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Commit 3ced9b60 authored by Yonghong Song's avatar Yonghong Song Committed by Daniel Borkmann
Browse files

tools/bpf: add a bpf selftest for stacktrace 



Added a bpf selftest in test_progs at tools directory for stacktrace.
The test will populate a hashtable map and a stacktrace map
at the same time with the same key, stackid.
The user space will compare both maps, using BPF_MAP_LOOKUP_ELEM
command and BPF_MAP_GET_NEXT_KEY command, to ensure that both have
the same set of keys.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 16f07c55

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test 
TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \

	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \

	sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \

	test_l4lb_noinline.o test_xdp_noinline.o

	test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o



TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh \

	test_offload.py

tools/testing/selftests/bpf/test_progs.c

+127 −0
Original line number Diff line number Diff line
@@ -837,6 +837,132 @@ static void test_tp_attach_query(void) 
	free(query);

}



static int compare_map_keys(int map1_fd, int map2_fd)

{

	__u32 key, next_key;

	char val_buf[PERF_MAX_STACK_DEPTH * sizeof(__u64)];

	int err;



	err = bpf_map_get_next_key(map1_fd, NULL, &key);

	if (err)

		return err;

	err = bpf_map_lookup_elem(map2_fd, &key, val_buf);

	if (err)

		return err;



	while (bpf_map_get_next_key(map1_fd, &key, &next_key) == 0) {

		err = bpf_map_lookup_elem(map2_fd, &next_key, val_buf);

		if (err)

			return err;



		key = next_key;

	}

	if (errno != ENOENT)

		return -1;



	return 0;

}



static void test_stacktrace_map()

{

	int control_map_fd, stackid_hmap_fd, stackmap_fd;

	const char *file = "./test_stacktrace_map.o";

	int bytes, efd, err, pmu_fd, prog_fd;

	struct perf_event_attr attr = {};

	__u32 key, val, duration = 0;

	struct bpf_object *obj;

	char buf[256];



	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);

	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))

		goto out;



	/* Get the ID for the sched/sched_switch tracepoint */

	snprintf(buf, sizeof(buf),

		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");

	efd = open(buf, O_RDONLY, 0);

	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))

		goto close_prog;



	bytes = read(efd, buf, sizeof(buf));

	close(efd);

	if (CHECK(bytes <= 0 || bytes >= sizeof(buf),

		  "read", "bytes %d errno %d\n", bytes, errno))

		goto close_prog;



	/* Open the perf event and attach bpf progrram */

	attr.config = strtol(buf, NULL, 0);

	attr.type = PERF_TYPE_TRACEPOINT;

	attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;

	attr.sample_period = 1;

	attr.wakeup_events = 1;

	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,

			 0 /* cpu 0 */, -1 /* group id */,

			 0 /* flags */);

	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",

		  pmu_fd, errno))

		goto close_prog;



	err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);

	if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",

		  err, errno))

		goto close_pmu;



	err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);

	if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",

		  err, errno))

		goto disable_pmu;



	/* find map fds */

	control_map_fd = bpf_find_map(__func__, obj, "control_map");

	if (CHECK(control_map_fd < 0, "bpf_find_map control_map",

		  "err %d errno %d\n", err, errno))

		goto disable_pmu;



	stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");

	if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",

		  "err %d errno %d\n", err, errno))

		goto disable_pmu;



	stackmap_fd = bpf_find_map(__func__, obj, "stackmap");

	if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",

		  err, errno))

		goto disable_pmu;



	/* give some time for bpf program run */

	sleep(1);



	/* disable stack trace collection */

	key = 0;

	val = 1;

	bpf_map_update_elem(control_map_fd, &key, &val, 0);



	/* for every element in stackid_hmap, we can find a corresponding one

	 * in stackmap, and vise versa.

	 */

	err = compare_map_keys(stackid_hmap_fd, stackmap_fd);

	if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",

		  "err %d errno %d\n", err, errno))

		goto disable_pmu;



	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);

	if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",

		  "err %d errno %d\n", err, errno))

		; /* fall through */



disable_pmu:

	ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);



close_pmu:

	close(pmu_fd);



close_prog:

	bpf_object__close(obj);



out:

	return;

}



int main(void)

{

	struct rlimit rinf = { RLIM_INFINITY, RLIM_INFINITY };
@@ -852,6 +978,7 @@ int main(void) 
	test_pkt_md_access();

	test_obj_name();

	test_tp_attach_query();

	test_stacktrace_map();



	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);

	return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;

tools/testing/selftests/bpf/test_stacktrace_map.c

0 → 100644
+62 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2018 Facebook



#include <linux/bpf.h>

#include "bpf_helpers.h"



#ifndef PERF_MAX_STACK_DEPTH

#define PERF_MAX_STACK_DEPTH         127

#endif



struct bpf_map_def SEC("maps") control_map = {

	.type = BPF_MAP_TYPE_ARRAY,

	.key_size = sizeof(__u32),

	.value_size = sizeof(__u32),

	.max_entries = 1,

};



struct bpf_map_def SEC("maps") stackid_hmap = {

	.type = BPF_MAP_TYPE_HASH,

	.key_size = sizeof(__u32),

	.value_size = sizeof(__u32),

	.max_entries = 10000,

};



struct bpf_map_def SEC("maps") stackmap = {

	.type = BPF_MAP_TYPE_STACK_TRACE,

	.key_size = sizeof(__u32),

	.value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,

	.max_entries = 10000,

};



/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */

struct sched_switch_args {

	unsigned long long pad;

	char prev_comm[16];

	int prev_pid;

	int prev_prio;

	long long prev_state;

	char next_comm[16];

	int next_pid;

	int next_prio;

};



SEC("tracepoint/sched/sched_switch")

int oncpu(struct sched_switch_args *ctx)

{

	__u32 key = 0, val = 0, *value_p;



	value_p = bpf_map_lookup_elem(&control_map, &key);

	if (value_p && *value_p)

		return 0; /* skip if non-zero *value_p */



	/* The size of stackmap and stackid_hmap should be the same */

	key = bpf_get_stackid(ctx, &stackmap, 0);

	if ((int)key >= 0)

		bpf_map_update_elem(&stackid_hmap, &key, &val, 0);



	return 0;

}



char _license[] SEC("license") = "GPL";

__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */