1/* 2 Copyright Oliver Kowalke 2009. 3 Distributed under the Boost Software License, Version 1.0. 4 (See accompanying file LICENSE_1_0.txt or copy at 5 http://www.boost.org/LICENSE_1_0.txt) 6*/ 7 8/**************************************************************************************** 9 * * 10 * ---------------------------------------------------------------------------------- * 11 * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | * 12 * ---------------------------------------------------------------------------------- * 13 * | 0x0 | 0x4 | 0x8 | 0xc | 0x10 | 0x14 | 0x18 | 0x1c | * 14 * ---------------------------------------------------------------------------------- * 15 * | fc_mxcsr|fc_x87_cw| guard | EDI | ESI | EBX | EBP | EIP | * 16 * ---------------------------------------------------------------------------------- * 17 * ---------------------------------------------------------------------------------- * 18 * | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | * 19 * ---------------------------------------------------------------------------------- * 20 * | 0x20 | 0x24 | 0x28 | | * 21 * ---------------------------------------------------------------------------------- * 22 * | hidden | to | data | | * 23 * ---------------------------------------------------------------------------------- * 24 * * 25 ****************************************************************************************/ 26 27.file "make_i386_sysv_elf_gas.S" 28.text 29.globl make_fcontext 30.align 2 31.type make_fcontext,@function 32make_fcontext: 33 /* first arg of make_fcontext() == top of context-stack */ 34 movl 0x4(%esp), %eax 35 36 /* reserve space for first argument of context-function 37 eax might already point to a 16byte border */ 38 leal -0x8(%eax), %eax 39 40 /* shift address in EAX to lower 16 byte boundary */ 41 andl $-16, %eax 42 43 /* reserve space for context-data on context-stack, and align the stack */ 44 leal -0x34(%eax), %eax 45 46 /* third arg of make_fcontext() == address of context-function */ 47 /* stored in EBX */ 48 movl 0xc(%esp), %ecx 49 movl %ecx, 0x14(%eax) 50 51 /* save MMX control- and status-word */ 52 stmxcsr (%eax) 53 /* save x87 control-word */ 54 fnstcw 0x4(%eax) 55 56#if defined(BOOST_CONTEXT_TLS_STACK_PROTECTOR) 57 /* save stack guard */ 58 movl %gs:0x14, %ecx /* read stack guard from TLS record */ 59 movl %ecx, 0x8(%eax) /* save stack guard */ 60#endif 61 62 /* return transport_t */ 63 /* FCTX == EDI, DATA == ESI */ 64 leal 0xc(%eax), %ecx 65 movl %ecx, 0x20(%eax) 66 67 /* compute abs address of label trampoline */ 68 call 1f 69 /* address of trampoline 1 */ 701: popl %ecx 71 /* compute abs address of label trampoline */ 72 addl $trampoline-1b, %ecx 73 /* save address of trampoline as return address */ 74 /* will be entered after calling jump_fcontext() first time */ 75 movl %ecx, 0x1c(%eax) 76 77 /* compute abs address of label finish */ 78 call 2f 79 /* address of label 2 */ 802: popl %ecx 81 /* compute abs address of label finish */ 82 addl $finish-2b, %ecx 83 /* save address of finish as return-address for context-function */ 84 /* will be entered after context-function returns */ 85 movl %ecx, 0x18(%eax) 86 87 ret /* return pointer to context-data */ 88 89trampoline: 90 /* move transport_t for entering context-function */ 91 movl %edi, (%esp) 92 movl %esi, 0x4(%esp) 93 pushl %ebp 94 /* jump to context-function */ 95 jmp *%ebx 96 97finish: 98 call 3f 99 /* address of label 3 */ 1003: popl %ebx 101 /* compute address of GOT and store it in EBX */ 102 addl $_GLOBAL_OFFSET_TABLE_+[.-3b], %ebx 103 104 /* exit code is zero */ 105 xorl %eax, %eax 106 movl %eax, (%esp) 107 /* exit application */ 108 call _exit@PLT 109 hlt 110.size make_fcontext,.-make_fcontext 111 112/* Mark that we don't need executable stack. */ 113.section .note.GNU-stack,"",%progbits 114
