arch/x86/include/asm/mmu_context.h

   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
  16 extern atomic64_t last_mm_ctx_id;
  17
  18 #ifndef CONFIG_PARAVIRT_XXL
  19 static inline void paravirt_activate_mm(struct mm_struct *prev,
  20                                         struct mm_struct *next)
  21 {
  22 }
  23 #endif  /* !CONFIG_PARAVIRT_XXL */
  24
  25 #ifdef CONFIG_PERF_EVENTS
  26 DECLARE_STATIC_KEY_FALSE(rdpmc_never_available_key);
  27 DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key);
  28 void cr4_update_pce(void *ignored);
  29 #endif
  30
  31 #ifdef CONFIG_MODIFY_LDT_SYSCALL
  32 /*
  33  * ldt_structs can be allocated, used, and freed, but they are never
  34  * modified while live.
  35  */
  36 struct ldt_struct {
  37         /*
  38          * Xen requires page-aligned LDTs with special permissions.  This is
  39          * needed to prevent us from installing evil descriptors such as
  40          * call gates.  On native, we could merge the ldt_struct and LDT
  41          * allocations, but it's not worth trying to optimize.
  42          */
  43         struct desc_struct      *entries;
  44         unsigned int            nr_entries;
  45
  46         /*
  47          * If PTI is in use, then the entries array is not mapped while we're
  48          * in user mode.  The whole array will be aliased at the addressed
  49          * given by ldt_slot_va(slot).  We use two slots so that we can allocate
  50          * and map, and enable a new LDT without invalidating the mapping
  51          * of an older, still-in-use LDT.
  52          *
  53          * slot will be -1 if this LDT doesn't have an alias mapping.
  54          */
  55         int                     slot;
  56 };
  57
  58 /*
  59  * Used for LDT copy/destruction.
  60  */
  61 static inline void init_new_context_ldt(struct mm_struct *mm)
  62 {
  63         mm->context.ldt = NULL;
  64         init_rwsem(&mm->context.ldt_usr_sem);
  65 }
  66 int ldt_dup_context(struct mm_struct *oldmm, struct mm_struct *mm);
  67 void destroy_context_ldt(struct mm_struct *mm);
  68 void ldt_arch_exit_mmap(struct mm_struct *mm);
  69 #else   /* CONFIG_MODIFY_LDT_SYSCALL */
  70 static inline void init_new_context_ldt(struct mm_struct *mm) { }
  71 static inline int ldt_dup_context(struct mm_struct *oldmm,
  72                                   struct mm_struct *mm)
  73 {
  74         return 0;
  75 }
  76 static inline void destroy_context_ldt(struct mm_struct *mm) { }
  77 static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
  78 #endif
  79
  80 #ifdef CONFIG_MODIFY_LDT_SYSCALL
  81 extern void load_mm_ldt(struct mm_struct *mm);
  82 extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next);
  83 #else
  84 static inline void load_mm_ldt(struct mm_struct *mm)
  85 {
  86         clear_LDT();
  87 }
  88 static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
  89 {
  90         DEBUG_LOCKS_WARN_ON(preemptible());
  91 }
  92 #endif
  93
  94 #define enter_lazy_tlb enter_lazy_tlb
  95 extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
  96
  97 /*
  98  * Init a new mm.  Used on mm copies, like at fork()
  99  * and on mm's that are brand-new, like at execve().
 100  */
 101 #define init_new_context init_new_context
 102 static inline int init_new_context(struct task_struct *tsk,
 103                                    struct mm_struct *mm)
 104 {
 105         mutex_init(&mm->context.lock);
 106
 107         mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
 108         atomic64_set(&mm->context.tlb_gen, 0);
 109
 110 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
 111         if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
 112                 /* pkey 0 is the default and allocated implicitly */
 113                 mm->context.pkey_allocation_map = 0x1;
 114                 /* -1 means unallocated or invalid */
 115                 mm->context.execute_only_pkey = -1;
 116         }
 117 #endif
 118         init_new_context_ldt(mm);
 119         return 0;
 120 }
 121
 122 #define destroy_context destroy_context
 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_pkeys(struct mm_struct *oldmm,
 155                                   struct mm_struct *mm)
 156 {
 157 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
 158         if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
 159                 return;
 160
 161         /* Duplicate the oldmm pkey state in mm: */
 162         mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
 163         mm->context.execute_only_pkey   = oldmm->context.execute_only_pkey;
 164 #endif
 165 }
 166
 167 static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
 168 {
 169         arch_dup_pkeys(oldmm, mm);
 170         paravirt_arch_dup_mmap(oldmm, mm);
 171         return ldt_dup_context(oldmm, mm);
 172 }
 173
 174 static inline void arch_exit_mmap(struct mm_struct *mm)
 175 {
 176         paravirt_arch_exit_mmap(mm);
 177         ldt_arch_exit_mmap(mm);
 178 }
 179
 180 #ifdef CONFIG_X86_64
 181 static inline bool is_64bit_mm(struct mm_struct *mm)
 182 {
 183         return  !IS_ENABLED(CONFIG_IA32_EMULATION) ||
 184                 !(mm->context.flags & MM_CONTEXT_UPROBE_IA32);
 185 }
 186 #else
 187 static inline bool is_64bit_mm(struct mm_struct *mm)
 188 {
 189         return false;
 190 }
 191 #endif
 192
 193 static inline void arch_unmap(struct mm_struct *mm, unsigned long start,
 194                               unsigned long end)
 195 {
 196 }
 197
 198 /*
 199  * We only want to enforce protection keys on the current process
 200  * because we effectively have no access to PKRU for other
 201  * processes or any way to tell *which * PKRU in a threaded
 202  * process we could use.
 203  *
 204  * So do not enforce things if the VMA is not from the current
 205  * mm, or if we are in a kernel thread.
 206  */
 207 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 208                 bool write, bool execute, bool foreign)
 209 {
 210         /* pkeys never affect instruction fetches */
 211         if (execute)
 212                 return true;
 213         /* allow access if the VMA is not one from this process */
 214         if (foreign || vma_is_foreign(vma))
 215                 return true;
 216         return __pkru_allows_pkey(vma_pkey(vma), write);
 217 }
 218
 219 unsigned long __get_current_cr3_fast(void);
 220
 221 #include <asm-generic/mmu_context.h>
 222
 223 #endif /* _ASM_X86_MMU_CONTEXT_H */