samples: bpf: add bpf_perf_event_output example (39111695) · Commits · 戴 / test

samples/bpf/Makefile

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -13,6 +13,7 @@ hostprogs-y += tracex3
	hostprogs-y += tracex4		hostprogs-y += tracex4
	hostprogs-y += tracex5		hostprogs-y += tracex5
	hostprogs-y += tracex6		hostprogs-y += tracex6
			hostprogs-y += trace_output
	hostprogs-y += lathist		hostprogs-y += lathist

	test_verifier-objs := test_verifier.o libbpf.o		test_verifier-objs := test_verifier.o libbpf.o
	@@ -27,6 +28,7 @@ tracex3-objs := bpf_load.o libbpf.o tracex3_user.o
	tracex4-objs := bpf_load.o libbpf.o tracex4_user.o		tracex4-objs := bpf_load.o libbpf.o tracex4_user.o
	tracex5-objs := bpf_load.o libbpf.o tracex5_user.o		tracex5-objs := bpf_load.o libbpf.o tracex5_user.o
	tracex6-objs := bpf_load.o libbpf.o tracex6_user.o		tracex6-objs := bpf_load.o libbpf.o tracex6_user.o
			trace_output-objs := bpf_load.o libbpf.o trace_output_user.o
	lathist-objs := bpf_load.o libbpf.o lathist_user.o		lathist-objs := bpf_load.o libbpf.o lathist_user.o

	# Tell kbuild to always build the programs		# Tell kbuild to always build the programs
	@@ -40,6 +42,7 @@ always += tracex3_kern.o
	always += tracex4_kern.o		always += tracex4_kern.o
	always += tracex5_kern.o		always += tracex5_kern.o
	always += tracex6_kern.o		always += tracex6_kern.o
			always += trace_output_kern.o
	always += tcbpf1_kern.o		always += tcbpf1_kern.o
	always += lathist_kern.o		always += lathist_kern.o

	@@ -55,6 +58,7 @@ HOSTLOADLIBES_tracex3 += -lelf
	HOSTLOADLIBES_tracex4 += -lelf -lrt		HOSTLOADLIBES_tracex4 += -lelf -lrt
	HOSTLOADLIBES_tracex5 += -lelf		HOSTLOADLIBES_tracex5 += -lelf
	HOSTLOADLIBES_tracex6 += -lelf		HOSTLOADLIBES_tracex6 += -lelf
			HOSTLOADLIBES_trace_output += -lelf -lrt
	HOSTLOADLIBES_lathist += -lelf		HOSTLOADLIBES_lathist += -lelf

	# point this to your LLVM backend with bpf support		# point this to your LLVM backend with bpf support
	@@ -64,3 +68,6 @@ $(obj)/%.o: $(src)/%.c
	clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \		clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
	-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \		-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
	-O2 -emit-llvm -c $< -o -\| $(LLC) -march=bpf -filetype=obj -o $@		-O2 -emit-llvm -c $< -o -\| $(LLC) -march=bpf -filetype=obj -o $@
			clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
			-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
			-O2 -emit-llvm -c $< -o -\| $(LLC) -march=bpf -filetype=asm -o $@.s

samples/bpf/bpf_helpers.h

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -37,6 +37,8 @@ static int (bpf_clone_redirect)(void ctx, int ifindex, int flags) =
	(void *) BPF_FUNC_clone_redirect;		(void *) BPF_FUNC_clone_redirect;
	static int (*bpf_redirect)(int ifindex, int flags) =		static int (*bpf_redirect)(int ifindex, int flags) =
	(void *) BPF_FUNC_redirect;		(void *) BPF_FUNC_redirect;
			static int (bpf_perf_event_output)(void ctx, void map, int index, void data, int size) =
			(void *) BPF_FUNC_perf_event_output;

	/* llvm builtin functions that eBPF C program may use to		/* llvm builtin functions that eBPF C program may use to
	* emit BPF_LD_ABS and BPF_LD_IND instructions		* emit BPF_LD_ABS and BPF_LD_IND instructions

samples/bpf/trace_output_kern.c

0 → 100644

+31 −0

Original line number	Original line	Diff line number	Diff line
			#include <linux/ptrace.h>
			#include <linux/version.h>
			#include <uapi/linux/bpf.h>
			#include "bpf_helpers.h"

			struct bpf_map_def SEC("maps") my_map = {
			.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
			.key_size = sizeof(int),
			.value_size = sizeof(u32),
			.max_entries = 2,
			};

			SEC("kprobe/sys_write")
			int bpf_prog1(struct pt_regs *ctx)
			{
			struct S {
			u64 pid;
			u64 cookie;
			} data;

			memset(&data, 0, sizeof(data));
			data.pid = bpf_get_current_pid_tgid();
			data.cookie = 0x12345678;

			bpf_perf_event_output(ctx, &my_map, 0, &data, sizeof(data));

			return 0;
			}

			char _license[] SEC("license") = "GPL";
			u32 _version SEC("version") = LINUX_VERSION_CODE;

samples/bpf/trace_output_user.c

0 → 100644

+196 −0

Original line number	Original line	Diff line number	Diff line
			/* This program is free software; you can redistribute it and/or
			* modify it under the terms of version 2 of the GNU General Public
			* License as published by the Free Software Foundation.
			*/
			#include <stdio.h>
			#include <unistd.h>
			#include <stdlib.h>
			#include <stdbool.h>
			#include <string.h>
			#include <fcntl.h>
			#include <poll.h>
			#include <sys/ioctl.h>
			#include <linux/perf_event.h>
			#include <linux/bpf.h>
			#include <errno.h>
			#include <assert.h>
			#include <sys/syscall.h>
			#include <sys/ioctl.h>
			#include <sys/mman.h>
			#include <time.h>
			#include <signal.h>
			#include "libbpf.h"
			#include "bpf_load.h"

			static int pmu_fd;

			int page_size;
			int page_cnt = 8;
			volatile struct perf_event_mmap_page *header;

			typedef void (print_fn)(void data, int size);

			static int perf_event_mmap(int fd)
			{
			void *base;
			int mmap_size;

			page_size = getpagesize();
			mmap_size = page_size * (page_cnt + 1);

			base = mmap(NULL, mmap_size, PROT_READ \| PROT_WRITE, MAP_SHARED, fd, 0);
			if (base == MAP_FAILED) {
			printf("mmap err\n");
			return -1;
			}

			header = base;
			return 0;
			}

			static int perf_event_poll(int fd)
			{
			struct pollfd pfd = { .fd = fd, .events = POLLIN };

			return poll(&pfd, 1, 1000);
			}

			struct perf_event_sample {
			struct perf_event_header header;
			__u32 size;
			char data[];
			};

			void perf_event_read(print_fn fn)
			{
			__u64 data_tail = header->data_tail;
			__u64 data_head = header->data_head;
			__u64 buffer_size = page_cnt * page_size;
			void base, begin, *end;
			char buf[256];

			asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
			if (data_head == data_tail)
			return;

			base = ((char *)header) + page_size;

			begin = base + data_tail % buffer_size;
			end = base + data_head % buffer_size;

			while (begin != end) {
			struct perf_event_sample *e;

			e = begin;
			if (begin + e->header.size > base + buffer_size) {
			long len = base + buffer_size - begin;

			assert(len < e->header.size);
			memcpy(buf, begin, len);
			memcpy(buf + len, base, e->header.size - len);
			e = (void *) buf;
			begin = base + e->header.size - len;
			} else if (begin + e->header.size == base + buffer_size) {
			begin = base;
			} else {
			begin += e->header.size;
			}

			if (e->header.type == PERF_RECORD_SAMPLE) {
			fn(e->data, e->size);
			} else if (e->header.type == PERF_RECORD_LOST) {
			struct {
			struct perf_event_header header;
			__u64 id;
			__u64 lost;
			} lost = (void ) e;
			printf("lost %lld events\n", lost->lost);
			} else {
			printf("unknown event type=%d size=%d\n",
			e->header.type, e->header.size);
			}
			}

			__sync_synchronize(); /* smp_mb() */
			header->data_tail = data_head;
			}

			static __u64 time_get_ns(void)
			{
			struct timespec ts;

			clock_gettime(CLOCK_MONOTONIC, &ts);
			return ts.tv_sec * 1000000000ull + ts.tv_nsec;
			}

			static __u64 start_time;

			#define MAX_CNT 100000ll

			static void print_bpf_output(void *data, int size)
			{
			static __u64 cnt;
			struct {
			__u64 pid;
			__u64 cookie;
			} *e = data;

			if (e->cookie != 0x12345678) {
			printf("BUG pid %llx cookie %llx sized %d\n",
			e->pid, e->cookie, size);
			kill(0, SIGINT);
			}

			cnt++;

			if (cnt == MAX_CNT) {
			printf("recv %lld events per sec\n",
			MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
			kill(0, SIGINT);
			}
			}

			static void test_bpf_perf_event(void)
			{
			struct perf_event_attr attr = {
			.sample_type = PERF_SAMPLE_RAW,
			.type = PERF_TYPE_SOFTWARE,
			.config = PERF_COUNT_SW_BPF_OUTPUT,
			};
			int key = 0;

			pmu_fd = perf_event_open(&attr, -1/pid/, 0/cpu/, -1/group_fd/, 0);

			assert(pmu_fd >= 0);
			assert(bpf_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0);
			ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
			}

			int main(int argc, char **argv)
			{
			char filename[256];
			FILE *f;

			snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);

			if (load_bpf_file(filename)) {
			printf("%s", bpf_log_buf);
			return 1;
			}

			test_bpf_perf_event();

			if (perf_event_mmap(pmu_fd) < 0)
			return 1;

			f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
			(void) f;

			start_time = time_get_ns();
			for (;;) {
			perf_event_poll(pmu_fd);
			perf_event_read(print_bpf_output);
			}

			return 0;
			}

Admin message