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Subject[PATCH v2 13/37] kasan, arm64: only use kasan_depth for software modes
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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@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
Change-Id: I6109ea96c8df41ef6d75ad71bf22c1c8fa234a9a
---
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 afe01e232935..db38b7ecf46d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1192,7 +1192,7 @@ 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

diff --git a/init/init_task.c b/init/init_task.c
index f6889fce64af..b93078f1708b 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -173,7 +173,7 @@ 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);
--
2.28.0.618.gf4bc123cb7-goog
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