1 files changed, 137 insertions, 19 deletions

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 760c62f8e22f..6d4a78b9dc3e 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -8,7 +8,7 @@
 #include <asm/compiler.h>
 #include <asm/mte-def.h>
 
-#ifndef __ASSEMBLY__
+#ifndef __ASSEMBLER__
 
 #include <linux/bitfield.h>
 #include <linux/kasan-enabled.h>
@@ -25,7 +25,7 @@ unsigned long mte_copy_tags_to_user(void __user *to, void *from,
 				    unsigned long n);
 int mte_save_tags(struct page *page);
 void mte_save_page_tags(const void *page_addr, void *tag_storage);
-bool mte_restore_tags(swp_entry_t entry, struct page *page);
+void mte_restore_tags(swp_entry_t entry, struct page *page);
 void mte_restore_page_tags(void *page_addr, const void *tag_storage);
 void mte_invalidate_tags(int type, pgoff_t offset);
 void mte_invalidate_tags_area(int type);
@@ -36,9 +36,67 @@ void mte_free_tag_storage(char *storage);
 
 /* track which pages have valid allocation tags */
 #define PG_mte_tagged	PG_arch_2
+/* simple lock to avoid multiple threads tagging the same page */
+#define PG_mte_lock	PG_arch_3
+
+static inline void set_page_mte_tagged(struct page *page)
+{
+	VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));
+
+	/*
+	 * Ensure that the tags written prior to this function are visible
+	 * before the page flags update.
+	 */
+	smp_wmb();
+	set_bit(PG_mte_tagged, &page->flags.f);
+}
+
+static inline bool page_mte_tagged(struct page *page)
+{
+	bool ret = test_bit(PG_mte_tagged, &page->flags.f);
+
+	VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));
+
+	/*
+	 * If the page is tagged, ensure ordering with a likely subsequent
+	 * read of the tags.
+	 */
+	if (ret)
+		smp_rmb();
+	return ret;
+}
+
+/*
+ * Lock the page for tagging and return 'true' if the page can be tagged,
+ * 'false' if already tagged. PG_mte_tagged is never cleared and therefore the
+ * locking only happens once for page initialisation.
+ *
+ * The page MTE lock state:
+ *
+ *   Locked:	PG_mte_lock && !PG_mte_tagged
+ *   Unlocked:	!PG_mte_lock || PG_mte_tagged
+ *
+ * Acquire semantics only if the page is tagged (returning 'false').
+ */
+static inline bool try_page_mte_tagging(struct page *page)
+{
+	VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));
+
+	if (!test_and_set_bit(PG_mte_lock, &page->flags.f))
+		return true;
+
+	/*
+	 * The tags are either being initialised or may have been initialised
+	 * already. Check if the PG_mte_tagged flag has been set or wait
+	 * otherwise.
+	 */
+	smp_cond_load_acquire(&page->flags.f, VAL & (1UL << PG_mte_tagged));
+
+	return false;
+}
 
 void mte_zero_clear_page_tags(void *addr);
-void mte_sync_tags(pte_t old_pte, pte_t pte);
+void mte_sync_tags(pte_t pte, unsigned int nr_pages);
 void mte_copy_page_tags(void *kto, const void *kfrom);
 void mte_thread_init_user(void);
 void mte_thread_switch(struct task_struct *next);
@@ -56,10 +114,21 @@ size_t mte_probe_user_range(const char __user *uaddr, size_t size);
 /* unused if !CONFIG_ARM64_MTE, silence the compiler */
 #define PG_mte_tagged	0
 
+static inline void set_page_mte_tagged(struct page *page)
+{
+}
+static inline bool page_mte_tagged(struct page *page)
+{
+	return false;
+}
+static inline bool try_page_mte_tagging(struct page *page)
+{
+	return false;
+}
 static inline void mte_zero_clear_page_tags(void *addr)
 {
 }
-static inline void mte_sync_tags(pte_t old_pte, pte_t pte)
+static inline void mte_sync_tags(pte_t pte, unsigned int nr_pages)
 {
 }
 static inline void mte_copy_page_tags(void *kto, const void *kfrom)
@@ -94,6 +163,67 @@ static inline int mte_ptrace_copy_tags(struct task_struct *child,
 
 #endif /* CONFIG_ARM64_MTE */
 
+#if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_ARM64_MTE)
+static inline void folio_set_hugetlb_mte_tagged(struct folio *folio)
+{
+	VM_WARN_ON_ONCE(!folio_test_hugetlb(folio));
+
+	/*
+	 * Ensure that the tags written prior to this function are visible
+	 * before the folio flags update.
+	 */
+	smp_wmb();
+	set_bit(PG_mte_tagged, &folio->flags.f);
+
+}
+
+static inline bool folio_test_hugetlb_mte_tagged(struct folio *folio)
+{
+	bool ret = test_bit(PG_mte_tagged, &folio->flags.f);
+
+	VM_WARN_ON_ONCE(!folio_test_hugetlb(folio));
+
+	/*
+	 * If the folio is tagged, ensure ordering with a likely subsequent
+	 * read of the tags.
+	 */
+	if (ret)
+		smp_rmb();
+	return ret;
+}
+
+static inline bool folio_try_hugetlb_mte_tagging(struct folio *folio)
+{
+	VM_WARN_ON_ONCE(!folio_test_hugetlb(folio));
+
+	if (!test_and_set_bit(PG_mte_lock, &folio->flags.f))
+		return true;
+
+	/*
+	 * The tags are either being initialised or may have been initialised
+	 * already. Check if the PG_mte_tagged flag has been set or wait
+	 * otherwise.
+	 */
+	smp_cond_load_acquire(&folio->flags.f, VAL & (1UL << PG_mte_tagged));
+
+	return false;
+}
+#else
+static inline void folio_set_hugetlb_mte_tagged(struct folio *folio)
+{
+}
+
+static inline bool folio_test_hugetlb_mte_tagged(struct folio *folio)
+{
+	return false;
+}
+
+static inline bool folio_try_hugetlb_mte_tagging(struct folio *folio)
+{
+	return false;
+}
+#endif
+
 static inline void mte_disable_tco_entry(struct task_struct *task)
 {
 	if (!system_supports_mte())
@@ -115,19 +245,11 @@ static inline void mte_disable_tco_entry(struct task_struct *task)
 }
 
 #ifdef CONFIG_KASAN_HW_TAGS
-/* Whether the MTE asynchronous mode is enabled. */
-DECLARE_STATIC_KEY_FALSE(mte_async_or_asymm_mode);
-
-static inline bool system_uses_mte_async_or_asymm_mode(void)
-{
-	return static_branch_unlikely(&mte_async_or_asymm_mode);
-}
-
 void mte_check_tfsr_el1(void);
 
 static inline void mte_check_tfsr_entry(void)
 {
-	if (!system_supports_mte())
+	if (!kasan_hw_tags_enabled())
 		return;
 
 	mte_check_tfsr_el1();
@@ -135,7 +257,7 @@ static inline void mte_check_tfsr_entry(void)
 
 static inline void mte_check_tfsr_exit(void)
 {
-	if (!system_supports_mte())
+	if (!kasan_hw_tags_enabled())
 		return;
 
 	/*
@@ -149,10 +271,6 @@ static inline void mte_check_tfsr_exit(void)
 	mte_check_tfsr_el1();
 }
 #else
-static inline bool system_uses_mte_async_or_asymm_mode(void)
-{
-	return false;
-}
 static inline void mte_check_tfsr_el1(void)
 {
 }
@@ -164,5 +282,5 @@ static inline void mte_check_tfsr_exit(void)
 }
 #endif /* CONFIG_KASAN_HW_TAGS */
 
-#endif /* __ASSEMBLY__ */
+#endif /* __ASSEMBLER__ */
 #endif /* __ASM_MTE_H  */