Avoid modifying the mcount call-site if there is a kprobe installed on it.
These records are not marked as failed however. This allowed the filter
rules on them to remain up-to-date. Whenever the kprobe on the corresponding
record is removed, the record gets updated as normal.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Let records identified as being kprobe'd be marked as "frozen". The trouble
with records which have a kprobe installed on their mcount call-site is
that they don't get updated. So if such a function which is currently being
traced gets its tracing disabled due to a new filter rule (or because it
was added to the notrace list) then it won't be updated and continue being
traced. This patch allows scanning of all frozen records during tracing to
check if they should be traced.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Record the address of the mcount call-site. Currently all archs except sparc64
record the address of the instruction following the mcount call-site. Some
general cleanups are entailed. Storing mcount addresses in rec->ip enables
looking them up in the kprobe hash table later on to check if they're kprobe'd.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: davem@davemloft.net
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This is a fix to give notrace filter rules priority over "set_ftrace_filter"
rules.
This fix ensures that functions which are set to be filtered and are
concurrently marked as "notrace" don't get recorded. As of now, if
a record is marked as FTRACE_FL_FILTER and is enabled, then the notrace
flag is not checked. Tested on x86-32.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Do not print loglevel before "entries of %ld bytes". Move it to the previous
pr_info.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Found that inspite of setting the current_tracer to "none", trace from
the previous trace type continued to be collected. The patch below fixes
this and causes the trace to be disabled when the "none" type is
selected.
Compile and boot tested the patch for functionality.
Signed-off-by: Ankita Garg <ankita@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Steven Rostedt wrote:
> If we unload a module and reload it, will it ever get converted again?
The intent was always to filter core kernel functions to prevent their freeing.
Here's a fix which should allow re-recording of module call-sites.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Identify functions which had their mcount call-site updates failed. This can
help us track functions which ftrace shouldn't fiddle with, and are thus not
being traced. If there is no race with any external agent which is modifying
the mcount call-site, then this file displays no entries (normal case).
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Prevent freeing of records which cause problems and correspond to function from
core kernel text. A new flag, FTRACE_FL_CONVERTED is used to mark a record
as "converted". All other records are patched lazily to NOPs. Failed records
now also remain on frace_hash table. Each invocation of ftrace_record_ip now
checks whether the traced function has ever been recorded (including past
failures) and doesn't re-record it again.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In dynamic ftrace, the mcount function starts off pointing to a stub
function that just returns.
On start up, the call to the stub is modified to point to a "record_ip"
function. The job of the record_ip function is to add the function to
a pre-allocated hash list. If the function is already there, it simply is
ignored, otherwise it is added to the list.
Later, a ftraced daemon wakes up and calls kstop_machine if any functions
have been recorded, and changes the calls to the recorded functions to
a simple nop. If no functions were recorded, the daemon goes back to sleep.
The daemon wakes up once a second to see if it needs to update any newly
recorded functions into nops. Usually it does not, but if a lot of code
has been executed for the first time in the kernel, the ftraced daemon
will call kstop_machine to update those into nops.
The problem currently is that there's no way to stop the daemon from doing
this, and it can cause unneeded latencies (800us which for some is bothersome).
This patch adds a new file /debugfs/tracing/ftraced_enabled. If the daemon
is active, reading this will return "enabled\n" and "disabled\n" when the
daemon is not running. To disable the daemon, the user can echo "0" or
"disable" into this file, and "1" or "enable" to re-enable the daemon.
Since the daemon is used to convert the functions into nops to increase
the performance of the system, I also added that anytime something is
written into the ftraced_enabled file, kstop_machine will run if there
are new functions that have been detected that need to be converted.
This way the user can disable the daemon but still be able to control the
conversion of the mcount calls to nops by simply,
"echo 0 > /debugfs/tracing/ftraced_enabled"
when they need to do more conversions.
To see the number of converted functions:
"cat /debugfs/tracing/dyn_ftrace_total_info"
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tracing functions via ftrace which have a kretprobe installed on them, can produce misleading output in their trace logs. E.g, consider the correct trace of the following sequence:
do_IRQ()
{
~
irq_enter();
~
}
Trace log (sample):
<idle>-0 [00] 4154504455.781616: irq_enter <- do_IRQ
But if irq_enter() has a kretprobe installed on it, the return value stored on the stack at each invocation is modified to divert the return to a kprobe trampoline function called kretprobe_trampoline(). So with this the trace would (currently) look like:
<idle>-0 [00] 4154504455.781616: irq_enter <- kretprobe_trampoline
Now this is quite misleading to the end user, as it suggests something that didn't actually happen. So just to avoid such misinterpretations, the inlined patch aims to output such a log as:
<idle>-0 [00] 4154504455.781616: irq_enter <- [unknown/kretprobe'd]
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Hi Ingo/Steven,
Ftrace currently maintains an update count which includes false updates,
i.e, updates which failed. If anything, such failures should be tracked
by some separate variable, but this patch provides a minimal fix.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: rostedt@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Hi Steven,
I noticed that concurrent instances of ftrace_record_ip()
have a race between ftrace_hash list traversal during
ftrace_ip_in_hash() (before acquiring ftrace_shutdown_lock)
and ftrace_add_hash(). If it's so then this should fix it.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: rostedt@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The new work with converting the trace hooks over to markers broke the
command line recording of ftrace. This patch fixes it again.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
While debugging latencies in the RT kernel, I found that it would be nice
to be able to filter away functions from the trace than just to filter
on functions.
I added a new interface to the debugfs tracing directory called
set_ftrace_notrace
When dynamic frace is enabled, this lets you filter away functions that will
not be recorded in the trace. It is similar to adding 'notrace' to those
functions but by doing it without recompiling the kernel.
Here's how set_ftrace_filter and set_ftrace_notrace interact. Remember, if
set_ftrace_filter is set, it removes all functions from the trace execpt for
those listed in the set_ftrace_filter. set_ftrace_notrace will prevent those
functions from being traced.
If you were to set one function in both set_ftrace_filter and
set_ftrace_notrace and that function was the same, then you would end up
with an empty trace.
the set of functions to trace is:
set_ftrace_filter == empty then
all functions not in set_ftrace_notrace
else
set of the set_ftrace_filter and not in set of set_ftrace_notrace.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Printing out new max latencies was fine for the old RT tracer. But for
mainline it is a bit messy. We also need to test if the run queue
is locked before we can do the print. This means that we may not be
printing out latencies if the run queue is locked on another CPU.
This produces inconsistencies in the output.
This patch simply removes the print altogether.
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>
This patch adds function tracing to the functions that are called
on the CPU of the task being traced.
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>
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>
Non-zero pid indicates the MMIO access originated in user space.
We do not catch that kind of accesses yet, so always print zero for now.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
another weekend, another patch. This should apply on top of my previous patch
from March 23rd.
Summary of changes:
- Print PCI device list in output header
- work around recursive probe hits on SMP
- refactor dis/arm_kmmio_fault_page() and add check for page levels
- remove un/reference_kmmio(), the die notifier hook is registered
permanently into the list
- explicitly check for single stepping in die notifier callback
I have tested this version on my UP Athlon64 desktop with Nouveau, and
SMP Core 2 Duo laptop with the proprietary nvidia driver. Both systems
are 64-bit. One previously unknown bug crept into daylight: the ftrace
framework's output routines print the first entry last after buffer has
wrapped around.
The most important regressions compared to non-ftrace mmiotrace at this
time are:
- failure of trace_pipe file
- illegal lines in output file
- unaware of losing data due to buffer full
Personally I'd like to see these three solved before submitting to
mainline. Other issues may come up once we know when we lose events.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
here is a patch that makes mmiotrace work almost well within the tracing
framework. The patch applies on top of my previous patch. I have my own
output formatting in place now.
Summary of changes:
- fix the NULL dereference that was due to not calling tracing_reset()
- add print_line() callback into struct tracer
- implement print_line() for mmiotrace, producing up-to-spec text
- add my output header, but that is not really called in the right place
- rewrote the main structs in mmiotrace
- added two new trace entry types: TRACE_MMIO_RW and TRACE_MMIO_MAP
- made some functions in trace.c non-static
- check current==NULL in tracing_generic_entry_update()
- fix(?) comparison in trace_seq_printf()
Things seem to work fine except a few issues. Markers (text lines injected
into mmiotrace log) are missing, I did not feel hacking them in before we
have variable length entries. My output header is printed only for 'trace'
file, but not 'trace_pipe'. For some reason, despite my quick fix,
iter->trace is NULL in print_trace_line() when called from 'trace_pipe'
file, which means I don't get proper output formatting.
I only tried by loading nouveau.ko, which just detects the card, and that
is traced fine. I didn't try further. Map, two reads and unmap. Works
perfectly.
I am missing the information about overflows, I'd prefer to have a
counter for lost events. I didn't try, but I guess currently there is no
way of knowning when it overflows?
So, not too far from being fully operational, it seems :-)
And looking at the diffstat, there also is some 700-900 lines of user space
code that just became obsolete.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
On Sat, 22 Mar 2008 13:07:47 +0100
Ingo Molnar <mingo@elte.hu> wrote:
> > > i'd suggest the following: pull x86.git and sched-devel.git into a
> > > single tree [the two will combine without rejects]. Then try to add a
> > > kernel/tracing/trace_mmiotrace.c ftrace plugin. The trace_sysprof.c
> > > plugin might be a good example.
> >
> > I did this and now I have mmiotrace enabled/disabled via the tracing
> > framework (what do we call this, since ftrace is one of the tracers?).
>
> cool! could you send the patches for that? (even if they are not fully
> functional yet)
Patch attached in the end. Nice to see how much code disappeared. I tried
to mark all the features I had to break with XXX-comments.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that ftrace is being ported to other architectures, it has become
apparent that DYNAMIC_FTRACE is dependent on whether or not that
architecture implements dynamic ftrace. FTRACE itself may be ported to
an architecture without porting dynamic ftrace.
This patch adds HAVE_DYNAMIC_FTRACE to allow architectures to port ftrace
without having to also port the dynamic aspect as well.
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 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>
David S. Miller noticed the following bug: the -pg instrumentation
function callback is named differently on each platform. On x86 it
is mcount, on sparc it is _mcount. So the export does not make sense
in kernel/trace/ftrace.c - move it to x86.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
It causes unaligned access traps on platforms like sparc
(ftrace_page may be marked packed, but once we return
a dyn_ftrace sub-object from this array to another piece
of code, the "packed" part of the typing information doesn't
propagate).
But also, it didn't serve any purpose either. Even if packed,
on 64-bit or 32-bit, it didn't give us any more dyn_ftrace
entries per-page.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Porting ftrace to the marker infrastructure.
Don't need to chain to the wakeup tracer from the sched tracer, because markers
support multiple probes connected.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently there is no protection from the root user to use up all of
memory for trace buffers. If the root user allocates too many entries,
the OOM killer might start kill off all tasks.
This patch adds an algorith to check the following condition:
pages_requested > (freeable_memory + current_trace_buffer_pages) / 4
If the above is met then the allocation fails. The above prevents more
than 1/4th of freeable memory from being used by trace buffers.
To determine the freeable_memory, I made determine_dirtyable_memory in
mm/page-writeback.c global.
Special thanks goes to Peter Zijlstra for suggesting the above calculation.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Refactor code from tracing_read_pipe() and create trace_seq_to_user().
Moved trace_seq_reset() call before iter->trace->read() call so that
when all leftover data is returned, trace_seq is reset automatically.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Due to debug hooks in the kernel that can change the way smp_processor_id
works, use raw_smp_processor_id in mcount called functions (namely
ftrace_record_ip). Currently we annotate most debug functions from calling
mcount, but we should not rely on that to prevent kernel lockups.
This patch uses the raw_smp_processor_id to prevent a recusive crash
that can happen if a debug hook in smp_processor_id calls mcount.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In resetting the iterator in read_pipe, the reset of pos was
postitioned in the wrong location with respect to the memset
operation. The current code sets pos, incorrectly, to zero.
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 method for open_pipe and open_read to the pluggins
so that they can add a header to the trace pipe call.
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 sets up the infrastructure to record overruns of the tracing
buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In cleaning up of the sched_switch code, the function trace recording
of task comms was removed. This patch adds back the recording of comms
for function trace. The output of ftrace now has the task comm instead
of <...>.
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 is first installment of adding documentation to the ftrace.
Expect many more patches of this kind in the near future.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently ftrace allocates a trace buffer for every possible CPU.
Work is being done to change it to only online CPUs and add hooks
to hotplug CPUS.
This patch lays out the infrastructure for such a change.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
