samples: bpf: Refactor hbm program with libbpf

This commit refactors the existing cgroup programs with libbpf
bpf loader. Since bpf_program__attach doesn't support cgroup program
attachment, this explicitly attaches cgroup bpf program with
bpf_program__attach_cgroup(bpf_prog, cg1).

Also, to change attach_type of bpf program, this uses libbpf's
bpf_program__set_expected_attach_type helper to switch EGRESS to
INGRESS. To keep bpf program attached to the cgroup hierarchy even
after the exit, this commit uses the BPF_LINK_PINNING to pin the link
attachment even after it is closed.

Besides, this program was broken due to the typo of BPF MAP definition.
But this commit solves the problem by fixing this from 'queue_stats' map
struct hvm_queue_stats -> hbm_queue_stats.

Fixes: 36b5d471135c ("selftests/bpf: samples/bpf: Split off legacy stuff from bpf_helpers.h")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201124090310.24374-2-danieltimlee@gmail.com

1 files changed, 59 insertions, 52 deletions

diff --git a/samples/bpf/hbm.c b/samples/bpf/hbm.c
index 400e741a56eb..b0c18efe7928 100644
--- a/samples/bpf/hbm.c
+++ b/samples/bpf/hbm.c
@@ -46,7 +46,6 @@
 #include <bpf/bpf.h>
 #include <getopt.h>
 
-#include "bpf_load.h"
 #include "bpf_rlimit.h"
 #include "cgroup_helpers.h"
 #include "hbm.h"
@@ -70,9 +69,9 @@ static void do_error(char *msg, bool errno_flag);
 
 #define DEBUGFS "/sys/kernel/debug/tracing/"
 
-struct bpf_object *obj;
-int bpfprog_fd;
-int cgroup_storage_fd;
+static struct bpf_program *bpf_prog;
+static struct bpf_object *obj;
+static int queue_stats_fd;
 
 static void read_trace_pipe2(void)
 {
@@ -121,56 +120,50 @@ static void do_error(char *msg, bool errno_flag)
 
 static int prog_load(char *prog)
 {
-	struct bpf_prog_load_attr prog_load_attr = {
-		.prog_type = BPF_PROG_TYPE_CGROUP_SKB,
-		.file = prog,
-		.expected_attach_type = BPF_CGROUP_INET_EGRESS,
-	};
-	int map_fd;
-	struct bpf_map *map;
-
-	int ret = 0;
-
-	if (access(prog, O_RDONLY) < 0) {
-		printf("Error accessing file %s: %s\n", prog, strerror(errno));
+	obj = bpf_object__open_file(prog, NULL);
+	if (libbpf_get_error(obj)) {
+		printf("ERROR: opening BPF object file failed\n");
 		return 1;
 	}
-	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &bpfprog_fd))
-		ret = 1;
-	if (!ret) {
-		map = bpf_object__find_map_by_name(obj, "queue_stats");
-		map_fd = bpf_map__fd(map);
-		if (map_fd < 0) {
-			printf("Map not found: %s\n", strerror(map_fd));
-			ret = 1;
-		}
+
+	/* load BPF program */
+	if (bpf_object__load(obj)) {
+		printf("ERROR: loading BPF object file failed\n");
+		goto err;
 	}
 
-	if (ret) {
-		printf("ERROR: bpf_prog_load_xattr failed for: %s\n", prog);
-		printf("  Output from verifier:\n%s\n------\n", bpf_log_buf);
-		ret = -1;
-	} else {
-		ret = map_fd;
+	bpf_prog = bpf_object__find_program_by_title(obj, "cgroup_skb/egress");
+	if (!bpf_prog) {
+		printf("ERROR: finding a prog in obj file failed\n");
+		goto err;
+	}
+
+	queue_stats_fd = bpf_object__find_map_fd_by_name(obj, "queue_stats");
+	if (queue_stats_fd < 0) {
+		printf("ERROR: finding a map in obj file failed\n");
+		goto err;
 	}
 
-	return ret;
+	return 0;
+
+err:
+	bpf_object__close(obj);
+	return 1;
 }
 
 static int run_bpf_prog(char *prog, int cg_id)
 {
-	int map_fd;
-	int rc = 0;
+	struct hbm_queue_stats qstats = {0};
+	char cg_dir[100], cg_pin_path[100];
+	struct bpf_link *link = NULL;
 	int key = 0;
 	int cg1 = 0;
-	int type = BPF_CGROUP_INET_EGRESS;
-	char cg_dir[100];
-	struct hbm_queue_stats qstats = {0};
+	int rc = 0;
 
 	sprintf(cg_dir, "/hbm%d", cg_id);
-	map_fd = prog_load(prog);
-	if (map_fd  == -1)
-		return 1;
+	rc = prog_load(prog);
+	if (rc != 0)
+		return rc;
 
 	if (setup_cgroup_environment()) {
 		printf("ERROR: setting cgroup environment\n");
@@ -190,16 +183,24 @@ static int run_bpf_prog(char *prog, int cg_id)
 	qstats.stats = stats_flag ? 1 : 0;
 	qstats.loopback = loopback_flag ? 1 : 0;
 	qstats.no_cn = no_cn_flag ? 1 : 0;
-	if (bpf_map_update_elem(map_fd, &key, &qstats, BPF_ANY)) {
+	if (bpf_map_update_elem(queue_stats_fd, &key, &qstats, BPF_ANY)) {
 		printf("ERROR: Could not update map element\n");
 		goto err;
 	}
 
 	if (!outFlag)
-		type = BPF_CGROUP_INET_INGRESS;
-	if (bpf_prog_attach(bpfprog_fd, cg1, type, 0)) {
-		printf("ERROR: bpf_prog_attach fails!\n");
-		log_err("Attaching prog");
+		bpf_program__set_expected_attach_type(bpf_prog, BPF_CGROUP_INET_INGRESS);
+
+	link = bpf_program__attach_cgroup(bpf_prog, cg1);
+	if (libbpf_get_error(link)) {
+		fprintf(stderr, "ERROR: bpf_program__attach_cgroup failed\n");
+		goto err;
+	}
+
+	sprintf(cg_pin_path, "/sys/fs/bpf/hbm%d", cg_id);
+	rc = bpf_link__pin(link, cg_pin_path);
+	if (rc < 0) {
+		printf("ERROR: bpf_link__pin failed: %d\n", rc);
 		goto err;
 	}
 
@@ -213,7 +214,7 @@ static int run_bpf_prog(char *prog, int cg_id)
 #define DELTA_RATE_CHECK 10000		/* in us */
 #define RATE_THRESHOLD 9500000000	/* 9.5 Gbps */
 
-		bpf_map_lookup_elem(map_fd, &key, &qstats);
+		bpf_map_lookup_elem(queue_stats_fd, &key, &qstats);
 		if (gettimeofday(&t0, NULL) < 0)
 			do_error("gettimeofday failed", true);
 		t_last = t0;
@@ -242,7 +243,7 @@ static int run_bpf_prog(char *prog, int cg_id)
 			fclose(fin);
 			printf("  new_eth_tx_bytes:%llu\n",
 			       new_eth_tx_bytes);
-			bpf_map_lookup_elem(map_fd, &key, &qstats);
+			bpf_map_lookup_elem(queue_stats_fd, &key, &qstats);
 			new_cg_tx_bytes = qstats.bytes_total;
 			delta_bytes = new_eth_tx_bytes - last_eth_tx_bytes;
 			last_eth_tx_bytes = new_eth_tx_bytes;
@@ -289,14 +290,14 @@ static int run_bpf_prog(char *prog, int cg_id)
 					rate = minRate;
 				qstats.rate = rate;
 			}
-			if (bpf_map_update_elem(map_fd, &key, &qstats, BPF_ANY))
+			if (bpf_map_update_elem(queue_stats_fd, &key, &qstats, BPF_ANY))
 				do_error("update map element fails", false);
 		}
 	} else {
 		sleep(dur);
 	}
 	// Get stats!
-	if (stats_flag && bpf_map_lookup_elem(map_fd, &key, &qstats)) {
+	if (stats_flag && bpf_map_lookup_elem(queue_stats_fd, &key, &qstats)) {
 		char fname[100];
 		FILE *fout;
 
@@ -394,14 +395,20 @@ static int run_bpf_prog(char *prog, int cg_id)
 
 	if (debugFlag)
 		read_trace_pipe2();
-	return rc;
+	goto cleanup;
+
 err:
 	rc = 1;
 
-	if (cg1)
+cleanup:
+	bpf_link__destroy(link);
+	bpf_object__close(obj);
+
+	if (cg1 != -1)
 		close(cg1);
-	cleanup_cgroup_environment();
 
+	if (rc != 0)
+		cleanup_cgroup_environment();
 	return rc;
 }