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