[dwarves,v4,0/4] Emit global variables in BTF

Message

Stephen Brennan Oct. 4, 2024, 5:26 p.m. UTC

Hi all,

This is v4 of the series which adds global variables to pahole's generated BTF.

Since v3:

1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
2. Consistently start shndx loops at 1, and use size_t.
3. Since patch 1 of v3 was already applied, I dropped it out of this series.

v3: https://lore.kernel.org/dwarves/[e-mail]/
v2: https://lore.kernel.org/dwarves/[e-mail]/
v1: https://lore.kernel.org/dwarves/[e-mail]/

Thanks everyone for your review, tests, and consideration!
Stephen

Stephen Brennan (4):
  btf_encoder: stop indexing symbols for VARs
  btf_encoder: explicitly check addr/size for u32 overflow
  btf_encoder: allow encoding VARs from many sections
  pahole: add global_var BTF feature

 btf_encoder.c      | 340 +++++++++++++++++++++------------------------
 btf_encoder.h      |   1 +
 dwarves.h          |   1 +
 man-pages/pahole.1 |   7 +-
 pahole.c           |   3 +-
 5 files changed, 167 insertions(+), 185 deletions(-)

Comments

Arnaldo Carvalho de Melo Oct. 4, 2024, 8:58 p.m. UTC | #1

On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
> Hi all,
> 
> This is v4 of the series which adds global variables to pahole's generated BTF.
> 
> Since v3:
> 
> 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
> 2. Consistently start shndx loops at 1, and use size_t.
> 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
> 
> v3: https://lore.kernel.org/dwarves/[e-mail]/
> v2: https://lore.kernel.org/dwarves/[e-mail]/
> v1: https://lore.kernel.org/dwarves/[e-mail]/
> 
> Thanks everyone for your review, tests, and consideration!

Looks ok, I run the existing regression tests:

acme@x1:~/git/pahole$ tests/tests 
  1: Validation of BTF encoding of functions; this may take some time: Ok
  2: Pretty printing of files using DWARF type information: Ok
  3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
/home/acme/git/pahole
acme@x1:~/git/pahole$

And now I'm building a kernel with clang + Thin LTO + Rust enabled in
the kernel to test other fixes I have merged and doing that with your
patch series.

Its all in the next branch and will move to master later today or
tomorrow when I finish the clang+LTO+Rust tests.

- Arnaldo

> Stephen
> 
> Stephen Brennan (4):
>   btf_encoder: stop indexing symbols for VARs
>   btf_encoder: explicitly check addr/size for u32 overflow
>   btf_encoder: allow encoding VARs from many sections
>   pahole: add global_var BTF feature
> 
>  btf_encoder.c      | 340 +++++++++++++++++++++------------------------
>  btf_encoder.h      |   1 +
>  dwarves.h          |   1 +
>  man-pages/pahole.1 |   7 +-
>  pahole.c           |   3 +-
>  5 files changed, 167 insertions(+), 185 deletions(-)
> 
> -- 
> 2.43.5

Arnaldo Carvalho de Melo Oct. 4, 2024, 9:01 p.m. UTC | #2

On Fri, Oct 04, 2024 at 05:58:48PM -0300, Arnaldo Carvalho de Melo wrote:
> On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
> > Hi all,
> > 
> > This is v4 of the series which adds global variables to pahole's generated BTF.
> > 
> > Since v3:
> > 
> > 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
> > 2. Consistently start shndx loops at 1, and use size_t.
> > 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
> > 
> > v3: https://lore.kernel.org/dwarves/[e-mail]/
> > v2: https://lore.kernel.org/dwarves/[e-mail]/
> > v1: https://lore.kernel.org/dwarves/[e-mail]/
> > 
> > Thanks everyone for your review, tests, and consideration!
> 
> Looks ok, I run the existing regression tests:
> 
> acme@x1:~/git/pahole$ tests/tests 
>   1: Validation of BTF encoding of functions; this may take some time: Ok
>   2: Pretty printing of files using DWARF type information: Ok
>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
> /home/acme/git/pahole
> acme@x1:~/git/pahole$
> 
> And now I'm building a kernel with clang + Thin LTO + Rust enabled in
> the kernel to test other fixes I have merged and doing that with your
> patch series.
> 
> Its all in the next branch and will move to master later today or
> tomorrow when I finish the clang+LTO+Rust tests.

Ah, please consider looking at the test/ scripts and try to write a
simple test that will encode global vars from the running kernel and
then use bpftool to dump them and look for some of the well known kernel
global variables being encoded to match expectations, so that we have
this feature continuously tested vai tests/tests.

If now the increase in size due to global vars is of N%, please consider
checking if that is off by some unreasonable margin, etc.

Thanks!

- Arnaldo

Andrii Nakryiko Oct. 7, 2024, 5:12 p.m. UTC | #3

On Fri, Oct 4, 2024 at 2:21 PM Arnaldo Carvalho de Melo <[e-mail]> wrote:
>
> On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
> > Hi all,
> >
> > This is v4 of the series which adds global variables to pahole's generated BTF.
> >
> > Since v3:
> >
> > 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
> > 2. Consistently start shndx loops at 1, and use size_t.
> > 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
> >
> > v3: https://lore.kernel.org/dwarves/[e-mail]/
> > v2: https://lore.kernel.org/dwarves/[e-mail]/
> > v1: https://lore.kernel.org/dwarves/[e-mail]/
> >
> > Thanks everyone for your review, tests, and consideration!
>
> Looks ok, I run the existing regression tests:
>
> acme@x1:~/git/pahole$ tests/tests
>   1: Validation of BTF encoding of functions; this may take some time: Ok
>   2: Pretty printing of files using DWARF type information: Ok
>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
> /home/acme/git/pahole
> acme@x1:~/git/pahole$
>
> And now I'm building a kernel with clang + Thin LTO + Rust enabled in
> the kernel to test other fixes I have merged and doing that with your
> patch series.
>
> Its all in the next branch and will move to master later today or
> tomorrow when I finish the clang+LTO+Rust tests.

pahole-staging testing in libbpf CI started failing recently, can you
please double-check and see if this was caused by these changes? They
seem to be related to encoding BTF for per-CPU global variables, so
might be relevant ([0] for full run logs)

  #33      btf_dump:FAIL
  libbpf: extern (var ksym) 'bpf_prog_active': not found in kernel BTF
  libbpf: failed to load object 'kfunc_call_test_subprog'
  libbpf: failed to load BPF skeleton 'kfunc_call_test_subprog': -22
  test_subprog:FAIL:skel unexpected error: -22
  #126/17  kfunc_call/subprog:FAIL
  test_subprog_lskel:FAIL:skel unexpected error: -2
  #126/18  kfunc_call/subprog_lskel:FAIL
  #126     kfunc_call:FAIL
  test_ksyms_module_lskel:FAIL:test_ksyms_module_lskel__open_and_load
unexpected error: -2
  #135/1   ksyms_module/lskel:FAIL
  libbpf: extern (var ksym) 'bpf_testmod_ksym_percpu': not found in kernel BTF
  libbpf: failed to load object 'test_ksyms_module'
  libbpf: failed to load BPF skeleton 'test_ksyms_module': -22
  test_ksyms_module_libbpf:FAIL:test_ksyms_module__open unexpected error: -22
  #135/2   ksyms_module/libbpf:FAIL


  [0] https://github.com/libbpf/libbpf/actions/runs/11204199648/job/31142297399#step:4:12480

>
> - Arnaldo
>
> > Stephen
> >
> > Stephen Brennan (4):
> >   btf_encoder: stop indexing symbols for VARs
> >   btf_encoder: explicitly check addr/size for u32 overflow
> >   btf_encoder: allow encoding VARs from many sections
> >   pahole: add global_var BTF feature
> >
> >  btf_encoder.c      | 340 +++++++++++++++++++++------------------------
> >  btf_encoder.h      |   1 +
> >  dwarves.h          |   1 +
> >  man-pages/pahole.1 |   7 +-
> >  pahole.c           |   3 +-
> >  5 files changed, 167 insertions(+), 185 deletions(-)
> >
> > --
> > 2.43.5
>

Stephen Brennan Oct. 7, 2024, 5:24 p.m. UTC | #4

Andrii Nakryiko <[e-mail]> writes:
> On Fri, Oct 4, 2024 at 2:21 PM Arnaldo Carvalho de Melo <[e-mail]> wrote:
>>
>> On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
>> > Hi all,
>> >
>> > This is v4 of the series which adds global variables to pahole's generated BTF.
>> >
>> > Since v3:
>> >
>> > 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
>> > 2. Consistently start shndx loops at 1, and use size_t.
>> > 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
>> >
>> > v3: https://lore.kernel.org/dwarves/[e-mail]/
>> > v2: https://lore.kernel.org/dwarves/[e-mail]/
>> > v1: https://lore.kernel.org/dwarves/[e-mail]/
>> >
>> > Thanks everyone for your review, tests, and consideration!
>>
>> Looks ok, I run the existing regression tests:
>>
>> acme@x1:~/git/pahole$ tests/tests
>>   1: Validation of BTF encoding of functions; this may take some time: Ok
>>   2: Pretty printing of files using DWARF type information: Ok
>>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
>> /home/acme/git/pahole
>> acme@x1:~/git/pahole$
>>
>> And now I'm building a kernel with clang + Thin LTO + Rust enabled in
>> the kernel to test other fixes I have merged and doing that with your
>> patch series.
>>
>> Its all in the next branch and will move to master later today or
>> tomorrow when I finish the clang+LTO+Rust tests.
>
> pahole-staging testing in libbpf CI started failing recently, can you
> please double-check and see if this was caused by these changes? They
> seem to be related to encoding BTF for per-CPU global variables, so
> might be relevant ([0] for full run logs)
>
>   #33      btf_dump:FAIL
>   libbpf: extern (var ksym) 'bpf_prog_active': not found in kernel BTF
>   libbpf: failed to load object 'kfunc_call_test_subprog'
>   libbpf: failed to load BPF skeleton 'kfunc_call_test_subprog': -22
>   test_subprog:FAIL:skel unexpected error: -22
>   #126/17  kfunc_call/subprog:FAIL
>   test_subprog_lskel:FAIL:skel unexpected error: -2
>   #126/18  kfunc_call/subprog_lskel:FAIL
>   #126     kfunc_call:FAIL
>   test_ksyms_module_lskel:FAIL:test_ksyms_module_lskel__open_and_load
> unexpected error: -2
>   #135/1   ksyms_module/lskel:FAIL
>   libbpf: extern (var ksym) 'bpf_testmod_ksym_percpu': not found in kernel BTF
>   libbpf: failed to load object 'test_ksyms_module'
>   libbpf: failed to load BPF skeleton 'test_ksyms_module': -22
>   test_ksyms_module_libbpf:FAIL:test_ksyms_module__open unexpected error: -22
>   #135/2   ksyms_module/libbpf:FAIL
>
>
>   [0] https://github.com/libbpf/libbpf/actions/runs/11204199648/job/31142297399#step:4:12480

Hi Andrii,

Thanks for the report.

The error: "'bpf_prog_active' not found in kernel BTF" sounds like it's
related to a bug that was present in v4 of this patch series:

https://lore.kernel.org/dwarves/ZwPob57HKYbfNpOH@x1/T/#t

Basically due to poor testing of a small refactor on my part, pahole
failed to emit almost all of the variables for BTF, so it would very
likely cause this error. And I think this broken commit may have been
hanging around in the git repository for the weekend, maybe Arnaldo can
confirm whether or not it was fixed up.

I cannot see the git SHA for the pahole branch which was used in this CI
run, so I can't say for sure. But I do see that the "tmp.master" branch
is now fixed up, so a re-run would verify whether this is the root
cause.

Thanks,
Stephen

Arnaldo Carvalho de Melo Oct. 7, 2024, 6:48 p.m. UTC | #5

On Mon, Oct 07, 2024 at 10:24:01AM -0700, Stephen Brennan wrote:
> Andrii Nakryiko <[e-mail]> writes:
> > On Fri, Oct 4, 2024 at 2:21 PM Arnaldo Carvalho de Melo <[e-mail]> wrote:
> >>
> >> On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
> >> > Hi all,
> >> >
> >> > This is v4 of the series which adds global variables to pahole's generated BTF.
> >> >
> >> > Since v3:
> >> >
> >> > 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
> >> > 2. Consistently start shndx loops at 1, and use size_t.
> >> > 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
> >> >
> >> > v3: https://lore.kernel.org/dwarves/[e-mail]/
> >> > v2: https://lore.kernel.org/dwarves/[e-mail]/
> >> > v1: https://lore.kernel.org/dwarves/[e-mail]/
> >> >
> >> > Thanks everyone for your review, tests, and consideration!
> >>
> >> Looks ok, I run the existing regression tests:
> >>
> >> acme@x1:~/git/pahole$ tests/tests
> >>   1: Validation of BTF encoding of functions; this may take some time: Ok
> >>   2: Pretty printing of files using DWARF type information: Ok
> >>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
> >> /home/acme/git/pahole
> >> acme@x1:~/git/pahole$
> >>
> >> And now I'm building a kernel with clang + Thin LTO + Rust enabled in
> >> the kernel to test other fixes I have merged and doing that with your
> >> patch series.
> >>
> >> Its all in the next branch and will move to master later today or
> >> tomorrow when I finish the clang+LTO+Rust tests.
> >
> > pahole-staging testing in libbpf CI started failing recently, can you
> > please double-check and see if this was caused by these changes? They
> > seem to be related to encoding BTF for per-CPU global variables, so
> > might be relevant ([0] for full run logs)
> >
> >   #33      btf_dump:FAIL
> >   libbpf: extern (var ksym) 'bpf_prog_active': not found in kernel BTF
> >   libbpf: failed to load object 'kfunc_call_test_subprog'
> >   libbpf: failed to load BPF skeleton 'kfunc_call_test_subprog': -22
> >   test_subprog:FAIL:skel unexpected error: -22
> >   #126/17  kfunc_call/subprog:FAIL
> >   test_subprog_lskel:FAIL:skel unexpected error: -2
> >   #126/18  kfunc_call/subprog_lskel:FAIL
> >   #126     kfunc_call:FAIL
> >   test_ksyms_module_lskel:FAIL:test_ksyms_module_lskel__open_and_load
> > unexpected error: -2
> >   #135/1   ksyms_module/lskel:FAIL
> >   libbpf: extern (var ksym) 'bpf_testmod_ksym_percpu': not found in kernel BTF
> >   libbpf: failed to load object 'test_ksyms_module'
> >   libbpf: failed to load BPF skeleton 'test_ksyms_module': -22
> >   test_ksyms_module_libbpf:FAIL:test_ksyms_module__open unexpected error: -22
> >   #135/2   ksyms_module/libbpf:FAIL
> >
> >
> >   [0] https://github.com/libbpf/libbpf/actions/runs/11204199648/job/31142297399#step:4:12480
> 
> Hi Andrii,
> 
> Thanks for the report.
> 
> The error: "'bpf_prog_active' not found in kernel BTF" sounds like it's
> related to a bug that was present in v4 of this patch series:
> 
> https://lore.kernel.org/dwarves/ZwPob57HKYbfNpOH@x1/T/#t
> 
> Basically due to poor testing of a small refactor on my part, pahole
> failed to emit almost all of the variables for BTF, so it would very
> likely cause this error. And I think this broken commit may have been
> hanging around in the git repository for the weekend, maybe Arnaldo can
> confirm whether or not it was fixed up.
> 
> I cannot see the git SHA for the pahole branch which was used in this CI
> run, so I can't say for sure. But I do see that the "tmp.master" branch
> is now fixed up, so a re-run would verify whether this is the root
> cause.

right, that is a piece of info I sometimes miss, the SHA used for the
test run, but today's test is in progress and should have the fix for
the inverted logic, we'll see...


- Arnaldo

Arnaldo Carvalho de Melo Oct. 7, 2024, 7 p.m. UTC | #6

On Mon, Oct 07, 2024 at 03:48:16PM -0300, Arnaldo Carvalho de Melo wrote:
> On Mon, Oct 07, 2024 at 10:24:01AM -0700, Stephen Brennan wrote:
> > Andrii Nakryiko <[e-mail]> writes:
> > > On Fri, Oct 4, 2024 at 2:21 PM Arnaldo Carvalho de Melo <[e-mail]> wrote:
> > >>
> > >> On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
> > >> > Hi all,
> > >> >
> > >> > This is v4 of the series which adds global variables to pahole's generated BTF.
> > >> >
> > >> > Since v3:
> > >> >
> > >> > 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
> > >> > 2. Consistently start shndx loops at 1, and use size_t.
> > >> > 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
> > >> >
> > >> > v3: https://lore.kernel.org/dwarves/[e-mail]/
> > >> > v2: https://lore.kernel.org/dwarves/[e-mail]/
> > >> > v1: https://lore.kernel.org/dwarves/[e-mail]/
> > >> >
> > >> > Thanks everyone for your review, tests, and consideration!
> > >>
> > >> Looks ok, I run the existing regression tests:
> > >>
> > >> acme@x1:~/git/pahole$ tests/tests
> > >>   1: Validation of BTF encoding of functions; this may take some time: Ok
> > >>   2: Pretty printing of files using DWARF type information: Ok
> > >>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
> > >> /home/acme/git/pahole
> > >> acme@x1:~/git/pahole$
> > >>
> > >> And now I'm building a kernel with clang + Thin LTO + Rust enabled in
> > >> the kernel to test other fixes I have merged and doing that with your
> > >> patch series.
> > >>
> > >> Its all in the next branch and will move to master later today or
> > >> tomorrow when I finish the clang+LTO+Rust tests.
> > >
> > > pahole-staging testing in libbpf CI started failing recently, can you
> > > please double-check and see if this was caused by these changes? They
> > > seem to be related to encoding BTF for per-CPU global variables, so
> > > might be relevant ([0] for full run logs)
> > >
> > >   #33      btf_dump:FAIL
> > >   libbpf: extern (var ksym) 'bpf_prog_active': not found in kernel BTF
> > >   libbpf: failed to load object 'kfunc_call_test_subprog'
> > >   libbpf: failed to load BPF skeleton 'kfunc_call_test_subprog': -22
> > >   test_subprog:FAIL:skel unexpected error: -22
> > >   #126/17  kfunc_call/subprog:FAIL
> > >   test_subprog_lskel:FAIL:skel unexpected error: -2
> > >   #126/18  kfunc_call/subprog_lskel:FAIL
> > >   #126     kfunc_call:FAIL
> > >   test_ksyms_module_lskel:FAIL:test_ksyms_module_lskel__open_and_load
> > > unexpected error: -2
> > >   #135/1   ksyms_module/lskel:FAIL
> > >   libbpf: extern (var ksym) 'bpf_testmod_ksym_percpu': not found in kernel BTF
> > >   libbpf: failed to load object 'test_ksyms_module'
> > >   libbpf: failed to load BPF skeleton 'test_ksyms_module': -22
> > >   test_ksyms_module_libbpf:FAIL:test_ksyms_module__open unexpected error: -22
> > >   #135/2   ksyms_module/libbpf:FAIL
> > >
> > >
> > >   [0] https://github.com/libbpf/libbpf/actions/runs/11204199648/job/31142297399#step:4:12480
> > 
> > Hi Andrii,
> > 
> > Thanks for the report.
> > 
> > The error: "'bpf_prog_active' not found in kernel BTF" sounds like it's
> > related to a bug that was present in v4 of this patch series:
> > 
> > https://lore.kernel.org/dwarves/ZwPob57HKYbfNpOH@x1/T/#t
> > 
> > Basically due to poor testing of a small refactor on my part, pahole
> > failed to emit almost all of the variables for BTF, so it would very
> > likely cause this error. And I think this broken commit may have been
> > hanging around in the git repository for the weekend, maybe Arnaldo can
> > confirm whether or not it was fixed up.
> > 
> > I cannot see the git SHA for the pahole branch which was used in this CI
> > run, so I can't say for sure. But I do see that the "tmp.master" branch
> > is now fixed up, so a re-run would verify whether this is the root
> > cause.
> 
> right, that is a piece of info I sometimes miss, the SHA used for the
> test run, but today's test is in progress and should have the fix for
> the inverted logic, we'll see...

https://github.com/libbpf/libbpf/actions/runs/11221662157/job/31192457160

Passed, so and here as well:

acme@x1:~/git/pahole$ tests/tests 
  1: Validation of BTF encoding of functions; this may take some time: Ok
  2: Pretty printing of files using DWARF type information: Ok
  3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
acme@x1:~/git/pahole$

- Arnaldo

Andrii Nakryiko Oct. 7, 2024, 9:46 p.m. UTC | #7

On Mon, Oct 7, 2024 at 12:00 PM Arnaldo Carvalho de Melo
<[e-mail]> wrote:
>
> On Mon, Oct 07, 2024 at 03:48:16PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Mon, Oct 07, 2024 at 10:24:01AM -0700, Stephen Brennan wrote:
> > > Andrii Nakryiko <[e-mail]> writes:
> > > > On Fri, Oct 4, 2024 at 2:21 PM Arnaldo Carvalho de Melo <[e-mail]> wrote:
> > > >>
> > > >> On Fri, Oct 04, 2024 at 10:26:24AM -0700, Stephen Brennan wrote:
> > > >> > Hi all,
> > > >> >
> > > >> > This is v4 of the series which adds global variables to pahole's generated BTF.
> > > >> >
> > > >> > Since v3:
> > > >> >
> > > >> > 1. Gathered Alan's Reviewed-by + Tested-by, and Jiri's Acked-by.
> > > >> > 2. Consistently start shndx loops at 1, and use size_t.
> > > >> > 3. Since patch 1 of v3 was already applied, I dropped it out of this series.
> > > >> >
> > > >> > v3: https://lore.kernel.org/dwarves/[e-mail]/
> > > >> > v2: https://lore.kernel.org/dwarves/[e-mail]/
> > > >> > v1: https://lore.kernel.org/dwarves/[e-mail]/
> > > >> >
> > > >> > Thanks everyone for your review, tests, and consideration!
> > > >>
> > > >> Looks ok, I run the existing regression tests:
> > > >>
> > > >> acme@x1:~/git/pahole$ tests/tests
> > > >>   1: Validation of BTF encoding of functions; this may take some time: Ok
> > > >>   2: Pretty printing of files using DWARF type information: Ok
> > > >>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
> > > >> /home/acme/git/pahole
> > > >> acme@x1:~/git/pahole$
> > > >>
> > > >> And now I'm building a kernel with clang + Thin LTO + Rust enabled in
> > > >> the kernel to test other fixes I have merged and doing that with your
> > > >> patch series.
> > > >>
> > > >> Its all in the next branch and will move to master later today or
> > > >> tomorrow when I finish the clang+LTO+Rust tests.
> > > >
> > > > pahole-staging testing in libbpf CI started failing recently, can you
> > > > please double-check and see if this was caused by these changes? They
> > > > seem to be related to encoding BTF for per-CPU global variables, so
> > > > might be relevant ([0] for full run logs)
> > > >
> > > >   #33      btf_dump:FAIL
> > > >   libbpf: extern (var ksym) 'bpf_prog_active': not found in kernel BTF
> > > >   libbpf: failed to load object 'kfunc_call_test_subprog'
> > > >   libbpf: failed to load BPF skeleton 'kfunc_call_test_subprog': -22
> > > >   test_subprog:FAIL:skel unexpected error: -22
> > > >   #126/17  kfunc_call/subprog:FAIL
> > > >   test_subprog_lskel:FAIL:skel unexpected error: -2
> > > >   #126/18  kfunc_call/subprog_lskel:FAIL
> > > >   #126     kfunc_call:FAIL
> > > >   test_ksyms_module_lskel:FAIL:test_ksyms_module_lskel__open_and_load
> > > > unexpected error: -2
> > > >   #135/1   ksyms_module/lskel:FAIL
> > > >   libbpf: extern (var ksym) 'bpf_testmod_ksym_percpu': not found in kernel BTF
> > > >   libbpf: failed to load object 'test_ksyms_module'
> > > >   libbpf: failed to load BPF skeleton 'test_ksyms_module': -22
> > > >   test_ksyms_module_libbpf:FAIL:test_ksyms_module__open unexpected error: -22
> > > >   #135/2   ksyms_module/libbpf:FAIL
> > > >
> > > >
> > > >   [0] https://github.com/libbpf/libbpf/actions/runs/11204199648/job/31142297399#step:4:12480
> > >
> > > Hi Andrii,
> > >
> > > Thanks for the report.
> > >
> > > The error: "'bpf_prog_active' not found in kernel BTF" sounds like it's
> > > related to a bug that was present in v4 of this patch series:
> > >
> > > https://lore.kernel.org/dwarves/ZwPob57HKYbfNpOH@x1/T/#t
> > >
> > > Basically due to poor testing of a small refactor on my part, pahole
> > > failed to emit almost all of the variables for BTF, so it would very
> > > likely cause this error. And I think this broken commit may have been
> > > hanging around in the git repository for the weekend, maybe Arnaldo can
> > > confirm whether or not it was fixed up.
> > >
> > > I cannot see the git SHA for the pahole branch which was used in this CI
> > > run, so I can't say for sure. But I do see that the "tmp.master" branch
> > > is now fixed up, so a re-run would verify whether this is the root
> > > cause.
> >
> > right, that is a piece of info I sometimes miss, the SHA used for the
> > test run, but today's test is in progress and should have the fix for
> > the inverted logic, we'll see...
>
> https://github.com/libbpf/libbpf/actions/runs/11221662157/job/31192457160
>
> Passed, so and here as well:

Ok, great! Seems like I was either too slow or too fast with reporting
this, depending how you look at this :)

>
> acme@x1:~/git/pahole$ tests/tests
>   1: Validation of BTF encoding of functions; this may take some time: Ok
>   2: Pretty printing of files using DWARF type information: Ok
>   3: Parallel reproducible DWARF Loading/Serial BTF encoding: Ok
> acme@x1:~/git/pahole$
>
> - Arnaldo