1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2023 Arm Ltd. 4 * 5 * Based on arch/x86/include/asm/pkeys.h 6 */ 7 8 #ifndef _ASM_ARM64_PKEYS_H 9 #define _ASM_ARM64_PKEYS_H 10 11 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2) 12 13 #define arch_max_pkey() 8 14 15 int arch_set_user_pkey_access(int pkey, unsigned long init_val); 16 17 static inline bool arch_pkeys_enabled(void) 18 { 19 return system_supports_poe(); 20 } 21 22 static inline int vma_pkey(struct vm_area_struct *vma) 23 { 24 return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; 25 } 26 27 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, 28 int prot, int pkey) 29 { 30 if (pkey != -1) 31 return pkey; 32 33 return vma_pkey(vma); 34 } 35 36 static inline int execute_only_pkey(struct mm_struct *mm) 37 { 38 // Execute-only mappings are handled by EPAN/FEAT_PAN3. 39 return -1; 40 } 41 42 #define mm_pkey_allocation_map(mm) (mm)->context.pkey_allocation_map 43 #define mm_set_pkey_allocated(mm, pkey) do { \ 44 mm_pkey_allocation_map(mm) |= (1U << pkey); \ 45 } while (0) 46 #define mm_set_pkey_free(mm, pkey) do { \ 47 mm_pkey_allocation_map(mm) &= ~(1U << pkey); \ 48 } while (0) 49 50 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) 51 { 52 /* 53 * "Allocated" pkeys are those that have been returned 54 * from pkey_alloc() or pkey 0 which is allocated 55 * implicitly when the mm is created. 56 */ 57 if (pkey < 0 || pkey >= arch_max_pkey()) 58 return false; 59 60 return mm_pkey_allocation_map(mm) & (1U << pkey); 61 } 62 63 /* 64 * Returns a positive, 3-bit key on success, or -1 on failure. 65 */ 66 static inline int mm_pkey_alloc(struct mm_struct *mm) 67 { 68 /* 69 * Note: this is the one and only place we make sure 70 * that the pkey is valid as far as the hardware is 71 * concerned. The rest of the kernel trusts that 72 * only good, valid pkeys come out of here. 73 */ 74 u8 all_pkeys_mask = GENMASK(arch_max_pkey() - 1, 0); 75 int ret; 76 77 if (!arch_pkeys_enabled()) 78 return -1; 79 80 /* 81 * Are we out of pkeys? We must handle this specially 82 * because ffz() behavior is undefined if there are no 83 * zeros. 84 */ 85 if (mm_pkey_allocation_map(mm) == all_pkeys_mask) 86 return -1; 87 88 ret = ffz(mm_pkey_allocation_map(mm)); 89 90 mm_set_pkey_allocated(mm, ret); 91 92 return ret; 93 } 94 95 static inline int mm_pkey_free(struct mm_struct *mm, int pkey) 96 { 97 if (!mm_pkey_is_allocated(mm, pkey)) 98 return -EINVAL; 99 100 mm_set_pkey_free(mm, pkey); 101 102 return 0; 103 } 104 105 #endif /* _ASM_ARM64_PKEYS_H */ 106