Messages in this thread | | | Subject | Re: [PATCH 05/31] perf record: Load eBPF object into kernel | From | pi3orama <> | Date | Sat, 24 Oct 2015 09:18:56 +0800 |
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发自我的 iPhone
> 在 2015年10月24日,上午12:58,Arnaldo Carvalho de Melo <acme@kernel.org> 写道: > > Em Wed, Oct 14, 2015 at 12:41:16PM +0000, Wang Nan escreveu: >> This patch utilizes bpf_object__load() provided by libbpf to load all >> objects into kernel. > > So, testing this, using that other proggie, I get; > > # perf record --event /tmp/foo.o sleep 1 > libbpf: load bpf program failed: Invalid argument > libbpf: -- BEGIN DUMP LOG --- > libbpf: > > libbpf: -- END LOG --
This means your kernel version and version section in your BPF object doesn't match each other. Please try to pass a correct version code when compiling the object. I think we should output something through error log so by -v we can see the problem. I told Alexei about this problem once. Let me improve perf's error message next week.
Thank you.
> libbpf: failed to load program 'fork=_do_fork' > libbpf: failed to load object '/tmp/foo.o' > event syntax error: '/tmp/foo.o' > \___ Invalid argument: Are you root and runing a CONFIG_BPF_SYSCALL kernel? > > (add -v to see detail) > Run 'perf list' for a list of valid events > > Usage: perf record [<options>] [<command>] > or: perf record [<options>] -- <command> [<options>] > > -e, --event <event> event selector. use 'perf list' to list available events > > But: > > [root@felicio ~]# grep -i bpf /proc/kallsyms | wc -l > 117 > [root@felicio ~]# grep -i sys_bpf /proc/kallsyms > ffffffff811829d0 T SyS_bpf > ffffffff811829d0 T sys_bpf > [root@felicio ~]# uname -a > Linux felicio.ghostprotocols.net 4.2.0 #1 SMP Mon Aug 31 12:25:38 BRT > 2015 x86_64 x86_64 x86_64 GNU/Linux > [root@felicio ~]# > > > I'll try updating it to torvalds/master... > > For reference, that foo.o eBPF proggie was built with: > > [acme@felicio linux]$ cat ~/bin/hello-ebpf > # Taken from 'perf test LLVM' > # Thu Oct 22 12:07:26 BRT 2015 > > export KERNEL_INC_OPTIONS="-nostdinc -isystem > /usr/lib/gcc/x86_64-redhat-linux/4.8.3/include > -I/home/acme/git/linux/arch/x86/include > -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated > -I/home/acme/git/linux/include -Iinclude > -I/home/acme/git/linux/arch/x86/include/uapi > -Iarch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi > -Iinclude/generated/uapi -include > /home/acme/git/linux/include/linux/kconfig.h" > export WORKING_DIR=/lib/modules/4.2.0/build > export CLANG_SOURCE=- > export CLANG_OPTIONS=-xc > > OBJ=/tmp/foo.o > rm -f $OBJ > echo '__attribute__((section("fork=_do_fork"), used)) int fork(void > *ctx) {return 0;} char _license[] __attribute__((section("license"), > used)) = "GPL";int _version __attribute__((section("version"), used)) = > 0x40100;' | clang -D__KERNEL__ $CLANG_OPTIONS $KERNEL_INC_OPTIONS > -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c > "$CLANG_SOURCE" -target bpf -O2 -o /tmp/foo.o && file $OBJ > > - Arnaldo
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