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samples: bpf: Refactor task_fd_query program with libbpf
This commit refactors the existing kprobe program with libbpf bpf loader. To attach bpf program, this uses generic bpf_program__attach() approach rather than using bpf_load's load_bpf_file(). To attach bpf to perf_event, instead of using previous ioctl method, this commit uses bpf_program__attach_perf_event since it manages the enable of perf_event and attach of BPF programs to it, which is much more intuitive way to achieve. Also, explicit close(fd) has been removed since event will be closed inside bpf_link__destroy() automatically. Furthermore, to prevent conflict of same named uprobe events, O_TRUNC flag has been used to clear 'uprobe_events' interface. Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20201124090310.24374-4-danieltimlee@gmail.com
This commit is contained in:
parent
d89af13c92
commit
4fe6641526
2 changed files with 75 additions and 28 deletions
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@ -107,7 +107,7 @@ xdp_adjust_tail-objs := xdp_adjust_tail_user.o
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xdpsock-objs := xdpsock_user.o
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xdpsock-objs := xdpsock_user.o
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xsk_fwd-objs := xsk_fwd.o
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xsk_fwd-objs := xsk_fwd.o
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xdp_fwd-objs := xdp_fwd_user.o
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xdp_fwd-objs := xdp_fwd_user.o
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task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS)
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task_fd_query-objs := task_fd_query_user.o $(TRACE_HELPERS)
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xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
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xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
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ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
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ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
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hbm-objs := hbm.o $(CGROUP_HELPERS)
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hbm-objs := hbm.o $(CGROUP_HELPERS)
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@ -15,12 +15,15 @@
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#include <sys/stat.h>
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#include <sys/stat.h>
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#include <linux/perf_event.h>
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#include <linux/perf_event.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include <bpf/libbpf.h>
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#include "bpf_load.h"
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#include "bpf_util.h"
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#include "bpf_util.h"
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#include "perf-sys.h"
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#include "perf-sys.h"
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#include "trace_helpers.h"
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#include "trace_helpers.h"
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static struct bpf_program *progs[2];
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static struct bpf_link *links[2];
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#define CHECK_PERROR_RET(condition) ({ \
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#define CHECK_PERROR_RET(condition) ({ \
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int __ret = !!(condition); \
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int __ret = !!(condition); \
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if (__ret) { \
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if (__ret) { \
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@ -86,21 +89,22 @@ static int bpf_get_retprobe_bit(const char *event_type)
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return ret;
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return ret;
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}
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}
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static int test_debug_fs_kprobe(int prog_fd_idx, const char *fn_name,
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static int test_debug_fs_kprobe(int link_idx, const char *fn_name,
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__u32 expected_fd_type)
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__u32 expected_fd_type)
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{
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{
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__u64 probe_offset, probe_addr;
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__u64 probe_offset, probe_addr;
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__u32 len, prog_id, fd_type;
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__u32 len, prog_id, fd_type;
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int err, event_fd;
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char buf[256];
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char buf[256];
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int err;
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len = sizeof(buf);
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len = sizeof(buf);
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err = bpf_task_fd_query(getpid(), event_fd[prog_fd_idx], 0, buf, &len,
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event_fd = bpf_link__fd(links[link_idx]);
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err = bpf_task_fd_query(getpid(), event_fd, 0, buf, &len,
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&prog_id, &fd_type, &probe_offset,
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&prog_id, &fd_type, &probe_offset,
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&probe_addr);
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&probe_addr);
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if (err < 0) {
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if (err < 0) {
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printf("FAIL: %s, for event_fd idx %d, fn_name %s\n",
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printf("FAIL: %s, for event_fd idx %d, fn_name %s\n",
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__func__, prog_fd_idx, fn_name);
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__func__, link_idx, fn_name);
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perror(" :");
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perror(" :");
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return -1;
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return -1;
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}
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}
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@ -108,7 +112,7 @@ static int test_debug_fs_kprobe(int prog_fd_idx, const char *fn_name,
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fd_type != expected_fd_type ||
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fd_type != expected_fd_type ||
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probe_offset != 0x0 || probe_addr != 0x0) {
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probe_offset != 0x0 || probe_addr != 0x0) {
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printf("FAIL: bpf_trace_event_query(event_fd[%d]):\n",
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printf("FAIL: bpf_trace_event_query(event_fd[%d]):\n",
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prog_fd_idx);
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link_idx);
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printf("buf: %s, fd_type: %u, probe_offset: 0x%llx,"
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printf("buf: %s, fd_type: %u, probe_offset: 0x%llx,"
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" probe_addr: 0x%llx\n",
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" probe_addr: 0x%llx\n",
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buf, fd_type, probe_offset, probe_addr);
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buf, fd_type, probe_offset, probe_addr);
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@ -125,12 +129,13 @@ static int test_nondebug_fs_kuprobe_common(const char *event_type,
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int is_return_bit = bpf_get_retprobe_bit(event_type);
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int is_return_bit = bpf_get_retprobe_bit(event_type);
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int type = bpf_find_probe_type(event_type);
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int type = bpf_find_probe_type(event_type);
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struct perf_event_attr attr = {};
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struct perf_event_attr attr = {};
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int fd;
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struct bpf_link *link;
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int fd, err = -1;
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if (type < 0 || is_return_bit < 0) {
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if (type < 0 || is_return_bit < 0) {
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printf("FAIL: %s incorrect type (%d) or is_return_bit (%d)\n",
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printf("FAIL: %s incorrect type (%d) or is_return_bit (%d)\n",
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__func__, type, is_return_bit);
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__func__, type, is_return_bit);
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return -1;
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return err;
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}
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}
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attr.sample_period = 1;
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attr.sample_period = 1;
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@ -149,14 +154,21 @@ static int test_nondebug_fs_kuprobe_common(const char *event_type,
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attr.type = type;
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attr.type = type;
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fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
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fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
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CHECK_PERROR_RET(fd < 0);
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link = bpf_program__attach_perf_event(progs[0], fd);
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if (libbpf_get_error(link)) {
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printf("ERROR: bpf_program__attach_perf_event failed\n");
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link = NULL;
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close(fd);
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goto cleanup;
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}
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CHECK_PERROR_RET(ioctl(fd, PERF_EVENT_IOC_ENABLE, 0) < 0);
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CHECK_PERROR_RET(ioctl(fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) < 0);
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CHECK_PERROR_RET(bpf_task_fd_query(getpid(), fd, 0, buf, buf_len,
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CHECK_PERROR_RET(bpf_task_fd_query(getpid(), fd, 0, buf, buf_len,
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prog_id, fd_type, probe_offset, probe_addr) < 0);
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prog_id, fd_type, probe_offset, probe_addr) < 0);
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err = 0;
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return 0;
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cleanup:
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bpf_link__destroy(link);
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return err;
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}
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}
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static int test_nondebug_fs_probe(const char *event_type, const char *name,
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static int test_nondebug_fs_probe(const char *event_type, const char *name,
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@ -215,17 +227,18 @@ static int test_nondebug_fs_probe(const char *event_type, const char *name,
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static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
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static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
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{
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{
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char buf[256], event_alias[sizeof("test_1234567890")];
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const char *event_type = "uprobe";
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const char *event_type = "uprobe";
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struct perf_event_attr attr = {};
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struct perf_event_attr attr = {};
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char buf[256], event_alias[sizeof("test_1234567890")];
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__u64 probe_offset, probe_addr;
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__u64 probe_offset, probe_addr;
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__u32 len, prog_id, fd_type;
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__u32 len, prog_id, fd_type;
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int err, res, kfd, efd;
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int err = -1, res, kfd, efd;
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struct bpf_link *link;
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ssize_t bytes;
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ssize_t bytes;
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snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
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snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
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event_type);
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event_type);
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kfd = open(buf, O_WRONLY | O_APPEND, 0);
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kfd = open(buf, O_WRONLY | O_TRUNC, 0);
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CHECK_PERROR_RET(kfd < 0);
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CHECK_PERROR_RET(kfd < 0);
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res = snprintf(event_alias, sizeof(event_alias), "test_%d", getpid());
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res = snprintf(event_alias, sizeof(event_alias), "test_%d", getpid());
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@ -254,10 +267,15 @@ static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
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attr.type = PERF_TYPE_TRACEPOINT;
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attr.type = PERF_TYPE_TRACEPOINT;
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attr.sample_period = 1;
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attr.sample_period = 1;
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attr.wakeup_events = 1;
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attr.wakeup_events = 1;
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kfd = sys_perf_event_open(&attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
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kfd = sys_perf_event_open(&attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
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CHECK_PERROR_RET(kfd < 0);
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link = bpf_program__attach_perf_event(progs[0], kfd);
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CHECK_PERROR_RET(ioctl(kfd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) < 0);
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if (libbpf_get_error(link)) {
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CHECK_PERROR_RET(ioctl(kfd, PERF_EVENT_IOC_ENABLE, 0) < 0);
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printf("ERROR: bpf_program__attach_perf_event failed\n");
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link = NULL;
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close(kfd);
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goto cleanup;
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}
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len = sizeof(buf);
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len = sizeof(buf);
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err = bpf_task_fd_query(getpid(), kfd, 0, buf, &len,
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err = bpf_task_fd_query(getpid(), kfd, 0, buf, &len,
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probe_offset);
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probe_offset);
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return -1;
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return -1;
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}
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}
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err = 0;
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close(kfd);
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cleanup:
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return 0;
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bpf_link__destroy(link);
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return err;
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}
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}
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int main(int argc, char **argv)
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int main(int argc, char **argv)
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extern char __executable_start;
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extern char __executable_start;
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char filename[256], buf[256];
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char filename[256], buf[256];
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__u64 uprobe_file_offset;
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__u64 uprobe_file_offset;
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struct bpf_program *prog;
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struct bpf_object *obj;
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int i = 0, err = -1;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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if (setrlimit(RLIMIT_MEMLOCK, &r)) {
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if (setrlimit(RLIMIT_MEMLOCK, &r)) {
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perror("setrlimit(RLIMIT_MEMLOCK)");
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perror("setrlimit(RLIMIT_MEMLOCK)");
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return 1;
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return err;
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}
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}
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if (load_kallsyms()) {
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if (load_kallsyms()) {
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printf("failed to process /proc/kallsyms\n");
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printf("failed to process /proc/kallsyms\n");
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return 1;
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return err;
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}
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}
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if (load_bpf_file(filename)) {
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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printf("%s", bpf_log_buf);
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obj = bpf_object__open_file(filename, NULL);
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return 1;
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if (libbpf_get_error(obj)) {
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fprintf(stderr, "ERROR: opening BPF object file failed\n");
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return err;
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}
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/* load BPF program */
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if (bpf_object__load(obj)) {
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fprintf(stderr, "ERROR: loading BPF object file failed\n");
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goto cleanup;
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}
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bpf_object__for_each_program(prog, obj) {
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progs[i] = prog;
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links[i] = bpf_program__attach(progs[i]);
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if (libbpf_get_error(links[i])) {
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fprintf(stderr, "ERROR: bpf_program__attach failed\n");
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links[i] = NULL;
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goto cleanup;
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}
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i++;
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}
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}
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/* test two functions in the corresponding *_kern.c file */
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/* test two functions in the corresponding *_kern.c file */
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@ -378,6 +419,12 @@ int main(int argc, char **argv)
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false));
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false));
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CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
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CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
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true));
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true));
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err = 0;
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return 0;
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cleanup:
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for (i--; i >= 0; i--)
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bpf_link__destroy(links[i]);
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bpf_object__close(obj);
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return err;
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}
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}
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