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/*
  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
  40static inline u64 pkey_to_vmflag_bits(u16 pkey)
  41{
  42        return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
  43}
  44
  45static 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
  57static 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
  66static 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
  75static 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
 102static 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
 110extern void __arch_activate_pkey(int pkey);
 111extern 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 */
 117static 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
 148static 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 */
 169extern int __execute_only_pkey(struct mm_struct *mm);
 170static 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
 178extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
 179                                         int prot, int pkey);
 180static 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
 196extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 197                                       unsigned long init_val);
 198static 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
 206static inline bool arch_pkeys_enabled(void)
 207{
 208        return !static_branch_likely(&pkey_disabled);
 209}
 210
 211extern void pkey_mm_init(struct mm_struct *mm);
 212extern bool arch_supports_pkeys(int cap);
 213extern unsigned int arch_usable_pkeys(void);
 214extern void thread_pkey_regs_save(struct thread_struct *thread);
 215extern void thread_pkey_regs_restore(struct thread_struct *new_thread,
 216                                     struct thread_struct *old_thread);
 217extern void thread_pkey_regs_init(struct thread_struct *thread);
 218#endif /*_ASM_POWERPC_KEYS_H */
 219