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