perf tools: Introduce bpf-output event
Commit a43eec304259a6c637f4014a6d4767159b6a3aa3 (bpf: introduce
bpf_perf_event_output() helper) add a helper to enable BPF program
output data to perf ring buffer through a new type of perf event
PERF_COUNT_SW_BPF_OUTPUT. This patch enable perf to create perf
event of that type. Now perf user can use following cmdline to
receive output data from BPF programs:
# ./perf record -a -e evt=bpf-output/no-inherit/ \
-e ./test_bpf_output.c/maps:channel.event=evt/ ls /
# ./perf script
perf 12927 [004] 355971.129276: 0 evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write
perf 12927 [004] 355971.129279: 0 evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write
...
Test result:
# cat ./test_bpf_output.c
/************************ BEGIN **************************/
#include <uapi/linux/bpf.h>
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))
static u64 (*ktime_get_ns)(void) =
(void *)BPF_FUNC_ktime_get_ns;
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_output)(void *, struct bpf_map_def *, int, void *, unsigned long) =
(void *)BPF_FUNC_perf_event_output;
struct bpf_map_def SEC("maps") channel = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(u32),
.max_entries = __NR_CPUS__,
};
SEC("func_write=sys_write")
int func_write(void *ctx)
{
struct {
u64 ktime;
int cpuid;
} __attribute__((packed)) output_data;
char error_data[] = "Error: failed to output: %d\n";
output_data.cpuid = get_smp_processor_id();
output_data.ktime = ktime_get_ns();
int err = perf_event_output(ctx, &channel, get_smp_processor_id(),
&output_data, sizeof(output_data));
if (err)
trace_printk(error_data, sizeof(error_data), err);
return 0;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
/************************ END ***************************/
# ./perf record -a -e evt=bpf-output/no-inherit/ \
-e ./test_bpf_output.c/maps:channel.event=evt/ ls /
# ./perf script | grep ls
ls 4085 [000] 2746114.230215: evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write (/lib/modules/4.3.0-rc4+/build/vmlinux)
ls 4085 [000] 2746114.230244: evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write (/lib/modules/4.3.0-rc4+/build/vmlinux)
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
4 files changed
