x86/entry: Remap the TSS into the CPU entry area

[mirror_ubuntu-artful-kernel.git] / arch / x86 / include / asm / fixmap.h

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 8c6ed66fe957ca10f1566f15c6c76e2cd49df5d0..c92fc30e6defec7e8c1c1dfadd661f34e244ea55 100644 (file)
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -54,6 +54,13 @@ extern unsigned long __FIXADDR_TOP;
  */
 struct cpu_entry_area {
        char gdt[PAGE_SIZE];
+
+       /*
+        * The GDT is just below cpu_tss and thus serves (on x86_64) as a
+        * a read-only guard page for the SYSENTER stack at the bottom
+        * of the TSS region.
+        */
+       struct tss_struct tss;
 };
 
 #define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE)