[patch 7/7] kasan: add kasan mode messages when kasan init

[Andrew Morton <akpm@linux-foundation.org>]

From: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Subject: kasan: add kasan mode messages when kasan init

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

Link: https://bugzilla.kernel.org/show_bug.cgi?id=212195 [1]
Link: https://lkml.kernel.org/r/20211020094850.4113-1-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Yee Lee <yee.lee@mediatek.com>
Cc: Nicholas Tang <nicholas.tang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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(-)

--- a/arch/arm64/mm/kasan_init.c~kasan-add-kasan-mode-messages-when-kasan-init
+++ a/arch/arm64/mm/kasan_init.c
@@ -310,7 +310,7 @@ 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
 }
 
--- a/mm/kasan/hw_tags.c~kasan-add-kasan-mode-messages-when-kasan-init
+++ a/mm/kasan/hw_tags.c
@@ -106,6 +106,16 @@ static int __init early_kasan_flag_stack
 }
 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)
--- a/mm/kasan/sw_tags.c~kasan-add-kasan-mode-messages-when-kasan-init
+++ a/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");
 }
 
 /*
_