2007-10-15 22:25:06 +02:00
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2009-04-19 11:04:26 +02:00
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2005-04-16 15:20:36 -07:00
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2014-04-28 16:26:18 +09:00
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2005-04-16 15:20:36 -07:00
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2007-12-07 21:04:30 +09:00
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2005-04-16 15:20:36 -07:00
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2014-04-28 16:26:18 +09:00
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2005-04-16 15:20:36 -07:00
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2007-09-15 08:55:39 +02:00
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2005-04-16 15:20:36 -07:00
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2013-06-30 17:09:28 +08:00
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2005-04-16 15:20:36 -07:00
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2007-12-07 21:04:30 +09:00
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2005-04-16 15:20:36 -07:00
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2014-04-28 16:26:18 +09:00
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2005-04-16 15:20:36 -07:00
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2012-01-08 21:54:43 +01:00
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2005-09-23 08:42:11 +04:00
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2006-07-01 09:58:02 +02:00
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2005-09-23 08:42:11 +04:00
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2005-04-16 15:20:36 -07:00
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2009-04-19 11:04:26 +02:00
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2008-11-21 21:50:02 +01:00
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2008-05-14 21:30:29 -04:00
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2009-04-19 11:04:26 +02:00
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2008-11-21 21:50:02 +01:00
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2007-10-15 22:25:06 +02:00
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2005-04-16 15:20:36 -07:00
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2009-06-17 16:28:08 -07:00
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kasan: add kernel address sanitizer infrastructure
Kernel Address sanitizer (KASan) is a dynamic memory error detector. It
provides fast and comprehensive solution for finding use-after-free and
out-of-bounds bugs.
KASAN uses compile-time instrumentation for checking every memory access,
therefore GCC > v4.9.2 required. v4.9.2 almost works, but has issues with
putting symbol aliases into the wrong section, which breaks kasan
instrumentation of globals.
This patch only adds infrastructure for kernel address sanitizer. It's
not available for use yet. The idea and some code was borrowed from [1].
Basic idea:
The main idea of KASAN is to use shadow memory to record whether each byte
of memory is safe to access or not, and use compiler's instrumentation to
check the shadow memory on each memory access.
Address sanitizer uses 1/8 of the memory addressable in kernel for shadow
memory and uses direct mapping with a scale and offset to translate a
memory address to its corresponding shadow address.
Here is function to translate address to corresponding shadow address:
unsigned long kasan_mem_to_shadow(unsigned long addr)
{
return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET;
}
where KASAN_SHADOW_SCALE_SHIFT = 3.
So for every 8 bytes there is one corresponding byte of shadow memory.
The following encoding used for each shadow byte: 0 means that all 8 bytes
of the corresponding memory region are valid for access; k (1 <= k <= 7)
means that the first k bytes are valid for access, and other (8 - k) bytes
are not; Any negative value indicates that the entire 8-bytes are
inaccessible. Different negative values used to distinguish between
different kinds of inaccessible memory (redzones, freed memory) (see
mm/kasan/kasan.h).
To be able to detect accesses to bad memory we need a special compiler.
Such compiler inserts a specific function calls (__asan_load*(addr),
__asan_store*(addr)) before each memory access of size 1, 2, 4, 8 or 16.
These functions check whether memory region is valid to access or not by
checking corresponding shadow memory. If access is not valid an error
printed.
Historical background of the address sanitizer from Dmitry Vyukov:
"We've developed the set of tools, AddressSanitizer (Asan),
ThreadSanitizer and MemorySanitizer, for user space. We actively use
them for testing inside of Google (continuous testing, fuzzing,
running prod services). To date the tools have found more than 10'000
scary bugs in Chromium, Google internal codebase and various
open-source projects (Firefox, OpenSSL, gcc, clang, ffmpeg, MySQL and
lots of others): [2] [3] [4].
The tools are part of both gcc and clang compilers.
We have not yet done massive testing under the Kernel AddressSanitizer
(it's kind of chicken and egg problem, you need it to be upstream to
start applying it extensively). To date it has found about 50 bugs.
Bugs that we've found in upstream kernel are listed in [5].
We've also found ~20 bugs in out internal version of the kernel. Also
people from Samsung and Oracle have found some.
[...]
As others noted, the main feature of AddressSanitizer is its
performance due to inline compiler instrumentation and simple linear
shadow memory. User-space Asan has ~2x slowdown on computational
programs and ~2x memory consumption increase. Taking into account that
kernel usually consumes only small fraction of CPU and memory when
running real user-space programs, I would expect that kernel Asan will
have ~10-30% slowdown and similar memory consumption increase (when we
finish all tuning).
I agree that Asan can well replace kmemcheck. We have plans to start
working on Kernel MemorySanitizer that finds uses of unitialized
memory. Asan+Msan will provide feature-parity with kmemcheck. As
others noted, Asan will unlikely replace debug slab and pagealloc that
can be enabled at runtime. Asan uses compiler instrumentation, so even
if it is disabled, it still incurs visible overheads.
Asan technology is easily portable to other architectures. Compiler
instrumentation is fully portable. Runtime has some arch-dependent
parts like shadow mapping and atomic operation interception. They are
relatively easy to port."
Comparison with other debugging features:
========================================
KMEMCHECK:
- KASan can do almost everything that kmemcheck can. KASan uses
compile-time instrumentation, which makes it significantly faster than
kmemcheck. The only advantage of kmemcheck over KASan is detection of
uninitialized memory reads.
Some brief performance testing showed that kasan could be
x500-x600 times faster than kmemcheck:
$ netperf -l 30
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
no debug: 87380 16384 16384 30.00 41624.72
kasan inline: 87380 16384 16384 30.00 12870.54
kasan outline: 87380 16384 16384 30.00 10586.39
kmemcheck: 87380 16384 16384 30.03 20.23
- Also kmemcheck couldn't work on several CPUs. It always sets
number of CPUs to 1. KASan doesn't have such limitation.
DEBUG_PAGEALLOC:
- KASan is slower than DEBUG_PAGEALLOC, but KASan works on sub-page
granularity level, so it able to find more bugs.
SLUB_DEBUG (poisoning, redzones):
- SLUB_DEBUG has lower overhead than KASan.
- SLUB_DEBUG in most cases are not able to detect bad reads,
KASan able to detect both reads and writes.
- In some cases (e.g. redzone overwritten) SLUB_DEBUG detect
bugs only on allocation/freeing of object. KASan catch
bugs right before it will happen, so we always know exact
place of first bad read/write.
[1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel
[2] https://code.google.com/p/address-sanitizer/wiki/FoundBugs
[3] https://code.google.com/p/thread-sanitizer/wiki/FoundBugs
[4] https://code.google.com/p/memory-sanitizer/wiki/FoundBugs
[5] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel#Trophies
Based on work by Andrey Konovalov.
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 14:39:17 -08:00
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2005-04-16 15:20:36 -07:00
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2008-11-21 21:50:02 +01:00
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2010-09-17 11:09:17 -04:00
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2005-04-16 15:20:36 -07:00
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2008-11-21 21:50:02 +01:00
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2005-04-16 15:20:36 -07:00
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2008-11-21 21:50:02 +01:00
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2005-04-16 15:20:36 -07:00
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2007-10-15 22:25:06 +02:00
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2005-04-16 15:20:36 -07:00
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2013-05-31 11:14:20 +01:00
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2013-02-12 15:03:37 -07:00
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kbuild: create an "include chroot" for DT bindings
The recent dtc+cpp support allows header files and C pre-processor
defines/macros to be used when compiling device tree files. These
headers will typically define various constants that are part of the
device tree bindings.
The original patch which set up the dtc+cpp include path only considered
using those headers from device tree files. However, most are also
useful for kernel code which needs to interpret the device tree.
In both the DT files and the kernel, I'd like to include the DT-related
headers in the same way, for example, <dt-bindings/gpio/tegra-gpio.h>.
That will simplify any text which discusses the DT header locations.
Creating a <dt-bindings/> for kernel source to use is as simple as
placing files into include/dt-bindings/.
However, when compiling DT files, the include path should be restricted
so that only the dt-bindings path is available; arbitrary kernel headers
shouldn't be exposed. For this reason, create a specific include
directory for use by dtc+cpp, and symlink dt-bindings from there to the
actual location of include/dt-bindings/. For want of a better location,
place this "include chroot" into the existing dts/ directory.
arch/*/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings
Some headers used by device tree files may not be useful to the kernel;
they may be used simply to aid in constructing the DT file (e.g. macros
to create a node), but not define any information that the kernel needs
to share. These may be placed directly into arch/*/boot/dts/ along with
the DT files themselves.
Acked-by: Michal Marek <mmarek@suse.cz>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
2013-02-20 13:39:41 -07:00
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2014-02-18 21:46:16 +00:00
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2013-02-12 15:03:37 -07:00
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2005-04-16 15:20:36 -07:00
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2014-08-19 16:34:20 +09:00
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2011-05-23 00:04:43 -04:00
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2011-07-31 14:45:40 -04:00
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2011-05-23 00:04:43 -04:00
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2011-07-31 14:45:40 -04:00
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2011-05-23 00:04:43 -04:00
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2011-07-31 14:45:40 -04:00
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2011-05-23 00:04:43 -04:00
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2011-07-31 14:45:40 -04:00
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2011-05-23 00:04:43 -04:00
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2005-04-16 15:20:36 -07:00
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2011-06-07 13:09:28 -04:00
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2005-04-16 15:20:36 -07:00
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2014-04-28 16:26:18 +09:00
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2005-04-16 15:20:36 -07:00
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2007-09-30 20:34:36 +02:00
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2005-04-16 15:20:36 -07:00
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2007-10-15 22:25:06 +02:00
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2014-04-28 16:26:18 +09:00
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2005-04-16 15:20:36 -07:00
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2011-03-31 15:47:55 +02:00
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2009-05-05 21:17:15 -07:00
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2005-04-16 15:20:36 -07:00
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2010-12-22 11:57:26 -08:00
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2013-06-13 11:53:09 +01:00
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2010-12-22 11:57:26 -08:00
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2015-03-30 14:39:08 +02:00
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2013-03-06 10:58:37 -07:00
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kbuild: Don't assume dts files live in arch/*/boot/dts
In commit b40b25ff (kbuild: always run gcc -E on *.dts, remove cmd_dtc_cpp),
dts building was changed to always use the C preprocessor. This meant
that the .dts file passed to dtc is not the original, but the
preprocessed one.
When compiling with a separate build directory (i.e., with O=), this
preprocessed file will not live in the same directory as the original.
When the .dts file includes .dtsi files, dtc will look for them in the
build directory, not in the source directory and compilation will fail.
The commit referenced above tried to fix this by passing arch/*/boot/dts
as an include path to dtc. However, for mips, the .dts files are not in
this directory, so dts compilation on mips breaks for some targets.
Instead of hardcoding this particular include path, this commit just
uses the directory of the .dts file that is being compiled, which
effectively restores the previous behaviour wrt includes. For most .dts
files, this path is just the same as the previous hardcoded
arch/*/boot/dts path.
This was tested on a mips (rt3052) and an arm (bcm2835) target.
Signed-off-by: Matthijs Kooijman <matthijs@stdin.nl>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
2013-05-08 12:59:04 +02:00
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2013-05-31 11:14:20 +01:00
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2005-04-16 15:20:36 -07:00
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2012-11-27 16:29:10 -07:00
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2013-05-31 11:14:20 +01:00
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2013-02-05 12:06:28 -07:00
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2009-01-04 22:46:16 +01:00
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2009-05-05 21:17:15 -07:00
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2009-10-13 22:22:46 +02:00
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2009-05-05 21:17:15 -07:00
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2009-12-28 19:38:27 +00:00
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2009-05-05 21:17:15 -07:00
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2009-01-04 22:46:16 +01:00
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2009-05-05 21:17:15 -07:00
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lib: add support for LZO-compressed kernels
This patch series adds generic support for creating and extracting
LZO-compressed kernel images, as well as support for using such images on
the x86 and ARM architectures, and support for creating and using
LZO-compressed initrd and initramfs images.
Russell King said:
: Testing on a Cortex A9 model:
: - lzo decompressor is 65% of the time gzip takes to decompress a kernel
: - lzo kernel is 9% larger than a gzip kernel
:
: which I'm happy to say confirms your figures when comparing the two.
:
: However, when comparing your new gzip code to the old gzip code:
: - new is 99% of the size of the old code
: - new takes 42% of the time to decompress than the old code
:
: What this means is that for a proper comparison, the results get even better:
: - lzo is 7.5% larger than the old gzip'd kernel image
: - lzo takes 28% of the time that the old gzip code took
:
: So the expense seems definitely worth the effort. The only reason I
: can think of ever using gzip would be if you needed the additional
: compression (eg, because you have limited flash to store the image.)
:
: I would argue that the default for ARM should therefore be LZO.
This patch:
The lzo compressor is worse than gzip at compression, but faster at
extraction. Here are some figures for an ARM board I'm working on:
Uncompressed size: 3.24Mo
gzip 1.61Mo 0.72s
lzo 1.75Mo 0.48s
So for a compression ratio that is still relatively close to gzip, it's
much faster to extract, at least in that case.
This part contains:
- Makefile routine to support lzo compression
- Fixes to the existing lzo compressor so that it can be used in
compressed kernels
- wrapper around the existing lzo1x_decompress, as it only extracts one
block at a time, while we need to extract a whole file here
- config dialog for kernel compression
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Tested-by: Wu Zhangjin <wuzhangjin@gmail.com>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Russell King <rmk@arm.linux.org.uk>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-08 14:42:42 -08:00
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2010-03-11 17:42:14 +08:00
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lib: add support for LZO-compressed kernels
This patch series adds generic support for creating and extracting
LZO-compressed kernel images, as well as support for using such images on
the x86 and ARM architectures, and support for creating and using
LZO-compressed initrd and initramfs images.
Russell King said:
: Testing on a Cortex A9 model:
: - lzo decompressor is 65% of the time gzip takes to decompress a kernel
: - lzo kernel is 9% larger than a gzip kernel
:
: which I'm happy to say confirms your figures when comparing the two.
:
: However, when comparing your new gzip code to the old gzip code:
: - new is 99% of the size of the old code
: - new takes 42% of the time to decompress than the old code
:
: What this means is that for a proper comparison, the results get even better:
: - lzo is 7.5% larger than the old gzip'd kernel image
: - lzo takes 28% of the time that the old gzip code took
:
: So the expense seems definitely worth the effort. The only reason I
: can think of ever using gzip would be if you needed the additional
: compression (eg, because you have limited flash to store the image.)
:
: I would argue that the default for ARM should therefore be LZO.
This patch:
The lzo compressor is worse than gzip at compression, but faster at
extraction. Here are some figures for an ARM board I'm working on:
Uncompressed size: 3.24Mo
gzip 1.61Mo 0.72s
lzo 1.75Mo 0.48s
So for a compression ratio that is still relatively close to gzip, it's
much faster to extract, at least in that case.
This part contains:
- Makefile routine to support lzo compression
- Fixes to the existing lzo compressor so that it can be used in
compressed kernels
- wrapper around the existing lzo1x_decompress, as it only extracts one
block at a time, while we need to extract a whole file here
- config dialog for kernel compression
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Tested-by: Wu Zhangjin <wuzhangjin@gmail.com>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Russell King <rmk@arm.linux.org.uk>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-08 14:42:42 -08:00
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2010-03-05 17:34:46 +01:00
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2013-07-08 16:01:46 -07:00
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2012-03-16 15:03:55 -06:00
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2011-01-12 17:01:22 -08:00
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