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 14 DECLARE_STATIC_KEY_TRUE(pkey_disabled); 15 extern int pkeys_total; /* total pkeys as per device tree */ 16 extern u32 initial_allocation_mask; /* bits set for reserved keys */ 17 18 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \ 19 VM_PKEY_BIT3 | VM_PKEY_BIT4) 20 21 /* Override any generic PKEY permission defines */ 22 #define PKEY_DISABLE_EXECUTE 0x4 23 #define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS | \ 24 PKEY_DISABLE_WRITE | \ 25 PKEY_DISABLE_EXECUTE) 26 27 static inline u64 pkey_to_vmflag_bits(u16 pkey) 28 { 29 return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS); 30 } 31 32 static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags) 33 { 34 if (static_branch_likely(&pkey_disabled)) 35 return 0x0UL; 36 37 return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT4 : 0x0UL) | 38 ((vm_flags & VM_PKEY_BIT1) ? H_PTE_PKEY_BIT3 : 0x0UL) | 39 ((vm_flags & VM_PKEY_BIT2) ? H_PTE_PKEY_BIT2 : 0x0UL) | 40 ((vm_flags & VM_PKEY_BIT3) ? H_PTE_PKEY_BIT1 : 0x0UL) | 41 ((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT0 : 0x0UL)); 42 } 43 44 static inline int vma_pkey(struct vm_area_struct *vma) 45 { 46 if (static_branch_likely(&pkey_disabled)) 47 return 0; 48 return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; 49 } 50 51 #define arch_max_pkey() pkeys_total 52 53 static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) 54 { 55 return (((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) | 56 ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) | 57 ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) | 58 ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) | 59 ((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL)); 60 } 61 62 static inline u16 pte_to_pkey_bits(u64 pteflags) 63 { 64 return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) | 65 ((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) | 66 ((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) | 67 ((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) | 68 ((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL)); 69 } 70 71 #define pkey_alloc_mask(pkey) (0x1 << pkey) 72 73 #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map) 74 75 #define __mm_pkey_allocated(mm, pkey) { \ 76 mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \ 77 } 78 79 #define __mm_pkey_free(mm, pkey) { \ 80 mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey); \ 81 } 82 83 #define __mm_pkey_is_allocated(mm, pkey) \ 84 (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey)) 85 86 #define __mm_pkey_is_reserved(pkey) (initial_allocation_mask & \ 87 pkey_alloc_mask(pkey)) 88 89 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) 90 { 91 /* A reserved key is never considered as 'explicitly allocated' */ 92 return ((pkey < arch_max_pkey()) && 93 !__mm_pkey_is_reserved(pkey) && 94 __mm_pkey_is_allocated(mm, pkey)); 95 } 96 97 extern void __arch_activate_pkey(int pkey); 98 extern void __arch_deactivate_pkey(int pkey); 99 /* 100 * Returns a positive, 5-bit key on success, or -1 on failure. 101 * Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and 102 * mm_pkey_free(). 103 */ 104 static inline int mm_pkey_alloc(struct mm_struct *mm) 105 { 106 /* 107 * Note: this is the one and only place we make sure that the pkey is 108 * valid as far as the hardware is concerned. The rest of the kernel 109 * trusts that only good, valid pkeys come out of here. 110 */ 111 u32 all_pkeys_mask = (u32)(~(0x0)); 112 int ret; 113 114 if (static_branch_likely(&pkey_disabled)) 115 return -1; 116 117 /* 118 * Are we out of pkeys? We must handle this specially because ffz() 119 * behavior is undefined if there are no zeros. 120 */ 121 if (mm_pkey_allocation_map(mm) == all_pkeys_mask) 122 return -1; 123 124 ret = ffz((u32)mm_pkey_allocation_map(mm)); 125 __mm_pkey_allocated(mm, ret); 126 127 /* 128 * Enable the key in the hardware 129 */ 130 if (ret > 0) 131 __arch_activate_pkey(ret); 132 return ret; 133 } 134 135 static inline int mm_pkey_free(struct mm_struct *mm, int pkey) 136 { 137 if (static_branch_likely(&pkey_disabled)) 138 return -1; 139 140 if (!mm_pkey_is_allocated(mm, pkey)) 141 return -EINVAL; 142 143 /* 144 * Disable the key in the hardware 145 */ 146 __arch_deactivate_pkey(pkey); 147 __mm_pkey_free(mm, pkey); 148 149 return 0; 150 } 151 152 /* 153 * Try to dedicate one of the protection keys to be used as an 154 * execute-only protection key. 155 */ 156 extern int __execute_only_pkey(struct mm_struct *mm); 157 static inline int execute_only_pkey(struct mm_struct *mm) 158 { 159 if (static_branch_likely(&pkey_disabled)) 160 return -1; 161 162 return __execute_only_pkey(mm); 163 } 164 165 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma, 166 int prot, int pkey); 167 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, 168 int prot, int pkey) 169 { 170 if (static_branch_likely(&pkey_disabled)) 171 return 0; 172 173 /* 174 * Is this an mprotect_pkey() call? If so, never override the value that 175 * came from the user. 176 */ 177 if (pkey != -1) 178 return pkey; 179 180 return __arch_override_mprotect_pkey(vma, prot, pkey); 181 } 182 183 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 184 unsigned long init_val); 185 static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 186 unsigned long init_val) 187 { 188 if (static_branch_likely(&pkey_disabled)) 189 return -EINVAL; 190 return __arch_set_user_pkey_access(tsk, pkey, init_val); 191 } 192 193 static inline bool arch_pkeys_enabled(void) 194 { 195 return !static_branch_likely(&pkey_disabled); 196 } 197 198 extern void pkey_mm_init(struct mm_struct *mm); 199 extern bool arch_supports_pkeys(int cap); 200 extern unsigned int arch_usable_pkeys(void); 201 extern void thread_pkey_regs_save(struct thread_struct *thread); 202 extern void thread_pkey_regs_restore(struct thread_struct *new_thread, 203 struct thread_struct *old_thread); 204 extern void thread_pkey_regs_init(struct thread_struct *thread); 205 #endif /*_ASM_POWERPC_KEYS_H */ 206