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

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Date:   Tue, 21 Dec 2021 08:58:34 +0800
From:   Pu Lehui <pulehui@...wei.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, Martin Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        john fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Shuah Khan <shuah@...nel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next] selftests/bpf: Fix building error when using
 userspace pt_regs



On 2021/12/20 22:02, Pu Lehui wrote:
> 
> 
> On 2021/12/18 0:45, Andrii Nakryiko wrote:
>> On Thu, Dec 16, 2021 at 6:25 PM Pu Lehui <pulehui@...wei.com> wrote:
>>>
>>>
>>>
>>> On 2021/12/16 12:06, Andrii Nakryiko wrote:
>>>> On Tue, Dec 14, 2021 at 5:54 AM Pu Lehui <pulehui@...wei.com> 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.
>>>>
>>>> We could probably also extend bpf_tracing.h to work with
>>>> kernel-defined pt_regs, just like we do for x86 (see __KERNEL__ and
>>>> __VMLINUX_H__ checks). It's more work, but will benefit other end
>>>> users, not just selftests.
>>>>
>>> It might change a lot. We can use header file directory generated by
>>> "make headers_install" to fix it.
>>
>> We don't have dependency on "make headers_install" and I'd rather not 
>> add it.
>>
>> What do you mean by "change a lot"?
>>
> Maybe I misunderstood your advice. Your suggestion might be to extend 
> bpf_tracing.h to kernel-space pt_regs, while some archs, like arm64, 
> only support user-space. So the patch might be like this:
> 
> diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
> index db05a5937105..2c3cb8e9ae92 100644
> --- a/tools/lib/bpf/bpf_tracing.h
> +++ b/tools/lib/bpf/bpf_tracing.h
> @@ -195,9 +195,13 @@ struct pt_regs;
> 
>   #elif defined(bpf_target_arm64)
> 
> -struct pt_regs;
> +#if defined(__KERNEL__)
> +#define PT_REGS_ARM64 const volatile struct pt_regs
> +#else
>   /* arm64 provides struct user_pt_regs instead of struct pt_regs to 
> userspace */
>   #define PT_REGS_ARM64 const volatile struct user_pt_regs
> +#endif
> +
>   #define PT_REGS_PARM1(x) (((PT_REGS_ARM64 *)(x))->regs[0])
>   #define PT_REGS_PARM2(x) (((PT_REGS_ARM64 *)(x))->regs[1])
>   #define PT_REGS_PARM3(x) (((PT_REGS_ARM64 *)(x))->regs[2])
> 
Please ignore the last reply. User-space pt_regs of arm64/s390 is the 
first part of the kernel-space's, it should has covered both kernel and 
userspace.
>>>
>>> --- 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
>>>>>
>>>>> Signed-off-by: Pu Lehui <pulehui@...wei.com>
>>>>> ---
>>>>>    tools/testing/selftests/bpf/progs/loop1.c     |  8 ++------
>>>>>    tools/testing/selftests/bpf/progs/loop2.c     |  8 ++------
>>>>>    tools/testing/selftests/bpf/progs/loop3.c     |  8 ++------
>>>>>    tools/testing/selftests/bpf/progs/loop6.c     | 20 
>>>>> ++++++-------------
>>>>>    .../selftests/bpf/progs/test_overhead.c       |  8 ++------
>>>>>    .../selftests/bpf/progs/test_probe_user.c     |  6 +-----
>>>>>    6 files changed, 15 insertions(+), 43 deletions(-)
>>>>>
>>>>
>>>> [...]
>>>> .
>>>>
>> .
>>
> .