x86-64: Give vvars their own page

[mirror_ubuntu-bionic-kernel.git] / arch / x86 / include / asm / vvar.h

diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h
index a4eaca4a61336fd89c798597008e44f4a390fe56..de656ac2af415ce85c760cb28962576848044a3b 100644 (file)
--- a/arch/x86/include/asm/vvar.h
+++ b/arch/x86/include/asm/vvar.h
@@ -10,15 +10,14 @@
  * 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.)
+ * 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.)
  */
 
-/* Offset of vars within vsyscall page */
-#define VSYSCALL_VARS_OFFSET (3072 + 128)
+/* Base address of vvars.  This is not ABI. */
+#define VVAR_ADDRESS (-10*1024*1024 - 4096)
 
 #if defined(__VVAR_KERNEL_LDS)
 
@@ -26,17 +25,17 @@
  * right place.
  */
 #define DECLARE_VVAR(offset, type, name) \
-       EMIT_VVAR(name, VSYSCALL_VARS_OFFSET + offset)
+       EMIT_VVAR(name, offset)
 
 #else
 
 #define DECLARE_VVAR(offset, type, name)                               \
        static type const * const vvaraddr_ ## name =                   \
-               (void *)(VSYSCALL_START + VSYSCALL_VARS_OFFSET + (offset));
+               (void *)(VVAR_ADDRESS + (offset));
 
 #define DEFINE_VVAR(type, name)                                                \
-       type __vvar_ ## name                                            \
-       __attribute__((section(".vsyscall_var_" #name), aligned(16)))
+       type name                                                       \
+       __attribute__((section(".vvar_" #name), aligned(16)))
 
 #define VVAR(name) (*vvaraddr_ ## name)
 
@@ -49,4 +48,3 @@ DECLARE_VVAR(16, int, vgetcpu_mode)
 DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
 
 #undef DECLARE_VVAR
-#undef VSYSCALL_VARS_OFFSET