arch/x86/include/asm/cpu_entry_area.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 #ifndef _ASM_X86_CPU_ENTRY_AREA_H
   4 #define _ASM_X86_CPU_ENTRY_AREA_H
   5
   6 #include <linux/percpu-defs.h>
   7 #include <asm/processor.h>
   8 #include <asm/intel_ds.h>
   9 #include <asm/pgtable_areas.h>
  10
  11 #ifdef CONFIG_X86_64
  12
  13 /* Macro to enforce the same ordering and stack sizes */
  14 #define ESTACKS_MEMBERS(guardsize, optional_stack_size)         \
  15         char    DF_stack_guard[guardsize];                      \
  16         char    DF_stack[EXCEPTION_STKSZ];                      \
  17         char    NMI_stack_guard[guardsize];                     \
  18         char    NMI_stack[EXCEPTION_STKSZ];                     \
  19         char    DB_stack_guard[guardsize];                      \
  20         char    DB_stack[EXCEPTION_STKSZ];                      \
  21         char    MCE_stack_guard[guardsize];                     \
  22         char    MCE_stack[EXCEPTION_STKSZ];                     \
  23         char    VC_stack_guard[guardsize];                      \
  24         char    VC_stack[optional_stack_size];                  \
  25         char    VC2_stack_guard[guardsize];                     \
  26         char    VC2_stack[optional_stack_size];                 \
  27         char    IST_top_guard[guardsize];                       \
  28
  29 /* The exception stacks' physical storage. No guard pages required */
  30 struct exception_stacks {
  31         ESTACKS_MEMBERS(0, 0)
  32 };
  33
  34 /* The effective cpu entry area mapping with guard pages. */
  35 struct cea_exception_stacks {
  36         ESTACKS_MEMBERS(PAGE_SIZE, EXCEPTION_STKSZ)
  37 };
  38
  39 /*
  40  * The exception stack ordering in [cea_]exception_stacks
  41  */
  42 enum exception_stack_ordering {
  43         ESTACK_DF,
  44         ESTACK_NMI,
  45         ESTACK_DB,
  46         ESTACK_MCE,
  47         ESTACK_VC,
  48         ESTACK_VC2,
  49         N_EXCEPTION_STACKS
  50 };
  51
  52 #define CEA_ESTACK_SIZE(st)                                     \
  53         sizeof(((struct cea_exception_stacks *)0)->st## _stack)
  54
  55 #define CEA_ESTACK_BOT(ceastp, st)                              \
  56         ((unsigned long)&(ceastp)->st## _stack)
  57
  58 #define CEA_ESTACK_TOP(ceastp, st)                              \
  59         (CEA_ESTACK_BOT(ceastp, st) + CEA_ESTACK_SIZE(st))
  60
  61 #define CEA_ESTACK_OFFS(st)                                     \
  62         offsetof(struct cea_exception_stacks, st## _stack)
  63
  64 #define CEA_ESTACK_PAGES                                        \
  65         (sizeof(struct cea_exception_stacks) / PAGE_SIZE)
  66
  67 #endif
  68
  69 #ifdef CONFIG_X86_32
  70 struct doublefault_stack {
  71         unsigned long stack[(PAGE_SIZE - sizeof(struct x86_hw_tss)) / sizeof(unsigned long)];
  72         struct x86_hw_tss tss;
  73 } __aligned(PAGE_SIZE);
  74 #endif
  75
  76 /*
  77  * cpu_entry_area is a percpu region that contains things needed by the CPU
  78  * and early entry/exit code.  Real types aren't used for all fields here
  79  * to avoid circular header dependencies.
  80  *
  81  * Every field is a virtual alias of some other allocated backing store.
  82  * There is no direct allocation of a struct cpu_entry_area.
  83  */
  84 struct cpu_entry_area {
  85         char gdt[PAGE_SIZE];
  86
  87         /*
  88          * The GDT is just below entry_stack and thus serves (on x86_64) as
  89          * a read-only guard page. On 32-bit the GDT must be writeable, so
  90          * it needs an extra guard page.
  91          */
  92 #ifdef CONFIG_X86_32
  93         char guard_entry_stack[PAGE_SIZE];
  94 #endif
  95         struct entry_stack_page entry_stack_page;
  96
  97 #ifdef CONFIG_X86_32
  98         char guard_doublefault_stack[PAGE_SIZE];
  99         struct doublefault_stack doublefault_stack;
 100 #endif
 101
 102         /*
 103          * On x86_64, the TSS is mapped RO.  On x86_32, it's mapped RW because
 104          * we need task switches to work, and task switches write to the TSS.
 105          */
 106         struct tss_struct tss;
 107
 108 #ifdef CONFIG_X86_64
 109         /*
 110          * Exception stacks used for IST entries with guard pages.
 111          */
 112         struct cea_exception_stacks estacks;
 113 #endif
 114         /*
 115          * Per CPU debug store for Intel performance monitoring. Wastes a
 116          * full page at the moment.
 117          */
 118         struct debug_store cpu_debug_store;
 119         /*
 120          * The actual PEBS/BTS buffers must be mapped to user space
 121          * Reserve enough fixmap PTEs.
 122          */
 123         struct debug_store_buffers cpu_debug_buffers;
 124 };
 125
 126 #define CPU_ENTRY_AREA_SIZE             (sizeof(struct cpu_entry_area))
 127 #define CPU_ENTRY_AREA_ARRAY_SIZE       (CPU_ENTRY_AREA_SIZE * NR_CPUS)
 128
 129 /* Total size includes the readonly IDT mapping page as well: */
 130 #define CPU_ENTRY_AREA_TOTAL_SIZE       (CPU_ENTRY_AREA_ARRAY_SIZE + PAGE_SIZE)
 131
 132 DECLARE_PER_CPU(struct cpu_entry_area *, cpu_entry_area);
 133 DECLARE_PER_CPU(struct cea_exception_stacks *, cea_exception_stacks);
 134
 135 extern void setup_cpu_entry_areas(void);
 136 extern void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags);
 137
 138 extern struct cpu_entry_area *get_cpu_entry_area(int cpu);
 139
 140 static inline struct entry_stack *cpu_entry_stack(int cpu)
 141 {
 142         return &get_cpu_entry_area(cpu)->entry_stack_page.stack;
 143 }
 144
 145 #define __this_cpu_ist_top_va(name)                                     \
 146         CEA_ESTACK_TOP(__this_cpu_read(cea_exception_stacks), name)
 147
 148 #define __this_cpu_ist_bottom_va(name)                                  \
 149         CEA_ESTACK_BOT(__this_cpu_read(cea_exception_stacks), name)
 150
 151 #endif