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Message-ID: <CAG_fn=U3uSm3-dDoDJ6RG2-p4SmcG0sB0z3yjX4Xypf7U67qVg@mail.gmail.com>
Date: Wed, 18 Nov 2020 16:36:10 +0100
From: Alexander Potapenko <glider@...gle.com>
To: Andrey Konovalov <andreyknvl@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Marco Elver <elver@...gle.com>,
Evgenii Stepanov <eugenis@...gle.com>,
Branislav Rankov <Branislav.Rankov@....com>,
Kevin Brodsky <kevin.brodsky@....com>,
kasan-dev <kasan-dev@...glegroups.com>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux Memory Management List <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH mm v10 09/42] kasan: define KASAN_MEMORY_PER_SHADOW_PAGE
On Fri, Nov 13, 2020 at 11:16 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> Define KASAN_MEMORY_PER_SHADOW_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT),
> which is the same as (KASAN_GRANULE_SIZE * PAGE_SIZE) for software modes
> that use shadow memory, and use it across KASAN code to simplify it.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> Reviewed-by: Marco Elver <elver@...gle.com>
Reviewed-by: Alexander Potapenko <glider@...gle.com>
> ---
> Change-Id: I0b627b24187d06c8b9bb2f1d04d94b3d06945e73
> ---
> mm/kasan/init.c | 10 ++++------
> mm/kasan/kasan.h | 2 ++
> mm/kasan/shadow.c | 16 +++++++---------
> 3 files changed, 13 insertions(+), 15 deletions(-)
>
> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> index 1a71eaa8c5f9..bc0ad208b3a7 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_MEMORY_PER_SHADOW_PAGE) ||
> + WARN_ON(size % KASAN_MEMORY_PER_SHADOW_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_MEMORY_PER_SHADOW_PAGE) ||
> + WARN_ON(size % KASAN_MEMORY_PER_SHADOW_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 53b095f56f28..eec88bf28c64 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -8,6 +8,8 @@
> #define KASAN_GRANULE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
> #define KASAN_GRANULE_MASK (KASAN_GRANULE_SIZE - 1)
>
> +#define KASAN_MEMORY_PER_SHADOW_PAGE (KASAN_GRANULE_SIZE << PAGE_SHIFT)
> +
> #define KASAN_TAG_KERNEL 0xFF /* native kernel pointers tag */
> #define KASAN_TAG_INVALID 0xFE /* inaccessible memory tag */
> #define KASAN_TAG_MAX 0xFD /* maximum value for random tags */
> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
> index 4264bfbdca1a..80522d2c447b 100644
> --- a/mm/kasan/shadow.c
> +++ b/mm/kasan/shadow.c
> @@ -174,7 +174,7 @@ 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_MEMORY_PER_SHADOW_PAGE))
> return NOTIFY_BAD;
>
> switch (action) {
> @@ -445,22 +445,20 @@ 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_MEMORY_PER_SHADOW_PAGE);
> + region_end = ALIGN_DOWN(end, KASAN_MEMORY_PER_SHADOW_PAGE);
>
> - free_region_start = ALIGN(free_region_start,
> - PAGE_SIZE * KASAN_GRANULE_SIZE);
> + free_region_start = ALIGN(free_region_start, KASAN_MEMORY_PER_SHADOW_PAGE);
>
> if (start != region_start &&
> free_region_start < region_start)
> - region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE;
> + region_start -= KASAN_MEMORY_PER_SHADOW_PAGE;
>
> - free_region_end = ALIGN_DOWN(free_region_end,
> - PAGE_SIZE * KASAN_GRANULE_SIZE);
> + free_region_end = ALIGN_DOWN(free_region_end, KASAN_MEMORY_PER_SHADOW_PAGE);
>
> if (end != region_end &&
> free_region_end > region_end)
> - region_end += PAGE_SIZE * KASAN_GRANULE_SIZE;
> + region_end += KASAN_MEMORY_PER_SHADOW_PAGE;
>
> shadow_start = kasan_mem_to_shadow((void *)region_start);
> shadow_end = kasan_mem_to_shadow((void *)region_end);
> --
> 2.29.2.299.gdc1121823c-goog
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
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