- 16 Oct, 2013 1 commit
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Peter Zijlstra authored
There's been reports of high NMI handler overhead, highlighted by such kernel messages: [ 3697.380195] perf samples too long (10009 > 10000), lowering kernel.perf_event_max_sample_rate to 13000 [ 3697.389509] INFO: NMI handler (perf_event_nmi_handler) took too long to run: 9.331 msecs Don Zickus analyzed the source of the overhead and reported: > While there are a few places that are causing latencies, for now I focused on > the longest one first. It seems to be 'copy_user_from_nmi' > > intel_pmu_handle_irq -> > intel_pmu_drain_pebs_nhm -> > __intel_pmu_drain_pebs_nhm -> > __intel_pmu_pebs_event -> > intel_pmu_pebs_fixup_ip -> > copy_from_user_nmi > > In intel_pmu_pebs_fixup_ip(), if the while-loop goes over 50, the sum of > all the copy_from_user_nmi latencies seems to go over 1,000,000 cycles > (there are some cases where only 10 iterations are needed to go that high > too, but in generall over 50 or so). At this point copy_user_from_nmi > seems to account for over 90% of the nmi latency. The solution to that is to avoid having to call copy_from_user_nmi() for every instruction. Since we already limit the max basic block size, we can easily pre-allocate a piece of memory to copy the entire thing into in one go. Don reported this test result: > Your patch made a huge difference in improvement. The > copy_from_user_nmi() no longer hits the million of cycles. I still > have a batch of 100,000-300,000 cycles. My longest NMI paths used > to be dominated by copy_from_user_nmi, now it is not (I have to dig > up the new hot path). Reported-and-tested-by:
Don Zickus <dzickus@redhat.com> Cc: jmario@redhat.com Cc: acme@infradead.org Cc: dave.hansen@linux.intel.com Cc: eranian@google.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20131016105755.GX10651@twins.programming.kicks-ass.netSigned-off-by:
Ingo Molnar <mingo@kernel.org>
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- 15 Oct, 2013 2 commits
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Ingo Molnar authored
Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo: * kcore annotation improvements, including build-id cache support, multi map 'call' instruction navigation fixes, kcore address validation, objdump workarounds. From Adrian Hunter. * 'trace' beautifiers for lots of syscall arguments, from Arnaldo Carvalho de Melo. * More compact 'trace' output by suppressing zeroed args, from Arnaldo Carvalho de Melo. * Show thread COMM by default in 'trace', from Arnaldo Carvalho de Melo. * Show path associated with fd in live sessions, using a 'vfs_getname' 'perf probe' created dynamic tracepoint or by looking at /proc/pid/fd, from Arnaldo Carvalho de Melo. * Memory and mmap leak fixes from Chenggang Qin. * Add option to show full timestamp in 'trace', from David Ahern. * Add 'record' command in 'trace', to record raw_syscalls:*, from David Ahern. * Add summary option to dump syscall statistics in 'trace', from David Ahern. * Fix comm resolution in 'trace' when reading events from file, from David Ahern. * Improved messages when doing profiling in all or a subset of CPUs using a workload as the session delimitator, as in: 'perf stat --cpu 0,2 sleep 10s' from Arnaldo Carvalho de Melo. * Add units to nanosec-based counters in 'perf stat', from David Ahern. * Assorted build fixes for from David Ahern and Jiri Olsa. * 'perf lock' fixes and cleanups, from Davidlohr Bueso. * Memory leak fixes in 'perf test', from Felipe Pena. * Build system super speedups, from Ingo Molnar. * Fix mmap_read event overflow, from Jiri Olsa. * Code cleanups from Jiri Olsa. * Allow specifying B/K/M/G unit to the --mmap-pages arguments, from Jiri Olsa. * Separate the GTK support in a separate libperf-gtk.so DSO, that is only loaded when --gtk is specified, from Namhyung Kim. * Fixes for some memory leaks, from Namhyumg Kim. * Fix srcline sort key behavior, from Namhyung Kim. * Fix failing assertions in numa bench, from Petr Holasek. * perf bash completion fixes and improvements from Ramkumar Ramachandra. * Improve error messages in 'trace', providing hints about system configuration steps needed for using it, from Ramkumar Ramachandra. * Remove bogus info when using 'perf stat' -e cycles/instructions, from Ramkumar Ramachandra. * Support for Openembedded/Yocto -dbg packages, from Ricardo Ribalda Delgado. * Implement addr2line directly using libbfd, from Roberto Vitillo. * Add new option --ignore-vmlinux for perf top, from Willy Tarreau. Signed-off-by:
Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by:
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Ingo Molnar authored
Merge Linux v3.12-rc5, to pick up the latest fixes. Signed-off-by:
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- 14 Oct, 2013 24 commits
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Chenggang Qin authored
In function filename__read_debuglink(), while the ELF file is opend and mmapped in elf_begin(), but if this file is considered to not be usable during the following code, we will goto the close(fd) directly. The elf_end() is skipped. So, the mmaped ELF file cannot be munmapped. The mmapped areas exist during the life of perf. This is a memory leak. This patch fixed this bug. Reviewed-by:
Namhyung Kim <namhyung@kernel.org> Signed-off-by:
Chenggang Qin <chenggang.qcg@taobao.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Chenggang Qin <chenggang.qcg@taobao.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Yanmin Zhang <yanmin.zhang@intel.com> Link: http://lkml.kernel.org/r/1381451279-4109-1-git-send-email-chenggang.qin@gmail.comSigned-off-by:
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Chenggang Qin authored
In function symbols__fixup_duplicate(), while duplicated symbols are found, only the rb_node is removed from the tree. The symbol structures themself are ignored. Then, these memory areas are lost. Signed-off-by:
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Adrian Hunter authored
The target address is provided by objdump and is not necessary a memory address. Add a helper to get the correct address. Signed-off-by:
Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/r/1381747424-3557-8-git-send-email-adrian.hunter@intel.comSigned-off-by:
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Adrian Hunter authored
kcore can be used to view the running kernel object code. However, kcore changes as modules are loaded and unloaded, and when the kernel decides to modify its own code. Consequently it is useful to create a copy of kcore at a particular time. Unlike vmlinux, kcore is not unique for a given build-id. And in addition, the kallsyms and modules files are also needed. The tool therefore creates a directory: ~/.debug/[kernel.kcore]/<build-id>/<YYYYmmddHHMMSShh> which contains: kcore, kallsyms and modules. Note that the copied kcore contains only code sections. See the kcore_copy() function for how that is determined. The tool will not make additional copies of kcore if there is already one with the same modules at the same addresses. Currently, perf tools will not look for kcore in the cache. That is addressed in another patch. Signed-off-by:
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Adrian Hunter authored
When following a call, annotate_browser__callq() uses the current symbol's map to look up the target ip. That will not work if the target ip is on a map with a different mapping (i.e. start - pgoff is different). Signed-off-by:
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Adrian Hunter authored
When no vmlinux is found, tools will use kallsyms and, if possible, kcore. Add the ability to find kcore in the build-id cache. Signed-off-by:
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Adrian Hunter authored
Add a function to copy a file specifying the permissions to use for the created file. Signed-off-by:
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Adrian Hunter authored
Use the new map_groups__find_ams() method to find kcore symbols on other maps. Signed-off-by:
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Ingo Molnar authored
Namhyung Kim noticed that the autodep .d file inclusion rule was unnecessarily complicated: > > +-include *.d */*.d > > Hmm.. this */*.d part is really needed? Only include *.d files. Reported-by:
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Ingo Molnar authored
Namhyung Kim noticed that the stackprotector testcase was incomplete: > The flag being checked should be -"W"stack-protector instead of > -"f"stack-protector. And the gcc manpage says that -Wstack-protector is > only active when -fstack-protector is active. So the end result should > look like > > $(BUILD) -Werror -fstack-protector -Wstack-protector Add -Wstack-protector. Reported-by:
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Ingo Molnar authored
Namhyung Kim noticed that the volatile-register-var feature check is superfluous: > The gcc manpage says this warning is enabled by -Wall, and we add -Wall > to CFLAGS before doing feature checks. So all gcc versions that support > -Wvolatile-register-var enables it by default without this check and > older gcc versions will always fail the feature check. Remove it - this will further speed up feature checks. Reported-by:
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Ingo Molnar authored
Ulrich Drepper and Namhyung Kim reported that the libelf logic in config/Makefile is duplicated in part. Remove the duplication, and also remove the now unused FLAGS_LIBELF variable. Reported-by:
Ulrich Drepper <drepper@gmail.com> Reported-by:
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Ingo Molnar authored
Namhyung Kim reported these duplicate DPACKAGE definitions: test-libbfd: $(BUILD) -DPACKAGE='perf' -DPACKAGE=perf -lbfd -ldl Fix all affected places and use Namhyung's suggestion that the definition should look like a normal C string: -DPACKAGE='"perf"'. Reported-by: -
Ingo Molnar authored
Arnaldo reported that 'make DEBUG=1' does not work anymore. The reason is that 'Makefile' only passes it through to 'Makefile.perf' via the environment, but 'Makefile.perf' checks that it's a command line option: ifeq ("$(origin DEBUG)", "command line") PERF_DEBUG = $(DEBUG) endif So pass it through properly, and also clean up DEBUG parameter handling while at it and fix a couple of annoyances: - DEBUG=0 used to be interpreted as 'debugging on'. Turn it into 'debugging off' instead. - Same was the case for 'DEBUG=' - turn that into debug-off as well. - Pass in just a clean, sanitized 'DEBUG' value and get rid of the intermediate, unnecessary PERF_DEBUG variable. Reported-by: -
Ingo Molnar authored
Arnaldo reported that non-existent build directories were not recognized properly. The reason is readlink failure causing 'O' to become empty. Solve it by passing through the 'O' variable unmodified if readlink fails. Reported-by:
Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20131009150023.GA10167@gmail.comSigned-off-by:
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Arnaldo Carvalho de Melo authored
Add a function to find a symbol using an ip that might be on a different map. Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/r/1381747424-3557-2-git-send-email-adrian.hunter@intel.comSigned-off-by:
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Adrian Hunter authored
The objdump tool fails to annotate module symbols when looking at kcore. Workaround this by extracting object code from kcore and putting it in a temporary file for objdump to use instead. The temporary file is created to look like kcore but contains only the function being disassembled. Signed-off-by:
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Adrian Hunter authored
Before using kcore we need to check that modules are in memory at the same addresses that they were when data was recorded. This is done because, while we could remap symbols to different addresses, the object code linkages would still be different which would provide an erroneous view of the object code. Signed-off-by:
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Jiri Olsa authored
We fail build with NO_DEMANGLE with missing -lbfd externals error. The reason is that we now use bfd code in srcline object: perf tools: Implement addr2line directly using libbfd So we need to check/add -lbfd always now. Signed-off-by:Jiri Olsa <jolsa@redhat.com> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
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Felipe Pena authored
Fix for a memory leak on test_file() function in dso-data.c. Signed-off-by:
Felipe Pena <felipensp@gmail.com> Acked-by:
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David Ahern authored
trace-event-parse.c:parse_proc_kallsyms() Old GCC (4.4.2) does not see through the code flow of get_srcline() and gets confused about the status of 'file' and 'line': CC /tmp/build/perf/util/srcline.o cc1: warnings being treated as errors util/srcline.c: In function ¿get_srcline¿: util/srcline.c:226: error: ¿file¿ may be used uninitialized in this function util/srcline.c:227: error: ¿line¿ may be used uninitialized in this function make[1]: *** [/tmp/build/perf/util/srcline.o] Error 1 make: *** [install] Error 2 make: Leaving directory `/home/acme/git/linux/tools/perf' [acme@fedora12 linux]$ Help out GCC by initializing 'file' and 'line'. Signed-off-by:David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Link: http://lkml.kernel.org/n/tip-h8k7h49z3cndqgjdftkmm9f8@git.kernel.orgSigned-off-by:
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David Ahern authored
When enabled dumps a summary of all syscalls by task with the usual statistics -- min, max, average and relative stddev. For example, make - 26341 : 3344 [ 17.4% ] 0.000 ms read : 52 0.000 4.802 0.644 30.08 write : 20 0.004 0.036 0.010 21.72 open : 24 0.003 0.046 0.014 23.68 close : 64 0.002 0.055 0.008 22.53 stat : 2714 0.002 0.222 0.004 4.47 fstat : 18 0.001 0.041 0.006 46.26 mmap : 30 0.003 0.009 0.006 5.71 mprotect : 8 0.006 0.039 0.016 32.16 munmap : 12 0.007 0.077 0.020 38.25 brk : 48 0.002 0.014 0.004 10.18 rt_sigaction : 18 0.002 0.002 0.002 2.11 rt_sigprocmask : 60 0.002 0.128 0.010 32.88 access : 2 0.006 0.006 0.006 0.00 pipe : 12 0.004 0.048 0.013 35.98 vfork : 34 0.448 0.980 0.692 3.04 execve : 20 0.000 0.387 0.046 56.66 wait4 : 34 0.017 9923.287 593.221 68.45 fcntl : 8 0.001 0.041 0.013 48.79 getdents : 48 0.002 0.079 0.013 19.62 getcwd : 2 0.005 0.005 0.005 0.00 chdir : 2 0.070 0.070 0.070 0.00 getrlimit : 2 0.045 0.045 0.045 0.00 arch_prctl : 2 0.002 0.002 0.002 0.00 setrlimit : 2 0.002 0.002 0.002 0.00 openat : 94 0.003 0.005 0.003 2.11 Signed-off-by: -
David Ahern authored
Similar to other findnew based methods if the requested object is not found, add it to the list. v2: followed format of other findnew methods per acme's request Signed-off-by:
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Ramkumar Ramachandra authored
Currently, execution of 'perf trace' reports the following cryptic message to the user: $ perf trace Couldn't read the raw_syscalls tracepoints information! Typically this happens because the user does not have permissions to read the debugfs filesystem. Also handle the case when the kernel was not compiled with debugfs support or when it isn't mounted. Now, the tool prints detailed error messages: $ perf trace Error: Unable to find debugfs Hint: Was your kernel was compiled with debugfs support? Hint: Is the debugfs filesystem mounted? Hint: Try 'sudo mount -t debugfs nodev /sys/kernel/debug' $ perf trace Error: No permissions to read /sys/kernel/debug//tracing/events/raw_syscalls Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/' Signed-off-by:
Ramkumar Ramachandra <artagnon@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1380863851-14460-1-git-send-email-artagnon@gmail.com [ Added ready to use commands to fix the issues as extra hints, use the current debugfs mount point when reporting permission error, use strerror_r instead of the deprecated sys_errlist, as reported by David Ahern ] Signed-off-by:
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- 13 Oct, 2013 13 commits
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Linus Torvalds authored
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git://www.linux-watchdog.org/linux-watchdogLinus Torvalds authored
Pull watchdog fixes from Wim Van Sebroeck: "This will fix a deadlock on the ts72xx_wdt driver, fix bitmasks in the kempld_wdt driver and fix a section mismatch in the sunxi_wdt driver" * git://www.linux-watchdog.org/linux-watchdog: watchdog: sunxi: Fix section mismatch watchdog: kempld_wdt: Fix bit mask definition watchdog: ts72xx_wdt: locking bug in ioctl
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Maxime Ripard authored
This driver has a section mismatch, for probe and remove functions, leading to the following warning during the compilation. WARNING: drivers/watchdog/built-in.o(.data+0x24): Section mismatch in reference from the variable sunxi_wdt_driver to the function .init.text:sunxi_wdt_probe() The variable sunxi_wdt_driver references the function __init sunxi_wdt_probe() Signed-off-by:
Maxime Ripard <maxime.ripard@free-electrons.com> Reviewed-by:
Guenter Roeck <linux@roeck-us.net> Signed-off-by:
Wim Van Sebroeck <wim@iguana.be>
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Jingoo Han authored
STAGE_CFG bits are defined as [5:4] bits. However, '(((x) & 0x30) << 4)' handles [9:8] bits. Thus, it should be fixed in order to handle [5:4] bits. Signed-off-by:
Jingoo Han <jg1.han@samsung.com> Reviewed-by:
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Dan Carpenter authored
Calling the WDIOC_GETSTATUS & WDIOC_GETBOOTSTATUS and twice will cause a interruptible deadlock. Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by:
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git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-socLinus Torvalds authored
Pull ARM SoC fixes from Olof Johansson: "A small batch of fixes this week, mostly OMAP related. Nothing stands out as particularly controversial. Also a fix for a 3.12-rc1 timer regression for Exynos platforms, including the Chromebooks" * tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: ARM: exynos: dts: Update 5250 arch timer node with clock frequency ARM: OMAP2: RX-51: Add missing max_current to rx51_lp5523_led_config ARM: mach-omap2: board-generic: fix undefined symbol ARM: dts: Fix pinctrl mask for omap3 ARM: OMAP3: Fix hardware detection for omap3630 when booted with device tree ARM: OMAP2: gpmc-onenand: fix sync mode setup with DT
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Yuvaraj Kumar C D authored
Without the "clock-frequency" property in arch timer node, could able to see the below crash dump. [<c0014e28>] (unwind_backtrace+0x0/0xf4) from [<c0011808>] (show_stack+0x10/0x14) [<c0011808>] (show_stack+0x10/0x14) from [<c036ac1c>] (dump_stack+0x7c/0xb0) [<c036ac1c>] (dump_stack+0x7c/0xb0) from [<c01ab760>] (Ldiv0_64+0x8/0x18) [<c01ab760>] (Ldiv0_64+0x8/0x18) from [<c0062f60>] (clockevents_config.part.2+0x1c/0x74) [<c0062f60>] (clockevents_config.part.2+0x1c/0x74) from [<c0062fd8>] (clockevents_config_and_register+0x20/0x2c) [<c0062fd8>] (clockevents_config_and_register+0x20/0x2c) from [<c02b8e8c>] (arch_timer_setup+0xa8/0x134) [<c02b8e8c>] (arch_timer_setup+0xa8/0x134) from [<c04b47b4>] (arch_timer_init+0x1f4/0x24c) [<c04b47b4>] (arch_timer_init+0x1f4/0x24c) from [<c04b40d8>] (clocksource_of_init+0x34/0x58) [<c04b40d8>] (clocksource_of_init+0x34/0x58) from [<c049ed8c>] (time_init+0x20/0x2c) [<c049ed8c>] (time_init+0x20/0x2c) from [<c049b95c>] (start_kernel+0x1e0/0x39c) THis is because the Exynos u-boot, for example on the Chromebooks, doesn't set up the CNTFRQ register as expected by arch_timer. Instead, we have to specify the frequency in the device tree like this. Signed-off-by:
Yuvaraj Kumar C D <yuvaraj.cd@samsung.com> [olof: Changed subject, added comment, elaborated on commit message] Signed-off-by:
Olof Johansson <olof@lixom.net>
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Olof Johansson authored
Merge tag 'fixes-against-v3.12-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes From Tony Lindgren: Few fixes for omap3 related hangs and errors that people have noticed now that people are actually using the device tree based booting for omap3. Also one regression fix for timer compile for dra7xx when omap5 is not selected, and a LED regression fix for n900. * tag 'fixes-against-v3.12-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap: ARM: OMAP2: RX-51: Add missing max_current to rx51_lp5523_led_config ARM: mach-omap2: board-generic: fix undefined symbol ARM: dts: Fix pinctrl mask for omap3 ARM: OMAP3: Fix hardware detection for omap3630 when booted with device tree ARM: OMAP2: gpmc-onenand: fix sync mode setup with DT Signed-off-by:
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git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linuxLinus Torvalds authored
Pull parisc fixes from Helge Deller: "This patchset includes a bugfix to prevent a kernel crash when memory in page zero is accessed by the kernel itself, e.g. via probe_kernel_read(). Furthermore we now export flush_cache_page() which is needed (indirectly) by the lustre filesystem. The other patches remove unused functions and optimizes the page fault handler to only evaluate variables if needed, which again protects against possible kernel crashes" * 'parisc-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: let probe_kernel_read() capture access to page zero parisc: optimize variable initialization in do_page_fault parisc: fix interruption handler to respect pagefault_disable() parisc: mark parisc_terminate() noreturn and cold. parisc: remove unused syscall_ipi() function. parisc: kill SMP single function call interrupt parisc: Export flush_cache_page() (needed by lustre)
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git://git.infradead.org/users/vkoul/slave-dmaLinus Torvalds authored
Pull slave-dmaengine fixes from Vinod Koul: "Another week, time to send another fixes request taking time out of extended weekend for the festivities in this part of the world. We have two fixes from Sergei for rcar driver and one fixing memory leak of edma driver by Geyslan" * 'fixes' of git://git.infradead.org/users/vkoul/slave-dma: dma: edma.c: remove edma_desc leakage rcar-hpbdma: add parameter to set_slave() method rcar-hpbdma: remove shdma_free_irq() calls
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Helge Deller authored
Signed-off-by:Helge Deller <deller@gmx.de>
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John David Anglin authored
The attached change defers the initialization of the variables tsk, mm and flags until they are needed. As a result, the code won't crash if a kernel probe is done with a corrupt context and the code will be better optimized. Signed-off-by:
John David Anglin <dave.anglin@bell.net> Signed-off-by:
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Helge Deller authored
Running an "echo t > /proc/sysrq-trigger" crashes the parisc kernel. The problem is, that in print_worker_info() we try to read the workqueue info via the probe_kernel_read() functions which use pagefault_disable() to avoid crashes like this: probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); probe_kernel_read(name, wq->name, sizeof(name) - 1); The problem here is, that the first probe_kernel_read(&pwq) might return zero in pwq and as such the following probe_kernel_reads() try to access contents of the page zero which is read protected and generate a kernel segfault. With this patch we fix the interruption handler to call parisc_terminate() directly only if pagefault_disable() was not called (in which case preempt_count()==0). Otherwise we hand over to the pagefault handler which will try to look up the faulting address in the fixup tables. Signed-off-by:
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