1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_PKEYS_H 3 #define _ASM_X86_PKEYS_H 4 5 /* 6 * If more than 16 keys are ever supported, a thorough audit 7 * will be necessary to ensure that the types that store key 8 * numbers and masks have sufficient capacity. 9 */ 10 #define arch_max_pkey() (cpu_feature_enabled(X86_FEATURE_OSPKE) ? 16 : 1) 11 12 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 13 unsigned long init_val); 14 15 static inline bool arch_pkeys_enabled(void) 16 { 17 return cpu_feature_enabled(X86_FEATURE_OSPKE); 18 } 19 20 /* 21 * Try to dedicate one of the protection keys to be used as an 22 * execute-only protection key. 23 */ 24 extern int __execute_only_pkey(struct mm_struct *mm); 25 static inline int execute_only_pkey(struct mm_struct *mm) 26 { 27 if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) 28 return ARCH_DEFAULT_PKEY; 29 30 return __execute_only_pkey(mm); 31 } 32 33 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma, 34 int prot, int pkey); 35 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, 36 int prot, int pkey) 37 { 38 if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) 39 return 0; 40 41 return __arch_override_mprotect_pkey(vma, prot, pkey); 42 } 43 44 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 45 unsigned long init_val); 46 47 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3) 48 49 #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map) 50 #define mm_set_pkey_allocated(mm, pkey) do { \ 51 mm_pkey_allocation_map(mm) |= (1U << pkey); \ 52 } while (0) 53 #define mm_set_pkey_free(mm, pkey) do { \ 54 mm_pkey_allocation_map(mm) &= ~(1U << pkey); \ 55 } while (0) 56 57 static inline 58 bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) 59 { 60 /* 61 * "Allocated" pkeys are those that have been returned 62 * from pkey_alloc() or pkey 0 which is allocated 63 * implicitly when the mm is created. 64 */ 65 if (pkey < 0) 66 return false; 67 if (pkey >= arch_max_pkey()) 68 return false; 69 /* 70 * The exec-only pkey is set in the allocation map, but 71 * is not available to any of the user interfaces like 72 * mprotect_pkey(). 73 */ 74 if (pkey == mm->context.execute_only_pkey) 75 return false; 76 77 return mm_pkey_allocation_map(mm) & (1U << pkey); 78 } 79 80 /* 81 * Returns a positive, 4-bit key on success, or -1 on failure. 82 */ 83 static inline 84 int mm_pkey_alloc(struct mm_struct *mm) 85 { 86 /* 87 * Note: this is the one and only place we make sure 88 * that the pkey is valid as far as the hardware is 89 * concerned. The rest of the kernel trusts that 90 * only good, valid pkeys come out of here. 91 */ 92 u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1); 93 int ret; 94 95 /* 96 * Are we out of pkeys? We must handle this specially 97 * because ffz() behavior is undefined if there are no 98 * zeros. 99 */ 100 if (mm_pkey_allocation_map(mm) == all_pkeys_mask) 101 return -1; 102 103 ret = ffz(mm_pkey_allocation_map(mm)); 104 105 mm_set_pkey_allocated(mm, ret); 106 107 return ret; 108 } 109 110 static inline 111 int mm_pkey_free(struct mm_struct *mm, int pkey) 112 { 113 if (!mm_pkey_is_allocated(mm, pkey)) 114 return -EINVAL; 115 116 mm_set_pkey_free(mm, pkey); 117 118 return 0; 119 } 120 121 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 122 unsigned long init_val); 123 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 124 unsigned long init_val); 125 126 static inline int vma_pkey(struct vm_area_struct *vma) 127 { 128 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 | 129 VM_PKEY_BIT2 | VM_PKEY_BIT3; 130 131 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT; 132 } 133 134 #endif /*_ASM_X86_PKEYS_H */ 135