mirror of https://gitee.com/openkylin/linux.git
994 lines
24 KiB
C
994 lines
24 KiB
C
/*
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* Copyright (C) 2009 Matt Fleming <matt@console-pimps.org>
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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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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/* #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/ftrace.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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/* 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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static struct kmem_cache *dwarf_frame_cachep;
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static mempool_t *dwarf_frame_pool;
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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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static LIST_HEAD(dwarf_cie_list);
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static DEFINE_SPINLOCK(dwarf_cie_lock);
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static LIST_HEAD(dwarf_fde_list);
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static DEFINE_SPINLOCK(dwarf_fde_lock);
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static struct dwarf_cie *cached_cie;
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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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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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reg->number = reg_num;
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reg->addr = 0;
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reg->flags = 0;
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list_add(®->link, &frame->reg_list);
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return reg;
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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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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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* 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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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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return NULL;
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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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* 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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result = 0;
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shift = 0;
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count = 0;
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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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if (!(byte & 0x80))
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break;
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}
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*ret = result;
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return count;
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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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result = 0;
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shift = 0;
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count = 0;
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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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if (!(byte & 0x80))
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break;
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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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if ((shift < num_bits) && (byte & 0x40))
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result |= (-1 << shift);
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*ret = result;
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return count;
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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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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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if ((encoding & 0x07) == 0x00)
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encoding |= DW_EH_PE_udata4;
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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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return count;
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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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initial_len = get_unaligned((u32 *)addr);
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count = 4;
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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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* 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 dwarf_cie *cie;
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unsigned long flags;
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spin_lock_irqsave(&dwarf_cie_lock, flags);
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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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list_for_each_entry(cie, &dwarf_cie_list, link) {
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if (cie->cie_pointer == cie_ptr) {
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cached_cie = cie;
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break;
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}
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}
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/* Couldn't find the entry in the list. */
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if (&cie->link == &dwarf_cie_list)
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cie = NULL;
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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 dwarf_fde *fde;
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unsigned long flags;
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spin_lock_irqsave(&dwarf_fde_lock, flags);
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list_for_each_entry(fde, &dwarf_fde_list, link) {
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unsigned long start, end;
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start = fde->initial_location;
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end = fde->initial_location + fde->address_range;
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if (pc >= start && pc < end)
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break;
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}
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/* Couldn't find the entry in the list. */
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if (&fde->link == &dwarf_fde_list)
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fde = NULL;
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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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* 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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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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* 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;
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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;
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break;
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case DW_CFA_offset_extended_sf:
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count = dwarf_read_uleb128(current_insn, ®);
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current_insn += count;
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count = dwarf_read_leb128(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->flags |= DWARF_REG_OFFSET;
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regp->addr = offset;
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break;
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case DW_CFA_val_offset:
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count = dwarf_read_uleb128(current_insn, ®);
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current_insn += count;
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count = dwarf_read_leb128(current_insn, &offset);
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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->flags |= DWARF_VAL_OFFSET;
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regp->addr = offset;
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break;
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case DW_CFA_GNU_args_size:
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count = dwarf_read_uleb128(current_insn, &offset);
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current_insn += count;
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break;
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case DW_CFA_GNU_negative_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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offset *= cie->data_alignment_factor;
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regp = dwarf_frame_alloc_reg(frame, reg);
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regp->flags |= DWARF_REG_OFFSET;
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regp->addr = -offset;
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break;
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default:
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pr_debug("unhandled DWARF instruction 0x%x\n", insn);
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UNWINDER_BUG();
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break;
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}
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}
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return 0;
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}
|
|
|
|
/**
|
|
* dwarf_unwind_stack - recursively 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 this is the first invocation of this recursive function 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 = (unsigned long)current_text_addr();
|
|
|
|
#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) {
|
|
int index = current->curr_ret_stack;
|
|
|
|
/*
|
|
* 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(index > 0);
|
|
|
|
pc = current->ret_stack[index].ret;
|
|
}
|
|
#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 - the one that stops the
|
|
* recursion. There's 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, this is the first invocation of this
|
|
* recurisve function. 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);
|
|
|
|
return frame;
|
|
|
|
bail:
|
|
dwarf_frame_free_regs(frame);
|
|
mempool_free(frame, dwarf_frame_pool);
|
|
return NULL;
|
|
}
|
|
|
|
static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
|
|
unsigned char *end)
|
|
{
|
|
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);
|
|
list_add_tail(&cie->link, &dwarf_cie_list);
|
|
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 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);
|
|
list_add_tail(&fde->link, &dwarf_fde_list);
|
|
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_frame_free_regs(_frame);
|
|
mempool_free(_frame, dwarf_frame_pool);
|
|
}
|
|
|
|
_frame = frame;
|
|
|
|
if (!frame || !frame->return_addr)
|
|
break;
|
|
|
|
return_addr = frame->return_addr;
|
|
ops->address(data, return_addr, 1);
|
|
}
|
|
}
|
|
|
|
static struct unwinder dwarf_unwinder = {
|
|
.name = "dwarf-unwinder",
|
|
.dump = dwarf_unwinder_dump,
|
|
.rating = 150,
|
|
};
|
|
|
|
static void dwarf_unwinder_cleanup(void)
|
|
{
|
|
struct dwarf_cie *cie;
|
|
struct dwarf_fde *fde;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
list_for_each_entry(cie, &dwarf_cie_list, link)
|
|
kfree(cie);
|
|
|
|
list_for_each_entry(fde, &dwarf_fde_list, link)
|
|
kfree(fde);
|
|
|
|
kmem_cache_destroy(dwarf_reg_cachep);
|
|
kmem_cache_destroy(dwarf_frame_cachep);
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
u32 entry_type;
|
|
void *p, *entry;
|
|
int count, err = 0;
|
|
unsigned long len;
|
|
unsigned int c_entries, f_entries;
|
|
unsigned char *end;
|
|
INIT_LIST_HEAD(&dwarf_cie_list);
|
|
INIT_LIST_HEAD(&dwarf_fde_list);
|
|
|
|
c_entries = 0;
|
|
f_entries = 0;
|
|
entry = &__start_eh_frame;
|
|
|
|
dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
|
|
sizeof(struct dwarf_frame), 0,
|
|
SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
|
|
|
|
dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
|
|
sizeof(struct dwarf_reg), 0,
|
|
SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
|
|
|
|
dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
|
|
mempool_alloc_slab,
|
|
mempool_free_slab,
|
|
dwarf_frame_cachep);
|
|
|
|
dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
|
|
mempool_alloc_slab,
|
|
mempool_free_slab,
|
|
dwarf_reg_cachep);
|
|
|
|
while ((char *)entry < __stop_eh_frame) {
|
|
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.
|
|
*/
|
|
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);
|
|
if (err < 0)
|
|
goto out;
|
|
else
|
|
c_entries++;
|
|
} else {
|
|
err = dwarf_parse_fde(entry, entry_type, p, len, end);
|
|
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);
|
|
|
|
err = unwinder_register(&dwarf_unwinder);
|
|
if (err)
|
|
goto out;
|
|
|
|
return 0;
|
|
|
|
out:
|
|
printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
|
|
dwarf_unwinder_cleanup();
|
|
return -EINVAL;
|
|
}
|
|
early_initcall(dwarf_unwinder_init);
|