]>
Commit | Line | Data |
---|---|---|
2b778ceb | 1 | /* Copyright (C) 2002-2021 Free Software Foundation, Inc. |
c816e074 AJ |
2 | This file is part of the GNU C Library. |
3 | Contributed by Andreas Jaeger <aj@suse.de>, 2002. | |
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 | |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
c816e074 AJ |
18 | |
19 | #include <sysdep.h> | |
20 | ||
25123a1c L |
21 | #if SHSTK_ENABLED |
22 | # include <asm/prctl.h> | |
23 | # include "ucontext_i.h" | |
24 | ||
25 | /* Use CALL to push __start_context onto the new stack as well as the new | |
26 | shadow stack. RDI points to ucontext: | |
27 | Incoming: | |
28 | __ssp[0]: The original caller's shadow stack pointer. | |
29 | __ssp[1]: The size of the new shadow stack. | |
30 | __ssp[2]: The size of the new shadow stack. | |
31 | Outgoing: | |
32 | __ssp[0]: The new shadow stack pointer. | |
33 | __ssp[1]: The base address of the new shadow stack. | |
34 | __ssp[2]: The size of the new shadow stack. | |
35 | */ | |
36 | ||
37 | ENTRY(__push___start_context) | |
38 | /* Save the pointer to ucontext. */ | |
39 | movq %rdi, %r9 | |
40 | /* Get the original shadow stack pointer. */ | |
41 | rdsspq %r8 | |
42 | /* Save the original stack pointer. */ | |
43 | movq %rsp, %rdx | |
44 | /* Load the top of the new stack into RSI. */ | |
45 | movq oRSP(%rdi), %rsi | |
46 | /* Add 8 bytes to RSI since CALL will push the 8-byte return | |
47 | address onto stack. */ | |
48 | leaq 8(%rsi), %rsp | |
49 | /* Allocate the new shadow stack. The size of the new shadow | |
50 | stack is passed in __ssp[1]. */ | |
51 | lea (oSSP + 8)(%rdi), %RSI_LP | |
52 | movl $ARCH_CET_ALLOC_SHSTK, %edi | |
53 | movl $__NR_arch_prctl, %eax | |
54 | /* The new shadow stack base is returned in __ssp[1]. */ | |
55 | syscall | |
56 | testq %rax, %rax | |
57 | jne L(hlt) /* This should never happen. */ | |
58 | ||
59 | /* Get the size of the new shadow stack. */ | |
60 | movq 8(%rsi), %rdi | |
61 | ||
62 | /* Get the base address of the new shadow stack. */ | |
63 | movq (%rsi), %rsi | |
64 | ||
65 | /* Use the restore stoken to restore the new shadow stack. */ | |
66 | rstorssp -8(%rsi, %rdi) | |
67 | ||
68 | /* Save the restore token on the original shadow stack. */ | |
69 | saveprevssp | |
70 | ||
71 | /* Push the address of "jmp __start_context" onto the new stack | |
72 | as well as the new shadow stack. */ | |
73 | call 1f | |
74 | jmp __start_context | |
75 | 1: | |
76 | ||
77 | /* Get the new shadow stack pointer. */ | |
78 | rdsspq %rdi | |
79 | ||
80 | /* Use the restore stoken to restore the original shadow stack. */ | |
81 | rstorssp -8(%r8) | |
82 | ||
83 | /* Save the restore token on the new shadow stack. */ | |
84 | saveprevssp | |
85 | ||
86 | /* Store the new shadow stack pointer in __ssp[0]. */ | |
87 | movq %rdi, oSSP(%r9) | |
88 | ||
89 | /* Restore the original stack. */ | |
90 | mov %rdx, %rsp | |
91 | ret | |
92 | END(__push___start_context) | |
93 | #endif | |
94 | ||
c816e074 AJ |
95 | /* This is the helper code which gets called if a function which is |
96 | registered with 'makecontext' returns. In this case we have to | |
97 | install the context listed in the uc_link element of the context | |
98 | 'makecontext' manipulated at the time of the 'makecontext' call. | |
99 | If the pointer is NULL the process must terminate. */ | |
100 | ||
101 | ||
102 | ENTRY(__start_context) | |
103 | /* This removes the parameters passed to the function given to | |
104 | 'makecontext' from the stack. RBX contains the address | |
105 | on the stack pointer for the next context. */ | |
106 | movq %rbx, %rsp | |
107 | ||
8e1f3464 L |
108 | /* Don't use pop here so that stack is aligned to 16 bytes. */ |
109 | movq (%rsp), %rdi /* This is the next context. */ | |
c816e074 AJ |
110 | testq %rdi, %rdi |
111 | je 2f /* If it is zero exit. */ | |
112 | ||
521266a8 | 113 | call __setcontext |
c816e074 AJ |
114 | /* If this returns (which can happen if the syscall fails) we'll |
115 | exit the program with the return error value (-1). */ | |
f7db3170 | 116 | movq %rax,%rdi |
c816e074 | 117 | |
f7db3170 | 118 | 2: |
ea493b56 | 119 | call HIDDEN_JUMPTARGET(exit) |
c816e074 AJ |
120 | /* The 'exit' call should never return. In case it does cause |
121 | the process to terminate. */ | |
25123a1c | 122 | L(hlt): |
c816e074 AJ |
123 | hlt |
124 | END(__start_context) |