[PATCH v3] kasan: add kasan mode messages when kasan init

[Kuan-Ying Lee]

There are multiple kasan modes. It makes sense that we add some messages
to know which kasan mode is when booting up. see [1].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=212195 [1]
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx>
---
v3:
 - Rebase to linux-next
 - Move kasan_mode_info() into hw_tags.c
v2:
 - Rebase to linux-next
 - HW-tag based mode need to consider asymm mode
 - Thanks Marco's suggestion

 arch/arm64/mm/kasan_init.c |  2 +-
 mm/kasan/hw_tags.c         | 14 +++++++++++++-
 mm/kasan/sw_tags.c         |  2 +-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 5b996ca4d996..6f5a6fe8edd7 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -309,7 +309,7 @@ void __init kasan_init(void)
 	kasan_init_depth();
 #if defined(CONFIG_KASAN_GENERIC)
 	/* CONFIG_KASAN_SW_TAGS also requires kasan_init_sw_tags(). */
-	pr_info("KernelAddressSanitizer initialized\n");
+	pr_info("KernelAddressSanitizer initialized (generic)\n");
 #endif
 }
 
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index dc892119e88f..7355cb534e4f 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -106,6 +106,16 @@ static int __init early_kasan_flag_stacktrace(char *arg)
 }
 early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
 
+static inline const char *kasan_mode_info(void)
+{
+	if (kasan_mode == KASAN_MODE_ASYNC)
+		return "async";
+	else if (kasan_mode == KASAN_MODE_ASYMM)
+		return "asymm";
+	else
+		return "sync";
+}
+
 /* kasan_init_hw_tags_cpu() is called for each CPU. */
 void kasan_init_hw_tags_cpu(void)
 {
@@ -177,7 +187,9 @@ void __init kasan_init_hw_tags(void)
 		break;
 	}
 
-	pr_info("KernelAddressSanitizer initialized\n");
+	pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, stacktrace=%s)\n",
+		kasan_mode_info(),
+		kasan_stack_collection_enabled() ? "on" : "off");
 }
 
 void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
index bd3f540feb47..77f13f391b57 100644
--- a/mm/kasan/sw_tags.c
+++ b/mm/kasan/sw_tags.c
@@ -42,7 +42,7 @@ void __init kasan_init_sw_tags(void)
 	for_each_possible_cpu(cpu)
 		per_cpu(prng_state, cpu) = (u32)get_cycles();
 
-	pr_info("KernelAddressSanitizer initialized\n");
+	pr_info("KernelAddressSanitizer initialized (sw-tags)\n");
 }
 
 /*
-- 
2.18.0