1 files changed, 28 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 075539f5f1c8..760c62f8e22f 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -11,7 +11,9 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/bitfield.h>
+#include <linux/kasan-enabled.h>
 #include <linux/page-flags.h>
+#include <linux/sched.h>
 #include <linux/types.h>
 
 #include <asm/pgtable-types.h>
@@ -40,11 +42,14 @@ void mte_sync_tags(pte_t old_pte, pte_t pte);
 void mte_copy_page_tags(void *kto, const void *kfrom);
 void mte_thread_init_user(void);
 void mte_thread_switch(struct task_struct *next);
+void mte_cpu_setup(void);
 void mte_suspend_enter(void);
+void mte_suspend_exit(void);
 long set_mte_ctrl(struct task_struct *task, unsigned long arg);
 long get_mte_ctrl(struct task_struct *task);
 int mte_ptrace_copy_tags(struct task_struct *child, long request,
 			 unsigned long addr, unsigned long data);
+size_t mte_probe_user_range(const char __user *uaddr, size_t size);
 
 #else /* CONFIG_ARM64_MTE */
 
@@ -69,6 +74,9 @@ static inline void mte_thread_switch(struct task_struct *next)
 static inline void mte_suspend_enter(void)
 {
 }
+static inline void mte_suspend_exit(void)
+{
+}
 static inline long set_mte_ctrl(struct task_struct *task, unsigned long arg)
 {
 	return 0;
@@ -86,6 +94,26 @@ static inline int mte_ptrace_copy_tags(struct task_struct *child,
 
 #endif /* CONFIG_ARM64_MTE */
 
+static inline void mte_disable_tco_entry(struct task_struct *task)
+{
+	if (!system_supports_mte())
+		return;
+
+	/*
+	 * Re-enable tag checking (TCO set on exception entry). This is only
+	 * necessary if MTE is enabled in either the kernel or the userspace
+	 * task in synchronous or asymmetric mode (SCTLR_EL1.TCF0 bit 0 is set
+	 * for both). With MTE disabled in the kernel and disabled or
+	 * asynchronous in userspace, tag check faults (including in uaccesses)
+	 * are not reported, therefore there is no need to re-enable checking.
+	 * This is beneficial on microarchitectures where re-enabling TCO is
+	 * expensive.
+	 */
+	if (kasan_hw_tags_enabled() ||
+	    (task->thread.sctlr_user & (1UL << SCTLR_EL1_TCF0_SHIFT)))
+		asm volatile(SET_PSTATE_TCO(0));
+}
+
 #ifdef CONFIG_KASAN_HW_TAGS
 /* Whether the MTE asynchronous mode is enabled. */
 DECLARE_STATIC_KEY_FALSE(mte_async_or_asymm_mode);