18c2ecf20Sopenharmony_ci/* SPDX-License-Identifier: GPL-2.0-only */ 28c2ecf20Sopenharmony_ci/* 38c2ecf20Sopenharmony_ci * vvar.h: Shared vDSO/kernel variable declarations 48c2ecf20Sopenharmony_ci * Copyright (c) 2011 Andy Lutomirski 58c2ecf20Sopenharmony_ci * 68c2ecf20Sopenharmony_ci * A handful of variables are accessible (read-only) from userspace 78c2ecf20Sopenharmony_ci * code in the vsyscall page and the vdso. They are declared here. 88c2ecf20Sopenharmony_ci * Some other file must define them with DEFINE_VVAR. 98c2ecf20Sopenharmony_ci * 108c2ecf20Sopenharmony_ci * In normal kernel code, they are used like any other variable. 118c2ecf20Sopenharmony_ci * In user code, they are accessed through the VVAR macro. 128c2ecf20Sopenharmony_ci * 138c2ecf20Sopenharmony_ci * These variables live in a page of kernel data that has an extra RO 148c2ecf20Sopenharmony_ci * mapping for userspace. Each variable needs a unique offset within 158c2ecf20Sopenharmony_ci * that page; specify that offset with the DECLARE_VVAR macro. (If 168c2ecf20Sopenharmony_ci * you mess up, the linker will catch it.) 178c2ecf20Sopenharmony_ci */ 188c2ecf20Sopenharmony_ci 198c2ecf20Sopenharmony_ci#ifndef _ASM_X86_VVAR_H 208c2ecf20Sopenharmony_ci#define _ASM_X86_VVAR_H 218c2ecf20Sopenharmony_ci 228c2ecf20Sopenharmony_ci#ifdef EMIT_VVAR 238c2ecf20Sopenharmony_ci/* 248c2ecf20Sopenharmony_ci * EMIT_VVAR() is used by the kernel linker script to put vvars in the 258c2ecf20Sopenharmony_ci * right place. Also, it's used by kernel code to import offsets values. 268c2ecf20Sopenharmony_ci */ 278c2ecf20Sopenharmony_ci#define DECLARE_VVAR(offset, type, name) \ 288c2ecf20Sopenharmony_ci EMIT_VVAR(name, offset) 298c2ecf20Sopenharmony_ci 308c2ecf20Sopenharmony_ci#else 318c2ecf20Sopenharmony_ci 328c2ecf20Sopenharmony_ciextern char __vvar_page; 338c2ecf20Sopenharmony_ci 348c2ecf20Sopenharmony_ci#define DECLARE_VVAR(offset, type, name) \ 358c2ecf20Sopenharmony_ci extern type vvar_ ## name[CS_BASES] \ 368c2ecf20Sopenharmony_ci __attribute__((visibility("hidden"))); \ 378c2ecf20Sopenharmony_ci extern type timens_ ## name[CS_BASES] \ 388c2ecf20Sopenharmony_ci __attribute__((visibility("hidden"))); \ 398c2ecf20Sopenharmony_ci 408c2ecf20Sopenharmony_ci#define VVAR(name) (vvar_ ## name) 418c2ecf20Sopenharmony_ci#define TIMENS(name) (timens_ ## name) 428c2ecf20Sopenharmony_ci 438c2ecf20Sopenharmony_ci#define DEFINE_VVAR(type, name) \ 448c2ecf20Sopenharmony_ci type name[CS_BASES] \ 458c2ecf20Sopenharmony_ci __attribute__((section(".vvar_" #name), aligned(16))) __visible 468c2ecf20Sopenharmony_ci 478c2ecf20Sopenharmony_ci#endif 488c2ecf20Sopenharmony_ci 498c2ecf20Sopenharmony_ci/* DECLARE_VVAR(offset, type, name) */ 508c2ecf20Sopenharmony_ci 518c2ecf20Sopenharmony_ciDECLARE_VVAR(128, struct vdso_data, _vdso_data) 528c2ecf20Sopenharmony_ci 538c2ecf20Sopenharmony_ci#undef DECLARE_VVAR 548c2ecf20Sopenharmony_ci 558c2ecf20Sopenharmony_ci#endif 56