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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Wed, 13 Nov 2019 15:57:22 +0900
Message-ID: <CAK7LNARKh3-cAqsYgcxFwq9CGk-CgBfkiQgfNSULkxwO0xa2vw@mail.gmail.com>
Subject: Re: Question about "asm/rwonce.h: No such file or directory"
To:     Xiao Yang <ice_yangxiao@163.com>
Cc:     Daniel Borkmann <daniel@iogearbox.net>,
        Will Deacon <will@kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alexei Starovoitov <ast@kernel.org>
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On Wed, Nov 13, 2019 at 2:52 PM Xiao Yang <ice_yangxiao@163.com> wrote:
>
> On 11/13/19 1:28 PM, Masahiro Yamada wrote:
> > On Wed, Nov 13, 2019 at 12:13 AM Daniel Borkmann <daniel@iogearbox.net> wrote:
> >> On 11/12/19 1:50 PM, Masahiro Yamada wrote:
> >>> On Tue, Nov 12, 2019 at 9:31 PM Will Deacon <will@kernel.org> wrote:
> >>>> [+lkml, Masahiro, Alexei and Daniel]
> >>>>
> >>>> On Tue, Nov 12, 2019 at 04:56:39PM +0800, Xiao Yang wrote:
> >>>>> With your patch[1], I alway get the following error when building
> >>>>> tools/bpf:
> >>>> In case people want to reproduce this, my branch is here:
> >>>>
> >>>> https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=lto
> >>>>
> >>>>> ----------------------------------------------------------------------------------
> >>>>>
> >>>>> make -C tools/bpf/
> >>>>> make: Entering directory
> >>>>> '/usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/tools/bpf'
> >>>>>
> >>>>> Auto-detecting system features:
> >>>>> ... libbfd: [ on ]
> >>>>> ... disassembler-four-args: [ OFF ]
> >>>>>
> >>>>> CC bpf_jit_disasm.o
> >>>>> CC bpf_dbg.o
> >>>>> In file included from
> >>>>> /usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/include/uapi/linux/filter.h:9:0,
> >>>>> from
> >>>>> /usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/tools/bpf/bpf_dbg.c:41:
> >>>>> /usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/include/linux/compiler.h:247:24:
> >>>>> fatal error: asm/rwonce.h: No such file or directory
> >>>>> #include <asm/rwonce.h>
> >>>>> ^
> >>>>> compilation terminated.
> >>>>> Makefile:61: recipe for target 'bpf_dbg.o' failed
> >>>>> make: *** [bpf_dbg.o] Error 1
> >>>>> make: *** Waiting for unfinished jobs....
> >>>>> make: Leaving directory
> >>>>>
> >>>>> ----------------------------------------------------------------------------------
> >>>>>
> >>>>> [1] https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/commit/?h=lto&id=642a312d47ceb54603630d9d04f5052f3b46d9a3
> >>>>>
> >>>>> It seems that include/linux/compiler.h cannot find the asm/rwonce.h because
> >>>>> tools/bpf/Makefile doesn't include arch/*/include/generated/asm/rwonce.h.
> >>>> The problem with referring to the generated files is that they don't exist
> >>>> unless you've configured the main source directory. The real problem here
> >>>> seems to be that tools/bpf/ refers directly to header files in the kernel
> >>>> sources without any understanding of kbuild, and therefore mandatory-y
> >>>> headers simply don't exist when it goes looking for them.
> >> Hmm, I am puzzled why that is. :/ I think there are two options, i) remove it
> >> from CFLAGS like below (at least this doesn't let the build fail in my case
> >> but requires linux headers to be installed) or ii) add a copy of filter.h to
> >> tools/include/uapi/linux/filter.h so the few tools can just reuse it. We do have
> >> bpf_common.h and bpf.h there already.
> >>
> >> diff --git a/tools/bpf/Makefile b/tools/bpf/Makefile
> >> index 5d1995fd369c..08dfd289174c 100644
> >> --- a/tools/bpf/Makefile
> >> +++ b/tools/bpf/Makefile
> >> @@ -10,7 +10,6 @@ MAKE = make
> >>    INSTALL ?= install
> >>
> >>    CFLAGS += -Wall -O2
> >> -CFLAGS += -D__EXPORTED_HEADERS__ -I$(srctree)/include/uapi -I$(srctree)/include
> >>
> >>    # This will work when bpf is built in tools env. where srctree
> >>    # isn't set and when invoked from selftests build, where srctree
> >>
> >
> > I think this is the most sane fix
> > to include the linux/filter.h in the system.
> >
> > (probably, it is located in /usr/include/linux/filter.h)
>
> Hi Masahiro,
>
> Is it correct for include/linux/compiler.h to include <asm/rwonce.h>?


Sorry, I really do not understand what you are doing.

include/linux/compiler.h is only for kernel-space.
Shrug if a user-land program includes it.


> On x86_64 arch, asm/rwonce.h is generated in
> ./arch/x86/include/generated/ directory and compiler.h cannot find it.
>
> Best Regards,
>
> XIao Yang
>
> >
> >
>


-- 
Best Regards
Masahiro Yamada