[v5,6/6] bpf: add new test test_many_kprobe

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 9b4a66e..ec92f35 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -42,6 +42,7 @@  hostprogs-y += xdp_redirect
 hostprogs-y += xdp_redirect_map
 hostprogs-y += xdp_monitor
 hostprogs-y += syscall_tp
+hostprogs-y += test_many_kprobe
 
 # Libbpf dependencies
 LIBBPF := ../../tools/lib/bpf/bpf.o
@@ -87,6 +88,7 @@  xdp_redirect-objs := bpf_load.o $(LIBBPF) xdp_redirect_user.o
 xdp_redirect_map-objs := bpf_load.o $(LIBBPF) xdp_redirect_map_user.o
 xdp_monitor-objs := bpf_load.o $(LIBBPF) xdp_monitor_user.o
 syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o
+test_many_kprobe-objs := bpf_load.o $(LIBBPF) test_many_kprobe_user.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
@@ -172,6 +174,7 @@  HOSTLOADLIBES_xdp_redirect += -lelf
 HOSTLOADLIBES_xdp_redirect_map += -lelf
 HOSTLOADLIBES_xdp_monitor += -lelf
 HOSTLOADLIBES_syscall_tp += -lelf
+HOSTLOADLIBES_test_many_kprobe += -lelf
 
 # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
 #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 86e3818..49f5be5 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -666,9 +666,8 @@  void read_trace_pipe(void)
 	}
 }
 
-#define MAX_SYMS 300000
-static struct ksym syms[MAX_SYMS];
-static int sym_cnt;
+struct ksym syms[MAX_SYMS];
+int sym_cnt;
 
 static int ksym_cmp(const void *p1, const void *p2)
 {
diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h
index 95d6be5..6c9d584 100644
--- a/samples/bpf/bpf_load.h
+++ b/samples/bpf/bpf_load.h
@@ -69,6 +69,10 @@  static inline __u64 ptr_to_u64(const void *ptr)
 	return (__u64) (unsigned long) ptr;
 }
 
+#define MAX_SYMS 300000
+extern struct ksym syms[MAX_SYMS];
+extern int sym_cnt;
+
 int load_kallsyms(void);
 struct ksym *ksym_search(long key);
 int set_link_xdp_fd(int ifindex, int fd, __u32 flags);
diff --git a/samples/bpf/test_many_kprobe_user.c b/samples/bpf/test_many_kprobe_user.c
new file mode 100644
index 0000000..6c111cf
--- /dev/null
+++ b/samples/bpf/test_many_kprobe_user.c
@@ -0,0 +1,186 @@ 
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017 Facebook
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <linux/version.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <time.h>
+#include "libbpf.h"
+#include "bpf_load.h"
+#include "perf-sys.h"
+
+#define MAX_KPROBES 1000
+
+#define DEBUGFS "/sys/kernel/debug/tracing/"
+
+int kprobes[MAX_KPROBES] = {0};
+int kprobe_count;
+int perf_event_fds[MAX_KPROBES];
+const char license[] = "GPL";
+
+static __u64 time_get_ns(void)
+{
+	struct timespec ts;
+
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts.tv_sec * 1000000000ull + ts.tv_nsec;
+}
+
+static int kprobe_api(char *func, void *addr, bool use_new_api)
+{
+	int efd;
+	struct perf_event_attr attr = {};
+	char buf[256];
+	int err, id;
+
+	attr.sample_type = PERF_SAMPLE_RAW;
+	attr.sample_period = 1;
+	attr.wakeup_events = 1;
+
+	if (use_new_api) {
+		attr.type = perf_kprobe_type;
+		if (func) {
+			attr.kprobe_func = ptr_to_u64(func);
+			attr.probe_offset = 0;
+		} else {
+			attr.kprobe_func = 0;
+			attr.kprobe_addr = ptr_to_u64(addr);
+		}
+	} else {
+		attr.type = PERF_TYPE_TRACEPOINT;
+		snprintf(buf, sizeof(buf),
+			 "echo 'p:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
+			 func, func);
+		err = system(buf);
+		if (err < 0) {
+			printf("failed to create kprobe '%s' error '%s'\n",
+			       func, strerror(errno));
+			return -1;
+		}
+
+		strcpy(buf, DEBUGFS);
+		strcat(buf, "events/kprobes/");
+		strcat(buf, func);
+		strcat(buf, "/id");
+		efd = open(buf, O_RDONLY, 0);
+		if (efd < 0) {
+			printf("failed to open event %s\n", func);
+			return -1;
+		}
+
+		err = read(efd, buf, sizeof(buf));
+		if (err < 0 || err >= sizeof(buf)) {
+			printf("read from '%s' failed '%s'\n", func,
+			       strerror(errno));
+			return -1;
+		}
+
+		close(efd);
+		buf[err] = 0;
+		id = atoi(buf);
+		attr.config = id;
+	}
+
+	attr.size = sizeof(attr);
+	efd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/,
+				  -1/*group_fd*/, 0);
+
+	return efd;
+}
+
+static int select_kprobes(void)
+{
+	int fd;
+	int i;
+
+	load_kallsyms();
+
+	kprobe_count = 0;
+	for (i = 0; i < sym_cnt; i++) {
+		if (strstr(syms[i].name, "."))
+			continue;
+		fd = kprobe_api(syms[i].name, NULL, false);
+		if (fd < 0)
+			continue;
+		close(fd);
+		kprobes[kprobe_count] = i;
+		if (++kprobe_count >= MAX_KPROBES)
+			break;
+	}
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int i;
+	__u64 start_time;
+
+	select_kprobes();
+
+	/* clean all trace_kprobe */
+	i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
+
+	/* test text based API */
+	start_time = time_get_ns();
+	for (i = 0; i < kprobe_count; i++)
+		perf_event_fds[i] = kprobe_api(syms[kprobes[i]].name,
+					       NULL, false);
+	printf("Creating %d kprobes with text-based API takes %f seconds\n",
+	       kprobe_count, (time_get_ns() - start_time) / 1000000000.0);
+
+	start_time = time_get_ns();
+	for (i = 0; i < kprobe_count; i++)
+		if (perf_event_fds[i] > 0)
+			close(perf_event_fds[i]);
+	i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
+	printf("Cleaning %d kprobes with text-based API takes %f seconds\n",
+	       kprobe_count, (time_get_ns() - start_time) / 1000000000.0);
+
+	get_perf_kprobe_type_id();
+	if (perf_kprobe_type == -1) {
+		printf("The kernel does support perf_kprobe.\n"
+		       "Existing...\n");
+		return 0;
+	}
+
+	/* test perf_kprobe API, with function names */
+	start_time = time_get_ns();
+	for (i = 0; i < kprobe_count; i++)
+		perf_event_fds[i] = kprobe_api(syms[kprobes[i]].name,
+					       NULL, true);
+	printf("Creating %d kprobes with perf_kprobe (function name) takes %f seconds\n",
+	       kprobe_count, (time_get_ns() - start_time) / 1000000000.0);
+
+	start_time = time_get_ns();
+	for (i = 0; i < kprobe_count; i++)
+		if (perf_event_fds[i] > 0)
+			close(perf_event_fds[i]);
+	printf("Cleaning %d kprobes with perf_kprobe (function name) takes %f seconds\n",
+	       kprobe_count, (time_get_ns() - start_time) / 1000000000.0);
+
+	/* test perf_kprobe API, with function address */
+	start_time = time_get_ns();
+	for (i = 0; i < kprobe_count; i++)
+		perf_event_fds[i] = kprobe_api(
+			NULL, (void *)(syms[kprobes[i]].addr), true);
+	printf("Creating %d kprobes with perf_kprobe (function addr) takes %f seconds\n",
+	       kprobe_count, (time_get_ns() - start_time) / 1000000000.0);
+
+	start_time = time_get_ns();
+	for (i = 0; i < kprobe_count; i++)
+		if (perf_event_fds[i] > 0)
+			close(perf_event_fds[i]);
+	printf("Cleaning %d kprobes with perf_kprobe (function addr) takes %f seconds\n",
+	       kprobe_count, (time_get_ns() - start_time) / 1000000000.0);
+	return 0;
+}