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>
16 extern atomic64_t last_mm_ctx_id;
18 #ifndef CONFIG_PARAVIRT
19 static inline void paravirt_activate_mm(struct mm_struct *prev,
20 struct mm_struct *next)
23 #endif /* !CONFIG_PARAVIRT */
25 #ifdef CONFIG_PERF_EVENTS
26 extern struct static_key rdpmc_always_available;
28 static inline void load_mm_cr4(struct mm_struct *mm)
30 if (static_key_false(&rdpmc_always_available) ||
31 atomic_read(&mm->context.perf_rdpmc_allowed))
32 cr4_set_bits(X86_CR4_PCE);
34 cr4_clear_bits(X86_CR4_PCE);
37 static inline void load_mm_cr4(struct mm_struct *mm) {}
40 #ifdef CONFIG_MODIFY_LDT_SYSCALL
42 * ldt_structs can be allocated, used, and freed, but they are never
43 * modified while live.
47 * Xen requires page-aligned LDTs with special permissions. This is
48 * needed to prevent us from installing evil descriptors such as
49 * call gates. On native, we could merge the ldt_struct and LDT
50 * allocations, but it's not worth trying to optimize.
52 struct desc_struct *entries;
57 * Used for LDT copy/destruction.
59 int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm);
60 void destroy_context_ldt(struct mm_struct *mm);
61 #else /* CONFIG_MODIFY_LDT_SYSCALL */
62 static inline int init_new_context_ldt(struct task_struct *tsk,
67 static inline void destroy_context_ldt(struct mm_struct *mm) {}
70 static inline void load_mm_ldt(struct mm_struct *mm)
72 #ifdef CONFIG_MODIFY_LDT_SYSCALL
73 struct ldt_struct *ldt;
75 /* lockless_dereference synchronizes with smp_store_release */
76 ldt = lockless_dereference(mm->context.ldt);
79 * Any change to mm->context.ldt is followed by an IPI to all
80 * CPUs with the mm active. The LDT will not be freed until
81 * after the IPI is handled by all such CPUs. This means that,
82 * if the ldt_struct changes before we return, the values we see
83 * will be safe, and the new values will be loaded before we run
86 * NB: don't try to convert this to use RCU without extreme care.
87 * We would still need IRQs off, because we don't want to change
88 * the local LDT after an IPI loaded a newer value than the one
93 set_ldt(ldt->entries, ldt->size);
100 DEBUG_LOCKS_WARN_ON(preemptible());
103 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
105 if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
106 this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
109 static inline int init_new_context(struct task_struct *tsk,
110 struct mm_struct *mm)
112 mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
114 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
115 if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
116 /* pkey 0 is the default and allocated implicitly */
117 mm->context.pkey_allocation_map = 0x1;
118 /* -1 means unallocated or invalid */
119 mm->context.execute_only_pkey = -1;
122 return init_new_context_ldt(tsk, mm);
124 static inline void destroy_context(struct mm_struct *mm)
126 destroy_context_ldt(mm);
129 extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
130 struct task_struct *tsk);
132 extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
133 struct task_struct *tsk);
134 #define switch_mm_irqs_off switch_mm_irqs_off
136 #define activate_mm(prev, next) \
138 paravirt_activate_mm((prev), (next)); \
139 switch_mm((prev), (next), NULL); \
143 #define deactivate_mm(tsk, mm) \
148 #define deactivate_mm(tsk, mm) \
151 loadsegment(fs, 0); \
155 static inline void arch_dup_mmap(struct mm_struct *oldmm,
156 struct mm_struct *mm)
158 paravirt_arch_dup_mmap(oldmm, mm);
161 static inline void arch_exit_mmap(struct mm_struct *mm)
163 paravirt_arch_exit_mmap(mm);
167 static inline bool is_64bit_mm(struct mm_struct *mm)
169 return !IS_ENABLED(CONFIG_IA32_EMULATION) ||
170 !(mm->context.ia32_compat == TIF_IA32);
173 static inline bool is_64bit_mm(struct mm_struct *mm)
179 static inline void arch_bprm_mm_init(struct mm_struct *mm,
180 struct vm_area_struct *vma)
185 static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
186 unsigned long start, unsigned long end)
189 * mpx_notify_unmap() goes and reads a rarely-hot
190 * cacheline in the mm_struct. That can be expensive
191 * enough to be seen in profiles.
193 * The mpx_notify_unmap() call and its contents have been
194 * observed to affect munmap() performance on hardware
195 * where MPX is not present.
197 * The unlikely() optimizes for the fast case: no MPX
198 * in the CPU, or no MPX use in the process. Even if
199 * we get this wrong (in the unlikely event that MPX
200 * is widely enabled on some system) the overhead of
201 * MPX itself (reading bounds tables) is expected to
202 * overwhelm the overhead of getting this unlikely()
203 * consistently wrong.
205 if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
206 mpx_notify_unmap(mm, vma, start, end);
209 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
210 static inline int vma_pkey(struct vm_area_struct *vma)
212 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
213 VM_PKEY_BIT2 | VM_PKEY_BIT3;
215 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
218 static inline int vma_pkey(struct vm_area_struct *vma)
224 static inline bool __pkru_allows_pkey(u16 pkey, bool write)
226 u32 pkru = read_pkru();
228 if (!__pkru_allows_read(pkru, pkey))
230 if (write && !__pkru_allows_write(pkru, pkey))
237 * We only want to enforce protection keys on the current process
238 * because we effectively have no access to PKRU for other
239 * processes or any way to tell *which * PKRU in a threaded
240 * process we could use.
242 * So do not enforce things if the VMA is not from the current
243 * mm, or if we are in a kernel thread.
245 static inline bool vma_is_foreign(struct vm_area_struct *vma)
250 * Should PKRU be enforced on the access to this VMA? If
251 * the VMA is from another process, then PKRU has no
252 * relevance and should not be enforced.
254 if (current->mm != vma->vm_mm)
260 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
261 bool write, bool execute, bool foreign)
263 /* pkeys never affect instruction fetches */
266 /* allow access if the VMA is not one from this process */
267 if (foreign || vma_is_foreign(vma))
269 return __pkru_allows_pkey(vma_pkey(vma), write);
272 static inline bool arch_pte_access_permitted(pte_t pte, bool write)
274 return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write);
276 #endif /* _ASM_X86_MMU_CONTEXT_H */