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
  14extern int num_pkey;
  15extern u32 reserved_allocation_mask; /* bits set for reserved keys */
  16
  17#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
  18                            VM_PKEY_BIT3 | VM_PKEY_BIT4)
  19
  20/* Override any generic PKEY permission defines */
  21#define PKEY_DISABLE_EXECUTE   0x4
  22#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS | \
  23                                PKEY_DISABLE_WRITE  | \
  24                                PKEY_DISABLE_EXECUTE)
  25
  26#ifdef CONFIG_PPC_BOOK3S_64
  27#include <asm/book3s/64/pkeys.h>
  28#else
  29#error "Not supported"
  30#endif
  31
  32
  33static inline u64 pkey_to_vmflag_bits(u16 pkey)
  34{
  35        return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
  36}
  37
  38static inline int vma_pkey(struct vm_area_struct *vma)
  39{
  40        if (!mmu_has_feature(MMU_FTR_PKEY))
  41                return 0;
  42        return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
  43}
  44
  45static inline int arch_max_pkey(void)
  46{
  47        return num_pkey;
  48}
  49
  50#define pkey_alloc_mask(pkey) (0x1 << pkey)
  51
  52#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
  53
  54#define __mm_pkey_allocated(mm, pkey) { \
  55        mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
  56}
  57
  58#define __mm_pkey_free(mm, pkey) {      \
  59        mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey);   \
  60}
  61
  62#define __mm_pkey_is_allocated(mm, pkey)        \
  63        (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
  64
  65#define __mm_pkey_is_reserved(pkey) (reserved_allocation_mask & \
  66                                       pkey_alloc_mask(pkey))
  67
  68static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
  69{
  70        if (pkey < 0 || pkey >= arch_max_pkey())
  71                return false;
  72
  73        /* Reserved keys are never allocated. */
  74        if (__mm_pkey_is_reserved(pkey))
  75                return false;
  76
  77        return __mm_pkey_is_allocated(mm, pkey);
  78}
  79
  80/*
  81 * Returns a positive, 5-bit key on success, or -1 on failure.
  82 * Relies on the mmap_lock to protect against concurrency in mm_pkey_alloc() and
  83 * mm_pkey_free().
  84 */
  85static inline int mm_pkey_alloc(struct mm_struct *mm)
  86{
  87        /*
  88         * Note: this is the one and only place we make sure that the pkey is
  89         * valid as far as the hardware is concerned. The rest of the kernel
  90         * trusts that only good, valid pkeys come out of here.
  91         */
  92        u32 all_pkeys_mask = (u32)(~(0x0));
  93        int ret;
  94
  95        if (!mmu_has_feature(MMU_FTR_PKEY))
  96                return -1;
  97        /*
  98         * Are we out of pkeys? We must handle this specially because ffz()
  99         * behavior is undefined if there are no zeros.
 100         */
 101        if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
 102                return -1;
 103
 104        ret = ffz((u32)mm_pkey_allocation_map(mm));
 105        __mm_pkey_allocated(mm, ret);
 106
 107        return ret;
 108}
 109
 110static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
 111{
 112        if (!mmu_has_feature(MMU_FTR_PKEY))
 113                return -1;
 114
 115        if (!mm_pkey_is_allocated(mm, pkey))
 116                return -EINVAL;
 117
 118        __mm_pkey_free(mm, pkey);
 119
 120        return 0;
 121}
 122
 123/*
 124 * Try to dedicate one of the protection keys to be used as an
 125 * execute-only protection key.
 126 */
 127extern int execute_only_pkey(struct mm_struct *mm);
 128extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
 129                                         int prot, int pkey);
 130static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
 131                                              int prot, int pkey)
 132{
 133        if (!mmu_has_feature(MMU_FTR_PKEY))
 134                return 0;
 135
 136        /*
 137         * Is this an mprotect_pkey() call? If so, never override the value that
 138         * came from the user.
 139         */
 140        if (pkey != -1)
 141                return pkey;
 142
 143        return __arch_override_mprotect_pkey(vma, prot, pkey);
 144}
 145
 146extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 147                                       unsigned long init_val);
 148static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 149                                            unsigned long init_val)
 150{
 151        if (!mmu_has_feature(MMU_FTR_PKEY))
 152                return -EINVAL;
 153
 154        /*
 155         * userspace should not change pkey-0 permissions.
 156         * pkey-0 is associated with every page in the kernel.
 157         * If userspace denies any permission on pkey-0, the
 158         * kernel cannot operate.
 159         */
 160        if (pkey == 0)
 161                return init_val ? -EINVAL : 0;
 162
 163        return __arch_set_user_pkey_access(tsk, pkey, init_val);
 164}
 165
 166static inline bool arch_pkeys_enabled(void)
 167{
 168        return mmu_has_feature(MMU_FTR_PKEY);
 169}
 170
 171extern void pkey_mm_init(struct mm_struct *mm);
 172#endif /*_ASM_POWERPC_KEYS_H */
 173