Subject: Re: [PATCH bpf-next v2] selftests/bpf: Fix cross compiling error when
 using userspace pt_regs
To:     Andrii Nakryiko <andrii.nakryiko@gmail.com>
CC:     "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20211223052007.4111674-1-pulehui@huawei.com>
 <CAEf4BzY29kWicH0fdh9NnYu4nn1E4odL2ES2EYTGkyvHbo2c4g@mail.gmail.com>
From:   Pu Lehui <pulehui@huawei.com>
Message-ID: <6bf1e9cb-77c8-7bb8-c55d-bf85a09819cd@huawei.com>
Date:   Fri, 24 Dec 2021 10:57:52 +0800
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On 2021/12/24 2:21, Andrii Nakryiko wrote:
> On Wed, Dec 22, 2021 at 8:56 PM Pu Lehui <pulehui@huawei.com> 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@huawei.com>
>> ---
>> 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@kernel.org/
> 
> 
OK, I'll keep follow it.
>>   CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
>>                 -Wno-compare-distinct-pointer-types
>> --
>> 2.25.1
>>
> .
>