linux/Documentation/trace, branch v5.5

Merge tag 'docs-5.5a' of git://git.lwn.net/linux

2019-12-02T19:51:02Z

Pull Documentation updates from Jonathan Corbet: "Here are the main documentation changes for 5.5: - Various kerneldoc script enhancements. - More RST conversions; those are slowing down as we run out of things to convert, but we're a ways from done still. - Dan's "maintainer profile entry" work landed at last. Now we just need to get maintainers to fill in the profiles... - A reworking of the parallel build setup to work better with a variety of systems (and to not take over huge systems entirely in particular). - The MAINTAINERS file is now converted to RST during the build. Hopefully nobody ever tries to print this thing, or they will need to load a lot of paper. - A script and documentation making it easy for maintainers to add Link: tags at commit time. Also included is the removal of a bunch of spurious CR characters" * tag 'docs-5.5a' of git://git.lwn.net/linux: (91 commits) docs: remove a bunch of stray CRs docs: fix up the maintainer profile document libnvdimm, MAINTAINERS: Maintainer Entry Profile Maintainer Handbook: Maintainer Entry Profile MAINTAINERS: Reclaim the P: tag for Maintainer Entry Profile docs, parallelism: Rearrange how jobserver reservations are made docs, parallelism: Do not leak blocking mode to other readers docs, parallelism: Fix failure path and add comment Documentation: Remove bootmem_debug from kernel-parameters.txt Documentation: security: core.rst: fix warnings Documentation/process/howto/kokr: Update for 4.x -> 5.x versioning Documentation/translation: Use Korean for Korean translation title docs/memory-barriers.txt: Remove remaining references to mmiowb() docs/memory-barriers.txt/kokr: Update I/O section to be clearer about CPU vs thread docs/memory-barriers.txt/kokr: Fix style, spacing and grammar in I/O section Documentation/kokr: Kill all references to mmiowb() docs/memory-barriers.txt/kokr: Rewrite "KERNEL I/O BARRIER EFFECTS" section docs: Add initial documentation for devfreq Documentation: Document how to get links with git am docs: Add request_irq() documentation ...

Merge tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2019-11-27T19:42:01Z

Pull tracing updates from Steven Rostedt: "New tracing features: - New PERMANENT flag to ftrace_ops when attaching a callback to a function. As /proc/sys/kernel/ftrace_enabled when set to zero will disable all attached callbacks in ftrace, this has a detrimental impact on live kernel tracing, as it disables all that it patched. If a ftrace_ops is registered to ftrace with the PERMANENT flag set, it will prevent ftrace_enabled from being disabled, and if ftrace_enabled is already disabled, it will prevent a ftrace_ops with PREMANENT flag set from being registered. - New register_ftrace_direct(). As eBPF would like to register its own trampolines to be called by the ftrace nop locations directly, without going through the ftrace trampoline, this function has been added. This allows for eBPF trampolines to live along side of ftrace, perf, kprobe and live patching. It also utilizes the ftrace enabled_functions file that keeps track of functions that have been modified in the kernel, to allow for security auditing. - Allow for kernel internal use of ftrace instances. Subsystems in the kernel can now create and destroy their own tracing instances which allows them to have their own tracing buffer, and be able to record events without worrying about other users from writing over their data. - New seq_buf_hex_dump() that lets users use the hex_dump() in their seq_buf usage. - Notifications now added to tracing_max_latency to allow user space to know when a new max latency is hit by one of the latency tracers. - Wider spread use of generic compare operations for use of bsearch and friends. - More synthetic event fields may be defined (32 up from 16) - Use of xarray for architectures with sparse system calls, for the system call trace events. This along with small clean ups and fixes" * tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (51 commits) tracing: Enable syscall optimization for MIPS tracing: Use xarray for syscall trace events tracing: Sample module to demonstrate kernel access to Ftrace instances. tracing: Adding new functions for kernel access to Ftrace instances tracing: Fix Kconfig indentation ring-buffer: Fix typos in function ring_buffer_producer ftrace: Use BIT() macro ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not configured ftrace: Rename ftrace_graph_stub to ftrace_stub_graph ftrace: Add a helper function to modify_ftrace_direct() to allow arch optimization ftrace: Add helper find_direct_entry() to consolidate code ftrace: Add another check for match in register_ftrace_direct() ftrace: Fix accounting bug with direct->count in register_ftrace_direct() ftrace/selftests: Fix spelling mistake "wakeing" -> "waking" tracing: Increase SYNTH_FIELDS_MAX for synthetic_events ftrace/samples: Add a sample module that implements modify_ftrace_direct() ftrace: Add modify_ftrace_direct() tracing: Add missing "inline" in stub function of latency_fsnotify() tracing: Remove stray tab in TRACE_EVAL_MAP_FILE's help text tracing: Use seq_buf_hex_dump() to dump buffers ...

intel_th: Document software sinks

2019-11-14T06:48:49Z

Add documentation for the software sinks API of the MSU driver and the msu-sink module in particular. Signed-off-by: Alexander Shishkin Link: https://lore.kernel.org/r/20191114064201.43089-3-alexander.shishkin@linux.intel.com Signed-off-by: Greg Kroah-Hartman

tracing: Use CONFIG_PREEMPTION

2019-11-13T14:37:28Z

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same functionality which today depends on CONFIG_PREEMPT. Add additional header output for PREEMPT_RT. Link: http://lkml.kernel.org/r/20191015191821.11479-34-bigeasy@linutronix.de Cc: Ingo Molnar Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (VMware)

coresight: etm4x: docs: Adds detailed document for programming etm4x.

2019-11-07T20:17:26Z

Add in detailed programmers reference for users wanting to program the CoreSight ETM 4.x driver using sysfs. Signed-off-by: Mike Leach Reviewed-by: Mathieu Poirier Signed-off-by: Jonathan Corbet

coresight: docs: Create common sub-directory for coresight trace.

2019-11-07T20:17:26Z

There are two files in the Documentation/trace directory relating to coresight, with more to follow, so create a Documentation/trace/coresight directory and move existing files there. Fixup index to reference new location. Update MAINTAINERS to reference this sub-directory rather than the individual files. Signed-off-by: Mike Leach Reviewed-by: Mathieu Poirier Signed-off-by: Jonathan Corbet

ftrace: Introduce PERMANENT ftrace_ops flag

2019-11-04T14:33:15Z

Livepatch uses ftrace for redirection to new patched functions. It means that if ftrace is disabled, all live patched functions are disabled as well. Toggling global 'ftrace_enabled' sysctl thus affect it directly. It is not a problem per se, because only administrator can set sysctl values, but it still may be surprising. Introduce PERMANENT ftrace_ops flag to amend this. If the FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be disabled by disabling ftrace_enabled. Equally, a callback with the flag set cannot be registered if ftrace_enabled is disabled. Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz Reviewed-by: Petr Mladek Reviewed-by: Kamalesh Babulal Signed-off-by: Miroslav Benes Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2019-09-20T18:19:48Z

Pull tracing updates from Steven Rostedt: - Addition of multiprobes to kprobe and uprobe events (allows for more than one probe attached to the same location) - Addition of adding immediates to probe parameters - Clean up of the recordmcount.c code. This brings us closer to merging recordmcount into objtool, and reuse code. - Other small clean ups * tag 'trace-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits) selftests/ftrace: Update kprobe event error testcase tracing/probe: Reject exactly same probe event tracing/probe: Fix to allow user to enable events on unloaded modules selftests/ftrace: Select an existing function in kprobe_eventname test tracing/kprobe: Fix NULL pointer access in trace_porbe_unlink() tracing: Make sure variable reference alias has correct var_ref_idx tracing: Be more clever when dumping hex in __print_hex() ftrace: Simplify ftrace hash lookup code in clear_func_from_hash() tracing: Add "gfp_t" support in synthetic_events tracing: Rename tracing_reset() to tracing_reset_cpu() tracing: Document the stack trace algorithm in the comments tracing/arm64: Have max stack tracer handle the case of return address after data recordmcount: Clarify what cleanup() does recordmcount: Remove redundant cleanup() calls recordmcount: Kernel style formatting recordmcount: Kernel style function signature formatting recordmcount: Rewrite error/success handling selftests/ftrace: Add syntax error test for multiprobe selftests/ftrace: Add syntax error test for immediates selftests/ftrace: Add a testcase for kprobe multiprobe event ...

docs: ftrace: clarify when tracing is disabled by the trace file

2019-09-02T13:14:53Z

The current text could mislead the user into believing that only read() disables tracing. Clarify that any open() call that requests read access disables tracing. Link: https://lkml.kernel.org/r/CAADnVQ+hU6QOC_dPmpjnuv=9g4SQEeaMEMqXOS2WpMj=q=LdiQ@mail.gmail.com Signed-off-by: Peter Wu Acked-by: Steven Rostedt (VMware) Signed-off-by: Jonathan Corbet

tracing/probe: Add immediate parameter support

2019-08-31T16:19:39Z

Add immediate value parameter (\1234) support to probe events. This allows you to specify an immediate (or dummy) parameter instead of fetching from memory or register. This feature looks odd, but imagine when you put a probe on a code to trace some data. If the code is compiled into 2 instructions and 1 instruction has a value but other has nothing since it is optimized out. In that case, you can not fold those into one event, even if ftrace supported multiple probes on one event. With this feature, you can set a dummy value like foo=\deadbeef instead of something like foo=%di. Link: http://lkml.kernel.org/r/156095690733.28024.13258186548822649469.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)