diff mbox series

[v9,10/44] kasan: define KASAN_GRANULE_PAGE

Message ID 85aba371903b749412fac34e44e54c89e5ddae30.1605046192.git.andreyknvl@google.com (mailing list archive)
State New, archived
Headers show
Series kasan: add hardware tag-based mode for arm64 | expand

Commit Message

Andrey Konovalov Nov. 10, 2020, 10:10 p.m. UTC 
Define KASAN_GRANULE_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is
the same as (KASAN_GRANULE_SIZE * PAGE_SIZE), and use it across KASAN code
to simplify it.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
---
Change-Id: I0b627b24187d06c8b9bb2f1d04d94b3d06945e73
---
 mm/kasan/init.c   | 10 ++++------
 mm/kasan/kasan.h  |  1 +
 mm/kasan/shadow.c | 16 +++++++---------
 3 files changed, 12 insertions(+), 15 deletions(-)

Comments

Alexander Potapenko Nov. 11, 2020, 2:13 p.m. UTC | #1 
On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> Define KASAN_GRANULE_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is
> the same as (KASAN_GRANULE_SIZE * PAGE_SIZE), and use it across KASAN code
> to simplify it.

What's the physical sense behind KASAN_GRANULE_PAGE? Is it something
more than just a product of two constants?
The name suggests it might be something page-sized, but in reality it is not.

>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Reviewed-by: Marco Elver <elver@google.com>
> ---
> Change-Id: I0b627b24187d06c8b9bb2f1d04d94b3d06945e73
> ---
>  mm/kasan/init.c   | 10 ++++------
>  mm/kasan/kasan.h  |  1 +
>  mm/kasan/shadow.c | 16 +++++++---------
>  3 files changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> index 1a71eaa8c5f9..26b2663b3a42 100644
> --- a/mm/kasan/init.c
> +++ b/mm/kasan/init.c
> @@ -441,9 +441,8 @@ void kasan_remove_zero_shadow(void *start, unsigned long size)
>         addr = (unsigned long)kasan_mem_to_shadow(start);
>         end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
>
> -       if (WARN_ON((unsigned long)start %
> -                       (KASAN_GRANULE_SIZE * PAGE_SIZE)) ||
> -           WARN_ON(size % (KASAN_GRANULE_SIZE * PAGE_SIZE)))
> +       if (WARN_ON((unsigned long)start % KASAN_GRANULE_PAGE) ||
> +           WARN_ON(size % KASAN_GRANULE_PAGE))
>                 return;
>
>         for (; addr < end; addr = next) {
> @@ -476,9 +475,8 @@ int kasan_add_zero_shadow(void *start, unsigned long size)
>         shadow_start = kasan_mem_to_shadow(start);
>         shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
>
> -       if (WARN_ON((unsigned long)start %
> -                       (KASAN_GRANULE_SIZE * PAGE_SIZE)) ||
> -           WARN_ON(size % (KASAN_GRANULE_SIZE * PAGE_SIZE)))
> +       if (WARN_ON((unsigned long)start % KASAN_GRANULE_PAGE) ||
> +           WARN_ON(size % KASAN_GRANULE_PAGE))
>                 return -EINVAL;
>
>         ret = kasan_populate_early_shadow(shadow_start, shadow_end);
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index c31e2c739301..1865bb92d47a 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -7,6 +7,7 @@
>
>  #define KASAN_GRANULE_SIZE     (1UL << KASAN_SHADOW_SCALE_SHIFT)
>  #define KASAN_GRANULE_MASK     (KASAN_GRANULE_SIZE - 1)
> +#define KASAN_GRANULE_PAGE     (KASAN_GRANULE_SIZE << PAGE_SHIFT)
>
>  #define KASAN_TAG_KERNEL       0xFF /* native kernel pointers tag */
>  #define KASAN_TAG_INVALID      0xFE /* inaccessible memory tag */
> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
> index ca0cc4c31454..1fadd4930d54 100644
> --- a/mm/kasan/shadow.c
> +++ b/mm/kasan/shadow.c
> @@ -161,7 +161,7 @@ static int __meminit kasan_mem_notifier(struct notifier_block *nb,
>         shadow_end = shadow_start + shadow_size;
>
>         if (WARN_ON(mem_data->nr_pages % KASAN_GRANULE_SIZE) ||
> -               WARN_ON(start_kaddr % (KASAN_GRANULE_SIZE << PAGE_SHIFT)))
> +               WARN_ON(start_kaddr % KASAN_GRANULE_PAGE))
>                 return NOTIFY_BAD;
>
>         switch (action) {
> @@ -432,22 +432,20 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
>         unsigned long region_start, region_end;
>         unsigned long size;
>
> -       region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE);
> -       region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE);
> +       region_start = ALIGN(start, KASAN_GRANULE_PAGE);
> +       region_end = ALIGN_DOWN(end, KASAN_GRANULE_PAGE);
>
> -       free_region_start = ALIGN(free_region_start,
> -                                 PAGE_SIZE * KASAN_GRANULE_SIZE);
> +       free_region_start = ALIGN(free_region_start, KASAN_GRANULE_PAGE);
>
>         if (start != region_start &&
>             free_region_start < region_start)
> -               region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE;
> +               region_start -= KASAN_GRANULE_PAGE;
>
> -       free_region_end = ALIGN_DOWN(free_region_end,
> -                                    PAGE_SIZE * KASAN_GRANULE_SIZE);
> +       free_region_end = ALIGN_DOWN(free_region_end, KASAN_GRANULE_PAGE);
>
>         if (end != region_end &&
>             free_region_end > region_end)
> -               region_end += PAGE_SIZE * KASAN_GRANULE_SIZE;
> +               region_end += KASAN_GRANULE_PAGE;
>
>         shadow_start = kasan_mem_to_shadow((void *)region_start);
>         shadow_end = kasan_mem_to_shadow((void *)region_end);
> --
> 2.29.2.222.g5d2a92d10f8-goog
>
Andrey Konovalov Nov. 11, 2020, 6:47 p.m. UTC | #2 
On Wed, Nov 11, 2020 at 3:13 PM Alexander Potapenko <glider@google.com> wrote:
>
> On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> > Define KASAN_GRANULE_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is
> > the same as (KASAN_GRANULE_SIZE * PAGE_SIZE), and use it across KASAN code
> > to simplify it.
>
> What's the physical sense behind KASAN_GRANULE_PAGE? Is it something
> more than just a product of two constants?

No, just a product.

> The name suggests it might be something page-sized, but in reality it is not.

What name would you prefer?
Marco Elver Nov. 11, 2020, 7:04 p.m. UTC | #3 
On Wed, 11 Nov 2020 at 19:48, Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Wed, Nov 11, 2020 at 3:13 PM Alexander Potapenko <glider@google.com> wrote:
> >
> > On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> > >
> > > Define KASAN_GRANULE_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is
> > > the same as (KASAN_GRANULE_SIZE * PAGE_SIZE), and use it across KASAN code
> > > to simplify it.
> >
> > What's the physical sense behind KASAN_GRANULE_PAGE? Is it something
> > more than just a product of two constants?
>
> No, just a product.
>
> > The name suggests it might be something page-sized, but in reality it is not.
>
> What name would you prefer?

Is it actually KASAN_GRANULES_PER_SHADOW_PAGE ?   AFAIK we're trying
to calculate the granules that we can fit into a page of shadow
memory.
Andrey Konovalov Nov. 12, 2020, 12:05 a.m. UTC | #4 
On Wed, Nov 11, 2020 at 8:05 PM Marco Elver <elver@google.com> wrote:
>
> On Wed, 11 Nov 2020 at 19:48, Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> > On Wed, Nov 11, 2020 at 3:13 PM Alexander Potapenko <glider@google.com> wrote:
> > >
> > > On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> > > >
> > > > Define KASAN_GRANULE_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is
> > > > the same as (KASAN_GRANULE_SIZE * PAGE_SIZE), and use it across KASAN code
> > > > to simplify it.
> > >
> > > What's the physical sense behind KASAN_GRANULE_PAGE? Is it something
> > > more than just a product of two constants?
> >
> > No, just a product.
> >
> > > The name suggests it might be something page-sized, but in reality it is not.
> >
> > What name would you prefer?
>
> Is it actually KASAN_GRANULES_PER_SHADOW_PAGE ?   AFAIK we're trying
> to calculate the granules that we can fit into a page of shadow
> memory.

Not exactly, it's the amount of memory, not the number of granules.

Will name it KASAN_MEMORY_PER_SHADOW_PAGE in v10.
diff mbox series

Patch

diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index 1a71eaa8c5f9..26b2663b3a42 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -441,9 +441,8 @@  void kasan_remove_zero_shadow(void *start, unsigned long size)
 	addr = (unsigned long)kasan_mem_to_shadow(start);
 	end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
 
-	if (WARN_ON((unsigned long)start %
-			(KASAN_GRANULE_SIZE * PAGE_SIZE)) ||
-	    WARN_ON(size % (KASAN_GRANULE_SIZE * PAGE_SIZE)))
+	if (WARN_ON((unsigned long)start % KASAN_GRANULE_PAGE) ||
+	    WARN_ON(size % KASAN_GRANULE_PAGE))
 		return;
 
 	for (; addr < end; addr = next) {
@@ -476,9 +475,8 @@  int kasan_add_zero_shadow(void *start, unsigned long size)
 	shadow_start = kasan_mem_to_shadow(start);
 	shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
 
-	if (WARN_ON((unsigned long)start %
-			(KASAN_GRANULE_SIZE * PAGE_SIZE)) ||
-	    WARN_ON(size % (KASAN_GRANULE_SIZE * PAGE_SIZE)))
+	if (WARN_ON((unsigned long)start % KASAN_GRANULE_PAGE) ||
+	    WARN_ON(size % KASAN_GRANULE_PAGE))
 		return -EINVAL;
 
 	ret = kasan_populate_early_shadow(shadow_start, shadow_end);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index c31e2c739301..1865bb92d47a 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -7,6 +7,7 @@ 
 
 #define KASAN_GRANULE_SIZE	(1UL << KASAN_SHADOW_SCALE_SHIFT)
 #define KASAN_GRANULE_MASK	(KASAN_GRANULE_SIZE - 1)
+#define KASAN_GRANULE_PAGE	(KASAN_GRANULE_SIZE << PAGE_SHIFT)
 
 #define KASAN_TAG_KERNEL	0xFF /* native kernel pointers tag */
 #define KASAN_TAG_INVALID	0xFE /* inaccessible memory tag */
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index ca0cc4c31454..1fadd4930d54 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -161,7 +161,7 @@  static int __meminit kasan_mem_notifier(struct notifier_block *nb,
 	shadow_end = shadow_start + shadow_size;
 
 	if (WARN_ON(mem_data->nr_pages % KASAN_GRANULE_SIZE) ||
-		WARN_ON(start_kaddr % (KASAN_GRANULE_SIZE << PAGE_SHIFT)))
+		WARN_ON(start_kaddr % KASAN_GRANULE_PAGE))
 		return NOTIFY_BAD;
 
 	switch (action) {
@@ -432,22 +432,20 @@  void kasan_release_vmalloc(unsigned long start, unsigned long end,
 	unsigned long region_start, region_end;
 	unsigned long size;
 
-	region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE);
-	region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE);
+	region_start = ALIGN(start, KASAN_GRANULE_PAGE);
+	region_end = ALIGN_DOWN(end, KASAN_GRANULE_PAGE);
 
-	free_region_start = ALIGN(free_region_start,
-				  PAGE_SIZE * KASAN_GRANULE_SIZE);
+	free_region_start = ALIGN(free_region_start, KASAN_GRANULE_PAGE);
 
 	if (start != region_start &&
 	    free_region_start < region_start)
-		region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE;
+		region_start -= KASAN_GRANULE_PAGE;
 
-	free_region_end = ALIGN_DOWN(free_region_end,
-				     PAGE_SIZE * KASAN_GRANULE_SIZE);
+	free_region_end = ALIGN_DOWN(free_region_end, KASAN_GRANULE_PAGE);
 
 	if (end != region_end &&
 	    free_region_end > region_end)
-		region_end += PAGE_SIZE * KASAN_GRANULE_SIZE;
+		region_end += KASAN_GRANULE_PAGE;
 
 	shadow_start = kasan_mem_to_shadow((void *)region_start);
 	shadow_end = kasan_mem_to_shadow((void *)region_end);