arch/x86/include/asm/pkeys.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_PKEYS_H
   3 #define _ASM_X86_PKEYS_H
   4
   5 #define ARCH_DEFAULT_PKEY       0
   6
   7 /*
   8  * If more than 16 keys are ever supported, a thorough audit
   9  * will be necessary to ensure that the types that store key
  10  * numbers and masks have sufficient capacity.
  11  */
  12 #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
  13
  14 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
  15                 unsigned long init_val);
  16
  17 static inline bool arch_pkeys_enabled(void)
  18 {
  19         return boot_cpu_has(X86_FEATURE_OSPKE);
  20 }
  21
  22 /*
  23  * Try to dedicate one of the protection keys to be used as an
  24  * execute-only protection key.
  25  */
  26 extern int __execute_only_pkey(struct mm_struct *mm);
  27 static inline int execute_only_pkey(struct mm_struct *mm)
  28 {
  29         if (!boot_cpu_has(X86_FEATURE_OSPKE))
  30                 return ARCH_DEFAULT_PKEY;
  31
  32         return __execute_only_pkey(mm);
  33 }
  34
  35 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
  36                 int prot, int pkey);
  37 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
  38                 int prot, int pkey)
  39 {
  40         if (!boot_cpu_has(X86_FEATURE_OSPKE))
  41                 return 0;
  42
  43         return __arch_override_mprotect_pkey(vma, prot, pkey);
  44 }
  45
  46 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
  47                 unsigned long init_val);
  48
  49 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)
  50
  51 #define mm_pkey_allocation_map(mm)      (mm->context.pkey_allocation_map)
  52 #define mm_set_pkey_allocated(mm, pkey) do {            \
  53         mm_pkey_allocation_map(mm) |= (1U << pkey);     \
  54 } while (0)
  55 #define mm_set_pkey_free(mm, pkey) do {                 \
  56         mm_pkey_allocation_map(mm) &= ~(1U << pkey);    \
  57 } while (0)
  58
  59 static inline
  60 bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
  61 {
  62         /*
  63          * "Allocated" pkeys are those that have been returned
  64          * from pkey_alloc() or pkey 0 which is allocated
  65          * implicitly when the mm is created.
  66          */
  67         if (pkey < 0)
  68                 return false;
  69         if (pkey >= arch_max_pkey())
  70                 return false;
  71         /*
  72          * The exec-only pkey is set in the allocation map, but
  73          * is not available to any of the user interfaces like
  74          * mprotect_pkey().
  75          */
  76         if (pkey == mm->context.execute_only_pkey)
  77                 return false;
  78
  79         return mm_pkey_allocation_map(mm) & (1U << pkey);
  80 }
  81
  82 /*
  83  * Returns a positive, 4-bit key on success, or -1 on failure.
  84  */
  85 static inline
  86 int mm_pkey_alloc(struct mm_struct *mm)
  87 {
  88         /*
  89          * Note: this is the one and only place we make sure
  90          * that the pkey is valid as far as the hardware is
  91          * concerned.  The rest of the kernel trusts that
  92          * only good, valid pkeys come out of here.
  93          */
  94         u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
  95         int ret;
  96
  97         /*
  98          * Are we out of pkeys?  We must handle this specially
  99          * because ffz() behavior is undefined if there are no
 100          * zeros.
 101          */
 102         if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
 103                 return -1;
 104
 105         ret = ffz(mm_pkey_allocation_map(mm));
 106
 107         mm_set_pkey_allocated(mm, ret);
 108
 109         return ret;
 110 }
 111
 112 static inline
 113 int mm_pkey_free(struct mm_struct *mm, int pkey)
 114 {
 115         if (!mm_pkey_is_allocated(mm, pkey))
 116                 return -EINVAL;
 117
 118         mm_set_pkey_free(mm, pkey);
 119
 120         return 0;
 121 }
 122
 123 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 124                 unsigned long init_val);
 125 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 126                 unsigned long init_val);
 127 extern void copy_init_pkru_to_fpregs(void);
 128
 129 static inline int vma_pkey(struct vm_area_struct *vma)
 130 {
 131         unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
 132                                       VM_PKEY_BIT2 | VM_PKEY_BIT3;
 133
 134         return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
 135 }
 136
 137 #endif /*_ASM_X86_PKEYS_H */