From: Ard Biesheuvel <ardb@kernel.org>
To: Lecopzer Chen <lecopzer@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mediatek@lists.infradead.org, yj.chiang@mediatek.com,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Andrey Konovalov <andreyknvl@google.com>,
Mark Brown <broonie@kernel.org>,
Guenter Roeck <linux@roeck-us.net>,
Mike Rapoport <rppt@kernel.org>,
Tyler Hicks <tyhicks@linux.microsoft.com>,
Robin Murphy <robin.murphy@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Lecopzer Chen <lecopzer.chen@mediatek.com>
Subject: Re: [PATCH v2 1/4] arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC
Date: Wed, 3 Feb 2021 19:37:18 +0100 [thread overview]
Message-ID: <CAMj1kXEMOeCZTvNqPPk-uL5iA7hx7SFPwkq3Oz3yYefn=tVnPQ@mail.gmail.com> (raw)
In-Reply-To: <20210109103252.812517-2-lecopzer@gmail.com>
On Sat, 9 Jan 2021 at 11:33, Lecopzer Chen <lecopzer@gmail.com> wrote:
>
> Linux support KAsan for VMALLOC since commit 3c5c3cfb9ef4da9
> ("kasan: support backing vmalloc space with real shadow memory")
>
> Like how the MODULES_VADDR does now, just not to early populate
> the VMALLOC_START between VMALLOC_END.
> similarly, the kernel code mapping is now in the VMALLOC area and
> should keep these area populated.
>
> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
This commit log text is a bit hard to follow. You are saying that the
vmalloc region is *not* backed with zero shadow or any default mapping
at all, right, and everything gets allocated on demand, just like is
the case for modules?
> ---
> arch/arm64/mm/kasan_init.c | 23 ++++++++++++++++++-----
> 1 file changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
> index d8e66c78440e..39b218a64279 100644
> --- a/arch/arm64/mm/kasan_init.c
> +++ b/arch/arm64/mm/kasan_init.c
> @@ -214,6 +214,7 @@ static void __init kasan_init_shadow(void)
> {
> u64 kimg_shadow_start, kimg_shadow_end;
> u64 mod_shadow_start, mod_shadow_end;
> + u64 vmalloc_shadow_start, vmalloc_shadow_end;
> phys_addr_t pa_start, pa_end;
> u64 i;
>
> @@ -223,6 +224,9 @@ static void __init kasan_init_shadow(void)
> mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
> mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
>
> + vmalloc_shadow_start = (u64)kasan_mem_to_shadow((void *)VMALLOC_START);
> + vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END);
> +
This and the below seems overly complicated, given that VMALLOC_START
== MODULES_END. Can we simplify this?
> /*
> * We are going to perform proper setup of shadow memory.
> * At first we should unmap early shadow (clear_pgds() call below).
> @@ -241,12 +245,21 @@ static void __init kasan_init_shadow(void)
>
> kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
> (void *)mod_shadow_start);
> - kasan_populate_early_shadow((void *)kimg_shadow_end,
> - (void *)KASAN_SHADOW_END);
> + if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
> + kasan_populate_early_shadow((void *)vmalloc_shadow_end,
> + (void *)KASAN_SHADOW_END);
> + if (vmalloc_shadow_start > mod_shadow_end)
> + kasan_populate_early_shadow((void *)mod_shadow_end,
> + (void *)vmalloc_shadow_start);
> +
> + } else {
> + kasan_populate_early_shadow((void *)kimg_shadow_end,
> + (void *)KASAN_SHADOW_END);
> + if (kimg_shadow_start > mod_shadow_end)
> + kasan_populate_early_shadow((void *)mod_shadow_end,
> + (void *)kimg_shadow_start);
> + }
>
> - if (kimg_shadow_start > mod_shadow_end)
> - kasan_populate_early_shadow((void *)mod_shadow_end,
> - (void *)kimg_shadow_start);
>
> for_each_mem_range(i, &pa_start, &pa_end) {
> void *start = (void *)__phys_to_virt(pa_start);
> --
> 2.25.1
>
next prev parent reply other threads:[~2021-02-03 18:38 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 10:32 [PATCH v2 0/4] arm64: kasan: support CONFIG_KASAN_VMALLOC Lecopzer Chen
2021-01-09 10:32 ` [PATCH v2 1/4] arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC Lecopzer Chen
2021-02-03 18:37 ` Ard Biesheuvel [this message]
2021-02-04 6:21 ` Lecopzer Chen
2021-02-04 12:45 ` Will Deacon
2021-02-04 14:46 ` Lecopzer Chen
2021-02-04 15:01 ` Will Deacon
2021-02-04 16:37 ` Lecopzer Chen
2021-02-05 17:18 ` Will Deacon
2021-02-05 17:30 ` Andrey Konovalov
2021-02-05 17:43 ` Will Deacon
2021-02-05 20:50 ` Andrey Konovalov
2021-02-05 18:10 ` Lecopzer Chen
2021-01-09 10:32 ` [PATCH v2 2/4] arm64: kasan: abstract _text and _end to KERNEL_START/END Lecopzer Chen
2021-02-04 12:46 ` Will Deacon
2021-02-04 14:51 ` Lecopzer Chen
2021-02-04 14:55 ` Will Deacon
2021-02-04 16:06 ` Lecopzer Chen
2021-02-05 17:02 ` Will Deacon
2021-01-09 10:32 ` [PATCH v2 3/4] arm64: Kconfig: support CONFIG_KASAN_VMALLOC Lecopzer Chen
2021-01-09 10:32 ` [PATCH v2 4/4] arm64: kaslr: support randomized module area with KASAN_VMALLOC Lecopzer Chen
2021-01-27 23:04 ` Will Deacon
2021-01-28 8:53 ` Lecopzer Chen
2021-01-28 20:26 ` Will Deacon
2021-01-21 10:19 ` [PATCH v2 0/4] arm64: kasan: support CONFIG_KASAN_VMALLOC Lecopzer Chen
2021-01-21 17:44 ` Andrey Konovalov
2021-01-22 19:05 ` Will Deacon
2021-02-03 18:31 ` Ard Biesheuvel
2021-02-04 12:49 ` Will Deacon
2021-02-04 15:53 ` Lecopzer Chen
2021-02-04 17:57 ` Will Deacon
2021-02-04 18:41 ` Lecopzer Chen
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