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: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/Makefile

@@ -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

+// 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

+// 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;
+}