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

[Andrey Konovalov]

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 <andre...@google.com>

---

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

[Andrew Morton]

On Fri, 12 Feb 2021 21:08:52 +0100 Andrey Konovalov <andre...@google.com> 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?

[Andrey Konovalov]

On Fri, Feb 12, 2021 at 9:16 PM Andrew Morton <ak...@linux-foundation.org> wrote:
>
> On Fri, 12 Feb 2021 21:08:52 +0100 Andrey Konovalov <andre...@google.com> 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?

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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[Andrew Morton]

On Fri, 12 Feb 2021 21:21:39 +0100 Andrey Konovalov <andre...@google.com> wrote:

> > > 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?

[Andrey Konovalov]

"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!

[Andrew Morton]

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.

[Andrey Konovalov]

On Fri, Feb 12, 2021 at 10:08 PM Andrew Morton

Sounds good, thank you!