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