samples: bpf: add bpf_perf_event_output example (39111695) · Commits · e / devices / android_kernel_teracube_2e

samples/bpf/Makefile

+7 −0

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

		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
		tracex5-objs := bpf_load.o libbpf.o tracex5_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

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

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

		# point this to your LLVM backend with bpf support
		@@ -64,3 +68,6 @@ $(obj)/%.o: $(src)/%.c
		clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
		-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
		-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	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;
		static int (*bpf_redirect)(int ifindex, int flags) =
		(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
		* emit BPF_LD_ABS and BPF_LD_IND instructions

samples/bpf/trace_output_kern.c

0 → 100644

+31 −0

Original line number	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	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;
		}