Re: [PATCH bpf-next] selftests/bpf: Fix building error when using userspace pt_regs

[Pu Lehui]

On 2021/12/15 9:20, Pu Lehui wrote:
> On 2021/12/15 4:01, Daniel Borkmann wrote:
> > On 12/14/21 2:55 PM, Pu Lehui wrote:
> > > When building bpf selftests on arm64, the following error will occur:
> > >
> > > progs/loop2.c:20:7: error: incomplete definition of type 'struct
> > > user_pt_regs'
> > >
> > > Some archs, like arm64 and riscv, use userspace pt_regs in
> > > bpf_tracing.h, which causes build failure when bpf prog use
> > > macro in bpf_tracing.h. So let's use vmlinux.h directly.
> > >
> > > Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
> >
> > Looks like this lets CI fail, did you run the selftests also with 
> > vmtest.sh to
> > double check?
> >
> > https://github.com/kernel-patches/bpf/runs/4521708490?check_suite_focus=true 
> > :
> >
> > [...]
> > #189 verif_scale_loop6:FAIL
> > libbpf: prog 'trace_virtqueue_add_sgs': BPF program load failed: 
> > Argument list too long
> > libbpf: prog 'trace_virtqueue_add_sgs': -- BEGIN PROG LOAD LOG --
> > R1 type=ctx expected=fp
> > BPF program is too large. Processed 1000001 insn
> > verification time 12250995 usec
> > stack depth 88
> > processed 1000001 insns (limit 1000000) max_states_per_insn 107 
> > total_states 21739 peak_states 2271 mark_read 6
> > -- END PROG LOAD LOG --
> > libbpf: failed to load program 'trace_virtqueue_add_sgs'
> > libbpf: failed to load object 'loop6.o'
> > scale_test:FAIL:expect_success unexpected error: -7 (errno 7)
> > Summary: 221/986 PASSED, 8 SKIPPED, 1 FAILED
> > [...]
> >
> > Please take a look and fix in your patch, thanks!
> > .
> Sorry for my negligence, I'll take a look and fix it.
> .
It seems strange that verifier think the loop can execute up to u64_max 
while I just replace the header file.
This looks very similar to the previous llvm issue, 
https://github.com/iovisor/bcc/pull/3270, but I have no idea how to locate.

Back to arm64 bpf selftest compiling problem, we can use header file 
directory generated by "make headers_install" to fix it.

--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -294,7 +294,8 @@ MENDIAN=$(if 
$(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
 CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
 BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \
 	     -I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR) \
-	     -I$(abspath $(OUTPUT)/../usr/include)
+	     -I$(abspath $(OUTPUT)/../usr/include) \
+	     -I../../../../usr/include