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 <stdbool.h> 21 #include <stddef.h> 22 #include <stdint.h> 23 #include <sys/cdefs.h> 24 #include <sys/types.h> /* for off64_t */ 25 26 __BEGIN_DECLS 27 28 /* bitfield definitions for android_dlextinfo.flags */ 29 enum { 30 /* When set, the reserved_addr and reserved_size fields must point to an 31 * already-reserved region of address space which will be used to load the 32 * library if it fits. If the reserved region is not large enough, the load 33 * will fail. 34 */ 35 ANDROID_DLEXT_RESERVED_ADDRESS = 0x1, 36 37 /* As DLEXT_RESERVED_ADDRESS, but if the reserved region is not large enough, 38 * the linker will choose an available address instead. 39 */ 40 ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2, 41 42 /* When set, write the GNU RELRO section of the mapped library to relro_fd 43 * after relocation has been performed, to allow it to be reused by another 44 * process loading the same library at the same address. This implies 45 * ANDROID_DLEXT_USE_RELRO. 46 */ 47 ANDROID_DLEXT_WRITE_RELRO = 0x4, 48 49 /* When set, compare the GNU RELRO section of the mapped library to relro_fd 50 * after relocation has been performed, and replace any relocated pages that 51 * are identical with a version mapped from the file. 52 */ 53 ANDROID_DLEXT_USE_RELRO = 0x8, 54 55 /* Instruct dlopen to use library_fd instead of opening file by name. 56 * The filename parameter is still used to identify the library. 57 */ 58 ANDROID_DLEXT_USE_LIBRARY_FD = 0x10, 59 60 /* If opening a library using library_fd read it starting at library_fd_offset. 61 * This flag is only valid when ANDROID_DLEXT_USE_LIBRARY_FD is set. 62 */ 63 ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET = 0x20, 64 65 /* When set, do not check if the library has already been loaded by file stat(2)s. 66 * 67 * This flag allows forced loading of the library in the case when for some 68 * reason multiple ELF files share the same filename (because the already-loaded 69 * library has been removed and overwritten, for example). 70 * 71 * Note that if the library has the same dt_soname as an old one and some other 72 * library has the soname in DT_NEEDED list, the first one will be used to resolve any 73 * dependencies. 74 */ 75 ANDROID_DLEXT_FORCE_LOAD = 0x40, 76 77 /* When set, if the minimum p_vaddr of the ELF file's PT_LOAD segments is non-zero, 78 * the dynamic linker will load it at that address. 79 * 80 * This flag is for ART internal use only. 81 */ 82 ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80, 83 84 /* Instructs dlopen to load the library at the address specified by reserved_addr. 85 * 86 * The difference between ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS and ANDROID_DLEXT_RESERVED_ADDRESS 87 * is that for ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS the linker reserves memory at reserved_addr 88 * whereas for ANDROID_DLEXT_RESERVED_ADDRESS the linker relies on the caller to reserve the memory. 89 * 90 * This flag can be used with ANDROID_DLEXT_FORCE_FIXED_VADDR; when ANDROID_DLEXT_FORCE_FIXED_VADDR 91 * is set and load_bias is not 0 (load_bias is min(p_vaddr) of PT_LOAD segments) this flag is ignored. 92 * This is implemented this way because the linker has to pick one address over the other and this 93 * way is more convenient for art. Note that ANDROID_DLEXT_FORCE_FIXED_VADDR does not generate 94 * an error when min(p_vaddr) is 0. 95 * 96 * Cannot be used with ANDROID_DLEXT_RESERVED_ADDRESS or ANDROID_DLEXT_RESERVED_ADDRESS_HINT. 97 * 98 * This flag is for ART internal use only. 99 */ 100 ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100, 101 102 /* This flag used to load library in a different namespace. The namespace is 103 * specified in library_namespace. 104 */ 105 ANDROID_DLEXT_USE_NAMESPACE = 0x200, 106 107 /* Mask of valid bits */ 108 ANDROID_DLEXT_VALID_FLAG_BITS = ANDROID_DLEXT_RESERVED_ADDRESS | 109 ANDROID_DLEXT_RESERVED_ADDRESS_HINT | 110 ANDROID_DLEXT_WRITE_RELRO | 111 ANDROID_DLEXT_USE_RELRO | 112 ANDROID_DLEXT_USE_LIBRARY_FD | 113 ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET | 114 ANDROID_DLEXT_FORCE_LOAD | 115 ANDROID_DLEXT_FORCE_FIXED_VADDR | 116 ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS | 117 ANDROID_DLEXT_USE_NAMESPACE, 118 }; 119 120 struct android_namespace_t; 121 122 typedef struct { 123 uint64_t flags; 124 void* reserved_addr; 125 size_t reserved_size; 126 int relro_fd; 127 int library_fd; 128 off64_t library_fd_offset; 129 struct android_namespace_t* library_namespace; 130 } android_dlextinfo; 131 132 void* android_dlopen_ext(const char* filename, int flag, const android_dlextinfo* extinfo) 133 __INTRODUCED_IN(21); 134 135 __END_DECLS 136 137 #endif /* __ANDROID_DLEXT_H__ */ 138