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
152