x86/entry/64: Make cpu_entry_area.tss read-only

[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 b65155cc3760a72b49b680c3f70923ddedf684d2..5dc269ff408556a45ed313d202d064544f8fa188 100644 (file)
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -44,6 +44,45 @@ extern unsigned long __FIXADDR_TOP;
                         PAGE_SIZE)
 #endif
 
+/*
+ * cpu_entry_area is a percpu region in the fixmap that contains things
+ * needed by the CPU and early entry/exit code.  Real types aren't used
+ * for all fields here to avoid circular header dependencies.
+ *
+ * Every field is a virtual alias of some other allocated backing store.
+ * There is no direct allocation of a struct cpu_entry_area.
+ */
+struct cpu_entry_area {
+       char gdt[PAGE_SIZE];
+
+       /*
+        * The GDT is just below SYSENTER_stack and thus serves (on x86_64) as
+        * a a read-only guard page.
+        */
+       struct SYSENTER_stack_page SYSENTER_stack_page;
+
+       /*
+        * On x86_64, the TSS is mapped RO.  On x86_32, it's mapped RW because
+        * we need task switches to work, and task switches write to the TSS.
+        */
+       struct tss_struct tss;
+
+       char entry_trampoline[PAGE_SIZE];
+
+#ifdef CONFIG_X86_64
+       /*
+        * Exception stacks used for IST entries.
+        *
+        * In the future, this should have a separate slot for each stack
+        * with guard pages between them.
+        */
+       char exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ];
+#endif
+};
+
+#define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE)
+
+extern void setup_cpu_entry_areas(void);
 
 /*
  * Here we define all the compile-time 'special' virtual
@@ -101,8 +140,14 @@ enum fixed_addresses {
        FIX_LNW_VRTC,
 #endif
        /* Fixmap entries to remap the GDTs, one per processor. */
-       FIX_GDT_REMAP_BEGIN,
-       FIX_GDT_REMAP_END = FIX_GDT_REMAP_BEGIN + NR_CPUS - 1,
+       FIX_CPU_ENTRY_AREA_TOP,
+       FIX_CPU_ENTRY_AREA_BOTTOM = FIX_CPU_ENTRY_AREA_TOP + (CPU_ENTRY_AREA_PAGES * NR_CPUS) - 1,
+
+#ifdef CONFIG_ACPI_APEI_GHES
+       /* Used for GHES mapping from assorted contexts */
+       FIX_APEI_GHES_IRQ,
+       FIX_APEI_GHES_NMI,
+#endif
 
        __end_of_permanent_fixed_addresses,
 
@@ -165,5 +210,30 @@ static inline void __set_fixmap(enum fixed_addresses idx,
 void __early_set_fixmap(enum fixed_addresses idx,
                        phys_addr_t phys, pgprot_t flags);
 
+static inline unsigned int __get_cpu_entry_area_page_index(int cpu, int page)
+{
+       BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0);
+
+       return FIX_CPU_ENTRY_AREA_BOTTOM - cpu*CPU_ENTRY_AREA_PAGES - page;
+}
+
+#define __get_cpu_entry_area_offset_index(cpu, offset) ({              \
+       BUILD_BUG_ON(offset % PAGE_SIZE != 0);                          \
+       __get_cpu_entry_area_page_index(cpu, offset / PAGE_SIZE);       \
+       })
+
+#define get_cpu_entry_area_index(cpu, field)                           \
+       __get_cpu_entry_area_offset_index((cpu), offsetof(struct cpu_entry_area, field))
+
+static inline struct cpu_entry_area *get_cpu_entry_area(int cpu)
+{
+       return (struct cpu_entry_area *)__fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0));
+}
+
+static inline struct SYSENTER_stack *cpu_SYSENTER_stack(int cpu)
+{
+       return &get_cpu_entry_area(cpu)->SYSENTER_stack_page.stack;
+}
+
 #endif /* !__ASSEMBLY__ */
 #endif /* _ASM_X86_FIXMAP_H */