1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2020 ARM Ltd. 4 */ 5 #ifndef __ASM_MTE_H 6 #define __ASM_MTE_H 7 8 #include <asm/compiler.h> 9 #include <asm/mte-def.h> 10 11 #ifndef __ASSEMBLY__ 12 13 #include <linux/bitfield.h> 14 #include <linux/kasan-enabled.h> 15 #include <linux/page-flags.h> 16 #include <linux/sched.h> 17 #include <linux/types.h> 18 19 #include <asm/pgtable-types.h> 20 21 void mte_clear_page_tags(void *addr); 22 unsigned long mte_copy_tags_from_user(void *to, const void __user *from, 23 unsigned long n); 24 unsigned long mte_copy_tags_to_user(void __user *to, void *from, 25 unsigned long n); 26 int mte_save_tags(struct page *page); 27 void mte_save_page_tags(const void *page_addr, void *tag_storage); 28 bool mte_restore_tags(swp_entry_t entry, struct page *page); 29 void mte_restore_page_tags(void *page_addr, const void *tag_storage); 30 void mte_invalidate_tags(int type, pgoff_t offset); 31 void mte_invalidate_tags_area(int type); 32 void *mte_allocate_tag_storage(void); 33 void mte_free_tag_storage(char *storage); 34 35 #ifdef CONFIG_ARM64_MTE 36 37 /* track which pages have valid allocation tags */ 38 #define PG_mte_tagged PG_arch_2 39 40 void mte_zero_clear_page_tags(void *addr); 41 void mte_sync_tags(pte_t old_pte, pte_t pte); 42 void mte_copy_page_tags(void *kto, const void *kfrom); 43 void mte_thread_init_user(void); 44 void mte_thread_switch(struct task_struct *next); 45 void mte_suspend_enter(void); 46 long set_mte_ctrl(struct task_struct *task, unsigned long arg); 47 long get_mte_ctrl(struct task_struct *task); 48 int mte_ptrace_copy_tags(struct task_struct *child, long request, 49 unsigned long addr, unsigned long data); 50 51 #else /* CONFIG_ARM64_MTE */ 52 53 /* unused if !CONFIG_ARM64_MTE, silence the compiler */ 54 #define PG_mte_tagged 0 55 56 static inline void mte_zero_clear_page_tags(void *addr) 57 { 58 } 59 static inline void mte_sync_tags(pte_t old_pte, pte_t pte) 60 { 61 } 62 static inline void mte_copy_page_tags(void *kto, const void *kfrom) 63 { 64 } 65 static inline void mte_thread_init_user(void) 66 { 67 } 68 static inline void mte_thread_switch(struct task_struct *next) 69 { 70 } 71 static inline void mte_suspend_enter(void) 72 { 73 } 74 static inline long set_mte_ctrl(struct task_struct *task, unsigned long arg) 75 { 76 return 0; 77 } 78 static inline long get_mte_ctrl(struct task_struct *task) 79 { 80 return 0; 81 } 82 static inline int mte_ptrace_copy_tags(struct task_struct *child, 83 long request, unsigned long addr, 84 unsigned long data) 85 { 86 return -EIO; 87 } 88 89 #endif /* CONFIG_ARM64_MTE */ 90 91 static inline void mte_disable_tco_entry(struct task_struct *task) 92 { 93 if (!system_supports_mte()) 94 return; 95 96 /* 97 * Re-enable tag checking (TCO set on exception entry). This is only 98 * necessary if MTE is enabled in either the kernel or the userspace 99 * task in synchronous or asymmetric mode (SCTLR_EL1.TCF0 bit 0 is set 100 * for both). With MTE disabled in the kernel and disabled or 101 * asynchronous in userspace, tag check faults (including in uaccesses) 102 * are not reported, therefore there is no need to re-enable checking. 103 * This is beneficial on microarchitectures where re-enabling TCO is 104 * expensive. 105 */ 106 if (kasan_hw_tags_enabled() || 107 (task->thread.sctlr_user & (1UL << SCTLR_EL1_TCF0_SHIFT))) 108 asm volatile(SET_PSTATE_TCO(0)); 109 } 110 111 #ifdef CONFIG_KASAN_HW_TAGS 112 /* Whether the MTE asynchronous mode is enabled. */ 113 DECLARE_STATIC_KEY_FALSE(mte_async_or_asymm_mode); 114 115 static inline bool system_uses_mte_async_or_asymm_mode(void) 116 { 117 return static_branch_unlikely(&mte_async_or_asymm_mode); 118 } 119 120 void mte_check_tfsr_el1(void); 121 122 static inline void mte_check_tfsr_entry(void) 123 { 124 if (!system_supports_mte()) 125 return; 126 127 mte_check_tfsr_el1(); 128 } 129 130 static inline void mte_check_tfsr_exit(void) 131 { 132 if (!system_supports_mte()) 133 return; 134 135 /* 136 * The asynchronous faults are sync'ed automatically with 137 * TFSR_EL1 on kernel entry but for exit an explicit dsb() 138 * is required. 139 */ 140 dsb(nsh); 141 isb(); 142 143 mte_check_tfsr_el1(); 144 } 145 #else 146 static inline bool system_uses_mte_async_or_asymm_mode(void) 147 { 148 return false; 149 } 150 static inline void mte_check_tfsr_el1(void) 151 { 152 } 153 static inline void mte_check_tfsr_entry(void) 154 { 155 } 156 static inline void mte_check_tfsr_exit(void) 157 { 158 } 159 #endif /* CONFIG_KASAN_HW_TAGS */ 160 161 #endif /* __ASSEMBLY__ */ 162 #endif /* __ASM_MTE_H */ 163