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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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/types.h>#include <sys/stat.h>#include <linux/perf_event.h>
#include <bpf/bpf.h>#include <bpf/libbpf.h>#include "bpf_util.h"#include "perf-sys.h"#include "trace_helpers.h"
static struct bpf_program *progs[2];static struct bpf_link *links[2];
#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 link_idx, const char *fn_name, __u32 expected_fd_type){ __u64 probe_offset, probe_addr; __u32 len, prog_id, fd_type; int err, event_fd; char buf[256];
len = sizeof(buf); event_fd = bpf_link__fd(links[link_idx]); err = bpf_task_fd_query(getpid(), event_fd, 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__, link_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", link_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 = {}; struct bpf_link *link; int fd, err = -1;
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 err; }
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); link = bpf_program__attach_perf_event(progs[0], fd); if (libbpf_get_error(link)) { printf("ERROR: bpf_program__attach_perf_event failed\n"); link = NULL; close(fd); goto cleanup; }
CHECK_PERROR_RET(bpf_task_fd_query(getpid(), fd, 0, buf, buf_len, prog_id, fd_type, probe_offset, probe_addr) < 0); err = 0;
cleanup: bpf_link__destroy(link); return err;}
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){ char buf[256], event_alias[sizeof("test_1234567890")]; const char *event_type = "uprobe"; struct perf_event_attr attr = {}; __u64 probe_offset, probe_addr; __u32 len, prog_id, fd_type; int err = -1, res, kfd, efd; struct bpf_link *link; ssize_t bytes;
snprintf(buf, sizeof(buf), "/sys/kernel/tracing/%s_events", event_type); kfd = open(buf, O_WRONLY | O_TRUNC, 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/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); link = bpf_program__attach_perf_event(progs[0], kfd); if (libbpf_get_error(link)) { printf("ERROR: bpf_program__attach_perf_event failed\n"); link = NULL; close(kfd); goto cleanup; }
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; } err = 0;
cleanup: bpf_link__destroy(link); return err;}
int main(int argc, char **argv){ extern char __executable_start; char filename[256], buf[256]; __u64 uprobe_file_offset; struct bpf_program *prog; struct bpf_object *obj; int i = 0, err = -1;
if (load_kallsyms()) { printf("failed to process /proc/kallsyms\n"); return err; }
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); obj = bpf_object__open_file(filename, NULL); if (libbpf_get_error(obj)) { fprintf(stderr, "ERROR: opening BPF object file failed\n"); return err; }
/* load BPF program */ if (bpf_object__load(obj)) { fprintf(stderr, "ERROR: loading BPF object file failed\n"); goto cleanup; }
bpf_object__for_each_program(prog, obj) { progs[i] = prog; links[i] = bpf_program__attach(progs[i]); if (libbpf_get_error(links[i])) { fprintf(stderr, "ERROR: bpf_program__attach failed\n"); links[i] = NULL; goto cleanup; } i++; }
/* test two functions in the corresponding *_kern.c file */ CHECK_AND_RET(test_debug_fs_kprobe(0, "blk_mq_start_request", BPF_FD_TYPE_KPROBE)); CHECK_AND_RET(test_debug_fs_kprobe(1, "__blk_account_io_done", 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 = (unsigned long)main - (unsigned long)&__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)); err = 0;
cleanup: for (i--; i >= 0; i--) bpf_link__destroy(links[i]);
bpf_object__close(obj); return err;}