Commit 763af200 authored by Daniel T. Lee's avatar Daniel T. Lee Committed by Andrii Nakryiko
Browse files

samples: bpf: Refactor ibumad program with libbpf 



This commit refactors the existing ibumad program with libbpf bpf
loader. Attach/detach of Tracepoint bpf programs has been managed
with the generic bpf_program__attach() and bpf_link__destroy() from
the libbpf.

Also, instead of using the previous BPF MAP definition, this commit
refactors ibumad MAP definition with the new BTF-defined MAP format.

To verify that this bpf program works without an infiniband device,
try loading ib_umad kernel module and test the program as follows:

    # modprobe ib_umad
    # ./ibumad

Moreover, TRACE_HELPERS has been removed from the Makefile since it is
not used on this program.

Signed-off-by: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201124090310.24374-5-danieltimlee@gmail.com
parent 4fe66415

samples/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -109,7 +109,7 @@ xsk_fwd-objs := xsk_fwd.o 
xdp_fwd-objs := xdp_fwd_user.o

task_fd_query-objs := task_fd_query_user.o $(TRACE_HELPERS)

xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)

ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)

ibumad-objs := ibumad_user.o

hbm-objs := hbm.o $(CGROUP_HELPERS)



# Tell kbuild to always build the programs

samples/bpf/ibumad_kern.c

+13 −13
Original line number Diff line number Diff line
@@ -16,19 +16,19 @@ 
#include <bpf/bpf_helpers.h>





struct bpf_map_def SEC("maps") read_count = {

	.type        = BPF_MAP_TYPE_ARRAY,

	.key_size    = sizeof(u32), /* class; u32 required */

	.value_size  = sizeof(u64), /* count of mads read */

	.max_entries = 256, /* Room for all Classes */

};



struct bpf_map_def SEC("maps") write_count = {

	.type        = BPF_MAP_TYPE_ARRAY,

	.key_size    = sizeof(u32), /* class; u32 required */

	.value_size  = sizeof(u64), /* count of mads written */

	.max_entries = 256, /* Room for all Classes */

};

struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, u32); /* class; u32 required */

	__type(value, u64); /* count of mads read */

	__uint(max_entries, 256); /* Room for all Classes */

} read_count SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, u32); /* class; u32 required */

	__type(value, u64); /* count of mads written */

	__uint(max_entries, 256); /* Room for all Classes */

} write_count SEC(".maps");



#undef DEBUG

#ifndef DEBUG

samples/bpf/ibumad_user.c

+54 −17
Original line number Diff line number Diff line
@@ -23,10 +23,15 @@ 
#include <getopt.h>

#include <net/if.h>



#include "bpf_load.h"

#include <bpf/bpf.h>

#include "bpf_util.h"

#include <bpf/libbpf.h>



static struct bpf_link *tp_links[3];

static struct bpf_object *obj;

static int map_fd[2];

static int tp_cnt;



static void dump_counts(int fd)

{

	__u32 key;
@@ -53,6 +58,11 @@ static void dump_all_counts(void) 
static void dump_exit(int sig)

{

	dump_all_counts();

	/* Detach tracepoints */

	while (tp_cnt)

		bpf_link__destroy(tp_links[--tp_cnt]);



	bpf_object__close(obj);

	exit(0);

}
@@ -73,19 +83,11 @@ static void usage(char *cmd) 


int main(int argc, char **argv)

{

	struct bpf_program *prog;

	unsigned long delay = 5;

	char filename[256];

	int longindex = 0;

	int opt;

	char bpf_file[256];



	/* Create the eBPF kernel code path name.

	 * This follows the pattern of all of the other bpf samples

	 */

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



	/* Do one final dump when exiting */

	signal(SIGINT, dump_exit);

	signal(SIGTERM, dump_exit);

	int opt, err = -1;



	while ((opt = getopt_long(argc, argv, "hd:rSw",

				  long_options, &longindex)) != -1) {
@@ -107,16 +109,51 @@ int main(int argc, char **argv) 
		}

	}



	if (load_bpf_file(bpf_file)) {

		fprintf(stderr, "ERROR: failed to load eBPF from file : %s\n",

			bpf_file);

		return 1;

	/* Do one final dump when exiting */

	signal(SIGINT, dump_exit);

	signal(SIGTERM, dump_exit);



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

	obj = bpf_object__open_file(filename, NULL);

	if (libbpf_get_error(obj)) {

		fprintf(stderr, "ERROR: opening BPF object file failed\n");

		return err;

	}



	/* load BPF program */

	if (bpf_object__load(obj)) {

		fprintf(stderr, "ERROR: loading BPF object file failed\n");

		goto cleanup;

	}



	map_fd[0] = bpf_object__find_map_fd_by_name(obj, "read_count");

	map_fd[1] = bpf_object__find_map_fd_by_name(obj, "write_count");

	if (map_fd[0] < 0 || map_fd[1] < 0) {

		fprintf(stderr, "ERROR: finding a map in obj file failed\n");

		goto cleanup;

	}



	bpf_object__for_each_program(prog, obj) {

		tp_links[tp_cnt] = bpf_program__attach(prog);

		if (libbpf_get_error(tp_links[tp_cnt])) {

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

			tp_links[tp_cnt] = NULL;

			goto cleanup;

		}

		tp_cnt++;

	}



	while (1) {

		sleep(delay);

		dump_all_counts();

	}

	err = 0;



cleanup:

	/* Detach tracepoints */

	while (tp_cnt)

		bpf_link__destroy(tp_links[--tp_cnt]);



	return 0;

	bpf_object__close(obj);

	return err;

}