[PATCH 0/2] trace: fix ability to use systemtap with qemu tools

[PATCH 0/2] trace: fix ability to use systemtap with qemu tools

[Daniel P. Berrangé]

Currently we're only generating .stp definitions for the system and
user emulators forgetting all about the tools which support tracing
too.

Daniel P. Berrangé (2):
  tracetool: remove redundant --target-type / --target-name args
  meson: generate .stp files for tools too

 docs/devel/tracing.rst |  3 +-
 meson.build            | 63 +++++++++++++++++++++++++++---------------
 scripts/tracetool.py   | 24 ++++------------
 3 files changed, 46 insertions(+), 44 deletions(-)

-- 
2.43.0

[PATCH 1/2] tracetool: remove redundant --target-type / --target-name args

[Daniel P. Berrangé]

The --target-type and --target-name args are used to construct
the default probe prefix if '--probe-prefix' is not given. The
meson.build will always pass '--probe-prefix', so the other args
are effectively redundant.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 docs/devel/tracing.rst |  3 +--
 meson.build            |  2 --
 scripts/tracetool.py   | 24 +++++-------------------
 3 files changed, 6 insertions(+), 23 deletions(-)

diff --git a/docs/devel/tracing.rst b/docs/devel/tracing.rst
index d288480db1..043bed7fd0 100644
--- a/docs/devel/tracing.rst
+++ b/docs/devel/tracing.rst
@@ -357,8 +357,7 @@ probes::
 
     scripts/tracetool.py --backends=dtrace --format=stap \
                          --binary path/to/qemu-binary \
-                         --target-type system \
-                         --target-name x86_64 \
+                         --probe-prefix qemu.system.x86_64 \
                          --group=all \
                          trace-events-all \
                          qemu.stp
diff --git a/meson.build b/meson.build
index 6c77d9687d..535f15da69 100644
--- a/meson.build
+++ b/meson.build
@@ -3934,8 +3934,6 @@ foreach target : target_dirs
                       command: [
                         tracetool, '--group=all', '--format=' + stp['fmt'],
                         '--binary=' + stp['bin'],
-                        '--target-name=' + target_name,
-                        '--target-type=' + target_type,
                         '--probe-prefix=qemu.' + target_type + '.' + target_name,
                         '@INPUT@', '@OUTPUT@'
                       ],
diff --git a/scripts/tracetool.py b/scripts/tracetool.py
index ab7653a5ce..5de9ce96d3 100755
--- a/scripts/tracetool.py
+++ b/scripts/tracetool.py
@@ -44,12 +44,9 @@ def error_opt(msg = None):
     --help                   This help message.
     --list-backends          Print list of available backends.
     --check-backends         Check if the given backend is valid.
-    --binary <path>          Full path to QEMU binary.
-    --target-type <type>     QEMU emulator target type ('system' or 'user').
-    --target-name <name>     QEMU emulator target name.
-    --group <name>           Name of the event group
-    --probe-prefix <prefix>  Prefix for dtrace probe names
-                             (default: qemu-<target-type>-<target-name>).\
+    --binary <path>          Full path to QEMU binary (required for 'stap' backend).
+    --group <name>           Name of the event group.
+    --probe-prefix <prefix>  Prefix for dtrace probe names (required for 'stap' backend).
 """ % {
             "script" : _SCRIPT,
             "backends" : backend_descr,
@@ -67,7 +64,7 @@ def main(args):
 
     long_opts = ["backends=", "format=", "help", "list-backends",
                  "check-backends", "group="]
-    long_opts += ["binary=", "target-type=", "target-name=", "probe-prefix="]
+    long_opts += ["binary=", "probe-prefix="]
 
     try:
         opts, args = getopt.getopt(args[1:], "", long_opts)
@@ -79,8 +76,6 @@ def main(args):
     arg_format = ""
     arg_group = None
     binary = None
-    target_type = None
-    target_name = None
     probe_prefix = None
     for opt, arg in opts:
         if opt == "--help":
@@ -102,10 +97,6 @@ def main(args):
 
         elif opt == "--binary":
             binary = arg
-        elif opt == '--target-type':
-            target_type = arg
-        elif opt == '--target-name':
-            target_name = arg
         elif opt == '--probe-prefix':
             probe_prefix = arg
 
@@ -127,13 +118,8 @@ def main(args):
     if arg_format == "stap":
         if binary is None:
             error_opt("--binary is required for SystemTAP tapset generator")
-        if probe_prefix is None and target_type is None:
-            error_opt("--target-type is required for SystemTAP tapset generator")
-        if probe_prefix is None and target_name is None:
-            error_opt("--target-name is required for SystemTAP tapset generator")
-
         if probe_prefix is None:
-            probe_prefix = ".".join(["qemu", target_type, target_name])
+            error_opt("--probe-prefix is required for SystemTAP tapset generator")
 
     if len(args) < 2:
         error_opt("missing trace-events and output filepaths")
-- 
2.43.0

Re: [PATCH 1/2] tracetool: remove redundant --target-type / --target-name args

[John Snow]

On Mon, Jan 8, 2024 at 12:14 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> The --target-type and --target-name args are used to construct
> the default probe prefix if '--probe-prefix' is not given. The
> meson.build will always pass '--probe-prefix', so the other args
> are effectively redundant.
>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Fine by me, provided there's no reason anyone is calling tracetool
manually for some reason I haven't thought about. I assume we'll hear
about it if so...

Python looks fine, of course.

Reviewed-by: John Snow <jsnow@redhat.com>

(Happy New Year!)

> ---
>  docs/devel/tracing.rst |  3 +--
>  meson.build            |  2 --
>  scripts/tracetool.py   | 24 +++++-------------------
>  3 files changed, 6 insertions(+), 23 deletions(-)
>
> diff --git a/docs/devel/tracing.rst b/docs/devel/tracing.rst
> index d288480db1..043bed7fd0 100644
> --- a/docs/devel/tracing.rst
> +++ b/docs/devel/tracing.rst
> @@ -357,8 +357,7 @@ probes::
>
>      scripts/tracetool.py --backends=dtrace --format=stap \
>                           --binary path/to/qemu-binary \
> -                         --target-type system \
> -                         --target-name x86_64 \
> +                         --probe-prefix qemu.system.x86_64 \
>                           --group=all \
>                           trace-events-all \
>                           qemu.stp
> diff --git a/meson.build b/meson.build
> index 6c77d9687d..535f15da69 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -3934,8 +3934,6 @@ foreach target : target_dirs
>                        command: [
>                          tracetool, '--group=all', '--format=' + stp['fmt'],
>                          '--binary=' + stp['bin'],
> -                        '--target-name=' + target_name,
> -                        '--target-type=' + target_type,
>                          '--probe-prefix=qemu.' + target_type + '.' + target_name,
>                          '@INPUT@', '@OUTPUT@'
>                        ],
> diff --git a/scripts/tracetool.py b/scripts/tracetool.py
> index ab7653a5ce..5de9ce96d3 100755
> --- a/scripts/tracetool.py
> +++ b/scripts/tracetool.py
> @@ -44,12 +44,9 @@ def error_opt(msg = None):
>      --help                   This help message.
>      --list-backends          Print list of available backends.
>      --check-backends         Check if the given backend is valid.
> -    --binary <path>          Full path to QEMU binary.
> -    --target-type <type>     QEMU emulator target type ('system' or 'user').
> -    --target-name <name>     QEMU emulator target name.
> -    --group <name>           Name of the event group
> -    --probe-prefix <prefix>  Prefix for dtrace probe names
> -                             (default: qemu-<target-type>-<target-name>).\
> +    --binary <path>          Full path to QEMU binary (required for 'stap' backend).
> +    --group <name>           Name of the event group.
> +    --probe-prefix <prefix>  Prefix for dtrace probe names (required for 'stap' backend).
>  """ % {
>              "script" : _SCRIPT,
>              "backends" : backend_descr,
> @@ -67,7 +64,7 @@ def main(args):
>
>      long_opts = ["backends=", "format=", "help", "list-backends",
>                   "check-backends", "group="]
> -    long_opts += ["binary=", "target-type=", "target-name=", "probe-prefix="]
> +    long_opts += ["binary=", "probe-prefix="]
>
>      try:
>          opts, args = getopt.getopt(args[1:], "", long_opts)
> @@ -79,8 +76,6 @@ def main(args):
>      arg_format = ""
>      arg_group = None
>      binary = None
> -    target_type = None
> -    target_name = None
>      probe_prefix = None
>      for opt, arg in opts:
>          if opt == "--help":
> @@ -102,10 +97,6 @@ def main(args):
>
>          elif opt == "--binary":
>              binary = arg
> -        elif opt == '--target-type':
> -            target_type = arg
> -        elif opt == '--target-name':
> -            target_name = arg
>          elif opt == '--probe-prefix':
>              probe_prefix = arg
>
> @@ -127,13 +118,8 @@ def main(args):
>      if arg_format == "stap":
>          if binary is None:
>              error_opt("--binary is required for SystemTAP tapset generator")
> -        if probe_prefix is None and target_type is None:
> -            error_opt("--target-type is required for SystemTAP tapset generator")
> -        if probe_prefix is None and target_name is None:
> -            error_opt("--target-name is required for SystemTAP tapset generator")
> -
>          if probe_prefix is None:
> -            probe_prefix = ".".join(["qemu", target_type, target_name])
> +            error_opt("--probe-prefix is required for SystemTAP tapset generator")
>
>      if len(args) < 2:
>          error_opt("missing trace-events and output filepaths")
> --
> 2.43.0
>

Re: [PATCH 1/2] tracetool: remove redundant --target-type / --target-name args

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 734 bytes --]

On Mon, Jan 08, 2024 at 04:50:40PM -0500, John Snow wrote:
> On Mon, Jan 8, 2024 at 12:14 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
> >
> > The --target-type and --target-name args are used to construct
> > the default probe prefix if '--probe-prefix' is not given. The
> > meson.build will always pass '--probe-prefix', so the other args
> > are effectively redundant.
> >
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> 
> Fine by me, provided there's no reason anyone is calling tracetool
> manually for some reason I haven't thought about. I assume we'll hear
> about it if so...

That's okay. tracetool.py is internal to QEMU so we're free to change
the command-line options.

Stefan

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH 2/2] meson: generate .stp files for tools too

[Daniel P. Berrangé]

The qemu-img, qemu-io, qemu-nbd, qemu-storage-daemon tools all have
support for systemtap tracing built-in, so should be given corresponding
.stp files to define their probes.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 meson.build | 61 +++++++++++++++++++++++++++++++++++------------------
 1 file changed, 40 insertions(+), 21 deletions(-)

diff --git a/meson.build b/meson.build
index 535f15da69..4db6907a20 100644
--- a/meson.build
+++ b/meson.build
@@ -3752,6 +3752,7 @@ if targetos == 'darwin'
   entitlement = find_program('scripts/entitlement.sh')
 endif
 
+traceable = []
 emulators = {}
 foreach target : target_dirs
   config_target = config_target_mak[target]
@@ -3919,27 +3920,11 @@ foreach target : target_dirs
       emulators += {exe['name']: emulator}
     endif
 
-    if stap.found()
-      foreach stp: [
-        {'ext': '.stp-build', 'fmt': 'stap', 'bin': meson.current_build_dir() / exe['name'], 'install': false},
-        {'ext': '.stp', 'fmt': 'stap', 'bin': get_option('prefix') / get_option('bindir') / exe['name'], 'install': true},
-        {'ext': '-simpletrace.stp', 'fmt': 'simpletrace-stap', 'bin': '', 'install': true},
-        {'ext': '-log.stp', 'fmt': 'log-stap', 'bin': '', 'install': true},
-      ]
-        custom_target(exe['name'] + stp['ext'],
-                      input: trace_events_all,
-                      output: exe['name'] + stp['ext'],
-                      install: stp['install'],
-                      install_dir: get_option('datadir') / 'systemtap/tapset',
-                      command: [
-                        tracetool, '--group=all', '--format=' + stp['fmt'],
-                        '--binary=' + stp['bin'],
-                        '--probe-prefix=qemu.' + target_type + '.' + target_name,
-                        '@INPUT@', '@OUTPUT@'
-                      ],
-                      depend_files: tracetool_depends)
-      endforeach
-    endif
+    traceable += [{
+      'exe': exe['name'],
+      'probe-prefix': 'qemu.' + target_type + '.' + target_name,
+    }]
+
   endforeach
 endforeach
 
@@ -3974,6 +3959,14 @@ if have_tools
                install: true)
 
   subdir('storage-daemon')
+
+  foreach exe: [ 'qemu-img', 'qemu-io', 'qemu-nbd', 'qemu-storage-daemon']
+    traceable += [{
+      'exe': exe,
+      'probe-prefix': 'qemu.' + exe.substring(5).replace('-', '_')
+    }]
+  endforeach
+
   subdir('contrib/rdmacm-mux')
   subdir('contrib/elf2dmp')
 
@@ -4006,6 +3999,32 @@ if have_tools
   endif
 endif
 
+if stap.found()
+  foreach t: traceable
+    foreach stp: [
+      {'ext': '.stp-build', 'fmt': 'stap', 'bin': meson.current_build_dir() / t['exe'], 'install': false},
+      {'ext': '.stp', 'fmt': 'stap', 'bin': get_option('prefix') / get_option('bindir') / t['exe'], 'install': true},
+      {'ext': '-simpletrace.stp', 'fmt': 'simpletrace-stap', 'bin': '', 'install': true},
+      {'ext': '-log.stp', 'fmt': 'log-stap', 'bin': '', 'install': true},
+    ]
+      cmd = [
+        tracetool, '--group=all', '--format=' + stp['fmt'],
+        '--binary=' + stp['bin'],
+        '--probe-prefix=' + t['probe-prefix'],
+        '@INPUT@', '@OUTPUT@'
+      ]
+
+      custom_target(t['exe'] + stp['ext'],
+                    input: trace_events_all,
+                    output: t['exe'] + stp['ext'],
+                    install: stp['install'],
+                    install_dir: get_option('datadir') / 'systemtap/tapset',
+                    command: cmd,
+                    depend_files: tracetool_depends)
+    endforeach
+  endforeach
+endif
+
 subdir('scripts')
 subdir('tools')
 subdir('pc-bios')
-- 
2.43.0

Re: [PATCH 2/2] meson: generate .stp files for tools too

[Eric Blake]

On Mon, Jan 08, 2024 at 05:13:56PM +0000, Daniel P. Berrangé wrote:
> The qemu-img, qemu-io, qemu-nbd, qemu-storage-daemon tools all have
> support for systemtap tracing built-in, so should be given corresponding
> .stp files to define their probes.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  meson.build | 61 +++++++++++++++++++++++++++++++++++------------------
>  1 file changed, 40 insertions(+), 21 deletions(-)

I'm less familiar with writing meson rules, but I can follow how you
refactored the stap.found() logic to be shared among two different
groups of traceable binaries, with the obvious difference being the
generation of command:[] in a way that uses the correct prefixes per
tracable item.

And since I hit the problem of not being able to see trace output via
qemu-trace-stap on qemu-io, this makes sense.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization:  qemu.org | libguestfs.org

Re: [PATCH 0/2] trace: fix ability to use systemtap with qemu tools

[Daniel P. Berrangé]

Ping: Stefan, are you OK with picking up these trace patches
for merge ?

On Mon, Jan 08, 2024 at 05:13:54PM +0000, Daniel P. Berrangé wrote:
> Currently we're only generating .stp definitions for the system and
> user emulators forgetting all about the tools which support tracing
> too.
> 
> Daniel P. Berrangé (2):
>   tracetool: remove redundant --target-type / --target-name args
>   meson: generate .stp files for tools too
> 
>  docs/devel/tracing.rst |  3 +-
>  meson.build            | 63 +++++++++++++++++++++++++++---------------
>  scripts/tracetool.py   | 24 ++++------------
>  3 files changed, 46 insertions(+), 44 deletions(-)


> 
> -- 
> 2.43.0
> 

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

Re: [PATCH 0/2] trace: fix ability to use systemtap with qemu tools

[Daniel P. Berrangé]

Ping again for these patches to get into this release.

On Fri, Feb 16, 2024 at 01:09:33PM +0000, Daniel P. Berrangé wrote:
> Ping: Stefan, are you OK with picking up these trace patches
> for merge ?
> 
> On Mon, Jan 08, 2024 at 05:13:54PM +0000, Daniel P. Berrangé wrote:
> > Currently we're only generating .stp definitions for the system and
> > user emulators forgetting all about the tools which support tracing
> > too.
> > 
> > Daniel P. Berrangé (2):
> >   tracetool: remove redundant --target-type / --target-name args
> >   meson: generate .stp files for tools too
> > 
> >  docs/devel/tracing.rst |  3 +-
> >  meson.build            | 63 +++++++++++++++++++++++++++---------------
> >  scripts/tracetool.py   | 24 ++++------------
> >  3 files changed, 46 insertions(+), 44 deletions(-)

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

Re: [PATCH 0/2] trace: fix ability to use systemtap with qemu tools

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 320 bytes --]

On Tue, Mar 12, 2024 at 11:34:21AM +0000, Daniel P. Berrangé wrote:
> Ping again for these patches to get into this release.
> 
> On Fri, Feb 16, 2024 at 01:09:33PM +0000, Daniel P. Berrangé wrote:
> > Ping: Stefan, are you OK with picking up these trace patches
> > for merge ?

Sorry, I missed them.

Stefan

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH 0/2] trace: fix ability to use systemtap with qemu tools

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 706 bytes --]

On Mon, Jan 08, 2024 at 05:13:54PM +0000, Daniel P. Berrangé wrote:
> Currently we're only generating .stp definitions for the system and
> user emulators forgetting all about the tools which support tracing
> too.
> 
> Daniel P. Berrangé (2):
>   tracetool: remove redundant --target-type / --target-name args
>   meson: generate .stp files for tools too
> 
>  docs/devel/tracing.rst |  3 +-
>  meson.build            | 63 +++++++++++++++++++++++++++---------------
>  scripts/tracetool.py   | 24 ++++------------
>  3 files changed, 46 insertions(+), 44 deletions(-)
> 
> -- 
> 2.43.0
> 

Thanks, applied to my tracing tree:
https://gitlab.com/stefanha/qemu/commits/tracing

Stefan

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]