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samples/bpf: add a samples/bpf test for BPF_TASK_FD_QUERY

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This is mostly to test kprobe/uprobe which needs kernel headers.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2018-05-24 11:21:56 -07:00 committed by Alexei Starovoitov
parent 73bc4d9fc0
commit ecb96f7fe1
3 changed files with 405 additions and 0 deletions
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4
samples/bpf/Makefile
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@ -51,6 +51,7 @@ hostprogs-y += cpustat
hostprogs-y += xdp_adjust_tail
hostprogs-y += xdpsock
hostprogs-y += xdp_fwd
hostprogs-y += task_fd_query
# Libbpf dependencies
LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a
@ -105,6 +106,7 @@ cpustat-objs := bpf_load.o cpustat_user.o
xdp_adjust_tail-objs := xdp_adjust_tail_user.o
xdpsock-objs := bpf_load.o xdpsock_user.o
xdp_fwd-objs := bpf_load.o xdp_fwd_user.o
task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS)
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@ -160,6 +162,7 @@ always += cpustat_kern.o
always += xdp_adjust_tail_kern.o
always += xdpsock_kern.o
always += xdp_fwd_kern.o
always += task_fd_query_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
HOSTCFLAGS += -I$(srctree)/tools/lib/
@ -175,6 +178,7 @@ HOSTCFLAGS_offwaketime_user.o += -I$(srctree)/tools/lib/bpf/
HOSTCFLAGS_spintest_user.o += -I$(srctree)/tools/lib/bpf/
HOSTCFLAGS_trace_event_user.o += -I$(srctree)/tools/lib/bpf/
HOSTCFLAGS_sampleip_user.o += -I$(srctree)/tools/lib/bpf/
HOSTCFLAGS_task_fd_query_user.o += -I$(srctree)/tools/lib/bpf/
HOST_LOADLIBES += $(LIBBPF) -lelf
HOSTLOADLIBES_tracex4 += -lrt

19
samples/bpf/task_fd_query_kern.c Normal file
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@ -0,0 +1,19 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/version.h>
#include <linux/ptrace.h>
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
SEC("kprobe/blk_start_request")
int bpf_prog1(struct pt_regs *ctx)
{
return 0;
}
SEC("kretprobe/blk_account_io_completion")
int bpf_prog2(struct pt_regs *ctx)
{
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;

382
samples/bpf/task_fd_query_user.c Normal file
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@ -0,0 +1,382 @@
// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <stdbool.h>
#include <string.h>
#include <stdint.h>
#include <fcntl.h>
#include <linux/bpf.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "libbpf.h"
#include "bpf_load.h"
#include "bpf_util.h"
#include "perf-sys.h"
#include "trace_helpers.h"
#define CHECK_PERROR_RET(condition) ({ \
int __ret = !!(condition); \
if (__ret) { \
printf("FAIL: %s:\n", __func__); \
perror(" "); \
return -1; \
} \
})
#define CHECK_AND_RET(condition) ({ \
int __ret = !!(condition); \
if (__ret) \
return -1; \
})
static __u64 ptr_to_u64(void *ptr)
{
return (__u64) (unsigned long) ptr;
}
#define PMU_TYPE_FILE "/sys/bus/event_source/devices/%s/type"
static int bpf_find_probe_type(const char *event_type)
{
char buf[256];
int fd, ret;
ret = snprintf(buf, sizeof(buf), PMU_TYPE_FILE, event_type);
CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
fd = open(buf, O_RDONLY);
CHECK_PERROR_RET(fd < 0);
ret = read(fd, buf, sizeof(buf));
close(fd);
CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
errno = 0;
ret = (int)strtol(buf, NULL, 10);
CHECK_PERROR_RET(errno);
return ret;
}
#define PMU_RETPROBE_FILE "/sys/bus/event_source/devices/%s/format/retprobe"
static int bpf_get_retprobe_bit(const char *event_type)
{
char buf[256];
int fd, ret;
ret = snprintf(buf, sizeof(buf), PMU_RETPROBE_FILE, event_type);
CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
fd = open(buf, O_RDONLY);
CHECK_PERROR_RET(fd < 0);
ret = read(fd, buf, sizeof(buf));
close(fd);
CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
CHECK_PERROR_RET(strlen(buf) < strlen("config:"));
errno = 0;
ret = (int)strtol(buf + strlen("config:"), NULL, 10);
CHECK_PERROR_RET(errno);
return ret;
}
static int test_debug_fs_kprobe(int prog_fd_idx, const char *fn_name,
__u32 expected_fd_type)
{
__u64 probe_offset, probe_addr;
__u32 len, prog_id, fd_type;
char buf[256];
int err;
len = sizeof(buf);
err = bpf_task_fd_query(getpid(), event_fd[prog_fd_idx], 0, buf, &len,
&prog_id, &fd_type, &probe_offset,
&probe_addr);
if (err < 0) {
printf("FAIL: %s, for event_fd idx %d, fn_name %s\n",
__func__, prog_fd_idx, fn_name);
perror(" :");
return -1;
}
if (strcmp(buf, fn_name) != 0 ||
fd_type != expected_fd_type ||
probe_offset != 0x0 || probe_addr != 0x0) {
printf("FAIL: bpf_trace_event_query(event_fd[%d]):\n",
prog_fd_idx);
printf("buf: %s, fd_type: %u, probe_offset: 0x%llx,"
" probe_addr: 0x%llx\n",
buf, fd_type, probe_offset, probe_addr);
return -1;
}
return 0;
}
static int test_nondebug_fs_kuprobe_common(const char *event_type,
const char *name, __u64 offset, __u64 addr, bool is_return,
char *buf, __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
__u64 *probe_offset, __u64 *probe_addr)
{
int is_return_bit = bpf_get_retprobe_bit(event_type);
int type = bpf_find_probe_type(event_type);
struct perf_event_attr attr = {};
int fd;
if (type < 0 || is_return_bit < 0) {
printf("FAIL: %s incorrect type (%d) or is_return_bit (%d)\n",
__func__, type, is_return_bit);
return -1;
}
attr.sample_period = 1;
attr.wakeup_events = 1;
if (is_return)
attr.config |= 1 << is_return_bit;
if (name) {
attr.config1 = ptr_to_u64((void *)name);
attr.config2 = offset;
} else {
attr.config1 = 0;
attr.config2 = addr;
}
attr.size = sizeof(attr);
attr.type = type;
fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
CHECK_PERROR_RET(fd < 0);
CHECK_PERROR_RET(ioctl(fd, PERF_EVENT_IOC_ENABLE, 0) < 0);
CHECK_PERROR_RET(ioctl(fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) < 0);
CHECK_PERROR_RET(bpf_task_fd_query(getpid(), fd, 0, buf, buf_len,
prog_id, fd_type, probe_offset, probe_addr) < 0);
return 0;
}
static int test_nondebug_fs_probe(const char *event_type, const char *name,
__u64 offset, __u64 addr, bool is_return,
__u32 expected_fd_type,
__u32 expected_ret_fd_type,
char *buf, __u32 buf_len)
{
__u64 probe_offset, probe_addr;
__u32 prog_id, fd_type;
int err;
err = test_nondebug_fs_kuprobe_common(event_type, name,
offset, addr, is_return,
buf, &buf_len, &prog_id,
&fd_type, &probe_offset,
&probe_addr);
if (err < 0) {
printf("FAIL: %s, "
"for name %s, offset 0x%llx, addr 0x%llx, is_return %d\n",
__func__, name ? name : "", offset, addr, is_return);
perror(" :");
return -1;
}
if ((is_return && fd_type != expected_ret_fd_type) ||
(!is_return && fd_type != expected_fd_type)) {
printf("FAIL: %s, incorrect fd_type %u\n",
__func__, fd_type);
return -1;
}
if (name) {
if (strcmp(name, buf) != 0) {
printf("FAIL: %s, incorrect buf %s\n", __func__, buf);
return -1;
}
if (probe_offset != offset) {
printf("FAIL: %s, incorrect probe_offset 0x%llx\n",
__func__, probe_offset);
return -1;
}
} else {
if (buf_len != 0) {
printf("FAIL: %s, incorrect buf %p\n",
__func__, buf);
return -1;
}
if (probe_addr != addr) {
printf("FAIL: %s, incorrect probe_addr 0x%llx\n",
__func__, probe_addr);
return -1;
}
}
return 0;
}
static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
{
const char *event_type = "uprobe";
struct perf_event_attr attr = {};
char buf[256], event_alias[256];
__u64 probe_offset, probe_addr;
__u32 len, prog_id, fd_type;
int err, res, kfd, efd;
ssize_t bytes;
snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
event_type);
kfd = open(buf, O_WRONLY | O_APPEND, 0);
CHECK_PERROR_RET(kfd < 0);
res = snprintf(event_alias, sizeof(event_alias), "test_%d", getpid());
CHECK_PERROR_RET(res < 0 || res >= sizeof(event_alias));
res = snprintf(buf, sizeof(buf), "%c:%ss/%s %s:0x%lx",
is_return ? 'r' : 'p', event_type, event_alias,
binary_path, offset);
CHECK_PERROR_RET(res < 0 || res >= sizeof(buf));
CHECK_PERROR_RET(write(kfd, buf, strlen(buf)) < 0);
close(kfd);
kfd = -1;
snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
event_type, event_alias);
efd = open(buf, O_RDONLY, 0);
CHECK_PERROR_RET(efd < 0);
bytes = read(efd, buf, sizeof(buf));
CHECK_PERROR_RET(bytes <= 0 || bytes >= sizeof(buf));
close(efd);
buf[bytes] = '\0';
attr.config = strtol(buf, NULL, 0);
attr.type = PERF_TYPE_TRACEPOINT;
attr.sample_period = 1;
attr.wakeup_events = 1;
kfd = sys_perf_event_open(&attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
CHECK_PERROR_RET(kfd < 0);
CHECK_PERROR_RET(ioctl(kfd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) < 0);
CHECK_PERROR_RET(ioctl(kfd, PERF_EVENT_IOC_ENABLE, 0) < 0);
len = sizeof(buf);
err = bpf_task_fd_query(getpid(), kfd, 0, buf, &len,
&prog_id, &fd_type, &probe_offset,
&probe_addr);
if (err < 0) {
printf("FAIL: %s, binary_path %s\n", __func__, binary_path);
perror(" :");
return -1;
}
if ((is_return && fd_type != BPF_FD_TYPE_URETPROBE) ||
(!is_return && fd_type != BPF_FD_TYPE_UPROBE)) {
printf("FAIL: %s, incorrect fd_type %u\n", __func__,
fd_type);
return -1;
}
if (strcmp(binary_path, buf) != 0) {
printf("FAIL: %s, incorrect buf %s\n", __func__, buf);
return -1;
}
if (probe_offset != offset) {
printf("FAIL: %s, incorrect probe_offset 0x%llx\n", __func__,
probe_offset);
return -1;
}
close(kfd);
return 0;
}
int main(int argc, char **argv)
{
struct rlimit r = {1024*1024, RLIM_INFINITY};
extern char __executable_start;
char filename[256], buf[256];
__u64 uprobe_file_offset;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
if (setrlimit(RLIMIT_MEMLOCK, &r)) {
perror("setrlimit(RLIMIT_MEMLOCK)");
return 1;
}
if (load_kallsyms()) {
printf("failed to process /proc/kallsyms\n");
return 1;
}
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
/* test two functions in the corresponding *_kern.c file */
CHECK_AND_RET(test_debug_fs_kprobe(0, "blk_start_request",
BPF_FD_TYPE_KPROBE));
CHECK_AND_RET(test_debug_fs_kprobe(1, "blk_account_io_completion",
BPF_FD_TYPE_KRETPROBE));
/* test nondebug fs kprobe */
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x0, 0x0,
false, BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
buf, sizeof(buf)));
#ifdef __x86_64__
/* set a kprobe on "bpf_check + 0x5", which is x64 specific */
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x5, 0x0,
false, BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
buf, sizeof(buf)));
#endif
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x0, 0x0,
true, BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
buf, sizeof(buf)));
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
ksym_get_addr("bpf_check"), false,
BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
buf, sizeof(buf)));
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
ksym_get_addr("bpf_check"), false,
BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
NULL, 0));
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
ksym_get_addr("bpf_check"), true,
BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
buf, sizeof(buf)));
CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
ksym_get_addr("bpf_check"), true,
BPF_FD_TYPE_KPROBE,
BPF_FD_TYPE_KRETPROBE,
0, 0));
/* test nondebug fs uprobe */
/* the calculation of uprobe file offset is based on gcc 7.3.1 on x64
* and the default linker script, which defines __executable_start as
* the start of the .text section. The calculation could be different
* on different systems with different compilers. The right way is
* to parse the ELF file. We took a shortcut here.
*/
uprobe_file_offset = (__u64)main - (__u64)&__executable_start;
CHECK_AND_RET(test_nondebug_fs_probe("uprobe", (char *)argv[0],
uprobe_file_offset, 0x0, false,
BPF_FD_TYPE_UPROBE,
BPF_FD_TYPE_URETPROBE,
buf, sizeof(buf)));
CHECK_AND_RET(test_nondebug_fs_probe("uprobe", (char *)argv[0],
uprobe_file_offset, 0x0, true,
BPF_FD_TYPE_UPROBE,
BPF_FD_TYPE_URETPROBE,
buf, sizeof(buf)));
/* test debug fs uprobe */
CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
false));
CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
true));
return 0;
}