1 /* SPDX-License-Identifier: GPL-2.0-only */ 1
2 /*
3 * vvar.h: Shared vDSO/kernel variable declara
4 * Copyright (c) 2011 Andy Lutomirski
5 *
6 * A handful of variables are accessible (read
7 * code in the vsyscall page and the vdso. Th
8 * Some other file must define them with DEFIN
9 *
10 * In normal kernel code, they are used like a
11 * In user code, they are accessed through the
12 *
13 * These variables live in a page of kernel da
14 * mapping for userspace. Each variable needs
15 * that page; specify that offset with the DEC
16 * you mess up, the linker will catch it.)
17 */
18
19 #ifndef _ASM_X86_VVAR_H
20 #define _ASM_X86_VVAR_H
21
22 #ifdef EMIT_VVAR
23 /*
24 * EMIT_VVAR() is used by the kernel linker sc
25 * right place. Also, it's used by kernel code
26 */
27 #define DECLARE_VVAR(offset, type, name) \
28 EMIT_VVAR(name, offset)
29 #define DECLARE_VVAR_SINGLE(offset, type, name
30 EMIT_VVAR(name, offset)
31
32 #else
33
34 extern char __vvar_page;
35
36 #define DECLARE_VVAR(offset, type, name)
37 extern type vvar_ ## name[CS_BASES]
38 __attribute__((visibility("hidden")));
39 extern type timens_ ## name[CS_BASES]
40 __attribute__((visibility("hidden")));
41
42 #define DECLARE_VVAR_SINGLE(offset, type, name
43 extern type vvar_ ## name
44 __attribute__((visibility("hidden")));
45
46 #define VVAR(name) (vvar_ ## name)
47 #define TIMENS(name) (timens_ ## name)
48
49 #define DEFINE_VVAR(type, name)
50 type name[CS_BASES]
51 __attribute__((section(".vvar_" #name)
52
53 #define DEFINE_VVAR_SINGLE(type, name)
54 type name
55 __attribute__((section(".vvar_" #name)
56
57 #endif
58
59 /* DECLARE_VVAR(offset, type, name) */
60
61 DECLARE_VVAR(128, struct vdso_data, _vdso_data
62
63 #if !defined(_SINGLE_DATA)
64 #define _SINGLE_DATA
65 DECLARE_VVAR_SINGLE(640, struct vdso_rng_data,
66 #endif
67
68 #undef DECLARE_VVAR
69 #undef DECLARE_VVAR_SINGLE
70
71 #endif
72
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