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perf tools: Enable passing event to BPF object
A new syntax is added to the parser so that the user can access predefined perf events in BPF objects. After this patch, BPF programs for perf are finally able to utilize bpf_perf_event_read() introduced in commit 35578d79 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU counter"). Test result: # cat test_bpf_map_2.c /************************ BEGIN **************************/ #include <uapi/linux/bpf.h> #define SEC(NAME) __attribute__((section(NAME), used)) struct bpf_map_def { unsigned int type; unsigned int key_size; unsigned int value_size; unsigned int max_entries; }; static int (*trace_printk)(const char *fmt, int fmt_size, ...) = (void *)BPF_FUNC_trace_printk; static int (*get_smp_processor_id)(void) = (void *)BPF_FUNC_get_smp_processor_id; static int (*perf_event_read)(struct bpf_map_def *, int) = (void *)BPF_FUNC_perf_event_read; struct bpf_map_def SEC("maps") pmu_map = { .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY, .key_size = sizeof(int), .value_size = sizeof(int), .max_entries = __NR_CPUS__, }; SEC("func_write=sys_write") int func_write(void *ctx) { unsigned long long val; char fmt[] = "sys_write: pmu=%llu\n"; val = perf_event_read(&pmu_map, get_smp_processor_id()); trace_printk(fmt, sizeof(fmt), val); return 0; } SEC("func_write_return=sys_write%return") int func_write_return(void *ctx) { unsigned long long val = 0; char fmt[] = "sys_write_return: pmu=%llu\n"; val = perf_event_read(&pmu_map, get_smp_processor_id()); trace_printk(fmt, sizeof(fmt), val); return 0; } char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; /************************* END ***************************/ Normal case: # echo "" > /sys/kernel/debug/tracing/trace # perf record -i -e cycles -e './test_bpf_map_2.c/map:pmu_map.event=cycles/' ls / [SNIP] [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.013 MB perf.data (7 samples) ] # cat /sys/kernel/debug/tracing/trace | grep ls ls-17066 [000] d... 938449.863301: : sys_write: pmu=1157327 ls-17066 [000] dN.. 938449.863342: : sys_write_return: pmu=1225218 ls-17066 [000] d... 938449.863349: : sys_write: pmu=1241922 ls-17066 [000] dN.. 938449.863369: : sys_write_return: pmu=1267445 Normal case (system wide): # echo "" > /sys/kernel/debug/tracing/trace # perf record -i -e cycles -e './test_bpf_map_2.c/map:pmu_map.event=cycles/' -a ^C[ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.811 MB perf.data (120 samples) ] # cat /sys/kernel/debug/tracing/trace | grep -v '18446744073709551594' | grep -v perf | head -n 20 [SNIP] # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | gmain-30828 [002] d... 2740551.068992: : sys_write: pmu=84373 gmain-30828 [002] d... 2740551.068992: : sys_write_return: pmu=87696 gmain-30828 [002] d... 2740551.068996: : sys_write: pmu=100658 gmain-30828 [002] d... 2740551.068997: : sys_write_return: pmu=102572 Error case 1: # perf record -e './test_bpf_map_2.c' ls / [SNIP] [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.014 MB perf.data ] # cat /sys/kernel/debug/tracing/trace | grep ls ls-17115 [007] d... 2724279.665625: : sys_write: pmu=18446744073709551614 ls-17115 [007] dN.. 2724279.665651: : sys_write_return: pmu=18446744073709551614 ls-17115 [007] d... 2724279.665658: : sys_write: pmu=18446744073709551614 ls-17115 [007] dN.. 2724279.665677: : sys_write_return: pmu=18446744073709551614 (18446744073709551614 is 0xfffffffffffffffe (-2)) Error case 2: # perf record -e cycles -e './test_bpf_map_2.c/map:pmu_map.event=evt/' -a event syntax error: '..ps:pmu_map.event=evt/' \___ Event not found for map setting Hint: Valid config terms: map:[<arraymap>].value=[value] map:[<eventmap>].event=[event] [SNIP] Error case 3: # ls /proc/2348/task/ 2348 2505 2506 2507 2508 # perf record -i -e cycles -e './test_bpf_map_2.c/map:pmu_map.event=cycles/' -p 2348 ERROR: Apply config to BPF failed: Cannot set event to BPF map in multi-thread tracing Error case 4: # perf record -e cycles -e './test_bpf_map_2.c/map:pmu_map.event=cycles/' ls / ERROR: Apply config to BPF failed: Doesn't support inherit event (Hint: use -i to turn off inherit) Error case 5: # perf record -i -e raw_syscalls:sys_enter -e './test_bpf_map_2.c/map:pmu_map.event=raw_syscalls:sys_enter/' ls ERROR: Apply config to BPF failed: Can only put raw, hardware and BPF output event into a BPF map Error case 6: # perf record -i -e './test_bpf_map_2.c/map:pmu_map.event=123/' ls / event syntax error: '.._map.event=123/' \___ Incorrect value type for map [SNIP] Signed-off-by:Wang Nan <wangnan0@huawei.com> Acked-by: