Impact: build fix on non-lockdep architectures

Some architectures do not support a way to read the irq flags that
is set from "local_irq_save(flags)" to determine if interrupts were
disabled or enabled. Ftrace uses this information to display to the user
if the trace occurred with interrupts enabled or disabled.

Besides the fact that those archs that do not support this will fail to
compile, unless they fix it, we do not want to have the trace simply
say interrupts were not disabled or they were enabled, without knowing
the real answer.

This patch adds a 'X' in the output to let the user know that the
architecture they are running on does not support a way for the tracer
to determine if interrupts were enabled or disabled. It also lets those
same archs compile with tracing enabled.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on non-function-tracing architectures

The trace_nop is the tracer that is defined when no tracer is set in
the ftrace infrastructure.

The trace_nop was mistakenly selected by HAVE_FTRACE due to the confusion
between ftrace infrastructure and the ftrace function tracer (which has
been solved by renaming the function tracer).

This patch changes the select to the approriate TRACING.

This patch should fix compile errors on architectures that do not define
the FUNCTION_TRACER.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: corrects a bug which made the non-dyn function tracer not functional

With latest git, the non-dynamic function tracer didn't get any trace.

The problem was the fact that ftrace_enabled wasn't initialized to 1
because ftrace hasn't any init function when DYNAMIC_FTRACE is disabled.

So when a tracer tries to register an ftrace_ops struct,
__register_ftrace_function failed to set the hook.

This patch corrects it by setting an init function to initialize
ftrace during the boot.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The commit (in linux-tip) c2931e05
 ( ftrace: return an error when setting a nonexistent tracer )
added useful code that would error when a bad tracer was written into
the current_tracer file.

But this had a bug if the amount written was more than the amount read by
that code. The first iteration would set the tracer correctly, but since
it did not consume the rest of what was written (usually whitespace), the
userspace utility would continue to write what was not consumed. This
second iteration would fail to find a tracer and return -EINVAL. Funny
thing is that the tracer would have already been set.

This patch just consumes all the data that is written to the file.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on Alpha

When tracing is enabled, some arch have included <linux/irqflags.h>
on their <asm/system.h> but others like alpha or m68k don't.

Build error on alpha:

kernel/trace/trace.c: In function 'tracing_cpumask_write':
kernel/trace/trace.c:2145: error: implicit declaration of function 'raw_local_irq_disable'
kernel/trace/trace.c:2162: error: implicit declaration of function 'raw_local_irq_enable'

Tested on Alpha through a cross-compiler (should correct a similar issue on m68k).
Reported-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix

If the boot tracer is selected but not the sched_switch,
there will be a build failure:

 kernel/built-in.o: In function `boot_trace_init':
 trace_boot.c:(.text+0x5ee38): undefined reference to `sched_switch_trace'
 kernel/built-in.o: In function `disable_boot_trace':
 (.text+0x5eee1): undefined reference to `tracing_stop_cmdline_record'
 kernel/built-in.o: In function `enable_boot_trace':
 (.text+0x5ef11): undefined reference to `tracing_start_cmdline_record'

This patch fixes it.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

A powerpc ppc64_defconfig build produces these warnings:

kernel/trace/ring_buffer.c: In function 'rb_add_time_stamp':
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 2 has type 'u64'
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 3 has type 'u64'
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 4 has type 'u64'

Just cast the u64s to unsigned long long like we do everywhere else.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

this warning:

  kernel/trace/ftrace.c:189: warning: ‘frozen_record_count’ defined but not used

triggers because frozen_record_count is only used in the KCONFIG_MARKERS
case. Move the variable it there.

Alas, this frozen-record facility seems to have little use. The
frozen_record_count variable is not used by anything, nor the flags.

So this section might need a bit of dead-code-removal care as well.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 kernel/trace/ftrace.c: In function 'ftrace_release':
 kernel/trace/ftrace.c:271: error: implicit declaration of function 'ftrace_release_hash'

release_hash is not needed without dftraced.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The ftrace hash was used by the ftrace_daemon code. The record ip function
would place the calling address (ip) into the hash. The daemon would later
read the hash and modify that code.

The hash complicates the code. This patch removes it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The arch dependent function ftrace_mcount_set was only used by the daemon
start up code. This patch removes it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The ftrace daemon is complex and error prone.  This patch strips it out
of the code.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add ftrace warn on to disable ftrace as well as report a warning.

[ Thanks to Andrew Morton for suggesting using the WARN_ON return value ]
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When an anomaly is detected, we need a way to completely disable
ftrace. Right now we have two functions: ftrace_kill and ftrace_kill_atomic.
The ftrace_kill tries to do it in a "nice" way by converting everything
back to a nop.

The "nice" way is dangerous itself, so this patch removes it and only
has the "atomic" version, which is all that is needed.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Have the ftrace_modify_code return error values:

  -EFAULT on error of reading the address

  -EINVAL if what is read does not match what it expected

  -EPERM  if the write fails to update after a successful match.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The pages of a buffer was originally pointing to the page struct, it
now points to the page address. The freeing of the page still uses
the page frame free "__free_page" instead of the correct free_page to
the address.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We seem to have plenty tracers, lets create a menu and not clutter
the already cluttered debug menu more.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NFrédéric Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The stack trace API does not record if the stack is not on the current
task's stack. That is, if the stack is the interrupt stack or NMI stack,
the output does not show. Also, the size of those stacks are not
consistent with the size of the thread stack, this makes the calculation
of the stack size usually bogus.

This all confuses the stack tracer. I unfortunately do not have time to
fix all these problems, but this patch does record the worst stack when
the stack pointer is on the tasks stack (instead of bogus numbers).

The patch simply returns if the stack pointer is not on the task's stack.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

To avoid further confusion between the ftrace infrastructure and the
function tracer. This patch renames the "ftrace" function tracer
to "function".

Now in available_tracers, instead of "ftrace" there will be "function".

This makes more sense, since people will not know exactly what the
"ftrace" tracer does.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Due to confusion between the ftrace infrastructure and the gcc profiling
tracer "ftrace", this patch renames the config options from FTRACE to
FUNCTION_TRACER.  The other two names that are offspring from FTRACE
DYNAMIC_FTRACE and FTRACE_MCOUNT_RECORD will stay the same.

This patch was generated mostly by script, and partially by hand.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

A lot of tracers have HAVE_FTRACE as a dependent config where it
really should not. The HAVE_FTRACE is a misnomer (soon to be fixed)
and describes if the architecture has the function tracer (mcount)
implemented. The ftrace infrastructure is implemented in all archs.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The x86 architecture uses a static recording of mcount caller locations
and is not affected by this patch.

For architectures still using the dynamic ftrace daemon, this patch is
critical. It removes the race between the recording of a function that
calls mcount, the unloading of a module, and the ftrace daemon updating
the call sites.

This patch adds the releasing of the hash functions that the daemon uses
to update the mcount call sites. When a module is unloaded, not only
are the replaced call site table update, but now so is the hash recorded
functions that the ftrace daemon will use.

Again, architectures that implement MCOUNT_RECORD are not affected by
this (which currently only x86 has).
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Improve the help text of the boot tracer.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Improve the help text that is displayed for CONFIG_STACK_TRACER.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Remove the runtime BUG_ON and change to a compile-time check in
the macro that calls the hex format routine

[Noticed by Joe Perches]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix the output of ftrace in hex mode as the hi/lo nibbles are output in
reverse order. Without this patch, the output of ftrace is:

raw mode : 6474 0 141531612444 0 140 + 6402 120 S
hex mode : 000091a4 00000000 000000023f1f50c1 00000000 c8 000000b2 00009120 87 ffff00c8 00000035

There is an inversion on ouput hex(6474) is 194a

[based on a patch by Philippe Reynes <tremyfr@yahoo.fr>]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When printing nanoseconds, the right printk format string is %09 not %06...
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Acked-by: NFrédéric Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When one try to set a nonexistent tracer, no error is returned
as if the name of the tracer was correct.
We should return -EINVAL.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Now that the ring buffer is reentrant, some of the ftrace tracers
(sched_swich, debugging traces) can also be reentrant.

Note: Never make the function tracer reentrant, that can cause
  recursion problems all over the kernel. The function tracer
  must disable reentrancy.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch replaces the local_irq_save/restore with preempt_disable/
enable. This allows for interrupts to enter while recording.
To write to the ring buffer, you must reserve data, and then
commit it. During this time, an interrupt may call a trace function
that will also record into the buffer before the commit is made.

The interrupt will reserve its entry after the first entry, even
though the first entry did not finish yet.

The time stamp delta of the interrupt entry will be zero, since
in the view of the trace, the interrupt happened during the
first field anyway.

Locking still takes place when the tail/write moves from one page
to the next. The reader always takes the locks.

A new page pointer is added, called the commit. The write/tail will
always point to the end of all entries. The commit field will
point to the last committed entry. Only this commit entry may
update the write time stamp.

The reader can only go up to the commit. It cannot go past it.

If a lot of interrupts come in during a commit that fills up the
buffer, and it happens to make it all the way around the buffer
back to the commit, then a warning is printed and new events will
be dropped.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Remove the global head and tail indexes and move them into the
page header. Each page will now keep track of where the last
write and read was made. We also rename the head and tail to read
and write for better clarification.

This patch is needed for future enhancements to move the ring buffer
to a lockless solution.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

At this time, only built-in initcalls interest us.
We can't really produce a relevant graph if we include
the modules initcall too.

I had good results after this patch (see svg in attachment).
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The assigning of the pc counter is in the wrong spot in the
check_critical_timing function. The pc variable is used in the
out jump.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

My original patch had a compile bug when NUMA was configured. I
referenced cpu when it should have been cpu_buffer->cpu.

Ingo quickly fixed this bug by replacing cpu with 'i' because that
was the loop counter. Unfortunately, the 'i' was the counter of
pages, not CPUs. This caused a crash when the number of pages allocated
for the buffers exceeded the number of pages, which would usually
be the case.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

After some initcall traces, some initcall names may be inconsistent.
That's because these functions will disappear from the .init section
and also their name from the symbols table.

So we have to copy the name of the function in a buffer large enough
during the trace appending. It is not costly for the ring_buffer because
the number of initcall entries is commonly not really large.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Change the boot tracer printing to make it parsable for
the scripts/bootgraph.pl script.

We have now to output two lines for each initcall, according to the
printk in do_one_initcall() in init/main.c
We need now the call's time and the return's time.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 kernel/trace/ring_buffer.c: In function ‘rb_allocate_pages’:
 kernel/trace/ring_buffer.c:235: error: ‘cpu’ undeclared (first use in this function)
 kernel/trace/ring_buffer.c:235: error: (Each undeclared identifier is reported only once
 kernel/trace/ring_buffer.c:235: error: for each function it appears in.)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

With the new ring buffer infrastructure in ftrace, I'm trying to make
ftrace a little more light weight.

This patch converts a lot of the local_irq_save/restore into
preempt_disable/enable.  The original preempt count in a lot of cases
has to be sent in as a parameter so that it can be recorded correctly.
Some places were recording it incorrectly before anyway.

This is also laying the ground work to make ftrace a little bit
more reentrant, and remove all locking. The function tracers must
still protect from reentrancy.

Note: All the function tracers must be careful when using preempt_disable.
  It must do the following:

  resched = need_resched();
  preempt_disable_notrace();
  [...]
  if (resched)
	preempt_enable_no_resched_notrace();
  else
	preempt_enable_notrace();

The reason is that if this function traces schedule() itself, the
preempt_enable_notrace() will cause a schedule, which will lead
us into a recursive failure.

If we needed to reschedule before calling preempt_disable, we
should have already scheduled. Since we did not, this is most
likely that we should not and are probably inside a schedule
function.

If resched was not set, we still need to catch the need resched
flag being set when preemption was off and the if case at the
end will catch that for us.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The current method of overlaying the page frame as the buffer page pointer
can be very dangerous and limits our ability to do other things with
a page from the buffer, like send it off to disk.

This patch allocates the buffer_page instead of overlaying the page's
page frame. The use of the buffer_page has hardly changed due to this.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The mmiotrace map had a bug that would typecast the entry from
the trace to the wrong type. That is a known danger of C typecasts,
there's absolutely zero checking done on them.

Help that problem a bit by using a GCC extension to implement a
type filter that restricts the types that a trace record can be
cast into, and by adding a dynamic check (in debug mode) to verify
the type of the entry.

This patch adds a macro to assign all entries of ftrace using the type
of the variable and checking the entry id. The typecasts are now done
in the macro for only those types that it knows about, which should
be all the types that are allowed to be read from the tracer.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>