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 #include <linux/pkeys.h> 8 9 #include <trace/events/tlb.h> 10 11 #include <asm/pgalloc.h> 12 #include <asm/tlbflush.h> 13 #include <asm/paravirt.h> 14 #include <asm/mpx.h> 15 #ifndef CONFIG_PARAVIRT 16 static inline void paravirt_activate_mm(struct mm_struct *prev, 17 struct mm_struct *next) 18 { 19 } 20 #endif /* !CONFIG_PARAVIRT */ 21 22 #ifdef CONFIG_PERF_EVENTS 23 extern struct static_key rdpmc_always_available; 24 25 static inline void load_mm_cr4(struct mm_struct *mm) 26 { 27 if (static_key_false(&rdpmc_always_available) || 28 atomic_read(&mm->context.perf_rdpmc_allowed)) 29 cr4_set_bits(X86_CR4_PCE); 30 else 31 cr4_clear_bits(X86_CR4_PCE); 32 } 33 #else 34 static inline void load_mm_cr4(struct mm_struct *mm) {} 35 #endif 36 37 #ifdef CONFIG_MODIFY_LDT_SYSCALL 38 /* 39 * ldt_structs can be allocated, used, and freed, but they are never 40 * modified while live. 41 */ 42 struct ldt_struct { 43 /* 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. 48 */ 49 struct desc_struct *entries; 50 unsigned int size; 51 }; 52 53 /* 54 * Used for LDT copy/destruction. 55 */ 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, 60 struct mm_struct *mm) 61 { 62 return 0; 63 } 64 static inline void destroy_context_ldt(struct mm_struct *mm) {} 65 #endif 66 67 static inline void load_mm_ldt(struct mm_struct *mm) 68 { 69 #ifdef CONFIG_MODIFY_LDT_SYSCALL 70 struct ldt_struct *ldt; 71 72 /* lockless_dereference synchronizes with smp_store_release */ 73 ldt = lockless_dereference(mm->context.ldt); 74 75 /* 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 81 * any user code. 82 * 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 86 * that we can see. 87 */ 88 89 if (unlikely(ldt)) 90 set_ldt(ldt->entries, ldt->size); 91 else 92 clear_LDT(); 93 #else 94 clear_LDT(); 95 #endif 96 97 DEBUG_LOCKS_WARN_ON(preemptible()); 98 } 99 100 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 101 { 102 #ifdef CONFIG_SMP 103 if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) 104 this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY); 105 #endif 106 } 107 108 static inline int init_new_context(struct task_struct *tsk, 109 struct mm_struct *mm) 110 { 111 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS 112 if (cpu_feature_enabled(X86_FEATURE_OSPKE)) { 113 /* pkey 0 is the default and always allocated */ 114 mm->context.pkey_allocation_map = 0x1; 115 /* -1 means unallocated or invalid */ 116 mm->context.execute_only_pkey = -1; 117 } 118 #endif 119 init_new_context_ldt(tsk, mm); 120 121 return 0; 122 } 123 static inline void destroy_context(struct mm_struct *mm) 124 { 125 destroy_context_ldt(mm); 126 } 127 128 extern void switch_mm(struct mm_struct *prev, struct mm_struct *next, 129 struct task_struct *tsk); 130 131 extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, 132 struct task_struct *tsk); 133 #define switch_mm_irqs_off switch_mm_irqs_off 134 135 #define activate_mm(prev, next) \ 136 do { \ 137 paravirt_activate_mm((prev), (next)); \ 138 switch_mm((prev), (next), NULL); \ 139 } while (0); 140 141 #ifdef CONFIG_X86_32 142 #define deactivate_mm(tsk, mm) \ 143 do { \ 144 lazy_load_gs(0); \ 145 } while (0) 146 #else 147 #define deactivate_mm(tsk, mm) \ 148 do { \ 149 load_gs_index(0); \ 150 loadsegment(fs, 0); \ 151 } while (0) 152 #endif 153 154 static inline void arch_dup_mmap(struct mm_struct *oldmm, 155 struct mm_struct *mm) 156 { 157 paravirt_arch_dup_mmap(oldmm, mm); 158 } 159 160 static inline void arch_exit_mmap(struct mm_struct *mm) 161 { 162 paravirt_arch_exit_mmap(mm); 163 } 164 165 #ifdef CONFIG_X86_64 166 static inline bool is_64bit_mm(struct mm_struct *mm) 167 { 168 return !IS_ENABLED(CONFIG_IA32_EMULATION) || 169 !(mm->context.ia32_compat == TIF_IA32); 170 } 171 #else 172 static inline bool is_64bit_mm(struct mm_struct *mm) 173 { 174 return false; 175 } 176 #endif 177 178 static inline void arch_bprm_mm_init(struct mm_struct *mm, 179 struct vm_area_struct *vma) 180 { 181 mpx_mm_init(mm); 182 } 183 184 static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma, 185 unsigned long start, unsigned long end) 186 { 187 /* 188 * mpx_notify_unmap() goes and reads a rarely-hot 189 * cacheline in the mm_struct. That can be expensive 190 * enough to be seen in profiles. 191 * 192 * The mpx_notify_unmap() call and its contents have been 193 * observed to affect munmap() performance on hardware 194 * where MPX is not present. 195 * 196 * The unlikely() optimizes for the fast case: no MPX 197 * in the CPU, or no MPX use in the process. Even if 198 * we get this wrong (in the unlikely event that MPX 199 * is widely enabled on some system) the overhead of 200 * MPX itself (reading bounds tables) is expected to 201 * overwhelm the overhead of getting this unlikely() 202 * consistently wrong. 203 */ 204 if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX))) 205 mpx_notify_unmap(mm, vma, start, end); 206 } 207 208 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS 209 static inline int vma_pkey(struct vm_area_struct *vma) 210 { 211 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 | 212 VM_PKEY_BIT2 | VM_PKEY_BIT3; 213 214 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT; 215 } 216 #else 217 static inline int vma_pkey(struct vm_area_struct *vma) 218 { 219 return 0; 220 } 221 #endif 222 223 static inline bool __pkru_allows_pkey(u16 pkey, bool write) 224 { 225 u32 pkru = read_pkru(); 226 227 if (!__pkru_allows_read(pkru, pkey)) 228 return false; 229 if (write && !__pkru_allows_write(pkru, pkey)) 230 return false; 231 232 return true; 233 } 234 235 /* 236 * We only want to enforce protection keys on the current process 237 * because we effectively have no access to PKRU for other 238 * processes or any way to tell *which * PKRU in a threaded 239 * process we could use. 240 * 241 * So do not enforce things if the VMA is not from the current 242 * mm, or if we are in a kernel thread. 243 */ 244 static inline bool vma_is_foreign(struct vm_area_struct *vma) 245 { 246 if (!current->mm) 247 return true; 248 /* 249 * Should PKRU be enforced on the access to this VMA? If 250 * the VMA is from another process, then PKRU has no 251 * relevance and should not be enforced. 252 */ 253 if (current->mm != vma->vm_mm) 254 return true; 255 256 return false; 257 } 258 259 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, 260 bool write, bool execute, bool foreign) 261 { 262 /* pkeys never affect instruction fetches */ 263 if (execute) 264 return true; 265 /* allow access if the VMA is not one from this process */ 266 if (foreign || vma_is_foreign(vma)) 267 return true; 268 return __pkru_allows_pkey(vma_pkey(vma), write); 269 } 270 271 static inline bool arch_pte_access_permitted(pte_t pte, bool write) 272 { 273 return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write); 274 } 275 #endif /* _ASM_X86_MMU_CONTEXT_H */ 276