Re: [PATCH bpf-next v2] selftests/bpf: Fix cross compiling error when using userspace pt_regs

[Pu Lehui]

On 2021/12/24 2:21, Andrii Nakryiko wrote:
> On Wed, Dec 22, 2021 at 8:56 PM Pu Lehui <pulehui@xxxxxxxxxx> wrote:
> > When cross compiling arm64 bpf selftests in x86_64 host, the following
> > error 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.
> > When arm64 bpf selftests cross compiling in x86_64 host, clang cannot
> > find the arch specific uapi ptrace.h. We can add arch specific header
> > file directory to fix this issue.
> >
> > Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
> > ---
> > v1->v2:
> > - use vmlinux.h directly might lead to verifier fail.
> > - use source arch header file directory suggested by Andrii Nakryiko.
> >
> >   tools/testing/selftests/bpf/Makefile | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> > index 42ffc24e9e71..1ecb6d192953 100644
> > --- a/tools/testing/selftests/bpf/Makefile
> > +++ b/tools/testing/selftests/bpf/Makefile
> > @@ -12,6 +12,7 @@ BPFDIR := $(LIBDIR)/bpf
> >   TOOLSINCDIR := $(TOOLSDIR)/include
> >   BPFTOOLDIR := $(TOOLSDIR)/bpf/bpftool
> >   APIDIR := $(TOOLSINCDIR)/uapi
> > +ARCH_APIDIR := $(abspath ../../../../arch/$(SRCARCH)/include/uapi)
> >   GENDIR := $(abspath ../../../../include/generated)
> >   GENHDR := $(GENDIR)/autoconf.h
> >
> > @@ -294,7 +295,8 @@ MENDIAN=$(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 $(OUTPUT)/../usr/include)                      \
> > +            -I$(ARCH_APIDIR)
>
> This causes compilation error, see [0]. I think we'll have to wait for
> my patch ([1]) to land and then add kernel-side variants for accessing
> pt_regs.
>
>    [0] https://github.com/kernel-patches/bpf/runs/4614606900?check_suite_focus=true
>    [1] https://patchwork.kernel.org/project/netdevbpf/patch/20211222213924.1869758-1-andrii@xxxxxxxxxx/
OK, I'll keep follow it.
> >   CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
> >                 -Wno-compare-distinct-pointer-types
> > --
> > 2.25.1
> .