[PATCH mm] kasan: export HW_TAGS symbols for KUnit tests

Currently, building KASAN-KUnit tests as a module fails with:

ERROR: modpost: "mte_enable_kernel" [lib/test_kasan.ko] undefined!
ERROR: modpost: "mte_set_report_once" [lib/test_kasan.ko] undefined!

This change adds KASAN wrappers for mte_enable_kernel() and
mte_set_report_once() and only defines and exports them when KASAN-KUnit
tests are enabled.

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Signed-off-by: Andrey Konovalov <redacted>

---

Changes v1->v2:
- Add wrappers instead of exporting MTE symbols directly.
- Only define and export wrappers when KASAN-KUnit tests are enabled.

---
 lib/test_kasan.c   |  6 +++---
 mm/kasan/hw_tags.c | 16 ++++++++++++++++
 mm/kasan/kasan.h   | 12 ++++++++++++
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 1328c468fdb5..e5647d147b35 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c

@@ -53,13 +53,13 @@ static int kasan_test_init(struct kunit *test)
 	}
 
 	multishot = kasan_save_enable_multi_shot();
-	hw_set_tagging_report_once(false);
+	kasan_set_tagging_report_once(false);
 	return 0;
 }
 
 static void kasan_test_exit(struct kunit *test)
 {
-	hw_set_tagging_report_once(true);
+	kasan_set_tagging_report_once(true);
 	kasan_restore_multi_shot(multishot);
 }
 

@@ -97,7 +97,7 @@ static void kasan_test_exit(struct kunit *test)
 			READ_ONCE(fail_data.report_found));	\
 	if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) {			\
 		if (READ_ONCE(fail_data.report_found))		\
-			hw_enable_tagging();			\
+			kasan_enable_tagging();			\
 		migrate_enable();				\
 	}							\
 } while (0)

diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 1dfe4f62a89e..2aad21fda156 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c

@@ -185,3 +185,19 @@ struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 
 	return &alloc_meta->free_track[0];
 }
+
+#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+
+void kasan_set_tagging_report_once(bool state)
+{
+	hw_set_tagging_report_once(state);
+}
+EXPORT_SYMBOL_GPL(kasan_set_tagging_report_once);
+
+void kasan_enable_tagging(void)
+{
+	hw_enable_tagging();
+}
+EXPORT_SYMBOL_GPL(kasan_enable_tagging);
+
+#endif

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cc787ba47e1b..3436c6bf7c0c 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h

@@ -308,6 +308,18 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #endif /* CONFIG_KASAN_HW_TAGS */
 
+#if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+
+void kasan_set_tagging_report_once(bool state);
+void kasan_enable_tagging(void);
+
+#else /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
+
+static inline void kasan_set_tagging_report_once(bool state) { }
+static inline void kasan_enable_tagging(void) { }
+
+#endif /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
+
 #ifdef CONFIG_KASAN_SW_TAGS
 u8 kasan_random_tag(void);
 #elif defined(CONFIG_KASAN_HW_TAGS)

-- 
2.30.0.478.g8a0d178c01-goog


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On Fri, 12 Feb 2021 21:08:52 +0100 Andrey Konovalov [off-list ref] wrote:

Currently, building KASAN-KUnit tests as a module fails with:

ERROR: modpost: "mte_enable_kernel" [lib/test_kasan.ko] undefined!
ERROR: modpost: "mte_set_report_once" [lib/test_kasan.ko] undefined!

This change adds KASAN wrappers for mte_enable_kernel() and
mte_set_report_once() and only defines and exports them when KASAN-KUnit
tests are enabled.

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Please confirm that this is applicable to current Linus mainline?

Today is pretty much the last day for getting material into 5.11, and
this patch has been churning somewhat.

So I think it would be better to merge this into 5.12-rc1, with a
cc:stable so it goes into 5.11.1.

For which we'll need a Fixes:, please?

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On Fri, Feb 12, 2021 at 9:16 PM Andrew Morton [off-list ref] wrote:

On Fri, 12 Feb 2021 21:08:52 +0100 Andrey Konovalov [off-list ref] wrote:

quoted

Currently, building KASAN-KUnit tests as a module fails with:

ERROR: modpost: "mte_enable_kernel" [lib/test_kasan.ko] undefined!
ERROR: modpost: "mte_set_report_once" [lib/test_kasan.ko] undefined!

This change adds KASAN wrappers for mte_enable_kernel() and
mte_set_report_once() and only defines and exports them when KASAN-KUnit
tests are enabled.

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Please confirm that this is applicable to current Linus mainline?

It's not applicable. KUnit tests for HW_TAGS aren't supported there,
the patches for that are in mm only. So no need to put it into 5.11.

Today is pretty much the last day for getting material into 5.11, and
this patch has been churning somewhat.

So I think it would be better to merge this into 5.12-rc1, with a
cc:stable so it goes into 5.11.1.

For which we'll need a Fixes:, please?

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On Fri, 12 Feb 2021 21:21:39 +0100 Andrey Konovalov [off-list ref] wrote:

quoted

quoted

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Please confirm that this is applicable to current Linus mainline?

It's not applicable. KUnit tests for HW_TAGS aren't supported there,
the patches for that are in mm only. So no need to put it into 5.11.

So... which -mm patch does this patch fix?

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On Fri, Feb 12, 2021 at 9:54 PM Andrew Morton [off-list ref] wrote:

On Fri, 12 Feb 2021 21:21:39 +0100 Andrey Konovalov [off-list ref] wrote:

quoted

quoted

quoted

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Please confirm that this is applicable to current Linus mainline?

It's not applicable. KUnit tests for HW_TAGS aren't supported there,
the patches for that are in mm only. So no need to put it into 5.11.

So... which -mm patch does this patch fix?

"kasan, arm64: allow using KUnit tests with HW_TAGS mode".

There will be some minor adjacent-line-changed conflicts if you decide
to squash it.

Alternatively, this can go as a separate patch after the tests series
(after "kasan: don't run tests when KASAN is not enabled").

Thanks!

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On Fri, 12 Feb 2021 22:01:38 +0100 Andrey Konovalov [off-list ref] wrote:

On Fri, Feb 12, 2021 at 9:54 PM Andrew Morton [off-list ref] wrote:

quoted

On Fri, 12 Feb 2021 21:21:39 +0100 Andrey Konovalov [off-list ref] wrote:

quoted

quoted

quoted

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Please confirm that this is applicable to current Linus mainline?

It's not applicable. KUnit tests for HW_TAGS aren't supported there,
the patches for that are in mm only. So no need to put it into 5.11.

So... which -mm patch does this patch fix?

"kasan, arm64: allow using KUnit tests with HW_TAGS mode".

There will be some minor adjacent-line-changed conflicts if you decide
to squash it.

Alternatively, this can go as a separate patch after the tests series
(after "kasan: don't run tests when KASAN is not enabled").

Thanks - it wasn't obvious.

I staged it as a fix against "kasan, arm64: allow using KUnit tests
with HW_TAGS mode".  To make the series as nice as we can, and to avoid
bisection holes.


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On Fri, Feb 12, 2021 at 10:08 PM Andrew Morton
[off-list ref] wrote:

On Fri, 12 Feb 2021 22:01:38 +0100 Andrey Konovalov [off-list ref] wrote:

quoted

On Fri, Feb 12, 2021 at 9:54 PM Andrew Morton [off-list ref] wrote:

quoted

On Fri, 12 Feb 2021 21:21:39 +0100 Andrey Konovalov [off-list ref] wrote:

quoted

quoted

quoted

The wrappers aren't defined when tests aren't enabled to avoid misuse.
The mte_() functions aren't exported directly to avoid having low-level
KASAN ifdefs in the arch code.

Please confirm that this is applicable to current Linus mainline?

It's not applicable. KUnit tests for HW_TAGS aren't supported there,
the patches for that are in mm only. So no need to put it into 5.11.

So... which -mm patch does this patch fix?

"kasan, arm64: allow using KUnit tests with HW_TAGS mode".

There will be some minor adjacent-line-changed conflicts if you decide
to squash it.

Alternatively, this can go as a separate patch after the tests series
(after "kasan: don't run tests when KASAN is not enabled").

Thanks - it wasn't obvious.

I staged it as a fix against "kasan, arm64: allow using KUnit tests
with HW_TAGS mode".  To make the series as nice as we can, and to avoid
bisection holes.

Sounds good, thank you!

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