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Commit ecb96f7f authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

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



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

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 73bc4d9f

samples/bpf/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -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

samples/bpf/task_fd_query_kern.c

0 → 100644
+19 −0
Original line number Diff line number Diff line 
// 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;

samples/bpf/task_fd_query_user.c

0 → 100644
+382 −0
Original line number Diff line number Diff line 
// 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;

}