linux/kernel/trace, branch v4.0

ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled

2015-03-09T14:55:34Z

Some archs (specifically PowerPC), are sensitive with the ordering of the enabling of the calls to function tracing and setting of the function to use to be traced. That is, update_ftrace_function() sets what function the ftrace_caller trampoline should call. Some archs require this to be set before calling ftrace_run_update_code(). Another bug was discovered, that ftrace_startup_sysctl() called ftrace_run_update_code() directly. If the function the ftrace_caller trampoline changes, then it will not be updated. Instead a call to ftrace_startup_enable() should be called because it tests to see if the callback changed since the code was disabled, and will tell the arch to update appropriately. Most archs do not need this notification, but PowerPC does. The problem could be seen by the following commands: # echo 0 > /proc/sys/kernel/ftrace_enabled # echo function > /sys/kernel/debug/tracing/current_tracer # echo 1 > /proc/sys/kernel/ftrace_enabled # cat /sys/kernel/debug/tracing/trace The trace will show that function tracing was not active. Cc: stable@vger.kernel.org # 2.6.27+ Signed-off-by: Steven Rostedt

ftrace: Fix en(dis)able graph caller when en(dis)abling record via sysctl

2015-03-09T14:50:51Z

When ftrace is enabled globally through the proc interface, we must check if ftrace_graph_active is set. If it is set, then we should also pass the FTRACE_START_FUNC_RET command to ftrace_run_update_code(). Similarly, when ftrace is disabled globally through the proc interface, we must check if ftrace_graph_active is set. If it is set, then we should also pass the FTRACE_STOP_FUNC_RET command to ftrace_run_update_code(). Consider the following situation. # echo 0 > /proc/sys/kernel/ftrace_enabled After this ftrace_enabled = 0. # echo function_graph > /sys/kernel/debug/tracing/current_tracer Since ftrace_enabled = 0, ftrace_enable_ftrace_graph_caller() is never called. # echo 1 > /proc/sys/kernel/ftrace_enabled Now ftrace_enabled will be set to true, but still ftrace_enable_ftrace_graph_caller() will not be called, which is not desired. Further if we execute the following after this: # echo nop > /sys/kernel/debug/tracing/current_tracer Now since ftrace_enabled is set it will call ftrace_disable_ftrace_graph_caller(), which causes a kernel warning on the ARM platform. On the ARM platform, when ftrace_enable_ftrace_graph_caller() is called, it checks whether the old instruction is a nop or not. If it's not a nop, then it returns an error. If it is a nop then it replaces instruction at that address with a branch to ftrace_graph_caller. ftrace_disable_ftrace_graph_caller() behaves just the opposite. Therefore, if generic ftrace code ever calls either ftrace_enable_ftrace_graph_caller() or ftrace_disable_ftrace_graph_caller() consecutively two times in a row, then it will return an error, which will cause the generic ftrace code to raise a warning. Note, x86 does not have an issue with this because the architecture specific code for ftrace_enable_ftrace_graph_caller() and ftrace_disable_ftrace_graph_caller() does not check the previous state, and calling either of these functions twice in a row has no ill effect. Link: http://lkml.kernel.org/r/e4fbe64cdac0dd0e86a3bf914b0f83c0b419f146.1425666454.git.panand@redhat.com Cc: stable@vger.kernel.org # 2.6.31+ Signed-off-by: Pratyush Anand [ removed extra if (ftrace_start_up) and defined ftrace_graph_active as 0 if CONFIG_FUNCTION_GRAPH_TRACER is not set. ] Signed-off-by: Steven Rostedt

ftrace: Clear REGS_EN and TRAMP_EN flags on disabling record via sysctl

2015-03-09T14:46:00Z

When /proc/sys/kernel/ftrace_enabled is set to zero, all function tracing is disabled. But the records that represent the functions still hold information about the ftrace_ops that are hooked to them. ftrace_ops may request "REGS" (have a full set of pt_regs passed to the callback), or "TRAMP" (the ops has its own trampoline to use). When the record is updated to represent the state of the ops hooked to it, it sets "REGS_EN" and/or "TRAMP_EN" to state that the callback points to the correct trampoline (REGS has its own trampoline). When ftrace_enabled is set to zero, all ftrace locations are a nop, so they do not point to any trampoline. But the _EN flags are still set. This can cause the accounting to go wrong when ftrace_enabled is cleared and an ops that has a trampoline is registered or unregistered. For example, the following will cause ftrace to crash: # echo function_graph > /sys/kernel/debug/tracing/current_tracer # echo 0 > /proc/sys/kernel/ftrace_enabled # echo nop > /sys/kernel/debug/tracing/current_tracer # echo 1 > /proc/sys/kernel/ftrace_enabled # echo function_graph > /sys/kernel/debug/tracing/current_tracer As function_graph uses a trampoline, when ftrace_enabled is set to zero the updates to the record are not done. When enabling function_graph again, the record will still have the TRAMP_EN flag set, and it will look for an op that has a trampoline other than the function_graph ops, and fail to find one. Cc: stable@vger.kernel.org # 3.17+ Reported-by: Pratyush Anand Signed-off-by: Steven Rostedt

tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks

2015-02-14T05:21:37Z

printk and friends can now format bitmaps using '%*pb[l]'. cpumask and nodemask also provide cpumask_pr_args() and nodemask_pr_args() respectively which can be used to generate the two printf arguments necessary to format the specified cpu/nodemask. Signed-off-by: Tejun Heo Cc: Steven Rostedt Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2015-02-12T16:37:41Z

Pull tracing updates from Steven Rostedt: "The updates included in this pull request for ftrace are: o Several clean ups to the code One such clean up was to convert to 64 bit time keeping, in the ring buffer benchmark code. o Adding of __print_array() helper macro for TRACE_EVENT() o Updating the sample/trace_events/ to add samples of different ways to make trace events. Lots of features have been added since the sample code was made, and these features are mostly unknown. Developers have been making their own hacks to do things that are already available. o Performance improvements. Most notably, I found a performance bug where a waiter that is waiting for a full page from the ring buffer will see that a full page is not available, and go to sleep. The sched event caused by it going to sleep would cause it to wake up again. It would see that there was still not a full page, and go back to sleep again, and that would wake it up again, until finally it would see a full page. This change has been marked for stable. Other improvements include removing global locks from fast paths" * tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ring-buffer: Do not wake up a splice waiter when page is not full tracing: Fix unmapping loop in tracing_mark_write tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT() tracing: Add TRACE_EVENT_FN example tracing: Add TRACE_EVENT_CONDITION sample tracing: Update the TRACE_EVENT fields available in the sample code tracing: Separate out initializing top level dir from instances tracing: Make tracing_init_dentry_tr() static trace: Use 64-bit timekeeping tracing: Add array printing helper tracing: Remove newline from trace_printk warning banner tracing: Use IS_ERR() check for return value of tracing_init_dentry() tracing: Remove unneeded includes of debugfs.h and fs.h tracing: Remove taking of trace_types_lock in pipe files tracing: Add ref count to tracer for when they are being read by pipe

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2015-02-12T01:42:32Z

Pull s390 updates from Martin Schwidefsky: - The remaining patches for the z13 machine support: kernel build option for z13, the cache synonym avoidance, SMT support, compare-and-delay for spinloops and the CES5S crypto adapater. - The ftrace support for function tracing with the gcc hotpatch option. This touches common code Makefiles, Steven is ok with the changes. - The hypfs file system gets an extension to access diagnose 0x0c data in user space for performance analysis for Linux running under z/VM. - The iucv hvc console gets wildcard spport for the user id filtering. - The cacheinfo code is converted to use the generic infrastructure. - Cleanup and bug fixes. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (42 commits) s390/process: free vx save area when releasing tasks s390/hypfs: Eliminate hypfs interval s390/hypfs: Add diagnose 0c support s390/cacheinfo: don't use smp_processor_id() in preemptible context s390/zcrypt: fixed domain scanning problem (again) s390/smp: increase maximum value of NR_CPUS to 512 s390/jump label: use different nop instruction s390/jump label: add sanity checks s390/mm: correct missing space when reporting user process faults s390/dasd: cleanup profiling s390/dasd: add locking for global_profile access s390/ftrace: hotpatch support for function tracing ftrace: let notrace function attribute disable hotpatching if necessary ftrace: allow architectures to specify ftrace compile options s390: reintroduce diag 44 calls for cpu_relax() s390/zcrypt: Add support for new crypto express (CEX5S) adapter. s390/zcrypt: Number of supported ap domains is not retrievable. s390/spinlock: add compare-and-delay to lock wait loops s390/tape: remove redundant if statement s390/hvc_iucv: add simple wildcard matches to the iucv allow filter ...

ring-buffer: Do not wake up a splice waiter when page is not full

2015-02-11T12:41:42Z

When an application connects to the ring buffer via splice, it can only read full pages. Splice does not work with partial pages. If there is not enough data to fill a page, the splice command will either block or return -EAGAIN (if set to nonblock). Code was added where if the page is not full, to just sleep again. The problem is, it will get woken up again on the next event. That is, when something is written into the ring buffer, if there is a waiter it will wake it up. The waiter would then check the buffer, see that it still does not have enough data to fill a page and go back to sleep. To make matters worse, when the waiter goes back to sleep, it could cause another event, which would wake it back up again to see it doesn't have enough data and sleep again. This produces a tremendous overhead and fills the ring buffer with noise. For example, recording sched_switch on an idle system for 10 seconds produces 25,350,475 events!!! Create another wait queue for those waiters wanting full pages. When an event is written, it only wakes up waiters if there's a full page of data. It does not wake up the waiter if the page is not yet full. After this change, recording sched_switch on an idle system for 10 seconds produces only 800 events. Getting rid of 25,349,675 useless events (99.9969% of events!!), is something to take seriously. Cc: stable@vger.kernel.org # 3.16+ Cc: Rabin Vincent Fixes: e30f53aad220 "tracing: Do not busy wait in buffer splice" Signed-off-by: Steven Rostedt

Merge tag 'pm+acpi-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2015-02-10T23:09:41Z

Pull ACPI and power management updates from Rafael Wysocki: "We have a few new features this time, including a new SFI-based cpufreq driver, a new devfreq driver for Tegra Activity Monitor, a new devfreq class for providing its governors with raw utilization data and a new ACPI driver for AMD SoCs. Still, the majority of changes here are reworks of existing code to make it more straightforward or to prepare it for implementing new features on top of it. The primary example is the rework of ACPI resources handling from Jiang Liu, Thomas Gleixner and Lv Zheng with support for IOAPIC hotplug implemented on top of it, but there is quite a number of changes of this kind in the cpufreq core, ACPICA, ACPI EC driver, ACPI processor driver and the generic power domains core code too. The most active developer is Viresh Kumar with his cpufreq changes. Specifics: - Rework of the core ACPI resources parsing code to fix issues in it and make using resource offsets more convenient and consolidation of some resource-handing code in a couple of places that have grown analagous data structures and code to cover the the same gap in the core (Jiang Liu, Thomas Gleixner, Lv Zheng). - ACPI-based IOAPIC hotplug support on top of the resources handling rework (Jiang Liu, Yinghai Lu). - ACPICA update to upstream release 20150204 including an interrupt handling rework that allows drivers to install raw handlers for ACPI GPEs which then become entirely responsible for the given GPE and the ACPICA core code won't touch it (Lv Zheng, David E Box, Octavian Purdila). - ACPI EC driver rework to fix several concurrency issues and other problems related to events handling on top of the ACPICA's new support for raw GPE handlers (Lv Zheng). - New ACPI driver for AMD SoCs analogous to the LPSS (Low-Power Subsystem) driver for Intel chips (Ken Xue). - Two minor fixes of the ACPI LPSS driver (Heikki Krogerus, Jarkko Nikula). - Two new blacklist entries for machines (Samsung 730U3E/740U3E and 510R) where the native backlight interface doesn't work correctly while the ACPI one does (Hans de Goede). - Rework of the ACPI processor driver's handling of idle states to make the code more straightforward and less bloated overall (Rafael J Wysocki). - Assorted minor fixes related to ACPI and SFI (Andreas Ruprecht, Andy Shevchenko, Hanjun Guo, Jan Beulich, Rafael J Wysocki, Yaowei Bai). - PCI core power management modification to avoid resuming (some) runtime-suspended devices during system suspend if they are in the right states already (Rafael J Wysocki). - New SFI-based cpufreq driver for Intel platforms using SFI (Srinidhi Kasagar). - cpufreq core fixes, cleanups and simplifications (Viresh Kumar, Doug Anderson, Wolfram Sang). - SkyLake CPU support and other updates for the intel_pstate driver (Kristen Carlson Accardi, Srinivas Pandruvada). - cpufreq-dt driver cleanup (Markus Elfring). - Init fix for the ARM big.LITTLE cpuidle driver (Sudeep Holla). - Generic power domains core code fixes and cleanups (Ulf Hansson). - Operating Performance Points (OPP) core code cleanups and kernel documentation update (Nishanth Menon). - New dabugfs interface to make the list of PM QoS constraints available to user space (Nishanth Menon). - New devfreq driver for Tegra Activity Monitor (Tomeu Vizoso). - New devfreq class (devfreq_event) to provide raw utilization data to devfreq governors (Chanwoo Choi). - Assorted minor fixes and cleanups related to power management (Andreas Ruprecht, Krzysztof Kozlowski, Rickard Strandqvist, Pavel Machek, Todd E Brandt, Wonhong Kwon). - turbostat updates (Len Brown) and cpupower Makefile improvement (Sriram Raghunathan)" * tag 'pm+acpi-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (151 commits) tools/power turbostat: relax dependency on APERF_MSR tools/power turbostat: relax dependency on invariant TSC Merge branch 'pci/host-generic' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci into acpi-resources tools/power turbostat: decode MSR_*_PERF_LIMIT_REASONS tools/power turbostat: relax dependency on root permission ACPI / video: Add disable_native_backlight quirk for Samsung 510R ACPI / PM: Remove unneeded nested #ifdef USB / PM: Remove unneeded #ifdef and associated dead code intel_pstate: provide option to only use intel_pstate with HWP ACPI / EC: Add GPE reference counting debugging messages ACPI / EC: Add query flushing support ACPI / EC: Refine command storm prevention support ACPI / EC: Add command flushing support. ACPI / EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag ACPI: add AMD ACPI2Platform device support for x86 system ACPI / table: remove duplicate NULL check for the handler of acpi_table_parse() ACPI / EC: Update revision due to raw handler mode. ACPI / EC: Reduce ec_poll() by referencing the last register access timestamp. ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode. ACPICA: Events: Enable APIs to allow interrupt/polling adaptive request based GPE handling model ...

tracing: Fix unmapping loop in tracing_mark_write

2015-02-09T23:47:09Z

Commit 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce introduced an array map_pages that contains the addresses returned by kmap_atomic. However, when unmapping those pages, map_pages[0] is unmapped before map_pages[1], breaking the nesting requirement as specified in the documentation for kmap_atomic/kunmap_atomic. This was caught by the highmem debug code present in kunmap_atomic. Fix the loop to do the unmapping properly. Link: http://lkml.kernel.org/r/1418871056-6614-1-git-send-email-markivx@codeaurora.org Cc: stable@vger.kernel.org # 3.5+ Reviewed-by: Stephen Boyd Reported-by: Lime Yang Signed-off-by: Vikram Mulukutla Signed-off-by: Steven Rostedt

tracing: Separate out initializing top level dir from instances

2015-02-02T15:22:34Z

The top level trace array is treated a little different than the instances, as it has to deal with more of the general tracing. The tr->dir is the tracing directory, which is an immutable dentry, where as the tr->dir of instances are the dentry that was created, and can be destroyed later. These should have different functions accessing them. As only tracing_init_dentry() deals with the top level array, fold the code for it into that function, and remove the trace_init_dentry_tr() that was also used by the instances to get their directory dentry. Add a tracing_get_dentry() to just get the tracing dir entry for instances as well as the top level array. Signed-off-by: Steven Rostedt