Commit ea1ff54f authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Stefan Hajnoczi
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trace: ensure unique function / variable names per .stp file 



The simpletrace compatibility code for systemtap creates a
function and some global variables for mapping to event ID
numbers. We generate multiple -simpletrace.stp files though,
one per target and systemtap considers functions & variables
to be globally scoped, not per file. So if trying to use the
simpletrace compat probes, systemtap will complain:

 # stap -e 'probe qemu.system.arm.simpletrace.visit_type_str { print( "hello")}'
 semantic error: conflicting global variables: identifier 'event_name_to_id_map' at /usr/share/systemtap/tapset/qemu-aarch64-simpletrace.stp:3:8
        source: global event_name_to_id_map
                       ^
 identifier 'event_name_to_id_map' at /usr/share/systemtap/tapset/qemu-system-arm-simpletrace.stp:3:8
        source: global event_name_to_id_map
                       ^

 WARNING: cross-file global variable reference to identifier 'event_name_to_id_map' at /usr/share/systemtap/tapset/qemu-system-arm-simpletrace.stp:3:8 from: identifier 'event_name_to_id_map' at /usr/share/systemtap/tapset/qemu-aarch64-simpletrace.stp:8:21
 source:     if (!([name] in event_name_to_id_map)) {
                             ^
 WARNING: cross-file global variable reference to identifier 'event_next_id' at /usr/share/systemtap/tapset/qemu-system-arm-simpletrace.stp:4:8 from: identifier 'event_next_id' at :9:38
 source:         event_name_to_id_map[name] = event_next_id
                                              ^

We already have a string used to prefix probe names, so just
replace '.' with '_' to get a function / variable name prefix

Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170728133657.5525-1-berrange@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent ed865058

scripts/tracetool/format/simpletrace_stap.py

+19 −10
Original line number Diff line number Diff line
@@ -18,29 +18,37 @@ from tracetool.backend.dtrace import binary, probeprefix 
from tracetool.backend.simple import is_string

from tracetool.format.stap import stap_escape



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 event_name_to_id_map',

        'global event_next_id',

        'function simple_trace_map_event(name)',

        'global %(id_map)s',

        'global %(next_id)s',

        'function %(map_func)s(name)',

        '',

        '{',

        '    if (!([name] in event_name_to_id_map)) {',

        '        event_name_to_id_map[name] = event_next_id',

        '    if (!([name] in %(id_map)s)) {',

        '        %(id_map)s[name] = %(next_id)s',

        '        name_len = strlen(name)',

        '        printf("%%8b%%8b%%4b%%.*s", 0, ',

        '               event_next_id, name_len, name_len, name)',

        '        event_next_id = event_next_id + 1',

        '               %(next_id)s, name_len, name_len, name)',

        '        %(next_id)s = %(next_id)s + 1',

        '    }',

        '    return event_name_to_id_map[name]',

        '    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:
@@ -48,8 +56,9 @@ def generate(events, backend, group): 


        out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',

            '{',

            '    id = simple_trace_map_event("%(name)s")',

            '    id = %(map_func)s("%(name)s")',

            probeprefix=probeprefix(),

            map_func=map_func,

            name=e.name)



        # Calculate record size