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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 | * ---------------------------------------------------------------------------------- * | |
b32b8144 | 15 | * | fc_mxcsr|fc_x87_cw| R12 | R13 | R14 | * |
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16 | * ---------------------------------------------------------------------------------- * |
17 | * ---------------------------------------------------------------------------------- * | |
18 | * | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | * | |
19 | * ---------------------------------------------------------------------------------- * | |
20 | * | 0x20 | 0x24 | 0x28 | 0x2c | 0x30 | 0x34 | 0x38 | 0x3c | * | |
21 | * ---------------------------------------------------------------------------------- * | |
b32b8144 | 22 | * | R15 | RBX | RBP | RIP | * |
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23 | * ---------------------------------------------------------------------------------- * |
24 | * * | |
25 | ****************************************************************************************/ | |
26 | ||
27 | .text | |
28 | .globl _make_fcontext | |
29 | .align 8 | |
30 | _make_fcontext: | |
31 | /* first arg of make_fcontext() == top of context-stack */ | |
32 | movq %rdi, %rax | |
33 | ||
34 | /* shift address in RAX to lower 16 byte boundary */ | |
b32b8144 | 35 | andq $-16, %rax |
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36 | |
37 | /* reserve space for context-data on context-stack */ | |
38 | /* on context-function entry: (RSP -0x8) % 16 == 0 */ | |
39 | leaq -0x40(%rax), %rax | |
40 | ||
41 | /* third arg of make_fcontext() == address of context-function */ | |
b32b8144 FG |
42 | /* stored in RBX */ |
43 | movq %rdx, 0x28(%rax) | |
44 | ||
45 | /* save MMX control- and status-word */ | |
46 | stmxcsr (%rax) | |
47 | /* save x87 control-word */ | |
48 | fnstcw 0x4(%rax) | |
49 | ||
50 | /* compute abs address of label trampoline */ | |
51 | leaq trampoline(%rip), %rcx | |
52 | /* save address of trampoline as return-address for context-function */ | |
53 | /* will be entered after calling jump_fcontext() first time */ | |
54 | movq %rcx, 0x38(%rax) | |
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55 | |
56 | /* compute abs address of label finish */ | |
57 | leaq finish(%rip), %rcx | |
58 | /* save address of finish as return-address for context-function */ | |
59 | /* will be entered after context-function returns */ | |
b32b8144 | 60 | movq %rcx, 0x30(%rax) |
7c673cae FG |
61 | |
62 | ret /* return pointer to context-data */ | |
63 | ||
b32b8144 FG |
64 | trampoline: |
65 | /* store return address on stack */ | |
66 | /* fix stack alignment */ | |
67 | push %rbp | |
68 | /* jump to context-function */ | |
69 | jmp *%rbx | |
70 | ||
7c673cae FG |
71 | finish: |
72 | /* exit code is zero */ | |
73 | xorq %rdi, %rdi | |
74 | /* exit application */ | |
75 | call __exit | |
76 | hlt |