Commit 151936bf authored by Daniel T. Lee's avatar Daniel T. Lee Committed by Alexei Starovoitov
Browse files

samples: bpf: Replace attach_tracepoint() to attach() in xdp_redirect_cpu 



>From commit d7a18ea7 ("libbpf: Add generic bpf_program__attach()"),
for some BPF programs, it is now possible to attach BPF programs
with __attach() instead of explicitly calling __attach_<type>().

This commit refactors the __attach_tracepoint() with libbpf's generic
__attach() method. In addition, this refactors the logic of setting
the map FD to simplify the code. Also, the missing removal of
bpf_load.o in Makefile has been fixed.

Signed-off-by: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201010181734.1109-3-danieltimlee@gmail.com
parent 8ac91df6

samples/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -98,7 +98,7 @@ test_map_in_map-objs := test_map_in_map_user.o 
per_socket_stats_example-objs := cookie_uid_helper_example.o

xdp_redirect-objs := xdp_redirect_user.o

xdp_redirect_map-objs := xdp_redirect_map_user.o

xdp_redirect_cpu-objs := bpf_load.o xdp_redirect_cpu_user.o

xdp_redirect_cpu-objs := xdp_redirect_cpu_user.o

xdp_monitor-objs := xdp_monitor_user.o

xdp_rxq_info-objs := xdp_rxq_info_user.o

syscall_tp-objs := syscall_tp_user.o

samples/bpf/xdp_redirect_cpu_user.c

+72 −81
Original line number Diff line number Diff line
@@ -37,18 +37,35 @@ static __u32 prog_id; 


static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;

static int n_cpus;

static int cpu_map_fd;

static int rx_cnt_map_fd;

static int redirect_err_cnt_map_fd;

static int cpumap_enqueue_cnt_map_fd;

static int cpumap_kthread_cnt_map_fd;

static int cpus_available_map_fd;

static int cpus_count_map_fd;

static int cpus_iterator_map_fd;

static int exception_cnt_map_fd;



enum map_type {

	CPU_MAP,

	RX_CNT,

	REDIRECT_ERR_CNT,

	CPUMAP_ENQUEUE_CNT,

	CPUMAP_KTHREAD_CNT,

	CPUS_AVAILABLE,

	CPUS_COUNT,

	CPUS_ITERATOR,

	EXCEPTION_CNT,

};



static const char *const map_type_strings[] = {

	[CPU_MAP] = "cpu_map",

	[RX_CNT] = "rx_cnt",

	[REDIRECT_ERR_CNT] = "redirect_err_cnt",

	[CPUMAP_ENQUEUE_CNT] = "cpumap_enqueue_cnt",

	[CPUMAP_KTHREAD_CNT] = "cpumap_kthread_cnt",

	[CPUS_AVAILABLE] = "cpus_available",

	[CPUS_COUNT] = "cpus_count",

	[CPUS_ITERATOR] = "cpus_iterator",

	[EXCEPTION_CNT] = "exception_cnt",

};



#define NUM_TP 5

struct bpf_link *tp_links[NUM_TP] = { 0 };

#define NUM_MAP 9

struct bpf_link *tp_links[NUM_TP] = {};

static int map_fds[NUM_MAP];

static int tp_cnt = 0;



/* Exit return codes */
@@ -527,20 +544,20 @@ static void stats_collect(struct stats_record *rec) 
{

	int fd, i;



	fd = rx_cnt_map_fd;

	fd = map_fds[RX_CNT];

	map_collect_percpu(fd, 0, &rec->rx_cnt);



	fd = redirect_err_cnt_map_fd;

	fd = map_fds[REDIRECT_ERR_CNT];

	map_collect_percpu(fd, 1, &rec->redir_err);



	fd = cpumap_enqueue_cnt_map_fd;

	fd = map_fds[CPUMAP_ENQUEUE_CNT];

	for (i = 0; i < n_cpus; i++)

		map_collect_percpu(fd, i, &rec->enq[i]);



	fd = cpumap_kthread_cnt_map_fd;

	fd = map_fds[CPUMAP_KTHREAD_CNT];

	map_collect_percpu(fd, 0, &rec->kthread);



	fd = exception_cnt_map_fd;

	fd = map_fds[EXCEPTION_CNT];

	map_collect_percpu(fd, 0, &rec->exception);

}
@@ -565,7 +582,7 @@ static int create_cpu_entry(__u32 cpu, struct bpf_cpumap_val *value, 
	/* Add a CPU entry to cpumap, as this allocate a cpu entry in

	 * the kernel for the cpu.

	 */

	ret = bpf_map_update_elem(cpu_map_fd, &cpu, value, 0);

	ret = bpf_map_update_elem(map_fds[CPU_MAP], &cpu, value, 0);

	if (ret) {

		fprintf(stderr, "Create CPU entry failed (err:%d)\n", ret);

		exit(EXIT_FAIL_BPF);
@@ -574,21 +591,21 @@ static int create_cpu_entry(__u32 cpu, struct bpf_cpumap_val *value, 
	/* Inform bpf_prog's that a new CPU is available to select

	 * from via some control maps.

	 */

	ret = bpf_map_update_elem(cpus_available_map_fd, &avail_idx, &cpu, 0);

	ret = bpf_map_update_elem(map_fds[CPUS_AVAILABLE], &avail_idx, &cpu, 0);

	if (ret) {

		fprintf(stderr, "Add to avail CPUs failed\n");

		exit(EXIT_FAIL_BPF);

	}



	/* When not replacing/updating existing entry, bump the count */

	ret = bpf_map_lookup_elem(cpus_count_map_fd, &key, &curr_cpus_count);

	ret = bpf_map_lookup_elem(map_fds[CPUS_COUNT], &key, &curr_cpus_count);

	if (ret) {

		fprintf(stderr, "Failed reading curr cpus_count\n");

		exit(EXIT_FAIL_BPF);

	}

	if (new) {

		curr_cpus_count++;

		ret = bpf_map_update_elem(cpus_count_map_fd, &key,

		ret = bpf_map_update_elem(map_fds[CPUS_COUNT], &key,

					  &curr_cpus_count, 0);

		if (ret) {

			fprintf(stderr, "Failed write curr cpus_count\n");
@@ -612,7 +629,7 @@ static void mark_cpus_unavailable(void) 
	int ret, i;



	for (i = 0; i < n_cpus; i++) {

		ret = bpf_map_update_elem(cpus_available_map_fd, &i,

		ret = bpf_map_update_elem(map_fds[CPUS_AVAILABLE], &i,

					  &invalid_cpu, 0);

		if (ret) {

			fprintf(stderr, "Failed marking CPU unavailable\n");
@@ -665,68 +682,37 @@ static void stats_poll(int interval, bool use_separators, char *prog_name, 
	free_stats_record(prev);

}



static struct bpf_link * attach_tp(struct bpf_object *obj,

				   const char *tp_category,

				   const char* tp_name)

static int init_tracepoints(struct bpf_object *obj)

{

	struct bpf_program *prog;

	struct bpf_link *link;

	char sec_name[PATH_MAX];

	int len;



	len = snprintf(sec_name, PATH_MAX, "tracepoint/%s/%s",

		       tp_category, tp_name);

	if (len < 0)

		exit(EXIT_FAIL);

	bpf_object__for_each_program(prog, obj) {

		if (bpf_program__is_tracepoint(prog) != true)

			continue;



	prog = bpf_object__find_program_by_title(obj, sec_name);

	if (!prog) {

		fprintf(stderr, "ERR: finding progsec: %s\n", sec_name);

		exit(EXIT_FAIL_BPF);

		tp_links[tp_cnt] = bpf_program__attach(prog);

		if (libbpf_get_error(tp_links[tp_cnt])) {

			tp_links[tp_cnt] = NULL;

			return -EINVAL;

		}



	link = bpf_program__attach_tracepoint(prog, tp_category, tp_name);

	if (libbpf_get_error(link))

		exit(EXIT_FAIL_BPF);



	return link;

		tp_cnt++;

	}



static void init_tracepoints(struct bpf_object *obj) {

	tp_links[tp_cnt++] = attach_tp(obj, "xdp", "xdp_redirect_err");

	tp_links[tp_cnt++] = attach_tp(obj, "xdp", "xdp_redirect_map_err");

	tp_links[tp_cnt++] = attach_tp(obj, "xdp", "xdp_exception");

	tp_links[tp_cnt++] = attach_tp(obj, "xdp", "xdp_cpumap_enqueue");

	tp_links[tp_cnt++] = attach_tp(obj, "xdp", "xdp_cpumap_kthread");

	return 0;

}



static int init_map_fds(struct bpf_object *obj)

{

	/* Maps updated by tracepoints */

	redirect_err_cnt_map_fd =

		bpf_object__find_map_fd_by_name(obj, "redirect_err_cnt");

	exception_cnt_map_fd =

		bpf_object__find_map_fd_by_name(obj, "exception_cnt");

	cpumap_enqueue_cnt_map_fd =

		bpf_object__find_map_fd_by_name(obj, "cpumap_enqueue_cnt");

	cpumap_kthread_cnt_map_fd =

		bpf_object__find_map_fd_by_name(obj, "cpumap_kthread_cnt");



	/* Maps used by XDP */

	rx_cnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rx_cnt");

	cpu_map_fd = bpf_object__find_map_fd_by_name(obj, "cpu_map");

	cpus_available_map_fd =

		bpf_object__find_map_fd_by_name(obj, "cpus_available");

	cpus_count_map_fd = bpf_object__find_map_fd_by_name(obj, "cpus_count");

	cpus_iterator_map_fd =

		bpf_object__find_map_fd_by_name(obj, "cpus_iterator");



	if (cpu_map_fd < 0 || rx_cnt_map_fd < 0 ||

	    redirect_err_cnt_map_fd < 0 || cpumap_enqueue_cnt_map_fd < 0 ||

	    cpumap_kthread_cnt_map_fd < 0 || cpus_available_map_fd < 0 ||

	    cpus_count_map_fd < 0 || cpus_iterator_map_fd < 0 ||

	    exception_cnt_map_fd < 0)

	enum map_type type;



	for (type = 0; type < NUM_MAP; type++) {

		map_fds[type] =

			bpf_object__find_map_fd_by_name(obj,

							map_type_strings[type]);



		if (map_fds[type] < 0)

			return -ENOENT;

	}



	return 0;

}
@@ -795,13 +781,13 @@ int main(int argc, char **argv) 
	bool stress_mode = false;

	struct bpf_program *prog;

	struct bpf_object *obj;

	int err = EXIT_FAIL;

	char filename[256];

	int added_cpus = 0;

	int longindex = 0;

	int interval = 2;

	int add_cpu = -1;

	int opt, err;

	int prog_fd;

	int opt, prog_fd;

	int *cpu, i;

	__u32 qsize;
@@ -824,24 +810,29 @@ int main(int argc, char **argv) 
	}



	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))

		return EXIT_FAIL;

		return err;



	if (prog_fd < 0) {

		fprintf(stderr, "ERR: bpf_prog_load_xattr: %s\n",

			strerror(errno));

		return EXIT_FAIL;

		return err;

	}



	if (init_tracepoints(obj) < 0) {

		fprintf(stderr, "ERR: bpf_program__attach failed\n");

		return err;

	}

	init_tracepoints(obj);



	if (init_map_fds(obj) < 0) {

		fprintf(stderr, "bpf_object__find_map_fd_by_name failed\n");

		return EXIT_FAIL;

		return err;

	}

	mark_cpus_unavailable();



	cpu = malloc(n_cpus * sizeof(int));

	if (!cpu) {

		fprintf(stderr, "failed to allocate cpu array\n");

		return EXIT_FAIL;

		return err;

	}

	memset(cpu, 0, n_cpus * sizeof(int));
@@ -960,14 +951,12 @@ int main(int argc, char **argv) 
	prog = bpf_object__find_program_by_title(obj, prog_name);

	if (!prog) {

		fprintf(stderr, "bpf_object__find_program_by_title failed\n");

		err = EXIT_FAIL;

		goto out;

	}



	prog_fd = bpf_program__fd(prog);

	if (prog_fd < 0) {

		fprintf(stderr, "bpf_program__fd failed\n");

		err = EXIT_FAIL;

		goto out;

	}
@@ -986,6 +975,8 @@ int main(int argc, char **argv) 


	stats_poll(interval, use_separators, prog_name, mprog_name,

		   &value, stress_mode);



	err = EXIT_OK;

out:

	free(cpu);

	return err;

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