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 the initially allocated keys */ 17 extern u32 reserved_allocation_mask; /* bits set for reserved keys */ 18 19 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \ 20 VM_PKEY_BIT3 | VM_PKEY_BIT4) 21 22 /* Override any generic PKEY permission defines */ 23 #define PKEY_DISABLE_EXECUTE 0x4 24 #define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS | \ 25 PKEY_DISABLE_WRITE | \ 26 PKEY_DISABLE_EXECUTE) 27 28 static inline u64 pkey_to_vmflag_bits(u16 pkey) 29 { 30 return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS); 31 } 32 33 static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags) 34 { 35 if (static_branch_likely(&pkey_disabled)) 36 return 0x0UL; 37 38 return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT4 : 0x0UL) | 39 ((vm_flags & VM_PKEY_BIT1) ? H_PTE_PKEY_BIT3 : 0x0UL) | 40 ((vm_flags & VM_PKEY_BIT2) ? H_PTE_PKEY_BIT2 : 0x0UL) | 41 ((vm_flags & VM_PKEY_BIT3) ? H_PTE_PKEY_BIT1 : 0x0UL) | 42 ((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT0 : 0x0UL)); 43 } 44 45 static inline int vma_pkey(struct vm_area_struct *vma) 46 { 47 if (static_branch_likely(&pkey_disabled)) 48 return 0; 49 return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; 50 } 51 52 #define arch_max_pkey() pkeys_total 53 54 static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) 55 { 56 return (((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) | 57 ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) | 58 ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) | 59 ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) | 60 ((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL)); 61 } 62 63 static inline u16 pte_to_pkey_bits(u64 pteflags) 64 { 65 return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) | 66 ((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) | 67 ((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) | 68 ((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) | 69 ((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL)); 70 } 71 72 #define pkey_alloc_mask(pkey) (0x1 << pkey) 73 74 #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map) 75 76 #define __mm_pkey_allocated(mm, pkey) { \ 77 mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \ 78 } 79 80 #define __mm_pkey_free(mm, pkey) { \ 81 mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey); \ 82 } 83 84 #define __mm_pkey_is_allocated(mm, pkey) \ 85 (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey)) 86 87 #define __mm_pkey_is_reserved(pkey) (reserved_allocation_mask & \ 88 pkey_alloc_mask(pkey)) 89 90 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) 91 { 92 if (pkey < 0 || pkey >= arch_max_pkey()) 93 return false; 94 95 /* Reserved keys are never allocated. */ 96 if (__mm_pkey_is_reserved(pkey)) 97 return false; 98 99 return __mm_pkey_is_allocated(mm, pkey); 100 } 101 102 /* 103 * Returns a positive, 5-bit key on success, or -1 on failure. 104 * Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and 105 * mm_pkey_free(). 106 */ 107 static inline int mm_pkey_alloc(struct mm_struct *mm) 108 { 109 /* 110 * Note: this is the one and only place we make sure that the pkey is 111 * valid as far as the hardware is concerned. The rest of the kernel 112 * trusts that only good, valid pkeys come out of here. 113 */ 114 u32 all_pkeys_mask = (u32)(~(0x0)); 115 int ret; 116 117 if (static_branch_likely(&pkey_disabled)) 118 return -1; 119 120 /* 121 * Are we out of pkeys? We must handle this specially because ffz() 122 * behavior is undefined if there are no zeros. 123 */ 124 if (mm_pkey_allocation_map(mm) == all_pkeys_mask) 125 return -1; 126 127 ret = ffz((u32)mm_pkey_allocation_map(mm)); 128 __mm_pkey_allocated(mm, ret); 129 130 return ret; 131 } 132 133 static inline int mm_pkey_free(struct mm_struct *mm, int pkey) 134 { 135 if (static_branch_likely(&pkey_disabled)) 136 return -1; 137 138 if (!mm_pkey_is_allocated(mm, pkey)) 139 return -EINVAL; 140 141 __mm_pkey_free(mm, pkey); 142 143 return 0; 144 } 145 146 /* 147 * Try to dedicate one of the protection keys to be used as an 148 * execute-only protection key. 149 */ 150 extern int __execute_only_pkey(struct mm_struct *mm); 151 static inline int execute_only_pkey(struct mm_struct *mm) 152 { 153 if (static_branch_likely(&pkey_disabled)) 154 return -1; 155 156 return __execute_only_pkey(mm); 157 } 158 159 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma, 160 int prot, int pkey); 161 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, 162 int prot, int pkey) 163 { 164 if (static_branch_likely(&pkey_disabled)) 165 return 0; 166 167 /* 168 * Is this an mprotect_pkey() call? If so, never override the value that 169 * came from the user. 170 */ 171 if (pkey != -1) 172 return pkey; 173 174 return __arch_override_mprotect_pkey(vma, prot, pkey); 175 } 176 177 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 178 unsigned long init_val); 179 static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 180 unsigned long init_val) 181 { 182 if (static_branch_likely(&pkey_disabled)) 183 return -EINVAL; 184 185 /* 186 * userspace should not change pkey-0 permissions. 187 * pkey-0 is associated with every page in the kernel. 188 * If userspace denies any permission on pkey-0, the 189 * kernel cannot operate. 190 */ 191 if (pkey == 0) 192 return init_val ? -EINVAL : 0; 193 194 return __arch_set_user_pkey_access(tsk, pkey, init_val); 195 } 196 197 static inline bool arch_pkeys_enabled(void) 198 { 199 return !static_branch_likely(&pkey_disabled); 200 } 201 202 extern void pkey_mm_init(struct mm_struct *mm); 203 extern bool arch_supports_pkeys(int cap); 204 extern unsigned int arch_usable_pkeys(void); 205 extern void thread_pkey_regs_save(struct thread_struct *thread); 206 extern void thread_pkey_regs_restore(struct thread_struct *new_thread, 207 struct thread_struct *old_thread); 208 extern void thread_pkey_regs_init(struct thread_struct *thread); 209 #endif /*_ASM_POWERPC_KEYS_H */ 210