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aaf5420c | 1 | /* Create new context. |
688903eb | 2 | Copyright (C) 2012-2018 Free Software Foundation, Inc. |
aaf5420c AS |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
17 | <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #include <sysdep.h> | |
20 | ||
21 | #include "ucontext_i.h" | |
22 | ||
23 | ||
24 | ENTRY(__makecontext) | |
25 | move.l 4(%sp), %a0 | |
26 | ||
27 | /* Get the address of the function we are supposed to run. */ | |
28 | move.l 8(%sp), oPC(%a0) | |
29 | ||
30 | /* Compute the address of the stack. The information comes from | |
31 | to us_stack element. */ | |
32 | move.l oSS_SP(%a0), %a1 | |
33 | add.l oSS_SIZE(%a0), %a1 | |
34 | ||
35 | /* Remember the number of parameters for the exit handler since | |
36 | it has to remove them. We store the number in the D7 register | |
37 | which the function we will call must preserve. */ | |
38 | move.l 12(%sp), %d1 | |
39 | move.l %d1, oGREGS+7*4(%a0) | |
40 | ||
41 | /* Make room on the new stack for the parameters. | |
42 | Room for the arguments, return address (== 1f) and | |
43 | oLINK pointer is needed. */ | |
44 | neg.l %d1 | |
45 | lea -8(%a1,%d1.l*4), %a1 | |
46 | neg.l %d1 | |
47 | ||
48 | /* Store the future stack pointer. */ | |
49 | move.l %a1, oSP(%a0) | |
50 | ||
51 | /* Put the next context on the new stack (from the uc_link | |
52 | element). */ | |
53 | move.l oLINK(%a0), 4(%a1,%d1.l*4) | |
54 | ||
55 | /* Copy all the parameters. */ | |
56 | 1: subq.l #1,%d1 | |
57 | jmi 2f | |
58 | move.l 16(%sp,%d1.l*4), 4(%a1,%d1.l*4) | |
59 | jra 1b | |
60 | 2: | |
61 | ||
62 | /* If the function we call returns we must continue with the | |
63 | context which is given in the uc_link element. To do this | |
64 | set the return address for the function the user provides | |
65 | to a little bit of helper code which does the magic (see | |
66 | below). */ | |
67 | lea 1f(%pc), %a0 | |
68 | move.l %a0, (%a1) | |
69 | /* 'makecontext' returns no value. */ | |
70 | rts | |
71 | ||
72 | /* This is the helper code which gets called if a function which | |
73 | is registered with 'makecontext' returns. In this case we | |
74 | have to install the context listed in the uc_link element of | |
75 | the context 'makecontext' manipulated at the time of the | |
76 | 'makecontext' call. If the pointer is NULL the process must | |
bb1d31d0 AS |
77 | terminate. |
78 | Make sure to separate the return label from the previous unwind | |
79 | region, because the unwinder uses ra-1 to find the FDE. */ | |
aaf5420c | 80 | cfi_endproc |
bb1d31d0 | 81 | nop |
aaf5420c AS |
82 | 1: |
83 | /* This removes the parameters passed to the function given to | |
84 | 'makecontext' from the stack. D7 contains the number of | |
85 | parameters (see above). */ | |
86 | lea (%sp,%d7.l*4), %sp | |
87 | ||
88 | tst.l (%sp) /* Check the next context. */ | |
89 | jeq 2f /* If it is zero exit. */ | |
90 | ||
91 | jbsr JUMPTARGET(__setcontext) | |
92 | /* If this returns (which can happen if the syscall fails) we'll | |
93 | exit the program with the return error value (-1). */ | |
94 | ||
95 | move.l %d0, (%sp) | |
96 | 2: jbsr HIDDEN_JUMPTARGET(exit) | |
97 | /* The 'exit' call should never return. In case it does cause | |
98 | the process to terminate. */ | |
99 | illegal | |
100 | cfi_startproc | |
101 | END(__makecontext) | |
102 | ||
103 | weak_alias (__makecontext, makecontext) |