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Merge remote-tracking branch 'remotes/stefanha/tags/tracing-pull-request' into staging

# gpg: Signature made Tue 15 Aug 2017 14:27:34 BST
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/tracing-pull-request:
  simpletrace: fix flight recorder --no-header option
  trace: use static event ID mapping in simpletrace.stp

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

scripts/simpletrace.py

@@ -97,11 +97,17 @@ def read_trace_header(fobj):
         raise ValueError('Log format %d not supported with this QEMU release!'
                          % log_version)
 
-def read_trace_records(edict, fobj):
-    """Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6)."""
-    idtoname = {
-        dropped_event_id: "dropped"
-    }
+def read_trace_records(edict, idtoname, fobj):
+    """Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6).
+
+    Note that `idtoname` is modified if the file contains mapping records.
+
+    Args:
+        edict (str -> Event): events dict, indexed by name
+        idtoname (int -> str): event names dict, indexed by event ID
+        fobj (file): input file
+
+    """
     while True:
         t = fobj.read(8)
         if len(t) == 0:
@@ -171,10 +177,16 @@ def process(events, log, analyzer, read_header=True):
 
     dropped_event = Event.build("Dropped_Event(uint64_t num_events_dropped)")
     edict = {"dropped": dropped_event}
+    idtoname = {dropped_event_id: "dropped"}
 
     for event in events:
         edict[event.name] = event
 
+    # If there is no header assume event ID mapping matches events list
+    if not read_header:
+        for event_id, event in enumerate(events):
+            idtoname[event_id] = event.name
+
     def build_fn(analyzer, event):
         if isinstance(event, str):
             return analyzer.catchall
@@ -197,7 +209,7 @@ def process(events, log, analyzer, read_header=True):
 
     analyzer.begin()
     fn_cache = {}
-    for rec in read_trace_records(edict, log):
+    for rec in read_trace_records(edict, idtoname, log):
         event_num = rec[0]
         event = edict[event_num]
         if event_num not in fn_cache:

scripts/tracetool/format/simpletrace_stap.py

@@ -22,33 +22,8 @@ def global_var_name(name):
     return probeprefix().replace(".", "_") + "_" + name
 
 def generate(events, backend, group):
-    id_map = global_var_name("event_name_to_id_map")
-    next_id = global_var_name("event_next_id")
-    map_func = global_var_name("simple_trace_map_event")
     out('/* This file is autogenerated by tracetool, do not edit. */',
-        '',
-        'global %(id_map)s',
-        'global %(next_id)s',
-        'function %(map_func)s(name)',
-        '',
-        '{',
-        '    if (!([name] in %(id_map)s)) {',
-        '        %(id_map)s[name] = %(next_id)s',
-        '        name_len = strlen(name)',
-        '        printf("%%8b%%8b%%4b%%.*s", 0, ',
-        '               %(next_id)s, name_len, name_len, name)',
-        '        %(next_id)s = %(next_id)s + 1',
-        '    }',
-        '    return %(id_map)s[name]',
-        '}',
-        'probe begin',
-        '{',
-        '    printf("%%8b%%8b%%8b", 0xffffffffffffffff, 0xf2b177cb0aa429b4, 4)',
-        '}',
-        '',
-        id_map=id_map,
-        next_id=next_id,
-        map_func=map_func)
+        '')
 
     for event_id, e in enumerate(events):
         if 'disable' in e.properties:
@@ -56,9 +31,7 @@ def generate(events, backend, group):
 
         out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',
             '{',
-            '    id = %(map_func)s("%(name)s")',
             probeprefix=probeprefix(),
-            map_func=map_func,
             name=e.name)
 
         # Calculate record size
@@ -77,7 +50,7 @@ def generate(events, backend, group):
         sizestr = ' + '.join(sizes)
 
         # Generate format string and value pairs for record header and arguments
-        fields = [('8b', 'id'),
+        fields = [('8b', str(event_id)),
                   ('8b', 'gettimeofday_ns()'),
                   ('4b', sizestr),
                   ('4b', 'pid()')]