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22 Commits (51306806426d0ffa4f9b11e65447092ae7d57ee7)

Author SHA1 Message Date
Andrey Konovalov 76bc99e81a kasan: fix HW_TAGS boot parameters
The initially proposed KASAN command line parameters are redundant.

This change drops the complex "kasan.mode=off/prod/full" parameter and
adds a simpler kill switch "kasan=off/on" instead.  The new parameter
together with the already existing ones provides a cleaner way to
express the same set of features.

The full set of parameters with this change:

  kasan=off/on             - whether KASAN is enabled
  kasan.fault=report/panic - whether to only print a report or also panic
  kasan.stacktrace=off/on  - whether to collect alloc/free stack traces

Default values:

  kasan=on
  kasan.fault=report
  kasan.stacktrace=on  (if CONFIG_DEBUG_KERNEL=y)
  kasan.stacktrace=off (otherwise)

Link: https://linux-review.googlesource.com/id/Ib3694ed90b1e8ccac6cf77dfd301847af4aba7b8
Link: https://lkml.kernel.org/r/4e9c4a4bdcadc168317deb2419144582a9be6e61.1610736745.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-01-24 10:34:52 -08:00
Linus Torvalds 1375b9803e Merge branch 'akpm' (patches from Andrew)
Merge KASAN updates from Andrew Morton.

This adds a new hardware tag-based mode to KASAN.  The new mode is
similar to the existing software tag-based KASAN, but relies on arm64
Memory Tagging Extension (MTE) to perform memory and pointer tagging
(instead of shadow memory and compiler instrumentation).

By Andrey Konovalov and Vincenzo Frascino.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (60 commits)
  kasan: update documentation
  kasan, mm: allow cache merging with no metadata
  kasan: sanitize objects when metadata doesn't fit
  kasan: clarify comment in __kasan_kfree_large
  kasan: simplify assign_tag and set_tag calls
  kasan: don't round_up too much
  kasan, mm: rename kasan_poison_kfree
  kasan, mm: check kasan_enabled in annotations
  kasan: add and integrate kasan boot parameters
  kasan: inline (un)poison_range and check_invalid_free
  kasan: open-code kasan_unpoison_slab
  kasan: inline random_tag for HW_TAGS
  kasan: inline kasan_reset_tag for tag-based modes
  kasan: remove __kasan_unpoison_stack
  kasan: allow VMAP_STACK for HW_TAGS mode
  kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK
  kasan: introduce set_alloc_info
  kasan: rename get_alloc/free_info
  kasan: simplify quarantine_put call site
  kselftest/arm64: check GCR_EL1 after context switch
  ...
2020-12-22 13:38:17 -08:00
Linus Torvalds c45647f9f5 ARM updates for 5.11:
- Rework phys/virt translation
 - Add KASan support
 - Move DT out of linear map region
 - Use more PC-relative addressing in assembly
 - Remove FP emulation handling while in kernel mode
 - Link with '-z norelro'
 - remove old check for GCC <= 4.2 in ARM unwinder code
 - disable big endian if using clang's linker
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Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux

Pull ARM updates from Russell King:

 - Rework phys/virt translation

 - Add KASan support

 - Move DT out of linear map region

 - Use more PC-relative addressing in assembly

 - Remove FP emulation handling while in kernel mode

 - Link with '-z norelro'

 - remove old check for GCC <= 4.2 in ARM unwinder code

 - disable big endian if using clang's linker

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (46 commits)
  ARM: 9027/1: head.S: explicitly map DT even if it lives in the first physical section
  ARM: 9038/1: Link with '-z norelro'
  ARM: 9037/1: uncompress: Add OF_DT_MAGIC macro
  ARM: 9036/1: uncompress: Fix dbgadtb size parameter name
  ARM: 9035/1: uncompress: Add be32tocpu macro
  ARM: 9033/1: arm/smp: Drop the macro S(x,s)
  ARM: 9032/1: arm/mm: Convert PUD level pgtable helper macros into functions
  ARM: 9031/1: hyp-stub: remove unused .L__boot_cpu_mode_offset symbol
  ARM: 9044/1: vfp: use undef hook for VFP support detection
  ARM: 9034/1: __div64_32(): straighten up inline asm constraints
  ARM: 9030/1: entry: omit FP emulation for UND exceptions taken in kernel mode
  ARM: 9029/1: Make iwmmxt.S support Clang's integrated assembler
  ARM: 9028/1: disable KASAN in call stack capturing routines
  ARM: 9026/1: unwind: remove old check for GCC <= 4.2
  ARM: 9025/1: Kconfig: CPU_BIG_ENDIAN depends on !LD_IS_LLD
  ARM: 9024/1: Drop useless cast of "u64" to "long long"
  ARM: 9023/1: Spelling s/mmeory/memory/
  ARM: 9022/1: Change arch/arm/lib/mem*.S to use WEAK instead of .weak
  ARM: kvm: replace open coded VA->PA calculations with adr_l call
  ARM: head.S: use PC relative insn sequence to calculate PHYS_OFFSET
  ...
2020-12-22 13:34:27 -08:00
Andrey Konovalov 625d867347 kasan: update documentation
This change updates KASAN documentation to reflect the addition of boot
parameters and also reworks and clarifies some of the existing sections,
in particular: defines what a memory granule is, mentions quarantine,
makes Kunit section more readable.

Link: https://lkml.kernel.org/r/748daf013e17d925b0fe00c1c3b5dce726dd2430.1606162397.git.andreyknvl@google.com
Link: https://linux-review.googlesource.com/id/Ib1f83e91be273264b25f42b04448ac96b858849f
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-22 12:55:09 -08:00
Andrey Konovalov 948e32539f kasan: add documentation for hardware tag-based mode
Add documentation for hardware tag-based KASAN mode and also add some
clarifications for software tag-based mode.

Link: https://lkml.kernel.org/r/20ed1d387685e89fc31be068f890f070ef9fd5d5.1606161801.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-22 12:55:08 -08:00
Andrey Konovalov 1f600626b3 kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_*
This is a preparatory commit for the upcoming addition of a new hardware
tag-based (MTE-based) KASAN mode.

The new mode won't be using shadow memory, but will still use the concept
of memory granules.  Each memory granule maps to a single metadata entry:
8 bytes per one shadow byte for generic mode, 16 bytes per one shadow byte
for software tag-based mode, and 16 bytes per one allocation tag for
hardware tag-based mode.

Rename KASAN_SHADOW_SCALE_SIZE to KASAN_GRANULE_SIZE, and
KASAN_SHADOW_MASK to KASAN_GRANULE_MASK.

Also use MASK when used as a mask, otherwise use SIZE.

No functional changes.

Link: https://lkml.kernel.org/r/939b5754e47f528a6e6a6f28ffc5815d8d128033.1606161801.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-22 12:55:06 -08:00
Linus Torvalds ac73e3dc8a Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:

 - a few random little subsystems

 - almost all of the MM patches which are staged ahead of linux-next
   material. I'll trickle to post-linux-next work in as the dependents
   get merged up.

Subsystems affected by this patch series: kthread, kbuild, ide, ntfs,
ocfs2, arch, and mm (slab-generic, slab, slub, dax, debug, pagecache,
gup, swap, shmem, memcg, pagemap, mremap, hmm, vmalloc, documentation,
kasan, pagealloc, memory-failure, hugetlb, vmscan, z3fold, compaction,
oom-kill, migration, cma, page-poison, userfaultfd, zswap, zsmalloc,
uaccess, zram, and cleanups).

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (200 commits)
  mm: cleanup kstrto*() usage
  mm: fix fall-through warnings for Clang
  mm: slub: convert sysfs sprintf family to sysfs_emit/sysfs_emit_at
  mm: shmem: convert shmem_enabled_show to use sysfs_emit_at
  mm:backing-dev: use sysfs_emit in macro defining functions
  mm: huge_memory: convert remaining use of sprintf to sysfs_emit and neatening
  mm: use sysfs_emit for struct kobject * uses
  mm: fix kernel-doc markups
  zram: break the strict dependency from lzo
  zram: add stat to gather incompressible pages since zram set up
  zram: support page writeback
  mm/process_vm_access: remove redundant initialization of iov_r
  mm/zsmalloc.c: rework the list_add code in insert_zspage()
  mm/zswap: move to use crypto_acomp API for hardware acceleration
  mm/zswap: fix passing zero to 'PTR_ERR' warning
  mm/zswap: make struct kernel_param_ops definitions const
  userfaultfd/selftests: hint the test runner on required privilege
  userfaultfd/selftests: fix retval check for userfaultfd_open()
  userfaultfd/selftests: always dump something in modes
  userfaultfd: selftests: make __{s,u}64 format specifiers portable
  ...
2020-12-15 12:53:37 -08:00
Walter Wu 4784be284a kasan: update documentation for generic kasan
Generic KASAN also supports to record the last two workqueue stacks and
print them in KASAN report.  So that need to update documentation.

Link: https://lkml.kernel.org/r/20201203023037.30792-1-walter-zh.wu@mediatek.com
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Marco Elver <elver@google.com>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-15 12:13:42 -08:00
Andrew Klychkov 1a37e18bd4 Documentation: fix typos in dev-tools/kasan.rst
Documentation: dev-tools: kasan.rst: fix typos

Signed-off-by: Andrew Klychkov <andrew.a.klyckov@gmail.com>
Link: https://lore.kernel.org/r/20201129192928.GA5692@ak-VirtualBox
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-11-30 06:35:37 -07:00
Mauro Carvalho Chehab 32519c0326 docs: kasan.rst: add two missing blank lines
literal blocks should start and end with a blank line,
as otherwise the parser complains and may do the wrong
thing, as warned by Sphinx:

	Documentation/dev-tools/kasan.rst:298: WARNING: Literal block ends without a blank line; unexpected unindent.
	Documentation/dev-tools/kasan.rst:303: WARNING: Literal block ends without a blank line; unexpected unindent.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Link: https://lore.kernel.org/r/cd6c4280fe26b07f2c5e5ed2918e17e88bb03419.1603791716.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-10-28 11:26:10 -06:00
Linus Walleij 421015713b ARM: 9017/2: Enable KASan for ARM
This patch enables the kernel address sanitizer for ARM. XIP_KERNEL
has not been tested and is therefore not allowed for now.

Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: kasan-dev@googlegroups.com
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org> # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli <f.fainelli@gmail.com> # Brahma SoCs
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # i.MX6Q
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2020-10-27 12:11:11 +00:00
Patricia Alfonso 9ab5be9768 KASAN: Testing Documentation
Include documentation on how to test KASAN using CONFIG_TEST_KASAN_KUNIT
and CONFIG_TEST_KASAN_MODULE.

Signed-off-by: Patricia Alfonso <trishalfonso@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20200915035828.570483-5-davidgow@google.com
Link: https://lkml.kernel.org/r/20200910070331.3358048-5-davidgow@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-13 18:38:32 -07:00
Marco Elver 527f6750d9 kasan: remove mentions of unsupported Clang versions
Since the kernel now requires at least Clang 10.0.1, remove any mention of
old Clang versions and simplify the documentation.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200902225911.209899-7-ndesaulniers@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-13 18:38:26 -07:00
Walter Wu 9793b62663 kasan: update documentation for generic kasan
Generic KASAN will support to record the last two call_rcu() call stacks
and print them in KASAN report.  So that need to update documentation.

Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Link: http://lkml.kernel.org/r/20200601051111.1359-1-walter-zh.wu@mediatek.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-07 11:33:28 -07:00
Marco Elver ac4766be5e kasan: update required compiler versions in documentation
Updates the recently changed compiler requirements for KASAN.  In
particular, we require GCC >= 8.3.0, and add a note that Clang 11 supports
OOB detection of globals.

Fixes: 7b861a53e4 ("kasan: Bump required compiler version")
Fixes: acf7b0bf7d ("kasan: Fix required compiler version")
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Axtens <dja@axtens.net>
Link: http://lkml.kernel.org/r/20200629104157.3242503-2-elver@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-07 11:33:28 -07:00
Nick Hu ea01ce6732
kasan: Add riscv to KASAN documentation.
Add riscv to the KASAN documentation to mention that riscv
is supporting generic kasan now.

Signed-off-by: Nick Hu <nickhu@andestech.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-01-22 13:10:00 -08:00
Daniel Axtens 3c5c3cfb9e kasan: support backing vmalloc space with real shadow memory
Patch series "kasan: support backing vmalloc space with real shadow
memory", v11.

Currently, vmalloc space is backed by the early shadow page.  This means
that kasan is incompatible with VMAP_STACK.

This series provides a mechanism to back vmalloc space with real,
dynamically allocated memory.  I have only wired up x86, because that's
the only currently supported arch I can work with easily, but it's very
easy to wire up other architectures, and it appears that there is some
work-in-progress code to do this on arm64 and s390.

This has been discussed before in the context of VMAP_STACK:
 - https://bugzilla.kernel.org/show_bug.cgi?id=202009
 - https://lkml.org/lkml/2018/7/22/198
 - https://lkml.org/lkml/2019/7/19/822

In terms of implementation details:

Most mappings in vmalloc space are small, requiring less than a full
page of shadow space.  Allocating a full shadow page per mapping would
therefore be wasteful.  Furthermore, to ensure that different mappings
use different shadow pages, mappings would have to be aligned to
KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.

Instead, share backing space across multiple mappings.  Allocate a
backing page when a mapping in vmalloc space uses a particular page of
the shadow region.  This page can be shared by other vmalloc mappings
later on.

We hook in to the vmap infrastructure to lazily clean up unused shadow
memory.

Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that:

 - Turning on KASAN, inline instrumentation, without vmalloc, introuduces
   a 4.1x-4.2x slowdown in vmalloc operations.

 - Turning this on introduces the following slowdowns over KASAN:
     * ~1.76x slower single-threaded (test_vmalloc.sh performance)
     * ~2.18x slower when both cpus are performing operations
       simultaneously (test_vmalloc.sh sequential_test_order=1)

This is unfortunate but given that this is a debug feature only, not the
end of the world.  The benchmarks are also a stress-test for the vmalloc
subsystem: they're not indicative of an overall 2x slowdown!

This patch (of 4):

Hook into vmalloc and vmap, and dynamically allocate real shadow memory
to back the mappings.

Most mappings in vmalloc space are small, requiring less than a full
page of shadow space.  Allocating a full shadow page per mapping would
therefore be wasteful.  Furthermore, to ensure that different mappings
use different shadow pages, mappings would have to be aligned to
KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.

Instead, share backing space across multiple mappings.  Allocate a
backing page when a mapping in vmalloc space uses a particular page of
the shadow region.  This page can be shared by other vmalloc mappings
later on.

We hook in to the vmap infrastructure to lazily clean up unused shadow
memory.

To avoid the difficulties around swapping mappings around, this code
expects that the part of the shadow region that covers the vmalloc space
will not be covered by the early shadow page, but will be left unmapped.
This will require changes in arch-specific code.

This allows KASAN with VMAP_STACK, and may be helpful for architectures
that do not have a separate module space (e.g.  powerpc64, which I am
currently working on).  It also allows relaxing the module alignment
back to PAGE_SIZE.

Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that:

 - Turning on KASAN, inline instrumentation, without vmalloc, introuduces
   a 4.1x-4.2x slowdown in vmalloc operations.

 - Turning this on introduces the following slowdowns over KASAN:
     * ~1.76x slower single-threaded (test_vmalloc.sh performance)
     * ~2.18x slower when both cpus are performing operations
       simultaneously (test_vmalloc.sh sequential_test_order=3D1)

This is unfortunate but given that this is a debug feature only, not the
end of the world.

The full benchmark results are:

Performance

                              No KASAN      KASAN original x baseline  KASAN vmalloc x baseline    x KASAN

fix_size_alloc_test             662004            11404956      17.23       19144610      28.92       1.68
full_fit_alloc_test             710950            12029752      16.92       13184651      18.55       1.10
long_busy_list_alloc_test      9431875            43990172       4.66       82970178       8.80       1.89
random_size_alloc_test         5033626            23061762       4.58       47158834       9.37       2.04
fix_align_alloc_test           1252514            15276910      12.20       31266116      24.96       2.05
random_size_align_alloc_te     1648501            14578321       8.84       25560052      15.51       1.75
align_shift_alloc_test             147                 830       5.65           5692      38.72       6.86
pcpu_alloc_test                  80732              125520       1.55         140864       1.74       1.12
Total Cycles              119240774314        763211341128       6.40  1390338696894      11.66       1.82

Sequential, 2 cpus

                              No KASAN      KASAN original x baseline  KASAN vmalloc x baseline    x KASAN

fix_size_alloc_test            1423150            14276550      10.03       27733022      19.49       1.94
full_fit_alloc_test            1754219            14722640       8.39       15030786       8.57       1.02
long_busy_list_alloc_test     11451858            52154973       4.55      107016027       9.34       2.05
random_size_alloc_test         5989020            26735276       4.46       68885923      11.50       2.58
fix_align_alloc_test           2050976            20166900       9.83       50491675      24.62       2.50
random_size_align_alloc_te     2858229            17971700       6.29       38730225      13.55       2.16
align_shift_alloc_test             405                6428      15.87          26253      64.82       4.08
pcpu_alloc_test                 127183              151464       1.19         216263       1.70       1.43
Total Cycles               54181269392        308723699764       5.70   650772566394      12.01       2.11
fix_size_alloc_test            1420404            14289308      10.06       27790035      19.56       1.94
full_fit_alloc_test            1736145            14806234       8.53       15274301       8.80       1.03
long_busy_list_alloc_test     11404638            52270785       4.58      107550254       9.43       2.06
random_size_alloc_test         6017006            26650625       4.43       68696127      11.42       2.58
fix_align_alloc_test           2045504            20280985       9.91       50414862      24.65       2.49
random_size_align_alloc_te     2845338            17931018       6.30       38510276      13.53       2.15
align_shift_alloc_test             472                3760       7.97           9656      20.46       2.57
pcpu_alloc_test                 118643              132732       1.12         146504       1.23       1.10
Total Cycles               54040011688        309102805492       5.72   651325675652      12.05       2.11

[dja@axtens.net: fixups]
  Link: http://lkml.kernel.org/r/20191120052719.7201-1-dja@axtens.net
Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D202009
Link: http://lkml.kernel.org/r/20191031093909.9228-2-dja@axtens.net
Signed-off-by: Mark Rutland <mark.rutland@arm.com> [shadow rework]
Signed-off-by: Daniel Axtens <dja@axtens.net>
Co-developed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-01 12:59:05 -08:00
Vlastimil Babka 0fe9a448a0 mm, page_owner: decouple freeing stack trace from debug_pagealloc
Commit 8974558f49 ("mm, page_owner, debug_pagealloc: save and dump
freeing stack trace") enhanced page_owner to also store freeing stack
trace, when debug_pagealloc is also enabled.  KASAN would also like to
do this [1] to improve error reports to debug e.g. UAF issues.

Kirill has suggested that the freeing stack trace saving should be also
possible to be enabled separately from KASAN or debug_pagealloc, i.e.
with an extra boot option.  Qian argued that we have enough options
already, and avoiding the extra overhead is not worth the complications
in the case of a debugging option.  Kirill noted that the extra stack
handle in struct page_owner requires 0.1% of memory.

This patch therefore enables free stack saving whenever page_owner is
enabled, regardless of whether debug_pagealloc or KASAN is also enabled.
KASAN kernels booted with page_owner=on will thus benefit from the
improved error reports.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=203967

[vbabka@suse.cz: v3]
  Link: http://lkml.kernel.org/r/20191007091808.7096-3-vbabka@suse.cz
Link: http://lkml.kernel.org/r/20190930122916.14969-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Qian Cai <cai@lca.pw>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-10-14 15:04:00 -07:00
Andrey Konovalov b3b0e6accb kasan: update documentation
This patch updates KASAN documentation to reflect the addition of the new
tag-based mode.

Link: http://lkml.kernel.org/r/aabef9de317c54b8a3919a4946ce534c6576726a.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:44 -08:00
Mike Rapoport ad56b738c5 docs/vm: rename documentation files to .rst
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-04-16 14:18:15 -06:00
Jonathan Corbet 5512128f02 Merge branch 'dev-tools' into doc/4.9
Coalesce development-tool documents into a single directory and sphinxify
them.
2016-08-19 11:38:36 -06:00
Jonathan Corbet 2757aafad9 docs: sphinxify kasan.txt and move to dev-tools
No textual changes beyond formatting.

Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-08-18 17:41:45 -06:00