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

Pull request

Fix --enable-modules --enable-trace-backends=dtrace with recent SystemTap
releases.

# gpg: Signature made Thu 19 Nov 2020 16:47:33 GMT
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha-gitlab/tags/tracing-pull-request:
  trace: use STAP_SDT_V2 to work around symbol visibility

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

configure

@@ -4832,6 +4832,13 @@ if have_backend "dtrace"; then
   trace_backend_stap="no"
   if has 'stap' ; then
     trace_backend_stap="yes"
+
+    # Workaround to avoid dtrace(1) producing a file with 'hidden' symbol
+    # visibility. Define STAP_SDT_V2 to produce 'default' symbol visibility
+    # instead. QEMU --enable-modules depends on this because the SystemTap
+    # semaphores are linked into the main binary and not the module's shared
+    # object.
+    QEMU_CFLAGS="$QEMU_CFLAGS -DSTAP_SDT_V2"
   fi
 fi
 

trace/meson.build

@@ -38,13 +38,13 @@ foreach dir : [ '.' ] + trace_events_subdirs
     trace_dtrace_h = custom_target(fmt.format('trace-dtrace', 'h'),
                                    output: fmt.format('trace-dtrace', 'h'),
                                    input: trace_dtrace,
-                                   command: [ 'dtrace', '-o', '@OUTPUT@', '-h', '-s', '@INPUT@' ])
+                                   command: [ 'dtrace', '-DSTAP_SDT_V2', '-o', '@OUTPUT@', '-h', '-s', '@INPUT@' ])
     trace_ss.add(trace_dtrace_h)
     if host_machine.system() != 'darwin'
       trace_dtrace_o = custom_target(fmt.format('trace-dtrace', 'o'),
                                      output: fmt.format('trace-dtrace', 'o'),
                                      input: trace_dtrace,
-                                     command: [ 'dtrace', '-o', '@OUTPUT@', '-G', '-s', '@INPUT@' ])
+                                     command: [ 'dtrace', '-DSTAP_SDT_V2', '-o', '@OUTPUT@', '-G', '-s', '@INPUT@' ])
       trace_ss.add(trace_dtrace_o)
     endif