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 21void mte_clear_page_tags(void *addr); 22unsigned long mte_copy_tags_from_user(void *to, const void __user *from, 23 unsigned long n); 24unsigned long mte_copy_tags_to_user(void __user *to, void *from, 25 unsigned long n); 26int mte_save_tags(struct page *page); 27void mte_save_page_tags(const void *page_addr, void *tag_storage); 28void mte_restore_tags(swp_entry_t entry, struct page *page); 29void mte_restore_page_tags(void *page_addr, const void *tag_storage); 30void mte_invalidate_tags(int type, pgoff_t offset); 31void mte_invalidate_tags_area(int type); 32void *mte_allocate_tag_storage(void); 33void 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/* simple lock to avoid multiple threads tagging the same page */ 40#define PG_mte_lock PG_arch_3 41 42static inline void set_page_mte_tagged(struct page *page) 43{ 44 /* 45 * Ensure that the tags written prior to this function are visible 46 * before the page flags update. 47 */ 48 smp_wmb(); 49 set_bit(PG_mte_tagged, &page->flags); 50} 51 52static inline bool page_mte_tagged(struct page *page) 53{ 54 bool ret = test_bit(PG_mte_tagged, &page->flags); 55 56 /* 57 * If the page is tagged, ensure ordering with a likely subsequent 58 * read of the tags. 59 */ 60 if (ret) 61 smp_rmb(); 62 return ret; 63} 64 65/* 66 * Lock the page for tagging and return 'true' if the page can be tagged, 67 * 'false' if already tagged. PG_mte_tagged is never cleared and therefore the 68 * locking only happens once for page initialisation. 69 * 70 * The page MTE lock state: 71 * 72 * Locked: PG_mte_lock && !PG_mte_tagged 73 * Unlocked: !PG_mte_lock || PG_mte_tagged 74 * 75 * Acquire semantics only if the page is tagged (returning 'false'). 76 */ 77static inline bool try_page_mte_tagging(struct page *page) 78{ 79 if (!test_and_set_bit(PG_mte_lock, &page->flags)) 80 return true; 81 82 /* 83 * The tags are either being initialised or may have been initialised 84 * already. Check if the PG_mte_tagged flag has been set or wait 85 * otherwise. 86 */ 87 smp_cond_load_acquire(&page->flags, VAL & (1UL << PG_mte_tagged)); 88 89 return false; 90} 91 92void mte_zero_clear_page_tags(void *addr); 93void mte_sync_tags(pte_t pte, unsigned int nr_pages); 94void mte_copy_page_tags(void *kto, const void *kfrom); 95void mte_thread_init_user(void); 96void mte_thread_switch(struct task_struct *next); 97void mte_cpu_setup(void); 98void mte_suspend_enter(void); 99void mte_suspend_exit(void); 100long set_mte_ctrl(struct task_struct *task, unsigned long arg); 101long get_mte_ctrl(struct task_struct *task); 102int mte_ptrace_copy_tags(struct task_struct *child, long request, 103 unsigned long addr, unsigned long data); 104size_t mte_probe_user_range(const char __user *uaddr, size_t size); 105 106#else /* CONFIG_ARM64_MTE */ 107 108/* unused if !CONFIG_ARM64_MTE, silence the compiler */ 109#define PG_mte_tagged 0 110 111static inline void set_page_mte_tagged(struct page *page) 112{ 113} 114static inline bool page_mte_tagged(struct page *page) 115{ 116 return false; 117} 118static inline bool try_page_mte_tagging(struct page *page) 119{ 120 return false; 121} 122static inline void mte_zero_clear_page_tags(void *addr) 123{ 124} 125static inline void mte_sync_tags(pte_t pte, unsigned int nr_pages) 126{ 127} 128static inline void mte_copy_page_tags(void *kto, const void *kfrom) 129{ 130} 131static inline void mte_thread_init_user(void) 132{ 133} 134static inline void mte_thread_switch(struct task_struct *next) 135{ 136} 137static inline void mte_suspend_enter(void) 138{ 139} 140static inline void mte_suspend_exit(void) 141{ 142} 143static inline long set_mte_ctrl(struct task_struct *task, unsigned long arg) 144{ 145 return 0; 146} 147static inline long get_mte_ctrl(struct task_struct *task) 148{ 149 return 0; 150} 151static inline int mte_ptrace_copy_tags(struct task_struct *child, 152 long request, unsigned long addr, 153 unsigned long data) 154{ 155 return -EIO; 156} 157 158#endif /* CONFIG_ARM64_MTE */ 159 160static inline void mte_disable_tco_entry(struct task_struct *task) 161{ 162 if (!system_supports_mte()) 163 return; 164 165 /* 166 * Re-enable tag checking (TCO set on exception entry). This is only 167 * necessary if MTE is enabled in either the kernel or the userspace 168 * task in synchronous or asymmetric mode (SCTLR_EL1.TCF0 bit 0 is set 169 * for both). With MTE disabled in the kernel and disabled or 170 * asynchronous in userspace, tag check faults (including in uaccesses) 171 * are not reported, therefore there is no need to re-enable checking. 172 * This is beneficial on microarchitectures where re-enabling TCO is 173 * expensive. 174 */ 175 if (kasan_hw_tags_enabled() || 176 (task->thread.sctlr_user & (1UL << SCTLR_EL1_TCF0_SHIFT))) 177 asm volatile(SET_PSTATE_TCO(0)); 178} 179 180#ifdef CONFIG_KASAN_HW_TAGS 181void mte_check_tfsr_el1(void); 182 183static inline void mte_check_tfsr_entry(void) 184{ 185 if (!system_supports_mte()) 186 return; 187 188 mte_check_tfsr_el1(); 189} 190 191static inline void mte_check_tfsr_exit(void) 192{ 193 if (!system_supports_mte()) 194 return; 195 196 /* 197 * The asynchronous faults are sync'ed automatically with 198 * TFSR_EL1 on kernel entry but for exit an explicit dsb() 199 * is required. 200 */ 201 dsb(nsh); 202 isb(); 203 204 mte_check_tfsr_el1(); 205} 206#else 207static inline void mte_check_tfsr_el1(void) 208{ 209} 210static inline void mte_check_tfsr_entry(void) 211{ 212} 213static inline void mte_check_tfsr_exit(void) 214{ 215} 216#endif /* CONFIG_KASAN_HW_TAGS */ 217 218#endif /* __ASSEMBLY__ */ 219#endif /* __ASM_MTE_H */ 220