kasan, arm64: move initialization message

Software tag-based KASAN mode is fully initialized with kasan_init_tags(),
while the generic mode only requires kasan_init().  Move the
initialization message for tag-based mode into kasan_init_tags().

Also fix pr_fmt() usage for KASAN code: generic.c doesn't need it as it
doesn't use any printing functions; tag-based mode should use "kasan:"
instead of KBUILD_MODNAME (which stands for file name).

Link: https://lkml.kernel.org/r/29a30ea4e1750450dd1f693d25b7b6cb05913ecf.1606161801.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm64/include/asm/kasan.h

@@ -12,14 +12,10 @@
 #define arch_kasan_reset_tag(addr)	__tag_reset(addr)
 #define arch_kasan_get_tag(addr)	__tag_get(addr)
 
-#ifdef CONFIG_KASAN
-void kasan_init(void);
-#else
-static inline void kasan_init(void) { }
-#endif
-
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 
+void kasan_init(void);
+
 /*
  * KASAN_SHADOW_START: beginning of the kernel virtual addresses.
  * KASAN_SHADOW_END: KASAN_SHADOW_START + 1/N of kernel virtual addresses,
@@ -43,6 +39,7 @@ void kasan_copy_shadow(pgd_t *pgdir);
 asmlinkage void kasan_early_init(void);
 
 #else
+static inline void kasan_init(void) { }
 static inline void kasan_copy_shadow(pgd_t *pgdir) { }
 #endif
 

arch/arm64/mm/kasan_init.c

@@ -278,17 +278,14 @@ static void __init kasan_init_depth(void)
 	init_task.kasan_depth = 0;
 }
 
-#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) */
-
-static inline void __init kasan_init_shadow(void) { }
-
-static inline void __init kasan_init_depth(void) { }
-
-#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
-
 void __init kasan_init(void)
 {
 	kasan_init_shadow();
 	kasan_init_depth();
+#if defined(CONFIG_KASAN_GENERIC)
+	/* CONFIG_KASAN_SW_TAGS also requires kasan_init_tags(). */
 	pr_info("KernelAddressSanitizer initialized\n");
+#endif
 }
+
+#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */

mm/kasan/generic.c

@@ -9,8 +9,6 @@
  *        Andrey Konovalov <andreyknvl@gmail.com>
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/export.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>

mm/kasan/sw_tags.c

@@ -6,7 +6,7 @@
  * Author: Andrey Konovalov <andreyknvl@google.com>
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define pr_fmt(fmt) "kasan: " fmt
 
 #include <linux/export.h>
 #include <linux/interrupt.h>
@@ -41,6 +41,8 @@ void kasan_init_tags(void)
 
 	for_each_possible_cpu(cpu)
 		per_cpu(prng_state, cpu) = (u32)get_cycles();
+
+	pr_info("KernelAddressSanitizer initialized\n");
 }
 
 /*