The bpf_program__attach of libbpf(using bpf_link) is much more intuitive
than the previous method using ioctl.
bpf_program__attach_perf_event manages the enable of perf_event and
attach of BPF programs to it, so there's no neeed to do this
directly with ioctl.
In addition, bpf_link provides consistency in the use of API because it
allows disable (detach, destroy) for multiple events to be treated as
one bpf_link__destroy. Also, bpf_link__destroy manages the close() of
perf_event fd.
This commit refactors samples that attach the bpf program to perf_event
by using libbbpf instead of ioctl. Also the bpf_load in the samples were
removed and migrated to use libbbpf API.
Signed-off-by: Daniel T. Lee <danieltimlee@xxxxxxxxx>
---
Changes in v2:
- check memory allocation is successful
- clean up allocated memory on error
Changes in v3:
- Improve pointer error check (IS_ERR())
- change to calloc for easier destroy of bpf_link
- remove perf_event fd list since bpf_link handles fd
- use newer bpf_object__{open/load} API instead of bpf_prog_load
- perf_event for _SC_NPROCESSORS_ONLN instead of _SC_NPROCESSORS_CONF
- find program with name explicitly instead of bpf_program__next
- unconditional bpf_link__destroy() on cleanup
Changes in v4:
- bpf_link *, bpf_object * set NULL on init & err for easier destroy
- close bpf object with bpf_object__close()
Changes in v5:
- on error, return error code with exit
samples/bpf/Makefile | 4 +-
samples/bpf/sampleip_user.c | 98 +++++++++++++++--------
samples/bpf/trace_event_user.c | 139 ++++++++++++++++++++++-----------
3 files changed, 159 insertions(+), 82 deletions(-)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index ff0061467dd3..424f6fe7ce38 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -88,8 +88,8 @@ xdp2-objs := xdp1_user.o
xdp_router_ipv4-objs := xdp_router_ipv4_user.o
test_current_task_under_cgroup-objs := bpf_load.o $(CGROUP_HELPERS) \
test_current_task_under_cgroup_user.o
-trace_event-objs := bpf_load.o trace_event_user.o $(TRACE_HELPERS)
-sampleip-objs := bpf_load.o sampleip_user.o $(TRACE_HELPERS)
+trace_event-objs := trace_event_user.o $(TRACE_HELPERS)
+sampleip-objs := sampleip_user.o $(TRACE_HELPERS)
tc_l2_redirect-objs := bpf_load.o tc_l2_redirect_user.o
lwt_len_hist-objs := bpf_load.o lwt_len_hist_user.o
xdp_tx_iptunnel-objs := xdp_tx_iptunnel_user.o
diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c
index b0f115f938bc..4372d2da2f9e 100644
--- a/samples/bpf/sampleip_user.c
+++ b/samples/bpf/sampleip_user.c
@@ -10,21 +10,23 @@
#include <errno.h>
#include <signal.h>
#include <string.h>
-#include <assert.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/bpf.h>
-#include <sys/ioctl.h>
+#include <bpf/bpf.h>
#include <bpf/libbpf.h>
-#include "bpf_load.h"
#include "perf-sys.h"
#include "trace_helpers.h"
+#define __must_check
+#include <linux/err.h>
+
#define DEFAULT_FREQ 99
#define DEFAULT_SECS 5
#define MAX_IPS 8192
#define PAGE_OFFSET 0xffff880000000000
+static int map_fd;
static int nr_cpus;
static void usage(void)
@@ -34,9 +36,10 @@ static void usage(void)
printf(" duration # sampling duration (seconds), default 5\n");
}
-static int sampling_start(int *pmu_fd, int freq)
+static int sampling_start(int freq, struct bpf_program *prog,
+ struct bpf_link *links[])
{
- int i;
+ int i, pmu_fd;
struct perf_event_attr pe_sample_attr = {
.type = PERF_TYPE_SOFTWARE,
@@ -47,26 +50,30 @@ static int sampling_start(int *pmu_fd, int freq)
};
for (i = 0; i < nr_cpus; i++) {
- pmu_fd[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
+ pmu_fd = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
-1 /* group_fd */, 0 /* flags */);
- if (pmu_fd[i] < 0) {
+ if (pmu_fd < 0) {
fprintf(stderr, "ERROR: Initializing perf sampling\n");
return 1;
}
- assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
- prog_fd[0]) == 0);
- assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
+ links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
+ if (IS_ERR(links[i])) {
+ fprintf(stderr, "ERROR: Attach perf event\n");
+ links[i] = NULL;
+ close(pmu_fd);
+ return 1;
+ }
}
return 0;
}
-static void sampling_end(int *pmu_fd)
+static void sampling_end(struct bpf_link *links[])
{
int i;
for (i = 0; i < nr_cpus; i++)
- close(pmu_fd[i]);
+ bpf_link__destroy(links[i]);
}
struct ipcount {
@@ -128,14 +135,17 @@ static void print_ip_map(int fd)
static void int_exit(int sig)
{
printf("\n");
- print_ip_map(map_fd[0]);
+ print_ip_map(map_fd);
exit(0);
}
int main(int argc, char **argv)
{
+ int opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS, error = 1;
+ struct bpf_object *obj = NULL;
+ struct bpf_program *prog;
+ struct bpf_link **links;
char filename[256];
- int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
/* process arguments */
while ((opt = getopt(argc, argv, "F:h")) != -1) {
@@ -163,38 +173,58 @@ int main(int argc, char **argv)
}
/* create perf FDs for each CPU */
- nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
- pmu_fd = malloc(nr_cpus * sizeof(int));
- if (pmu_fd == NULL) {
- fprintf(stderr, "ERROR: malloc of pmu_fd\n");
- return 1;
+ nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+ links = calloc(nr_cpus, sizeof(struct bpf_link *));
+ if (!links) {
+ fprintf(stderr, "ERROR: malloc of links\n");
+ goto cleanup;
}
- /* load BPF program */
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
- if (load_bpf_file(filename)) {
- fprintf(stderr, "ERROR: loading BPF program (errno %d):\n",
- errno);
- if (strcmp(bpf_log_buf, "") == 0)
- fprintf(stderr, "Try: ulimit -l unlimited\n");
- else
- fprintf(stderr, "%s", bpf_log_buf);
- return 1;
+ obj = bpf_object__open_file(filename, NULL);
+ if (IS_ERR(obj)) {
+ fprintf(stderr, "ERROR: opening BPF object file failed\n");
+ obj = NULL;
+ goto cleanup;
+ }
+
+ prog = bpf_object__find_program_by_name(obj, "do_sample");
+ if (!prog) {
+ fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
+ goto cleanup;
}
+
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "ERROR: loading BPF object file failed\n");
+ goto cleanup;
+ }
+
+ map_fd = bpf_object__find_map_fd_by_name(obj, "ip_map");
+ if (map_fd < 0) {
+ fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+ goto cleanup;
+ }
+
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
/* do sampling */
printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
freq, secs);
- if (sampling_start(pmu_fd, freq) != 0)
- return 1;
+ if (sampling_start(freq, prog, links) != 0)
+ goto cleanup;
+
sleep(secs);
- sampling_end(pmu_fd);
- free(pmu_fd);
+ error = 0;
+cleanup:
+ sampling_end(links);
/* output sample counts */
- print_ip_map(map_fd[0]);
+ if (!error)
+ print_ip_map(map_fd);
- return 0;
+ free(links);
+ bpf_object__close(obj);
+ return error;
}
diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
index 356171bc392b..f934544c994e 100644
--- a/samples/bpf/trace_event_user.c
+++ b/samples/bpf/trace_event_user.c
@@ -6,22 +6,25 @@
#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 <signal.h>
-#include <assert.h>
#include <errno.h>
#include <sys/resource.h>
+#include <bpf/bpf.h>
#include <bpf/libbpf.h>
-#include "bpf_load.h"
#include "perf-sys.h"
#include "trace_helpers.h"
+#define __must_check
+#include <linux/err.h>
+
#define SAMPLE_FREQ 50
+static int pid;
+/* counts, stackmap */
+static int map_fd[2];
+struct bpf_program *prog;
static bool sys_read_seen, sys_write_seen;
static void print_ksym(__u64 addr)
@@ -91,10 +94,10 @@ static void print_stack(struct key_t *key, __u64 count)
}
}
-static void int_exit(int sig)
+static void err_exit(int err)
{
- kill(0, SIGKILL);
- exit(0);
+ kill(pid, SIGKILL);
+ exit(err);
}
static void print_stacks(void)
@@ -102,7 +105,7 @@ static void print_stacks(void)
struct key_t key = {}, next_key;
__u64 value;
__u32 stackid = 0, next_id;
- int fd = map_fd[0], stack_map = map_fd[1];
+ int error = 1, fd = map_fd[0], stack_map = map_fd[1];
sys_read_seen = sys_write_seen = false;
while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
@@ -114,7 +117,7 @@ static void print_stacks(void)
printf("\n");
if (!sys_read_seen || !sys_write_seen) {
printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n");
- int_exit(0);
+ err_exit(error);
}
/* clear stack map */
@@ -136,43 +139,52 @@ static inline int generate_load(void)
static void test_perf_event_all_cpu(struct perf_event_attr *attr)
{
- int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
- int *pmu_fd = malloc(nr_cpus * sizeof(int));
- int i, error = 0;
+ int nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+ struct bpf_link **links = calloc(nr_cpus, sizeof(struct bpf_link *));
+ int i, pmu_fd, error = 1;
+
+ if (!links) {
+ printf("malloc of links failed\n");
+ goto err;
+ }
/* system wide perf event, no need to inherit */
attr->inherit = 0;
/* open perf_event on all cpus */
for (i = 0; i < nr_cpus; i++) {
- pmu_fd[i] = sys_perf_event_open(attr, -1, i, -1, 0);
- if (pmu_fd[i] < 0) {
+ pmu_fd = sys_perf_event_open(attr, -1, i, -1, 0);
+ if (pmu_fd < 0) {
printf("sys_perf_event_open failed\n");
- error = 1;
goto all_cpu_err;
}
- assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
- assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE) == 0);
+ links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
+ if (IS_ERR(links[i])) {
+ printf("bpf_program__attach_perf_event failed\n");
+ links[i] = NULL;
+ close(pmu_fd);
+ goto all_cpu_err;
+ }
}
- if (generate_load() < 0) {
- error = 1;
+ if (generate_load() < 0)
goto all_cpu_err;
- }
+
print_stacks();
+ error = 0;
all_cpu_err:
- for (i--; i >= 0; i--) {
- ioctl(pmu_fd[i], PERF_EVENT_IOC_DISABLE);
- close(pmu_fd[i]);
- }
- free(pmu_fd);
+ for (i--; i >= 0; i--)
+ bpf_link__destroy(links[i]);
+err:
+ free(links);
if (error)
- int_exit(0);
+ err_exit(error);
}
static void test_perf_event_task(struct perf_event_attr *attr)
{
- int pmu_fd, error = 0;
+ struct bpf_link *link = NULL;
+ int pmu_fd, error = 1;
/* per task perf event, enable inherit so the "dd ..." command can be traced properly.
* Enabling inherit will cause bpf_perf_prog_read_time helper failure.
@@ -183,21 +195,25 @@ static void test_perf_event_task(struct perf_event_attr *attr)
pmu_fd = sys_perf_event_open(attr, 0, -1, -1, 0);
if (pmu_fd < 0) {
printf("sys_perf_event_open failed\n");
- int_exit(0);
+ goto err;
}
- assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
- assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE) == 0);
-
- if (generate_load() < 0) {
- error = 1;
+ link = bpf_program__attach_perf_event(prog, pmu_fd);
+ if (IS_ERR(link)) {
+ printf("bpf_program__attach_perf_event failed\n");
+ link = NULL;
+ close(pmu_fd);
goto err;
}
+
+ if (generate_load() < 0)
+ goto err;
+
print_stacks();
+ error = 0;
err:
- ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
- close(pmu_fd);
+ bpf_link__destroy(link);
if (error)
- int_exit(0);
+ err_exit(error);
}
static void test_bpf_perf_event(void)
@@ -282,29 +298,60 @@ static void test_bpf_perf_event(void)
int main(int argc, char **argv)
{
struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+ struct bpf_object *obj = NULL;
char filename[256];
+ int error = 1;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
setrlimit(RLIMIT_MEMLOCK, &r);
- signal(SIGINT, int_exit);
- signal(SIGTERM, int_exit);
+ signal(SIGINT, err_exit);
+ signal(SIGTERM, err_exit);
if (load_kallsyms()) {
printf("failed to process /proc/kallsyms\n");
- return 1;
+ goto cleanup;
+ }
+
+ obj = bpf_object__open_file(filename, NULL);
+ if (IS_ERR(obj)) {
+ printf("opening BPF object file failed\n");
+ obj = NULL;
+ goto cleanup;
+ }
+
+ prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
+ if (!prog) {
+ printf("finding a prog in obj file failed\n");
+ goto cleanup;
+ }
+
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ printf("loading BPF object file failed\n");
+ goto cleanup;
}
- if (load_bpf_file(filename)) {
- printf("%s", bpf_log_buf);
- return 2;
+ map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
+ map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
+ if (map_fd[0] < 0 || map_fd[1] < 0) {
+ printf("finding a counts/stackmap map in obj file failed\n");
+ goto cleanup;
}
- if (fork() == 0) {
+ pid = fork();
+ if (pid == 0) {
read_trace_pipe();
return 0;
+ } else if (pid == -1) {
+ printf("couldn't spawn process\n");
+ goto cleanup;
}
+
test_bpf_perf_event();
- int_exit(0);
- return 0;
+ error = 0;
+
+cleanup:
+ bpf_object__close(obj);
+ err_exit(error);
}
--
2.25.1
