1 // SPDX-License-Identifier: GPL-2.0
3 #ifndef _ASM_X86_CPU_ENTRY_AREA_H
4 #define _ASM_X86_CPU_ENTRY_AREA_H
6 #include <linux/percpu-defs.h>
7 #include <asm/processor.h>
10 * cpu_entry_area is a percpu region that contains things needed by the CPU
11 * and early entry/exit code. Real types aren't used for all fields here
12 * to avoid circular header dependencies.
14 * Every field is a virtual alias of some other allocated backing store.
15 * There is no direct allocation of a struct cpu_entry_area.
17 struct cpu_entry_area {
21 * The GDT is just below entry_stack and thus serves (on x86_64) as
22 * a a read-only guard page.
24 struct entry_stack_page entry_stack_page;
27 * On x86_64, the TSS is mapped RO. On x86_32, it's mapped RW because
28 * we need task switches to work, and task switches write to the TSS.
30 struct tss_struct tss;
32 char entry_trampoline[PAGE_SIZE];
36 * Exception stacks used for IST entries.
38 * In the future, this should have a separate slot for each stack
39 * with guard pages between them.
41 char exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ];
45 #define CPU_ENTRY_AREA_SIZE (sizeof(struct cpu_entry_area))
46 #define CPU_ENTRY_AREA_PAGES (CPU_ENTRY_AREA_SIZE / PAGE_SIZE)
48 DECLARE_PER_CPU(struct cpu_entry_area *, cpu_entry_area);
50 extern void setup_cpu_entry_areas(void);