On Mon, Feb 01, 2021 at 09:25:32AM -0300, Arnaldo Carvalho de Melo wrote: > Em Sun, Jan 31, 2021 at 10:36:41PM +0100, Jiri Olsa escreveu: > > On Sat, Jan 30, 2021 at 09:48:13PM +0100, Jiri Olsa wrote: > > > > SNIP > > > > > > > > > % uname -r > > > > > > > 5.11.0-0.rc5.134.fc34.x86_64 > > > > > > > % pwd > > > > > > > /.../linux/tools/testing/selftests/bpf > > > > > > > % git log --oneline | head -n 1 > > > > > > > 6ee1d745b7c9 Linux 5.11-rc5 > > > > > > > % make test_verifier_log > > > > > > > ... > > > > > > > BINARY test_verifier_log > > > > > > > % ./test_verifier_log > > > > > > > Test log_level 0... > > > > > > > Test log_size < 128... > > > > > > > Test log_buff = NULL... > > > > > > > Test oversized buffer... > > > > > > > ERROR: Program load returned: ret:-1/errno:22, expected ret:-1/errno:13 > > > > > > > > > > > > Thanks for reporting. > > > > > > bpf and bpf-next don't have this issue. Not sure what changed. > > > > > > > > > > I haven't had a chance to look into this any further, but Ondrej > > > > > Mosnacek (CC'd) found the following today: > > > > > > > > > > "So I was trying to debug this further and I think I've identified what > > > > > triggers the problem. It seems that the BTF debuginfo generation > > > > > became broken with CONFIG_DEBUG_INFO_DWARF4=n somewhere between -rc4 > > > > > and -rc5. It also seems to depend on a recent (Fedora Rawhide) version > > > > > of some component of the build system (GCC, probably), because the > > > > > problem disappeared when I tried to build the "bad" kernel in F33 > > > > > buildroot instead of Rawhide." > > > > > > > > I see. There were fixes for dwarf and btf, but I lost the track. > > > > I believe it was a combination of gcc bug that was worked around in pahole. > > > > Arnaldo, Jiri, Andrii, > > > > what is the status? Did all fixes land in pahole? > > > > > > I checked on rawhide and besides many pahole warnings, > > > the resulted BTF data have many duplications in core structs > > > > > > BTFIDS vmlinux > > > WARN: multiple IDs found for 'task_struct': 132, 1247 - using 132 > > > WARN: multiple IDs found for 'file': 440, 1349 - using 440 > > > WARN: multiple IDs found for 'inode': 698, 1645 - using 698 > > > WARN: multiple IDs found for 'path': 729, 1672 - using 729 > > > WARN: multiple IDs found for 'task_struct': 132, 2984 - using 132 > > > WARN: multiple IDs found for 'task_struct': 132, 3043 - using 132 > > > WARN: multiple IDs found for 'file': 440, 3085 - using 440 > > > WARN: multiple IDs found for 'seq_file': 1469, 3125 - using 1469 > > > WARN: multiple IDs found for 'inode': 698, 3336 - using 698 > > > WARN: multiple IDs found for 'path': 729, 3366 - using 729 > > > WARN: multiple IDs found for 'task_struct': 132, 5337 - using 132 > > > WARN: multiple IDs found for 'inode': 698, 5360 - using 698 > > > WARN: multiple IDs found for 'path': 729, 5388 - using 729 > > > WARN: multiple IDs found for 'file': 440, 5412 - using 440 > > > WARN: multiple IDs found for 'seq_file': 1469, 5639 - using 1469 > > > WARN: multiple IDs found for 'task_struct': 132, 6243 - using 132 > > > ... > > > > > > # gcc --version > > > gcc (GCC) 11.0.0 20210123 (Red Hat 11.0.0-0) > > > > > > I'm guessing there are some DWARF changes that screwed BTF > > > generation.. I'll check > > > > > > it's not covered by the fix I posted recently, but I think > > > Arnaldo is now fixing some related stuff.. Arnaldo, maybe > > > you are seeing same errors? > > > > with Arnaldo's fixes I see less struct duplications, > > but still there's some > > > > > > > > I uploaded the build log from linking part to: > > > http://people.redhat.com/~jolsa/build.out.gz > > > > however looks like we don't handle DW_FORM_implicit_const > > when counting the byte offset.. it was used for some struct > > members in my vmlinux, so we got zero for byte offset and > > that created another unique struct > > > > with patch below I no longer see any struct duplication, > > also test_verifier_log is working for me, but I could > > not reproduce the error before > > > > I'll post full dwarves patch after some more testing > > > > also I wonder we could somehow use btf_check_all_metas > > from kernel after we build BTF data, that'd help to catch > > this earlier/easier ;-) I'll check on this > > Seems like a good idea indeed :-) > > I'm applying the patch below with your Signed-off-by, etc, ok? ok, thanks jirka
