1 #ifndef _ASM_X86_MMU_CONTEXT_H 2 #define _ASM_X86_MMU_CONTEXT_H 3 4 #include <asm/desc.h> 5 #include <linux/atomic.h> 6 #include <linux/mm_types.h> 7 8 #include <trace/events/tlb.h> 9 10 #include <asm/pgalloc.h> 11 #include <asm/tlbflush.h> 12 #include <asm/paravirt.h> 13 #include <asm/mpx.h> 14 #ifndef CONFIG_PARAVIRT 15 static inline void paravirt_activate_mm(struct mm_struct *prev, 16 struct mm_struct *next) 17 { 18 } 19 #endif /* !CONFIG_PARAVIRT */ 20 21 #ifdef CONFIG_PERF_EVENTS 22 extern struct static_key rdpmc_always_available; 23 24 static inline void load_mm_cr4(struct mm_struct *mm) 25 { 26 if (static_key_false(&rdpmc_always_available) || 27 atomic_read(&mm->context.perf_rdpmc_allowed)) 28 cr4_set_bits(X86_CR4_PCE); 29 else 30 cr4_clear_bits(X86_CR4_PCE); 31 } 32 #else 33 static inline void load_mm_cr4(struct mm_struct *mm) {} 34 #endif 35 36 #ifdef CONFIG_MODIFY_LDT_SYSCALL 37 /* 38 * ldt_structs can be allocated, used, and freed, but they are never 39 * modified while live. 40 */ 41 struct ldt_struct { 42 /* 43 * Xen requires page-aligned LDTs with special permissions. This is 44 * needed to prevent us from installing evil descriptors such as 45 * call gates. On native, we could merge the ldt_struct and LDT 46 * allocations, but it's not worth trying to optimize. 47 */ 48 struct desc_struct *entries; 49 int size; 50 }; 51 52 /* 53 * Used for LDT copy/destruction. 54 */ 55 int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm); 56 void destroy_context_ldt(struct mm_struct *mm); 57 #else /* CONFIG_MODIFY_LDT_SYSCALL */ 58 static inline int init_new_context_ldt(struct task_struct *tsk, 59 struct mm_struct *mm) 60 { 61 return 0; 62 } 63 static inline void destroy_context_ldt(struct mm_struct *mm) {} 64 #endif 65 66 static inline void load_mm_ldt(struct mm_struct *mm) 67 { 68 #ifdef CONFIG_MODIFY_LDT_SYSCALL 69 struct ldt_struct *ldt; 70 71 /* lockless_dereference synchronizes with smp_store_release */ 72 ldt = lockless_dereference(mm->context.ldt); 73 74 /* 75 * Any change to mm->context.ldt is followed by an IPI to all 76 * CPUs with the mm active. The LDT will not be freed until 77 * after the IPI is handled by all such CPUs. This means that, 78 * if the ldt_struct changes before we return, the values we see 79 * will be safe, and the new values will be loaded before we run 80 * any user code. 81 * 82 * NB: don't try to convert this to use RCU without extreme care. 83 * We would still need IRQs off, because we don't want to change 84 * the local LDT after an IPI loaded a newer value than the one 85 * that we can see. 86 */ 87 88 if (unlikely(ldt)) 89 set_ldt(ldt->entries, ldt->size); 90 else 91 clear_LDT(); 92 #else 93 clear_LDT(); 94 #endif 95 96 DEBUG_LOCKS_WARN_ON(preemptible()); 97 } 98 99 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 100 { 101 #ifdef CONFIG_SMP 102 if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) 103 this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY); 104 #endif 105 } 106 107 static inline int init_new_context(struct task_struct *tsk, 108 struct mm_struct *mm) 109 { 110 init_new_context_ldt(tsk, mm); 111 return 0; 112 } 113 static inline void destroy_context(struct mm_struct *mm) 114 { 115 destroy_context_ldt(mm); 116 } 117 118 extern void switch_mm(struct mm_struct *prev, struct mm_struct *next, 119 struct task_struct *tsk); 120 121 extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, 122 struct task_struct *tsk); 123 #define switch_mm_irqs_off switch_mm_irqs_off 124 125 #define activate_mm(prev, next) \ 126 do { \ 127 paravirt_activate_mm((prev), (next)); \ 128 switch_mm((prev), (next), NULL); \ 129 } while (0); 130 131 #ifdef CONFIG_X86_32 132 #define deactivate_mm(tsk, mm) \ 133 do { \ 134 lazy_load_gs(0); \ 135 } while (0) 136 #else 137 #define deactivate_mm(tsk, mm) \ 138 do { \ 139 load_gs_index(0); \ 140 loadsegment(fs, 0); \ 141 } while (0) 142 #endif 143 144 static inline void arch_dup_mmap(struct mm_struct *oldmm, 145 struct mm_struct *mm) 146 { 147 paravirt_arch_dup_mmap(oldmm, mm); 148 } 149 150 static inline void arch_exit_mmap(struct mm_struct *mm) 151 { 152 paravirt_arch_exit_mmap(mm); 153 } 154 155 #ifdef CONFIG_X86_64 156 static inline bool is_64bit_mm(struct mm_struct *mm) 157 { 158 return !config_enabled(CONFIG_IA32_EMULATION) || 159 !(mm->context.ia32_compat == TIF_IA32); 160 } 161 #else 162 static inline bool is_64bit_mm(struct mm_struct *mm) 163 { 164 return false; 165 } 166 #endif 167 168 static inline void arch_bprm_mm_init(struct mm_struct *mm, 169 struct vm_area_struct *vma) 170 { 171 mpx_mm_init(mm); 172 } 173 174 static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma, 175 unsigned long start, unsigned long end) 176 { 177 /* 178 * mpx_notify_unmap() goes and reads a rarely-hot 179 * cacheline in the mm_struct. That can be expensive 180 * enough to be seen in profiles. 181 * 182 * The mpx_notify_unmap() call and its contents have been 183 * observed to affect munmap() performance on hardware 184 * where MPX is not present. 185 * 186 * The unlikely() optimizes for the fast case: no MPX 187 * in the CPU, or no MPX use in the process. Even if 188 * we get this wrong (in the unlikely event that MPX 189 * is widely enabled on some system) the overhead of 190 * MPX itself (reading bounds tables) is expected to 191 * overwhelm the overhead of getting this unlikely() 192 * consistently wrong. 193 */ 194 if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX))) 195 mpx_notify_unmap(mm, vma, start, end); 196 } 197 198 static inline int vma_pkey(struct vm_area_struct *vma) 199 { 200 u16 pkey = 0; 201 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS 202 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 | 203 VM_PKEY_BIT2 | VM_PKEY_BIT3; 204 pkey = (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT; 205 #endif 206 return pkey; 207 } 208 209 static inline bool __pkru_allows_pkey(u16 pkey, bool write) 210 { 211 u32 pkru = read_pkru(); 212 213 if (!__pkru_allows_read(pkru, pkey)) 214 return false; 215 if (write && !__pkru_allows_write(pkru, pkey)) 216 return false; 217 218 return true; 219 } 220 221 /* 222 * We only want to enforce protection keys on the current process 223 * because we effectively have no access to PKRU for other 224 * processes or any way to tell *which * PKRU in a threaded 225 * process we could use. 226 * 227 * So do not enforce things if the VMA is not from the current 228 * mm, or if we are in a kernel thread. 229 */ 230 static inline bool vma_is_foreign(struct vm_area_struct *vma) 231 { 232 if (!current->mm) 233 return true; 234 /* 235 * Should PKRU be enforced on the access to this VMA? If 236 * the VMA is from another process, then PKRU has no 237 * relevance and should not be enforced. 238 */ 239 if (current->mm != vma->vm_mm) 240 return true; 241 242 return false; 243 } 244 245 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, 246 bool write, bool execute, bool foreign) 247 { 248 /* pkeys never affect instruction fetches */ 249 if (execute) 250 return true; 251 /* allow access if the VMA is not one from this process */ 252 if (foreign || vma_is_foreign(vma)) 253 return true; 254 return __pkru_allows_pkey(vma_pkey(vma), write); 255 } 256 257 static inline bool arch_pte_access_permitted(pte_t pte, bool write) 258 { 259 return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write); 260 } 261 262 #endif /* _ASM_X86_MMU_CONTEXT_H */ 263