arch/powerpc/include/asm/pkeys.h

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  * PowerPC Memory Protection Keys management
   4  *
   5  * Copyright 2017, Ram Pai, IBM Corporation.
   6  */
   7
   8 #ifndef _ASM_POWERPC_KEYS_H
   9 #define _ASM_POWERPC_KEYS_H
  10
  11 #include <linux/jump_label.h>
  12 #include <asm/firmware.h>
  13
  14 DECLARE_STATIC_KEY_TRUE(pkey_disabled);
  15 extern int pkeys_total; /* total pkeys as per device tree */
  16 extern u32 initial_allocation_mask; /* bits set for reserved keys */
  17
  18 /*
  19  * Define these here temporarily so we're not dependent on patching linux/mm.h.
  20  * Once it's updated we can drop these.
  21  */
  22 #ifndef VM_PKEY_BIT0
  23 # define VM_PKEY_SHIFT  VM_HIGH_ARCH_BIT_0
  24 # define VM_PKEY_BIT0   VM_HIGH_ARCH_0
  25 # define VM_PKEY_BIT1   VM_HIGH_ARCH_1
  26 # define VM_PKEY_BIT2   VM_HIGH_ARCH_2
  27 # define VM_PKEY_BIT3   VM_HIGH_ARCH_3
  28 # define VM_PKEY_BIT4   VM_HIGH_ARCH_4
  29 #endif
  30
  31 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
  32                             VM_PKEY_BIT3 | VM_PKEY_BIT4)
  33
  34 /* Override any generic PKEY permission defines */
  35 #define PKEY_DISABLE_EXECUTE   0x4
  36 #define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS | \
  37                                 PKEY_DISABLE_WRITE  | \
  38                                 PKEY_DISABLE_EXECUTE)
  39
  40 static inline u64 pkey_to_vmflag_bits(u16 pkey)
  41 {
  42         return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
  43 }
  44
  45 static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
  46 {
  47         if (static_branch_likely(&pkey_disabled))
  48                 return 0x0UL;
  49
  50         return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT4 : 0x0UL) |
  51                 ((vm_flags & VM_PKEY_BIT1) ? H_PTE_PKEY_BIT3 : 0x0UL) |
  52                 ((vm_flags & VM_PKEY_BIT2) ? H_PTE_PKEY_BIT2 : 0x0UL) |
  53                 ((vm_flags & VM_PKEY_BIT3) ? H_PTE_PKEY_BIT1 : 0x0UL) |
  54                 ((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT0 : 0x0UL));
  55 }
  56
  57 static inline int vma_pkey(struct vm_area_struct *vma)
  58 {
  59         if (static_branch_likely(&pkey_disabled))
  60                 return 0;
  61         return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
  62 }
  63
  64 #define arch_max_pkey() pkeys_total
  65
  66 static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
  67 {
  68         return (((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) |
  69                 ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) |
  70                 ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) |
  71                 ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) |
  72                 ((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
  73 }
  74
  75 static inline u16 pte_to_pkey_bits(u64 pteflags)
  76 {
  77         return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) |
  78                 ((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) |
  79                 ((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) |
  80                 ((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) |
  81                 ((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL));
  82 }
  83
  84 #define pkey_alloc_mask(pkey) (0x1 << pkey)
  85
  86 #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
  87
  88 #define __mm_pkey_allocated(mm, pkey) { \
  89         mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
  90 }
  91
  92 #define __mm_pkey_free(mm, pkey) {      \
  93         mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey);   \
  94 }
  95
  96 #define __mm_pkey_is_allocated(mm, pkey)        \
  97         (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
  98
  99 #define __mm_pkey_is_reserved(pkey) (initial_allocation_mask & \
 100                                        pkey_alloc_mask(pkey))
 101
 102 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
 103 {
 104         /* A reserved key is never considered as 'explicitly allocated' */
 105         return ((pkey < arch_max_pkey()) &&
 106                 !__mm_pkey_is_reserved(pkey) &&
 107                 __mm_pkey_is_allocated(mm, pkey));
 108 }
 109
 110 extern void __arch_activate_pkey(int pkey);
 111 extern void __arch_deactivate_pkey(int pkey);
 112 /*
 113  * Returns a positive, 5-bit key on success, or -1 on failure.
 114  * Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and
 115  * mm_pkey_free().
 116  */
 117 static inline int mm_pkey_alloc(struct mm_struct *mm)
 118 {
 119         /*
 120          * Note: this is the one and only place we make sure that the pkey is
 121          * valid as far as the hardware is concerned. The rest of the kernel
 122          * trusts that only good, valid pkeys come out of here.
 123          */
 124         u32 all_pkeys_mask = (u32)(~(0x0));
 125         int ret;
 126
 127         if (static_branch_likely(&pkey_disabled))
 128                 return -1;
 129
 130         /*
 131          * Are we out of pkeys? We must handle this specially because ffz()
 132          * behavior is undefined if there are no zeros.
 133          */
 134         if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
 135                 return -1;
 136
 137         ret = ffz((u32)mm_pkey_allocation_map(mm));
 138         __mm_pkey_allocated(mm, ret);
 139
 140         /*
 141          * Enable the key in the hardware
 142          */
 143         if (ret > 0)
 144                 __arch_activate_pkey(ret);
 145         return ret;
 146 }
 147
 148 static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
 149 {
 150         if (static_branch_likely(&pkey_disabled))
 151                 return -1;
 152
 153         if (!mm_pkey_is_allocated(mm, pkey))
 154                 return -EINVAL;
 155
 156         /*
 157          * Disable the key in the hardware
 158          */
 159         __arch_deactivate_pkey(pkey);
 160         __mm_pkey_free(mm, pkey);
 161
 162         return 0;
 163 }
 164
 165 /*
 166  * Try to dedicate one of the protection keys to be used as an
 167  * execute-only protection key.
 168  */
 169 extern int __execute_only_pkey(struct mm_struct *mm);
 170 static inline int execute_only_pkey(struct mm_struct *mm)
 171 {
 172         if (static_branch_likely(&pkey_disabled))
 173                 return -1;
 174
 175         return __execute_only_pkey(mm);
 176 }
 177
 178 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
 179                                          int prot, int pkey);
 180 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
 181                                               int prot, int pkey)
 182 {
 183         if (static_branch_likely(&pkey_disabled))
 184                 return 0;
 185
 186         /*
 187          * Is this an mprotect_pkey() call? If so, never override the value that
 188          * came from the user.
 189          */
 190         if (pkey != -1)
 191                 return pkey;
 192
 193         return __arch_override_mprotect_pkey(vma, prot, pkey);
 194 }
 195
 196 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 197                                        unsigned long init_val);
 198 static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 199                                             unsigned long init_val)
 200 {
 201         if (static_branch_likely(&pkey_disabled))
 202                 return -EINVAL;
 203         return __arch_set_user_pkey_access(tsk, pkey, init_val);
 204 }
 205
 206 static inline bool arch_pkeys_enabled(void)
 207 {
 208         return !static_branch_likely(&pkey_disabled);
 209 }
 210
 211 extern void pkey_mm_init(struct mm_struct *mm);
 212 extern bool arch_supports_pkeys(int cap);
 213 extern unsigned int arch_usable_pkeys(void);
 214 extern void thread_pkey_regs_save(struct thread_struct *thread);
 215 extern void thread_pkey_regs_restore(struct thread_struct *new_thread,
 216                                      struct thread_struct *old_thread);
 217 extern void thread_pkey_regs_init(struct thread_struct *thread);
 218 #endif /*_ASM_POWERPC_KEYS_H */