linux-kernel - [PATCH v3 08/12] kasan/um: select ARCH_DEFER_KASAN and call kasan_init

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Message-Id: <20250717142732.292822-9-snovitoll@gmail.com>
Date: Thu, 17 Jul 2025 19:27:28 +0500
From: Sabyrzhan Tasbolatov <snovitoll@...il.com>
To: hca@...ux.ibm.com,
	christophe.leroy@...roup.eu,
	andreyknvl@...il.com,
	agordeev@...ux.ibm.com,
	akpm@...ux-foundation.org
Cc: ryabinin.a.a@...il.com,
	glider@...gle.com,
	dvyukov@...gle.com,
	kasan-dev@...glegroups.com,
	linux-kernel@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linuxppc-dev@...ts.ozlabs.org,
	linux-riscv@...ts.infradead.org,
	linux-s390@...r.kernel.org,
	linux-um@...ts.infradead.org,
	linux-mm@...ck.org,
	snovitoll@...il.com
Subject: [PATCH v3 08/12] kasan/um: select ARCH_DEFER_KASAN and call kasan_init_generic

UserMode Linux needs deferred KASAN initialization as it has a custom
kasan_arch_is_ready() implementation that tracks shadow memory readiness
via the kasan_um_is_ready flag.

Select ARCH_DEFER_KASAN to enable the unified static key mechanism
for runtime KASAN control. Call kasan_init_generic() which handles
Generic KASAN initialization and enables the static key.

Delete the key kasan_um_is_ready in favor of the unified kasan_enabled()
interface.

Note that kasan_init_generic has __init macro, which is called by
kasan_init() which is not marked with __init in arch/um code.

Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
---
Changes in v3:
- Added CONFIG_ARCH_DEFER_KASAN selection for proper runtime control
---
 arch/um/Kconfig             | 1 +
 arch/um/include/asm/kasan.h | 5 -----
 arch/um/kernel/mem.c        | 4 ++--
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index f08e8a7fac9..fd6d78bba52 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -8,6 +8,7 @@ config UML
 	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_FORTIFY_SOURCE
+	select ARCH_DEFER_KASAN
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_STRNCPY_FROM_USER
diff --git a/arch/um/include/asm/kasan.h b/arch/um/include/asm/kasan.h
index f97bb1f7b85..81bcdc0f962 100644
--- a/arch/um/include/asm/kasan.h
+++ b/arch/um/include/asm/kasan.h
@@ -24,11 +24,6 @@
 
 #ifdef CONFIG_KASAN
 void kasan_init(void);
-extern int kasan_um_is_ready;
-
-#ifdef CONFIG_STATIC_LINK
-#define kasan_arch_is_ready() (kasan_um_is_ready)
-#endif
 #else
 static inline void kasan_init(void) { }
 #endif /* CONFIG_KASAN */
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 76bec7de81b..058cb70e330 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -21,9 +21,9 @@
 #include <os.h>
 #include <um_malloc.h>
 #include <linux/sched/task.h>
+#include <linux/kasan.h>
 
 #ifdef CONFIG_KASAN
-int kasan_um_is_ready;
 void kasan_init(void)
 {
 	/*
@@ -32,7 +32,7 @@ void kasan_init(void)
 	 */
 	kasan_map_memory((void *)KASAN_SHADOW_START, KASAN_SHADOW_SIZE);
 	init_task.kasan_depth = 0;
-	kasan_um_is_ready = true;
+	kasan_init_generic();
 }
 
 static void (*kasan_init_ptr)(void)
-- 
2.34.1