The enabled_functions is used to help debug the dynamic function tracing.
Adding what trampolines are attached to files is useful for debugging.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Function graph tracing is a bit different than the function tracers, as
it is processed after either the ftrace_caller or ftrace_regs_caller
and we only have one place to modify the jump to ftrace_graph_caller,
the jump needs to happen after the restore of registeres.
The function graph tracer is dependent on the function tracer, where
even if the function graph tracing is going on by itself, the save and
restore of registers is still done for function tracing regardless of
if function tracing is happening, before it calls the function graph
code.
If there's no function tracing happening, it is possible to just call
the function graph tracer directly, and avoid the wasted effort to save
and restore regs for function tracing.
This requires adding new flags to the dyn_ftrace records:
FTRACE_FL_TRAMP
FTRACE_FL_TRAMP_EN
The first is set if the count for the record is one, and the ftrace_ops
associated to that record has its own trampoline. That way the mcount code
can call that trampoline directly.
In the future, trampolines can be added to arbitrary ftrace_ops, where you
can have two or more ftrace_ops registered to ftrace (like kprobes and perf)
and if they are not tracing the same functions, then instead of doing a
loop to check all registered ftrace_ops against their hashes, just call the
ftrace_ops trampoline directly, which would call the registered ftrace_ops
function directly.
Without this patch perf showed:
0.05% hackbench [kernel.kallsyms] [k] ftrace_caller
0.05% hackbench [kernel.kallsyms] [k] arch_local_irq_save
0.05% hackbench [kernel.kallsyms] [k] native_sched_clock
0.04% hackbench [kernel.kallsyms] [k] __buffer_unlock_commit
0.04% hackbench [kernel.kallsyms] [k] preempt_trace
0.04% hackbench [kernel.kallsyms] [k] prepare_ftrace_return
0.04% hackbench [kernel.kallsyms] [k] __this_cpu_preempt_check
0.04% hackbench [kernel.kallsyms] [k] ftrace_graph_caller
See that the ftrace_caller took up more time than the ftrace_graph_caller
did.
With this patch:
0.05% hackbench [kernel.kallsyms] [k] __buffer_unlock_commit
0.04% hackbench [kernel.kallsyms] [k] call_filter_check_discard
0.04% hackbench [kernel.kallsyms] [k] ftrace_graph_caller
0.04% hackbench [kernel.kallsyms] [k] sched_clock
The ftrace_caller is no where to be found and ftrace_graph_caller still
takes up the same percentage.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The ftrace dynamic record has a flags element that also has a counter.
Instead of hard coding "rec->flags & ~FTRACE_FL_MASK" all over the
place. Use a macro instead.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When registering a function callback for the function tracer, the ops
can specify if it wants to save full regs (like an interrupt would)
for each function that it traces, or if it does not care about regs
and just wants to have the fastest return possible.
Once a ops has registered a function, if other ops register that
function they all will receive the regs too. That's because it does
the work once, it does it for everyone.
Now if the ops wanting regs unregisters the function so that there's
only ops left that do not care about regs, those ops will still
continue getting regs and going through the work for it on that
function. This is because the disabling of the rec counter only
sees the ops registered, and does not see the ops that are still
attached, and does not know if the current ops that are still attached
want regs or not. To play it safe, it just keeps regs being processed
until no function is registered anymore.
Instead of doing that, check the ops that are still registered for that
function and if none want regs for it anymore, then disable the
processing of regs.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
if "possible cpus" is greater than actual CPUs (including offline CPUs).
Namhyung Kim did some reviews of the patches I sent this merge window and
found a memory leak and had a few clean ups.
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Merge tag 'trace-3.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing cleanups and bugfixes from Steven Rostedt:
"One bug fix that goes back to 3.10. Accessing a non existent buffer
if "possible cpus" is greater than actual CPUs (including offline
CPUs).
Namhyung Kim did some reviews of the patches I sent this merge window
and found a memory leak and had a few clean ups"
* tag 'trace-3.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix check of ftrace_trace_arrays list_empty() check
tracing: Fix leak of per cpu max data in instances
tracing: Cleanup saved_cmdlines_size changes
ring-buffer: Check if buffer exists before polling
Pull more perf updates from Ingo Molnar:
"A second round of perf updates:
- wide reaching kprobes sanitization and robustization, with the hope
of fixing all 'probe this function crashes the kernel' bugs, by
Masami Hiramatsu.
- uprobes updates from Oleg Nesterov: tmpfs support, corner case
fixes and robustization work.
- perf tooling updates and fixes from Jiri Olsa, Namhyung Ki, Arnaldo
et al:
* Add support to accumulate hist periods (Namhyung Kim)
* various fixes, refactorings and enhancements"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
perf: Differentiate exec() and non-exec() comm events
perf: Fix perf_event_comm() vs. exec() assumption
uprobes/x86: Rename arch_uprobe->def to ->defparam, minor comment updates
perf/documentation: Add description for conditional branch filter
perf/x86: Add conditional branch filtering support
perf/tool: Add conditional branch filter 'cond' to perf record
perf: Add new conditional branch filter 'PERF_SAMPLE_BRANCH_COND'
uprobes: Teach copy_insn() to support tmpfs
uprobes: Shift ->readpage check from __copy_insn() to uprobe_register()
perf/x86: Use common PMU interrupt disabled code
perf/ARM: Use common PMU interrupt disabled code
perf: Disable sampled events if no PMU interrupt
perf: Fix use after free in perf_remove_from_context()
perf tools: Fix 'make help' message error
perf record: Fix poll return value propagation
perf tools: Move elide bool into perf_hpp_fmt struct
perf tools: Remove elide setup for SORT_MODE__MEMORY mode
perf tools: Fix "==" into "=" in ui_browser__warning assignment
perf tools: Allow overriding sysfs and proc finding with env var
perf tools: Consider header files outside perf directory in tags target
...
The check that tests if ftrace_trace_arrays is empty in
top_trace_array(), uses the .prev pointer:
if (list_empty(ftrace_trace_arrays.prev))
instead of testing the variable itself:
if (list_empty(&ftrace_trace_arrays))
Although it is technically correct, it is awkward and confusing.
Use the proper method.
Link: http://lkml.kernel.org/r/87oay1bas8.fsf@sejong.aot.lge.com
Reported-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The freeing of an instance, if max data is configured, there will be
per cpu data structures created. But these are not freed when the instance
is deleted, which causes a memory leak.
A new helper function is added that frees the individual buffers within a
trace array, instead of duplicating the code. This way changes made for one
are applied to the other (normal buffer vs max buffer).
Link: http://lkml.kernel.org/r/87k38pbake.fsf@sejong.aot.lge.com
Reported-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The recent addition of saved_cmdlines_size file had some remaining
(minor - mostly coding style) issues. Fix them by passing pointer
name to sizeof() and using scnprintf().
Link: http://lkml.kernel.org/p/1402384295-23680-1-git-send-email-namhyung@kernel.org
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The per_cpu buffers are created one per possible CPU. But these do
not mean that those CPUs are online, nor do they even exist.
With the addition of the ring buffer polling, it assumes that the
caller polls on an existing buffer. But this is not the case if
the user reads trace_pipe from a CPU that does not exist, and this
causes the kernel to crash.
Simple fix is to check the cpu against buffer bitmask against to see
if the buffer was allocated or not and return -ENODEV if it is
not.
More updates were done to pass the -ENODEV back up to userspace.
Link: http://lkml.kernel.org/r/5393DB61.6060707@oracle.com
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
to help out the rest of the kernel to ease their use of trace events.
The big change for this release is the allowing of other tracers,
such as the latency tracers, to be used in the trace instances and allow
for function or function graph tracing to be in the top level
simultaneously.
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Merge tag 'trace-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"Lots of tweaks, small fixes, optimizations, and some helper functions
to help out the rest of the kernel to ease their use of trace events.
The big change for this release is the allowing of other tracers, such
as the latency tracers, to be used in the trace instances and allow
for function or function graph tracing to be in the top level
simultaneously"
* tag 'trace-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits)
tracing: Fix memory leak on instance deletion
tracing: Fix leak of ring buffer data when new instances creation fails
tracing/kprobes: Avoid self tests if tracing is disabled on boot up
tracing: Return error if ftrace_trace_arrays list is empty
tracing: Only calculate stats of tracepoint benchmarks for 2^32 times
tracing: Convert stddev into u64 in tracepoint benchmark
tracing: Introduce saved_cmdlines_size file
tracing: Add __get_dynamic_array_len() macro for trace events
tracing: Remove unused variable in trace_benchmark
tracing: Eliminate double free on failure of allocation on boot up
ftrace/x86: Call text_ip_addr() instead of the duplicated code
tracing: Print max callstack on stacktrace bug
tracing: Move locking of trace_cmdline_lock into start/stop seq calls
tracing: Try again for saved cmdline if failed due to locking
tracing: Have saved_cmdlines use the seq_read infrastructure
tracing: Add tracepoint benchmark tracepoint
tracing: Print nasty banner when trace_printk() is in use
tracing: Add funcgraph_tail option to print function name after closing braces
tracing: Eliminate duplicate TRACE_GRAPH_PRINT_xx defines
tracing: Add __bitmask() macro to trace events to cpumasks and other bitmasks
...
When an instance is created, it also gets a snapshot ring buffer
allocated (with minimum of pages). But when it is deleted the snapshot
buffer is not. There was a helper function added to match the allocation
of these ring buffers to a way to free them, but it wasn't used by
the deletion of an instance. Using that helper function solves this
memory leak.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Yoshihiro Yunomae reported that the ring buffer data for a trace
instance does not get properly cleaned up when it fails. He proposed
a patch that manually cleaned the data up and addad a bunch of labels.
The labels are not needed because all trace array is allocated with
a kzalloc which initializes it to 0 and all kfree()s can take a NULL
pointer and will ignore it.
Adding a new helper function free_trace_buffers() that can also take
null buffers to free the buffers that were allocated by
allocate_trace_buffers().
Link: http://lkml.kernel.org/r/20140605223522.32311.31664.stgit@yunodevel
Reported-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If tracing is disabled on boot up, the kernel should not execute tracing
self tests. The kernel should check whether tracing is disabled or not
before executing any of the tracing self tests.
Link: http://lkml.kernel.org/p/20140605223520.32311.56097.stgit@yunodevel
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ftrace_trace_arrays links global_trace.list. However, global_trace
is not added to ftrace_trace_arrays if trace_alloc_buffers() failed.
As the result, ftrace_trace_arrays becomes an empty list. If
ftrace_trace_arrays is an empty list, current top_trace_array() returns
an invalid pointer. As the result, the kernel can induce memory corruption
or panic.
Current implementation does not check whether ftrace_trace_arrays is empty
list or not. So, in this patch, if ftrace_trace_arrays is empty list,
top_trace_array() returns NULL. Moreover, this patch makes all functions
calling top_trace_array() handle it appropriately.
Link: http://lkml.kernel.org/p/20140605223517.32311.99233.stgit@yunodevel
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When calculating the average and standard deviation, it is required that
the count be less than UINT_MAX, otherwise the do_div() will get
undefined results. After 2^32 counts of data, the average and standard
deviation should pretty much be set anyway.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
I've been told that do_div() expects an unsigned 64 bit number, and
is undefined if a signed is used. This gave a warning on the MIPS
build. I'm not sure if a signed 64 bit dividend is really an issue
or not, but the calculation this is used for is standard deviation,
and that isn't going to be negative. We can just convert it to
unsigned and be safe.
Reported-by: David Daney <ddaney.cavm@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Introduce saved_cmdlines_size file for changing the number of saved pid-comms.
saved_cmdlines currently stores 128 command names using SAVED_CMDLINES, but
'no-existing processes' names are often lost in saved_cmdlines when we
read the trace data. So, by introducing saved_cmdlines_size file, we can
now change the 128 command names saved to something much larger if needed.
When we write a value to saved_cmdlines_size, the number of the value will
be stored in pid-comm list:
# echo 1024 > /sys/kernel/debug/tracing/saved_cmdlines_size
Here, 1024 command names can be stored. The default number is 128 and the maximum
number is PID_MAX_DEFAULT (=32768 if CONFIG_BASE_SMALL is not set). So, if we
want to avoid losing any command names, we need to set 32768 to
saved_cmdlines_size.
We can read the maximum number of the list:
# cat /sys/kernel/debug/tracing/saved_cmdlines_size
128
Link: http://lkml.kernel.org/p/20140605012427.22115.16173.stgit@yunodevel
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Somehow this unused variable warning sneaked past my warnings check
(probably due to it depending on a new config).
kernel/trace/trace_benchmark.c: In function 'trace_do_benchmark':
kernel/trace/trace_benchmark.c:38:6: warning: unused variable 'seedsq' [-Wunused-variable]
u64 seedsq;
^
Link: http://lkml.kernel.org/r/20140604160921.4f4e69c4@canb.auug.org.au
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If allocation of the max_buffer fails on boot up, the error path will
free both per_cpu data structures from the buffers. With the new redesign
of the code, those structures are freed if allocations failed. That is,
the helper function that allocates the buffers will free the per cpu data
on failure. No need to do it again. In fact, the second free will cause
a bug as the code can not handle a double free.
Link: http://lkml.kernel.org/p/20140603042803.27308.30956.stgit@yunodevel
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
With the conversion of the saved_cmdlines output to use seq_read, there
is now a race between accessing the values of the saved_cmdlines and
the writing to them. The trace_cmdline_lock needs to be taken at
the start and stop of the seq calls.
A new __trace_find_cmdline() call is created to allow for the look up
to happen without taking the lock.
Fixes: 42584c81c5 tracing: Have saved_cmdlines use the seq_read infrastructure
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In order to prevent the saved cmdline cache from being filled when
tracing is not active, the comms are only recorded after a trace event
is recorded.
The problem is, a comm can fail to be recorded if the trace_cmdline_lock
is held. That lock is taken via a trylock to allow it to happen from
any context (including NMI). If the lock fails to be taken, the comm
is skipped. No big deal, as we will try again later.
But! Because of the code that was added to only record after an event,
we may not try again later as the recording is made as a oneshot per
event per CPU.
Only disable the recording of the comm if the comm is actually recorded.
Fixes: 7ffbd48d5c "tracing: Cache comms only after an event occurred"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Current tracing_saved_cmdlines_read() implementation is naive; It allocates
a large buffer, constructs output data to that buffer for each read
operation, and then copies a portion of the buffer to the user space
buffer. This has several issues such as slow memory allocation, high
CPU usage, and even corruption of the output data.
The seq_read infrastructure is made to handle this type of work.
By converting it to use seq_read() the code becomes smaller, simplified,
as well as correct.
Link: http://lkml.kernel.org/p/20140220084431.3839.51793.stgit@yunodevel
Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In order to help benchmark the time tracepoints take, a new config
option is added called CONFIG_TRACEPOINT_BENCHMARK. When this option
is set a tracepoint is created called "benchmark:benchmark_event".
When the tracepoint is enabled, it kicks off a kernel thread that
goes into an infinite loop (calling cond_sched() to let other tasks
run), and calls the tracepoint. Each iteration will record the time
it took to write to the tracepoint and the next iteration that
data will be passed to the tracepoint itself. That is, the tracepoint
will report the time it took to do the previous tracepoint.
The string written to the tracepoint is a static string of 128 bytes
to keep the time the same. The initial string is simply a write of
"START". The second string records the cold cache time of the first
write which is not added to the rest of the calculations.
As it is a tight loop, it benchmarks as hot cache. That's fine because
we care most about hot paths that are probably in cache already.
An example of the output:
START
first=3672 [COLD CACHED]
last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
trace_printk() is used to debug fast paths within the kernel. Places
that gets called in any context (interrupt or NMI) or thousands of
times a second. Something you do not want to do with a printk().
In order to make it completely lockless as it needs a temporary buffer
to handle some of the string formatting, a page is created per cpu for
every context (four per cpu; normal, softirq, irq, NMI).
Since trace_printk() should only be used for debugging purposes,
there's no reason to waste memory on these buffers on a production
system. That means, trace_printk() should never be used unless a
developer is debugging their kernel. There's macro magic to allocate
the buffers if trace_printk() is used anywhere in the kernel.
To help enforce that trace_printk() isn't used outside of development,
when it is used, a nasty banner is displayed on bootup (or when a module
is loaded that uses trace_printk() and the kernel core does not).
Here's the banner:
**********************************************************
** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
** **
** trace_printk() being used. Allocating extra memory. **
** **
** This means that this is a DEBUG kernel and it is **
** unsafe for produciton use. **
** **
** If you see this message and you are not debugging **
** the kernel, report this immediately to your vendor! **
** **
** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
**********************************************************
That should hopefully keep developers from trying to sneak in a
trace_printk() or two.
Link: http://lkml.kernel.org/p/20140528131440.2283213c@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In the function-graph tracer, add a funcgraph_tail option
to print the function name on all } lines, not just
functions whose first line is no longer in the trace
buffer.
If a function calls other traced functions, its total
time appears on its } line. This change allows grep
to be used to determine the function for which the
line corresponds.
Update Documentation/trace/ftrace.txt to describe
this new option.
Link: http://lkml.kernel.org/p/20140520221041.8359.6782.stgit@beardog.cce.hp.com
Signed-off-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Eliminate duplicate TRACE_GRAPH_PRINT_xx defines
in trace_functions_graph.c that are already in
trace.h.
Add TRACE_GRAPH_PRINT_IRQS to trace.h, which is
the only one that is missing.
Link: http://lkml.kernel.org/p/20140520221031.8359.24733.stgit@beardog.cce.hp.com
Signed-off-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Being able to show a cpumask of events can be useful as some events
may affect only some CPUs. There is no standard way to record the
cpumask and converting it to a string is rather expensive during
the trace as traces happen in hotpaths. It would be better to record
the raw event mask and be able to parse it at print time.
The following macros were added for use with the TRACE_EVENT() macro:
__bitmask()
__assign_bitmask()
__get_bitmask()
To test this, I added this to the sched_migrate_task event, which
looked like this:
TRACE_EVENT(sched_migrate_task,
TP_PROTO(struct task_struct *p, int dest_cpu, const struct cpumask *cpus),
TP_ARGS(p, dest_cpu, cpus),
TP_STRUCT__entry(
__array( char, comm, TASK_COMM_LEN )
__field( pid_t, pid )
__field( int, prio )
__field( int, orig_cpu )
__field( int, dest_cpu )
__bitmask( cpumask, num_possible_cpus() )
),
TP_fast_assign(
memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio;
__entry->orig_cpu = task_cpu(p);
__entry->dest_cpu = dest_cpu;
__assign_bitmask(cpumask, cpumask_bits(cpus), num_possible_cpus());
),
TP_printk("comm=%s pid=%d prio=%d orig_cpu=%d dest_cpu=%d cpumask=%s",
__entry->comm, __entry->pid, __entry->prio,
__entry->orig_cpu, __entry->dest_cpu,
__get_bitmask(cpumask))
);
With the output of:
ksmtuned-3613 [003] d..2 485.220508: sched_migrate_task: comm=ksmtuned pid=3615 prio=120 orig_cpu=3 dest_cpu=2 cpumask=00000000,0000000f
migration/1-13 [001] d..5 485.221202: sched_migrate_task: comm=ksmtuned pid=3614 prio=120 orig_cpu=1 dest_cpu=0 cpumask=00000000,0000000f
awk-3615 [002] d.H5 485.221747: sched_migrate_task: comm=rcu_preempt pid=7 prio=120 orig_cpu=0 dest_cpu=1 cpumask=00000000,000000ff
migration/2-18 [002] d..5 485.222062: sched_migrate_task: comm=ksmtuned pid=3615 prio=120 orig_cpu=2 dest_cpu=3 cpumask=00000000,0000000f
Link: http://lkml.kernel.org/r/1399377998-14870-6-git-send-email-javi.merino@arm.com
Link: http://lkml.kernel.org/r/20140506132238.22e136d1@gandalf.local.home
Suggested-by: Javi Merino <javi.merino@arm.com>
Tested-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As the decision to what needs to be done (converting a call to the
ftrace_caller to ftrace_caller_regs or to convert from ftrace_caller_regs
to ftrace_caller) can easily be determined from the rec->flags of
FTRACE_FL_REGS and FTRACE_FL_REGS_EN, there's no need to have the
ftrace_check_record() return either a UPDATE_MODIFY_CALL_REGS or a
UPDATE_MODIFY_CALL. Just he latter is enough. This added flag causes
more complexity than is required. Remove it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
With the moving of the functions that determine what the mcount call site
should be replaced with into the generic code, there is a few places
in the generic code that can use them instead of hard coding it as it
does.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Move and rename get_ftrace_addr() and get_ftrace_addr_old() to
ftrace_get_addr_new() and ftrace_get_addr_curr() respectively.
This moves these two helper functions in the generic code out from
the arch specific code, and renames them to have a better generic
name. This will allow other archs to use them as well as makes it
a bit easier to work on getting separate trampolines for different
functions.
ftrace_get_addr_new() returns the trampoline address that the mcount
call address will be converted to.
ftrace_get_addr_curr() returns the trampoline address of what the
mcount call address currently jumps to.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The ftrace_hash_empty() function is a simple test:
return !hash || !hash->count;
But gcc seems to want to make it a call. As this is in an extreme
hot path of the function tracer, there's no reason it needs to be
a call. I only wrote it to be a helper function anyway, otherwise
it would have been inlined manually.
Force gcc to inline it, as it could have also been a macro.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Back in 2011 Commit ed926f9b35 "ftrace: Use counters to enable
functions to trace" changed the way ftrace accounts for enabled
and disabled traced functions. There was a comment started as:
/*
*
*/
But never finished. Well, that's rather useless. I probably forgot
to save the file before committing it. And it passed review from all
this time.
Anyway, better late than never. I updated the comment to express what
is happening in that somewhat complex code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Commit 4104d326b6 "ftrace: Remove global function list and call
function directly" cleaned up the global_ops filtering and made
the code simpler, but it left a variable "hash_enable" that was used
to know if the hash functions should be updated or not. It was
updated if the global_ops did not override them. As the global_ops
are now no different than any other ftrace_ops, the hash always
gets updated and there's no reason to use the hash_enable boolean.
The same goes for hash_disable used in ftrace_shutdown().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Replace uses of &__get_cpu_var for address calculation with this_cpu_ptr.
Link: http://lkml.kernel.org/p/alpine.DEB.2.10.1404291415560.18364@gentwo.org
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As trace event triggers are now part of the mainline kernel, I added
my trace event trigger tests to my test suite I run on all my kernels.
Now these tests get run under different config options, and one of
those options is CONFIG_PROVE_RCU, which checks under lockdep that
the rcu locking primitives are being used correctly. This triggered
the following splat:
===============================
[ INFO: suspicious RCU usage. ]
3.15.0-rc2-test+ #11 Not tainted
-------------------------------
kernel/trace/trace_events_trigger.c:80 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
4 locks held by swapper/1/0:
#0: ((&(&j_cdbs->work)->timer)){..-...}, at: [<ffffffff8104d2cc>] call_timer_fn+0x5/0x1be
#1: (&(&pool->lock)->rlock){-.-...}, at: [<ffffffff81059856>] __queue_work+0x140/0x283
#2: (&p->pi_lock){-.-.-.}, at: [<ffffffff8106e961>] try_to_wake_up+0x2e/0x1e8
#3: (&rq->lock){-.-.-.}, at: [<ffffffff8106ead3>] try_to_wake_up+0x1a0/0x1e8
stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.15.0-rc2-test+ #11
Hardware name: /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006
0000000000000001 ffff88007e083b98 ffffffff819f53a5 0000000000000006
ffff88007b0942c0 ffff88007e083bc8 ffffffff81081307 ffff88007ad96d20
0000000000000000 ffff88007af2d840 ffff88007b2e701c ffff88007e083c18
Call Trace:
<IRQ> [<ffffffff819f53a5>] dump_stack+0x4f/0x7c
[<ffffffff81081307>] lockdep_rcu_suspicious+0x107/0x110
[<ffffffff810ee51c>] event_triggers_call+0x99/0x108
[<ffffffff810e8174>] ftrace_event_buffer_commit+0x42/0xa4
[<ffffffff8106aadc>] ftrace_raw_event_sched_wakeup_template+0x71/0x7c
[<ffffffff8106bcbf>] ttwu_do_wakeup+0x7f/0xff
[<ffffffff8106bd9b>] ttwu_do_activate.constprop.126+0x5c/0x61
[<ffffffff8106eadf>] try_to_wake_up+0x1ac/0x1e8
[<ffffffff8106eb77>] wake_up_process+0x36/0x3b
[<ffffffff810575cc>] wake_up_worker+0x24/0x26
[<ffffffff810578bc>] insert_work+0x5c/0x65
[<ffffffff81059982>] __queue_work+0x26c/0x283
[<ffffffff81059999>] ? __queue_work+0x283/0x283
[<ffffffff810599b7>] delayed_work_timer_fn+0x1e/0x20
[<ffffffff8104d3a6>] call_timer_fn+0xdf/0x1be^M
[<ffffffff8104d2cc>] ? call_timer_fn+0x5/0x1be
[<ffffffff81059999>] ? __queue_work+0x283/0x283
[<ffffffff8104d823>] run_timer_softirq+0x1a4/0x22f^M
[<ffffffff8104696d>] __do_softirq+0x17b/0x31b^M
[<ffffffff81046d03>] irq_exit+0x42/0x97
[<ffffffff81a08db6>] smp_apic_timer_interrupt+0x37/0x44
[<ffffffff81a07a2f>] apic_timer_interrupt+0x6f/0x80
<EOI> [<ffffffff8100a5d8>] ? default_idle+0x21/0x32
[<ffffffff8100a5d6>] ? default_idle+0x1f/0x32
[<ffffffff8100ac10>] arch_cpu_idle+0xf/0x11
[<ffffffff8107b3a4>] cpu_startup_entry+0x1a3/0x213
[<ffffffff8102a23c>] start_secondary+0x212/0x219
The cause is that the triggers are protected by rcu_read_lock_sched() but
the data is dereferenced with rcu_dereference() which expects it to
be protected with rcu_read_lock(). The proper reference should be
rcu_dereference_sched().
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Commit 4104d326b6 "ftrace: Remove global function list and call
function directly" cleaned up the global_ops filtering and made
the code simpler. But it left out function graph filtering which
also depended on that code. The function graph filtering still
needs to use global_ops as the filter otherwise it wont filter
at all.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
uprobe_perf_open()->uprobe_apply() can fail, but this error is wrongly
ignored. Change uprobe_perf_open() to do uprobe_perf_close() and return
the error code in this case.
Change uprobe_perf_close() to propogate the error from uprobe_apply()
as well, although it should not fail.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Preparation. Move uprobe_perf_close() up before uprobe_perf_open() to
avoid the forward declaration in the next patch and make it readable.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Now that the ring buffer has a built in way to wake up readers
when there's data, using irq_work such that it is safe to do it
in any context. But it was still using the old "poor man's"
wait polling that checks every 1/10 of a second to see if it
should wake up a waiter. This makes the latency for a wake up
excruciatingly long. No need to do that anymore.
Completely remove the different wait_poll types from the tracers
and have them all use the default one now.
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When reading from trace_pipe, if tracing is off but nothing was read
it should block. If something is read and tracing is off, then EOF
is returned. If tracing is on and there's nothing to read, it will block.
But because the check of whether tracing is off and something was read
is done after the block on the pipe, it is hit or miss if the EOF is
returned or not leading to inconsistent behavior.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
A race exists between module loading and enabling of function tracer.
CPU 1 CPU 2
----- -----
load_module()
module->state = MODULE_STATE_COMING
register_ftrace_function()
mutex_lock(&ftrace_lock);
ftrace_startup()
update_ftrace_function();
ftrace_arch_code_modify_prepare()
set_all_module_text_rw();
<enables-ftrace>
ftrace_arch_code_modify_post_process()
set_all_module_text_ro();
[ here all module text is set to RO,
including the module that is
loading!! ]
blocking_notifier_call_chain(MODULE_STATE_COMING);
ftrace_init_module()
[ tries to modify code, but it's RO, and fails!
ftrace_bug() is called]
When this race happens, ftrace_bug() will produces a nasty warning and
all of the function tracing features will be disabled until reboot.
The simple solution is to treate module load the same way the core
kernel is treated at boot. To hardcode the ftrace function modification
of converting calls to mcount into nops. This is done in init/main.c
there's no reason it could not be done in load_module(). This gives
a better control of the changes and doesn't tie the state of the
module to its notifiers as much. Ftrace is special, it needs to be
treated as such.
The reason this would work, is that the ftrace_module_init() would be
called while the module is in MODULE_STATE_UNFORMED, which is ignored
by the set_all_module_text_ro() call.
Link: http://lkml.kernel.org/r/1395637826-3312-1-git-send-email-indou.takao@jp.fujitsu.com
Reported-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@vger.kernel.org # 2.6.38+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The functions ftrace_set_global_filter() and ftrace_set_global_notrace()
still have their old names in the kernel doc (ftrace_set_filter and
ftrace_set_notrace respectively). Replace these with the real names.
Link: http://lkml.kernel.org/p/1398006644-5935-3-git-send-email-wangjiaxing@insigma.com.cn
Signed-off-by: Jiaxing Wang <wangjiaxing@insigma.com.cn>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When using ftrace_ops_list_func, we should skip 4 instead of 3,
to avoid ftrace_call+0x5/0xb appearing in the stack trace:
Depth Size Location (110 entries)
----- ---- --------
0) 2956 0 update_curr+0xe/0x1e0
1) 2956 68 ftrace_call+0x5/0xb
2) 2888 92 enqueue_entity+0x53/0xe80
3) 2796 80 enqueue_task_fair+0x47/0x7e0
4) 2716 28 enqueue_task+0x45/0x70
5) 2688 12 activate_task+0x22/0x30
Add a function using_ftrace_ops_list_func() to test for this while keeping
ftrace_ops_list_func to remain static.
Link: http://lkml.kernel.org/p/1398006644-5935-2-git-send-email-wangjiaxing@insigma.com.cn
Signed-off-by: Jiaxing Wang <wangjiaxing@insigma.com.cn>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Use NOKPROBE_SYMBOL macro to protect functions from
kprobes instead of __kprobes annotation in ftrace.
This applies nokprobe_inline annotation for some cases,
because NOKPROBE_SYMBOL() will inhibit inlining by
referring the symbol address.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140417081828.26341.55152.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no need to prohibit probing on the functions
used for preparation and uprobe only fetch functions.
Those are safely probed because those are not invoked
from kprobe's breakpoint/fault/debug handlers. So there
is no chance to cause recursive exceptions.
Following functions are now removed from the kprobes blacklist:
update_bitfield_fetch_param
free_bitfield_fetch_param
kprobe_register
FETCH_FUNC_NAME(stack, type) in trace_uprobe.c
FETCH_FUNC_NAME(memory, type) in trace_uprobe.c
FETCH_FUNC_NAME(memory, string) in trace_uprobe.c
FETCH_FUNC_NAME(memory, string_size) in trace_uprobe.c
FETCH_FUNC_NAME(file_offset, type) in trace_uprobe.c
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140417081800.26341.56504.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch adds static to the following functions:
-cycle_t buffer_ftrace_now
-void free_snapshot
-int trace_selftest_startup_dynamic_tracing
Link: http://lkml.kernel.org/p/20140417214442.d7abc7c0b0e4b90e7fedecc9@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
