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Date:   Fri, 14 Aug 2020 19:26:55 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        kasan-dev@...glegroups.com
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Elena Petrova <lenaptr@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 13/35] kasan, arm64: only use kasan_depth for software modes

This is a preparatory commit for the upcoming addition of a new hardware
tag-based (MTE-based) KASAN mode.

Hardware tag-based KASAN won't use kasan_depth. Only define and use it
when one of the software KASAN modes are enabled.

No functional changes for software modes.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 arch/arm64/mm/kasan_init.c | 11 ++++++++---
 include/linux/kasan.h      | 14 ++++++++++----
 include/linux/sched.h      |  2 +-
 init/init_task.c           |  2 +-
 mm/kasan/common.c          |  2 ++
 mm/kasan/report.c          |  2 ++
 6 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 4d35eaf3ec97..b6b9d55bb72e 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -273,17 +273,22 @@ static void __init kasan_init_shadow(void)
 	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 }
 
+void __init kasan_init_depth(void)
+{
+	init_task.kasan_depth = 0;
+}
+
 #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) */
 
 static inline void __init kasan_init_shadow(void) { }
 
+static inline void __init kasan_init_depth(void) { }
+
 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 
 void __init kasan_init(void)
 {
 	kasan_init_shadow();
-
-	/* At this point kasan is fully initialized. Enable error messages */
-	init_task.kasan_depth = 0;
+	kasan_init_depth();
 	pr_info("KernelAddressSanitizer initialized\n");
 }
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 18617d5c4cd7..894f4d9163ee 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -52,7 +52,7 @@ static inline void kasan_remove_zero_shadow(void *start,
 
 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 
-#ifdef CONFIG_KASAN
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 
 /* Enable reporting bugs after kasan_disable_current() */
 extern void kasan_enable_current(void);
@@ -60,6 +60,15 @@ extern void kasan_enable_current(void);
 /* Disable reporting bugs for current task */
 extern void kasan_disable_current(void);
 
+#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
+
+static inline void kasan_enable_current(void) {}
+static inline void kasan_disable_current(void) {}
+
+#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
+
+#ifdef CONFIG_KASAN
+
 void kasan_unpoison_memory(const void *address, size_t size);
 
 void kasan_unpoison_task_stack(struct task_struct *task);
@@ -110,9 +119,6 @@ static inline void kasan_unpoison_memory(const void *address, size_t size) {}
 
 static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
 
-static inline void kasan_enable_current(void) {}
-static inline void kasan_disable_current(void) {}
-
 static inline void kasan_alloc_pages(struct page *page, unsigned int order) {}
 static inline void kasan_free_pages(struct page *page, unsigned int order) {}
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 692e327d7455..6dca19f2516c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1194,7 +1194,7 @@ struct task_struct {
 	u64				timer_slack_ns;
 	u64				default_timer_slack_ns;
 
-#ifdef CONFIG_KASAN
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 	unsigned int			kasan_depth;
 #endif
 #ifdef CONFIG_KCSAN
diff --git a/init/init_task.c b/init/init_task.c
index 15089d15010a..13f1cf21412b 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -171,7 +171,7 @@ struct task_struct init_task
 	.numa_group	= NULL,
 	.numa_faults	= NULL,
 #endif
-#ifdef CONFIG_KASAN
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 	.kasan_depth	= 1,
 #endif
 #ifdef CONFIG_KCSAN
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index a2321d35390e..41c7f1105eaa 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -51,6 +51,7 @@ void kasan_set_track(struct kasan_track *track, gfp_t flags)
 	track->stack = kasan_save_stack(flags);
 }
 
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 void kasan_enable_current(void)
 {
 	current->kasan_depth++;
@@ -60,6 +61,7 @@ void kasan_disable_current(void)
 {
 	current->kasan_depth--;
 }
+#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 
 static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
 {
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index ddaf9d14ca81..8463e35b489f 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -295,8 +295,10 @@ static void print_shadow_for_address(const void *addr)
 
 static bool report_enabled(void)
 {
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 	if (current->kasan_depth)
 		return false;
+#endif
 	if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
 		return true;
 	return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
-- 
2.28.0.220.ged08abb693-goog

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