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