This parameter is needed by syscall events to add define_fields()
handler.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A8BAF90.6060801@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add the struct ftrace_event_call as a parameter of its show_format()
callback. This way we can use it from the syscall trace events to
retrieve the syscall name from the ftrace event call parameter and
describe its fields using the syscalls metadata.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>

add an optional void * pointer to 'ftrace_event_call' that is
passed in for regfunc and unregfunc.

This prepares for syscall tracepoints creation by passing the name of
the syscall we want to trace and then retrieve its number through our
arch syscall table.
Signed-off-by: NJason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

After aligning the ftrace raw samples, there are dead bytes storing
random data from the stack. We don't want to leak these to userspace,
then zero these out.

Before:

	0x2de88 [0x50]: event: 9
	.
	. ... raw event: size 80 bytes
	.  0000:  09 00 00 00 01 00 50 00 d0 c7 00 81 ff ff ff ff  ......P........
	.  0010:  68 01 00 00 68 01 00 00 2c 00 00 00 00 00 00 00  h...h...,......
	.  0020:  2c 00 00 00 2b 00 01 02 68 01 00 00 68 01 00 00  ,...+...h...h..
	.  0030:  6b 6f 6e 64 65 6d 61 6e 64 2f 30 00 00 00 00 00  kondemand/0....
	.  0040:  68 01 00 00 40 7f 46 81 ff ff ff ff 00 10 1b 7f  h...@.F........
                                                      ^  ^  ^  ^
                                                         Leak

After:

	0x2d318 [0x50]: event: 9
	.
	. ... raw event: size 80 bytes
	.  0000:  09 00 00 00 01 00 50 00 d0 c7 00 81 ff ff ff ff  ......P........
	.  0010:  68 01 00 00 68 01 00 00 68 14 00 00 00 00 00 00  h...h...h......
	.  0020:  2c 00 00 00 2b 00 01 02 68 01 00 00 68 01 00 00  ,...+...h...h..
	.  0030:  6b 6f 6e 64 65 6d 61 6e 64 2f 30 00 00 00 00 00  kondemand/0....
	.  0040:  68 01 00 00 a0 80 46 81 ff ff ff ff 00 00 00 00  h.....F........
                                                      ^  ^  ^  ^
							 Fixed
Reported-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1249915116-5210-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>

We compute the perf raw sample size by aligning the raw ftrace
event size plus the buffer size field itself. We do that
instead of aligning only the perf raw sample size, so that we
might economize some in some cases.

But this buffer size field is not stored in the perf raw
sample, we must then substract its size from the buffer once we
computed the alignment unless we may get a useless u32 field in
the buffer.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20090810141129.GA5124@nowhere>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

PERF_SAMPLE_* output switches should unconditionally output the
correct format, as they are the only way to unambiguously parse
the PERF_EVENT_SAMPLE data.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1249896447.17467.74.camel@twins>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch implements the kernel side support for ftrace event
record sampling.

A new counter sampling attribute is added:

   PERF_SAMPLE_TP_RECORD

which requests ftrace events record sampling. In this case
if a PERF_TYPE_TRACEPOINT counter is active and a tracepoint
fires, we emit the tracepoint binary record to the
perfcounter event buffer, as a sample.

Result, after setting PERF_SAMPLE_TP_RECORD attribute from perf
record:

 perf record -f -F 1 -a -e workqueue:workqueue_execution
 perf report -D

 0x21e18 [0x48]: event: 9
 .
 . ... raw event: size 72 bytes
 .  0000:  09 00 00 00 01 00 48 00 d0 c7 00 81 ff ff ff ff  ......H........
 .  0010:  0a 00 00 00 0a 00 00 00 21 00 00 00 00 00 00 00  ........!......
 .  0020:  2b 00 01 02 0a 00 00 00 0a 00 00 00 65 76 65 6e  +...........eve
 .  0030:  74 73 2f 31 00 00 00 00 00 00 00 00 0a 00 00 00  ts/1...........
 .  0040:  e0 b1 31 81 ff ff ff ff                          .......
.
0x21e18 [0x48]: PERF_EVENT_SAMPLE (IP, 1): 10: 0xffffffff8100c7d0 period: 33

The raw ftrace binary record starts at offset 0020.

Translation:

 struct trace_entry {
	type		= 0x2b = 43;
	flags		= 1;
	preempt_count	= 2;
	pid		= 0xa = 10;
	tgid		= 0xa = 10;
 }

 thread_comm = "events/1"
 thread_pid  = 0xa = 10;
 func	    = 0xffffffff8131b1e0 = flush_to_ldisc()

What will come next?

 - Userspace support ('perf trace'), 'flight data recorder' mode
   for perf trace, etc.

 - The unconditional copy from the profiling callback brings
   some costs however if someone wants no such sampling to
   occur, and needs to be fixed in the future. For that we need
   to have an instant access to the perf counter attribute.
   This is a matter of a flag to add in the struct ftrace_event.

 - Take care of the events recursivity! Don't ever try to record
   a lock event for example, it seems some locking is used in
   the profiling fast path and lead to a tracing recursivity.
   That will be fixed using raw spinlock or recursivity
   protection.

 - [...]

 - Profit! :-)
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Adds possible second part to the assign argument of TP_EVENT().

  TP_perf_assign(
	__perf_count(foo);
	__perf_addr(bar);
  )

Which, when specified make the swcounter increment with @foo instead
of the usual 1, and report @bar for PERF_SAMPLE_ADDR (data address
associated with the event) when this triggers a counter overflow.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When a dynamic array is defined, we add __data_loc_foo in
trace_entry to record the offset of the array, but the
size of the array is not recorded, which causes 2 problems:

- the event filter just compares the first 2 chars of the strings.

- parsers can't parse dynamic arrays.

So we encode the size of each dynamic array in the higher 16 bits
of __data_loc_foo, while the offset is in lower 16 bits.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A5E964A.9000403@cn.fujitsu.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The format file doesn't contain enough information for
__dynamic_array/__string. The type name is missing.

Before:
  # cat format:
  name: irq_handler_entry
  ...
          field:__data_loc name;  offset:16;      size:2;

After:
  # cat format:
  name: irq_handler_entry
  ...
          field:__data_loc char[] name;  offset:16;      size:2;
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4A5E962E.9020900@cn.fujitsu.com>
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

By moving the macro that creates the print format code above the
defining of the event macro helpers (__get_str, __print_symbolic,
and __get_dynamic_array), we get a little cleaner print format.

Instead of:

  (char *)((void *)REC + REC->__data_loc_name)

we get:

   __get_str(name)

Instead of:

   ({ static const struct trace_print_flags symbols[] = { { HI_SOFTIRQ, "HI" }, {

we get:

   __print_symbolic(REC->vec, { HI_SOFTIRQ, "HI" }, {
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Here is an updated patch to include the extra call to
trace_seq_init() as requested. This is vs. the latest
-tip tree and fixes the use of multiple __print_flags
and __print_symbolic in a single tracer. Also tested
to ensure its working now:

mount.gfs2-2534  [000]   235.850587: gfs2_glock_queue: 8.7 glock 1:2 dequeue PR
mount.gfs2-2534  [000]   235.850591: gfs2_demote_rq: 8.7 glock 1:0 demote EX to NL flags:DI
mount.gfs2-2534  [000]   235.850591: gfs2_glock_queue: 8.7 glock 1:0 dequeue EX
glock_workqueue-2529  [000]   235.850666: gfs2_glock_state_change: 8.7 glock 1:0 state EX => NL tgt:NL dmt:NL flags:lDpI
glock_workqueue-2529  [000]   235.850672: gfs2_glock_put: 8.7 glock 1:0 state NL => IV flags:I
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
LKML-Reference: <1244037123.29604.603.camel@localhost.localdomain>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

__string() is limited:

  - it's a char array, but we may want to define array with other types
  - a source string should be available, but we may just know the string size

We introduce __dynamic_array() to break those limitations, and __string()
becomes a wrapper of it. As a side effect, now __get_str() can be used
in TP_fast_assign but not only TP_print.

Take XFS for example, we have the string length in the dirent, but the
string itself is not NULL-terminated, so __dynamic_array() can be used:

TRACE_EVENT(xfs_dir2,
	TP_PROTO(struct xfs_da_args *args),
	TP_ARGS(args),

	TP_STRUCT__entry(
		__field(int, namelen)
		__dynamic_array(char, name, args->namelen + 1)
		...
	),

	TP_fast_assign(
		char *name = __get_str(name);

		if (args->namelen)
			memcpy(name, args->name, args->namelen);
		name[args->namelen] = '\0';

		__entry->namelen = args->namelen;
	),

	TP_printk("name %.*s namelen %d",
		  __entry->namelen ? __get_str(name) : NULL
		  __entry->namelen)
);

[ Impact: allow defining dynamic size arrays ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A2384D2.3080403@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently TP_fast_assign has a limitation that we can't define local
variables in it.

Here's one use case when we introduce __dynamic_array():

TP_fast_assign(
	type *p = __get_dynamic_array(item);

	foo(p);
	bar(p);
),

[ Impact: allow defining local variables in TP_fast_assign ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A2384B1.90100@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

"tsize" should be "\tsize". Also remove the space before "__str_loc".

Before:
 # cat tracing/events/irq/irq_handler_entry/format
        ...
        field:int irq;  offset:12;      size:4;
        field: __str_loc name;  offset:16;tsize:2;
        ...

After:
 # cat tracing/events/irq/irq_handler_entry/format
	...
        field:int irq;  offset:12;      size:4;
        field:__str_loc name;   offset:16;      size:2;
	...

[ Impact: standardize __string field description in events format file ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

"call" is an argument of macro, but it is also used as a local
variable name of function in macro.
We should keep this local variable name distinct from any
CPP macro parameter name if both are in the same macro scope,
although it hasn't caused any problem yet.

[ Impact: robustify macro ]
Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

This patch adds __print_symbolic which is similar to __print_flags but
works for an enumeration type instead. That is, there is only a one to one
mapping between the values and the symbols. When a match is made, then
it is printed, otherwise the hex value is outputed.

[ Impact: add interface for showing symbol names in events ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

Developers have been asking for the ability in the ftrace event tracer
to display names of bits in a flags variable.

Instead of printing out c2, it would be easier to read FOO|BAR|GOO,
assuming that FOO is bit 1, BAR is bit 6 and GOO is bit 7.

Some examples where this would be useful are the state flags in a context
switch, kmalloc flags, and even permision flags in accessing files.

[
  v2 changes include:

  Frederic Weisbecker's idea of using a mask instead of bits,
  thus we can output GFP_KERNEL instead of GPF_WAIT|GFP_IO|GFP_FS.

  Li Zefan's idea of allowing the caller of __print_flags to add their
  own delimiter (or no delimiter) where we can get for file permissions
  rwx instead of r|w|x.
]

[
  v3 changes:

   Christoph Hellwig's idea of using an array instead of va_args.
]

[ Impact: better displaying of flags in trace output ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

When defining a dynamic size string, we add __str_loc_##item to the
trace entry, and it stores the location of the actual string in
entry->_str_data[]

'unsigned short' should be sufficient to store this information, thus
we save 2 bytes per dyn-size string in the ring buffer.

[ Impact: reduce memory occupied by dyn-size strings in ring buffer ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A14EDB6.2050507@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

The new filter comparison ops need to be able to distinguish between
signed and unsigned field types, so add an is_signed flag/param to the
event field struct/trace_define_fields().  Also define a simple macro,
is_signed_type() to determine the signedness at compile time, used in the
trace macros.  If the is_signed_type() macro won't work with a specific
type, a new slightly modified version of TRACE_FIELD() called
TRACE_FIELD_SIGN(), allows the signedness to be set explicitly.

[ Impact: extend trace-filter code for new feature ]
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: fweisbec@gmail.com
Cc: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <1240905893.6416.120.camel@tropicana>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The TRACE_FORMAT macro has been deprecated by the TRACE_EVENT macro.
There are no more users. All new users must use the TRACE_EVENT macro.

[ Impact: remove old functionality ]

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The __get_str() macro is used in a code part then its content should be
protected with parenthesis.

[ Impact: make macro definition more robust ]
Reported-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

This patch provides the support for dynamic size strings on
event tracing.

The key concept is to use a structure with an ending char array field of
undefined size and use such ability to allocate the minimal size on the
ring buffer to make one or more string entries fit inside, as opposite
to a fixed length strings with upper bound.

The strings themselves are represented using fields which have an offset
value from the beginning of the entry.

This patch provides three new macros:

__string(item, src)

This one declares a string to the structure inside TP_STRUCT__entry.
You need to provide the name of the string field and the source that will
be copied inside.
This will also add the dynamic size of the string needed for the ring
buffer entry allocation.
A stack allocated structure is used to temporarily store the offset
of each strings, avoiding double calls to strlen() on each event
insertion.

__get_str(field)

This one will give you a pointer to the string you have created. This
is an abstract helper to resolve the absolute address given the field
name which is a relative address from the beginning of the trace_structure.

__assign_str(dst, src)

Use this macro to automatically perform the string copy from src to
dst. src must be a variable to assign and dst is the name of a __string
field.

Example on how to use it:

TRACE_EVENT(my_event,
	TP_PROTO(char *src1, char *src2),

	TP_ARGS(src1, src2),
	TP_STRUCT__entry(
		__string(str1, src1)
		__string(str2, src2)
	),
	TP_fast_assign(
		__assign_str(str1, src1);
		__assign_str(str2, src2);
	),
	TP_printk("%s %s", __get_str(src1), __get_str(src2))
)

Of course you can mix-up any __field or __array inside this
TRACE_EVENT. The position of the __string or __assign_str
doesn't matter.

Changes in v2:

Address the suggestion of Steven Rostedt: drop the opening_string() macro
and redefine __ending_string() to get the size of the string to be copied
instead of overwritting the whole ring buffer allocation.

Changes in v3:

Address other suggestions of Steven Rostedt and Peter Zijlstra with
some changes: drop the __ending_string and the need to have only one
string field.
Use offsets instead of absolute addresses.

[ Impact: allow more compact memory usage for string tracing ]
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>

struct trace_entry->type is unsigned char, while trace event's id is
int type, thus for a event with id >= 256, it's entry->type is cast
to (id % 256), and then we can't see the trace output of this event.

 # insmod trace-events-sample.ko
 # echo foo_bar > /mnt/tracing/set_event
 # cat /debug/tracing/events/trace-events-sample/foo_bar/id
 256
 # cat /mnt/tracing/trace_pipe
           <...>-3548  [001]   215.091142: Unknown type 0
           <...>-3548  [001]   216.089207: Unknown type 0
           <...>-3548  [001]   217.087271: Unknown type 0
           <...>-3548  [001]   218.085332: Unknown type 0

[ Impact: fix output for trace events with id >= 256 ]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <49EEDB0E.5070207@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Tracepoints with no arguments can issue two warnings:

	"field" defined by not used
	"ret" is uninitialized in this function

Mark field as being OK to leave unused, and initialize ret.

[ Impact: fix false positive compiler warnings. ]
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: mathieu.desnoyers@polymtl.ca
LKML-Reference: <1239950139-1119-5-git-send-email-jeremy@goop.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: allow modules to add TRACE_EVENTS on load

This patch adds the final hooks to allow modules to use the TRACE_EVENT
macro. A notifier and a data structure are used to link the TRACE_EVENTs
defined in the module to connect them with the ftrace event tracing system.

It also adds the necessary automated clean ups to the trace events when a
module is removed.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch moves the ftrace creation into include/trace/ftrace.h and
simplifies the work of developers in adding new tracepoints.
Just the act of creating the trace points in include/trace and including
define_trace.h will create the events in the debugfs/tracing/events
directory.

This patch removes the need of include/trace/trace_events.h
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Impact: clean up

Neil Horman (et. al.) criticized the way the trace events were broken up
into two files. The reason for that was that ftrace needed to separate out
the declarations from where the #include <linux/tracepoint.h> was used.
It then dawned on me that the tracepoint.h header only needs to define the
TRACE_EVENT macro if it is not already defined.

The solution is simply to test if TRACE_EVENT is defined, and if it is not
then the linux/tracepoint.h header can define it. This change consolidates
all the <traces>.h and <traces>_event_types.h into the <traces>.h file.
Reported-by: NNeil Horman <nhorman@tuxdriver.com>
Reported-by: NTheodore Tso <tytso@mit.edu>
Reported-by: NJiaying Zhang <jiayingz@google.com>
Cc: Zhaolei <zhaolei@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch allows event filters to be safely removed or switched
on-the-fly while avoiding the use of rcu or the suspension of tracing of
previous versions.

It does it by adding a new filter_pred_none() predicate function which
does nothing and by never deallocating either the predicates or any of
the filter_pred members used in matching; the predicate lists are
allocated and initialized during ftrace_event_calls initialization.

Whenever a filter is removed or replaced, the filter_pred_* functions
currently in use by the affected ftrace_event_call are immediately
switched over to to the filter_pred_none() function, while the rest of
the filter_pred members are left intact, allowing any currently
executing filter_pred_* functions to finish up, using the values they're
currently using.

In the case of filter replacement, the new predicate values are copied
into the old predicates after the above step, and the filter_pred_none()
functions are replaced by the filter_pred_* functions for the new
filter.  In this case, it is possible though very unlikely that a
previous filter_pred_* is still running even after the
filter_pred_none() switch and the switch to the new filter_pred_*.  In
that case, however, because nothing has been deallocated in the
filter_pred, the worst that can happen is that the old filter_pred_*
function sees the new values and as a result produces either a false
positive or a false negative, depending on the values it finds.

So one downside to this method is that rarely, it can produce a bad
match during the filter switch, but it should be possible to live with
that, IMHO.

The other downside is that at least in this patch the predicate lists
are always pre-allocated, taking up memory from the start.  They could
probably be allocated on first-use, and de-allocated when tracing is
completely stopped - if this patch makes sense, I could create another
one to do that later on.

Oh, and it also places a restriction on the size of __arrays in events,
currently set to 128, since they can't be larger than the now embedded
str_val arrays in the filter_pred struct.
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: paulmck@linux.vnet.ibm.com
LKML-Reference: <1239610670.6660.49.camel@tropicana>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch changes filter_check_discard() to make use of the new
ring_buffer_discard_commit() function and modifies the current users to
call the old commit function in the non-discard case.

It also introduces a version of filter_check_discard() that uses the
global trace buffer (filter_current_check_discard()) for those cases.

v2 changes:

- fix compile error noticed by Ingo Molnar
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1239178554.10295.36.camel@tropicana>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The ring_buffer_discard_commit makes better usage of the ring_buffer
when an event has been discarded. It tries to remove it completely if
possible.

This patch converts the trace event filtering to use
ring_buffer_discard_commit instead of the ring_buffer_event_discard.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When we want to filter an event, the filter test is done after
the event is commited to the ring-buffer to be discarded later if
needed.

But a reader could be reading this event while we are trying to discard
it. Other kind of racy events can even happen because the event is
commited and can be read and/or consumed.

What we want is to discard the event before committing it.
Reported-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237763919-21505-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix hard-lockup with sched switch events

Some ftrace events, such as sched wakeup, can be traced
while the runqueue lock is hold. Since they are using
trace_current_buffer_unlock_commit(), they call wake_up()
which can try to grab the runqueue lock too, resulting in
a deadlock.

Now for all event, we call a new helper:
trace_nowake_buffer_unlock_commit() which do pretty the same than
trace_current_buffer_unlock_commit() except than it doesn't call
trace_wake_up().
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch adds per-event filtering to the event tracing subsystem.

It adds a 'filter' debugfs file to each event directory.  This file can
be written to to set filters; reading from it will display the current
set of filters set for that event.

Basically, any field listed in the 'format' file for an event can be
filtered on (including strings, but not yet other array types) using
either matching ('==') or non-matching ('!=') 'predicates'.  A
'predicate' can be either a single expression:

 # echo pid != 0 > filter

 # cat filter
 pid != 0

or a compound expression of up to 8 sub-expressions combined using '&&'
or '||':

 # echo comm == Xorg > filter
 # echo "&& sig != 29" > filter

 # cat filter
 comm == Xorg
 && sig != 29

Only events having field values matching an expression will be available
in the trace output; non-matching events are discarded.

Note that a compound expression is built up by echoing each
sub-expression separately - it's not the most efficient way to do
things, but it keeps the parser simple and assumes that compound
expressions will be relatively uncommon.  In any case, a subsequent
patch introducing a way to set filters for entire subsystems should
mitigate any need to do this for lots of events.

Setting a filter without an '&&' or '||' clears the previous filter
completely and sets the filter to the new expression:

 # cat filter
 comm == Xorg
 && sig != 29

 # echo comm != Xorg

 # cat filter
 comm != Xorg

To clear a filter, echo 0 to the filter file:

 # echo 0 > filter
 # cat filter
 none

The limit of 8 predicates for a compound expression is arbitrary - for
efficiency, it's implemented as an array of pointers to predicates, and
8 seemed more than enough for any filter...
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710665.7703.48.camel@charm-linux>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch makes the field descriptions defined for event tracing
available at run-time, for the event-filtering mechanism introduced
in a subsequent patch.

The common event fields are prepended with 'common_' in the format
display, allowing them to be distinguished from the other fields
that might internally have same name and can therefore be
unambiguously used in filters.
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: new tracing infrastructure feature

Provide infrastructure to generate software perf counter events
from tracepoints.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.557364871@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: widen user-space visibe event IDs to all events

Previously only TRACE_EVENT events got ids, because only they
generated raw output which needs to be demuxed from the trace.

In order to provide a unique ID for each event, register everybody,
regardless.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.464914218@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up

There existed a lot of <space><tab>'s in the tracing code. This
patch removes them.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up / comments

The comments that described the ftrace macros to manipulate the
TRACE_EVENT and TRACE_FORMAT macros no longer match the code.
This patch updates them.
Reported-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

In trying to stay consistant with the C style format in the TRACE_EVENT
macro, it makes more sense to do the printk after the assigning of
the variables.
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>