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f33632cc | 1 | /* Internal header file for <setjmp.h>. Linux/x86 version. |
04277e02 | 2 | Copyright (C) 2017-2019 Free Software Foundation, Inc. |
f33632cc L |
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 | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
f33632cc L |
18 | |
19 | #ifndef _SETJMPP_H | |
20 | #define _SETJMPP_H 1 | |
21 | ||
22 | #include <bits/types/__sigset_t.h> | |
d6cc1829 | 23 | #include <libc-pointer-arith.h> |
f33632cc | 24 | |
d6cc1829 L |
25 | /* <setjmp/setjmp.h> has |
26 | ||
27 | struct __jmp_buf_tag | |
28 | { | |
29 | __jmp_buf __jmpbuf; | |
30 | int __mask_was_saved; | |
31 | __sigset_t __saved_mask; | |
32 | }; | |
33 | ||
34 | struct __jmp_buf_tag is 32 bits aligned on i386 and is 64 bits | |
35 | aligned on x32 and x86-64. __saved_mask is aligned to 32 bits | |
36 | on i386/x32 without padding and is aligned to 64 bits on x86-64 | |
37 | with 32 bit padding. | |
38 | ||
39 | and <nptl/descr.h> has | |
40 | ||
41 | struct pthread_unwind_buf | |
42 | { | |
43 | struct | |
44 | { | |
45 | __jmp_buf jmp_buf; | |
46 | int mask_was_saved; | |
47 | } cancel_jmp_buf[1]; | |
48 | ||
49 | union | |
50 | { | |
51 | void *pad[4]; | |
52 | struct | |
53 | { | |
54 | struct pthread_unwind_buf *prev; | |
55 | struct _pthread_cleanup_buffer *cleanup; | |
56 | int canceltype; | |
57 | } data; | |
58 | } priv; | |
59 | }; | |
60 | ||
61 | struct pthread_unwind_buf is 32 bits aligned on i386 and 64 bits | |
62 | aligned on x32/x86-64. cancel_jmp_buf is aligned to 32 bits on | |
63 | i386 and is aligned to 64 bits on x32/x86-64. | |
64 | ||
65 | The pad array in struct pthread_unwind_buf is used by setjmp to save | |
66 | shadow stack register. The usable space in __saved_mask for sigset | |
67 | and shadow stack pointer: | |
68 | 1. i386: The 4x4 byte pad array which can be used for 4 byte shadow | |
69 | stack pointer and maximum 12 byte sigset. | |
70 | 2. x32: 4 byte padding + the 4x4 byte pad array which can be used | |
71 | for 8 byte shadow stack pointer and maximum 12 byte sigset. | |
72 | 3. x86-64: The 4x8 byte pad array which can be used for 8 byte | |
73 | shadow stack pointer and maximum 24 byte sigset. | |
74 | ||
75 | NB: We use setjmp in thread cancellation and this saves the shadow | |
76 | stack register, but __libc_unwind_longjmp doesn't restore the shadow | |
77 | stack register since cancellation never returns after longjmp. */ | |
78 | ||
79 | /* Number of bits per long. */ | |
80 | #define _JUMP_BUF_SIGSET_BITS_PER_WORD (8 * sizeof (unsigned long int)) | |
81 | /* The biggest signal number. As of kernel 4.14, x86 _NSIG is 64. The | |
82 | common maximum sigset for i386, x32 and x86-64 is 12 bytes (96 bits). | |
83 | Define it to 96 to leave some rooms for future use. */ | |
84 | #define _JUMP_BUF_SIGSET_NSIG 96 | |
f33632cc L |
85 | /* Number of longs to hold all signals. */ |
86 | #define _JUMP_BUF_SIGSET_NWORDS \ | |
d6cc1829 L |
87 | (ALIGN_UP (_JUMP_BUF_SIGSET_NSIG, _JUMP_BUF_SIGSET_BITS_PER_WORD) \ |
88 | / _JUMP_BUF_SIGSET_BITS_PER_WORD) | |
f33632cc L |
89 | |
90 | typedef struct | |
91 | { | |
92 | unsigned long int __val[_JUMP_BUF_SIGSET_NWORDS]; | |
93 | } __jmp_buf_sigset_t; | |
94 | ||
95 | typedef union | |
96 | { | |
97 | __sigset_t __saved_mask_compat; | |
98 | struct | |
99 | { | |
100 | __jmp_buf_sigset_t __saved_mask; | |
d6cc1829 L |
101 | /* Used for shadow stack pointer. NB: Shadow stack pointer |
102 | must have the same alignment as __saved_mask. Otherwise | |
103 | offset of __saved_mask will be changed. */ | |
f33632cc L |
104 | unsigned long int __shadow_stack_pointer; |
105 | } __saved; | |
106 | } __jmpbuf_arch_t; | |
107 | ||
108 | #undef __sigset_t | |
109 | #define __sigset_t __jmpbuf_arch_t | |
110 | #include <setjmp.h> | |
111 | #undef __saved_mask | |
112 | #define __saved_mask __saved_mask.__saved.__saved_mask | |
113 | ||
114 | #include <signal.h> | |
115 | ||
116 | #define _SIGPROCMASK_NSIG_WORDS (_NSIG / (8 * sizeof (unsigned long int))) | |
117 | ||
118 | typedef struct | |
119 | { | |
120 | unsigned long int __val[_SIGPROCMASK_NSIG_WORDS]; | |
121 | } __sigprocmask_sigset_t; | |
122 | ||
123 | extern jmp_buf ___buf; | |
124 | extern __typeof (___buf[0].__saved_mask) ___saved_mask; | |
125 | _Static_assert (sizeof (___saved_mask) >= sizeof (__sigprocmask_sigset_t), | |
126 | "size of ___saved_mask < size of __sigprocmask_sigset_t"); | |
127 | ||
128 | #endif /* setjmpP.h */ |