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1206 lines
29 KiB
1206 lines
29 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2009 Matt Fleming <[email protected]> |
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* |
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* This is an implementation of a DWARF unwinder. Its main purpose is |
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* for generating stacktrace information. Based on the DWARF 3 |
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* specification from http://www.dwarfstd.org. |
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* |
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* TODO: |
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* - DWARF64 doesn't work. |
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* - Registers with DWARF_VAL_OFFSET rules aren't handled properly. |
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*/ |
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|
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/* #define DEBUG */ |
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#include <linux/kernel.h> |
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#include <linux/io.h> |
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#include <linux/list.h> |
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#include <linux/mempool.h> |
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#include <linux/mm.h> |
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#include <linux/elf.h> |
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#include <linux/ftrace.h> |
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#include <linux/module.h> |
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#include <linux/slab.h> |
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#include <asm/dwarf.h> |
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#include <asm/unwinder.h> |
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#include <asm/sections.h> |
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#include <asm/unaligned.h> |
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#include <asm/stacktrace.h> |
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|
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/* Reserve enough memory for two stack frames */ |
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#define DWARF_FRAME_MIN_REQ 2 |
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/* ... with 4 registers per frame. */ |
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#define DWARF_REG_MIN_REQ (DWARF_FRAME_MIN_REQ * 4) |
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|
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static struct kmem_cache *dwarf_frame_cachep; |
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static mempool_t *dwarf_frame_pool; |
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|
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static struct kmem_cache *dwarf_reg_cachep; |
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static mempool_t *dwarf_reg_pool; |
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|
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static struct rb_root cie_root; |
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static DEFINE_SPINLOCK(dwarf_cie_lock); |
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|
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static struct rb_root fde_root; |
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static DEFINE_SPINLOCK(dwarf_fde_lock); |
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|
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static struct dwarf_cie *cached_cie; |
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|
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static unsigned int dwarf_unwinder_ready; |
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|
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/** |
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* dwarf_frame_alloc_reg - allocate memory for a DWARF register |
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* @frame: the DWARF frame whose list of registers we insert on |
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* @reg_num: the register number |
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* |
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* Allocate space for, and initialise, a dwarf reg from |
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* dwarf_reg_pool and insert it onto the (unsorted) linked-list of |
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* dwarf registers for @frame. |
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* |
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* Return the initialised DWARF reg. |
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*/ |
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static struct dwarf_reg *dwarf_frame_alloc_reg(struct dwarf_frame *frame, |
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unsigned int reg_num) |
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{ |
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struct dwarf_reg *reg; |
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|
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reg = mempool_alloc(dwarf_reg_pool, GFP_ATOMIC); |
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if (!reg) { |
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printk(KERN_WARNING "Unable to allocate a DWARF register\n"); |
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/* |
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* Let's just bomb hard here, we have no way to |
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* gracefully recover. |
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*/ |
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UNWINDER_BUG(); |
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} |
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|
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reg->number = reg_num; |
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reg->addr = 0; |
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reg->flags = 0; |
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|
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list_add(®->link, &frame->reg_list); |
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|
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return reg; |
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} |
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|
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static void dwarf_frame_free_regs(struct dwarf_frame *frame) |
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{ |
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struct dwarf_reg *reg, *n; |
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|
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list_for_each_entry_safe(reg, n, &frame->reg_list, link) { |
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list_del(®->link); |
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mempool_free(reg, dwarf_reg_pool); |
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} |
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} |
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|
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/** |
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* dwarf_frame_reg - return a DWARF register |
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* @frame: the DWARF frame to search in for @reg_num |
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* @reg_num: the register number to search for |
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* |
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* Lookup and return the dwarf reg @reg_num for this frame. Return |
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* NULL if @reg_num is an register invalid number. |
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*/ |
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static struct dwarf_reg *dwarf_frame_reg(struct dwarf_frame *frame, |
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unsigned int reg_num) |
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{ |
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struct dwarf_reg *reg; |
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|
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list_for_each_entry(reg, &frame->reg_list, link) { |
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if (reg->number == reg_num) |
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return reg; |
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} |
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|
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return NULL; |
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} |
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|
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/** |
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* dwarf_read_addr - read dwarf data |
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* @src: source address of data |
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* @dst: destination address to store the data to |
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* |
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* Read 'n' bytes from @src, where 'n' is the size of an address on |
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* the native machine. We return the number of bytes read, which |
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* should always be 'n'. We also have to be careful when reading |
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* from @src and writing to @dst, because they can be arbitrarily |
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* aligned. Return 'n' - the number of bytes read. |
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*/ |
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static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst) |
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{ |
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u32 val = get_unaligned(src); |
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put_unaligned(val, dst); |
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return sizeof(unsigned long *); |
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} |
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|
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/** |
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* dwarf_read_uleb128 - read unsigned LEB128 data |
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* @addr: the address where the ULEB128 data is stored |
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* @ret: address to store the result |
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* |
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* Decode an unsigned LEB128 encoded datum. The algorithm is taken |
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* from Appendix C of the DWARF 3 spec. For information on the |
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* encodings refer to section "7.6 - Variable Length Data". Return |
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* the number of bytes read. |
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*/ |
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static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret) |
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{ |
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unsigned int result; |
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unsigned char byte; |
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int shift, count; |
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|
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result = 0; |
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shift = 0; |
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count = 0; |
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|
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while (1) { |
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byte = __raw_readb(addr); |
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addr++; |
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count++; |
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result |= (byte & 0x7f) << shift; |
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shift += 7; |
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|
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if (!(byte & 0x80)) |
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break; |
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} |
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|
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*ret = result; |
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|
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return count; |
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} |
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|
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/** |
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* dwarf_read_leb128 - read signed LEB128 data |
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* @addr: the address of the LEB128 encoded data |
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* @ret: address to store the result |
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* |
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* Decode signed LEB128 data. The algorithm is taken from Appendix |
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* C of the DWARF 3 spec. Return the number of bytes read. |
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*/ |
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static inline unsigned long dwarf_read_leb128(char *addr, int *ret) |
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{ |
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unsigned char byte; |
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int result, shift; |
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int num_bits; |
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int count; |
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|
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result = 0; |
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shift = 0; |
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count = 0; |
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|
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while (1) { |
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byte = __raw_readb(addr); |
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addr++; |
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result |= (byte & 0x7f) << shift; |
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shift += 7; |
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count++; |
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|
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if (!(byte & 0x80)) |
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break; |
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} |
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|
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/* The number of bits in a signed integer. */ |
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num_bits = 8 * sizeof(result); |
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|
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if ((shift < num_bits) && (byte & 0x40)) |
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result |= (-1 << shift); |
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|
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*ret = result; |
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|
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return count; |
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} |
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|
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/** |
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* dwarf_read_encoded_value - return the decoded value at @addr |
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* @addr: the address of the encoded value |
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* @val: where to write the decoded value |
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* @encoding: the encoding with which we can decode @addr |
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* |
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* GCC emits encoded address in the .eh_frame FDE entries. Decode |
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* the value at @addr using @encoding. The decoded value is written |
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* to @val and the number of bytes read is returned. |
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*/ |
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static int dwarf_read_encoded_value(char *addr, unsigned long *val, |
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char encoding) |
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{ |
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unsigned long decoded_addr = 0; |
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int count = 0; |
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|
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switch (encoding & 0x70) { |
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case DW_EH_PE_absptr: |
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break; |
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case DW_EH_PE_pcrel: |
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decoded_addr = (unsigned long)addr; |
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break; |
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default: |
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pr_debug("encoding=0x%x\n", (encoding & 0x70)); |
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UNWINDER_BUG(); |
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} |
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|
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if ((encoding & 0x07) == 0x00) |
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encoding |= DW_EH_PE_udata4; |
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|
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switch (encoding & 0x0f) { |
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case DW_EH_PE_sdata4: |
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case DW_EH_PE_udata4: |
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count += 4; |
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decoded_addr += get_unaligned((u32 *)addr); |
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__raw_writel(decoded_addr, val); |
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break; |
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default: |
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pr_debug("encoding=0x%x\n", encoding); |
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UNWINDER_BUG(); |
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} |
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|
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return count; |
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} |
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|
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/** |
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* dwarf_entry_len - return the length of an FDE or CIE |
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* @addr: the address of the entry |
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* @len: the length of the entry |
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* |
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* Read the initial_length field of the entry and store the size of |
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* the entry in @len. We return the number of bytes read. Return a |
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* count of 0 on error. |
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*/ |
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static inline int dwarf_entry_len(char *addr, unsigned long *len) |
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{ |
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u32 initial_len; |
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int count; |
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|
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initial_len = get_unaligned((u32 *)addr); |
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count = 4; |
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|
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/* |
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* An initial length field value in the range DW_LEN_EXT_LO - |
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* DW_LEN_EXT_HI indicates an extension, and should not be |
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* interpreted as a length. The only extension that we currently |
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* understand is the use of DWARF64 addresses. |
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*/ |
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if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) { |
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/* |
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* The 64-bit length field immediately follows the |
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* compulsory 32-bit length field. |
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*/ |
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if (initial_len == DW_EXT_DWARF64) { |
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*len = get_unaligned((u64 *)addr + 4); |
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count = 12; |
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} else { |
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printk(KERN_WARNING "Unknown DWARF extension\n"); |
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count = 0; |
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} |
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} else |
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*len = initial_len; |
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return count; |
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} |
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|
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/** |
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* dwarf_lookup_cie - locate the cie |
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* @cie_ptr: pointer to help with lookup |
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*/ |
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static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr) |
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{ |
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struct rb_node **rb_node = &cie_root.rb_node; |
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struct dwarf_cie *cie = NULL; |
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unsigned long flags; |
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|
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spin_lock_irqsave(&dwarf_cie_lock, flags); |
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|
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/* |
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* We've cached the last CIE we looked up because chances are |
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* that the FDE wants this CIE. |
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*/ |
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if (cached_cie && cached_cie->cie_pointer == cie_ptr) { |
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cie = cached_cie; |
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goto out; |
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} |
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while (*rb_node) { |
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struct dwarf_cie *cie_tmp; |
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cie_tmp = rb_entry(*rb_node, struct dwarf_cie, node); |
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BUG_ON(!cie_tmp); |
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if (cie_ptr == cie_tmp->cie_pointer) { |
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cie = cie_tmp; |
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cached_cie = cie_tmp; |
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goto out; |
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} else { |
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if (cie_ptr < cie_tmp->cie_pointer) |
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rb_node = &(*rb_node)->rb_left; |
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else |
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rb_node = &(*rb_node)->rb_right; |
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} |
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} |
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out: |
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spin_unlock_irqrestore(&dwarf_cie_lock, flags); |
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return cie; |
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} |
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/** |
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* dwarf_lookup_fde - locate the FDE that covers pc |
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* @pc: the program counter |
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*/ |
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struct dwarf_fde *dwarf_lookup_fde(unsigned long pc) |
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{ |
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struct rb_node **rb_node = &fde_root.rb_node; |
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struct dwarf_fde *fde = NULL; |
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unsigned long flags; |
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spin_lock_irqsave(&dwarf_fde_lock, flags); |
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while (*rb_node) { |
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struct dwarf_fde *fde_tmp; |
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unsigned long tmp_start, tmp_end; |
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fde_tmp = rb_entry(*rb_node, struct dwarf_fde, node); |
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BUG_ON(!fde_tmp); |
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tmp_start = fde_tmp->initial_location; |
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tmp_end = fde_tmp->initial_location + fde_tmp->address_range; |
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if (pc < tmp_start) { |
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rb_node = &(*rb_node)->rb_left; |
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} else { |
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if (pc < tmp_end) { |
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fde = fde_tmp; |
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goto out; |
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} else |
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rb_node = &(*rb_node)->rb_right; |
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} |
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} |
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out: |
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spin_unlock_irqrestore(&dwarf_fde_lock, flags); |
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return fde; |
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} |
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|
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/** |
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* dwarf_cfa_execute_insns - execute instructions to calculate a CFA |
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* @insn_start: address of the first instruction |
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* @insn_end: address of the last instruction |
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* @cie: the CIE for this function |
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* @fde: the FDE for this function |
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* @frame: the instructions calculate the CFA for this frame |
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* @pc: the program counter of the address we're interested in |
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* |
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* Execute the Call Frame instruction sequence starting at |
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* @insn_start and ending at @insn_end. The instructions describe |
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* how to calculate the Canonical Frame Address of a stackframe. |
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* Store the results in @frame. |
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*/ |
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static int dwarf_cfa_execute_insns(unsigned char *insn_start, |
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unsigned char *insn_end, |
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struct dwarf_cie *cie, |
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struct dwarf_fde *fde, |
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struct dwarf_frame *frame, |
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unsigned long pc) |
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{ |
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unsigned char insn; |
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unsigned char *current_insn; |
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unsigned int count, delta, reg, expr_len, offset; |
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struct dwarf_reg *regp; |
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current_insn = insn_start; |
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|
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while (current_insn < insn_end && frame->pc <= pc) { |
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insn = __raw_readb(current_insn++); |
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|
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/* |
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* Firstly, handle the opcodes that embed their operands |
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* in the instructions. |
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*/ |
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switch (DW_CFA_opcode(insn)) { |
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case DW_CFA_advance_loc: |
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delta = DW_CFA_operand(insn); |
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delta *= cie->code_alignment_factor; |
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frame->pc += delta; |
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continue; |
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/* NOTREACHED */ |
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case DW_CFA_offset: |
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reg = DW_CFA_operand(insn); |
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count = dwarf_read_uleb128(current_insn, &offset); |
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current_insn += count; |
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offset *= cie->data_alignment_factor; |
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regp = dwarf_frame_alloc_reg(frame, reg); |
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regp->addr = offset; |
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regp->flags |= DWARF_REG_OFFSET; |
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continue; |
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/* NOTREACHED */ |
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case DW_CFA_restore: |
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reg = DW_CFA_operand(insn); |
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continue; |
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/* NOTREACHED */ |
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} |
|
|
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/* |
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* Secondly, handle the opcodes that don't embed their |
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* operands in the instruction. |
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*/ |
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switch (insn) { |
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case DW_CFA_nop: |
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continue; |
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case DW_CFA_advance_loc1: |
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delta = *current_insn++; |
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frame->pc += delta * cie->code_alignment_factor; |
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break; |
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case DW_CFA_advance_loc2: |
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delta = get_unaligned((u16 *)current_insn); |
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current_insn += 2; |
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frame->pc += delta * cie->code_alignment_factor; |
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break; |
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case DW_CFA_advance_loc4: |
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delta = get_unaligned((u32 *)current_insn); |
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current_insn += 4; |
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frame->pc += delta * cie->code_alignment_factor; |
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break; |
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case DW_CFA_offset_extended: |
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count = dwarf_read_uleb128(current_insn, ®); |
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current_insn += count; |
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count = dwarf_read_uleb128(current_insn, &offset); |
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current_insn += count; |
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offset *= cie->data_alignment_factor; |
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break; |
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case DW_CFA_restore_extended: |
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count = dwarf_read_uleb128(current_insn, ®); |
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current_insn += count; |
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break; |
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case DW_CFA_undefined: |
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count = dwarf_read_uleb128(current_insn, ®); |
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current_insn += count; |
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regp = dwarf_frame_alloc_reg(frame, reg); |
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regp->flags |= DWARF_UNDEFINED; |
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break; |
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case DW_CFA_def_cfa: |
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count = dwarf_read_uleb128(current_insn, |
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&frame->cfa_register); |
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current_insn += count; |
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count = dwarf_read_uleb128(current_insn, |
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&frame->cfa_offset); |
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current_insn += count; |
|
|
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frame->flags |= DWARF_FRAME_CFA_REG_OFFSET; |
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break; |
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case DW_CFA_def_cfa_register: |
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count = dwarf_read_uleb128(current_insn, |
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&frame->cfa_register); |
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current_insn += count; |
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frame->flags |= DWARF_FRAME_CFA_REG_OFFSET; |
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break; |
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case DW_CFA_def_cfa_offset: |
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count = dwarf_read_uleb128(current_insn, &offset); |
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current_insn += count; |
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frame->cfa_offset = offset; |
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break; |
|
case DW_CFA_def_cfa_expression: |
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count = dwarf_read_uleb128(current_insn, &expr_len); |
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current_insn += count; |
|
|
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frame->cfa_expr = current_insn; |
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frame->cfa_expr_len = expr_len; |
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current_insn += expr_len; |
|
|
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frame->flags |= DWARF_FRAME_CFA_REG_EXP; |
|
break; |
|
case DW_CFA_offset_extended_sf: |
|
count = dwarf_read_uleb128(current_insn, ®); |
|
current_insn += count; |
|
count = dwarf_read_leb128(current_insn, &offset); |
|
current_insn += count; |
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offset *= cie->data_alignment_factor; |
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regp = dwarf_frame_alloc_reg(frame, reg); |
|
regp->flags |= DWARF_REG_OFFSET; |
|
regp->addr = offset; |
|
break; |
|
case DW_CFA_val_offset: |
|
count = dwarf_read_uleb128(current_insn, ®); |
|
current_insn += count; |
|
count = dwarf_read_leb128(current_insn, &offset); |
|
offset *= cie->data_alignment_factor; |
|
regp = dwarf_frame_alloc_reg(frame, reg); |
|
regp->flags |= DWARF_VAL_OFFSET; |
|
regp->addr = offset; |
|
break; |
|
case DW_CFA_GNU_args_size: |
|
count = dwarf_read_uleb128(current_insn, &offset); |
|
current_insn += count; |
|
break; |
|
case DW_CFA_GNU_negative_offset_extended: |
|
count = dwarf_read_uleb128(current_insn, ®); |
|
current_insn += count; |
|
count = dwarf_read_uleb128(current_insn, &offset); |
|
offset *= cie->data_alignment_factor; |
|
|
|
regp = dwarf_frame_alloc_reg(frame, reg); |
|
regp->flags |= DWARF_REG_OFFSET; |
|
regp->addr = -offset; |
|
break; |
|
default: |
|
pr_debug("unhandled DWARF instruction 0x%x\n", insn); |
|
UNWINDER_BUG(); |
|
break; |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* dwarf_free_frame - free the memory allocated for @frame |
|
* @frame: the frame to free |
|
*/ |
|
void dwarf_free_frame(struct dwarf_frame *frame) |
|
{ |
|
dwarf_frame_free_regs(frame); |
|
mempool_free(frame, dwarf_frame_pool); |
|
} |
|
|
|
extern void ret_from_irq(void); |
|
|
|
/** |
|
* dwarf_unwind_stack - unwind the stack |
|
* |
|
* @pc: address of the function to unwind |
|
* @prev: struct dwarf_frame of the previous stackframe on the callstack |
|
* |
|
* Return a struct dwarf_frame representing the most recent frame |
|
* on the callstack. Each of the lower (older) stack frames are |
|
* linked via the "prev" member. |
|
*/ |
|
struct dwarf_frame *dwarf_unwind_stack(unsigned long pc, |
|
struct dwarf_frame *prev) |
|
{ |
|
struct dwarf_frame *frame; |
|
struct dwarf_cie *cie; |
|
struct dwarf_fde *fde; |
|
struct dwarf_reg *reg; |
|
unsigned long addr; |
|
|
|
/* |
|
* If we've been called in to before initialization has |
|
* completed, bail out immediately. |
|
*/ |
|
if (!dwarf_unwinder_ready) |
|
return NULL; |
|
|
|
/* |
|
* If we're starting at the top of the stack we need get the |
|
* contents of a physical register to get the CFA in order to |
|
* begin the virtual unwinding of the stack. |
|
* |
|
* NOTE: the return address is guaranteed to be setup by the |
|
* time this function makes its first function call. |
|
*/ |
|
if (!pc || !prev) |
|
pc = _THIS_IP_; |
|
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
|
/* |
|
* If our stack has been patched by the function graph tracer |
|
* then we might see the address of return_to_handler() where we |
|
* expected to find the real return address. |
|
*/ |
|
if (pc == (unsigned long)&return_to_handler) { |
|
struct ftrace_ret_stack *ret_stack; |
|
|
|
ret_stack = ftrace_graph_get_ret_stack(current, 0); |
|
if (ret_stack) |
|
pc = ret_stack->ret; |
|
/* |
|
* We currently have no way of tracking how many |
|
* return_to_handler()'s we've seen. If there is more |
|
* than one patched return address on our stack, |
|
* complain loudly. |
|
*/ |
|
WARN_ON(ftrace_graph_get_ret_stack(current, 1)); |
|
} |
|
#endif |
|
|
|
frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC); |
|
if (!frame) { |
|
printk(KERN_ERR "Unable to allocate a dwarf frame\n"); |
|
UNWINDER_BUG(); |
|
} |
|
|
|
INIT_LIST_HEAD(&frame->reg_list); |
|
frame->flags = 0; |
|
frame->prev = prev; |
|
frame->return_addr = 0; |
|
|
|
fde = dwarf_lookup_fde(pc); |
|
if (!fde) { |
|
/* |
|
* This is our normal exit path. There are two reasons |
|
* why we might exit here, |
|
* |
|
* a) pc has no asscociated DWARF frame info and so |
|
* we don't know how to unwind this frame. This is |
|
* usually the case when we're trying to unwind a |
|
* frame that was called from some assembly code |
|
* that has no DWARF info, e.g. syscalls. |
|
* |
|
* b) the DEBUG info for pc is bogus. There's |
|
* really no way to distinguish this case from the |
|
* case above, which sucks because we could print a |
|
* warning here. |
|
*/ |
|
goto bail; |
|
} |
|
|
|
cie = dwarf_lookup_cie(fde->cie_pointer); |
|
|
|
frame->pc = fde->initial_location; |
|
|
|
/* CIE initial instructions */ |
|
dwarf_cfa_execute_insns(cie->initial_instructions, |
|
cie->instructions_end, cie, fde, |
|
frame, pc); |
|
|
|
/* FDE instructions */ |
|
dwarf_cfa_execute_insns(fde->instructions, fde->end, cie, |
|
fde, frame, pc); |
|
|
|
/* Calculate the CFA */ |
|
switch (frame->flags) { |
|
case DWARF_FRAME_CFA_REG_OFFSET: |
|
if (prev) { |
|
reg = dwarf_frame_reg(prev, frame->cfa_register); |
|
UNWINDER_BUG_ON(!reg); |
|
UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET); |
|
|
|
addr = prev->cfa + reg->addr; |
|
frame->cfa = __raw_readl(addr); |
|
|
|
} else { |
|
/* |
|
* Again, we're starting from the top of the |
|
* stack. We need to physically read |
|
* the contents of a register in order to get |
|
* the Canonical Frame Address for this |
|
* function. |
|
*/ |
|
frame->cfa = dwarf_read_arch_reg(frame->cfa_register); |
|
} |
|
|
|
frame->cfa += frame->cfa_offset; |
|
break; |
|
default: |
|
UNWINDER_BUG(); |
|
} |
|
|
|
reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG); |
|
|
|
/* |
|
* If we haven't seen the return address register or the return |
|
* address column is undefined then we must assume that this is |
|
* the end of the callstack. |
|
*/ |
|
if (!reg || reg->flags == DWARF_UNDEFINED) |
|
goto bail; |
|
|
|
UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET); |
|
|
|
addr = frame->cfa + reg->addr; |
|
frame->return_addr = __raw_readl(addr); |
|
|
|
/* |
|
* Ah, the joys of unwinding through interrupts. |
|
* |
|
* Interrupts are tricky - the DWARF info needs to be _really_ |
|
* accurate and unfortunately I'm seeing a lot of bogus DWARF |
|
* info. For example, I've seen interrupts occur in epilogues |
|
* just after the frame pointer (r14) had been restored. The |
|
* problem was that the DWARF info claimed that the CFA could be |
|
* reached by using the value of the frame pointer before it was |
|
* restored. |
|
* |
|
* So until the compiler can be trusted to produce reliable |
|
* DWARF info when it really matters, let's stop unwinding once |
|
* we've calculated the function that was interrupted. |
|
*/ |
|
if (prev && prev->pc == (unsigned long)ret_from_irq) |
|
frame->return_addr = 0; |
|
|
|
return frame; |
|
|
|
bail: |
|
dwarf_free_frame(frame); |
|
return NULL; |
|
} |
|
|
|
static int dwarf_parse_cie(void *entry, void *p, unsigned long len, |
|
unsigned char *end, struct module *mod) |
|
{ |
|
struct rb_node **rb_node = &cie_root.rb_node; |
|
struct rb_node *parent = *rb_node; |
|
struct dwarf_cie *cie; |
|
unsigned long flags; |
|
int count; |
|
|
|
cie = kzalloc(sizeof(*cie), GFP_KERNEL); |
|
if (!cie) |
|
return -ENOMEM; |
|
|
|
cie->length = len; |
|
|
|
/* |
|
* Record the offset into the .eh_frame section |
|
* for this CIE. It allows this CIE to be |
|
* quickly and easily looked up from the |
|
* corresponding FDE. |
|
*/ |
|
cie->cie_pointer = (unsigned long)entry; |
|
|
|
cie->version = *(char *)p++; |
|
UNWINDER_BUG_ON(cie->version != 1); |
|
|
|
cie->augmentation = p; |
|
p += strlen(cie->augmentation) + 1; |
|
|
|
count = dwarf_read_uleb128(p, &cie->code_alignment_factor); |
|
p += count; |
|
|
|
count = dwarf_read_leb128(p, &cie->data_alignment_factor); |
|
p += count; |
|
|
|
/* |
|
* Which column in the rule table contains the |
|
* return address? |
|
*/ |
|
if (cie->version == 1) { |
|
cie->return_address_reg = __raw_readb(p); |
|
p++; |
|
} else { |
|
count = dwarf_read_uleb128(p, &cie->return_address_reg); |
|
p += count; |
|
} |
|
|
|
if (cie->augmentation[0] == 'z') { |
|
unsigned int length, count; |
|
cie->flags |= DWARF_CIE_Z_AUGMENTATION; |
|
|
|
count = dwarf_read_uleb128(p, &length); |
|
p += count; |
|
|
|
UNWINDER_BUG_ON((unsigned char *)p > end); |
|
|
|
cie->initial_instructions = p + length; |
|
cie->augmentation++; |
|
} |
|
|
|
while (*cie->augmentation) { |
|
/* |
|
* "L" indicates a byte showing how the |
|
* LSDA pointer is encoded. Skip it. |
|
*/ |
|
if (*cie->augmentation == 'L') { |
|
p++; |
|
cie->augmentation++; |
|
} else if (*cie->augmentation == 'R') { |
|
/* |
|
* "R" indicates a byte showing |
|
* how FDE addresses are |
|
* encoded. |
|
*/ |
|
cie->encoding = *(char *)p++; |
|
cie->augmentation++; |
|
} else if (*cie->augmentation == 'P') { |
|
/* |
|
* "R" indicates a personality |
|
* routine in the CIE |
|
* augmentation. |
|
*/ |
|
UNWINDER_BUG(); |
|
} else if (*cie->augmentation == 'S') { |
|
UNWINDER_BUG(); |
|
} else { |
|
/* |
|
* Unknown augmentation. Assume |
|
* 'z' augmentation. |
|
*/ |
|
p = cie->initial_instructions; |
|
UNWINDER_BUG_ON(!p); |
|
break; |
|
} |
|
} |
|
|
|
cie->initial_instructions = p; |
|
cie->instructions_end = end; |
|
|
|
/* Add to list */ |
|
spin_lock_irqsave(&dwarf_cie_lock, flags); |
|
|
|
while (*rb_node) { |
|
struct dwarf_cie *cie_tmp; |
|
|
|
cie_tmp = rb_entry(*rb_node, struct dwarf_cie, node); |
|
|
|
parent = *rb_node; |
|
|
|
if (cie->cie_pointer < cie_tmp->cie_pointer) |
|
rb_node = &parent->rb_left; |
|
else if (cie->cie_pointer >= cie_tmp->cie_pointer) |
|
rb_node = &parent->rb_right; |
|
else |
|
WARN_ON(1); |
|
} |
|
|
|
rb_link_node(&cie->node, parent, rb_node); |
|
rb_insert_color(&cie->node, &cie_root); |
|
|
|
#ifdef CONFIG_MODULES |
|
if (mod != NULL) |
|
list_add_tail(&cie->link, &mod->arch.cie_list); |
|
#endif |
|
|
|
spin_unlock_irqrestore(&dwarf_cie_lock, flags); |
|
|
|
return 0; |
|
} |
|
|
|
static int dwarf_parse_fde(void *entry, u32 entry_type, |
|
void *start, unsigned long len, |
|
unsigned char *end, struct module *mod) |
|
{ |
|
struct rb_node **rb_node = &fde_root.rb_node; |
|
struct rb_node *parent = *rb_node; |
|
struct dwarf_fde *fde; |
|
struct dwarf_cie *cie; |
|
unsigned long flags; |
|
int count; |
|
void *p = start; |
|
|
|
fde = kzalloc(sizeof(*fde), GFP_KERNEL); |
|
if (!fde) |
|
return -ENOMEM; |
|
|
|
fde->length = len; |
|
|
|
/* |
|
* In a .eh_frame section the CIE pointer is the |
|
* delta between the address within the FDE |
|
*/ |
|
fde->cie_pointer = (unsigned long)(p - entry_type - 4); |
|
|
|
cie = dwarf_lookup_cie(fde->cie_pointer); |
|
fde->cie = cie; |
|
|
|
if (cie->encoding) |
|
count = dwarf_read_encoded_value(p, &fde->initial_location, |
|
cie->encoding); |
|
else |
|
count = dwarf_read_addr(p, &fde->initial_location); |
|
|
|
p += count; |
|
|
|
if (cie->encoding) |
|
count = dwarf_read_encoded_value(p, &fde->address_range, |
|
cie->encoding & 0x0f); |
|
else |
|
count = dwarf_read_addr(p, &fde->address_range); |
|
|
|
p += count; |
|
|
|
if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) { |
|
unsigned int length; |
|
count = dwarf_read_uleb128(p, &length); |
|
p += count + length; |
|
} |
|
|
|
/* Call frame instructions. */ |
|
fde->instructions = p; |
|
fde->end = end; |
|
|
|
/* Add to list. */ |
|
spin_lock_irqsave(&dwarf_fde_lock, flags); |
|
|
|
while (*rb_node) { |
|
struct dwarf_fde *fde_tmp; |
|
unsigned long tmp_start, tmp_end; |
|
unsigned long start, end; |
|
|
|
fde_tmp = rb_entry(*rb_node, struct dwarf_fde, node); |
|
|
|
start = fde->initial_location; |
|
end = fde->initial_location + fde->address_range; |
|
|
|
tmp_start = fde_tmp->initial_location; |
|
tmp_end = fde_tmp->initial_location + fde_tmp->address_range; |
|
|
|
parent = *rb_node; |
|
|
|
if (start < tmp_start) |
|
rb_node = &parent->rb_left; |
|
else if (start >= tmp_end) |
|
rb_node = &parent->rb_right; |
|
else |
|
WARN_ON(1); |
|
} |
|
|
|
rb_link_node(&fde->node, parent, rb_node); |
|
rb_insert_color(&fde->node, &fde_root); |
|
|
|
#ifdef CONFIG_MODULES |
|
if (mod != NULL) |
|
list_add_tail(&fde->link, &mod->arch.fde_list); |
|
#endif |
|
|
|
spin_unlock_irqrestore(&dwarf_fde_lock, flags); |
|
|
|
return 0; |
|
} |
|
|
|
static void dwarf_unwinder_dump(struct task_struct *task, |
|
struct pt_regs *regs, |
|
unsigned long *sp, |
|
const struct stacktrace_ops *ops, |
|
void *data) |
|
{ |
|
struct dwarf_frame *frame, *_frame; |
|
unsigned long return_addr; |
|
|
|
_frame = NULL; |
|
return_addr = 0; |
|
|
|
while (1) { |
|
frame = dwarf_unwind_stack(return_addr, _frame); |
|
|
|
if (_frame) |
|
dwarf_free_frame(_frame); |
|
|
|
_frame = frame; |
|
|
|
if (!frame || !frame->return_addr) |
|
break; |
|
|
|
return_addr = frame->return_addr; |
|
ops->address(data, return_addr, 1); |
|
} |
|
|
|
if (frame) |
|
dwarf_free_frame(frame); |
|
} |
|
|
|
static struct unwinder dwarf_unwinder = { |
|
.name = "dwarf-unwinder", |
|
.dump = dwarf_unwinder_dump, |
|
.rating = 150, |
|
}; |
|
|
|
static void __init dwarf_unwinder_cleanup(void) |
|
{ |
|
struct dwarf_fde *fde, *next_fde; |
|
struct dwarf_cie *cie, *next_cie; |
|
|
|
/* |
|
* Deallocate all the memory allocated for the DWARF unwinder. |
|
* Traverse all the FDE/CIE lists and remove and free all the |
|
* memory associated with those data structures. |
|
*/ |
|
rbtree_postorder_for_each_entry_safe(fde, next_fde, &fde_root, node) |
|
kfree(fde); |
|
|
|
rbtree_postorder_for_each_entry_safe(cie, next_cie, &cie_root, node) |
|
kfree(cie); |
|
|
|
mempool_destroy(dwarf_reg_pool); |
|
mempool_destroy(dwarf_frame_pool); |
|
kmem_cache_destroy(dwarf_reg_cachep); |
|
kmem_cache_destroy(dwarf_frame_cachep); |
|
} |
|
|
|
/** |
|
* dwarf_parse_section - parse DWARF section |
|
* @eh_frame_start: start address of the .eh_frame section |
|
* @eh_frame_end: end address of the .eh_frame section |
|
* @mod: the kernel module containing the .eh_frame section |
|
* |
|
* Parse the information in a .eh_frame section. |
|
*/ |
|
static int dwarf_parse_section(char *eh_frame_start, char *eh_frame_end, |
|
struct module *mod) |
|
{ |
|
u32 entry_type; |
|
void *p, *entry; |
|
int count, err = 0; |
|
unsigned long len = 0; |
|
unsigned int c_entries, f_entries; |
|
unsigned char *end; |
|
|
|
c_entries = 0; |
|
f_entries = 0; |
|
entry = eh_frame_start; |
|
|
|
while ((char *)entry < eh_frame_end) { |
|
p = entry; |
|
|
|
count = dwarf_entry_len(p, &len); |
|
if (count == 0) { |
|
/* |
|
* We read a bogus length field value. There is |
|
* nothing we can do here apart from disabling |
|
* the DWARF unwinder. We can't even skip this |
|
* entry and move to the next one because 'len' |
|
* tells us where our next entry is. |
|
*/ |
|
err = -EINVAL; |
|
goto out; |
|
} else |
|
p += count; |
|
|
|
/* initial length does not include itself */ |
|
end = p + len; |
|
|
|
entry_type = get_unaligned((u32 *)p); |
|
p += 4; |
|
|
|
if (entry_type == DW_EH_FRAME_CIE) { |
|
err = dwarf_parse_cie(entry, p, len, end, mod); |
|
if (err < 0) |
|
goto out; |
|
else |
|
c_entries++; |
|
} else { |
|
err = dwarf_parse_fde(entry, entry_type, p, len, |
|
end, mod); |
|
if (err < 0) |
|
goto out; |
|
else |
|
f_entries++; |
|
} |
|
|
|
entry = (char *)entry + len + 4; |
|
} |
|
|
|
printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n", |
|
c_entries, f_entries); |
|
|
|
return 0; |
|
|
|
out: |
|
return err; |
|
} |
|
|
|
#ifdef CONFIG_MODULES |
|
int module_dwarf_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, |
|
struct module *me) |
|
{ |
|
unsigned int i, err; |
|
unsigned long start, end; |
|
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; |
|
|
|
start = end = 0; |
|
|
|
for (i = 1; i < hdr->e_shnum; i++) { |
|
/* Alloc bit cleared means "ignore it." */ |
|
if ((sechdrs[i].sh_flags & SHF_ALLOC) |
|
&& !strcmp(secstrings+sechdrs[i].sh_name, ".eh_frame")) { |
|
start = sechdrs[i].sh_addr; |
|
end = start + sechdrs[i].sh_size; |
|
break; |
|
} |
|
} |
|
|
|
/* Did we find the .eh_frame section? */ |
|
if (i != hdr->e_shnum) { |
|
INIT_LIST_HEAD(&me->arch.cie_list); |
|
INIT_LIST_HEAD(&me->arch.fde_list); |
|
err = dwarf_parse_section((char *)start, (char *)end, me); |
|
if (err) { |
|
printk(KERN_WARNING "%s: failed to parse DWARF info\n", |
|
me->name); |
|
return err; |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* module_dwarf_cleanup - remove FDE/CIEs associated with @mod |
|
* @mod: the module that is being unloaded |
|
* |
|
* Remove any FDEs and CIEs from the global lists that came from |
|
* @mod's .eh_frame section because @mod is being unloaded. |
|
*/ |
|
void module_dwarf_cleanup(struct module *mod) |
|
{ |
|
struct dwarf_fde *fde, *ftmp; |
|
struct dwarf_cie *cie, *ctmp; |
|
unsigned long flags; |
|
|
|
spin_lock_irqsave(&dwarf_cie_lock, flags); |
|
|
|
list_for_each_entry_safe(cie, ctmp, &mod->arch.cie_list, link) { |
|
list_del(&cie->link); |
|
rb_erase(&cie->node, &cie_root); |
|
kfree(cie); |
|
} |
|
|
|
spin_unlock_irqrestore(&dwarf_cie_lock, flags); |
|
|
|
spin_lock_irqsave(&dwarf_fde_lock, flags); |
|
|
|
list_for_each_entry_safe(fde, ftmp, &mod->arch.fde_list, link) { |
|
list_del(&fde->link); |
|
rb_erase(&fde->node, &fde_root); |
|
kfree(fde); |
|
} |
|
|
|
spin_unlock_irqrestore(&dwarf_fde_lock, flags); |
|
} |
|
#endif /* CONFIG_MODULES */ |
|
|
|
/** |
|
* dwarf_unwinder_init - initialise the dwarf unwinder |
|
* |
|
* Build the data structures describing the .dwarf_frame section to |
|
* make it easier to lookup CIE and FDE entries. Because the |
|
* .eh_frame section is packed as tightly as possible it is not |
|
* easy to lookup the FDE for a given PC, so we build a list of FDE |
|
* and CIE entries that make it easier. |
|
*/ |
|
static int __init dwarf_unwinder_init(void) |
|
{ |
|
int err = -ENOMEM; |
|
|
|
dwarf_frame_cachep = kmem_cache_create("dwarf_frames", |
|
sizeof(struct dwarf_frame), 0, |
|
SLAB_PANIC | SLAB_HWCACHE_ALIGN, NULL); |
|
|
|
dwarf_reg_cachep = kmem_cache_create("dwarf_regs", |
|
sizeof(struct dwarf_reg), 0, |
|
SLAB_PANIC | SLAB_HWCACHE_ALIGN, NULL); |
|
|
|
dwarf_frame_pool = mempool_create_slab_pool(DWARF_FRAME_MIN_REQ, |
|
dwarf_frame_cachep); |
|
if (!dwarf_frame_pool) |
|
goto out; |
|
|
|
dwarf_reg_pool = mempool_create_slab_pool(DWARF_REG_MIN_REQ, |
|
dwarf_reg_cachep); |
|
if (!dwarf_reg_pool) |
|
goto out; |
|
|
|
err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL); |
|
if (err) |
|
goto out; |
|
|
|
err = unwinder_register(&dwarf_unwinder); |
|
if (err) |
|
goto out; |
|
|
|
dwarf_unwinder_ready = 1; |
|
|
|
return 0; |
|
|
|
out: |
|
printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err); |
|
dwarf_unwinder_cleanup(); |
|
return err; |
|
} |
|
early_initcall(dwarf_unwinder_init);
|
|
|