New:
- The Real Time Linux Analysis (RTLA) tool is added to the tools directory.
- Can safely filter on user space pointers with: field.ustring ~ "match-string"
- eprobes can now be filtered like any other event.
- trace_marker(_raw) now uses stream_open() to allow multiple threads to safely
write to it. Note, this could possibly break existing user space, but we will
not know until we hear about it, and then can revert the change if need be.
- New field in events to display when bottom halfs are disabled.
- Sorting of the ftrace functions are now done at compile time instead of
at bootup.
Infrastructure changes to support future efforts:
- Added __rel_loc type for trace events. Similar to __data_loc but the offset
to the dynamic data is based off of the location of the descriptor and not
the beginning of the event. Needed for user defined events.
- Some simplification of event trigger code.
- Make synthetic events process its callback better to not hinder other
event callbacks that are registered. Needed for user defined events.
And other small fixes and clean ups.
-
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Merge tag 'trace-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"New:
- The Real Time Linux Analysis (RTLA) tool is added to the tools
directory.
- Can safely filter on user space pointers with: field.ustring ~
"match-string"
- eprobes can now be filtered like any other event.
- trace_marker(_raw) now uses stream_open() to allow multiple threads
to safely write to it. Note, this could possibly break existing
user space, but we will not know until we hear about it, and then
can revert the change if need be.
- New field in events to display when bottom halfs are disabled.
- Sorting of the ftrace functions are now done at compile time
instead of at bootup.
Infrastructure changes to support future efforts:
- Added __rel_loc type for trace events. Similar to __data_loc but
the offset to the dynamic data is based off of the location of the
descriptor and not the beginning of the event. Needed for user
defined events.
- Some simplification of event trigger code.
- Make synthetic events process its callback better to not hinder
other event callbacks that are registered. Needed for user defined
events.
And other small fixes and cleanups"
* tag 'trace-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (50 commits)
tracing: Add ustring operation to filtering string pointers
rtla: Add rtla timerlat hist documentation
rtla: Add rtla timerlat top documentation
rtla: Add rtla timerlat documentation
rtla: Add rtla osnoise hist documentation
rtla: Add rtla osnoise top documentation
rtla: Add rtla osnoise man page
rtla: Add Documentation
rtla/timerlat: Add timerlat hist mode
rtla: Add timerlat tool and timelart top mode
rtla/osnoise: Add the hist mode
rtla/osnoise: Add osnoise top mode
rtla: Add osnoise tool
rtla: Helper functions for rtla
rtla: Real-Time Linux Analysis tool
tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails
tracing: Remove duplicate warnings when calling trace_create_file()
tracing/kprobes: 'nmissed' not showed correctly for kretprobe
tracing: Add test for user space strings when filtering on string pointers
tracing: Have syscall trace events use trace_event_buffer_lock_reserve()
...
Disabling only bottom halves via local_bh_disable() disables also
preemption but this remains invisible to tracing. On a CONFIG_PREEMPT
kernel one might wonder why there is no scheduling happening despite the
N flag in the trace. The reason might be the a rcu_read_lock_bh()
section.
Add a 'b' to the tracing output if in task context with disabled bottom
halves.
Link: https://lkml.kernel.org/r/YbcbtdtC/bjCKo57@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
With the new osnoise tracer, we are seeing the below splat:
Kernel attempted to read user page (c7d880000) - exploit attempt? (uid: 0)
BUG: Unable to handle kernel data access on read at 0xc7d880000
Faulting instruction address: 0xc0000000002ffa10
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
...
NIP [c0000000002ffa10] __trace_array_vprintk.part.0+0x70/0x2f0
LR [c0000000002ff9fc] __trace_array_vprintk.part.0+0x5c/0x2f0
Call Trace:
[c0000008bdd73b80] [c0000000001c49cc] put_prev_task_fair+0x3c/0x60 (unreliable)
[c0000008bdd73be0] [c000000000301430] trace_array_printk_buf+0x70/0x90
[c0000008bdd73c00] [c0000000003178b0] trace_sched_switch_callback+0x250/0x290
[c0000008bdd73c90] [c000000000e70d60] __schedule+0x410/0x710
[c0000008bdd73d40] [c000000000e710c0] schedule+0x60/0x130
[c0000008bdd73d70] [c000000000030614] interrupt_exit_user_prepare_main+0x264/0x270
[c0000008bdd73de0] [c000000000030a70] syscall_exit_prepare+0x150/0x180
[c0000008bdd73e10] [c00000000000c174] system_call_vectored_common+0xf4/0x278
osnoise tracer on ppc64le is triggering osnoise_taint() for negative
duration in get_int_safe_duration() called from
trace_sched_switch_callback()->thread_exit().
The problem though is that the check for a valid trace_percpu_buffer is
incorrect in get_trace_buf(). The check is being done after calculating
the pointer for the current cpu, rather than on the main percpu pointer.
Fix the check to be against trace_percpu_buffer.
Link: https://lkml.kernel.org/r/a920e4272e0b0635cf20c444707cbce1b2c8973d.1640255304.git.naveen.n.rao@linux.vnet.ibm.com
Cc: stable@vger.kernel.org
Fixes: e2ace00117 ("tracing: Choose static tp_printk buffer by explicit nesting count")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The tracing marker files are write-only streams with no meaningful
concept of file position. Using stream_open() to mark them as
stream-link indicates this and has the added advantage that a single
file descriptor can now be used from multiple threads without contention
thanks to clearing FMODE_ATOMIC_POS.
Note that this has the potential to break existing userspace by since
both lseek(2) and pwrite(2) will now return ESPIPE when previously lseek
would have updated the stored offset and pwrite would have appended to
the trace. A survey of libtracefs and several other projects found to
use trace_marker(_raw) [1][2][3] suggests that everyone limits
themselves to calling write(2) and close(2) on these file descriptors so
there is a good chance this will go unnoticed and the benefits of
reduced overhead and lock contention seem worth the risk.
[1] https://github.com/google/perfetto
[2] https://github.com/intel/media-driver/
[3] https://w1.fi/cgit/hostap/
Link: https://lkml.kernel.org/r/20211207142558.347029-1-john@metanate.com
Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
In case trace_event_buffer_lock_reserve() is called with preemption
enabled, the algorithm that defines the usage of the per cpu filter buffer
may fail if the task schedules to another CPU after determining which
buffer it will use.
Disable preemption when using the filter buffer. And because that same
buffer must be used throughout the call, keep preemption disabled until
the filter buffer is released.
This will also keep the semantics between the use case of when the filter
buffer is used, and when the ring buffer itself is used, as that case also
disables preemption until the ring buffer is released.
Link: https://lkml.kernel.org/r/20211130024318.880190623@goodmis.org
[ Fixed warning of assignment in if statement
Reported-by: kernel test robot <lkp@intel.com> ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The value read by this_cpu_read() is used later and its use is expected to
stay on the same CPU as being read. But this_cpu_read() does not warn if
it is called without preemption disabled, where as __this_cpu_read() will
check if preemption is disabled on CONFIG_DEBUG_PREEMPT
Currently all callers have preemption disabled, but there may be new
callers in the future that may not.
Link: https://lkml.kernel.org/r/20211130024318.698165354@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
If trace_seq becomes full, trace_seq_vprintf() no longer consumes
arguments from va_list, making va_list out of sync with format
processing by trace_check_vprintf().
This causes va_arg() in trace_check_vprintf() to return wrong
positional argument, which results into a WARN_ON_ONCE() hit.
ftrace_stress_test from LTP triggers this situation.
Fix it by explicitly avoiding further use if va_list at the point
when it's consistency can no longer be guaranteed.
Link: https://lkml.kernel.org/r/20211118145516.13219-1-nikita.yushchenko@virtuozzo.com
Signed-off-by: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.
Use memset_startat() to avoid confusing memset() about writing beyond
the target struct member.
Link: https://lkml.kernel.org/r/20211118202217.1285588-1-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
- osnoise and timerlat updates that will work with the RTLA tool (Real-Time
Linux Analysis). Specifically it disconnects the work load (threads
that look for latency) from the tracing instances attached to them,
allowing for more than one instance to retrieve data from the work load.
- Optimization on division in the trace histogram trigger code to use shift
and multiply when possible. Also added documentation.
- Fix prototype to my_direct_func in direct ftrace trampoline sample code.
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Merge tag 'trace-v5.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull more tracing updates from Steven Rostedt:
- osnoise and timerlat updates that will work with the RTLA tool
(Real-Time Linux Analysis).
Specifically it disconnects the work load (threads that look for
latency) from the tracing instances attached to them, allowing for
more than one instance to retrieve data from the work load.
- Optimization on division in the trace histogram trigger code to use
shift and multiply when possible. Also added documentation.
- Fix prototype to my_direct_func in direct ftrace trampoline sample
code.
* tag 'trace-v5.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace/samples: Add missing prototype for my_direct_func
tracing/selftests: Add tests for hist trigger expression parsing
tracing/histogram: Document hist trigger variables
tracing/histogram: Update division by 0 documentation
tracing/histogram: Optimize division by constants
tracing/osnoise: Remove PREEMPT_RT ifdefs from inside functions
tracing/osnoise: Remove STACKTRACE ifdefs from inside functions
tracing/osnoise: Allow multiple instances of the same tracer
tracing/osnoise: Remove TIMERLAT ifdefs from inside functions
tracing/osnoise: Support a list of trace_array *tr
tracing/osnoise: Use start/stop_per_cpu_kthreads() on osnoise_cpus_write()
tracing/osnoise: Split workload start from the tracer start
tracing/osnoise: Improve comments about barrier need for NMI callbacks
tracing/osnoise: Do not follow tracing_cpumask
- kprobes: Restructured stack unwinder to show properly on x86 when a stack
dump happens from a kretprobe callback.
- Fix to bootconfig parsing
- Have tracefs allow owner and group permissions by default (only denying
others). There's been pressure to allow non root to tracefs in a
controlled fashion, and using groups is probably the safest.
- Bootconfig memory managament updates.
- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.
- Allow perf to be traced by function tracer.
- Rewrite of function graph tracer to be a callback from the function tracer
instead of having its own trampoline (this change will happen on an arch
by arch basis, and currently only x86_64 implements it).
- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.
- Allow histogram triggers to add variables that can perform calculations
against the event's fields.
- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent warnings
from the compiler.
- Extend histogram triggers to key off of variables.
- Have trace recursion use bit magic to determine preempt context over if
branches.
- Have trace recursion disable preemption as all use cases do anyway.
- Added testing for verification of tracing utilities.
- Various small clean ups and fixes.
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Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- kprobes: Restructured stack unwinder to show properly on x86 when a
stack dump happens from a kretprobe callback.
- Fix to bootconfig parsing
- Have tracefs allow owner and group permissions by default (only
denying others). There's been pressure to allow non root to tracefs
in a controlled fashion, and using groups is probably the safest.
- Bootconfig memory managament updates.
- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.
- Allow perf to be traced by function tracer.
- Rewrite of function graph tracer to be a callback from the function
tracer instead of having its own trampoline (this change will happen
on an arch by arch basis, and currently only x86_64 implements it).
- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.
- Allow histogram triggers to add variables that can perform
calculations against the event's fields.
- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent
warnings from the compiler.
- Extend histogram triggers to key off of variables.
- Have trace recursion use bit magic to determine preempt context over
if branches.
- Have trace recursion disable preemption as all use cases do anyway.
- Added testing for verification of tracing utilities.
- Various small clean ups and fixes.
* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
tracing/histogram: Fix semicolon.cocci warnings
tracing/histogram: Fix documentation inline emphasis warning
tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
tracing: Show size of requested perf buffer
bootconfig: Initialize ret in xbc_parse_tree()
ftrace: do CPU checking after preemption disabled
ftrace: disable preemption when recursion locked
tracing/histogram: Document expression arithmetic and constants
tracing/histogram: Optimize division by a power of 2
tracing/histogram: Covert expr to const if both operands are constants
tracing/histogram: Simplify handling of .sym-offset in expressions
tracing: Fix operator precedence for hist triggers expression
tracing: Add division and multiplication support for hist triggers
tracing: Add support for creating hist trigger variables from literal
selftests/ftrace: Stop tracing while reading the trace file by default
MAINTAINERS: Update KPROBES and TRACING entries
test_kprobes: Move it from kernel/ to lib/
docs, kprobes: Remove invalid URL and add new reference
samples/kretprobes: Fix return value if register_kretprobe() failed
lib/bootconfig: Fix the xbc_get_info kerneldoc
...
When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.
As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.
Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The compiler warns when the data are actually unused:
kernel/trace/trace.c:1712:13: error: ‘trace_create_maxlat_file’ defined but not used [-Werror=unused-function]
1712 | static void trace_create_maxlat_file(struct trace_array *tr,
| ^~~~~~~~~~~~~~~~~~~~~~~~
[Why]
CONFIG_HWLAT_TRACER=n, CONFIG_TRACER_MAX_TRACE=n, CONFIG_OSNOISE_TRACER=y
gcc report warns.
[How]
Now trace_create_maxlat_file will only take effect when
CONFIG_HWLAT_TRACER=y or CONFIG_TRACER_MAX_TRACE=y. In fact, after
adding osnoise trace, it also needs to take effect.
Link: https://lore.kernel.org/all/c1d9e328-ad7c-920b-6c24-9e1598a6421c@infradead.org/
Link: https://lkml.kernel.org/r/20210922025122.3268022-1-liu.yun@linux.dev
Fixes: bce29ac9ce ("trace: Add osnoise tracer")
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Instead of having the logic that does trace_pid_list open coded, wrap it in
abstract functions. This will allow a rewrite of the logic that implements
the trace_pid_list without affecting the users.
Note, this causes a change in behavior. Every time a pid is written into
the set_*_pid file, it creates a new list and uses RCU to update it. If
pid_max is lowered, but there was a pid currently in the list that was
higher than pid_max, those pids will now be removed on updating the list.
The old behavior kept that from happening.
The rewrite of the pid_list logic will no longer depend on pid_max,
and will return the old behavior.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
- Add migrate-disable counter to tracing header
- Fix error handling in event probes
- Fix missed unlock in osnoise in error path
- Fix merge issue with tools/bootconfig
- Clean up bootconfig data when init memory is removed
- Fix bootconfig to loop only on subkeys
- Have kernel command lines override bootconfig options
- Increase field counts for synthetic events
- Have histograms dynamic allocate event elements to save space
- Fixes in testing and documentation
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Merge tag 'trace-v5.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull more tracing updates from Steven Rostedt:
- Add migrate-disable counter to tracing header
- Fix error handling in event probes
- Fix missed unlock in osnoise in error path
- Fix merge issue with tools/bootconfig
- Clean up bootconfig data when init memory is removed
- Fix bootconfig to loop only on subkeys
- Have kernel command lines override bootconfig options
- Increase field counts for synthetic events
- Have histograms dynamic allocate event elements to save space
- Fixes in testing and documentation
* tag 'trace-v5.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing/boot: Fix to loop on only subkeys
selftests/ftrace: Exclude "(fault)" in testing add/remove eprobe events
tracing: Dynamically allocate the per-elt hist_elt_data array
tracing: synth events: increase max fields count
tools/bootconfig: Show whole test command for each test case
bootconfig: Fix missing return check of xbc_node_compose_key function
tools/bootconfig: Fix tracing_on option checking in ftrace2bconf.sh
docs: bootconfig: Add how to use bootconfig for kernel parameters
init/bootconfig: Reorder init parameter from bootconfig and cmdline
init: bootconfig: Remove all bootconfig data when the init memory is removed
tracing/osnoise: Fix missed cpus_read_unlock() in start_per_cpu_kthreads()
tracing: Fix some alloc_event_probe() error handling bugs
tracing: Add migrate-disabled counter to tracing output.
- Simplifying the Kconfig use of FTRACE and TRACE_IRQFLAGS_SUPPORT
- bootconfig now can start histograms
- bootconfig supports group/all enabling
- histograms now can put values in linear size buckets
- execnames can be passed to synthetic events
- Introduction of "event probes" that attach to other events and
can retrieve data from pointers of fields, or record fields
as different types (a pointer to a string as a string instead
of just a hex number)
- Various fixes and clean ups
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Merge tag 'trace-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- simplify the Kconfig use of FTRACE and TRACE_IRQFLAGS_SUPPORT
- bootconfig can now start histograms
- bootconfig supports group/all enabling
- histograms now can put values in linear size buckets
- execnames can be passed to synthetic events
- introduce "event probes" that attach to other events and can retrieve
data from pointers of fields, or record fields as different types (a
pointer to a string as a string instead of just a hex number)
- various fixes and clean ups
* tag 'trace-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (35 commits)
tracing/doc: Fix table format in histogram code
selftests/ftrace: Add selftest for testing duplicate eprobes and kprobes
selftests/ftrace: Add selftest for testing eprobe events on synthetic events
selftests/ftrace: Add test case to test adding and removing of event probe
selftests/ftrace: Fix requirement check of README file
selftests/ftrace: Add clear_dynamic_events() to test cases
tracing: Add a probe that attaches to trace events
tracing/probes: Reject events which have the same name of existing one
tracing/probes: Have process_fetch_insn() take a void * instead of pt_regs
tracing/probe: Change traceprobe_set_print_fmt() to take a type
tracing/probes: Use struct_size() instead of defining custom macros
tracing/probes: Allow for dot delimiter as well as slash for system names
tracing/probe: Have traceprobe_parse_probe_arg() take a const arg
tracing: Have dynamic events have a ref counter
tracing: Add DYNAMIC flag for dynamic events
tracing: Replace deprecated CPU-hotplug functions.
MAINTAINERS: Add an entry for os noise/latency
tracepoint: Fix kerneldoc comments
bootconfig/tracing/ktest: Update ktest example for boot-time tracing
tools/bootconfig: Use per-group/all enable option in ftrace2bconf script
...
migrate_disable() forbids task migration to another CPU. It is available
since v5.11 and has already users such as highmem or BPF. It is useful
to observe this task state in tracing which already has other states
like the preemption counter.
Instead of adding the migrate disable counter as a new entry to struct
trace_entry, which would extend the whole struct by four bytes, it is
squashed into the preempt-disable counter. The lower four bits represent
the preemption counter, the upper four bits represent the migrate
disable counter. Both counter shouldn't exceed 15 but if they do, there
is a safety net which caps the value at 15.
Add the migrate-disable counter to the trace entry so it shows up in the
trace. Due to the users mentioned above, it is already possible to
observe it:
| bash-1108 [000] ...21 73.950578: rss_stat: mm_id=2213312838 curr=0 type=MM_ANONPAGES size=8192B
| bash-1108 [000] d..31 73.951222: irq_disable: caller=flush_tlb_mm_range+0x115/0x130 parent=ptep_clear_flush+0x42/0x50
| bash-1108 [000] d..31 73.951222: tlb_flush: pages:1 reason:local mm shootdown (3)
The last value is the migrate-disable counter.
Things that popped up:
- trace_print_lat_context() does not print the migrate counter. Not sure
if it should. It is used in "verbose" mode and uses 8 digits and I'm
not sure ther is something processing the value.
- trace_define_common_fields() now defines a different variable. This
probably breaks things. No ide what to do in order to preserve the old
behaviour. Since this is used as a filter it should be split somehow
to be able to match both nibbles here.
Link: https://lkml.kernel.org/r/20210810132625.ylssabmsrkygokuv@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: patch description.]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ SDR: Removed change to common_preempt_count field name ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Merge tag 'printk-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek:
- Optionally, provide an index of possible printk messages via
<debugfs>/printk/index/. It can be used when monitoring important
kernel messages on a farm of various hosts. The monitor has to be
updated when some messages has changed or are not longer available by
a newly deployed kernel.
- Add printk.console_no_auto_verbose boot parameter. It allows to
generate crash dump even with slow consoles in a reasonable time
frame.
- Remove printk_safe buffers. The messages are always stored directly
to the main logbuffer, even in NMI or recursive context. Also it
allows to serialize syslog operations by a mutex instead of a spin
lock.
- Misc clean up and build fixes.
* tag 'printk-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk/index: Fix -Wunused-function warning
lib/nmi_backtrace: Serialize even messages about idle CPUs
printk: Add printk.console_no_auto_verbose boot parameter
printk: Remove console_silent()
lib/test_scanf: Handle n_bits == 0 in random tests
printk: syslog: close window between wait and read
printk: convert @syslog_lock to mutex
printk: remove NMI tracking
printk: remove safe buffers
printk: track/limit recursion
lib/nmi_backtrace: explicitly serialize banner and regs
printk: Move the printk() kerneldoc comment to its new home
printk/index: Fix warning about missing prototypes
MIPS/asm/printk: Fix build failure caused by printk
printk: index: Add indexing support to dev_printk
printk: Userspace format indexing support
printk: Rework parse_prefix into printk_parse_prefix
printk: Straighten out log_flags into printk_info_flags
string_helpers: Escape double quotes in escape_special
printk/console: Check consistent sequence number when handling race in console_unlock()
A new dynamic event is introduced: event probe. The event is attached
to an existing tracepoint and uses its fields as arguments. The user
can specify custom format string of the new event, select what tracepoint
arguments will be printed and how to print them.
An event probe is created by writing configuration string in
'dynamic_events' ftrace file:
e[:[SNAME/]ENAME] SYSTEM/EVENT [FETCHARGS] - Set an event probe
-:SNAME/ENAME - Delete an event probe
Where:
SNAME - System name, if omitted 'eprobes' is used.
ENAME - Name of the new event in SNAME, if omitted the SYSTEM_EVENT is used.
SYSTEM - Name of the system, where the tracepoint is defined, mandatory.
EVENT - Name of the tracepoint event in SYSTEM, mandatory.
FETCHARGS - Arguments:
<name>=$<field>[:TYPE] - Fetch given filed of the tracepoint and print
it as given TYPE with given name. Supported
types are:
(u8/u16/u32/u64/s8/s16/s32/s64), basic type
(x8/x16/x32/x64), hexadecimal types
"string", "ustring" and bitfield.
Example, attach an event probe on openat system call and print name of the
file that will be opened:
echo "e:esys/eopen syscalls/sys_enter_openat file=\$filename:string" >> dynamic_events
A new dynamic event is created in events/esys/eopen/ directory. It
can be deleted with:
echo "-:esys/eopen" >> dynamic_events
Filters, triggers and histograms can be attached to the new event, it can
be matched in synthetic events. There is one limitation - an event probe
can not be attached to kprobe, uprobe or another event probe.
Link: https://lkml.kernel.org/r/20210812145805.2292326-1-tz.stoyanov@gmail.com
Link: https://lkml.kernel.org/r/20210819152825.142428383@goodmis.org
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Co-developed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
As dynamic events are not created by modules, if something is attached to
one, calling "try_module_get()" on its "mod" field, is not going to keep
the dynamic event from going away.
Since dynamic events do not need the "mod" pointer of the event structure,
make a union out of it in order to save memory (there's one structure for
each of the thousand+ events in the kernel), and have any event with the
DYNAMIC flag set to use a ref counter instead.
Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/
Link: https://lkml.kernel.org/r/20210817035027.174869074@goodmis.org
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Update both the tracefs README file as well as the histogram.rst to
include an explanation of what the buckets modifier is and how to use it.
Include an example with the wakeup_latency example for both log2 and the
buckets modifiers as there was no existing log2 example.
Link: https://lkml.kernel.org/r/20210707213922.167218794@goodmis.org
Acked-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The event filters are not applied on all of the output, which results in
the flood of printk when using tp_printk. Unfolding
event_trigger_unlock_commit_regs() into trace_event_buffer_commit(), so
the filters can be applied on every output.
Link: https://lkml.kernel.org/r/20210814034538.8428-1-kernelfans@gmail.com
Cc: stable@vger.kernel.org
Fixes: 0daa230296 ("tracing: Add tp_printk cmdline to have tracepoints go to printk()")
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The event_trace_add_tracer() can fail. In this case, it leads to a crash
in start_creating with below call stack. Handle the error scenario
properly in trace_array_create_dir.
Call trace:
down_write+0x7c/0x204
start_creating.25017+0x6c/0x194
tracefs_create_file+0xc4/0x2b4
init_tracer_tracefs+0x5c/0x940
trace_array_create_dir+0x58/0xb4
trace_array_create+0x1bc/0x2b8
trace_array_get_by_name+0xdc/0x18c
Link: https://lkml.kernel.org/r/1627651386-21315-1-git-send-email-kamaagra@codeaurora.org
Cc: stable@vger.kernel.org
Fixes: 4114fbfd02 ("tracing: Enable creating new instance early boot")
Signed-off-by: Kamal Agrawal <kamaagra@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
All NMI contexts are handled the same as the safe context: store the
message and defer printing. There is no need to have special NMI
context tracking for this. Using in_nmi() is enough.
There are several parts of the kernel that are manually calling into
the printk NMI context tracking in order to cause general printk
deferred printing:
arch/arm/kernel/smp.c
arch/powerpc/kexec/crash.c
kernel/trace/trace.c
For arm/kernel/smp.c and powerpc/kexec/crash.c, provide a new
function pair printk_deferred_enter/exit that explicitly achieves the
same objective.
For ftrace, remove the printk context manipulation completely. It was
added in commit 03fc7f9c99 ("printk/nmi: Prevent deadlock when
accessing the main log buffer in NMI"). The purpose was to enforce
storing messages directly into the ring buffer even in NMI context.
It really should have only modified the behavior in NMI context.
There is no need for a special behavior any longer. All messages are
always stored directly now. The console deferring is handled
transparently in vprintk().
Signed-off-by: John Ogness <john.ogness@linutronix.de>
[pmladek@suse.com: Remove special handling in ftrace.c completely.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210715193359.25946-5-john.ogness@linutronix.de
Currently the histogram logic allows the user to write "cpu" in as an
event field, and it will record the CPU that the event happened on.
The problem with this is that there's a lot of events that have "cpu"
as a real field, and using "cpu" as the CPU it ran on, makes it
impossible to run histograms on the "cpu" field of events.
For example, if I want to have a histogram on the count of the
workqueue_queue_work event on its cpu field, running:
># echo 'hist:keys=cpu' > events/workqueue/workqueue_queue_work/trigger
Gives a misleading and wrong result.
Change the command to "common_cpu" as no event should have "common_*"
fields as that's a reserved name for fields used by all events. And
this makes sense here as common_cpu would be a field used by all events.
Now we can even do:
># echo 'hist:keys=common_cpu,cpu if cpu < 100' > events/workqueue/workqueue_queue_work/trigger
># cat events/workqueue/workqueue_queue_work/hist
# event histogram
#
# trigger info: hist:keys=common_cpu,cpu:vals=hitcount:sort=hitcount:size=2048 if cpu < 100 [active]
#
{ common_cpu: 0, cpu: 2 } hitcount: 1
{ common_cpu: 0, cpu: 4 } hitcount: 1
{ common_cpu: 7, cpu: 7 } hitcount: 1
{ common_cpu: 0, cpu: 7 } hitcount: 1
{ common_cpu: 0, cpu: 1 } hitcount: 1
{ common_cpu: 0, cpu: 6 } hitcount: 2
{ common_cpu: 0, cpu: 5 } hitcount: 2
{ common_cpu: 1, cpu: 1 } hitcount: 4
{ common_cpu: 6, cpu: 6 } hitcount: 4
{ common_cpu: 5, cpu: 5 } hitcount: 14
{ common_cpu: 4, cpu: 4 } hitcount: 26
{ common_cpu: 0, cpu: 0 } hitcount: 39
{ common_cpu: 2, cpu: 2 } hitcount: 184
Now for backward compatibility, I added a trick. If "cpu" is used, and
the field is not found, it will fall back to "common_cpu" and work as
it did before. This way, it will still work for old programs that use
"cpu" to get the actual CPU, but if the event has a "cpu" as a field, it
will get that event's "cpu" field, which is probably what it wants
anyway.
I updated the tracefs/README to include documentation about both the
common_timestamp and the common_cpu. This way, if that text is present in
the README, then an application can know that common_cpu is supported over
just plain "cpu".
Link: https://lkml.kernel.org/r/20210721110053.26b4f641@oasis.local.home
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: 8b7622bf94 ("tracing: Add cpu field for hist triggers")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
- Added option for per CPU threads to the hwlat tracer
- Have hwlat tracer handle hotplug CPUs
- New tracer: osnoise, that detects latency caused by interrupts, softirqs
and scheduling of other tasks.
- Added timerlat tracer that creates a thread and measures in detail what
sources of latency it has for wake ups.
- Removed the "success" field of the sched_wakeup trace event.
This has been hardcoded as "1" since 2015, no tooling should be looking
at it now. If one exists, we can revert this commit, fix that tool and
try to remove it again in the future.
- tgid mapping fixed to handle more than PID_MAX_DEFAULT pids/tgids.
- New boot command line option "tp_printk_stop", as tp_printk causes trace
events to write to console. When user space starts, this can easily live
lock the system. Having a boot option to stop just after boot up is
useful to prevent that from happening.
- Have ftrace_dump_on_oops boot command line option take numbers that match
the numbers shown in /proc/sys/kernel/ftrace_dump_on_oops.
- Bootconfig clean ups, fixes and enhancements.
- New ktest script that tests bootconfig options.
- Add tracepoint_probe_register_may_exist() to register a tracepoint
without triggering a WARN*() if it already exists. BPF has a path from
user space that can do this. All other paths are considered a bug.
- Small clean ups and fixes
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Merge tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- Added option for per CPU threads to the hwlat tracer
- Have hwlat tracer handle hotplug CPUs
- New tracer: osnoise, that detects latency caused by interrupts,
softirqs and scheduling of other tasks.
- Added timerlat tracer that creates a thread and measures in detail
what sources of latency it has for wake ups.
- Removed the "success" field of the sched_wakeup trace event. This has
been hardcoded as "1" since 2015, no tooling should be looking at it
now. If one exists, we can revert this commit, fix that tool and try
to remove it again in the future.
- tgid mapping fixed to handle more than PID_MAX_DEFAULT pids/tgids.
- New boot command line option "tp_printk_stop", as tp_printk causes
trace events to write to console. When user space starts, this can
easily live lock the system. Having a boot option to stop just after
boot up is useful to prevent that from happening.
- Have ftrace_dump_on_oops boot command line option take numbers that
match the numbers shown in /proc/sys/kernel/ftrace_dump_on_oops.
- Bootconfig clean ups, fixes and enhancements.
- New ktest script that tests bootconfig options.
- Add tracepoint_probe_register_may_exist() to register a tracepoint
without triggering a WARN*() if it already exists. BPF has a path
from user space that can do this. All other paths are considered a
bug.
- Small clean ups and fixes
* tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (49 commits)
tracing: Resize tgid_map to pid_max, not PID_MAX_DEFAULT
tracing: Simplify & fix saved_tgids logic
treewide: Add missing semicolons to __assign_str uses
tracing: Change variable type as bool for clean-up
trace/timerlat: Fix indentation on timerlat_main()
trace/osnoise: Make 'noise' variable s64 in run_osnoise()
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
tracing: Fix spelling in osnoise tracer "interferences" -> "interference"
Documentation: Fix a typo on trace/osnoise-tracer
trace/osnoise: Fix return value on osnoise_init_hotplug_support
trace/osnoise: Make interval u64 on osnoise_main
trace/osnoise: Fix 'no previous prototype' warnings
tracing: Have osnoise_main() add a quiescent state for task rcu
seq_buf: Make trace_seq_putmem_hex() support data longer than 8
seq_buf: Fix overflow in seq_buf_putmem_hex()
trace/osnoise: Support hotplug operations
trace/hwlat: Support hotplug operations
trace/hwlat: Protect kdata->kthread with get/put_online_cpus
trace: Add timerlat tracer
trace: Add osnoise tracer
...
Currently tgid_map is sized at PID_MAX_DEFAULT entries, which means that
on systems where pid_max is configured higher than PID_MAX_DEFAULT the
ftrace record-tgid option doesn't work so well. Any tasks with PIDs
higher than PID_MAX_DEFAULT are simply not recorded in tgid_map, and
don't show up in the saved_tgids file.
In particular since systemd v243 & above configure pid_max to its
highest possible 1<<22 value by default on 64 bit systems this renders
the record-tgids option of little use.
Increase the size of tgid_map to the configured pid_max instead,
allowing it to cover the full range of PIDs up to the maximum value of
PID_MAX_LIMIT if the system is configured that way.
On 64 bit systems with pid_max == PID_MAX_LIMIT this will increase the
size of tgid_map from 256KiB to 16MiB. Whilst this 64x increase in
memory overhead sounds significant 64 bit systems are presumably best
placed to accommodate it, and since tgid_map is only allocated when the
record-tgid option is actually used presumably the user would rather it
spends sufficient memory to actually record the tgids they expect.
The size of tgid_map could also increase for CONFIG_BASE_SMALL=y
configurations, but these seem unlikely to be systems upon which people
are both configuring a large pid_max and running ftrace with record-tgid
anyway.
Of note is that we only allocate tgid_map once, the first time that the
record-tgid option is enabled. Therefore its size is only set once, to
the value of pid_max at the time the record-tgid option is first
enabled. If a user increases pid_max after that point, the saved_tgids
file will not contain entries for any tasks with pids beyond the earlier
value of pid_max.
Link: https://lkml.kernel.org/r/20210701172407.889626-2-paulburton@google.com
Fixes: d914ba37d7 ("tracing: Add support for recording tgid of tasks")
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Paul Burton <paulburton@google.com>
[ Fixed comment coding style ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out panic and
oops helpers.
There are several purposes of doing this:
- dropping dependency in bug.h
- dropping a loop by moving out panic_notifier.h
- unload kernel.h from something which has its own domain
At the same time convert users tree-wide to use new headers, although for
the time being include new header back to kernel.h to avoid twisted
indirected includes for existing users.
[akpm@linux-foundation.org: thread_info.h needs limits.h]
[andriy.shevchenko@linux.intel.com: ia64 fix]
Link: https://lkml.kernel.org/r/20210520130557.55277-1-andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20210511074137.33666-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Co-developed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tgid_map array records a mapping from pid to tgid, where the index
of an entry within the array is the pid & the value stored at that index
is the tgid.
The saved_tgids_next() function iterates over pointers into the tgid_map
array & dereferences the pointers which results in the tgid, but then it
passes that dereferenced value to trace_find_tgid() which treats it as a
pid & does a further lookup within the tgid_map array. It seems likely
that the intent here was to skip over entries in tgid_map for which the
recorded tgid is zero, but instead we end up skipping over entries for
which the thread group leader hasn't yet had its own tgid recorded in
tgid_map.
A minimal fix would be to remove the call to trace_find_tgid, turning:
if (trace_find_tgid(*ptr))
into:
if (*ptr)
..but it seems like this logic can be much simpler if we simply let
seq_read() iterate over the whole tgid_map array & filter out empty
entries by returning SEQ_SKIP from saved_tgids_show(). Here we take that
approach, removing the incorrect logic here entirely.
Link: https://lkml.kernel.org/r/20210630003406.4013668-1-paulburton@google.com
Fixes: d914ba37d7 ("tracing: Add support for recording tgid of tasks")
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Paul Burton <paulburton@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
With the coming addition of the osnoise tracer, the configs needed to
include the latency_fsnotify() has become more complex, and to keep the
declaration in the header file the same as in the C file, just have the
logic needed to define it in one place, and that defines LATENCY_FS_NOTIFY
which will be used in the C code.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The hwlat detector and (in preparation for) the osnoise/timerlat tracers
have a set of u64 parameters that the user can read/write via tracefs.
For instance, we have hwlat_detector's window and width.
To reduce the code duplication, hwlat's window and width share the same
read function. However, they do not share the write functions because
they do different parameter checks. For instance, the width needs to
be smaller than the window, while the window needs to be larger
than the window. The same pattern repeats on osnoise/timerlat, and
a large portion of the code was devoted to the write function.
Despite having different checks, the write functions have the same
structure:
read a user-space buffer
take the lock that protects the value
check for minimum and maximum acceptable values
save the value
release the lock
return success or error
To reduce the code duplication also in the write functions, this patch
provides a generic read and write implementation for u64 values that
need to be within some minimum and/or maximum parameters, while
(potentially) being protected by a lock.
To use this interface, the structure trace_min_max_param needs to be
filled:
struct trace_min_max_param {
struct mutex *lock;
u64 *val;
u64 *min;
u64 *max;
};
The desired value is stored on the variable pointed by *val. If *min
points to a minimum acceptable value, it will be checked during the
write operation. Likewise, if *max points to a maximum allowable value,
it will be checked during the write operation. Finally, if *lock points
to a mutex, it will be taken at the beginning of the operation and
released at the end.
The definition of a trace_min_max_param needs to passed as the
(private) *data for tracefs_create_file(), and the trace_min_max_fops
(added by this patch) as the *fops file_operations.
Link: https://lkml.kernel.org/r/3e35760a7c8b5c55f16ae5ad5fc54a0e71cbe647.1624372313.git.bristot@redhat.com
Cc: Phil Auld <pauld@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Kate Carcia <kcarcia@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Clark Willaims <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
A while ago, when the "trace" file was opened, tracing was stopped, and
code was added to stop recording the comms to saved_cmdlines, for mapping
of the pids to the task name.
Code has been added that only records the comm if a trace event occurred,
and there's no reason to not trace it if the trace file is opened.
Cc: stable@vger.kernel.org
Fixes: 7ffbd48d5c ("tracing: Cache comms only after an event occurred")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The saved_cmdlines is used to map pids to the task name, such that the
output of the tracing does not just show pids, but also gives a human
readable name for the task.
If the name is not mapped, the output looks like this:
<...>-1316 [005] ...2 132.044039: ...
Instead of this:
gnome-shell-1316 [005] ...2 132.044039: ...
The names are updated when tracing is running, but are skipped if tracing
is stopped. Unfortunately, this stops the recording of the names if the
top level tracer is stopped, and not if there's other tracers active.
The recording of a name only happens when a new event is written into a
ring buffer, so there is no need to test if tracing is on or not. If
tracing is off, then no event is written and no need to test if tracing is
off or not.
Remove the check, as it hides the names of tasks for events in the
instance buffers.
Cc: stable@vger.kernel.org
Fixes: 7ffbd48d5c ("tracing: Cache comms only after an event occurred")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The kernel parameter for ftrace_dump_on_oops can take a single assignment.
That is, it can be:
ftrace_dump_on_oops or ftrace_dump_on_oops=orig_cpu
But the content in the sysctl file is a number.
0 for disabled
1 for ftrace_dump_on_oops (all CPUs)
2 for ftrace_dump_on_oops (orig CPU)
Allow the kernel command line to take a number as well to match the sysctl
numbers.
That is:
ftrace_dump_on_oops=1 is the same as ftrace_dump_on_oops
and
ftrace_dump_on_oops=2 is the same as ftrace_dump_on_oops=orig_cpu
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add a kernel command line option that disables printing of events to
console at late_initcall_sync(). This is useful when needing to see
specific events written to console on boot up, but not wanting it when
user space starts, as user space may make the console so noisy that the
system becomes inoperable.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When filtering is enabled, the event is copied into a temp buffer instead
of being written into the ring buffer directly, because the discarding of
events from the ring buffer is very expensive, and doing the extra copy is
much faster than having to discard most of the time.
As that logic is subtle, add comments to explain in more detail to what is
going on and how it works.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When filtering trace events, a temp buffer is used because the extra copy
from the temp buffer into the ring buffer is still faster than the direct
write into the ring buffer followed by a discard if the filter does not
match.
But the data that can be stored in the temp buffer is a PAGE_SIZE minus the
ring buffer event header. The calculation of that header size is complex,
but using the helper macro "struct_size()" can simplify it.
Link: https://lore.kernel.org/stable/CAHk-=whKbJkuVmzb0hD3N6q7veprUrSpiBHRxVY=AffWZPtxmg@mail.gmail.com/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The variable ret is being initialized with a value that is never read,
it is being updated later on. The assignment is redundant and can be
removed.
Link: https://lkml.kernel.org/r/20210513115517.58178-1-colin.king@canonical.com
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
If a trace event uses the %*.s notation, the trace_check_vprintf() will
fail and will warn about a bad processing of strings, because it does not
take into account the length field when processing the star (*) part.
Have it handle this case as well.
Link: https://lore.kernel.org/linux-nfs/238C0E2D-C2A4-4578-ADD2-C565B3B99842@oracle.com/
Reported-by: Chuck Lever III <chuck.lever@oracle.com>
Fixes: 9a6944fee6 ("tracing: Add a verifier to check string pointers for trace events")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
New feature:
The "func-no-repeats" option in tracefs/options directory. When set
the function tracer will detect if the current function being traced
is the same as the previous one, and instead of recording it, it will
keep track of the number of times that the function is repeated in a row.
And when another function is recorded, it will write a new event that
shows the function that repeated, the number of times it repeated and
the time stamp of when the last repeated function occurred.
Enhancements:
In order to implement the above "func-no-repeats" option, the ring
buffer timestamp can now give the accurate timestamp of the event
as it is being recorded, instead of having to record an absolute
timestamp for all events. This helps the histogram code which no longer
needs to waste ring buffer space.
New validation logic to make sure all trace events that access
dereferenced pointers do so in a safe way, and will warn otherwise.
Fixes:
No longer limit the PIDs of tasks that are recorded for "saved_cmdlines"
to PID_MAX_DEFAULT (32768), as systemd now allows for a much larger
range. This caused the mapping of PIDs to the task names to be dropped
for all tasks with a PID greater than 32768.
Change trace_clock_global() to never block. This caused a deadlock.
Clean ups:
Typos, prototype fixes, and removing of duplicate or unused code.
Better management of ftrace_page allocations.
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Merge tag 'trace-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"New feature:
- A new "func-no-repeats" option in tracefs/options directory.
When set the function tracer will detect if the current function
being traced is the same as the previous one, and instead of
recording it, it will keep track of the number of times that the
function is repeated in a row. And when another function is
recorded, it will write a new event that shows the function that
repeated, the number of times it repeated and the time stamp of
when the last repeated function occurred.
Enhancements:
- In order to implement the above "func-no-repeats" option, the ring
buffer timestamp can now give the accurate timestamp of the event
as it is being recorded, instead of having to record an absolute
timestamp for all events. This helps the histogram code which no
longer needs to waste ring buffer space.
- New validation logic to make sure all trace events that access
dereferenced pointers do so in a safe way, and will warn otherwise.
Fixes:
- No longer limit the PIDs of tasks that are recorded for
"saved_cmdlines" to PID_MAX_DEFAULT (32768), as systemd now allows
for a much larger range. This caused the mapping of PIDs to the
task names to be dropped for all tasks with a PID greater than
32768.
- Change trace_clock_global() to never block. This caused a deadlock.
Clean ups:
- Typos, prototype fixes, and removing of duplicate or unused code.
- Better management of ftrace_page allocations"
* tag 'trace-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (32 commits)
tracing: Restructure trace_clock_global() to never block
tracing: Map all PIDs to command lines
ftrace: Reuse the output of the function tracer for func_repeats
tracing: Add "func_no_repeats" option for function tracing
tracing: Unify the logic for function tracing options
tracing: Add method for recording "func_repeats" events
tracing: Add "last_func_repeats" to struct trace_array
tracing: Define new ftrace event "func_repeats"
tracing: Define static void trace_print_time()
ftrace: Simplify the calculation of page number for ftrace_page->records some more
ftrace: Store the order of pages allocated in ftrace_page
tracing: Remove unused argument from "ring_buffer_time_stamp()
tracing: Remove duplicate struct declaration in trace_events.h
tracing: Update create_system_filter() kernel-doc comment
tracing: A minor cleanup for create_system_filter()
kernel: trace: Mundane typo fixes in the file trace_events_filter.c
tracing: Fix various typos in comments
scripts/recordmcount.pl: Make vim and emacs indent the same
scripts/recordmcount.pl: Make indent spacing consistent
tracing: Add a verifier to check string pointers for trace events
...
The default max PID is set by PID_MAX_DEFAULT, and the tracing
infrastructure uses this number to map PIDs to the comm names of the
tasks, such output of the trace can show names from the recorded PIDs in
the ring buffer. This mapping is also exported to user space via the
"saved_cmdlines" file in the tracefs directory.
But currently the mapping expects the PIDs to be less than
PID_MAX_DEFAULT, which is the default maximum and not the real maximum.
Recently, systemd will increases the maximum value of a PID on the system,
and when tasks are traced that have a PID higher than PID_MAX_DEFAULT, its
comm is not recorded. This leads to the entire trace to have "<...>" as
the comm name, which is pretty useless.
Instead, keep the array mapping the size of PID_MAX_DEFAULT, but instead
of just mapping the index to the comm, map a mask of the PID
(PID_MAX_DEFAULT - 1) to the comm, and find the full PID from the
map_cmdline_to_pid array (that already exists).
This bug goes back to the beginning of ftrace, but hasn't been an issue
until user space started increasing the maximum value of PIDs.
Link: https://lkml.kernel.org/r/20210427113207.3c601884@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes: bc0c38d139 ("ftrace: latency tracer infrastructure")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Core changes:
- Provide IRQF_NO_AUTOEN as a flag for request*_irq() so drivers can be
cleaned up which either use a seperate mechanism to prevent auto-enable
at request time or have a racy mechanism which disables the interrupt
right after request.
- Get rid of the last usage of irq_create_identity_mapping() and remove
the interface.
- An overhaul of tasklet_disable(). Most usage sites of tasklet_disable()
are in task context and usually in cleanup, teardown code pathes.
tasklet_disable() spinwaits for a tasklet which is currently executed.
That's not only a problem for PREEMPT_RT where this can lead to a live
lock when the disabling task preempts the softirq thread. It's also
problematic in context of virtualization when the vCPU which runs the
tasklet is scheduled out and the disabling code has to spin wait until
it's scheduled back in. Though there are a few code pathes which invoke
tasklet_disable() from non-sleepable context. For these a new disable
variant which still spinwaits is provided which allows to switch
tasklet_disable() to a sleep wait mechanism. For the atomic use cases
this does not solve the live lock issue on PREEMPT_RT. That is mitigated
by blocking on the RT specific softirq lock.
- The PREEMPT_RT specific implementation of softirq processing and
local_bh_disable/enable().
On RT enabled kernels soft interrupt processing happens always in task
context and all interrupt handlers, which are not explicitly marked to
be invoked in hard interrupt context are forced into task context as
well. This allows to protect against softirq processing with a per
CPU lock, which in turn allows to make BH disabled regions preemptible.
Most of the softirq handling code is still shared. The RT/non-RT
specific differences are addressed with a set of inline functions which
provide the context specific functionality. The local_bh_disable() /
local_bh_enable() mechanism are obviously seperate.
- The usual set of small improvements and cleanups
Driver changes:
- New drivers for Nuvoton WPCM450 and DT 79rc3243x interrupt controllers
- Extended functionality for MStar, STM32 and SC7280 irq chips
- Enhanced robustness for ARM GICv3/4.1 drivers
- The usual set of cleanups and improvements all over the place
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Merge tag 'irq-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq updates from Thomas Gleixner:
"The usual updates from the irq departement:
Core changes:
- Provide IRQF_NO_AUTOEN as a flag for request*_irq() so drivers can
be cleaned up which either use a seperate mechanism to prevent
auto-enable at request time or have a racy mechanism which disables
the interrupt right after request.
- Get rid of the last usage of irq_create_identity_mapping() and
remove the interface.
- An overhaul of tasklet_disable().
Most usage sites of tasklet_disable() are in task context and
usually in cleanup, teardown code pathes. tasklet_disable()
spinwaits for a tasklet which is currently executed. That's not
only a problem for PREEMPT_RT where this can lead to a live lock
when the disabling task preempts the softirq thread. It's also
problematic in context of virtualization when the vCPU which runs
the tasklet is scheduled out and the disabling code has to spin
wait until it's scheduled back in.
There are a few code pathes which invoke tasklet_disable() from
non-sleepable context. For these a new disable variant which still
spinwaits is provided which allows to switch tasklet_disable() to a
sleep wait mechanism. For the atomic use cases this does not solve
the live lock issue on PREEMPT_RT. That is mitigated by blocking on
the RT specific softirq lock.
- The PREEMPT_RT specific implementation of softirq processing and
local_bh_disable/enable().
On RT enabled kernels soft interrupt processing happens always in
task context and all interrupt handlers, which are not explicitly
marked to be invoked in hard interrupt context are forced into task
context as well. This allows to protect against softirq processing
with a per CPU lock, which in turn allows to make BH disabled
regions preemptible.
Most of the softirq handling code is still shared. The RT/non-RT
specific differences are addressed with a set of inline functions
which provide the context specific functionality. The
local_bh_disable() / local_bh_enable() mechanism are obviously
seperate.
- The usual set of small improvements and cleanups
Driver changes:
- New drivers for Nuvoton WPCM450 and DT 79rc3243x interrupt
controllers
- Extended functionality for MStar, STM32 and SC7280 irq chips
- Enhanced robustness for ARM GICv3/4.1 drivers
- The usual set of cleanups and improvements all over the place"
* tag 'irq-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
irqchip/xilinx: Expose Kconfig option for Zynq/ZynqMP
irqchip/gic-v3: Do not enable irqs when handling spurious interrups
dt-bindings: interrupt-controller: Add IDT 79RC3243x Interrupt Controller
irqchip: Add support for IDT 79rc3243x interrupt controller
irqdomain: Drop references to recusive irqdomain setup
irqdomain: Get rid of irq_create_strict_mappings()
irqchip/jcore-aic: Kill use of irq_create_strict_mappings()
ARM: PXA: Kill use of irq_create_strict_mappings()
irqchip/gic-v4.1: Disable vSGI upon (GIC CPUIF < v4.1) detection
irqchip/tb10x: Use 'fallthrough' to eliminate a warning
genirq: Reduce irqdebug cacheline bouncing
kernel: Initialize cpumask before parsing
irqchip/wpcm450: Drop COMPILE_TEST
irqchip/irq-mst: Support polarity configuration
irqchip: Add driver for WPCM450 interrupt controller
dt-bindings: interrupt-controller: Add nuvoton, wpcm450-aic
dt-bindings: qcom,pdc: Add compatible for sc7280
irqchip/stm32: Add usart instances exti direct event support
irqchip/gic-v3: Fix OF_BAD_ADDR error handling
irqchip/sifive-plic: Mark two global variables __ro_after_init
...
Pointers in events that are printed are unhashed if the flags allow it,
and the logic to do so is called before processing the event output from
the raw ring buffer. In most cases, this is done when a user reads one of
the trace files.
But if tp_printk is added on the kernel command line, this logic is done
for trace events when they are triggered, and their output goes out via
printk. The unhash logic (and even the validation of the output) did not
support the tp_printk output, and would crash.
Link: https://lore.kernel.org/linux-tegra/9835d9f1-8d3a-3440-c53f-516c2606ad07@nvidia.com/
Fixes: efbbdaa22b ("tracing: Show real address for trace event arguments")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This patch only provides the implementation of the method.
Later we will used it in a combination with a new option for
function tracing.
Link: https://lkml.kernel.org/r/20210415181854.147448-5-y.karadz@gmail.com
Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The field is used to keep track of the consecutive (on the same CPU) calls
of a single function. This information is needed in order to consolidate
the function tracing record in the cases when a single function is called
number of times.
Link: https://lkml.kernel.org/r/20210415181854.147448-4-y.karadz@gmail.com
Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Linus Torvalds