| /* | |
| * vvar.h: Shared vDSO/kernel variable declarations | |
| * Copyright (c) 2011 Andy Lutomirski | |
| * Subject to the GNU General Public License, version 2 | |
| * | |
| * A handful of variables are accessible (read-only) from userspace | |
| * code in the vsyscall page and the vdso. They are declared here. | |
| * Some other file must define them with DEFINE_VVAR. | |
| * | |
| * In normal kernel code, they are used like any other variable. | |
| * In user code, they are accessed through the VVAR macro. | |
| * | |
| * These variables live in a page of kernel data that has an extra RO | |
| * mapping for userspace. Each variable needs a unique offset within | |
| * that page; specify that offset with the DECLARE_VVAR macro. (If | |
| * you mess up, the linker will catch it.) | |
| */ | |
| #ifndef _ASM_X86_VVAR_H | |
| #define _ASM_X86_VVAR_H | |
| #if defined(__VVAR_KERNEL_LDS) | |
| /* The kernel linker script defines its own magic to put vvars in the | |
| * right place. | |
| */ | |
| #define DECLARE_VVAR(offset, type, name) \ | |
| EMIT_VVAR(name, offset) | |
| #else | |
| extern char __vvar_page; | |
| #define DECLARE_VVAR(offset, type, name) \ | |
| extern type vvar_ ## name __attribute__((visibility("hidden"))); | |
| #define VVAR(name) (vvar_ ## name) | |
| #define DEFINE_VVAR(type, name) \ | |
| type name \ | |
| __attribute__((section(".vvar_" #name), aligned(16))) __visible | |
| #endif | |
| /* DECLARE_VVAR(offset, type, name) */ | |
| DECLARE_VVAR(0, volatile unsigned long, jiffies) | |
| DECLARE_VVAR(16, int, vgetcpu_mode) | |
| DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data) | |
| #undef DECLARE_VVAR | |
| #endif |