1 files changed, 157 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h
new file mode 100644
index 000000000..75efc4c6f
--- /dev/null
+++ b/arch/x86/include/asm/cpu_entry_area.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_X86_CPU_ENTRY_AREA_H
+#define _ASM_X86_CPU_ENTRY_AREA_H
+
+#include <linux/percpu-defs.h>
+#include <asm/processor.h>
+#include <asm/intel_ds.h>
+#include <asm/pgtable_areas.h>
+
+#ifdef CONFIG_X86_64
+
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+#define VC_EXCEPTION_STKSZ	EXCEPTION_STKSZ
+#else
+#define VC_EXCEPTION_STKSZ	0
+#endif
+
+/* Macro to enforce the same ordering and stack sizes */
+#define ESTACKS_MEMBERS(guardsize, optional_stack_size)		\
+	char	DF_stack_guard[guardsize];			\
+	char	DF_stack[EXCEPTION_STKSZ];			\
+	char	NMI_stack_guard[guardsize];			\
+	char	NMI_stack[EXCEPTION_STKSZ];			\
+	char	DB_stack_guard[guardsize];			\
+	char	DB_stack[EXCEPTION_STKSZ];			\
+	char	MCE_stack_guard[guardsize];			\
+	char	MCE_stack[EXCEPTION_STKSZ];			\
+	char	VC_stack_guard[guardsize];			\
+	char	VC_stack[optional_stack_size];			\
+	char	VC2_stack_guard[guardsize];			\
+	char	VC2_stack[optional_stack_size];			\
+	char	IST_top_guard[guardsize];			\
+
+/* The exception stacks' physical storage. No guard pages required */
+struct exception_stacks {
+	ESTACKS_MEMBERS(0, VC_EXCEPTION_STKSZ)
+};
+
+/* The effective cpu entry area mapping with guard pages. */
+struct cea_exception_stacks {
+	ESTACKS_MEMBERS(PAGE_SIZE, EXCEPTION_STKSZ)
+};
+
+/*
+ * The exception stack ordering in [cea_]exception_stacks
+ */
+enum exception_stack_ordering {
+	ESTACK_DF,
+	ESTACK_NMI,
+	ESTACK_DB,
+	ESTACK_MCE,
+	ESTACK_VC,
+	ESTACK_VC2,
+	N_EXCEPTION_STACKS
+};
+
+#define CEA_ESTACK_SIZE(st)					\
+	sizeof(((struct cea_exception_stacks *)0)->st## _stack)
+
+#define CEA_ESTACK_BOT(ceastp, st)				\
+	((unsigned long)&(ceastp)->st## _stack)
+
+#define CEA_ESTACK_TOP(ceastp, st)				\
+	(CEA_ESTACK_BOT(ceastp, st) + CEA_ESTACK_SIZE(st))
+
+#define CEA_ESTACK_OFFS(st)					\
+	offsetof(struct cea_exception_stacks, st## _stack)
+
+#define CEA_ESTACK_PAGES					\
+	(sizeof(struct cea_exception_stacks) / PAGE_SIZE)
+
+#endif
+
+#ifdef CONFIG_X86_32
+struct doublefault_stack {
+	unsigned long stack[(PAGE_SIZE - sizeof(struct x86_hw_tss)) / sizeof(unsigned long)];
+	struct x86_hw_tss tss;
+} __aligned(PAGE_SIZE);
+#endif
+
+/*
+ * cpu_entry_area is a percpu region 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 entry_stack and thus serves (on x86_64) as
+	 * a read-only guard page. On 32-bit the GDT must be writeable, so
+	 * it needs an extra guard page.
+	 */
+#ifdef CONFIG_X86_32
+	char guard_entry_stack[PAGE_SIZE];
+#endif
+	struct entry_stack_page entry_stack_page;
+
+#ifdef CONFIG_X86_32
+	char guard_doublefault_stack[PAGE_SIZE];
+	struct doublefault_stack doublefault_stack;
+#endif
+
+	/*
+	 * 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;
+
+#ifdef CONFIG_X86_64
+	/*
+	 * Exception stacks used for IST entries with guard pages.
+	 */
+	struct cea_exception_stacks estacks;
+#endif
+	/*
+	 * Per CPU debug store for Intel performance monitoring. Wastes a
+	 * full page at the moment.
+	 */
+	struct debug_store cpu_debug_store;
+	/*
+	 * The actual PEBS/BTS buffers must be mapped to user space
+	 * Reserve enough fixmap PTEs.
+	 */
+	struct debug_store_buffers cpu_debug_buffers;
+};
+
+#define CPU_ENTRY_AREA_SIZE		(sizeof(struct cpu_entry_area))
+#define CPU_ENTRY_AREA_ARRAY_SIZE	(CPU_ENTRY_AREA_SIZE * NR_CPUS)
+
+/* Total size includes the readonly IDT mapping page as well: */
+#define CPU_ENTRY_AREA_TOTAL_SIZE	(CPU_ENTRY_AREA_ARRAY_SIZE + PAGE_SIZE)
+
+DECLARE_PER_CPU(struct cpu_entry_area *, cpu_entry_area);
+DECLARE_PER_CPU(struct cea_exception_stacks *, cea_exception_stacks);
+
+extern void setup_cpu_entry_areas(void);
+extern void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags);
+
+extern struct cpu_entry_area *get_cpu_entry_area(int cpu);
+
+static __always_inline struct entry_stack *cpu_entry_stack(int cpu)
+{
+	return &get_cpu_entry_area(cpu)->entry_stack_page.stack;
+}
+
+#define __this_cpu_ist_top_va(name)					\
+	CEA_ESTACK_TOP(__this_cpu_read(cea_exception_stacks), name)
+
+#define __this_cpu_ist_bottom_va(name)					\
+	CEA_ESTACK_BOT(__this_cpu_read(cea_exception_stacks), name)
+
+#endif