This allows generic and sw_tags to be set in kernel cmdline too.

When at it, rename 'kasan_arg' to 'kasan_arg_disabled' as a bool
variable. And expose 'kasan_flag_enabled' to kasan common place
too.

This is prepared for later adding kernel parameter kasan=on|off for
all kasan modes.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/kasan-enabled.h |  4 +++-
 mm/kasan/common.c             | 27 +++++++++++++++++++++++++++
 mm/kasan/hw_tags.c            | 35 ++---------------------------------
 3 files changed, 32 insertions(+), 34 deletions(-)

diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
index 6f612d69ea0c..32f2d19f599f 100644
--- a/include/linux/kasan-enabled.h
+++ b/include/linux/kasan-enabled.h
@@ -4,10 +4,12 @@
 
 #include <linux/static_key.h>
 
-#ifdef CONFIG_KASAN_HW_TAGS
+extern bool kasan_arg_disabled;
 
 DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
 
+#ifdef CONFIG_KASAN_HW_TAGS
+
 static __always_inline bool kasan_enabled(void)
 {
 	return static_branch_likely(&kasan_flag_enabled);
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index ed4873e18c75..fe6937654203 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -32,6 +32,33 @@
 #include "kasan.h"
 #include "../slab.h"
 
+/*
+ * Whether KASAN is enabled at all.
+ * The value remains false until KASAN is initialized.
+ */
+DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
+EXPORT_SYMBOL(kasan_flag_enabled);
+
+bool kasan_arg_disabled;
+/* kasan=off/on */
+static int __init early_kasan_flag(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	if (!strcmp(arg, "off"))
+		kasan_arg_disabled = true;
+	else if (!strcmp(arg, "on"))
+		kasan_arg_disabled = false;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+early_param("kasan", early_kasan_flag);
+
+
+
 struct slab *kasan_addr_to_slab(const void *addr)
 {
 	if (virt_addr_valid(addr))
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 9a6927394b54..377e9c285a74 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -22,12 +22,6 @@
 
 #include "kasan.h"
 
-enum kasan_arg {
-	KASAN_ARG_DEFAULT,
-	KASAN_ARG_OFF,
-	KASAN_ARG_ON,
-};
-
 enum kasan_arg_mode {
 	KASAN_ARG_MODE_DEFAULT,
 	KASAN_ARG_MODE_SYNC,
@@ -41,17 +35,9 @@ enum kasan_arg_vmalloc {
 	KASAN_ARG_VMALLOC_ON,
 };
 
-static enum kasan_arg kasan_arg __ro_after_init;
 static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
 static enum kasan_arg_vmalloc kasan_arg_vmalloc __initdata;
 
-/*
- * Whether KASAN is enabled at all.
- * The value remains false until KASAN is initialized by kasan_init_hw_tags().
- */
-DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
-EXPORT_SYMBOL(kasan_flag_enabled);
-
 /*
  * Whether the selected mode is synchronous, asynchronous, or asymmetric.
  * Defaults to KASAN_MODE_SYNC.
@@ -85,23 +71,6 @@ unsigned int kasan_page_alloc_sample_order = PAGE_ALLOC_SAMPLE_ORDER_DEFAULT;
 
 DEFINE_PER_CPU(long, kasan_page_alloc_skip);
 
-/* kasan=off/on */
-static int __init early_kasan_flag(char *arg)
-{
-	if (!arg)
-		return -EINVAL;
-
-	if (!strcmp(arg, "off"))
-		kasan_arg = KASAN_ARG_OFF;
-	else if (!strcmp(arg, "on"))
-		kasan_arg = KASAN_ARG_ON;
-	else
-		return -EINVAL;
-
-	return 0;
-}
-early_param("kasan", early_kasan_flag);
-
 /* kasan.mode=sync/async/asymm */
 static int __init early_kasan_mode(char *arg)
 {
@@ -209,7 +178,7 @@ void kasan_init_hw_tags_cpu(void)
 	 * When this function is called, kasan_flag_enabled is not yet
 	 * set by kasan_init_hw_tags(). Thus, check kasan_arg instead.
 	 */
-	if (kasan_arg == KASAN_ARG_OFF)
+	if (kasan_arg_disabled)
 		return;
 
 	/*
@@ -227,7 +196,7 @@ void __init kasan_init_hw_tags(void)
 		return;
 
 	/* If KASAN is disabled via command line, don't initialize it. */
-	if (kasan_arg == KASAN_ARG_OFF)
+	if (kasan_arg_disabled)
 		return;
 
 	switch (kasan_arg_mode) {
-- 
2.41.0

On Tue, 5 Aug 2025 at 08:24, 'Baoquan He' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> This allows generic and sw_tags to be set in kernel cmdline too.
>
> When at it, rename 'kasan_arg' to 'kasan_arg_disabled' as a bool
> variable. And expose 'kasan_flag_enabled' to kasan common place
> too.
>
> This is prepared for later adding kernel parameter kasan=on|off for
> all kasan modes.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/kasan-enabled.h |  4 +++-
>  mm/kasan/common.c             | 27 +++++++++++++++++++++++++++
>  mm/kasan/hw_tags.c            | 35 ++---------------------------------
>  3 files changed, 32 insertions(+), 34 deletions(-)
>
> diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
> index 6f612d69ea0c..32f2d19f599f 100644
> --- a/include/linux/kasan-enabled.h
> +++ b/include/linux/kasan-enabled.h
> @@ -4,10 +4,12 @@
>
>  #include <linux/static_key.h>
>
> -#ifdef CONFIG_KASAN_HW_TAGS
> +extern bool kasan_arg_disabled;
>
>  DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
>
> +#ifdef CONFIG_KASAN_HW_TAGS
> +
>  static __always_inline bool kasan_enabled(void)
>  {
>         return static_branch_likely(&kasan_flag_enabled);
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index ed4873e18c75..fe6937654203 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -32,6 +32,33 @@
>  #include "kasan.h"
>  #include "../slab.h"
>
> +/*
> + * Whether KASAN is enabled at all.
> + * The value remains false until KASAN is initialized.
> + */
> +DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
> +EXPORT_SYMBOL(kasan_flag_enabled);
> +
> +bool kasan_arg_disabled;

You lost __ro_after_init

> +/* kasan=off/on */
> +static int __init early_kasan_flag(char *arg)
> +{
> +       if (!arg)
> +               return -EINVAL;
> +
> +       if (!strcmp(arg, "off"))
> +               kasan_arg_disabled = true;
> +       else if (!strcmp(arg, "on"))
> +               kasan_arg_disabled = false;
> +       else
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +early_param("kasan", early_kasan_flag);
> +
> +
> +

Why extra blank lines?

On 08/06/25 at 09:11am, Marco Elver wrote:
> On Tue, 5 Aug 2025 at 08:24, 'Baoquan He' via kasan-dev
> <kasan-dev@googlegroups.com> wrote:
> >
> > This allows generic and sw_tags to be set in kernel cmdline too.
> >
> > When at it, rename 'kasan_arg' to 'kasan_arg_disabled' as a bool
> > variable. And expose 'kasan_flag_enabled' to kasan common place
> > too.
> >
> > This is prepared for later adding kernel parameter kasan=on|off for
> > all kasan modes.
> >
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  include/linux/kasan-enabled.h |  4 +++-
> >  mm/kasan/common.c             | 27 +++++++++++++++++++++++++++
> >  mm/kasan/hw_tags.c            | 35 ++---------------------------------
> >  3 files changed, 32 insertions(+), 34 deletions(-)
> >
> > diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
> > index 6f612d69ea0c..32f2d19f599f 100644
> > --- a/include/linux/kasan-enabled.h
> > +++ b/include/linux/kasan-enabled.h
> > @@ -4,10 +4,12 @@
> >
> >  #include <linux/static_key.h>
> >
> > -#ifdef CONFIG_KASAN_HW_TAGS
> > +extern bool kasan_arg_disabled;
> >
> >  DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
> >
> > +#ifdef CONFIG_KASAN_HW_TAGS
> > +
> >  static __always_inline bool kasan_enabled(void)
> >  {
> >         return static_branch_likely(&kasan_flag_enabled);
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index ed4873e18c75..fe6937654203 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -32,6 +32,33 @@
> >  #include "kasan.h"
> >  #include "../slab.h"
> >
> > +/*
> > + * Whether KASAN is enabled at all.
> > + * The value remains false until KASAN is initialized.
> > + */
> > +DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
> > +EXPORT_SYMBOL(kasan_flag_enabled);
> > +
> > +bool kasan_arg_disabled;
> 
> You lost __ro_after_init

Right, thanks for careful reviewing.

> 
> > +/* kasan=off/on */
> > +static int __init early_kasan_flag(char *arg)
> > +{
> > +       if (!arg)
> > +               return -EINVAL;
> > +
> > +       if (!strcmp(arg, "off"))
> > +               kasan_arg_disabled = true;
> > +       else if (!strcmp(arg, "on"))
> > +               kasan_arg_disabled = false;
> > +       else
> > +               return -EINVAL;
> > +
> > +       return 0;
> > +}
> > +early_param("kasan", early_kasan_flag);
> > +
> > +
> > +
> 
> Why extra blank lines?

Good catch, will remove it in v2. Thanks.