3932ef3ffb
QEMU keeps track of trace event enabled/disabled state and provides
monitor commands to inspect and modify the "dstate". SystemTap and
LTTng UST maintain independent enabled/disabled states for each trace
event, the other backends rely on QEMU dstate.
Introduce a new per-event macro that combines backend-specific dstate
like this:
#define TRACE_MY_EVENT_BACKEND_DSTATE() ( \
QEMU_MY_EVENT_ENABLED() || /* SystemTap */ \
tracepoint_enabled(qemu, my_event) /* LTTng UST */ || \
false)
This will be used to extend trace_event_get_state() in the next patch.
[Daniel Berrange pointed out that QEMU_MY_EVENT_ENABLED() must be true
by default, not false. This way events will fire even if the DTrace
implementation does not implement the SystemTap semaphores feature.
Ubuntu Precise uses lttng-ust-dev 2.0.2 which does not have
tracepoint_enabled(), so we need a compatibility wrapper to keep Travis
builds passing.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170731140718.22010-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
fixup! trace: add TRACE_<event>_BACKEND_DSTATE()
113 lines
3.1 KiB
Python
113 lines
3.1 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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"""
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Simple built-in backend.
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"""
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__author__ = "Lluís Vilanova <vilanova@ac.upc.edu>"
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__copyright__ = "Copyright 2012-2017, Lluís Vilanova <vilanova@ac.upc.edu>"
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__license__ = "GPL version 2 or (at your option) any later version"
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__maintainer__ = "Stefan Hajnoczi"
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__email__ = "stefanha@linux.vnet.ibm.com"
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from tracetool import out
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PUBLIC = True
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def is_string(arg):
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strtype = ('const char*', 'char*', 'const char *', 'char *')
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arg_strip = arg.lstrip()
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if arg_strip.startswith(strtype) and arg_strip.count('*') == 1:
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return True
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else:
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return False
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def generate_h_begin(events, group):
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for event in events:
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out('void _simple_%(api)s(%(args)s);',
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api=event.api(),
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args=event.args)
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out('')
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def generate_h(event, group):
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out(' _simple_%(api)s(%(args)s);',
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api=event.api(),
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args=", ".join(event.args.names()))
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def generate_h_backend_dstate(event, group):
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out(' trace_event_get_state_dynamic_by_id(%(event_id)s) || \\',
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event_id="TRACE_" + event.name.upper())
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def generate_c_begin(events, group):
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out('#include "qemu/osdep.h"',
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'#include "trace/control.h"',
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'#include "trace/simple.h"',
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'')
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def generate_c(event, group):
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out('void _simple_%(api)s(%(args)s)',
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'{',
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' TraceBufferRecord rec;',
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api=event.api(),
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args=event.args)
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sizes = []
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for type_, name in event.args:
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if is_string(type_):
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out(' size_t arg%(name)s_len = %(name)s ? MIN(strlen(%(name)s), MAX_TRACE_STRLEN) : 0;',
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name=name)
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strsizeinfo = "4 + arg%s_len" % name
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sizes.append(strsizeinfo)
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else:
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sizes.append("8")
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sizestr = " + ".join(sizes)
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if len(event.args) == 0:
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sizestr = '0'
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event_id = 'TRACE_' + event.name.upper()
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if "vcpu" in event.properties:
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# already checked on the generic format code
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cond = "true"
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else:
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cond = "trace_event_get_state(%s)" % event_id
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out('',
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' if (!%(cond)s) {',
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' return;',
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' }',
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'',
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' if (trace_record_start(&rec, %(event_obj)s.id, %(size_str)s)) {',
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' return; /* Trace Buffer Full, Event Dropped ! */',
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' }',
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cond=cond,
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event_obj=event.api(event.QEMU_EVENT),
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size_str=sizestr)
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if len(event.args) > 0:
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for type_, name in event.args:
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# string
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if is_string(type_):
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out(' trace_record_write_str(&rec, %(name)s, arg%(name)s_len);',
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name=name)
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# pointer var (not string)
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elif type_.endswith('*'):
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out(' trace_record_write_u64(&rec, (uintptr_t)(uint64_t *)%(name)s);',
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name=name)
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# primitive data type
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else:
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out(' trace_record_write_u64(&rec, (uint64_t)%(name)s);',
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name=name)
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out(' trace_record_finish(&rec);',
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'}',
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'')
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