1/*
 2 * vvar.h: Shared vDSO/kernel variable declarations
 3 * Copyright (c) 2011 Andy Lutomirski
 4 * Subject to the GNU General Public License, version 2
 5 *
 6 * A handful of variables are accessible (read-only) from userspace
 7 * code in the vsyscall page and the vdso.  They are declared here.
 8 * Some other file must define them with DEFINE_VVAR.
 9 *
10 * In normal kernel code, they are used like any other variable.
11 * In user code, they are accessed through the VVAR macro.
12 *
13 * These variables live in a page of kernel data that has an extra RO
14 * mapping for userspace.  Each variable needs a unique offset within
15 * that page; specify that offset with the DECLARE_VVAR macro.  (If
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#if defined(__VVAR_KERNEL_LDS)
23
24/* The kernel linker script defines its own magic to put vvars in the
25 * right place.
26 */
27#define DECLARE_VVAR(offset, type, name) \
28	EMIT_VVAR(name, offset)
29
30#else
31
32extern char __vvar_page;
33
34#define DECLARE_VVAR(offset, type, name)				\
35	extern type vvar_ ## name __attribute__((visibility("hidden")));
 
 
 
36
37#define VVAR(name) (vvar_ ## name)
 
38
39#define DEFINE_VVAR(type, name)						\
40	type name							\
41	__attribute__((section(".vvar_" #name), aligned(16))) __visible
42
43#endif
44
45/* DECLARE_VVAR(offset, type, name) */
46
47DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
48
49#undef DECLARE_VVAR
50
51#endif

 1/* SPDX-License-Identifier: GPL-2.0-only */
 2/*
 3 * vvar.h: Shared vDSO/kernel variable declarations
 4 * Copyright (c) 2011 Andy Lutomirski
 
 5 *
 6 * A handful of variables are accessible (read-only) from userspace
 7 * code in the vsyscall page and the vdso.  They are declared here.
 8 * Some other file must define them with DEFINE_VVAR.
 9 *
10 * In normal kernel code, they are used like any other variable.
11 * In user code, they are accessed through the VVAR macro.
12 *
13 * These variables live in a page of kernel data that has an extra RO
14 * mapping for userspace.  Each variable needs a unique offset within
15 * that page; specify that offset with the DECLARE_VVAR macro.  (If
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 script to put vvars in the
25 * right place. Also, it's used by kernel code to import offsets values.
26 */
27#define DECLARE_VVAR(offset, type, name) \
28	EMIT_VVAR(name, offset)
29
30#else
31
32extern char __vvar_page;
33
34#define DECLARE_VVAR(offset, type, name)				\
35	extern type vvar_ ## name[CS_BASES]				\
36	__attribute__((visibility("hidden")));				\
37	extern type timens_ ## name[CS_BASES]				\
38	__attribute__((visibility("hidden")));				\
39
40#define VVAR(name) (vvar_ ## name)
41#define TIMENS(name) (timens_ ## name)
42
43#define DEFINE_VVAR(type, name)						\
44	type name[CS_BASES]						\
45	__attribute__((section(".vvar_" #name), aligned(16))) __visible
46
47#endif
48
49/* DECLARE_VVAR(offset, type, name) */
50
51DECLARE_VVAR(128, struct vdso_data, _vdso_data)
52
53#undef DECLARE_VVAR
54
55#endif