On Mon, Jan 04, 2021 at 09:31:19PM +0100, Laurent Vivier wrote:
> On 11/11/2020 16:56, Stefan Hajnoczi wrote:
> > SystemTap's dtrace(1) prints the following warning when it encounters
> > long long arguments:
> >
> > Warning: /usr/bin/dtrace:trace/trace-dtrace-hw_virtio.dtrace:76: syntax
> > error near:
> > probe vhost_vdpa_dev_start
> >
> > Warning: Proceeding as if --no-pyparsing was given.
> >
> > Use the uint64_t and int64_t types, respectively. This works with all
> > host CPU 32- and 64-bit data models (ILP32, LP64, and LLP64) that QEMU
> > supports.
> >
> > Reported-by: Markus Armbruster <arm...@redhat.com>
> > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> > Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
> > Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
> > Message-id: 20201020094043.159935-1-stefa...@redhat.com
> > Suggested-by: Daniel P. Berrangé <berra...@redhat.com>
> > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> > ---
> > scripts/tracetool/format/d.py | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/scripts/tracetool/format/d.py b/scripts/tracetool/format/d.py
> > index 353722f89c..ebfb714200 100644
> > --- a/scripts/tracetool/format/d.py
> > +++ b/scripts/tracetool/format/d.py
> > @@ -57,6 +57,12 @@ def generate(events, backend, group):
> > # Avoid it by changing probe type to signed char *
> > beforehand.
> > if type_ == 'int8_t *':
> > type_ = 'signed char *'
> > +
> > + # SystemTap dtrace(1) emits a warning when long long is used
> > + type_ = type_.replace('unsigned long long', 'uint64_t')
> > + type_ = type_.replace('signed long long', 'int64_t')
> > + type_ = type_.replace('long long', 'int64_t')
> > +
> > if name in RESERVED_WORDS:
> > name += '_'
> > args.append(type_ + ' ' + name)
> >
>
> This patch fixes the warning with "d" format, but we have the same kind of
> problem with
> log-stap format:
>
> $ sudo stap -e 'probe begin{printf ("BEGIN")}' -I .
> parse error: invalid or missing conversion specifier
> saw: operator ',' at ./qemu-system-x86_64-log.stp:15118:101
> source: printf("%d@%d vhost_vdpa_set_log_base dev: %p base: 0x%x
> size: %llu
> refcnt: %d fd: %d log: %p\n", pid(), gettimeofday_ns(), dev, base, size,
> refcnt, fd, log)
>
> ^
>
> 1 parse error.
> WARNING: tapset "./qemu-system-x86_64-log.stp" has errors, and will be
> skipped
> BEGIN
>
> This happens because of the "%llu" in the format string.
>
> I'm wondering if we need to fix all the stap based format or simply replace
> the "unsigned
> long long" by "uint64_t" in hw/virtio/trace-events?
The problem isn't really the data type, but rather the format string.
systemtap format strings are not quite the same as C format strings.
So we need to re-write %llu into %lu I expect. We already do some
rewriting in log_stap.py but we obviously need a bit more.
Regards,
Daniel
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