1/* Data structure for communication from the run-time dynamic linker for 2 loaded ELF shared objects. 3 Copyright (C) 1995-2001, 2004, 2005, 2006, 2010 Free Software Foundation, Inc. 4 This file is part of the GNU C Library. 5 6 The GNU C Library is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Lesser General Public 8 License as published by the Free Software Foundation; either 9 version 2.1 of the License, or (at your option) any later version. 10 11 The GNU C Library is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Lesser General Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with the GNU C Library; if not, write to the Free 18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 19 02111-1307 USA. */ 20 21#ifndef _LINK_H 22#define _LINK_H 1 23 24#include <features.h> 25#include <elf.h> 26#ifdef __HAVE_SHARED__ 27#include <dlfcn.h> 28#endif 29#include <sys/types.h> 30 31/* We use this macro to refer to ELF types independent of the native wordsize. 32 `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */ 33#define ElfW(type) _ElfW (Elf, __ELF_NATIVE_CLASS, type) 34#define _ElfW(e,w,t) _ElfW_1 (e, w, _##t) 35#define _ElfW_1(e,w,t) e##w##t 36 37#include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */ 38 39/* Rendezvous structure used by the run-time dynamic linker to communicate 40 details of shared object loading to the debugger. If the executable's 41 dynamic section has a DT_DEBUG element, the run-time linker sets that 42 element's value to the address where this structure can be found. */ 43 44struct r_debug 45 { 46 int r_version; /* Version number for this protocol. */ 47 48 struct link_map *r_map; /* Head of the chain of loaded objects. */ 49 50 /* This is the address of a function internal to the run-time linker, 51 that will always be called when the linker begins to map in a 52 library or unmap it, and again when the mapping change is complete. 53 The debugger can set a breakpoint at this address if it wants to 54 notice shared object mapping changes. */ 55 ElfW(Addr) r_brk; 56 enum 57 { 58 /* This state value describes the mapping change taking place when 59 the `r_brk' address is called. */ 60 RT_CONSISTENT, /* Mapping change is complete. */ 61 RT_ADD, /* Beginning to add a new object. */ 62 RT_DELETE /* Beginning to remove an object mapping. */ 63 } r_state; 64 65 ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */ 66 }; 67 68/* This is the instance of that structure used by the dynamic linker. */ 69extern struct r_debug _r_debug; 70 71/* This symbol refers to the "dynamic structure" in the `.dynamic' section 72 of whatever module refers to `_DYNAMIC'. So, to find its own 73 `struct r_debug', a program could do: 74 for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn) 75 if (dyn->d_tag == DT_DEBUG) 76 r_debug = (struct r_debug *) dyn->d_un.d_ptr; 77 */ 78extern ElfW(Dyn) _DYNAMIC[]; 79 80#ifdef __FDPIC__ 81# include <bits/elf-fdpic.h> 82#endif 83#ifdef __DSBT__ 84# include <bits/elf-dsbt.h> 85#endif 86 87/* Structure describing a loaded shared object. The `l_next' and `l_prev' 88 members form a chain of all the shared objects loaded at startup. 89 90 These data structures exist in space used by the run-time dynamic linker; 91 modifying them may have disastrous results. */ 92 93struct link_map 94 { 95 /* These first few members are part of the protocol with the debugger. 96 This is the same format used in SVR4. */ 97 98#ifdef __FDPIC__ 99 struct elf32_fdpic_loadaddr l_addr; 100#else 101#ifdef __DSBT__ 102 struct elf32_dsbt_loadaddr l_addr; 103#else 104 ElfW(Addr) l_addr; /* Base address shared object is loaded at. */ 105#endif 106#endif 107 char *l_name; /* Absolute file name object was found in. */ 108 ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */ 109 struct link_map *l_next, *l_prev; /* Chain of loaded objects. */ 110 111#if defined(USE_TLS) && USE_TLS 112 /* Thread-local storage related info. */ 113 114 /* Start of the initialization image. */ 115 void *l_tls_initimage; 116 /* Size of the initialization image. */ 117 size_t l_tls_initimage_size; 118 /* Size of the TLS block. */ 119 size_t l_tls_blocksize; 120 /* Alignment requirement of the TLS block. */ 121 size_t l_tls_align; 122 /* Offset of first byte module alignment. */ 123 size_t l_tls_firstbyte_offset; 124# ifndef NO_TLS_OFFSET 125# define NO_TLS_OFFSET 0 126# endif 127 /* For objects present at startup time: offset in the static TLS block. */ 128 ptrdiff_t l_tls_offset; 129 /* Index of the module in the dtv array. */ 130 size_t l_tls_modid; 131 /* Nonzero if _dl_init_static_tls should be called for this module */ 132 unsigned int l_need_tls_init:1; 133#endif 134 }; 135 136#ifdef __USE_GNU 137 138#if 0 139/* Version numbers for la_version handshake interface. */ 140#define LAV_CURRENT 1 141 142/* Activity types signaled through la_activity. */ 143enum 144 { 145 LA_ACT_CONSISTENT, /* Link map consistent again. */ 146 LA_ACT_ADD, /* New object will be added. */ 147 LA_ACT_DELETE /* Objects will be removed. */ 148 }; 149 150/* Values representing origin of name for dynamic loading. */ 151enum 152 { 153 LA_SER_ORIG = 0x01, /* Original name. */ 154 LA_SER_LIBPATH = 0x02, /* Directory from LD_LIBRARY_PATH. */ 155 LA_SER_RUNPATH = 0x04, /* Directory from RPATH/RUNPATH. */ 156 LA_SER_CONFIG = 0x08, /* Found through ldconfig. */ 157 LA_SER_DEFAULT = 0x40, /* Default directory. */ 158 LA_SER_SECURE = 0x80 /* Unused. */ 159 }; 160 161/* Values for la_objopen return value. */ 162enum 163 { 164 LA_FLG_BINDTO = 0x01, /* Audit symbols bound to this object. */ 165 LA_FLG_BINDFROM = 0x02 /* Audit symbols bound from this object. */ 166 }; 167 168/* Values for la_symbind flags parameter. */ 169enum 170 { 171 LA_SYMB_NOPLTENTER = 0x01, /* la_pltenter will not be called. */ 172 LA_SYMB_NOPLTEXIT = 0x02, /* la_pltexit will not be called. */ 173 LA_SYMB_STRUCTCALL = 0x04, /* Return value is a structure. */ 174 LA_SYMB_DLSYM = 0x08, /* Binding due to dlsym call. */ 175 LA_SYMB_ALTVALUE = 0x10 /* Value has been changed by a previous 176 la_symbind call. */ 177 }; 178#endif 179 180struct dl_phdr_info 181 { 182#ifdef __FDPIC__ 183 struct elf32_fdpic_loadaddr dlpi_addr; 184#else 185#ifdef __DSBT__ 186 struct elf32_dsbt_loadaddr dlpi_addr; 187#else 188 ElfW(Addr) dlpi_addr; 189#endif 190#endif 191 const char *dlpi_name; 192 const ElfW(Phdr) *dlpi_phdr; 193 ElfW(Half) dlpi_phnum; 194 195#if 0 196 /* Note: Following members were introduced after the first 197 version of this structure was available. Check the SIZE 198 argument passed to the dl_iterate_phdr callback to determine 199 whether or not each later member is available. */ 200 201 /* Incremented when a new object may have been added. */ 202 unsigned long long int dlpi_adds; 203 /* Incremented when an object may have been removed. */ 204 unsigned long long int dlpi_subs; 205 206 /* If there is a PT_TLS segment, its module ID as used in 207 TLS relocations, else zero. */ 208 size_t dlpi_tls_modid; 209 210 /* The address of the calling thread's instance of this module's 211 PT_TLS segment, if it has one and it has been allocated 212 in the calling thread, otherwise a null pointer. */ 213 void *dlpi_tls_data; 214#endif 215 }; 216 217__BEGIN_DECLS 218 219extern int dl_iterate_phdr (int (*__callback) (struct dl_phdr_info *, 220 size_t, void *), 221 void *__data); 222 223 224#if 0 225/* Prototypes for the ld.so auditing interfaces. These are not 226 defined anywhere in ld.so but instead have to be provided by the 227 auditing DSO. */ 228extern unsigned int la_version (unsigned int __version); 229extern void la_activity (uintptr_t *__cookie, unsigned int __flag); 230extern char *la_objsearch (const char *__name, uintptr_t *__cookie, 231 unsigned int __flag); 232extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid, 233 uintptr_t *__cookie); 234extern void la_preinit (uintptr_t *__cookie); 235extern uintptr_t la_symbind32 (Elf32_Sym *__sym, unsigned int __ndx, 236 uintptr_t *__refcook, uintptr_t *__defcook, 237 unsigned int *__flags, const char *__symname); 238extern uintptr_t la_symbind64 (Elf64_Sym *__sym, unsigned int __ndx, 239 uintptr_t *__refcook, uintptr_t *__defcook, 240 unsigned int *__flags, const char *__symname); 241extern unsigned int la_objclose (uintptr_t *__cookie); 242#endif 243 244__END_DECLS 245 246#endif 247 248#endif /* link.h */ 249