1 #ifndef _ASM_X86_MMU_CONTEXT_H
2 #define _ASM_X86_MMU_CONTEXT_H
5 #include <linux/atomic.h>
6 #include <linux/mm_types.h>
7 #include <linux/pkeys.h>
9 #include <trace/events/tlb.h>
11 #include <asm/pgalloc.h>
12 #include <asm/tlbflush.h>
13 #include <asm/paravirt.h>
15 #ifndef CONFIG_PARAVIRT
16 static inline void paravirt_activate_mm(struct mm_struct *prev,
17 struct mm_struct *next)
20 #endif /* !CONFIG_PARAVIRT */
22 #ifdef CONFIG_PERF_EVENTS
23 extern struct static_key rdpmc_always_available;
25 static inline void load_mm_cr4(struct mm_struct *mm)
27 if (static_key_false(&rdpmc_always_available) ||
28 atomic_read(&mm->context.perf_rdpmc_allowed))
29 cr4_set_bits(X86_CR4_PCE);
31 cr4_clear_bits(X86_CR4_PCE);
34 static inline void load_mm_cr4(struct mm_struct *mm) {}
37 #ifdef CONFIG_MODIFY_LDT_SYSCALL
39 * ldt_structs can be allocated, used, and freed, but they are never
40 * modified while live.
44 * Xen requires page-aligned LDTs with special permissions. This is
45 * needed to prevent us from installing evil descriptors such as
46 * call gates. On native, we could merge the ldt_struct and LDT
47 * allocations, but it's not worth trying to optimize.
49 struct desc_struct *entries;
50 unsigned int nr_entries;
54 * Used for LDT copy/destruction.
56 int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm);
57 void destroy_context_ldt(struct mm_struct *mm);
58 #else /* CONFIG_MODIFY_LDT_SYSCALL */
59 static inline int init_new_context_ldt(struct task_struct *tsk,
64 static inline void destroy_context_ldt(struct mm_struct *mm) {}
67 static inline void load_mm_ldt(struct mm_struct *mm)
69 #ifdef CONFIG_MODIFY_LDT_SYSCALL
70 struct ldt_struct *ldt;
72 /* lockless_dereference synchronizes with smp_store_release */
73 ldt = lockless_dereference(mm->context.ldt);
76 * Any change to mm->context.ldt is followed by an IPI to all
77 * CPUs with the mm active. The LDT will not be freed until
78 * after the IPI is handled by all such CPUs. This means that,
79 * if the ldt_struct changes before we return, the values we see
80 * will be safe, and the new values will be loaded before we run
83 * NB: don't try to convert this to use RCU without extreme care.
84 * We would still need IRQs off, because we don't want to change
85 * the local LDT after an IPI loaded a newer value than the one
90 set_ldt(ldt->entries, ldt->nr_entries);
98 static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
100 #ifdef CONFIG_MODIFY_LDT_SYSCALL
102 * Load the LDT if either the old or new mm had an LDT.
104 * An mm will never go from having an LDT to not having an LDT. Two
105 * mms never share an LDT, so we don't gain anything by checking to
106 * see whether the LDT changed. There's also no guarantee that
107 * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
108 * then prev->context.ldt will also be non-NULL.
110 * If we really cared, we could optimize the case where prev == next
111 * and we're exiting lazy mode. Most of the time, if this happens,
112 * we don't actually need to reload LDTR, but modify_ldt() is mostly
113 * used by legacy code and emulators where we don't need this level of
116 * This uses | instead of || because it generates better code.
118 if (unlikely((unsigned long)prev->context.ldt |
119 (unsigned long)next->context.ldt))
123 DEBUG_LOCKS_WARN_ON(preemptible());
126 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
128 if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
129 this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
132 static inline int init_new_context(struct task_struct *tsk,
133 struct mm_struct *mm)
135 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
136 if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
137 /* pkey 0 is the default and always allocated */
138 mm->context.pkey_allocation_map = 0x1;
139 /* -1 means unallocated or invalid */
140 mm->context.execute_only_pkey = -1;
143 return init_new_context_ldt(tsk, mm);
145 static inline void destroy_context(struct mm_struct *mm)
147 destroy_context_ldt(mm);
150 extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
151 struct task_struct *tsk);
153 extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
154 struct task_struct *tsk);
155 #define switch_mm_irqs_off switch_mm_irqs_off
157 #define activate_mm(prev, next) \
159 paravirt_activate_mm((prev), (next)); \
160 switch_mm((prev), (next), NULL); \
164 #define deactivate_mm(tsk, mm) \
169 #define deactivate_mm(tsk, mm) \
172 loadsegment(fs, 0); \
176 static inline void arch_dup_mmap(struct mm_struct *oldmm,
177 struct mm_struct *mm)
179 paravirt_arch_dup_mmap(oldmm, mm);
182 static inline void arch_exit_mmap(struct mm_struct *mm)
184 paravirt_arch_exit_mmap(mm);
188 static inline bool is_64bit_mm(struct mm_struct *mm)
190 return !IS_ENABLED(CONFIG_IA32_EMULATION) ||
191 !(mm->context.ia32_compat == TIF_IA32);
194 static inline bool is_64bit_mm(struct mm_struct *mm)
200 static inline void arch_bprm_mm_init(struct mm_struct *mm,
201 struct vm_area_struct *vma)
206 static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
207 unsigned long start, unsigned long end)
210 * mpx_notify_unmap() goes and reads a rarely-hot
211 * cacheline in the mm_struct. That can be expensive
212 * enough to be seen in profiles.
214 * The mpx_notify_unmap() call and its contents have been
215 * observed to affect munmap() performance on hardware
216 * where MPX is not present.
218 * The unlikely() optimizes for the fast case: no MPX
219 * in the CPU, or no MPX use in the process. Even if
220 * we get this wrong (in the unlikely event that MPX
221 * is widely enabled on some system) the overhead of
222 * MPX itself (reading bounds tables) is expected to
223 * overwhelm the overhead of getting this unlikely()
224 * consistently wrong.
226 if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
227 mpx_notify_unmap(mm, vma, start, end);
230 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
231 static inline int vma_pkey(struct vm_area_struct *vma)
233 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
234 VM_PKEY_BIT2 | VM_PKEY_BIT3;
236 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
239 static inline int vma_pkey(struct vm_area_struct *vma)
246 * We only want to enforce protection keys on the current process
247 * because we effectively have no access to PKRU for other
248 * processes or any way to tell *which * PKRU in a threaded
249 * process we could use.
251 * So do not enforce things if the VMA is not from the current
252 * mm, or if we are in a kernel thread.
254 static inline bool vma_is_foreign(struct vm_area_struct *vma)
259 * Should PKRU be enforced on the access to this VMA? If
260 * the VMA is from another process, then PKRU has no
261 * relevance and should not be enforced.
263 if (current->mm != vma->vm_mm)
269 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
270 bool write, bool execute, bool foreign)
272 /* pkeys never affect instruction fetches */
275 /* allow access if the VMA is not one from this process */
276 if (foreign || vma_is_foreign(vma))
278 return __pkru_allows_pkey(vma_pkey(vma), write);
283 * This can be used from process context to figure out what the value of
284 * CR3 is without needing to do a (slow) __read_cr3().
286 * It's intended to be used for code like KVM that sneakily changes CR3
287 * and needs to restore it. It needs to be used very carefully.
289 static inline unsigned long __get_current_cr3_fast(void)
291 unsigned long cr3 = __pa(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd);
293 /* For now, be very restrictive about when this can be called. */
294 VM_WARN_ON(in_nmi() || preemptible());
296 VM_BUG_ON(cr3 != __read_cr3());
300 #endif /* _ASM_X86_MMU_CONTEXT_H */