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SubjectRe: perf test BPF failing on 4.15.0-rc6
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Unable to reproduce. In my kernel configuration, SyS_epoll_wait is not 
inlined at all.

From the log you sent, it seems that all 3 instances are attached. This
testcase should work if the last one (SyS_epoll_wait) get probed correctly.

Could you please have a look if the 3rd kprobe event
(p:perf_bpf_probe/func_2 _text+2845824) works?

Thank you.

On 2018/1/3 2:59, Arnaldo Carvalho de Melo wrote:
> Hi Wang,
>
> I just updated my machine to Fedora 27 and 4.15.0-rc6 and the
> only test failing for me is:
>
> [root@jouet linux]# perf test bpf
> 39: BPF filter :
> 39.1: Basic BPF filtering : FAILED!
> 39.2: BPF pinning : Skip
> 39.3: BPF prologue generation : Skip
> 39.4: BPF relocation checker : Skip
> [root@jouet linux]#
>
> I haven't checked but perhaps the problem is that SyS_epoll_wait seems
> to now be inlined in three places and perhaps the eBPF proggie is being
> added to just one of them?
>
> Seemingly relevant excerpt:
>
> Open Debuginfo file: /lib/modules/4.15.0-rc6/build/vmlinux
> Try to find probe point from debuginfo.
> Matched function: SyS_epoll_wait [2f40eb7]
> found inline addr: 0xffffffff812b6ff1
> Probe point found: compat_SyS_epoll_pwait+129
> found inline addr: 0xffffffff812b6de7
> Probe point found: SyS_epoll_pwait+135
> found inline addr: 0xffffffff812b6c80
> Probe point found: SyS_epoll_wait+0
> Found 3 probe_trace_events.
>
> - Arnaldo
>
> P.S.: Full -v output:
>
> [root@jouet linux]# uname -a
> Linux jouet 4.15.0-rc6 #4 SMP Tue Jan 2 14:30:53 -03 2018 x86_64 x86_64 x86_64 GNU/Linux
> [root@jouet linux]# gcc -v
> Using built-in specs.
> COLLECT_GCC=/usr/bin/gcc
> COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/7/lto-wrapper
> OFFLOAD_TARGET_NAMES=nvptx-none
> OFFLOAD_TARGET_DEFAULT=1
> Target: x86_64-redhat-linux
> Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --enable-libmpx --enable-offload-targets=nvptx-none --without-cuda-driver --enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
> Thread model: posix
> gcc version 7.2.1 20170915 (Red Hat 7.2.1-2) (GCC)
> [root@jouet linux]# clang -v
> clang version 6.0.0 (http://llvm.org/git/clang.git 56cc8f8880db2ebc433eeb6b6a707c101467a186) (http://llvm.org/git/llvm.git 3656d83960a4f3fedf6d8f19043abf52379f78c3)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
> InstalledDir: /usr/local/bin
> Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/7
> Selected GCC installation: /usr/lib/gcc/x86_64-redhat-linux/7
> Candidate multilib: .;@m64
> Candidate multilib: 32;@m32
> Selected multilib: .;@m64
> [root@jouet linux]# perf test -v BPF
> 39: BPF filter :
> 39.1: Basic BPF filtering :
> --- start ---
> test child forked, pid 24304
> Kernel build dir is set to /lib/modules/4.15.0-rc6/build
> set env: KBUILD_DIR=/lib/modules/4.15.0-rc6/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=0x40f00
> set env: CLANG_EXEC=/usr/local/bin/clang
> set env: CLANG_OPTIONS=-xc
> 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: WORKING_DIR=/lib/modules/4.15.0-rc6/build
> set env: CLANG_SOURCE=-
> llvm compiling command template: echo '/*
> * bpf-script-example.c
> * Test basic LLVM building
> */
> #ifndef LINUX_VERSION_CODE
> # error Need LINUX_VERSION_CODE
> # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
> #endif
> #define BPF_ANY 0
> #define BPF_MAP_TYPE_ARRAY 2
> #define BPF_FUNC_map_lookup_elem 1
> #define BPF_FUNC_map_update_elem 2
>
> static void *(*bpf_map_lookup_elem)(void *map, void *key) =
> (void *) BPF_FUNC_map_lookup_elem;
> static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
> (void *) BPF_FUNC_map_update_elem;
>
> struct bpf_map_def {
> unsigned int type;
> unsigned int key_size;
> unsigned int value_size;
> unsigned int max_entries;
> };
>
> #define SEC(NAME) __attribute__((section(NAME), used))
> struct bpf_map_def SEC("maps") flip_table = {
> .type = BPF_MAP_TYPE_ARRAY,
> .key_size = sizeof(int),
> .value_size = sizeof(int),
> .max_entries = 1,
> };
>
> SEC("func=SyS_epoll_wait")
> int bpf_func__SyS_epoll_wait(void *ctx)
> {
> int ind =0;
> int *flag = bpf_map_lookup_elem(&flip_table, &ind);
> int new_flag;
> if (!flag)
> return 0;
> /* flip flag and store back */
> new_flag = !*flag;
> bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
> return new_flag;
> }
> char _license[] SEC("license") = "GPL";
> int _version SEC("version") = LINUX_VERSION_CODE;
> ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o -
> libbpf: loading object '[basic_bpf_test]' from buffer
> libbpf: section .strtab, size 120, link 0, flags 0, type=3
> libbpf: section .text, size 0, link 0, flags 6, type=1
> libbpf: section func=SyS_epoll_wait, size 192, link 0, flags 6, type=1
> libbpf: found program func=SyS_epoll_wait
> libbpf: section .relfunc=SyS_epoll_wait, size 32, link 8, flags 0, type=9
> libbpf: section maps, size 16, link 0, flags 3, type=1
> libbpf: section license, size 4, link 0, flags 3, type=1
> libbpf: license of [basic_bpf_test] is GPL
> libbpf: section version, size 4, link 0, flags 3, type=1
> libbpf: kernel version of [basic_bpf_test] is 40f00
> libbpf: section .symtab, size 168, link 1, flags 0, type=2
> libbpf: maps in [basic_bpf_test]: 1 maps in 16 bytes
> libbpf: map 0 is "flip_table"
> libbpf: collecting relocating info for: 'func=SyS_epoll_wait'
> libbpf: relocation: insn_idx=4
> libbpf: relocation: find map 0 (flip_table) for insn 4
> libbpf: relocation: insn_idx=17
> libbpf: relocation: find map 0 (flip_table) for insn 17
> bpf: config program 'func=SyS_epoll_wait'
> symbol:SyS_epoll_wait file:(null) line:0 offset:0 return:0 lazy:(null)
> bpf: config 'func=SyS_epoll_wait' is ok
> Looking at the vmlinux_path (8 entries long)
> Using /lib/modules/4.15.0-rc6/build/vmlinux for symbols
> Open Debuginfo file: /lib/modules/4.15.0-rc6/build/vmlinux
> Try to find probe point from debuginfo.
> Matched function: SyS_epoll_wait [2f40eb7]
> found inline addr: 0xffffffff812b6ff1
> Probe point found: compat_SyS_epoll_pwait+129
> found inline addr: 0xffffffff812b6de7
> Probe point found: SyS_epoll_pwait+135
> found inline addr: 0xffffffff812b6c80
> Probe point found: SyS_epoll_wait+0
> Found 3 probe_trace_events.
> Opening /sys/kernel/debug/tracing//kprobe_events write=1
> Writing event: p:perf_bpf_probe/func _text+2846705
> Writing event: p:perf_bpf_probe/func_1 _text+2846183
> Writing event: p:perf_bpf_probe/func_2 _text+2845824
> libbpf: create map flip_table: fd=3
> add bpf event perf_bpf_probe:func and attach bpf program 4
> registering plugin: /root/.traceevent/plugins/plugin_kvm.so
> registering plugin: /root/.traceevent/plugins/plugin_hrtimer.so
> registering plugin: /root/.traceevent/plugins/plugin_jbd2.so
> registering plugin: /root/.traceevent/plugins/plugin_kmem.so
> registering plugin: /root/.traceevent/plugins/plugin_scsi.so
> registering plugin: /root/.traceevent/plugins/plugin_sched_switch.so
> registering plugin: /root/.traceevent/plugins/plugin_function.so
> registering plugin: /root/.traceevent/plugins/plugin_xen.so
> registering plugin: /root/.traceevent/plugins/plugin_mac80211.so
> registering plugin: /root/.traceevent/plugins/plugin_cfg80211.so
> adding perf_bpf_probe:func
> adding perf_bpf_probe:func to 0x24e3850
> add bpf event perf_bpf_probe:func_1 and attach bpf program 4
> adding perf_bpf_probe:func_1
> adding perf_bpf_probe:func_1 to 0x1965020
> add bpf event perf_bpf_probe:func_2 and attach bpf program 4
> adding perf_bpf_probe:func_2
> adding perf_bpf_probe:func_2 to 0x19656a0
> mmap size 1052672B
> BPF filter result incorrect, expected 56, got 0 samples
> Opening /sys/kernel/debug/tracing//kprobe_events write=1
> Opening /sys/kernel/debug/tracing//uprobe_events write=1
> Parsing probe_events: p:perf_bpf_probe/func _text+2846705
> Group:perf_bpf_probe Event:func probe:p
> Parsing probe_events: p:perf_bpf_probe/func_1 _text+2846183
> Group:perf_bpf_probe Event:func_1 probe:p
> Parsing probe_events: p:perf_bpf_probe/func_2 _text+2845824
> Group:perf_bpf_probe Event:func_2 probe:p
> Writing event: -:perf_bpf_probe/func
> Opening /sys/kernel/debug/tracing//kprobe_events write=1
> Opening /sys/kernel/debug/tracing//uprobe_events write=1
> Parsing probe_events: p:perf_bpf_probe/func_1 _text+2846183
> Group:perf_bpf_probe Event:func_1 probe:p
> Parsing probe_events: p:perf_bpf_probe/func_2 _text+2845824
> Group:perf_bpf_probe Event:func_2 probe:p
> Writing event: -:perf_bpf_probe/func_1
> Opening /sys/kernel/debug/tracing//kprobe_events write=1
> Opening /sys/kernel/debug/tracing//uprobe_events write=1
> Parsing probe_events: p:perf_bpf_probe/func_2 _text+2845824
> Group:perf_bpf_probe Event:func_2 probe:p
> Writing event: -:perf_bpf_probe/func_2
> test child finished with -1
> ---- end ----
> BPF filter subtest 0: FAILED!
> 39.2: BPF pinning :
> --- force skipped ---
> BPF filter subtest 1: Skip
> 39.3: BPF prologue generation :
> --- force skipped ---
> BPF filter subtest 2: Skip
> 39.4: BPF relocation checker :
> --- force skipped ---
> BPF filter subtest 3: Skip
> [root@jouet linux]#
> [root@jouet linux]#


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