bpf: add a test case for syscalls/sys_{enter|exit}_* tracepoints (1da236b6) · Commits · e / devices / android_kernel_fairphone_FP5

samples/bpf/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -39,6 +39,7 @@ hostprogs-y += per_socket_stats_example
		hostprogs-y += load_sock_ops
		hostprogs-y += xdp_redirect
		hostprogs-y += xdp_redirect_map
		hostprogs-y += syscall_tp

		# Libbpf dependencies
		LIBBPF := ../../tools/lib/bpf/bpf.o
		@@ -82,6 +83,7 @@ test_map_in_map-objs := bpf_load.o $(LIBBPF) test_map_in_map_user.o
		per_socket_stats_example-objs := $(LIBBPF) cookie_uid_helper_example.o
		xdp_redirect-objs := bpf_load.o $(LIBBPF) xdp_redirect_user.o
		xdp_redirect_map-objs := bpf_load.o $(LIBBPF) xdp_redirect_map_user.o
		syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o

		# Tell kbuild to always build the programs
		always := $(hostprogs-y)
		@@ -125,6 +127,7 @@ always += tcp_iw_kern.o
		always += tcp_clamp_kern.o
		always += xdp_redirect_kern.o
		always += xdp_redirect_map_kern.o
		always += syscall_tp_kern.o

		HOSTCFLAGS += -I$(objtree)/usr/include
		HOSTCFLAGS += -I$(srctree)/tools/lib/
		@@ -163,6 +166,7 @@ HOSTLOADLIBES_xdp_tx_iptunnel += -lelf
		HOSTLOADLIBES_test_map_in_map += -lelf
		HOSTLOADLIBES_xdp_redirect += -lelf
		HOSTLOADLIBES_xdp_redirect_map += -lelf
		HOSTLOADLIBES_syscall_tp += -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

samples/bpf/syscall_tp_kern.c

0 → 100644

+62 −0

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		/* Copyright (c) 2017 Facebook
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of version 2 of the GNU General Public
		* License as published by the Free Software Foundation.
		*/
		#include <uapi/linux/bpf.h>
		#include "bpf_helpers.h"

		struct syscalls_enter_open_args {
		unsigned long long unused;
		long syscall_nr;
		long filename_ptr;
		long flags;
		long mode;
		};

		struct syscalls_exit_open_args {
		unsigned long long unused;
		long syscall_nr;
		long ret;
		};

		struct bpf_map_def SEC("maps") enter_open_map = {
		.type = BPF_MAP_TYPE_ARRAY,
		.key_size = sizeof(u32),
		.value_size = sizeof(u32),
		.max_entries = 1,
		};

		struct bpf_map_def SEC("maps") exit_open_map = {
		.type = BPF_MAP_TYPE_ARRAY,
		.key_size = sizeof(u32),
		.value_size = sizeof(u32),
		.max_entries = 1,
		};

		static __always_inline void count(void *map)
		{
		u32 key = 0;
		u32 *value, init_val = 1;

		value = bpf_map_lookup_elem(map, &key);
		if (value)
		*value += 1;
		else
		bpf_map_update_elem(map, &key, &init_val, BPF_NOEXIST);
		}

		SEC("tracepoint/syscalls/sys_enter_open")
		int trace_enter_open(struct syscalls_enter_open_args *ctx)
		{
		count((void *)&enter_open_map);
		return 0;
		}

		SEC("tracepoint/syscalls/sys_exit_open")
		int trace_enter_exit(struct syscalls_exit_open_args *ctx)
		{
		count((void *)&exit_open_map);
		return 0;
		}

samples/bpf/syscall_tp_user.c

0 → 100644

+71 −0

Original line number	Diff line number	Diff line
		/* Copyright (c) 2017 Facebook
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of version 2 of the GNU General Public
		* License as published by the Free Software Foundation.
		*/
		#include <stdio.h>
		#include <unistd.h>
		#include <fcntl.h>
		#include <stdlib.h>
		#include <signal.h>
		#include <linux/bpf.h>
		#include <string.h>
		#include <linux/perf_event.h>
		#include <errno.h>
		#include <assert.h>
		#include <stdbool.h>
		#include <sys/resource.h>
		#include "libbpf.h"
		#include "bpf_load.h"

		/* This program verifies bpf attachment to tracepoint sys_enter_* and sys_exit_*.
		* This requires kernel CONFIG_FTRACE_SYSCALLS to be set.
		*/

		static void verify_map(int map_id)
		{
		__u32 key = 0;
		__u32 val;

		if (bpf_map_lookup_elem(map_id, &key, &val) != 0) {
		fprintf(stderr, "map_lookup failed: %s\n", strerror(errno));
		return;
		}
		if (val == 0)
		fprintf(stderr, "failed: map #%d returns value 0\n", map_id);
		}

		int main(int argc, char **argv)
		{
		struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
		char filename[256];
		int fd;

		setrlimit(RLIMIT_MEMLOCK, &r);
		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);

		if (load_bpf_file(filename)) {
		fprintf(stderr, "%s", bpf_log_buf);
		return 1;
		}

		/* current load_bpf_file has perf_event_open default pid = -1
		* and cpu = 0, which permits attached bpf execution on
		* all cpus for all pid's. bpf program execution ignores
		* cpu affinity.
		*/
		/* trigger some "open" operations */
		fd = open(filename, O_RDONLY);
		if (fd < 0) {
		fprintf(stderr, "open failed: %s\n", strerror(errno));
		return 1;
		}
		close(fd);

		/* verify the map */
		verify_map(map_fd[0]);
		verify_map(map_fd[1]);

		return 0;
		}