really no way to distinguish this case from the
587 * case above, which sucks because we could print a
588 * warning here.
589 */
590 goto bail;
591 }
592
593 cie = dwarf_lookup_cie(fde->cie_pointer);
594
595 frame->pc = fde->initial_location;
596
597 /* CIE initial instructions */
598 dwarf_cfa_execute_insns(cie->initial_instructions,
599 cie->instructions_end, cie, fde,
600 frame, pc);
601
602 /* FDE instructions */
603 dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
604 fde, frame, pc);
605
606 /* Calculate the CFA */
607 switch (frame->flags) {
608 case DWARF_FRAME_CFA_REG_OFFSET:
609 if (prev) {
610 reg = dwarf_frame_reg(prev, frame->cfa_register);
611 UNWINDER_BUG_ON(!reg);
612 UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
613
614 addr = prev->cfa + reg->addr;
615 frame->cfa = __raw_readl(addr);
616
617 } else {
618 /*
619 * Again, this is the first invocation of this
620 * recurisve function. We need to physically
621 * read the contents of a register in order to
622 * get the Canonical Frame Address for this
623 * function.
624 */
625 frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
626 }
627
628 frame->cfa += frame->cfa_offset;
629 break;
630 default:
631 UNWINDER_BUG();
632 }
633
634 reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG);
635
636 /*
637 * If we haven't seen the return address register or the return
638 * address column is undefined then we must assume that this is
639 * the end of the callstack.
640 */
641 if (!reg || reg->flags == DWARF_UNDEFINED)
642 goto bail;
643
644 UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
645
646 addr = frame->cfa + reg->addr;
647 frame->return_addr = __raw_readl(addr);
648
649 return frame;
650
651bail:
652 dwarf_frame_free_regs(frame);
653 mempool_free(frame, dwarf_frame_pool);
654 return NULL;
655}
656
657static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
658 unsigned char *end)
659{
660 struct dwarf_cie *cie;
661 unsigned long flags;
662 int count;
663
664 cie = kzalloc(sizeof(*cie), GFP_KERNEL);
665 if (!cie)
666 return -ENOMEM;
667
668 cie->length = len;
669
670 /*
671 * Record the offset into the .eh_frame section
672 * for this CIE. It allows this CIE to be
673 * quickly and easily looked up from the
674 * corresponding FDE.
675 */
676 cie->cie_pointer = (unsigned long)entry;
677
678 cie->version = *(char *)p++;
679 UNWINDER_BUG_ON(cie->version != 1);
680
681 cie->augmentation = p;
682 p += strlen(cie->augmentation) + 1;
683
684 count = dwarf_read_uleb128(p, &cie->code_alignment_factor);
685 p += count;
686
687 count = dwarf_read_leb128(p, &cie->data_alignment_factor);
688 p += count;
689
690 /*
691 * Which column in the rule table contains the
692 * return address?
693 */
694 if (cie->version == 1) {
695 cie->return_address_reg = __raw_readb(p);
696 p++;
697 } else {
698 count = dwarf_read_uleb128(p, &cie->return_address_reg);
699 p += count;
700 }
701
702 if (cie->augmentation[0] == 'z') {
703 unsigned int length, count;
704 cie->flags |= DWARF_CIE_Z_AUGMENTATION;
705
706 count = dwarf_read_uleb128(p, &length);
707 p += count;
708
709 UNWINDER_BUG_ON((unsigned char *)p > end);
710
711 cie->initial_instructions = p + length;
712 cie->augmentation++;
713 }
714
715 while (*cie->augmentation) {
716 /*
717 * "L" indicates a byte showing how the
718 * LSDA pointer is encoded. Skip it.
719 */
720 if (*cie->augmentation == 'L') {
721 p++;
722 cie->augmentation++;
723 } else if (*cie->augmentation == 'R') {
724 /*
725 * "R" indicates a byte showing
726 * how FDE addresses are
727 * encoded.
728 */
729 cie->encoding = *(char *)p++;
730 cie->augmentation++;
731 } else if (*cie->augmentation == 'P') {
732 /*
733 * "R" indicates a personality
734 * routine in the CIE
735 * augmentation.
736 */
737 UNWINDER_BUG();
738 } else if (*cie->augmentation == 'S') {
739 UNWINDER_BUG();
740 } else {
741 /*
742 * Unknown augmentation. Assume
743 * 'z' augmentation.
744 */
745 p = cie->initial_instructions;
746 UNWINDER_BUG_ON(!p);
747 break;
748 }
749 }
750
751 cie->initial_instructions = p;
752 cie->instructions_end = end;
753
754 /* Add to list */
755 spin_lock_irqsave(&dwarf_cie_lock, flags);
756 list_add_tail(&cie->link, &dwarf_cie_list);
757 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
758
759 return 0;
760}
761
762static int dwarf_parse_fde(void *entry, u32 entry_type,
763 void *start, unsigned long len,
764 unsigned char *end)
765{
766 struct dwarf_fde *fde;
767 struct dwarf_cie *cie;
768 unsigned long flags;
769 int count;
770 void *p = start;
771
772 fde = kzalloc(sizeof(*fde), GFP_KERNEL);
773 if (!fde)
774 return -ENOMEM;
775
776 fde->length = len;
777
778 /*
779 * In a .eh_frame section the CIE pointer is the
780 * delta between the address within the FDE
781 */
782 fde->cie_pointer = (unsigned long)(p - entry_type - 4);
783
784 cie = dwarf_lookup_cie(fde->cie_pointer);
785 fde->cie = cie;
786
787 if (cie->encoding)
788 count = dwarf_read_encoded_value(p, &fde->initial_location,
789 cie->encoding);
790 else
791 count = dwarf_read_addr(p, &fde->initial_location);
792
793 p += count;
794
795 if (cie->encoding)
796 count = dwarf_read_encoded_value(p, &fde->address_range,
797 cie->encoding & 0x0f);
798 else
799 count = dwarf_read_addr(p, &fde->address_range);
800
801 p += count;
802
803 if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) {
804 unsigned int length;
805 count = dwarf_read_uleb128(p, &length);
806 p += count + length;
807 }
808
809 /* Call frame instructions. */
810 fde->instructions = p;
811 fde->end = end;
812
813 /* Add to list. */
814 spin_lock_irqsave(&dwarf_fde_lock, flags);
815 list_add_tail(&fde->link, &dwarf_fde_list);
816 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
817
818 return 0;
819}
820
821static void dwarf_unwinder_dump(struct task_struct *task,
822 struct pt_regs *regs,
823 unsigned long *sp,
824 const struct stacktrace_ops *ops,
825 void *data)
826{
827 struct dwarf_frame *frame, *_frame;
828 unsigned long return_addr;
829
830 _frame = NULL;
831 return_addr = 0;
832
833 while (1) {
834 frame = dwarf_unwind_stack(return_addr, _frame);
835
836 if (_frame) {
837 dwarf_frame_free_regs(_frame);
838 mempool_free(_frame, dwarf_frame_pool);
839 }
840
841 _frame = frame;
842
843 if (!frame || !frame->return_addr)
844 break;
845
846 return_addr = frame->return_addr;
847 ops->address(data, return_addr, 1);
848 }
849}
850
851static struct unwinder dwarf_unwinder = {
852 .name = "dwarf-unwinder",
853 .dump = dwarf_unwinder_dump,
854 .rating = 150,
855};
856
857static void dwarf_unwinder_cleanup(void)
858{
859 struct dwarf_cie *cie;
860 struct dwarf_fde *fde;
861
862 /*
863 * Deallocate all the memory allocated for the DWARF unwinder.
864 * Traverse all the FDE/CIE lists and remove and free all the
865 * memory associated with those data structures.
866 */
867 list_for_each_entry(cie, &dwarf_cie_list, link)
868 kfree(cie);
869
870 list_for_each_entry(fde, &dwarf_fde_list, link)
871 kfree(fde);
872
873 kmem_cache_destroy(dwarf_reg_cachep);
874 kmem_cache_destroy(dwarf_frame_cachep);
875}
876
877/**
878 * dwarf_unwinder_init - initialise the dwarf unwinder
879 *
880 * Build the data structures describing the .dwarf_frame section to
881 * make it easier to lookup CIE and FDE entries. Because the
882 * .eh_frame section is packed as tightly as possible it is not
883 * easy to lookup the FDE for a given PC, so we build a list of FDE
884 * and CIE entries that make it easier.
885 */
886static int __init dwarf_unwinder_init(void)
887{
888 u32 entry_type;
889 void *p, *entry;
890 int count, err = 0;
891 unsigned long len;
892 unsigned int c_entries, f_entries;
893 unsigned char *end;
894 INIT_LIST_HEAD(&dwarf_cie_list);
895 INIT_LIST_HEAD(&dwarf_fde_list);
896
897 c_entries = 0;
898 f_entries = 0;
899 entry = &__start_eh_frame;
900
901 dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
902 sizeof(struct dwarf_frame), 0,
903 SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
904
905 dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
906 sizeof(struct dwarf_reg), 0,
907 SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
908
909 dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
910 mempool_alloc_slab,
911 mempool_free_slab,
912 dwarf_frame_cachep);
913
914 dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
915 mempool_alloc_slab,
916 mempool_free_slab,
917 dwarf_reg_cachep);
918
919 while ((char *)entry < __stop_eh_frame) {
920 p = entry;
921
922 count = dwarf_entry_len(p, &len);
923 if (count == 0) {
924 /*
925 * We read a bogus length field value. There is
926 * nothing we can do here apart from disabling
927 * the DWARF unwinder. We can't even skip this
928 * entry and move to the next one because 'len'
929 * tells us where our next entry is.
930 */
931 goto out;
932 } else
933 p += count;
934
935 /* initial length does not include itself */
936 end = p + len;
937
938 entry_type = get_unaligned((u32 *)p);
939 p += 4;
940
941 if (entry_type == DW_EH_FRAME_CIE) {
942 err = dwarf_parse_cie(entry, p, len, end);
943 if (err < 0)
944 goto out;
945 else
946 c_entries++;
947 } else {
948 err = dwarf_parse_fde(entry, entry_type, p, len, end);
949 if (err < 0)
950 goto out;
951 else
952 f_entries++;
953 }
954
955 entry = (char *)entry + len + 4;
956 }
957
958 printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
959 c_entries, f_entries);
960
961 err = unwinder_register(&dwarf_unwinder);
962 if (err)
963 goto out;
964
965 return 0;
966
967out:
968 printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
969 dwarf_unwinder_cleanup();
970 return -EINVAL;
971}
972early_initcall(dwarf_unwinder_init);
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-25 21:21:44 -0500