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2016-09-22lib: spinlock: Change MSM_WATCHDOG_V2 to QCOM_WATCHDOG_V2Kyle Yan
Change DEBUG_SPINLOCK_BITE_ON_BUG to depend on QCOM_WATCHDOG_V2 instead of MSM_WATCHDOG_V2 as MSM_WATCHDOG_V2 is no longer used. CRs-Fixed: 1070295 Change-Id: I549abf9978a19da5bbd258d803287464cd73f23c Signed-off-by: Kyle Yan <kyan@codeaurora.org>
2016-05-05workqueue: implement lockup detectorTejun Heo
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. CRs-Fixed: 1007459 Change-Id: Id7dfbbd2701128a942b1bcac2299e07a66db8657 Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Don 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> Git-commit: 82607adcf9cdf40fb7b5331269780c8f70ec6e35 Git-repo: git://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git Signed-off-by: Trilok Soni <tsoni@codeaurora.org>
2016-05-05lib: memtest: Add MEMTEST_ENABLE_DEFAULT optionTrilok Soni
As of now memtest remains disabled until we specify the patterns through the kernel command line. Some platforms have two different configurations files (one for debug and another for product) which can use the configuration option to enable the memtest by default (in the debug configuration file). CRs-Fixed: 1007344 Change-Id: I0bf7b33c3584f3d6cf5ef58dfe72be46212041da Signed-off-by: Trilok Soni <tsoni@codeaurora.org>
2016-05-03mm/page_owner: ask users about default setting of PAGE_OWNERTrilok Soni
Since this commit 48c96a3685795 ("mm/page_owner: keep track of page owners") doesn't enable the page_owner by default even though CONFIG_PAGE_OWNER is enabled. Add configuration option CONFIG_PAGE_OWNER_ENABLE_DEFAULT to allow user to enable it by default through the defconfig file. CRs-Fixed: 1006743 Change-Id: I9b565a34e2068bf575974eaf3dc9f7820bdd7a96 Signed-off-by: Trilok Soni <tsoni@codeaurora.org>
2016-04-22Revert "kernel: lib: allow larger stack frame size for KASan"Satya Durga Srinivasu Prabhala
This reverts commit 8bb334401c84 ("kernel: lib: allow larger stack frame size for KASan"). Stack frame size set to 5600 to fix compilation error/s if KASAN enabled by the commit 8bb334401c84 ("kernel: lib: allow larger stack frame size for KASan") in 3.18 Kernel and same commit got pulled into Kernel 4.4, which replaced stack frame size 0 with 5600 as part of resolution of merge conflict. But, by setting stack frame size to 0 will ignore stack frame size warnings and so the compilation errors. So, revert commit to fix below error while compiling Kernel 4.4 with KASAN enabled and GCC 5.1 compiler. kernel/net/wireless/nl80211.c: In function 'nl80211_send_wiphy': kernel/net/wireless/nl80211.c:1745:1: warning: the frame size of \ 5760 bytes is larger than 5600 bytes [-Wframe-larger-than=] error, forbidden warning: nl80211.c:1745 make[4]: *** [net/wireless/nl80211.o] Error 1 CRs-Fixed: 1004225 Change-Id: I97e52302197c9933bec5cac3ebdc4ec73fee0816 Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
2016-03-23kmemleak : Make module scanning optional using configVignesh Radhakrishnan
Currently kmemleak scans module memory as provided in the area list. This takes up lot of time with irq's and preemption disabled. Provide a compile time configurable config to enable this functionality. Change-Id: I5117705e7e6726acdf492e7f87c0703bc1f28da0 Signed-off-by: Vignesh Radhakrishnan <vigneshr@codeaurora.org> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org> [satyap: trivial merge conflict resolution and remove duplicate entry] Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
2016-03-23sched/debug: Add Kconfig to trigger panics on all 'BUG:' conditionsMatt Wagantall
Introduce CONFIG_PANIC_ON_SCHED_BUG to trigger panics along with all 'BUG:' prints from the scheduler core, even potentially-recoverable ones such as scheduling while atomic, sleeping from invalid context, and detection of broken arch topologies. Change-Id: I5d2f561614604357a2bc7900b047e53b3a0b7c6d Signed-off-by: Matt Wagantall <mattw@codeaurora.org> [joonwoop@codeaurora.org: fixed trivial merge conflict in lib/Kconfig.debug.] Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
2016-03-23sched/debug: Make sysrq prints of sched debug data optionalMatt Wagantall
Calls to sysrq_sched_debug_show() can yield rather verbose output which contributes to log spew and, under heavy load, may increase the chances of a watchdog bark. Make printing of this data optional with the introduction of a new Kconfig, CONFIG_SYSRQ_SCHED_DEBUG. Change-Id: I5f54d901d0dea403109f7ac33b8881d967a899ed Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
2016-03-23sched/rt: Add Kconfig option to enable panicking for RT throttlingMatt Wagantall
This may be useful for detecting and debugging RT throttling issues. Change-Id: I5807a897d11997d76421c1fcaa2918aad988c6c9 Signed-off-by: Matt Wagantall <mattw@codeaurora.org> [rameezmustafa@codeaurora.org]: Port to msm-3.18] Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org> [joonwoop@codeaurora.org: fixed conflict in lib/Kconfig.debug] Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
2016-03-22lib: Kconfig.debug: Fix the recursive dependencyRohit Vaswani
An earlier commit 52a3101ed9b61787a49f3b5c298aa9240f4006dd added a recursive dependency as part of CONFIG_DEBUG_SPINLOCK lib/Kconfig.debug:585:error: recursive dependency detected! lib/Kconfig.debug:585:symbol DEBUG_SPINLOCK_BITE_ON_BUG depends on DEBUG_SPINLOCK_PANIC_ON_BUG lib/Kconfig.debug:593:symbol DEBUG_SPINLOCK_PANIC_ON_BUG depends on DEBUG_SPINLOCK_BITE_ON_BUG Fix this by adding a choice menu. Change-Id: I0e50103397bb71dec7056db5148cba988550b860 Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
2016-03-22lib: spinlock: Trigger a watchdog bite on spin_dump for rwlockPrasad Sodagudi
Currently dump_stack is printed once a spin_bug is detected for rwlock. So provide an options to trigger a panic or watchdog bite for debugging rwlock magic corruptions and lockups. Change-Id: I20807e8eceb8b81635e58701d1f9f9bd36ab5877 [abhimany: replace msm with qcom] Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org> Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>
2016-03-22lib: spinlock: Cause a watchdog bite on spin_dumpRohit Vaswani
Currently we cause a BUG_ON once a spin_bug is detected, but that causes a whole lot of processing and the other CPUs would have proceeded to perform other actions and the state of the system is moved by the time we can analyze it. Provide an option to trigger a watchdog bite instead so that we can get the traces as close to the issue as possible. Change-Id: Ic8d692ebd02c6940a3b4e5798463744db20b0026 Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
2016-03-22kernel/lib: add additional debug capabilites for data corruptionSyed Rameez Mustafa
Data corruptions in the kernel often end up in system crashes that are easier to debug closer to the time of detection. Specifically, if we do not panic immediately after lock or list corruptions have been detected, the problem context is lost in the ensuing system mayhem. Add support for allowing system crash immediately after such corruptions are detected. The CONFIG option controls the enabling/disabling of the feature. Change-Id: I9b2eb62da506a13007acff63e85e9515145909ff Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org> [abhimany: minor merge conflict resolution] Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>
2016-03-22kernel: lib: allow larger stack frame size for KASanSe Wang (Patrick) Oh
Some functions consume more than allowed stack frame size with KASan enabled and GCC warns it as an error. To avoid compilation warning, allow larger stack frame size when KASan is enabled instead of changing each file. Below is one of the warning messages for reference. kernel/net/wireless/nl80211.c: In function 'nl80211_send_wiphy': kernel/net/wireless/nl80211.c:1705:1: warning: the frame size of 5488 bytes is larger than 2048 bytes [-Wframe-larger-than=] Change-Id: I953018f459bf048366f0ba5ff7c980edcd9bbe07 Signed-off-by: Se Wang (Patrick) Oh <sewango@codeaurora.org> [satyap: trivial merge conflict resolution] Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
2016-03-22UBSAN: run-time undefined behavior sanity checkerAndrey Ryabinin
UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Git-repo: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/ Git-commit: c6d308534aef6c99904bf5862066360ae067abc4 [tsoni@codeaurora.org: trivial merge conflict resolution] CRs-Fixed: 969533 Change-Id: I048b9936b1120e0d375b7932c59de78d8ef8f411 Signed-off-by: Trilok Soni <tsoni@codeaurora.org> [satyap@codeaurora.org: trivial merge conflict resolution] Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
2016-03-22kmemleak : Make kmemleak_stack_scan optional using configVignesh Radhakrishnan
Currently we have kmemleak_stack_scan enabled by default. This can hog the cpu with pre-emption disabled for a long time starving other tasks. Make this optional at compile time, since if required we can always write to sysfs entry and enable this option. Change-Id: Ie30447861c942337c7ff25ac269b6025a527e8eb Signed-off-by: Vignesh Radhakrishnan <vigneshr@codeaurora.org> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
2016-03-22kmemleak : Make kmemleak_stack_scan optional using configVignesh Radhakrishnan
Currently we have kmemleak_stack_scan enabled by default. This can hog the cpu with pre-emption disabled for a long time starving other tasks. Make this optional at compile time, since if required we can always write to sysfs entry and enable this option. Change-Id: Ie30447861c942337c7ff25ac269b6025a527e8eb Signed-off-by: Vignesh Radhakrishnan <vigneshr@codeaurora.org> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
2016-03-22scsi: ufs: Inject errors to verify error handlingSujit Reddy Thumma
Use fault-injection framework to simulate error conditions in the controller and verify error handling mechanisms implemented in UFS host controller driver. This is used only during development and hence guarded by CONFIG_UFS_FAULT_INJECTION debug config option. Change-Id: Ia63c276c5e56d677a92332b42b670300ad82af7a Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org> [venkatg@codeaurora.org: resolved trivial merge conflicts] Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
2016-02-16hardlockup: detect hard lockups without NMIs using secondary cpusColin Cross
Emulate NMIs on systems where they are not available by using timer interrupts on other cpus. Each cpu will use its softlockup hrtimer to check that the next cpu is processing hrtimer interrupts by verifying that a counter is increasing. This patch is useful on systems where the hardlockup detector is not available due to a lack of NMIs, for example most ARM SoCs. Without this patch any cpu stuck with interrupts disabled can cause a hardware watchdog reset with no debugging information, but with this patch the kernel can detect the lockup and panic, which can result in useful debugging info. Change-Id: Ia5faf50243e19c1755201212e04c8892d929785a Signed-off-by: Colin Cross <ccross@android.com>
2015-11-09Merge tag 'modules-next-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "Nothing exciting, minor tweaks and cleanups" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: scripts: [modpost] add new sections to white list modpost: Add flag -E for making section mismatches fatal params: don't ignore the rest of cmdline if parse_one() fails modpost: abort if a module symbol is too long
2015-11-06test_printf: test printf family at runtimeRasmus Villemoes
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: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Kees 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-23lib/Kconfig.debug: disable -Wframe-larger-than warnings with KASAN=yAndrey Ryabinin
When the kernel compiled with KASAN=y, GCC adds redzones for each variable on stack. This enlarges function's stack frame and causes: 'warning: the frame size of X bytes is larger than Y bytes' The worst case I've seen for now is following: ../net/wireless/nl80211.c: In function `nl80211_send_wiphy': ../net/wireless/nl80211.c:1731:1: warning: the frame size of 5448 bytes is larger than 2048 bytes [-Wframe-larger-than=] That kind of warning becomes useless with KASAN=y. It doesn't necessarily indicate that there is some problem in the code, thus we should turn it off. (The KASAN=y stack size in increased from 16k to 32k for this reason) Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Abylay Ospan <aospan@netup.ru> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mauro Carvalho Chehab <m.chehab@samsung.com> Cc: Kozlov Sergey <serjk@netup.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-06modpost: Add flag -E for making section mismatches fatalNicolas Boichat
The section mismatch warning can be easy to miss during the kernel build process. Allow it to be marked as fatal to be easily caught and prevent bugs from slipping in. Setting CONFIG_SECTION_MISMATCH_WARN_ONLY=y causes these warnings to be non-fatal, since there are a number of section mismatches when using allmodconfig on some architectures, and we do not want to break these builds by default. Signed-off-by: Nicolas Boichat <drinkcat@chromium.org> Change-Id: Ic346706e3297c9f0d790e3552aa94e5cff9897a6 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-09-03Merge branch 'locking-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking and atomic updates from Ingo Molnar: "Main changes in this cycle are: - Extend atomic primitives with coherent logic op primitives (atomic_{or,and,xor}()) and deprecate the old partial APIs (atomic_{set,clear}_mask()) The old ops were incoherent with incompatible signatures across architectures and with incomplete support. Now every architecture supports the primitives consistently (by Peter Zijlstra) - Generic support for 'relaxed atomics': - _acquire/release/relaxed() flavours of xchg(), cmpxchg() and {add,sub}_return() - atomic_read_acquire() - atomic_set_release() This came out of porting qwrlock code to arm64 (by Will Deacon) - Clean up the fragile static_key APIs that were causing repeat bugs, by introducing a new one: DEFINE_STATIC_KEY_TRUE(name); DEFINE_STATIC_KEY_FALSE(name); which define a key of different types with an initial true/false value. Then allow: static_branch_likely() static_branch_unlikely() to take a key of either type and emit the right instruction for the case. To be able to know the 'type' of the static key we encode it in the jump entry (by Peter Zijlstra) - Static key self-tests (by Jason Baron) - qrwlock optimizations (by Waiman Long) - small futex enhancements (by Davidlohr Bueso) - ... and misc other changes" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits) jump_label/x86: Work around asm build bug on older/backported GCCs locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations locking, include/llist: Use linux/atomic.h instead of asm/cmpxchg.h locking/qrwlock: Make use of _{acquire|release|relaxed}() atomics locking/qrwlock: Implement queue_write_unlock() using smp_store_release() locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t' locking, asm-generic: Rework atomic-long.h to avoid bulk code duplication locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic locking/static_keys: Make verify_keys() static jump label, locking/static_keys: Update docs locking/static_keys: Provide a selftest jump_label: Provide a self-test s390/uaccess, locking/static_keys: employ static_branch_likely() x86, tsc, locking/static_keys: Employ static_branch_likely() locking/static_keys: Add selftest locking/static_keys: Add a new static_key interface locking/static_keys: Rework update logic locking/static_keys: Add static_key_{en,dis}able() helpers ...
2015-08-04Merge branches 'fixes.2015.07.22a' and 'initexp.2015.08.04a' into HEADPaul E. McKenney
fixes.2015.07.22a: Miscellaneous fixes. initexp.2015.08.04a: Initialization and expedited updates. (Single branch due to conflicts.)
2015-08-03locking/static_keys: Provide a selftestIngo Molnar
The 'jump label' self-test is in reality testing static keys - rename things accordingly. Also prettify the code in various places while at it. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: benh@kernel.crashing.org Cc: bp@alien8.de Cc: davem@davemloft.net Cc: ddaney@caviumnetworks.com Cc: heiko.carstens@de.ibm.com Cc: linux-kernel@vger.kernel.org Cc: liuj97@gmail.com Cc: luto@amacapital.net Cc: michael@ellerman.id.au Cc: rabin@rab.in Cc: ralf@linux-mips.org Cc: rostedt@goodmis.org Cc: vbabka@suse.cz Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/0c091ecebd78a879ed8a71835d205a691a75ab4e.1438227999.git.jbaron@akamai.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03jump_label: Provide a self-testJason Baron
Signed-off-by: Jason Baron <jbaron@akamai.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: benh@kernel.crashing.org Cc: bp@alien8.de Cc: davem@davemloft.net Cc: ddaney@caviumnetworks.com Cc: heiko.carstens@de.ibm.com Cc: linux-kernel@vger.kernel.org Cc: liuj97@gmail.com Cc: luto@amacapital.net Cc: michael@ellerman.id.au Cc: rabin@rab.in Cc: ralf@linux-mips.org Cc: rostedt@goodmis.org Cc: shuahkh@osg.samsung.com Cc: vbabka@suse.cz Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/0c091ecebd78a879ed8a71835d205a691a75ab4e.1438227999.git.jbaron@akamai.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-22rcu: Clarify CONFIG_RCU_EQS_DEBUG help textPaul E. McKenney
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-20rtmutex: Delete scriptable testerDavidlohr Bueso
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: Davidlohr 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.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-07-20futex: Fault/error injection capabilitiesDavidlohr Bueso
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: Davidlohr 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.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-07-17rcu: Remove CONFIG_RCU_CPU_STALL_INFOPaul E. McKenney
The CONFIG_RCU_CPU_STALL_INFO has been default-y for a couple of releases with no complaints, so it is time to eliminate this Kconfig option entirely, so that the long-form RCU CPU stall warnings cannot be disabled. This commit does just that. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-04sched/stat: Simplify the sched_info accounting dependencyNaveen N. Rao
Both CONFIG_SCHEDSTATS=y and CONFIG_TASK_DELAY_ACCT=y track task sched_info, which results in ugly #if clauses. Simplify the code by introducing a synthethic CONFIG_SCHED_INFO switch, selected by both. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: a.p.zijlstra@chello.nl Cc: ricklind@us.ibm.com Link: http://lkml.kernel.org/r/8d19eef800811a94b0f91bcbeb27430a884d7433.1435255405.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-27rcu: Conditionally compile RCU's eqs warningsPaul E. McKenney
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: Rik van Riel <riel@redhat.com> Reported by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-05-27rcu: Directly drive TASKS_RCU from KconfigPaul E. McKenney
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: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
2015-05-27rcu: Provide diagnostic option to slow down grace-period scansPaul E. McKenney
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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-05-06Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU fix from Ingo Molnar: "An RCU Kconfig fix that eliminates an annoying interactive kconfig question for CONFIG_RCU_TORTURE_TEST_SLOW_INIT" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Control grace-period delays directly from value
2015-04-18Merge branch 'for-mingo' of ↵Ingo Molnar
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent Pull RCU fix from Paul E. McKenney: "This series contains a single change that fixes Kconfig asking pointless questions." Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-14rcu: Control grace-period delays directly from valuePaul E. McKenney
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>
2015-04-14Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge first patchbomb from Andrew Morton: - arch/sh updates - ocfs2 updates - kernel/watchdog feature - about half of mm/ * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (122 commits) Documentation: update arch list in the 'memtest' entry Kconfig: memtest: update number of test patterns up to 17 arm: add support for memtest arm64: add support for memtest memtest: use phys_addr_t for physical addresses mm: move memtest under mm mm, hugetlb: abort __get_user_pages if current has been oom killed mm, mempool: do not allow atomic resizing memcg: print cgroup information when system panics due to panic_on_oom mm: numa: remove migrate_ratelimited mm: fold arch_randomize_brk into ARCH_HAS_ELF_RANDOMIZE mm: split ET_DYN ASLR from mmap ASLR s390: redefine randomize_et_dyn for ELF_ET_DYN_BASE mm: expose arch_mmap_rnd when available s390: standardize mmap_rnd() usage powerpc: standardize mmap_rnd() usage mips: extract logic for mmap_rnd() arm64: standardize mmap_rnd() usage x86: standardize mmap_rnd() usage arm: factor out mmap ASLR into mmap_rnd ...
2015-04-14Kconfig: memtest: update number of test patterns up to 17Vladimir Murzin
Additional test patterns for memtest were introduced since commit 63823126c221 ("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: Vladimir 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14mm: move memtest under mmVladimir Murzin
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: Vladimir Murzin <vladimir.murzin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Tested-by: Mark 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU changes from Ingo Molnar: "The main changes in this cycle were: - changes permitting use of call_rcu() and friends very early in boot, for example, before rcu_init() is invoked. - add in-kernel API to enable and disable expediting of normal RCU grace periods. - improve RCU's handling of (hotplug-) outgoing CPUs. - NO_HZ_FULL_SYSIDLE fixes. - tiny-RCU updates to make it more tiny. - documentation updates. - miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits) cpu: Provide smpboot_thread_init() on !CONFIG_SMP kernels as well cpu: Defer smpboot kthread unparking until CPU known to scheduler rcu: Associate quiescent-state reports with grace period rcu: Yet another fix for preemption and CPU hotplug rcu: Add diagnostics to grace-period cleanup rcutorture: Default to grace-period-initialization delays rcu: Handle outgoing CPUs on exit from idle loop cpu: Make CPU-offline idle-loop transition point more precise rcu: Eliminate ->onoff_mutex from rcu_node structure rcu: Process offlining and onlining only at grace-period start rcu: Move rcu_report_unblock_qs_rnp() to common code rcu: Rework preemptible expedited bitmask handling rcu: Remove event tracing from rcu_cpu_notify(), used by offline CPUs rcutorture: Enable slow grace-period initializations rcu: Provide diagnostic option to slow down grace-period initialization rcu: Detect stalls caused by failure to propagate up rcu_node tree rcu: Eliminate empty HOTPLUG_CPU ifdef rcu: Simplify sync_rcu_preempt_exp_init() rcu: Put all orphan-callback-related code under same comment rcu: Consolidate offline-CPU callback initialization ...
2015-03-20Merge branches 'doc.2015.02.26a', 'earlycb.2015.03.03a', ↵Paul E. McKenney
'fixes.2015.03.03a', 'gpexp.2015.02.26a', 'hotplug.2015.03.20a', 'sysidle.2015.02.26b' and 'tiny.2015.02.26a' into HEAD doc.2015.02.26a: Documentation changes earlycb.2015.03.03a: Permit early-boot RCU callbacks fixes.2015.03.03a: Miscellaneous fixes gpexp.2015.02.26a: In-kernel expediting of normal grace periods hotplug.2015.03.20a: CPU hotplug fixes sysidle.2015.02.26b: NO_HZ_FULL_SYSIDLE fixes tiny.2015.02.26a: TINY_RCU fixes
2015-03-13timekeeping: Add debugging checks to warn if we see delaysJohn Stultz
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: John 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: Ingo Molnar <mingo@kernel.org>
2015-03-12rcutorture: Default to grace-period-initialization delaysPaul E. McKenney
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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-03-11rcu: Provide diagnostic option to slow down grace-period initializationPaul E. McKenney
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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-02-26rcu: Drive PROVE_RCU directly off of PROVE_LOCKINGPaul E. McKenney
In the past, it has been useful to enable PROVE_LOCKING without also enabling PROVE_RCU. However, experience with PROVE_RCU over the past few years has demonstrated its usefulness, so this commit makes PROVE_LOCKING directly imply PROVE_RCU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-02-17scripts/gdb: add infrastructureJan Kiszka
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: Jan 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13kasan: add kernel address sanitizer infrastructureAndrey Ryabinin
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>
2015-02-12hexdump: introduce test suiteAndy Shevchenko
Test different scenarios of function calls located in lib/hexdump.c. Currently hex_dump_to_buffer() is only tested and test data is provided for little endian CPUs. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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