2 * Copyright (C) 2009 Matt Fleming <matt@console-pimps.org>
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
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.
13 * - DWARF64 doesn't work.
14 * - Registers with DWARF_VAL_OFFSET rules aren't handled properly.
18 #include <linux/kernel.h>
20 #include <linux/list.h>
21 #include <linux/mempool.h>
23 #include <linux/elf.h>
24 #include <linux/ftrace.h>
25 #include <asm/dwarf.h>
26 #include <asm/unwinder.h>
27 #include <asm/sections.h>
28 #include <asm/unaligned.h>
29 #include <asm/stacktrace.h>
31 /* Reserve enough memory for two stack frames */
32 #define DWARF_FRAME_MIN_REQ 2
33 /* ... with 4 registers per frame. */
34 #define DWARF_REG_MIN_REQ (DWARF_FRAME_MIN_REQ * 4)
36 static struct kmem_cache *dwarf_frame_cachep;
37 static mempool_t *dwarf_frame_pool;
39 static struct kmem_cache *dwarf_reg_cachep;
40 static mempool_t *dwarf_reg_pool;
42 static LIST_HEAD(dwarf_cie_list);
43 static DEFINE_SPINLOCK(dwarf_cie_lock);
45 static LIST_HEAD(dwarf_fde_list);
46 static DEFINE_SPINLOCK(dwarf_fde_lock);
48 static struct dwarf_cie *cached_cie;
51 * dwarf_frame_alloc_reg - allocate memory for a DWARF register
52 * @frame: the DWARF frame whose list of registers we insert on
53 * @reg_num: the register number
55 * Allocate space for, and initialise, a dwarf reg from
56 * dwarf_reg_pool and insert it onto the (unsorted) linked-list of
57 * dwarf registers for @frame.
59 * Return the initialised DWARF reg.
61 static struct dwarf_reg *dwarf_frame_alloc_reg(struct dwarf_frame *frame,
64 struct dwarf_reg *reg;
66 reg = mempool_alloc(dwarf_reg_pool, GFP_ATOMIC);
68 printk(KERN_WARNING "Unable to allocate a DWARF register\n");
70 * Let's just bomb hard here, we have no way to
76 reg->number = reg_num;
80 list_add(®->link, &frame->reg_list);
85 static void dwarf_frame_free_regs(struct dwarf_frame *frame)
87 struct dwarf_reg *reg, *n;
89 list_for_each_entry_safe(reg, n, &frame->reg_list, link) {
91 mempool_free(reg, dwarf_reg_pool);
96 * dwarf_frame_reg - return a DWARF register
97 * @frame: the DWARF frame to search in for @reg_num
98 * @reg_num: the register number to search for
100 * Lookup and return the dwarf reg @reg_num for this frame. Return
101 * NULL if @reg_num is an register invalid number.
103 static struct dwarf_reg *dwarf_frame_reg(struct dwarf_frame *frame,
104 unsigned int reg_num)
106 struct dwarf_reg *reg;
108 list_for_each_entry(reg, &frame->reg_list, link) {
109 if (reg->number == reg_num)
117 * dwarf_read_addr - read dwarf data
118 * @src: source address of data
119 * @dst: destination address to store the data to
121 * Read 'n' bytes from @src, where 'n' is the size of an address on
122 * the native machine. We return the number of bytes read, which
123 * should always be 'n'. We also have to be careful when reading
124 * from @src and writing to @dst, because they can be arbitrarily
125 * aligned. Return 'n' - the number of bytes read.
127 static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst)
129 u32 val = get_unaligned(src);
130 put_unaligned(val, dst);
131 return sizeof(unsigned long *);
135 * dwarf_read_uleb128 - read unsigned LEB128 data
136 * @addr: the address where the ULEB128 data is stored
137 * @ret: address to store the result
139 * Decode an unsigned LEB128 encoded datum. The algorithm is taken
140 * from Appendix C of the DWARF 3 spec. For information on the
141 * encodings refer to section "7.6 - Variable Length Data". Return
142 * the number of bytes read.
144 static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
155 byte = __raw_readb(addr);
159 result |= (byte & 0x7f) << shift;
172 * dwarf_read_leb128 - read signed LEB128 data
173 * @addr: the address of the LEB128 encoded data
174 * @ret: address to store the result
176 * Decode signed LEB128 data. The algorithm is taken from Appendix
177 * C of the DWARF 3 spec. Return the number of bytes read.
179 static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
191 byte = __raw_readb(addr);
193 result |= (byte & 0x7f) << shift;
201 /* The number of bits in a signed integer. */
202 num_bits = 8 * sizeof(result);
204 if ((shift < num_bits) && (byte & 0x40))
205 result |= (-1 << shift);
213 * dwarf_read_encoded_value - return the decoded value at @addr
214 * @addr: the address of the encoded value
215 * @val: where to write the decoded value
216 * @encoding: the encoding with which we can decode @addr
218 * GCC emits encoded address in the .eh_frame FDE entries. Decode
219 * the value at @addr using @encoding. The decoded value is written
220 * to @val and the number of bytes read is returned.
222 static int dwarf_read_encoded_value(char *addr, unsigned long *val,
225 unsigned long decoded_addr = 0;
228 switch (encoding & 0x70) {
229 case DW_EH_PE_absptr:
232 decoded_addr = (unsigned long)addr;
235 pr_debug("encoding=0x%x\n", (encoding & 0x70));
239 if ((encoding & 0x07) == 0x00)
240 encoding |= DW_EH_PE_udata4;
242 switch (encoding & 0x0f) {
243 case DW_EH_PE_sdata4:
244 case DW_EH_PE_udata4:
246 decoded_addr += get_unaligned((u32 *)addr);
247 __raw_writel(decoded_addr, val);
250 pr_debug("encoding=0x%x\n", encoding);
258 * dwarf_entry_len - return the length of an FDE or CIE
259 * @addr: the address of the entry
260 * @len: the length of the entry
262 * Read the initial_length field of the entry and store the size of
263 * the entry in @len. We return the number of bytes read. Return a
264 * count of 0 on error.
266 static inline int dwarf_entry_len(char *addr, unsigned long *len)
271 initial_len = get_unaligned((u32 *)addr);
275 * An initial length field value in the range DW_LEN_EXT_LO -
276 * DW_LEN_EXT_HI indicates an extension, and should not be
277 * interpreted as a length. The only extension that we currently
278 * understand is the use of DWARF64 addresses.
280 if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
282 * The 64-bit length field immediately follows the
283 * compulsory 32-bit length field.
285 if (initial_len == DW_EXT_DWARF64) {
286 *len = get_unaligned((u64 *)addr + 4);
289 printk(KERN_WARNING "Unknown DWARF extension\n");
299 * dwarf_lookup_cie - locate the cie
300 * @cie_ptr: pointer to help with lookup
302 static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
304 struct dwarf_cie *cie;
307 spin_lock_irqsave(&dwarf_cie_lock, flags);
310 * We've cached the last CIE we looked up because chances are
311 * that the FDE wants this CIE.
313 if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
318 list_for_each_entry(cie, &dwarf_cie_list, link) {
319 if (cie->cie_pointer == cie_ptr) {
325 /* Couldn't find the entry in the list. */
326 if (&cie->link == &dwarf_cie_list)
329 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
334 * dwarf_lookup_fde - locate the FDE that covers pc
335 * @pc: the program counter
337 struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
339 struct dwarf_fde *fde;
342 spin_lock_irqsave(&dwarf_fde_lock, flags);
344 list_for_each_entry(fde, &dwarf_fde_list, link) {
345 unsigned long start, end;
347 start = fde->initial_location;
348 end = fde->initial_location + fde->address_range;
350 if (pc >= start && pc < end)
354 /* Couldn't find the entry in the list. */
355 if (&fde->link == &dwarf_fde_list)
358 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
364 * dwarf_cfa_execute_insns - execute instructions to calculate a CFA
365 * @insn_start: address of the first instruction
366 * @insn_end: address of the last instruction
367 * @cie: the CIE for this function
368 * @fde: the FDE for this function
369 * @frame: the instructions calculate the CFA for this frame
370 * @pc: the program counter of the address we're interested in
372 * Execute the Call Frame instruction sequence starting at
373 * @insn_start and ending at @insn_end. The instructions describe
374 * how to calculate the Canonical Frame Address of a stackframe.
375 * Store the results in @frame.
377 static int dwarf_cfa_execute_insns(unsigned char *insn_start,
378 unsigned char *insn_end,
379 struct dwarf_cie *cie,
380 struct dwarf_fde *fde,
381 struct dwarf_frame *frame,
385 unsigned char *current_insn;
386 unsigned int count, delta, reg, expr_len, offset;
387 struct dwarf_reg *regp;
389 current_insn = insn_start;
391 while (current_insn < insn_end && frame->pc <= pc) {
392 insn = __raw_readb(current_insn++);
395 * Firstly, handle the opcodes that embed their operands
396 * in the instructions.
398 switch (DW_CFA_opcode(insn)) {
399 case DW_CFA_advance_loc:
400 delta = DW_CFA_operand(insn);
401 delta *= cie->code_alignment_factor;
406 reg = DW_CFA_operand(insn);
407 count = dwarf_read_uleb128(current_insn, &offset);
408 current_insn += count;
409 offset *= cie->data_alignment_factor;
410 regp = dwarf_frame_alloc_reg(frame, reg);
412 regp->flags |= DWARF_REG_OFFSET;
416 reg = DW_CFA_operand(insn);
422 * Secondly, handle the opcodes that don't embed their
423 * operands in the instruction.
428 case DW_CFA_advance_loc1:
429 delta = *current_insn++;
430 frame->pc += delta * cie->code_alignment_factor;
432 case DW_CFA_advance_loc2:
433 delta = get_unaligned((u16 *)current_insn);
435 frame->pc += delta * cie->code_alignment_factor;
437 case DW_CFA_advance_loc4:
438 delta = get_unaligned((u32 *)current_insn);
440 frame->pc += delta * cie->code_alignment_factor;
442 case DW_CFA_offset_extended:
443 count = dwarf_read_uleb128(current_insn, ®);
444 current_insn += count;
445 count = dwarf_read_uleb128(current_insn, &offset);
446 current_insn += count;
447 offset *= cie->data_alignment_factor;
449 case DW_CFA_restore_extended:
450 count = dwarf_read_uleb128(current_insn, ®);
451 current_insn += count;
453 case DW_CFA_undefined:
454 count = dwarf_read_uleb128(current_insn, ®);
455 current_insn += count;
456 regp = dwarf_frame_alloc_reg(frame, reg);
457 regp->flags |= DWARF_UNDEFINED;
460 count = dwarf_read_uleb128(current_insn,
461 &frame->cfa_register);
462 current_insn += count;
463 count = dwarf_read_uleb128(current_insn,
465 current_insn += count;
467 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
469 case DW_CFA_def_cfa_register:
470 count = dwarf_read_uleb128(current_insn,
471 &frame->cfa_register);
472 current_insn += count;
473 frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
475 case DW_CFA_def_cfa_offset:
476 count = dwarf_read_uleb128(current_insn, &offset);
477 current_insn += count;
478 frame->cfa_offset = offset;
480 case DW_CFA_def_cfa_expression:
481 count = dwarf_read_uleb128(current_insn, &expr_len);
482 current_insn += count;
484 frame->cfa_expr = current_insn;
485 frame->cfa_expr_len = expr_len;
486 current_insn += expr_len;
488 frame->flags |= DWARF_FRAME_CFA_REG_EXP;
490 case DW_CFA_offset_extended_sf:
491 count = dwarf_read_uleb128(current_insn, ®);
492 current_insn += count;
493 count = dwarf_read_leb128(current_insn, &offset);
494 current_insn += count;
495 offset *= cie->data_alignment_factor;
496 regp = dwarf_frame_alloc_reg(frame, reg);
497 regp->flags |= DWARF_REG_OFFSET;
500 case DW_CFA_val_offset:
501 count = dwarf_read_uleb128(current_insn, ®);
502 current_insn += count;
503 count = dwarf_read_leb128(current_insn, &offset);
504 offset *= cie->data_alignment_factor;
505 regp = dwarf_frame_alloc_reg(frame, reg);
506 regp->flags |= DWARF_VAL_OFFSET;
509 case DW_CFA_GNU_args_size:
510 count = dwarf_read_uleb128(current_insn, &offset);
511 current_insn += count;
513 case DW_CFA_GNU_negative_offset_extended:
514 count = dwarf_read_uleb128(current_insn, ®);
515 current_insn += count;
516 count = dwarf_read_uleb128(current_insn, &offset);
517 offset *= cie->data_alignment_factor;
519 regp = dwarf_frame_alloc_reg(frame, reg);
520 regp->flags |= DWARF_REG_OFFSET;
521 regp->addr = -offset;
524 pr_debug("unhandled DWARF instruction 0x%x\n", insn);
534 * dwarf_free_frame - free the memory allocated for @frame
535 * @frame: the frame to free
537 void dwarf_free_frame(struct dwarf_frame *frame)
539 dwarf_frame_free_regs(frame);
540 mempool_free(frame, dwarf_frame_pool);
543 extern void ret_from_irq(void);
546 * dwarf_unwind_stack - unwind the stack
548 * @pc: address of the function to unwind
549 * @prev: struct dwarf_frame of the previous stackframe on the callstack
551 * Return a struct dwarf_frame representing the most recent frame
552 * on the callstack. Each of the lower (older) stack frames are
553 * linked via the "prev" member.
555 struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
556 struct dwarf_frame *prev)
558 struct dwarf_frame *frame;
559 struct dwarf_cie *cie;
560 struct dwarf_fde *fde;
561 struct dwarf_reg *reg;
565 * If we're starting at the top of the stack we need get the
566 * contents of a physical register to get the CFA in order to
567 * begin the virtual unwinding of the stack.
569 * NOTE: the return address is guaranteed to be setup by the
570 * time this function makes its first function call.
573 pc = (unsigned long)current_text_addr();
575 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
577 * If our stack has been patched by the function graph tracer
578 * then we might see the address of return_to_handler() where we
579 * expected to find the real return address.
581 if (pc == (unsigned long)&return_to_handler) {
582 int index = current->curr_ret_stack;
585 * We currently have no way of tracking how many
586 * return_to_handler()'s we've seen. If there is more
587 * than one patched return address on our stack,
592 pc = current->ret_stack[index].ret;
596 frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC);
598 printk(KERN_ERR "Unable to allocate a dwarf frame\n");
602 INIT_LIST_HEAD(&frame->reg_list);
605 frame->return_addr = 0;
607 fde = dwarf_lookup_fde(pc);
610 * This is our normal exit path. There are two reasons
611 * why we might exit here,
613 * a) pc has no asscociated DWARF frame info and so
614 * we don't know how to unwind this frame. This is
615 * usually the case when we're trying to unwind a
616 * frame that was called from some assembly code
617 * that has no DWARF info, e.g. syscalls.
619 * b) the DEBUG info for pc is bogus. There's
620 * really no way to distinguish this case from the
621 * case above, which sucks because we could print a
627 cie = dwarf_lookup_cie(fde->cie_pointer);
629 frame->pc = fde->initial_location;
631 /* CIE initial instructions */
632 dwarf_cfa_execute_insns(cie->initial_instructions,
633 cie->instructions_end, cie, fde,
636 /* FDE instructions */
637 dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
640 /* Calculate the CFA */
641 switch (frame->flags) {
642 case DWARF_FRAME_CFA_REG_OFFSET:
644 reg = dwarf_frame_reg(prev, frame->cfa_register);
645 UNWINDER_BUG_ON(!reg);
646 UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
648 addr = prev->cfa + reg->addr;
649 frame->cfa = __raw_readl(addr);
653 * Again, we're starting from the top of the
654 * stack. We need to physically read
655 * the contents of a register in order to get
656 * the Canonical Frame Address for this
659 frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
662 frame->cfa += frame->cfa_offset;
668 reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG);
671 * If we haven't seen the return address register or the return
672 * address column is undefined then we must assume that this is
673 * the end of the callstack.
675 if (!reg || reg->flags == DWARF_UNDEFINED)
678 UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
680 addr = frame->cfa + reg->addr;
681 frame->return_addr = __raw_readl(addr);
684 * Ah, the joys of unwinding through interrupts.
686 * Interrupts are tricky - the DWARF info needs to be _really_
687 * accurate and unfortunately I'm seeing a lot of bogus DWARF
688 * info. For example, I've seen interrupts occur in epilogues
689 * just after the frame pointer (r14) had been restored. The
690 * problem was that the DWARF info claimed that the CFA could be
691 * reached by using the value of the frame pointer before it was
694 * So until the compiler can be trusted to produce reliable
695 * DWARF info when it really matters, let's stop unwinding once
696 * we've calculated the function that was interrupted.
698 if (prev && prev->pc == (unsigned long)ret_from_irq)
699 frame->return_addr = 0;
704 dwarf_free_frame(frame);
708 static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
709 unsigned char *end, struct module *mod)
711 struct dwarf_cie *cie;
715 cie = kzalloc(sizeof(*cie), GFP_KERNEL);
722 * Record the offset into the .eh_frame section
723 * for this CIE. It allows this CIE to be
724 * quickly and easily looked up from the
727 cie->cie_pointer = (unsigned long)entry;
729 cie->version = *(char *)p++;
730 UNWINDER_BUG_ON(cie->version != 1);
732 cie->augmentation = p;
733 p += strlen(cie->augmentation) + 1;
735 count = dwarf_read_uleb128(p, &cie->code_alignment_factor);
738 count = dwarf_read_leb128(p, &cie->data_alignment_factor);
742 * Which column in the rule table contains the
745 if (cie->version == 1) {
746 cie->return_address_reg = __raw_readb(p);
749 count = dwarf_read_uleb128(p, &cie->return_address_reg);
753 if (cie->augmentation[0] == 'z') {
754 unsigned int length, count;
755 cie->flags |= DWARF_CIE_Z_AUGMENTATION;
757 count = dwarf_read_uleb128(p, &length);
760 UNWINDER_BUG_ON((unsigned char *)p > end);
762 cie->initial_instructions = p + length;
766 while (*cie->augmentation) {
768 * "L" indicates a byte showing how the
769 * LSDA pointer is encoded. Skip it.
771 if (*cie->augmentation == 'L') {
774 } else if (*cie->augmentation == 'R') {
776 * "R" indicates a byte showing
777 * how FDE addresses are
780 cie->encoding = *(char *)p++;
782 } else if (*cie->augmentation == 'P') {
784 * "R" indicates a personality
789 } else if (*cie->augmentation == 'S') {
793 * Unknown augmentation. Assume
796 p = cie->initial_instructions;
802 cie->initial_instructions = p;
803 cie->instructions_end = end;
808 spin_lock_irqsave(&dwarf_cie_lock, flags);
809 list_add_tail(&cie->link, &dwarf_cie_list);
810 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
815 static int dwarf_parse_fde(void *entry, u32 entry_type,
816 void *start, unsigned long len,
817 unsigned char *end, struct module *mod)
819 struct dwarf_fde *fde;
820 struct dwarf_cie *cie;
825 fde = kzalloc(sizeof(*fde), GFP_KERNEL);
832 * In a .eh_frame section the CIE pointer is the
833 * delta between the address within the FDE
835 fde->cie_pointer = (unsigned long)(p - entry_type - 4);
837 cie = dwarf_lookup_cie(fde->cie_pointer);
841 count = dwarf_read_encoded_value(p, &fde->initial_location,
844 count = dwarf_read_addr(p, &fde->initial_location);
849 count = dwarf_read_encoded_value(p, &fde->address_range,
850 cie->encoding & 0x0f);
852 count = dwarf_read_addr(p, &fde->address_range);
856 if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) {
858 count = dwarf_read_uleb128(p, &length);
862 /* Call frame instructions. */
863 fde->instructions = p;
869 spin_lock_irqsave(&dwarf_fde_lock, flags);
870 list_add_tail(&fde->link, &dwarf_fde_list);
871 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
876 static void dwarf_unwinder_dump(struct task_struct *task,
877 struct pt_regs *regs,
879 const struct stacktrace_ops *ops,
882 struct dwarf_frame *frame, *_frame;
883 unsigned long return_addr;
889 frame = dwarf_unwind_stack(return_addr, _frame);
892 dwarf_free_frame(_frame);
896 if (!frame || !frame->return_addr)
899 return_addr = frame->return_addr;
900 ops->address(data, return_addr, 1);
904 dwarf_free_frame(frame);
907 static struct unwinder dwarf_unwinder = {
908 .name = "dwarf-unwinder",
909 .dump = dwarf_unwinder_dump,
913 static void dwarf_unwinder_cleanup(void)
915 struct dwarf_cie *cie, *cie_tmp;
916 struct dwarf_fde *fde, *fde_tmp;
919 * Deallocate all the memory allocated for the DWARF unwinder.
920 * Traverse all the FDE/CIE lists and remove and free all the
921 * memory associated with those data structures.
923 list_for_each_entry_safe(cie, cie_tmp, &dwarf_cie_list, link)
926 list_for_each_entry_safe(fde, fde_tmp, &dwarf_fde_list, link)
929 kmem_cache_destroy(dwarf_reg_cachep);
930 kmem_cache_destroy(dwarf_frame_cachep);
934 * dwarf_parse_section - parse DWARF section
935 * @eh_frame_start: start address of the .eh_frame section
936 * @eh_frame_end: end address of the .eh_frame section
937 * @mod: the kernel module containing the .eh_frame section
939 * Parse the information in a .eh_frame section.
941 static int dwarf_parse_section(char *eh_frame_start, char *eh_frame_end,
947 unsigned long len = 0;
948 unsigned int c_entries, f_entries;
953 entry = eh_frame_start;
955 while ((char *)entry < eh_frame_end) {
958 count = dwarf_entry_len(p, &len);
961 * We read a bogus length field value. There is
962 * nothing we can do here apart from disabling
963 * the DWARF unwinder. We can't even skip this
964 * entry and move to the next one because 'len'
965 * tells us where our next entry is.
972 /* initial length does not include itself */
975 entry_type = get_unaligned((u32 *)p);
978 if (entry_type == DW_EH_FRAME_CIE) {
979 err = dwarf_parse_cie(entry, p, len, end, mod);
985 err = dwarf_parse_fde(entry, entry_type, p, len,
993 entry = (char *)entry + len + 4;
996 printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
997 c_entries, f_entries);
1005 #ifdef CONFIG_MODULES
1006 int module_dwarf_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
1009 unsigned int i, err;
1010 unsigned long start, end;
1011 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
1015 for (i = 1; i < hdr->e_shnum; i++) {
1016 /* Alloc bit cleared means "ignore it." */
1017 if ((sechdrs[i].sh_flags & SHF_ALLOC)
1018 && !strcmp(secstrings+sechdrs[i].sh_name, ".eh_frame")) {
1019 start = sechdrs[i].sh_addr;
1020 end = start + sechdrs[i].sh_size;
1025 /* Did we find the .eh_frame section? */
1026 if (i != hdr->e_shnum) {
1027 err = dwarf_parse_section((char *)start, (char *)end, me);
1029 printk(KERN_WARNING "%s: failed to parse DWARF info\n",
1039 * module_dwarf_cleanup - remove FDE/CIEs associated with @mod
1040 * @mod: the module that is being unloaded
1042 * Remove any FDEs and CIEs from the global lists that came from
1043 * @mod's .eh_frame section because @mod is being unloaded.
1045 void module_dwarf_cleanup(struct module *mod)
1047 struct dwarf_fde *fde;
1048 struct dwarf_cie *cie;
1049 unsigned long flags;
1051 spin_lock_irqsave(&dwarf_cie_lock, flags);
1054 list_for_each_entry(cie, &dwarf_cie_list, link) {
1055 if (cie->mod == mod)
1059 if (&cie->link != &dwarf_cie_list) {
1060 list_del(&cie->link);
1065 spin_unlock_irqrestore(&dwarf_cie_lock, flags);
1067 spin_lock_irqsave(&dwarf_fde_lock, flags);
1070 list_for_each_entry(fde, &dwarf_fde_list, link) {
1071 if (fde->mod == mod)
1075 if (&fde->link != &dwarf_fde_list) {
1076 list_del(&fde->link);
1081 spin_unlock_irqrestore(&dwarf_fde_lock, flags);
1083 #endif /* CONFIG_MODULES */
1086 * dwarf_unwinder_init - initialise the dwarf unwinder
1088 * Build the data structures describing the .dwarf_frame section to
1089 * make it easier to lookup CIE and FDE entries. Because the
1090 * .eh_frame section is packed as tightly as possible it is not
1091 * easy to lookup the FDE for a given PC, so we build a list of FDE
1092 * and CIE entries that make it easier.
1094 static int __init dwarf_unwinder_init(void)
1097 INIT_LIST_HEAD(&dwarf_cie_list);
1098 INIT_LIST_HEAD(&dwarf_fde_list);
1100 dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
1101 sizeof(struct dwarf_frame), 0,
1102 SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
1104 dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
1105 sizeof(struct dwarf_reg), 0,
1106 SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
1108 dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
1111 dwarf_frame_cachep);
1113 dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
1118 err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);
1122 err = unwinder_register(&dwarf_unwinder);
1129 printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
1130 dwarf_unwinder_cleanup();
1133 early_initcall(dwarf_unwinder_init);