1 /* libunwind - a platform-independent unwind library 2 Copyright (c) 2003 Hewlett-Packard Development Company, L.P. 3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com> 4 5 This file is part of libunwind. 6 7 Permission is hereby granted, free of charge, to any person obtaining 8 a copy of this software and associated documentation files (the 9 "Software"), to deal in the Software without restriction, including 10 without limitation the rights to use, copy, modify, merge, publish, 11 distribute, sublicense, and/or sell copies of the Software, and to 12 permit persons to whom the Software is furnished to do so, subject to 13 the following conditions: 14 15 The above copyright notice and this permission notice shall be 16 included in all copies or substantial portions of the Software. 17 18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 19 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 20 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 21 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 22 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 24 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ 25 26 #ifndef dwarf_eh_h 27 #define dwarf_eh_h 28 29 #include "dwarf.h" 30 31 /* This header file defines the format of a DWARF exception-header 32 section (.eh_frame_hdr, pointed to by program-header 33 PT_GNU_EH_FRAME). The exception-header is self-describing in the 34 sense that the format of the addresses contained in it is expressed 35 as a one-byte type-descriptor called a "pointer-encoding" (PE). 36 37 The exception header encodes the address of the .eh_frame section 38 and optionally contains a binary search table for the 39 Frame Descriptor Entries (FDEs) in the .eh_frame. The contents of 40 .eh_frame has the format described by the DWARF v3 standard 41 (http://www.eagercon.com/dwarf/dwarf3std.htm), except that code 42 addresses may be encoded in different ways. Also, .eh_frame has 43 augmentations that allow encoding a language-specific data-area 44 (LSDA) pointer and a pointer to a personality-routine. 45 46 Details: 47 48 The Common Information Entry (CIE) associated with an FDE may 49 contain an augmentation string. Each character in this string has 50 a specific meaning and either one or two associated operands. The 51 operands are stored in an augmentation body which appears right 52 after the "return_address_register" member and before the 53 "initial_instructions" member. The operands appear in the order 54 in which the characters appear in the string. For example, if the 55 augmentation string is "zL", the operand for 'z' would be first in 56 the augmentation body and the operand for 'L' would be second. 57 The following characters are supported for the CIE augmentation 58 string: 59 60 'z': The operand for this character is a uleb128 value that gives the 61 length of the CIE augmentation body, not counting the length 62 of the uleb128 operand itself. If present, this code must 63 appear as the first character in the augmentation body. 64 65 'L': Indicates that the FDE's augmentation body contains an LSDA 66 pointer. The operand for this character is a single byte 67 that specifies the pointer-encoding (PE) that is used for 68 the LSDA pointer. 69 70 'R': Indicates that the code-pointers (FDE members 71 "initial_location" and "address_range" and the operand for 72 DW_CFA_set_loc) in the FDE have a non-default encoding. The 73 operand for this character is a single byte that specifies 74 the pointer-encoding (PE) that is used for the 75 code-pointers. Note: the "address_range" member is always 76 encoded as an absolute value. Apart from that, the specified 77 FDE pointer-encoding applies. 78 79 'P': Indicates the presence of a personality routine (handler). 80 The first operand for this character specifies the 81 pointer-encoding (PE) that is used for the second operand, 82 which specifies the address of the personality routine. 83 84 If the augmentation string contains any other characters, the 85 remainder of the augmentation string should be ignored. 86 Furthermore, if the size of the augmentation body is unknown 87 (i.e., 'z' is not the first character of the augmentation string), 88 then the entire CIE as well all associated FDEs must be ignored. 89 90 A Frame Descriptor Entries (FDE) may contain an augmentation body 91 which, if present, appears right after the "address_range" member 92 and before the "instructions" member. The contents of this body 93 is implicitly defined by the augmentation string of the associated 94 CIE. The meaning of the characters in the CIE's augmentation 95 string as far as FDEs are concerned is as follows: 96 97 'z': The first operand in the FDE's augmentation body specifies 98 the total length of the augmentation body as a uleb128 (not 99 counting the length of the uleb128 operand itself). 100 101 'L': The operand for this character is an LSDA pointer, encoded 102 in the format specified by the corresponding operand in the 103 CIE's augmentation body. 104 105 */ 106 107 #define DW_EH_VERSION 1 /* The version we're implementing */ 108 109 struct dwarf_eh_frame_hdr 110 { 111 unsigned char version; 112 unsigned char eh_frame_ptr_enc; 113 unsigned char fde_count_enc; 114 unsigned char table_enc; 115 /* The rest of the header is variable-length and consists of the 116 following members: 117 118 encoded_t eh_frame_ptr; 119 encoded_t fde_count; 120 struct 121 { 122 encoded_t start_ip; // first address covered by this FDE 123 encoded_t fde_addr; // address of the FDE 124 } 125 binary_search_table[fde_count]; */ 126 }; 127 128 #endif /* dwarf_eh_h */ 129