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[PATCH v1 07/11] perf probe: Move elfutils support check to libdw check

Ian Rogers posted 11 patches 2 months ago
There is a newer version of this series
[PATCH v1 07/11] perf probe: Move elfutils support check to libdw check
Posted by Ian Rogers 2 months ago 
The test _ELFUTILS_PREREQ(0, 142) is false for elfutils before
2009-06-13, but that is 15 years ago and very unlikely. Add a test to
test-libdw.c and assume the libdw version is at least 0.142 to
simplify the build logic.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/build/feature/test-libdw.c | 10 +++++++++-
 tools/perf/util/probe-finder.c   |  2 --
 tools/perf/util/probe-finder.h   |  2 --
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/tools/build/feature/test-libdw.c b/tools/build/feature/test-libdw.c
index 71c6f8e3b0ee..2fb59479ab77 100644
--- a/tools/build/feature/test-libdw.c
+++ b/tools/build/feature/test-libdw.c
@@ -41,8 +41,16 @@ int test_libdw_getcfi(void)
 	return dwarf_getcfi(dwarf) == NULL;
 }
 
+int test_elfutils(void)
+{
+	Dwarf_CFI *cfi = NULL;
+
+	dwarf_cfi_end(cfi);
+	return 0;
+}
+
 int main(void)
 {
 	return test_libdw() + test_libdw_unwind() + test_libdw_getlocations() +
-	       test_libdw_getcfi();
+	       test_libdw_getcfi() + test_elfutils();
 }
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 78f34fa0c391..7434b38596b9 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1379,10 +1379,8 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
 	if (ret >= 0 && tf.pf.skip_empty_arg)
 		ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
 
-#if _ELFUTILS_PREREQ(0, 142)
 	dwarf_cfi_end(tf.pf.cfi_eh);
 	dwarf_cfi_end(tf.pf.cfi_dbg);
-#endif
 
 	if (ret < 0 || tf.ntevs == 0) {
 		for (i = 0; i < tf.ntevs; i++)
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 3add5ff516e1..f0149d72310c 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -63,12 +63,10 @@ struct probe_finder {
 	struct intlist		*lcache;	/* Line cache for lazy match */
 
 	/* For variable searching */
-#if _ELFUTILS_PREREQ(0, 142)
 	/* Call Frame Information from .eh_frame */
 	Dwarf_CFI		*cfi_eh;
 	/* Call Frame Information from .debug_frame */
 	Dwarf_CFI		*cfi_dbg;
-#endif
 	Dwarf_Op		*fb_ops;	/* Frame base attribute */
 	unsigned int		machine;	/* Target machine arch */
 	struct perf_probe_arg	*pvar;		/* Current target variable */
-- 
2.46.0.792.g87dc391469-goog
Re: [PATCH v1 07/11] perf probe: Move elfutils support check to libdw check
Posted by Namhyung Kim 2 months ago 
On Tue, Sep 24, 2024 at 09:04:14AM -0700, Ian Rogers wrote:
> The test _ELFUTILS_PREREQ(0, 142) is false for elfutils before
> 2009-06-13, but that is 15 years ago and very unlikely. Add a test to
> test-libdw.c and assume the libdw version is at least 0.142 to
> simplify the build logic.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/build/feature/test-libdw.c | 10 +++++++++-
>  tools/perf/util/probe-finder.c   |  2 --
>  tools/perf/util/probe-finder.h   |  2 --
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/build/feature/test-libdw.c b/tools/build/feature/test-libdw.c
> index 71c6f8e3b0ee..2fb59479ab77 100644
> --- a/tools/build/feature/test-libdw.c
> +++ b/tools/build/feature/test-libdw.c
> @@ -41,8 +41,16 @@ int test_libdw_getcfi(void)
>  	return dwarf_getcfi(dwarf) == NULL;
>  }
>  
> +int test_elfutils(void)
> +{
> +	Dwarf_CFI *cfi = NULL;
> +
> +	dwarf_cfi_end(cfi);
> +	return 0;
> +}

I think it's the same as test_libdw_getcfi() and let's get rid of it.

Thanks,
Namhyung

> +
>  int main(void)
>  {
>  	return test_libdw() + test_libdw_unwind() + test_libdw_getlocations() +
> -	       test_libdw_getcfi();
> +	       test_libdw_getcfi() + test_elfutils();
>  }
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 78f34fa0c391..7434b38596b9 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -1379,10 +1379,8 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
>  	if (ret >= 0 && tf.pf.skip_empty_arg)
>  		ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
>  
> -#if _ELFUTILS_PREREQ(0, 142)
>  	dwarf_cfi_end(tf.pf.cfi_eh);
>  	dwarf_cfi_end(tf.pf.cfi_dbg);
> -#endif
>  
>  	if (ret < 0 || tf.ntevs == 0) {
>  		for (i = 0; i < tf.ntevs; i++)
> diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
> index 3add5ff516e1..f0149d72310c 100644
> --- a/tools/perf/util/probe-finder.h
> +++ b/tools/perf/util/probe-finder.h
> @@ -63,12 +63,10 @@ struct probe_finder {
>  	struct intlist		*lcache;	/* Line cache for lazy match */
>  
>  	/* For variable searching */
> -#if _ELFUTILS_PREREQ(0, 142)
>  	/* Call Frame Information from .eh_frame */
>  	Dwarf_CFI		*cfi_eh;
>  	/* Call Frame Information from .debug_frame */
>  	Dwarf_CFI		*cfi_dbg;
> -#endif
>  	Dwarf_Op		*fb_ops;	/* Frame base attribute */
>  	unsigned int		machine;	/* Target machine arch */
>  	struct perf_probe_arg	*pvar;		/* Current target variable */
> -- 
> 2.46.0.792.g87dc391469-goog
>
Re: [PATCH v1 07/11] perf probe: Move elfutils support check to libdw check
Posted by Ian Rogers 2 months ago 
On Wed, Sep 25, 2024 at 5:30 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Tue, Sep 24, 2024 at 09:04:14AM -0700, Ian Rogers wrote:
> > The test _ELFUTILS_PREREQ(0, 142) is false for elfutils before
> > 2009-06-13, but that is 15 years ago and very unlikely. Add a test to
> > test-libdw.c and assume the libdw version is at least 0.142 to
> > simplify the build logic.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/build/feature/test-libdw.c | 10 +++++++++-
> >  tools/perf/util/probe-finder.c   |  2 --
> >  tools/perf/util/probe-finder.h   |  2 --
> >  3 files changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/build/feature/test-libdw.c b/tools/build/feature/test-libdw.c
> > index 71c6f8e3b0ee..2fb59479ab77 100644
> > --- a/tools/build/feature/test-libdw.c
> > +++ b/tools/build/feature/test-libdw.c
> > @@ -41,8 +41,16 @@ int test_libdw_getcfi(void)
> >       return dwarf_getcfi(dwarf) == NULL;
> >  }
> >
> > +int test_elfutils(void)
> > +{
> > +     Dwarf_CFI *cfi = NULL;
> > +
> > +     dwarf_cfi_end(cfi);
> > +     return 0;
> > +}
>
> I think it's the same as test_libdw_getcfi() and let's get rid of it.

The point of doing the change this way, and I think what's being
ignored, is that I am trying to simply replace an #if with a clearly
equivalent feature test - clearly equivalent as the #if guards use of
dwarf_cfi_end in the code. Merging test_elfutils with
test_libdw_getcfi is another cognitive step and I think it is fine as
follow up cleanup. Combining that step with the change here fails the
minimal meaningful change and tbh I think this is just bike shedding.

Thanks,
Ian

> Thanks,
> Namhyung
>
> > +
> >  int main(void)
> >  {
> >       return test_libdw() + test_libdw_unwind() + test_libdw_getlocations() +
> > -            test_libdw_getcfi();
> > +            test_libdw_getcfi() + test_elfutils();
> >  }
> > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> > index 78f34fa0c391..7434b38596b9 100644
> > --- a/tools/perf/util/probe-finder.c
> > +++ b/tools/perf/util/probe-finder.c
> > @@ -1379,10 +1379,8 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
> >       if (ret >= 0 && tf.pf.skip_empty_arg)
> >               ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
> >
> > -#if _ELFUTILS_PREREQ(0, 142)
> >       dwarf_cfi_end(tf.pf.cfi_eh);
> >       dwarf_cfi_end(tf.pf.cfi_dbg);
> > -#endif
> >
> >       if (ret < 0 || tf.ntevs == 0) {
> >               for (i = 0; i < tf.ntevs; i++)
> > diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
> > index 3add5ff516e1..f0149d72310c 100644
> > --- a/tools/perf/util/probe-finder.h
> > +++ b/tools/perf/util/probe-finder.h
> > @@ -63,12 +63,10 @@ struct probe_finder {
> >       struct intlist          *lcache;        /* Line cache for lazy match */
> >
> >       /* For variable searching */
> > -#if _ELFUTILS_PREREQ(0, 142)
> >       /* Call Frame Information from .eh_frame */
> >       Dwarf_CFI               *cfi_eh;
> >       /* Call Frame Information from .debug_frame */
> >       Dwarf_CFI               *cfi_dbg;
> > -#endif
> >       Dwarf_Op                *fb_ops;        /* Frame base attribute */
> >       unsigned int            machine;        /* Target machine arch */
> >       struct perf_probe_arg   *pvar;          /* Current target variable */
> > --
> > 2.46.0.792.g87dc391469-goog
> >
Re: [PATCH v1 07/11] perf probe: Move elfutils support check to libdw check
Posted by Namhyung Kim 2 months ago 
On Thu, Sep 26, 2024 at 08:08:22AM -0700, Ian Rogers wrote:
> On Wed, Sep 25, 2024 at 5:30 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > On Tue, Sep 24, 2024 at 09:04:14AM -0700, Ian Rogers wrote:
> > > The test _ELFUTILS_PREREQ(0, 142) is false for elfutils before
> > > 2009-06-13, but that is 15 years ago and very unlikely. Add a test to
> > > test-libdw.c and assume the libdw version is at least 0.142 to
> > > simplify the build logic.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/build/feature/test-libdw.c | 10 +++++++++-
> > >  tools/perf/util/probe-finder.c   |  2 --
> > >  tools/perf/util/probe-finder.h   |  2 --
> > >  3 files changed, 9 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/tools/build/feature/test-libdw.c b/tools/build/feature/test-libdw.c
> > > index 71c6f8e3b0ee..2fb59479ab77 100644
> > > --- a/tools/build/feature/test-libdw.c
> > > +++ b/tools/build/feature/test-libdw.c
> > > @@ -41,8 +41,16 @@ int test_libdw_getcfi(void)
> > >       return dwarf_getcfi(dwarf) == NULL;
> > >  }
> > >
> > > +int test_elfutils(void)
> > > +{
> > > +     Dwarf_CFI *cfi = NULL;
> > > +
> > > +     dwarf_cfi_end(cfi);
> > > +     return 0;
> > > +}
> >
> > I think it's the same as test_libdw_getcfi() and let's get rid of it.
> 
> The point of doing the change this way, and I think what's being
> ignored, is that I am trying to simply replace an #if with a clearly
> equivalent feature test - clearly equivalent as the #if guards use of
> dwarf_cfi_end in the code. Merging test_elfutils with
> test_libdw_getcfi is another cognitive step and I think it is fine as
> follow up cleanup. Combining that step with the change here fails the
> minimal meaningful change and tbh I think this is just bike shedding.

Ok, I think it's ok to have a separate commit to combine equivalent
tests if you really want to.  What I want in the end is not to have
unnecessary or duplicate code.

In order to have a clearly equivalent feature test, I think you can add

  #if !_ELFUTILS_PREREQ(0, 142)
  #error "elfutils version is too old"
  #endif

Thanks,
Namhyung

> >
> > > +
> > >  int main(void)
> > >  {
> > >       return test_libdw() + test_libdw_unwind() + test_libdw_getlocations() +
> > > -            test_libdw_getcfi();
> > > +            test_libdw_getcfi() + test_elfutils();
> > >  }
> > > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> > > index 78f34fa0c391..7434b38596b9 100644
> > > --- a/tools/perf/util/probe-finder.c
> > > +++ b/tools/perf/util/probe-finder.c
> > > @@ -1379,10 +1379,8 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
> > >       if (ret >= 0 && tf.pf.skip_empty_arg)
> > >               ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
> > >
> > > -#if _ELFUTILS_PREREQ(0, 142)
> > >       dwarf_cfi_end(tf.pf.cfi_eh);
> > >       dwarf_cfi_end(tf.pf.cfi_dbg);
> > > -#endif
> > >
> > >       if (ret < 0 || tf.ntevs == 0) {
> > >               for (i = 0; i < tf.ntevs; i++)
> > > diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
> > > index 3add5ff516e1..f0149d72310c 100644
> > > --- a/tools/perf/util/probe-finder.h
> > > +++ b/tools/perf/util/probe-finder.h
> > > @@ -63,12 +63,10 @@ struct probe_finder {
> > >       struct intlist          *lcache;        /* Line cache for lazy match */
> > >
> > >       /* For variable searching */
> > > -#if _ELFUTILS_PREREQ(0, 142)
> > >       /* Call Frame Information from .eh_frame */
> > >       Dwarf_CFI               *cfi_eh;
> > >       /* Call Frame Information from .debug_frame */
> > >       Dwarf_CFI               *cfi_dbg;
> > > -#endif
> > >       Dwarf_Op                *fb_ops;        /* Frame base attribute */
> > >       unsigned int            machine;        /* Target machine arch */
> > >       struct perf_probe_arg   *pvar;          /* Current target variable */
> > > --
> > > 2.46.0.792.g87dc391469-goog
> > >

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