1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef __ANDROID_DLEXT_H__ 18 #define __ANDROID_DLEXT_H__ 19 20 #include <stddef.h> 21 #include <stdint.h> 22 #include <sys/cdefs.h> 23 #include <sys/types.h> /* for off64_t */ 24 25 __BEGIN_DECLS 26 27 /* bitfield definitions for android_dlextinfo.flags */ 28 enum { 29 /* When set, the reserved_addr and reserved_size fields must point to an 30 * already-reserved region of address space which will be used to load the 31 * library if it fits. If the reserved region is not large enough, the load 32 * will fail. 33 */ 34 ANDROID_DLEXT_RESERVED_ADDRESS = 0x1, 35 36 /* As DLEXT_RESERVED_ADDRESS, but if the reserved region is not large enough, 37 * the linker will choose an available address instead. 38 */ 39 ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2, 40 41 /* When set, write the GNU RELRO section of the mapped library to relro_fd 42 * after relocation has been performed, to allow it to be reused by another 43 * process loading the same library at the same address. This implies 44 * ANDROID_DLEXT_USE_RELRO. 45 */ 46 ANDROID_DLEXT_WRITE_RELRO = 0x4, 47 48 /* When set, compare the GNU RELRO section of the mapped library to relro_fd 49 * after relocation has been performed, and replace any relocated pages that 50 * are identical with a version mapped from the file. 51 */ 52 ANDROID_DLEXT_USE_RELRO = 0x8, 53 54 /* Instruct dlopen to use library_fd instead of opening file by name. 55 * The filename parameter is still used to identify the library. 56 */ 57 ANDROID_DLEXT_USE_LIBRARY_FD = 0x10, 58 59 /* If opening a library using library_fd read it starting at library_fd_offset. 60 * This flag is only valid when ANDROID_DLEXT_USE_LIBRARY_FD is set. 61 */ 62 ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET = 0x20, 63 64 /* When set, do not check if the library has already been loaded by file stat(2)s. 65 * 66 * This flag allows forced loading of the library in the case when for some 67 * reason multiple ELF files share the same filename (because the already-loaded 68 * library has been removed and overwritten, for example). 69 * 70 * Note that if the library has the same dt_soname as an old one and some other 71 * library has the soname in DT_NEEDED list, the first one will be used to resolve any 72 * dependencies. 73 */ 74 ANDROID_DLEXT_FORCE_LOAD = 0x40, 75 76 /* When set, if the minimum p_vaddr of the ELF file's PT_LOAD segments is non-zero, 77 * the dynamic linker will load it at that address. 78 * 79 * This flag is for ART internal use only. 80 */ 81 ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80, 82 83 /* Instructs dlopen to load the library at the address specified by reserved_addr. 84 * 85 * The difference between ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS and ANDROID_DLEXT_RESERVED_ADDRESS 86 * is that for ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS the linker reserves memory at reserved_addr 87 * whereas for ANDROID_DLEXT_RESERVED_ADDRESS the linker relies on the caller to reserve the memory. 88 * 89 * This flag can be used with ANDROID_DLEXT_FORCE_FIXED_VADDR; when ANDROID_DLEXT_FORCE_FIXED_VADDR 90 * is set and load_bias is not 0 (load_bias is min(p_vaddr) of PT_LOAD segments) this flag is ignored. 91 * This is implemented this way because the linker has to pick one address over the other and this 92 * way is more convenient for art. Note that ANDROID_DLEXT_FORCE_FIXED_VADDR does not generate 93 * an error when min(p_vaddr) is 0. 94 * 95 * Cannot be used with ANDROID_DLEXT_RESERVED_ADDRESS or ANDROID_DLEXT_RESERVED_ADDRESS_HINT. 96 * 97 * This flag is for ART internal use only. 98 */ 99 ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100, 100 101 /* This flag used to load library in a different namespace. The namespace is 102 * specified in library_namespace. 103 */ 104 ANDROID_DLEXT_USE_NAMESPACE = 0x200, 105 106 /* Mask of valid bits */ 107 ANDROID_DLEXT_VALID_FLAG_BITS = ANDROID_DLEXT_RESERVED_ADDRESS | 108 ANDROID_DLEXT_RESERVED_ADDRESS_HINT | 109 ANDROID_DLEXT_WRITE_RELRO | 110 ANDROID_DLEXT_USE_RELRO | 111 ANDROID_DLEXT_USE_LIBRARY_FD | 112 ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET | 113 ANDROID_DLEXT_FORCE_LOAD | 114 ANDROID_DLEXT_FORCE_FIXED_VADDR | 115 ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS | 116 ANDROID_DLEXT_USE_NAMESPACE, 117 }; 118 119 struct android_namespace_t; 120 121 typedef struct { 122 uint64_t flags; 123 void* reserved_addr; 124 size_t reserved_size; 125 int relro_fd; 126 int library_fd; 127 off64_t library_fd_offset; 128 struct android_namespace_t* library_namespace; 129 } android_dlextinfo; 130 131 extern void* android_dlopen_ext(const char* filename, int flag, const android_dlextinfo* extinfo); 132 133 __END_DECLS 134 135 #endif /* __ANDROID_DLEXT_H__ */ 136
