1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_X86_MMU_CONTEXT_H
3#define _ASM_X86_MMU_CONTEXT_H
4
5#include <asm/desc.h>
6#include <linux/atomic.h>
7#include <linux/mm_types.h>
8#include <linux/pkeys.h>
9
10#include <trace/events/tlb.h>
11
12#include <asm/tlbflush.h>
13#include <asm/paravirt.h>
14#include <asm/debugreg.h>
15#include <asm/gsseg.h>
16
17extern atomic64_t last_mm_ctx_id;
18
19#ifdef CONFIG_PERF_EVENTS
20DECLARE_STATIC_KEY_FALSE(rdpmc_never_available_key);
21DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key);
22void cr4_update_pce(void *ignored);
23#endif
24
25#ifdef CONFIG_MODIFY_LDT_SYSCALL
26/*
27 * ldt_structs can be allocated, used, and freed, but they are never
28 * modified while live.
29 */
30struct ldt_struct {
31 /*
32 * Xen requires page-aligned LDTs with special permissions. This is
33 * needed to prevent us from installing evil descriptors such as
34 * call gates. On native, we could merge the ldt_struct and LDT
35 * allocations, but it's not worth trying to optimize.
36 */
37 struct desc_struct *entries;
38 unsigned int nr_entries;
39
40 /*
41 * If PTI is in use, then the entries array is not mapped while we're
42 * in user mode. The whole array will be aliased at the addressed
43 * given by ldt_slot_va(slot). We use two slots so that we can allocate
44 * and map, and enable a new LDT without invalidating the mapping
45 * of an older, still-in-use LDT.
46 *
47 * slot will be -1 if this LDT doesn't have an alias mapping.
48 */
49 int slot;
50};
51
52/*
53 * Used for LDT copy/destruction.
54 */
55static inline void init_new_context_ldt(struct mm_struct *mm)
56{
57 mm->context.ldt = NULL;
58 init_rwsem(&mm->context.ldt_usr_sem);
59}
60int ldt_dup_context(struct mm_struct *oldmm, struct mm_struct *mm);
61void destroy_context_ldt(struct mm_struct *mm);
62void ldt_arch_exit_mmap(struct mm_struct *mm);
63#else /* CONFIG_MODIFY_LDT_SYSCALL */
64static inline void init_new_context_ldt(struct mm_struct *mm) { }
65static inline int ldt_dup_context(struct mm_struct *oldmm,
66 struct mm_struct *mm)
67{
68 return 0;
69}
70static inline void destroy_context_ldt(struct mm_struct *mm) { }
71static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
72#endif
73
74#ifdef CONFIG_MODIFY_LDT_SYSCALL
75extern void load_mm_ldt(struct mm_struct *mm);
76extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next);
77#else
78static inline void load_mm_ldt(struct mm_struct *mm)
79{
80 clear_LDT();
81}
82static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
83{
84 DEBUG_LOCKS_WARN_ON(preemptible());
85}
86#endif
87
88#ifdef CONFIG_ADDRESS_MASKING
89static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm)
90{
91 return mm->context.lam_cr3_mask;
92}
93
94static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
95{
96 mm->context.lam_cr3_mask = oldmm->context.lam_cr3_mask;
97 mm->context.untag_mask = oldmm->context.untag_mask;
98}
99
100#define mm_untag_mask mm_untag_mask
101static inline unsigned long mm_untag_mask(struct mm_struct *mm)
102{
103 return mm->context.untag_mask;
104}
105
106static inline void mm_reset_untag_mask(struct mm_struct *mm)
107{
108 mm->context.untag_mask = -1UL;
109}
110
111#define arch_pgtable_dma_compat arch_pgtable_dma_compat
112static inline bool arch_pgtable_dma_compat(struct mm_struct *mm)
113{
114 return !mm_lam_cr3_mask(mm) ||
115 test_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &mm->context.flags);
116}
117#else
118
119static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm)
120{
121 return 0;
122}
123
124static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
125{
126}
127
128static inline void mm_reset_untag_mask(struct mm_struct *mm)
129{
130}
131#endif
132
133#define enter_lazy_tlb enter_lazy_tlb
134extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
135
136/*
137 * Init a new mm. Used on mm copies, like at fork()
138 * and on mm's that are brand-new, like at execve().
139 */
140#define init_new_context init_new_context
141static inline int init_new_context(struct task_struct *tsk,
142 struct mm_struct *mm)
143{
144 mutex_init(&mm->context.lock);
145
146 mm->context.ctx_id = atomic64_inc_return(v: &last_mm_ctx_id);
147 atomic64_set(v: &mm->context.tlb_gen, i: 0);
148
149#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
150 if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
151 /* pkey 0 is the default and allocated implicitly */
152 mm->context.pkey_allocation_map = 0x1;
153 /* -1 means unallocated or invalid */
154 mm->context.execute_only_pkey = -1;
155 }
156#endif
157 mm_reset_untag_mask(mm);
158 init_new_context_ldt(mm);
159 return 0;
160}
161
162#define destroy_context destroy_context
163static inline void destroy_context(struct mm_struct *mm)
164{
165 destroy_context_ldt(mm);
166}
167
168extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
169 struct task_struct *tsk);
170
171extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
172 struct task_struct *tsk);
173#define switch_mm_irqs_off switch_mm_irqs_off
174
175#define activate_mm(prev, next) \
176do { \
177 paravirt_enter_mmap(next); \
178 switch_mm((prev), (next), NULL); \
179} while (0);
180
181#ifdef CONFIG_X86_32
182#define deactivate_mm(tsk, mm) \
183do { \
184 loadsegment(gs, 0); \
185} while (0)
186#else
187#define deactivate_mm(tsk, mm) \
188do { \
189 shstk_free(tsk); \
190 load_gs_index(0); \
191 loadsegment(fs, 0); \
192} while (0)
193#endif
194
195static inline void arch_dup_pkeys(struct mm_struct *oldmm,
196 struct mm_struct *mm)
197{
198#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
199 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
200 return;
201
202 /* Duplicate the oldmm pkey state in mm: */
203 mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
204 mm->context.execute_only_pkey = oldmm->context.execute_only_pkey;
205#endif
206}
207
208static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
209{
210 arch_dup_pkeys(oldmm, mm);
211 paravirt_enter_mmap(next: mm);
212 dup_lam(oldmm, mm);
213 return ldt_dup_context(oldmm, mm);
214}
215
216static inline void arch_exit_mmap(struct mm_struct *mm)
217{
218 paravirt_arch_exit_mmap(mm);
219 ldt_arch_exit_mmap(mm);
220}
221
222#ifdef CONFIG_X86_64
223static inline bool is_64bit_mm(struct mm_struct *mm)
224{
225 return !IS_ENABLED(CONFIG_IA32_EMULATION) ||
226 !test_bit(MM_CONTEXT_UPROBE_IA32, &mm->context.flags);
227}
228#else
229static inline bool is_64bit_mm(struct mm_struct *mm)
230{
231 return false;
232}
233#endif
234
235static inline void arch_unmap(struct mm_struct *mm, unsigned long start,
236 unsigned long end)
237{
238}
239
240/*
241 * We only want to enforce protection keys on the current process
242 * because we effectively have no access to PKRU for other
243 * processes or any way to tell *which * PKRU in a threaded
244 * process we could use.
245 *
246 * So do not enforce things if the VMA is not from the current
247 * mm, or if we are in a kernel thread.
248 */
249static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
250 bool write, bool execute, bool foreign)
251{
252 /* pkeys never affect instruction fetches */
253 if (execute)
254 return true;
255 /* allow access if the VMA is not one from this process */
256 if (foreign || vma_is_foreign(vma))
257 return true;
258 return __pkru_allows_pkey(pkey: vma_pkey(vma), write);
259}
260
261unsigned long __get_current_cr3_fast(void);
262
263#include <asm-generic/mmu_context.h>
264
265#endif /* _ASM_X86_MMU_CONTEXT_H */
266

source code of linux/arch/x86/include/asm/mmu_context.h