| /* |
| * 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.) |
| */ |
| |
| /* Base address of vvars. This is not ABI. */ |
| #define VVAR_ADDRESS (-10*1024*1024 - 4096) |
| |
| #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 |
| |
| #define DECLARE_VVAR(offset, type, name) \ |
| static type const * const vvaraddr_ ## name = \ |
| (void *)(VVAR_ADDRESS + (offset)); |
| |
| #define DEFINE_VVAR(type, name) \ |
| type name \ |
| __attribute__((section(".vvar_" #name), aligned(16))) |
| |
| #define VVAR(name) (*vvaraddr_ ## name) |
| |
| #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 |
