LXR linux/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
  14DECLARE_STATIC_KEY_TRUE(pkey_disabled);
  15extern int pkeys_total; /* total pkeys as per device tree */
  16extern u32 initial_allocation_mask; /* bits set for reserved keys */
  17
  18#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
  19                            VM_PKEY_BIT3 | VM_PKEY_BIT4)
  20
  21/* Override any generic PKEY permission defines */
  22#define PKEY_DISABLE_EXECUTE   0x4
  23#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS | \
  24                                PKEY_DISABLE_WRITE  | \
  25                                PKEY_DISABLE_EXECUTE)
  26
  27static inline u64 pkey_to_vmflag_bits(u16 pkey)
  28{
  29        return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
  30}
  31
  32static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
  33{
  34        if (static_branch_likely(&pkey_disabled))
  35                return 0x0UL;
  36
  37        return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT4 : 0x0UL) |
  38                ((vm_flags & VM_PKEY_BIT1) ? H_PTE_PKEY_BIT3 : 0x0UL) |
  39                ((vm_flags & VM_PKEY_BIT2) ? H_PTE_PKEY_BIT2 : 0x0UL) |
  40                ((vm_flags & VM_PKEY_BIT3) ? H_PTE_PKEY_BIT1 : 0x0UL) |
  41                ((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT0 : 0x0UL));
  42}
  43
  44static inline int vma_pkey(struct vm_area_struct *vma)
  45{
  46        if (static_branch_likely(&pkey_disabled))
  47                return 0;
  48        return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
  49}
  50
  51#define arch_max_pkey() pkeys_total
  52
  53static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
  54{
  55        return (((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) |
  56                ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) |
  57                ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) |
  58                ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) |
  59                ((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
  60}
  61
  62static inline u16 pte_to_pkey_bits(u64 pteflags)
  63{
  64        return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) |
  65                ((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) |
  66                ((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) |
  67                ((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) |
  68                ((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL));
  69}
  70
  71#define pkey_alloc_mask(pkey) (0x1 << pkey)
  72
  73#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
  74
  75#define __mm_pkey_allocated(mm, pkey) { \
  76        mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
  77}
  78
  79#define __mm_pkey_free(mm, pkey) {      \
  80        mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey);   \
  81}
  82
  83#define __mm_pkey_is_allocated(mm, pkey)        \
  84        (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
  85
  86#define __mm_pkey_is_reserved(pkey) (initial_allocation_mask & \
  87                                       pkey_alloc_mask(pkey))
  88
  89static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
  90{
  91        /* A reserved key is never considered as 'explicitly allocated' */
  92        return ((pkey < arch_max_pkey()) &&
  93                !__mm_pkey_is_reserved(pkey) &&
  94                __mm_pkey_is_allocated(mm, pkey));
  95}
  96
  97extern void __arch_activate_pkey(int pkey);
  98extern void __arch_deactivate_pkey(int pkey);
  99/*
 100 * Returns a positive, 5-bit key on success, or -1 on failure.
 101 * Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and
 102 * mm_pkey_free().
 103 */
 104static inline int mm_pkey_alloc(struct mm_struct *mm)
 105{
 106        /*
 107         * Note: this is the one and only place we make sure that the pkey is
 108         * valid as far as the hardware is concerned. The rest of the kernel
 109         * trusts that only good, valid pkeys come out of here.
 110         */
 111        u32 all_pkeys_mask = (u32)(~(0x0));
 112        int ret;
 113
 114        if (static_branch_likely(&pkey_disabled))
 115                return -1;
 116
 117        /*
 118         * Are we out of pkeys? We must handle this specially because ffz()
 119         * behavior is undefined if there are no zeros.
 120         */
 121        if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
 122                return -1;
 123
 124        ret = ffz((u32)mm_pkey_allocation_map(mm));
 125        __mm_pkey_allocated(mm, ret);
 126
 127        /*
 128         * Enable the key in the hardware
 129         */
 130        if (ret > 0)
 131                __arch_activate_pkey(ret);
 132        return ret;
 133}
 134
 135static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
 136{
 137        if (static_branch_likely(&pkey_disabled))
 138                return -1;
 139
 140        if (!mm_pkey_is_allocated(mm, pkey))
 141                return -EINVAL;
 142
 143        /*
 144         * Disable the key in the hardware
 145         */
 146        __arch_deactivate_pkey(pkey);
 147        __mm_pkey_free(mm, pkey);
 148
 149        return 0;
 150}
 151
 152/*
 153 * Try to dedicate one of the protection keys to be used as an
 154 * execute-only protection key.
 155 */
 156extern int __execute_only_pkey(struct mm_struct *mm);
 157static inline int execute_only_pkey(struct mm_struct *mm)
 158{
 159        if (static_branch_likely(&pkey_disabled))
 160                return -1;
 161
 162        return __execute_only_pkey(mm);
 163}
 164
 165extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
 166                                         int prot, int pkey);
 167static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
 168                                              int prot, int pkey)
 169{
 170        if (static_branch_likely(&pkey_disabled))
 171                return 0;
 172
 173        /*
 174         * Is this an mprotect_pkey() call? If so, never override the value that
 175         * came from the user.
 176         */
 177        if (pkey != -1)
 178                return pkey;
 179
 180        return __arch_override_mprotect_pkey(vma, prot, pkey);
 181}
 182
 183extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 184                                       unsigned long init_val);
 185static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 186                                            unsigned long init_val)
 187{
 188        if (static_branch_likely(&pkey_disabled))
 189                return -EINVAL;
 190        return __arch_set_user_pkey_access(tsk, pkey, init_val);
 191}
 192
 193static inline bool arch_pkeys_enabled(void)
 194{
 195        return !static_branch_likely(&pkey_disabled);
 196}
 197
 198extern void pkey_mm_init(struct mm_struct *mm);
 199extern bool arch_supports_pkeys(int cap);
 200extern unsigned int arch_usable_pkeys(void);
 201extern void thread_pkey_regs_save(struct thread_struct *thread);
 202extern void thread_pkey_regs_restore(struct thread_struct *new_thread,
 203                                     struct thread_struct *old_thread);
 204extern void thread_pkey_regs_init(struct thread_struct *thread);
 205#endif /*_ASM_POWERPC_KEYS_H */
 206