1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include "private/KernelArgumentBlock.h" 30 31 extern const char linker_code_start; 32 extern const char original_start; 33 extern const char linker_entry; 34 35 /* 36 * This is the entry point for the linker wrapper, which finds 37 * the real linker, then bootstraps into it. 38 */ 39 extern "C" ElfW(Addr) __linker_init(void* raw_args) { 40 KernelArgumentBlock args(raw_args); 41 42 static uintptr_t linker_offset = reinterpret_cast<uintptr_t>(&linker_code_start); 43 static uintptr_t linktime_addr = reinterpret_cast<uintptr_t>(&linktime_addr); 44 ElfW(Addr) my_addr = reinterpret_cast<uintptr_t>(&linktime_addr) - linktime_addr; 45 46 // Set AT_ENTRY to the proper entry point 47 for (ElfW(auxv_t)* v = args.auxv; v->a_type != AT_NULL; ++v) { 48 if (v->a_type == AT_BASE) { 49 v->a_un.a_val = my_addr + linker_offset; 50 } 51 if (v->a_type == AT_ENTRY) { 52 v->a_un.a_val = my_addr + reinterpret_cast<uintptr_t>(&original_start); 53 } 54 } 55 56 // Return address of linker entry point -- may need to ensure that raw_args 57 // was saved. 58 return my_addr + linker_offset + reinterpret_cast<uintptr_t>(&linker_entry); 59 } 60
