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 three kasan modes.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
include/linux/kasan-enabled.h | 4 +++-
mm/kasan/common.c | 20 ++++++++++++++++++--
mm/kasan/hw_tags.c | 28 ++--------------------------
3 files changed, 23 insertions(+), 29 deletions(-)
diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
index 9eca967d8526..b05ec6329fbe 100644
--- a/include/linux/kasan-enabled.h
+++ b/include/linux/kasan-enabled.h
@@ -4,13 +4,15 @@
#include <linux/static_key.h>
-#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
+extern bool kasan_arg_disabled;
+
/*
* Global runtime flag for KASAN modes that need runtime control.
* Used by ARCH_DEFER_KASAN architectures and HW_TAGS mode.
*/
DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
+#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
/*
* Runtime control for shadow memory initialization or HW_TAGS mode.
* Uses static key for architectures that need deferred KASAN or HW_TAGS.
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 1d27f1bd260b..ac14956986ee 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -32,14 +32,30 @@
#include "kasan.h"
#include "../slab.h"
-#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
/*
* Definition of the unified static key declared in kasan-enabled.h.
* This provides consistent runtime enable/disable across KASAN modes.
*/
DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
EXPORT_SYMBOL_GPL(kasan_flag_enabled);
-#endif
+
+bool kasan_arg_disabled __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);
struct slab *kasan_addr_to_slab(const void *addr)
{
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 1c373cc4b3fa..709c91abc1b1 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,
@@ -41,7 +35,6 @@ 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;
@@ -81,23 +74,6 @@ 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)
{
@@ -222,7 +198,7 @@ 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;
/*
@@ -240,7 +216,7 @@ 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 Fri, Nov 28, 2025 at 4:33 AM Baoquan He <bhe@redhat.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 asks to be two separate patches.
>
> This is prepared for later adding kernel parameter kasan=on|off for
> all three kasan modes.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> include/linux/kasan-enabled.h | 4 +++-
> mm/kasan/common.c | 20 ++++++++++++++++++--
> mm/kasan/hw_tags.c | 28 ++--------------------------
> 3 files changed, 23 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
> index 9eca967d8526..b05ec6329fbe 100644
> --- a/include/linux/kasan-enabled.h
> +++ b/include/linux/kasan-enabled.h
> @@ -4,13 +4,15 @@
>
> #include <linux/static_key.h>
>
> -#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
These changes of moving/removing CONFIG_ARCH_DEFER_KASAN also seem to
belong to a separate patch (or should be combined with patch 12?); the
commit message does not even mention them.
> +extern bool kasan_arg_disabled;
> +
> /*
> * Global runtime flag for KASAN modes that need runtime control.
> * Used by ARCH_DEFER_KASAN architectures and HW_TAGS mode.
> */
> DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
So kasan_flag_enabled is now always exposed here...
>
> +#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
but the functions that use it are not. Why?
> /*
> * Runtime control for shadow memory initialization or HW_TAGS mode.
> * Uses static key for architectures that need deferred KASAN or HW_TAGS.
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 1d27f1bd260b..ac14956986ee 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -32,14 +32,30 @@
> #include "kasan.h"
> #include "../slab.h"
>
> -#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
> /*
> * Definition of the unified static key declared in kasan-enabled.h.
> * This provides consistent runtime enable/disable across KASAN modes.
> */
> DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
> EXPORT_SYMBOL_GPL(kasan_flag_enabled);
> -#endif
> +
> +bool kasan_arg_disabled __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);
>
> struct slab *kasan_addr_to_slab(const void *addr)
> {
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index 1c373cc4b3fa..709c91abc1b1 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,
> @@ -41,7 +35,6 @@ 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;
>
> @@ -81,23 +74,6 @@ 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)
> {
> @@ -222,7 +198,7 @@ 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;
>
> /*
> @@ -240,7 +216,7 @@ 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 12/04/25 at 05:39pm, Andrey Konovalov wrote:
> On Fri, Nov 28, 2025 at 4:33 AM Baoquan He <bhe@redhat.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 asks to be two separate patches.
Makes sense to me, thanks..
>
> >
> > This is prepared for later adding kernel parameter kasan=on|off for
> > all three kasan modes.
> >
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> > include/linux/kasan-enabled.h | 4 +++-
> > mm/kasan/common.c | 20 ++++++++++++++++++--
> > mm/kasan/hw_tags.c | 28 ++--------------------------
> > 3 files changed, 23 insertions(+), 29 deletions(-)
> >
> > diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
> > index 9eca967d8526..b05ec6329fbe 100644
> > --- a/include/linux/kasan-enabled.h
> > +++ b/include/linux/kasan-enabled.h
> > @@ -4,13 +4,15 @@
> >
> > #include <linux/static_key.h>
> >
> > -#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
>
> These changes of moving/removing CONFIG_ARCH_DEFER_KASAN also seem to
> belong to a separate patch (or should be combined with patch 12?); the
> commit message does not even mention them.
Yes, combining tit with patch 12 sounds great. I will move patch 12 to
earlier oder.
>
> > +extern bool kasan_arg_disabled;
> > +
> > /*
> > * Global runtime flag for KASAN modes that need runtime control.
> > * Used by ARCH_DEFER_KASAN architectures and HW_TAGS mode.
> > */
> > DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
>
> So kasan_flag_enabled is now always exposed here...
>
> >
> > +#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
>
> but the functions that use it are not. Why?
Good question. I didn't consider this reasonably. At the beginning, I
thought it could cause problem if people has specified 'kasan=off'
before patch 12 when bisecting. That's why put kasan_arg_disabled and
kasan_flag_enabled declaration outside of any ifdeffery scope. Now after
reconsiderring, putting patch 12 earlier can solve the problem.
Thanks for careful reivewing, all suggestions are good and taken.
>
>
> > /*
> > * Runtime control for shadow memory initialization or HW_TAGS mode.
> > * Uses static key for architectures that need deferred KASAN or HW_TAGS.
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 1d27f1bd260b..ac14956986ee 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -32,14 +32,30 @@
> > #include "kasan.h"
> > #include "../slab.h"
> >
> > -#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS)
> > /*
> > * Definition of the unified static key declared in kasan-enabled.h.
> > * This provides consistent runtime enable/disable across KASAN modes.
> > */
> > DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
> > EXPORT_SYMBOL_GPL(kasan_flag_enabled);
> > -#endif
> > +
> > +bool kasan_arg_disabled __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);
> >
> > struct slab *kasan_addr_to_slab(const void *addr)
> > {
> > diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> > index 1c373cc4b3fa..709c91abc1b1 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,
> > @@ -41,7 +35,6 @@ 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;
> >
> > @@ -81,23 +74,6 @@ 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)
> > {
> > @@ -222,7 +198,7 @@ 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;
> >
> > /*
> > @@ -240,7 +216,7 @@ 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
> >
>
© 2016 - 2026 Red Hat, Inc.