netdev - Re: [PATCH bpf-next v5 00/10] BTF: BPF Type Format

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Message-ID: <20180613232638.yyhktiovl6oeawgt@kafai-mbp>
Date:   Wed, 13 Jun 2018 16:26:38 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
CC:     <netdev@...r.kernel.org>, Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH bpf-next v5 00/10] BTF: BPF Type Format

On Tue, Jun 12, 2018 at 05:41:26PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, Jun 12, 2018 at 05:31:24PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Thu, Jun 07, 2018 at 01:07:01PM -0700, Martin KaFai Lau escreveu:
> > > On Thu, Jun 07, 2018 at 04:30:29PM -0300, Arnaldo Carvalho de Melo wrote:
> > > > So this must be available in a newer llvm version? Which one?
> > 
> > > I should have put in the details in my last email or
> > > in the commit message, my bad.
> >  
> > > 1. The tools/testing/selftests/bpf/Makefile has the CLANG_FLAGS and
> > >    LLC_FLAGS needed to compile the bpf prog.  It requires a new
> > >    "-mattr=dwarf" llc option which was added to the future
> > >    llvm 7.0.
> 
> > [root@...et bpf]# pahole hello.o
> > struct clang version 5.0.1 (tags/RELEASE_501/final) {
> > 	clang version 5.0.1 (tags/RELEASE_501/final) clang version 5.0.1 (tags/RELEASE_501/final); /*     0     4 */
> > 	clang version 5.0.1 (tags/RELEASE_501/final) clang version 5.0.1 (tags/RELEASE_501/final); /*     4     4 */
> > 	clang version 5.0.1 (tags/RELEASE_501/final) clang version 5.0.1 (tags/RELEASE_501/final); /*     8     4 */
> > 	clang version 5.0.1 (tags/RELEASE_501/final) clang version 5.0.1 (tags/RELEASE_501/final); /*    12     4 */
> > 
> > 	/* size: 16, cachelines: 1, members: 4 */
> > 	/* last cacheline: 16 bytes */
> > };
> > [root@...et bpf]# 
> > 
> > Ok, I guess I saw this case in the llvm/clang git logs, so this one was
> > generated with the older clang, will regenerate and add that "-mattr=dwarf"
> > part.
> 
> [root@...et bpf]# pahole hello.o
> struct clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78e82f54be8fb0bb5f02e3ca674fbde10ef34) {
> 	clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78 clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78e82f54be8fb0bb5f02e3ca674fbde10ef34); /*     0     4 */
> 	clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78 clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78e82f54be8fb0bb5f02e3ca674fbde10ef34); /*     4     4 */
> 	clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78 clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78e82f54be8fb0bb5f02e3ca674fbde10ef34); /*     8     4 */
> 	clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78 clang version 7.0.0 (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_clang.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=_Qzsu689xEjjl9JvYCvJsIZLZZKDLB6rM-Uc0gqQvyg&e= 8c873daccce7ee5339b9fd82c81fe02b73543b65) (https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_git_llvm.git&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=i6WobKxbeG3slzHSIOxTVtYIJw7qjCE6S0spDTKL-J4&m=4d495SlcvobgBOFahId75gM-V2su4Qq2wiLOGkU-adI&s=cFz6VP_YIYy_hubsx05WDqpTDyXl0Wnx_RAmAl1dbpg&e= 98c78e82f54be8fb0bb5f02e3ca674fbde10ef34); /*    12     4 */
> 
> 	/* size: 16, cachelines: 1, members: 4 */
> 	/* last cacheline: 16 bytes */
> };
That means the "-mattr=dwarf" is not effective.
Can you share your clang and llc command to create hello.o?

> [root@...et bpf]#
> 
> Ideas?
> 
> [root@...et bpf]# trace -e open*,hello.c
> clang-6.0: error: unknown argument: '-mattr=dwarf'
> ERROR:	unable to compile hello.c
> Hint:	Check error message shown above.
> Hint:	You can also pre-compile it into .o using:
>      		clang -target bpf -O2 -c hello.c
>      	with proper -I and -D options.
> event syntax error: 'hello.c'
>                      \___ Failed to load hello.c from source: Error when compiling BPF scriptlet
> 
> (add -v to see detail)
> Run 'perf list' for a list of valid events
> 
>  Usage: perf trace [<options>] [<command>]
>     or: perf trace [<options>] -- <command> [<options>]
>     or: perf trace record [<options>] [<command>]
>     or: perf trace record [<options>] -- <command> [<options>]
> 
>     -e, --event <event>   event/syscall selector. use 'perf list' to list available events
> [root@...et bpf]#
> 
> [root@...et bpf]# trace -v -e open*,hello.c
> bpf: builtin compilation failed: -95, try external compiler
> Kernel build dir is set to /lib/modules/4.17.0-rc5/build
> set env: KBUILD_DIR=/lib/modules/4.17.0-rc5/build
> unset env: KBUILD_OPTS
> include option is set to  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated  -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h 
> set env: NR_CPUS=4
> set env: LINUX_VERSION_CODE=0x41100
> set env: CLANG_EXEC=/usr/local/bin/clang
> set env: CLANG_OPTIONS=-g -mattr=dwarf
> set env: KERNEL_INC_OPTIONS= -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated  -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h 
> set env: PERF_BPF_INC_OPTIONS=-I/home/acme/lib/include/perf/bpf
> set env: WORKING_DIR=/lib/modules/4.17.0-rc5/build
> set env: CLANG_SOURCE=/home/acme/bpf/hello.c
> llvm compiling command template: $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS $PERF_BPF_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o -
> llvm compiling command : /usr/local/bin/clang -D__KERNEL__ -D__NR_CPUS__=4 -DLINUX_VERSION_CODE=0x41100 -g -mattr=dwarf  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated  -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h  -I/home/acme/lib/include/perf/bpf -Wno-unused-value -Wno-pointer-sign -working-directory /lib/modules/4.17.0-rc5/build -c /home/acme/bpf/hello.c -target bpf -O2 -o -
> clang-6.0: error: unknown argument: '-mattr=dwarf'
> ERROR:	unable to compile hello.c
> Hint:	Check error message shown above.
> Hint:	You can also pre-compile it into .o using:
>      		clang -target bpf -O2 -c hello.c
>      	with proper -I and -D options.
> event syntax error: 'hello.c'
>                      \___ Failed to load hello.c from source: Error when compiling BPF scriptlet
>