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Date: Sun, 18 Mar 2018 12:13:50 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: Abbott Liu <liuwenliang@...wei.com>, linux@...linux.org.uk,
aryabinin@...tuozzo.com, marc.zyngier@....com,
kstewart@...uxfoundation.org, gregkh@...uxfoundation.org,
akpm@...ux-foundation.org, afzal.mohd.ma@...il.com,
alexander.levin@...izon.com
Cc: glider@...gle.com, dvyukov@...gle.com, christoffer.dall@...aro.org,
linux@...musvillemoes.dk, mawilcox@...rosoft.com,
pombredanne@...b.com, ard.biesheuvel@...aro.org,
vladimir.murzin@....com, nicolas.pitre@...aro.org,
tglx@...utronix.de, thgarnie@...gle.com, dhowells@...hat.com,
keescook@...omium.org, arnd@...db.de, geert@...ux-m68k.org,
tixy@...aro.org, mark.rutland@....com, james.morse@....com,
zhichao.huang@...aro.org, jinb.park7@...il.com, labbott@...hat.com,
philip@....systems, grygorii.strashko@...aro.org,
catalin.marinas@....com, opendmb@...il.com,
kirill.shutemov@...ux.intel.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
kasan-dev@...glegroups.com, kvmarm@...ts.cs.columbia.edu,
linux-mm@...ck.org
Subject: Re: [PATCH v2 0/7] KASan for arm
Hi Abbott,
On 03/18/2018 05:53 AM, Abbott Liu wrote:
> Changelog:
> v2 - v1
> - Fixed some compiling error which happens on changing kernel compression
> mode to lzma/xz/lzo/lz4.
> ---Reported by: Florian Fainelli <f.fainelli@...il.com>,
> Russell King - ARM Linux <linux@...linux.org.uk>
> - Fixed a compiling error cause by some older arm instruction set(armv4t)
> don't suppory movw/movt which is reported by kbuild.
> - Changed the pte flag from _L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN to
> pgprot_val(PAGE_KERNEL).
> ---Reported by: Russell King - ARM Linux <linux@...linux.org.uk>
> - Moved Enable KASan patch as the last one.
> ---Reported by: Florian Fainelli <f.fainelli@...il.com>,
> Russell King - ARM Linux <linux@...linux.org.uk>
> - Moved the definitions of cp15 registers from
> arch/arm/include/asm/kvm_hyp.h to arch/arm/include/asm/cp15.h.
> ---Asked by: Mark Rutland <mark.rutland@....com>
> - Merge the following commits into the commit
> Define the virtual space of KASan's shadow region:
> 1) Define the virtual space of KASan's shadow region;
> 2) Avoid cleaning the KASan shadow area's mapping table;
> 3) Add KASan layout;
> - Merge the following commits into the commit
> Initialize the mapping of KASan shadow memory:
> 1) Initialize the mapping of KASan shadow memory;
> 2) Add support arm LPAE;
> 3) Don't need to map the shadow of KASan's shadow memory;
> ---Reported by: Russell King - ARM Linux <linux@...linux.org.uk>
> 4) Change mapping of kasan_zero_page int readonly.
Thanks for posting these patches! Just FWIW, you cannot quite add
someone's Tested-by for a patch series that was just resubmitted given
the differences with v1. I just gave it a spin on a Cortex-A5 (no LPAE)
and it looks like test_kasan.ko is passing, great job!
>
> Hi,all:
> These patches add arch specific code for kernel address sanitizer
> (see Documentation/kasan.txt).
>
> 1/8 of kernel addresses reserved for shadow memory. There was no
> big enough hole for this, so virtual addresses for shadow were
> stolen from user space.
>
> At early boot stage the whole shadow region populated with just
> one physical page (kasan_zero_page). Later, this page reused
> as readonly zero shadow for some memory that KASan currently
> don't track (vmalloc).
>
> After mapping the physical memory, pages for shadow memory are
> allocated and mapped.
>
> KASan's stack instrumentation significantly increases stack's
> consumption, so CONFIG_KASAN doubles THREAD_SIZE.
>
> Functions like memset/memmove/memcpy do a lot of memory accesses.
> If bad pointer passed to one of these function it is important
> to catch this. Compiler's instrumentation cannot do this since
> these functions are written in assembly.
>
> KASan replaces memory functions with manually instrumented variants.
> Original functions declared as weak symbols so strong definitions
> in mm/kasan/kasan.c could replace them. Original functions have aliases
> with '__' prefix in name, so we could call non-instrumented variant
> if needed.
>
> Some files built without kasan instrumentation (e.g. mm/slub.c).
> Original mem* function replaced (via #define) with prefixed variants
> to disable memory access checks for such files.
>
> On arm LPAE architecture, the mapping table of KASan shadow memory(if
> PAGE_OFFSET is 0xc0000000, the KASan shadow memory's virtual space is
> 0xb6e000000~0xbf000000) can't be filled in do_translation_fault function,
> because kasan instrumentation maybe cause do_translation_fault function
> accessing KASan shadow memory. The accessing of KASan shadow memory in
> do_translation_fault function maybe cause dead circle. So the mapping table
> of KASan shadow memory need be copyed in pgd_alloc function.
>
>
> Most of the code comes from:
> https://github.com/aryabinin/linux/commit/0b54f17e70ff50a902c4af05bb92716eb95acefe
>
> These patches are tested on vexpress-ca15, vexpress-ca9
>
>
>
> Cc: Andrey Ryabinin <a.ryabinin@...sung.com>
> Tested-by: Abbott Liu <liuwenliang@...wei.com>
> Signed-off-by: Abbott Liu <liuwenliang@...wei.com>
>
> Abbott Liu (3):
> 2 1-byte checks more safer for memory_is_poisoned_16
> Add TTBR operator for kasan_init
> Define the virtual space of KASan's shadow region
>
> Andrey Ryabinin (4):
> Disable instrumentation for some code
> Replace memory function for kasan
> Initialize the mapping of KASan shadow memory
> Enable KASan for arm
>
> arch/arm/Kconfig | 1 +
> arch/arm/boot/compressed/Makefile | 1 +
> arch/arm/boot/compressed/decompress.c | 2 +
> arch/arm/boot/compressed/libfdt_env.h | 2 +
> arch/arm/include/asm/cp15.h | 104 ++++++++++++
> arch/arm/include/asm/kasan.h | 23 +++
> arch/arm/include/asm/kasan_def.h | 52 ++++++
> arch/arm/include/asm/kvm_hyp.h | 52 ------
> arch/arm/include/asm/memory.h | 5 +
> arch/arm/include/asm/pgalloc.h | 7 +-
> arch/arm/include/asm/string.h | 17 ++
> arch/arm/include/asm/thread_info.h | 4 +
> arch/arm/kernel/entry-armv.S | 5 +-
> arch/arm/kernel/entry-common.S | 6 +-
> arch/arm/kernel/head-common.S | 7 +-
> arch/arm/kernel/setup.c | 2 +
> arch/arm/kernel/unwind.c | 3 +-
> arch/arm/kvm/hyp/cp15-sr.c | 12 +-
> arch/arm/kvm/hyp/switch.c | 6 +-
> arch/arm/lib/memcpy.S | 3 +
> arch/arm/lib/memmove.S | 5 +-
> arch/arm/lib/memset.S | 3 +
> arch/arm/mm/Makefile | 3 +
> arch/arm/mm/init.c | 6 +
> arch/arm/mm/kasan_init.c | 290 ++++++++++++++++++++++++++++++++++
> arch/arm/mm/mmu.c | 7 +-
> arch/arm/mm/pgd.c | 14 ++
> arch/arm/vdso/Makefile | 2 +
> mm/kasan/kasan.c | 24 ++-
> 29 files changed, 588 insertions(+), 80 deletions(-)
> create mode 100644 arch/arm/include/asm/kasan.h
> create mode 100644 arch/arm/include/asm/kasan_def.h
> create mode 100644 arch/arm/mm/kasan_init.c
>
--
Florian
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