linux/kernel/trace/trace_kprobe.c, branch v4.1

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

2015-04-14T21:37:47Z

Pull perf changes from Ingo Molnar: "Core kernel changes: - One of the more interesting features in this cycle is the ability to attach eBPF programs (user-defined, sandboxed bytecode executed by the kernel) to kprobes. This allows user-defined instrumentation on a live kernel image that can never crash, hang or interfere with the kernel negatively. (Right now it's limited to root-only, but in the future we might allow unprivileged use as well.) (Alexei Starovoitov) - Another non-trivial feature is per event clockid support: this allows, amongst other things, the selection of different clock sources for event timestamps traced via perf. This feature is sought by people who'd like to merge perf generated events with external events that were measured with different clocks: - cluster wide profiling - for system wide tracing with user-space events, - JIT profiling events etc. Matching perf tooling support is added as well, available via the -k, --clockid parameter to perf record et al. (Peter Zijlstra) Hardware enablement kernel changes: - x86 Intel Processor Trace (PT) support: which is a hardware tracer on steroids, available on Broadwell CPUs. The hardware trace stream is directly output into the user-space ring-buffer, using the 'AUX' data format extension that was added to the perf core to support hardware constraints such as the necessity to have the tracing buffer physically contiguous. This patch-set was developed for two years and this is the result. A simple way to make use of this is to use BTS tracing, the PT driver emulates BTS output - available via the 'intel_bts' PMU. More explicit PT specific tooling support is in the works as well - will probably be ready by 4.2. (Alexander Shishkin, Peter Zijlstra) - x86 Intel Cache QoS Monitoring (CQM) support: this is a hardware feature of Intel Xeon CPUs that allows the measurement and allocation/partitioning of caches to individual workloads. These kernel changes expose the measurement side as a new PMU driver, which exposes various QoS related PMU events. (The partitioning change is work in progress and is planned to be merged as a cgroup extension.) (Matt Fleming, Peter Zijlstra; CPU feature detection by Peter P Waskiewicz Jr) - x86 Intel Haswell LBR call stack support: this is a new Haswell feature that allows the hardware recording of call chains, plus tooling support. To activate this feature you have to enable it via the new 'lbr' call-graph recording option: perf record --call-graph lbr perf report or: perf top --call-graph lbr This hardware feature is a lot faster than stack walk or dwarf based unwinding, but has some limitations: - It reuses the current LBR facility, so LBR call stack and branch record can not be enabled at the same time. - It is only available for user-space callchains. (Yan, Zheng) - x86 Intel Broadwell CPU support and various event constraints and event table fixes for earlier models. (Andi Kleen) - x86 Intel HT CPUs event scheduling workarounds. This is a complex CPU bug affecting the SNB,IVB,HSW families that results in counter value corruption. The mitigation code is automatically enabled and is transparent. (Maria Dimakopoulou, Stephane Eranian) The perf tooling side had a ton of changes in this cycle as well, so I'm only able to list the user visible changes here, in addition to the tooling changes outlined above: User visible changes affecting all tools: - Improve support of compressed kernel modules (Jiri Olsa) - Save DSO loading errno to better report errors (Arnaldo Carvalho de Melo) - Bash completion for subcommands (Yunlong Song) - Add 'I' event modifier for perf_event_attr.exclude_idle bit (Jiri Olsa) - Support missing -f to override perf.data file ownership. (Yunlong Song) - Show the first event with an invalid filter (David Ahern, Arnaldo Carvalho de Melo) User visible changes in individual tools: 'perf data': New tool for converting perf.data to other formats, initially for the CTF (Common Trace Format) from LTTng (Jiri Olsa, Sebastian Siewior) 'perf diff': Add --kallsyms option (David Ahern) 'perf list': Allow listing events with 'tracepoint' prefix (Yunlong Song) Sort the output of the command (Yunlong Song) 'perf kmem': Respect -i option (Jiri Olsa) Print big numbers using thousands' group (Namhyung Kim) Allow -v option (Namhyung Kim) Fix alignment of slab result table (Namhyung Kim) 'perf probe': Support multiple probes on different binaries on the same command line (Masami Hiramatsu) Support unnamed union/structure members data collection. (Masami Hiramatsu) Check kprobes blacklist when adding new events. (Masami Hiramatsu) 'perf record': Teach 'perf record' about perf_event_attr.clockid (Peter Zijlstra) Support recording running/enabled time (Andi Kleen) 'perf sched': Improve the performance of 'perf sched replay' on high CPU core count machines (Yunlong Song) 'perf report' and 'perf top': Allow annotating entries in callchains in the hists browser (Arnaldo Carvalho de Melo) Indicate which callchain entries are annotated in the TUI hists browser (Arnaldo Carvalho de Melo) Add pid/tid filtering to 'report' and 'script' commands (David Ahern) Consider PERF_RECORD_ events with cpumode == 0 in 'perf top', removing one cause of long term memory usage buildup, i.e. not processing PERF_RECORD_EXIT events (Arnaldo Carvalho de Melo) 'perf stat': Report unsupported events properly (Suzuki K. Poulose) Output running time and run/enabled ratio in CSV mode (Andi Kleen) 'perf trace': Handle legacy syscalls tracepoints (David Ahern, Arnaldo Carvalho de Melo) Only insert blank duration bracket when tracing syscalls (Arnaldo Carvalho de Melo) Filter out the trace pid when no threads are specified (Arnaldo Carvalho de Melo) Dump stack on segfaults (Arnaldo Carvalho de Melo) No need to explicitely enable evsels for workload started from perf, let it be enabled via perf_event_attr.enable_on_exec, removing some events that take place in the 'perf trace' before a workload is really started by it. (Arnaldo Carvalho de Melo) Allow mixing with tracepoints and suppressing plain syscalls. (Arnaldo Carvalho de Melo) There's also been a ton of infrastructure work done, such as the split-out of perf's build system into tools/build/ and other changes - see the shortlog and changelog for details" * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (358 commits) perf/x86/intel/pt: Clean up the control flow in pt_pmu_hw_init() perf evlist: Fix type for references to data_head/tail perf probe: Check the orphaned -x option perf probe: Support multiple probes on different binaries perf buildid-list: Fix segfault when show DSOs with hits perf tools: Fix cross-endian analysis perf tools: Fix error path to do closedir() when synthesizing threads perf tools: Fix synthesizing fork_event.ppid for non-main thread perf tools: Add 'I' event modifier for exclude_idle bit perf report: Don't call map__kmap if map is NULL. perf tests: Fix attr tests perf probe: Fix ARM 32 building error perf tools: Merge all perf_event_attr print functions perf record: Add clockid parameter perf sched replay: Use replay_repeat to calculate the runavg of cpu usage instead of the default value 10 perf sched replay: Support using -f to override perf.data file ownership perf sched replay: Fix the EMFILE error caused by the limitation of the maximum open files perf sched replay: Handle the dead halt of sem_wait when create_tasks() fails for any task perf sched replay: Fix the segmentation fault problem caused by pr_err in threads perf sched replay: Realloc the memory of pid_to_task stepwise to adapt to the different pid_max configurations ...

Merge tag 'trace-v4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2015-04-14T17:49:03Z

Pull tracing updates from Steven Rostedt: "Some clean ups and small fixes, but the biggest change is the addition of the TRACE_DEFINE_ENUM() macro that can be used by tracepoints. Tracepoints have helper functions for the TP_printk() called __print_symbolic() and __print_flags() that lets a numeric number be displayed as a a human comprehensible text. What is placed in the TP_printk() is also shown in the tracepoint format file such that user space tools like perf and trace-cmd can parse the binary data and express the values too. Unfortunately, the way the TRACE_EVENT() macro works, anything placed in the TP_printk() will be shown pretty much exactly as is. The problem arises when enums are used. That's because unlike macros, enums will not be changed into their values by the C pre-processor. Thus, the enum string is exported to the format file, and this makes it useless for user space tools. The TRACE_DEFINE_ENUM() solves this by converting the enum strings in the TP_printk() format into their number, and that is what is shown to user space. For example, the tracepoint tlb_flush currently has this in its format file: __print_symbolic(REC->reason, { TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" }, { TLB_REMOTE_SHOOTDOWN, "remote shootdown" }, { TLB_LOCAL_SHOOTDOWN, "local shootdown" }, { TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" }) After adding: TRACE_DEFINE_ENUM(TLB_FLUSH_ON_TASK_SWITCH); TRACE_DEFINE_ENUM(TLB_REMOTE_SHOOTDOWN); TRACE_DEFINE_ENUM(TLB_LOCAL_SHOOTDOWN); TRACE_DEFINE_ENUM(TLB_LOCAL_MM_SHOOTDOWN); Its format file will contain this: __print_symbolic(REC->reason, { 0, "flush on task switch" }, { 1, "remote shootdown" }, { 2, "local shootdown" }, { 3, "local mm shootdown" })" * tag 'trace-v4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (27 commits) tracing: Add enum_map file to show enums that have been mapped writeback: Export enums used by tracepoint to user space v4l: Export enums used by tracepoints to user space SUNRPC: Export enums in tracepoints to user space mm: tracing: Export enums in tracepoints to user space irq/tracing: Export enums in tracepoints to user space f2fs: Export the enums in the tracepoints to userspace net/9p/tracing: Export enums in tracepoints to userspace x86/tlb/trace: Export enums in used by tlb_flush tracepoint tracing/samples: Update the trace-event-sample.h with TRACE_DEFINE_ENUM() tracing: Allow for modules to convert their enums to values tracing: Add TRACE_DEFINE_ENUM() macro to map enums to their values tracing: Update trace-event-sample with TRACE_SYSTEM_VAR documentation tracing: Give system name a pointer brcmsmac: Move each system tracepoints to their own header iwlwifi: Move each system tracepoints to their own header mac80211: Move message tracepoints to their own header tracing: Add TRACE_SYSTEM_VAR to xhci-hcd tracing: Add TRACE_SYSTEM_VAR to kvm-s390 tracing: Add TRACE_SYSTEM_VAR to intel-sst ...

Merge tag 'trace-4.1-tracefs' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2015-04-14T17:22:29Z

Pull tracefs from Steven Rostedt: "This adds the new tracefs file system. This has been in linux-next for more than one release, as I had it ready for the 4.0 merge window, but a last minute thing that needed to go into Linux first had to be done. That was that perf hard coded the file system number when reading /sys/kernel/debugfs/tracing directory making sure that the path had the debugfs mount # before it would parse the tracing file. This broke other use cases of perf, and the check is removed. Now when mounting /sys/kernel/debug, tracefs is automatically mounted in /sys/kernel/debug/tracing such that old tools will still see that path as expected. But now system admins can mount tracefs directly and not need to mount debugfs, which can expose security issues. A new directory is created when tracefs is configured such that system admins can now mount it separately (/sys/kernel/tracing)" * tag 'trace-4.1-tracefs' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Have mkdir and rmdir be part of tracefs tracefs: Add directory /sys/kernel/tracing tracing: Automatically mount tracefs on debugfs/tracing tracing: Convert the tracing facility over to use tracefs tracefs: Add new tracefs file system tracing: Create cmdline tracer options on tracing fs init tracing: Only create tracer options files if directory exists debugfs: Provide a file creation function that also takes an initial size

tracing, perf: Implement BPF programs attached to kprobes

2015-04-02T11:25:49Z

BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov Reviewed-by: Steven Rostedt Reviewed-by: Masami Hiramatsu Cc: Andrew Morton Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Daniel Borkmann Cc: David S. Miller Cc: Jiri Olsa Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar

tracing: Add kprobe flag

2015-04-02T11:25:49Z

add TRACE_EVENT_FL_KPROBE flag to differentiate kprobe type of tracepoints, since bpf programs can only be attached to kprobe type of PERF_TYPE_TRACEPOINT perf events. Signed-off-by: Alexei Starovoitov Reviewed-by: Steven Rostedt Reviewed-by: Masami Hiramatsu Cc: Andrew Morton Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Daniel Borkmann Cc: David S. Miller Cc: Jiri Olsa Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1427312966-8434-3-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar

trace: Don't use __weak in header files

2015-03-25T12:57:23Z

The commit that added a check for this to checkpatch says: "Using weak declarations can have unintended link defects. The __weak on the declaration causes non-weak definitions to become weak." In this case, when a PowerPC kernel is built with CONFIG_KPROBE_EVENT but not CONFIG_UPROBE_EVENT, it generates the following warning: WARNING: 1 bad relocations c0000000014f2190 R_PPC64_ADDR64 uprobes_fetch_type_table This is fixed by passing the fetch_table arrays to traceprobe_parse_probe_arg() which also means that they can never be NULL. Link: http://lkml.kernel.org/r/20150312165834.4482cb48@canb.auug.org.au Acked-by: Masami Hiramatsu Signed-off-by: Stephen Rothwell Signed-off-by: Steven Rostedt

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

tracing: Convert the tracing facility over to use tracefs

2015-02-03T17:48:41Z

debugfs was fine for the tracing facility as a quick way to get an interface. Now that tracing has matured, it should separate itself from debugfs such that it can be mounted separately without needing to mount all of debugfs with it. That is, users resist using tracing because it requires mounting debugfs. Having tracing have its own file system lets users get the features of tracing without needing to bring in the rest of the kernel's debug infrastructure. Another reason for tracefs is that debubfs does not support mkdir. Currently, to create instances, one does a mkdir in the tracing/instance directory. This is implemented via a hack that forces debugfs to do something it is not intended on doing. By converting over to tracefs, this hack can be removed and mkdir can be properly implemented. This patch does not address this yet, but it lays the ground work for that to be done. Signed-off-by: Steven Rostedt

tracing: Use IS_ERR() check for return value of tracing_init_dentry()

2015-01-22T16:19:49Z

tracing_init_dentry() will soon return NULL as a valid pointer for the top level tracing directroy. NULL can not be used as an error value. Instead, switch to ERR_PTR() and check the return status with IS_ERR(). Signed-off-by: Steven Rostedt

perf: Avoid horrible stack usage

2015-01-14T14:11:45Z

Both Linus (most recent) and Steve (a while ago) reported that perf related callbacks have massive stack bloat. The problem is that software events need a pt_regs in order to properly report the event location and unwind stack. And because we could not assume one was present we allocated one on stack and filled it with minimal bits required for operation. Now, pt_regs is quite large, so this is undesirable. Furthermore it turns out that most sites actually have a pt_regs pointer available, making this even more onerous, as the stack space is pointless waste. This patch addresses the problem by observing that software events have well defined nesting semantics, therefore we can use static per-cpu storage instead of on-stack. Linus made the further observation that all but the scheduler callers of perf_sw_event() have a pt_regs available, so we change the regular perf_sw_event() to require a valid pt_regs (where it used to be optional) and add perf_sw_event_sched() for the scheduler. We have a scheduler specific call instead of a more generic _noregs() like construct because we can assume non-recursion from the scheduler and thereby simplify the code further (_noregs would have to put the recursion context call inline in order to assertain which __perf_regs element to use). One last note on the implementation of perf_trace_buf_prepare(); we allow .regs = NULL for those cases where we already have a pt_regs pointer available and do not need another. Reported-by: Linus Torvalds Reported-by: Steven Rostedt Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Javi Merino Cc: Linus Torvalds Cc: Mathieu Desnoyers Cc: Oleg Nesterov Cc: Paul Mackerras Cc: Petr Mladek Cc: Steven Rostedt Cc: Tom Zanussi Cc: Vaibhav Nagarnaik Link: http://lkml.kernel.org/r/20141216115041.GW3337@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar