It is useful to know the QEMU process ID when working with traces from
multiple VMs.  Although the trace filename may contain the pid, tools
that aggregate traces or even trace globally need somewhere to record
the pid.

There is a reserved field in the trace event header struct that we can
use.

It is not necessary to bump the simpletrace file format version number
because it has already been incremented for the QEMU 2.1 release cycle
in commit "trace: [simple] Bump up log version number".
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The following tracetool cleanup changes the event numbering policy.
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

glib versions prior to 2.31.0 require an explicit g_thread_init() call
to enable multi-threading.

Failure to initialize threading causes glib to take single-threaded code
paths without synchronization.  For example, the g_slice allocator will
crash due to race conditions.

Fix this for all QEMU tool programs (qemu-nbd, qemu-io, qemu-img) by
moving the g_thread_init() call from vl.c:main() into a new
osdep.c:thread_init() constructor function.

thread_init() has __attribute__((constructor)) and is automatically
invoked by the runtime during startup.

We can now drop the "simple" trace backend's g_thread_init() call since
thread_init() already called it.

Note that we must keep coroutine-gthread.c's g_thread_init() call which
is located in a constructor function.  There is no guarantee for
constructor function ordering so thread_init() may only be called later.
Reported-by: NMario de Chenno <mario.dechenno@unina2.it>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The GStaticMutex API was deprecated in glib 2.32.  We cannot switch over
to GMutex unconditionally since we would drop support for older glib
versions.  But the deprecated API warnings during build are annoying so
use static GMutex when possible.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The header is not necessary, given that the simple backend does not define any
inlined tracing routines.
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The backend is forced to dump event numbers using 64 bits, as TraceEventID is
an enum.
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

g_thread_create() was deprecated in favor of g_thread_new() and
g_cond_new() was deprecated in favor of GCond initialization.  If the
host has glib 2.31 or newer, avoid using the deprecated functions.

This patch solves compiler warnings that are generated when glib's
deprecated functions are used.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1360676045-9204-3-git-send-email-stefanha@redhat.com
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Juan reported that RHEL 6.4 hosts give compiler warnings because we use
unsigned int while glib prototypes use volatile gint in trace/simple.c.

  trace/simple.c:223: error: pointer targets in passing argument 1 of 'g_atomic_int_compare_and_exchange' differ in signedness

These variables are only accessed with glib atomic int functions so
let's play it by the book and use volatile gint.
Reported-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1360676045-9204-2-git-send-email-stefanha@redhat.com
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The GLib Reference Manual says:

    It is very important that all accesses to a particular integer or
    pointer be performed using only this API and that different sizes
    of operation are not mixed or used on overlapping memory
    regions. Never read or assign directly from or to a value --
    always use this API.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

We use atomic operations to keep track of dropped events.

Inconveniently, GLib supports only int and void * atomics, but the
counter dropped_events is uint64_t.  Can't stop commit 62bab732: a
quick (gint *)&dropped_events bludgeons the compiler into submission.

That cast is okay only when int is exactly 64 bits wide, which it
commonly isn't.

If int is even wider, we clobber whatever follows dropped_events.  Not
worth worrying about, as none of the machines that interest us have
such morbidly obese ints.

That leaves the common case: int narrower than 64 bits.

Harmless on little endian hosts: we just don't access the most
significant bits of dropped_events.  They remain zero.

On big endian hosts, we use only the most significant bits of
dropped_events as counter.  The least significant bits remain zero.
However, we write out the full value, which is the correct counter
shifted left a bunch of places.

Fix by changing the variables involved to int.

There's another, equally suspicious-looking (gint *)&trace_idx
argument to g_atomic_int_compare_and_exchange(), but that one casts
unsigned *, so it's okay.  But it's also superfluous, because GLib's
atomic int operations work just fine for unsigned.  Drop it.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

asprintf is not available for all hosts. g_strdup_printf is
more portable and simplifies the code because if does not
need error handling.

The static variable does not need an explicit assignment to be NULL.

Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Declaring a TraceRecord on the stack works fine.  No need for a
uint8_t array and pointer aliasing.
Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

The buffer argument is void* so it is not necessary to cast.
Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

The TraceRecordHeader is really the header for the entire trace log
file.  It's not per-record header so make this obvious by renaming it.
Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Existing simpletrace backend allows to trace at max 6 args and does not
support strings. This newer tracelog format gets rid of fixed size records
and therefore allows to trace variable number of args including strings.

Sample trace with strings:
v9fs_version 0.000 tag=0xffff id=0x64 msize=0x2000 version=9P2000.L
v9fs_version_return 6.705 tag=0xffff id=0x64 msize=0x2000 version=9P2000.L
Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Going forward with simpletrace v2 variable size trace records, we cannot
have a generic function to print trace event info and therefore this
interface becomes invalid.

As per Stefan Hajnoczi:

"This command is only available from the human monitor.  It's not very
useful because it historically hasn't been able to pretty-print events
or show them in the right order (we use a ringbuffer but it prints
them out from index 0).

Therefore, I don't think we're under any obligation to keep this
command around.  No one has complained about it's limitations - I
think this is a sign that no one has used it.  I'd be okay with a
patch that removes it."

Ref: http://lists.gnu.org/archive/html/qemu-devel/2012-01/msg01268.htmlSigned-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

This patch makes trace_thread_create() to use its function arg to
initialize thread.  The other choice is to make this a function to use
void arg, but i prefer this way.
Signed-off-by: NJun Koi <junkoi2004@gmail.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

since commit f9b29ca03 included in release 2.31 (docs below say 2.32 but
that is not correct) and onwards g_thread_init is deprecated and calling
it is not required:

 http://developer.gnome.org/glib/unstable/glib-Deprecated-Thread-APIs.html#g-thread-init

 g_thread_init has been deprecated since version 2.32 and should not be
 used in newly-written code. This function is no longer necessary. The
 GLib threading system is automatically initialized at the start of your
 program.

Fixes bulid failure when warnings are treated as errors on fedora 17.

I only tested the change to vl.c, and copy pasted to the two other
locations (couldn't decide if a wrapper for calling g_thread_init is
uglier).
Signed-off-by: NAlon Levy <alevy@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

A basic wildcard matching is supported in both the monitor command
"trace-event" and the events list file. That means you can enable/disable
the events having a common prefix in a batch. For example, virtio-blk trace
events could be enabled using:
    trace-event virtio_blk_* on
Signed-off-by: NMark Wu <wudxw@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

For Windows portability the simple trace backend must use the 'b' file
open mode.  This prevents the stdio library from mangling 0x0a/0x0d
newline characters.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Convert the simple trace backend to glib so that it works under Windows.
We cannot use pthread directly but glib provides portable abstractions.
Also use glib atomics instead of newish gcc builtins which may not be
supported on Windows toolchains.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

The "-trace events" argument can be used to provide a file with a list of trace
event names that will be enabled prior to starting execution, thus providing
early tracing.

This saves the user from manually toggling event states through the monitor
interface or whichever backend-specific interface.
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>

Generalize the 'st_print_trace_events' and 'st_change_trace_event_state' into
backend-specific 'trace_print_events' and 'trace_event_set_state' (respectively)
in the "trace/control.h" file.
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>

A default implementation for backend-specific routines is provided in
"trace/default.c", which backends can override by setting "trace_default=no" in
"configure".
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>

Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>

Avoid this warning:
  CC    simpletrace.o
/src/qemu/simpletrace.c: In function 'writeout_thread':
/src/qemu/simpletrace.c:122:12: error: variable 'unused' set but not used [-Werror=unused-but-set-variable]
by adding GCC attribute unused to the variable.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

User emulator builds do not have error_report() so it should not be used
by simpletrace.c.  In fact, error reporting inside simpletrace.c is
inappropriate and should be done by the caller instead.

This patch moves st_init() error reporting out to its caller,
vl.c:main().
Reported-by: NBlue Swirl <blauwirbel@gmail.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Trace events outside the global mutex cannot be used with the simple
trace backend since it is not thread-safe.  There is no check to prevent
them being enabled so people sometimes learn this the hard way.

This patch restructures the simple trace backend with a ring buffer
suitable for multiple concurrent writers.  A writeout thread empties the
trace buffer when threshold fill levels are reached.  Should the
writeout thread be unable to keep up with trace generation, records will
simply be dropped.

Each time events are dropped a special record is written to the trace
file indicating how many events were dropped.  The event ID is
0xfffffffffffffffe and its signature is dropped(uint32_t count).
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Move timer init functions to a new file, qemu-timer-common.c. Make other
critical timer functions inlined to preserve performance in
qemu-timer.c, also move muldiv64() (used by the inline functions)
to qemu-timer.h.

Adjust block/raw-posix.c and simpletrace.c to use get_clock() directly.
Remove a similar/duplicate definition in qemu-tool.c.

Adjust hw/omap_clk.c to include qemu-timer.h because muldiv64() is used
there.

After this change, tracing can be used also for user code and
simpletrace on Win32.

Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Acked-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Use PRI*64 to print full 64 bit data even on ILP32 hosts.

Print also sixth tracepoint parameter.
Acked-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

There was no warning if a bad trace event name was given to
'trace-event' command, thus the user could think that the command
was successful even if this was not the case.

Print a warning if the user tries to enable a trace event which is not
known.
Acked-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

This patch adds the trace-file command:

  trace-file [on|off|flush]

  Open, close, or flush the trace file.  If no argument is given,
  the status of the trace file is displayed.

The trace file is turned on by default but is only written out when the
trace buffer becomes full.  The flush operation can be used to force
write out at any time.

Turning off the trace file does not change the state of trace events;
tracing will continue to the trace buffer.  When the trace file is off,
use "info trace" to display the contents of the trace buffer in memory.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

This commit also contains the trace-file sub-command from the following
commit:

commit 5ce8d1a957afae2c52ad748944ce72848ccf57bd
Author: Prerna Saxena <prerna@linux.vnet.ibm.com>
Date:   Wed Aug 4 16:23:54 2010 +0530

    trace: Add options to specify trace file name at startup and runtime

    This patch adds an optional command line switch '-trace' to specify the
    filename to write traces to, when qemu starts.
    Eg, If compiled with the 'simple' trace backend,
    [temp@system]$ qemu -trace FILENAME IMAGE
    Allows the binary traces to be written to FILENAME instead of the option
    set at config-time.

    Also, this adds monitor sub-command 'set' to trace-file commands to
    dynamically change trace log file at runtime.
    Eg,
    (qemu)trace-file set FILENAME
    This allows one to set trace outputs to FILENAME from the default
    specified at startup.
Signed-off-by: NPrerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Allow users to specify a file for trace-outputs at configuration.
Also, allow trace files to be annotated by <pid> so each qemu instance has
unique traces.

The trace file name can be passed as a config option:
--trace-file=/path/to/file
(Default: trace )
At runtime, the pid of the qemu process is appended to the filename so
that mutiple qemu instances do not have overlapping logs.

Eg : trace-1234 for qemu launched with pid 1234.

I have yet to test this on windows. getpid() is used at many places
in code(including vnc.c), so I'm hoping this would be okay too.
Edited-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

This patch adds support for dynamically enabling/disabling of trace events.
This is done by internally maintaining each trace event's state, and
permitting logging of data from a trace event only if it is in an
'active' state.

Monitor commands added :
1) info trace-events 		: to view all available trace events and
				  their state.
2) trace-event NAME on|off 	: to enable/disable data logging from a
				  given trace event.
				  Eg, trace-event paio_submit off
				  	disables logging of data when
					paio_submit is hit.

By default, all trace-events are disabled. One can enable desired trace-events
via the monitor.
Signed-off-by: NPrerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

trace: Monitor command 'info trace'

Monitor command 'info trace' to display contents of trace buffer
Signed-off-by: NPrerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

trace: Remove monitor.h dependency from simpletrace

User-mode targets don't have a monitor so the simple trace backend
currently does not build on those targets.  This patch abstracts the
monitor printing interface so there is no direct coupling between
simpletrace and the monitor.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

This patch adds a simple tracer which produces binary trace files.  To
try out the simple backend:

$ ./configure --trace-backend=simple
$ make

After running QEMU you can pretty-print the trace:

$ ./simpletrace.py trace-events trace.log

The output of simpletrace.py looks like this:

  qemu_realloc 0.699 ptr=0x24363f0 size=0x3 newptr=0x24363f0
  qemu_free 0.768 ptr=0x24363f0
  ^           ^---- timestamp delta (us)
  |____ trace event name
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

trace: Make trace record fields 64-bit

Explicitly use 64-bit fields in trace records so that timestamps and
magic numbers work for 32-bit host builds.

Includes fixes from Prerna Saxena <prerna@linux.vnet.ibm.com>.
Signed-off-by: NPrerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>