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  1. 29 5月, 2016 1 次提交
    • G
      <linux/hash.h>: Add support for architecture-specific functions · 468a9428
      由 George Spelvin 提交于 
      This is just the infrastructure; there are no users yet.

This is modelled on CONFIG_ARCH_RANDOM; a CONFIG_ symbol declares
the existence of <asm/hash.h>.

That file may define its own versions of various functions, and define
HAVE_* symbols (no CONFIG_ prefix!) to suppress the generic ones.

Included is a self-test (in lib/test_hash.c) that verifies the basics.
It is NOT in general required that the arch-specific functions compute
the same thing as the generic, but if a HAVE_* symbol is defined with
the value 1, then equality is tested.
Signed-off-by: NGeorge Spelvin <linux@sciencehorizons.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Philippe De Muyter <phdm@macq.eu>
Cc: linux-m68k@lists.linux-m68k.org
Cc: Alistair Francis <alistai@xilinx.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: uclinux-h8-devel@lists.sourceforge.jp
      468a9428
  3. 23 3月, 2016 2 次提交
    • H
      parisc,metag: Implement CONFIG_DEBUG_STACK_USAGE option · 6c31da34
      由 Helge Deller 提交于 
      On parisc and metag the stack grows upwards, so for those we need to
scan the stack downwards in order to calculate how much stack a process
has used.

Tested on a 64bit parisc kernel.
Signed-off-by: NHelge Deller <deller@gmx.de>
      6c31da34
    • D
      kernel: add kcov code coverage · 5c9a8750
      由 Dmitry Vyukov 提交于 
      kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing).  Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system.  A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/).  However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.

kcov does not aim to collect as much coverage as possible.  It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g.  scheduler, locking).

Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes.  Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch).  I've
dropped the second mode for simplicity.

This patch adds the necessary support on kernel side.  The complimentary
compiler support was added in gcc revision 231296.

We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:

  https://github.com/google/syzkaller/wiki/Found-Bugs

We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation".  For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.

Why not gcov.  Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat.  A
typical coverage can be just a dozen of basic blocks (e.g.  an invalid
input).  In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M).  Cost of
kcov depends only on number of executed basic blocks/edges.  On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.

kcov exposes kernel PCs and control flow to user-space which is
insecure.  But debugfs should not be mapped as user accessible.

Based on a patch by Quentin Casasnovas.

[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Drysdale <drysdale@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5c9a8750
  5. 02 3月, 2016 1 次提交
    • T
      cpu/hotplug: Make target state writeable · 757c989b
      由 Thomas Gleixner 提交于 
      Make it possible to write a target state to the per cpu state file, so we can
switch between states.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.022814799@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      757c989b
  7. 29 2月, 2016 1 次提交
  9. 20 2月, 2016 1 次提交
  11. 10 2月, 2016 1 次提交
    • T
      workqueue: implement "workqueue.debug_force_rr_cpu" debug feature · f303fccb
      由 Tejun Heo 提交于 
      Workqueue used to guarantee local execution for work items queued
without explicit target CPU.  The guarantee is gone now which can
break some usages in subtle ways.  To flush out those cases, this
patch implements a debug feature which forces round-robin CPU
selection for all such work items.

The debug feature defaults to off and can be enabled with a kernel
parameter.  The default can be flipped with a debug config option.

If you hit this commit during bisection, please refer to 041bd12e
("Revert "workqueue: make sure delayed work run in local cpu"") for
more information and ping me.
Signed-off-by: NTejun Heo <tj@kernel.org>
      f303fccb
  13. 21 1月, 2016 2 次提交
  15. 17 1月, 2016 1 次提交
  17. 16 1月, 2016 1 次提交
    • K
      page-flags: introduce page flags policies wrt compound pages · 95ad9755
      由 Kirill A. Shutemov 提交于 
      This patch adds a third argument to macros which create function
definitions for page flags.  This argument defines how page-flags
helpers behave on compound functions.

For now we define four policies:

 - PF_ANY: the helper function operates on the page it gets, regardless
   if it's non-compound, head or tail.

 - PF_HEAD: the helper function operates on the head page of the
   compound page if it gets tail page.

 - PF_NO_TAIL: only head and non-compond pages are acceptable for this
   helper function.

 - PF_NO_COMPOUND: only non-compound pages are acceptable for this
   helper function.

For now we use policy PF_ANY for all helpers, which matches current
behaviour.

We do not enforce the policy for TESTPAGEFLAG, because we have flags
checked for random pages all over the kernel.  Noticeable exception to
this is PageTransHuge() which triggers VM_BUG_ON() for tail page.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      95ad9755
  19. 09 1月, 2016 2 次提交
    • D
      restrict /dev/mem to idle io memory ranges · 90a545e9
      由 Dan Williams 提交于 
      This effectively promotes IORESOURCE_BUSY to IORESOURCE_EXCLUSIVE
semantics by default.  If userspace really believes it is safe to access
the memory region it can also perform the extra step of disabling an
active driver.  This protects device address ranges with read side
effects and otherwise directs userspace to use the driver.

Persistent memory presents a large "mistake surface" to /dev/mem as now
accidental writes can corrupt a filesystem.

In general if a device driver is busily using a memory region it already
informs other parts of the kernel to not touch it via
request_mem_region().  /dev/mem should honor the same safety restriction
by default.  Debugging a device driver from userspace becomes more
difficult with this enabled.  Any application using /dev/mem or mmap of
sysfs pci resources will now need to perform the extra step of either:

1/ Disabling the driver, for example:

   echo <device id> > /dev/bus/<parent bus>/drivers/<driver name>/unbind

2/ Rebooting with "iomem=relaxed" on the command line

3/ Recompiling with CONFIG_IO_STRICT_DEVMEM=n

Traditional users of /dev/mem like dosemu are unaffected because the
first 1MB of memory is not subject to the IO_STRICT_DEVMEM restriction.
Legacy X configurations use /dev/mem to talk to graphics hardware, but
that functionality has since moved to kernel graphics drivers.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NIngo Molnar <mingo@redhat.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
      90a545e9
    • D
      arch: consolidate CONFIG_STRICT_DEVM in lib/Kconfig.debug · 21266be9
      由 Dan Williams 提交于 
      Let all the archs that implement devmem_is_allowed() opt-in to a common
definition of CONFIG_STRICT_DEVM in lib/Kconfig.debug.

Cc: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
[heiko: drop 'default y' for s390]
Acked-by: NIngo Molnar <mingo@redhat.com>
Suggested-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
      21266be9
  21. 22 12月, 2015 1 次提交
  23. 09 12月, 2015 1 次提交
    • T
      workqueue: implement lockup detector · 82607adc
      由 Tejun Heo 提交于 
      Workqueue stalls can happen from a variety of usage bugs such as
missing WQ_MEM_RECLAIM flag or concurrency managed work item
indefinitely staying RUNNING.  These stalls can be extremely difficult
to hunt down because the usual warning mechanisms can't detect
workqueue stalls and the internal state is pretty opaque.

To alleviate the situation, this patch implements workqueue lockup
detector.  It periodically monitors all worker_pools periodically and,
if any pool failed to make forward progress longer than the threshold
duration, triggers warning and dumps workqueue state as follows.

 BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s!
 Showing busy workqueues and worker pools:
 workqueue events: flags=0x0
   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256
     pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent
 workqueue events_power_efficient: flags=0x80
   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
     pending: check_lifetime, neigh_periodic_work
 workqueue cgroup_pidlist_destroy: flags=0x0
   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1
     pending: cgroup_pidlist_destroy_work_fn
 ...

The detection mechanism is controller through kernel parameter
workqueue.watchdog_thresh and can be updated at runtime through the
sysfs module parameter file.

v2: Decoupled from softlockup control knobs.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NDon Zickus <dzickus@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
      82607adc
  25. 02 12月, 2015 1 次提交
    • N
      net: add support for netdev notifier error injection · 02fff96a
      由 Nikolay Aleksandrov 提交于 
      This module allows to insert errors in some of netdevice's notifier
events. All network drivers use these notifiers to signal various events
and to check if they are allowed, e.g. PRECHANGEMTU and CHANGEMTU
afterwards. Until recently I had to run failure tests by injecting
a custom module, but now this infrastructure makes it trivial to test
these failure paths. Some of the recent bugs I fixed were found using
this module.
Here's an example:
 $ cd /sys/kernel/debug/notifier-error-inject/netdev
 $ echo -22 > actions/NETDEV_CHANGEMTU/error
 $ ip link set eth0 mtu 1024
 RTNETLINK answers: Invalid argument

CC: Akinobu Mita <akinobu.mita@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: netdev <netdev@vger.kernel.org>
Signed-off-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      02fff96a
  27. 07 11月, 2015 1 次提交
    • R
      test_printf: test printf family at runtime · 707cc728
      由 Rasmus Villemoes 提交于 
      This adds a simple module for testing the kernel's printf facilities.
Previously, some %p extensions have caused a wrong return value in case
the entire output didn't fit and/or been unusable in kasprintf().  This
should help catch such issues.  Also, it should help ensure that changes
to the formatting algorithms don't break anything.

I'm not sure if we have a struct dentry or struct file lying around at
boot time or if we can fake one, but most %p extensions should be
testable, as should the ordinary number and string formatting.

The nature of vararg functions means we can't use a more conventional
table-driven approach.

For now, this is mostly a skeleton; contributions are very
welcome. Some tests are/will be slightly annoying to write, since the
expected output depends on stuff like CONFIG_*, sizeof(long), runtime
values etc.
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Martin Kletzander <mkletzan@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      707cc728
  29. 23 10月, 2015 1 次提交
  31. 06 10月, 2015 1 次提交
  33. 03 8月, 2015 2 次提交
  35. 23 7月, 2015 1 次提交
  37. 20 7月, 2015 2 次提交
    • D
      rtmutex: Delete scriptable tester · 1b0b7c17
      由 Davidlohr Bueso 提交于 
      No one uses this anymore, and this is not the first time the
idea of replacing it with a (now possible) userspace side.
Lock stealing logic was removed long ago in when the lock
was granted to the highest prio.
Signed-off-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1435782588-4177-2-git-send-email-dave@stgolabs.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      1b0b7c17
    • D
      futex: Fault/error injection capabilities · ab51fbab
      由 Davidlohr Bueso 提交于 
      Although futexes are well known for being a royal pita,
we really have very little debugging capabilities - except
for relying on tglx's eye half the time.

By simply making use of the existing fault-injection machinery,
we can improve this situation, allowing generating artificial
uaddress faults and deadlock scenarios. Of course, when this is
disabled in production systems, the overhead for failure checks
is practically zero -- so this is very cheap at the same time.
Future work would be nice to now enhance trinity to make use of
this.

There is a special tunable 'ignore-private', which can filter
out private futexes. Given the tsk->make_it_fail filter and
this option, pi futexes can be narrowed down pretty closely.
Signed-off-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <darren@dvhart.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Link: http://lkml.kernel.org/r/1435645562-975-3-git-send-email-dave@stgolabs.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      ab51fbab
  39. 18 7月, 2015 1 次提交
  41. 04 7月, 2015 1 次提交
  43. 28 5月, 2015 3 次提交
    • P
      rcu: Conditionally compile RCU's eqs warnings · 1ce46ee5
      由 Paul E. McKenney 提交于 
      This commit applies some warning-omission micro-optimizations to RCU's
various extended-quiescent-state functions, which are on the kernel/user
hotpath for CONFIG_NO_HZ_FULL=y.
Reported-by: NRik van Riel <riel@redhat.com>
Reported by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      1ce46ee5
    • P
      rcu: Directly drive TASKS_RCU from Kconfig · 82d0f4c0
      由 Paul E. McKenney 提交于 
      Currently, Kconfig will ask the user whether TASKS_RCU should be set.
This is silly because Kconfig already has all the information that it
needs to set this parameter.  This commit therefore directly drives
the value of TASKS_RCU via "select" statements.  Which means that
as subsystems require TASKS_RCU, those subsystems will need to add
"select" statements of their own.
Reported-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: NPranith Kumar <bobby.prani@gmail.com>
      82d0f4c0
    • P
      rcu: Provide diagnostic option to slow down grace-period scans · 0f41c0dd
      由 Paul E. McKenney 提交于 
      Grace-period scans of the rcu_node combining tree normally
proceed quite quickly, so that it is very difficult to reproduce
races against them.  This commit therefore allows grace-period
pre-initialization and cleanup to be artificially slowed down,
increasing race-reproduction probability.  A pair of pairs of new
Kconfig parameters are provided, RCU_TORTURE_TEST_SLOW_PREINIT to
enable the slowing down of propagating CPU-hotplug changes up the
combining tree along with RCU_TORTURE_TEST_SLOW_PREINIT_DELAY to
specify the delay in jiffies, and RCU_TORTURE_TEST_SLOW_CLEANUP
to enable the slowing down of the end-of-grace-period cleanup scan
along with RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY to specify the delay
in jiffies.  Boot-time parameters named rcutree.gp_preinit_delay and
rcutree.gp_cleanup_delay allow these delays to be specified at boot time.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      0f41c0dd
  45. 15 4月, 2015 3 次提交
    • P
      rcu: Control grace-period delays directly from value · 8d7dc928
      由 Paul E. McKenney 提交于 
      In a misguided attempt to avoid an #ifdef, the use of the
gp_init_delay module parameter was conditioned on the corresponding
RCU_TORTURE_TEST_SLOW_INIT Kconfig variable, using IS_ENABLED() at
the point of use in the code.  This meant that the compiler always saw
the delay, which meant that RCU_TORTURE_TEST_SLOW_INIT_DELAY had to be
unconditionally defined.  This in turn caused "make oldconfig" to ask
pointless questions about the value of RCU_TORTURE_TEST_SLOW_INIT_DELAY
in cases where it was not even used.

This commit avoids these pointless questions by defining gp_init_delay
under #ifdef.  In one branch, gp_init_delay is initialized to
RCU_TORTURE_TEST_SLOW_INIT_DELAY and is also a module parameter (thus
allowing boot-time modification), and in the other branch gp_init_delay
is a const variable initialized by default to zero.

This approach also simplifies the code at the delay point by eliminating
the IS_DEFINED().  Because gp_init_delay is constant zero in the no-delay
case intended for production use, the "gp_init_delay > 0" check causes
the delay to become dead code, as desired in this case.  In addition,
this commit replaces magic constant "10" with the preprocessor variable
PER_RCU_NODE_PERIOD, which controls the number of grace periods that
are allowed to elapse at full speed before a delay is inserted.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      8d7dc928
    • V
      Kconfig: memtest: update number of test patterns up to 17 · 8d8cfb47
      由 Vladimir Murzin 提交于 
      Additional test patterns for memtest were introduced since commit
63823126 ("x86: memtest: add additional (regular) test patterns"),
but looks like Kconfig was not updated that time.

Update Kconfig entry with the actual number of maximum test patterns.
Signed-off-by: NVladimir Murzin <vladimir.murzin@arm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8d8cfb47
    • V
      mm: move memtest under mm · 4a20799d
      由 Vladimir Murzin 提交于 
      Memtest is a simple feature which fills the memory with a given set of
patterns and validates memory contents, if bad memory regions is detected
it reserves them via memblock API.  Since memblock API is widely used by
other architectures this feature can be enabled outside of x86 world.

This patch set promotes memtest to live under generic mm umbrella and
enables memtest feature for arm/arm64.

It was reported that this patch set was useful for tracking down an issue
with some errant DMA on an arm64 platform.

This patch (of 6):

There is nothing platform dependent in the core memtest code, so other
platforms might benefit from this feature too.

[linux@roeck-us.net: MEMTEST depends on MEMBLOCK]
Signed-off-by: NVladimir Murzin <vladimir.murzin@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NMark Rutland <mark.rutland@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4a20799d
  47. 13 3月, 2015 2 次提交
    • J
      timekeeping: Add debugging checks to warn if we see delays · 3c17ad19
      由 John Stultz 提交于 
      Recently there's been requests for better sanity
checking in the time code, so that it's more clear
when something is going wrong, since timekeeping issues
could manifest in a large number of strange ways in
various subsystems.

Thus, this patch adds some extra infrastructure to
add a check to update_wall_time() to print two new
warnings:

 1) if we see the call delayed beyond the 'max_cycles'
    overflow point,

 2) or if we see the call delayed beyond the clocksource's
    'max_idle_ns' value, which is currently 50% of the
    overflow point.

This extra infrastructure is conditional on
a new CONFIG_DEBUG_TIMEKEEPING option, also
added in this patch - default off.

Tested this a bit by halting qemu for specified
lengths of time to trigger the warnings.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-5-git-send-email-john.stultz@linaro.org
[ Improved the changelog and the messages a bit. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      3c17ad19
    • P
      rcutorture: Default to grace-period-initialization delays · 186bea5d
      由 Paul E. McKenney 提交于 
      Given that CPU-hotplug events are now applied only at the starts of
grace periods, it makes sense to unconditionally enable slow grace-period
initialization for rcutorture testing.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      186bea5d
  49. 12 3月, 2015 1 次提交
    • P
      rcu: Provide diagnostic option to slow down grace-period initialization · 37745d28
      由 Paul E. McKenney 提交于 
      Grace-period initialization normally proceeds quite quickly, so
that it is very difficult to reproduce races against grace-period
initialization.  This commit therefore allows grace-period
initialization to be artificially slowed down, increasing
race-reproduction probability.  A pair of new Kconfig parameters are
provided, CONFIG_RCU_TORTURE_TEST_SLOW_INIT to enable the slowdowns, and
CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY to specify the number of jiffies
of slowdown to apply.  A boot-time parameter named rcutree.gp_init_delay
allows boot-time delay to be specified.  By default, no delay will be
applied even if CONFIG_RCU_TORTURE_TEST_SLOW_INIT is set.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      37745d28
  51. 27 2月, 2015 1 次提交
  53. 18 2月, 2015 1 次提交
    • J
      scripts/gdb: add infrastructure · 3ee7b3fa
      由 Jan Kiszka 提交于 
      This provides the basic infrastructure to load kernel-specific python
helper scripts when debugging the kernel in gdb.

The loading mechanism is based on gdb loading for <objfile>-gdb.py when
opening <objfile>.  Therefore, this places a corresponding link to the
main helper script into the output directory that contains vmlinux.

The main scripts will pull in submodules containing Linux specific gdb
commands and functions.  To avoid polluting the source directory with
compiled python modules, we link to them from the object directory.

Due to gdb.parse_and_eval and string redirection for gdb.execute, we
depend on gdb >= 7.2.

This feature is enabled via CONFIG_GDB_SCRIPTS.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Acked-by: Michal Marek <mmarek@suse.cz>		[kbuild stuff]
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3ee7b3fa
  55. 14 2月, 2015 1 次提交
    • A
      kasan: add kernel address sanitizer infrastructure · 0b24becc
      由 Andrey Ryabinin 提交于 
      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: NAndrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: NMichal Marek <mmarek@suse.cz>
Signed-off-by: NAndrey 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0b24becc
  57. 13 2月, 2015 1 次提交
  59. 31 1月, 2015 1 次提交