It is possible that the testing thread in the ftrace wakeup test does not
run before we stop the trace. This will cause the trace to fail since nothing
will be in the buffers.
This patch adds a small wait in the wakeup test to allow for the woken task
to run and be traced.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A no-op tracer which can serve two purposes:
1. A template for development of a new tracer.
2. A convenient way to see ftrace_printk() calls without
an irrelevant trace making the output messy.
[ mingo@elte.hu: resolved conflicts ]
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds a feature that can help kernel developers debug their
code using ftrace.
int ftrace_printk(const char *fmt, ...);
This records into the ftrace buffer using printf formatting. The entry
size in the buffers are still a fixed length. A new type has been added
that allows for more entries to be used for a single recording.
The start of the print is still the same as the other entries.
It returns the number of characters written to the ftrace buffer.
For example:
Having a module with the following code:
static int __init ftrace_print_test(void)
{
ftrace_printk("jiffies are %ld\n", jiffies);
return 0;
}
Gives me:
insmod-5441 3...1 7569us : ftrace_print_test: jiffies are 4296626666
for the latency_trace file and:
insmod-5441 [03] 1959.370498: ftrace_print_test jiffies are 4296626666
for the trace file.
Note: Only the infrastructure should go into the kernel. It is to help
facilitate debugging for other kernel developers. Calls to ftrace_printk
is not intended to be left in the kernel, and should be frowned upon just
like scattering printks around in the code.
But having this easily at your fingertips helps the debugging go faster
and bugs be solved quicker.
Maybe later on, we can hook this with markers and have their printf format
be sucked into ftrace output.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The check_pages function is called often enough that it can cause problems
with trace outputs or even bringing the system to a halt.
This patch limits the check_pages to the places that are most likely to
have problems. The check is made at the flip between the global array and
the max save array, as well as when the size of the buffers changes and
the self tests.
This patch also removes the BUG_ON from check_pages and replaces it with
a WARN_ON and disabling of the tracer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: pq@iki.fi
Cc: proski@gnu.org
Cc: sandmann@redhat.com
Cc: a.p.zijlstra@chello.nl
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
that's the only tested platform for now. If there's interest we
can make it generic easily.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch adds full support for ftrace for PowerPC (both 64 and 32 bit).
This includes dynamic tracing and function filtering.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The wakeup selftest used an internal API for setting the test task priority.
This patch fixes it to use the proper API for performing such a task.
Thanks goes to Randy Dunlap for pointing out this build failure.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
There is a slight race condition in the selftest where the max update
of the wakeup and irqs/preemption off tests can be doing a max update as
the buffers are being tested. If this happens the system can crash with
a GPF.
This patch adds the max update spinlock around the checking of the
buffers to prevent such a race.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
With the adding of the configuration changes in the Makefile to prevent
tracing of functions in the ftrace code, all tracing of all the ftrace
code has been removed. Unfortunately, one of the selftests, relied on
a function to be traced. With the new change, the function was no longer
traced and the test failed.
This patch separates out the test function into its own file so that
we can add the "-pg" flag to the compilation of that function and the
adding of the mcount call to that function.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The selftest validation code checks for valid entries in the trace buffer.
TRACE_STACK and TRACE_SPECIAL have been added to the code but not to
the validator. This patch adds the two to prevent them from flagging a
failure in the selftest.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
now that we have a kbuild method for notrace, no need to pollute the
C code with the annotations.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since ftrace touches practically every function. If we detect any
anomaly, we want to fully disable ftrace. This patch adds code
to try shutdown ftrace as much as possible without doing any more
harm is something is detected not quite correct.
This only kills ftrace, this patch does have checks for other parts of
the tracer (irqsoff, wakeup, etc.).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If the trace buffer is detected to be corrupted, then we
disable all tracers.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch adds a startup self test on dynamic code modification
and filters. The test filters on a specific function, makes sure that
no other function is traced, exectutes the function, then makes sure that
the function is traced.
This patch also fixes a slight bug with the ftrace selftest, where
tracer_enabled was not being set.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
