| /* |
| * 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. |
| * |
| * Each of these variables lives in the vsyscall page, and each |
| * one needs a unique offset within the little piece of the page |
| * reserved for vvars. Specify that offset in DECLARE_VVAR. |
| * (There are 896 bytes available. If you mess up, the linker will |
| * catch it.) |
| */ |
| |
| /* Offset of vars within vsyscall page */ |
| #define VSYSCALL_VARS_OFFSET (3072 + 128) |
| |
| #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, VSYSCALL_VARS_OFFSET + offset) |
| |
| #else |
| |
| #define DECLARE_VVAR(offset, type, name) \ |
| static type const * const vvaraddr_ ## name = \ |
| (void *)(VSYSCALL_START + VSYSCALL_VARS_OFFSET + (offset)); |
| |
| #define DEFINE_VVAR(type, name) \ |
| type __vvar_ ## name \ |
| __attribute__((section(".vsyscall_var_" #name), aligned(16))) |
| |
| #define VVAR(name) (*vvaraddr_ ## name) |
| |
| #endif |
| |
| /* DECLARE_VVAR(offset, type, name) */ |
| |
| DECLARE_VVAR(0, volatile unsigned long, jiffies) |
| DECLARE_VVAR(8, int, vgetcpu_mode) |
| DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data) |
| |
| #undef DECLARE_VVAR |
| #undef VSYSCALL_VARS_OFFSET |
