Messages in this thread | | | Subject | Re: perf test BPF failing on 4.15.0-rc6 | From | "Wangnan (F)" <> | Date | Wed, 3 Jan 2018 12:58:26 +0800 |
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And please check if the kprobe created by
$ perf probe -v SyS_epoll_wait
works for the test program used by this testcase:
#include <sys/epoll.h> #include <stdlib.h>
#define NR_ITERS 100
static int epoll_wait_loop(void) { int i;
/* Should fail NR_ITERS times */ for (i = 0; i < NR_ITERS; i++) epoll_wait(-(i + 1), NULL, 0, 0); return 0; }
int main() { epoll_wait_loop(); return 0; }
In my configuration it gives 100 samples:
$ sudo ./perf record -e probe:SyS_epoll_wait /tmp/a.out [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.016 MB perf.data (100 samples) ]
I guess in your configuration you would get 3 tracepoints, and can get 0 sample from them.
Thank you.
On 2018/1/3 12:42, Wangnan (F) wrote: > 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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