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a195cefff4
GCC 9 fails to calculate the size of local constant strings and produces a
false positive:
samples/bpf/task_fd_query_user.c: In function ‘test_debug_fs_uprobe’:
samples/bpf/task_fd_query_user.c:242:67: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size 215 [-Wformat-truncation=]
242 | snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
| ^~
243 | event_type, event_alias);
| ~~~~~~~~~~~
samples/bpf/task_fd_query_user.c:242:2: note: ‘snprintf’ output between 45 and 300 bytes into a destination of size 256
242 | snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
243 | event_type, event_alias);
| ~~~~~~~~~~~~~~~~~~~~~~~~
Workaround this by lowering the buffer size to a reasonable value.
Related GCC Bugzilla: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83431
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
383 lines
10 KiB
C
383 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <unistd.h>
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#include <stdbool.h>
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#include <string.h>
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#include <stdint.h>
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#include <fcntl.h>
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#include <linux/bpf.h>
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#include <sys/ioctl.h>
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#include <sys/resource.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include "libbpf.h"
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#include "bpf_load.h"
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#include "bpf_util.h"
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#include "perf-sys.h"
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#include "trace_helpers.h"
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#define CHECK_PERROR_RET(condition) ({ \
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int __ret = !!(condition); \
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if (__ret) { \
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printf("FAIL: %s:\n", __func__); \
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perror(" "); \
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return -1; \
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} \
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})
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#define CHECK_AND_RET(condition) ({ \
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int __ret = !!(condition); \
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if (__ret) \
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return -1; \
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})
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static __u64 ptr_to_u64(void *ptr)
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{
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return (__u64) (unsigned long) ptr;
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}
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#define PMU_TYPE_FILE "/sys/bus/event_source/devices/%s/type"
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static int bpf_find_probe_type(const char *event_type)
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{
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char buf[256];
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int fd, ret;
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ret = snprintf(buf, sizeof(buf), PMU_TYPE_FILE, event_type);
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CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
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fd = open(buf, O_RDONLY);
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CHECK_PERROR_RET(fd < 0);
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ret = read(fd, buf, sizeof(buf));
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close(fd);
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CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
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errno = 0;
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ret = (int)strtol(buf, NULL, 10);
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CHECK_PERROR_RET(errno);
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return ret;
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}
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#define PMU_RETPROBE_FILE "/sys/bus/event_source/devices/%s/format/retprobe"
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static int bpf_get_retprobe_bit(const char *event_type)
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{
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char buf[256];
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int fd, ret;
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ret = snprintf(buf, sizeof(buf), PMU_RETPROBE_FILE, event_type);
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CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
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fd = open(buf, O_RDONLY);
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CHECK_PERROR_RET(fd < 0);
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ret = read(fd, buf, sizeof(buf));
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close(fd);
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CHECK_PERROR_RET(ret < 0 || ret >= sizeof(buf));
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CHECK_PERROR_RET(strlen(buf) < strlen("config:"));
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errno = 0;
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ret = (int)strtol(buf + strlen("config:"), NULL, 10);
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CHECK_PERROR_RET(errno);
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return ret;
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}
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static int test_debug_fs_kprobe(int prog_fd_idx, const char *fn_name,
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__u32 expected_fd_type)
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{
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__u64 probe_offset, probe_addr;
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__u32 len, prog_id, fd_type;
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char buf[256];
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int err;
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len = sizeof(buf);
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err = bpf_task_fd_query(getpid(), event_fd[prog_fd_idx], 0, buf, &len,
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&prog_id, &fd_type, &probe_offset,
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&probe_addr);
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if (err < 0) {
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printf("FAIL: %s, for event_fd idx %d, fn_name %s\n",
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__func__, prog_fd_idx, fn_name);
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perror(" :");
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return -1;
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}
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if (strcmp(buf, fn_name) != 0 ||
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fd_type != expected_fd_type ||
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probe_offset != 0x0 || probe_addr != 0x0) {
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printf("FAIL: bpf_trace_event_query(event_fd[%d]):\n",
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prog_fd_idx);
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printf("buf: %s, fd_type: %u, probe_offset: 0x%llx,"
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" probe_addr: 0x%llx\n",
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buf, fd_type, probe_offset, probe_addr);
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return -1;
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}
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return 0;
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}
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static int test_nondebug_fs_kuprobe_common(const char *event_type,
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const char *name, __u64 offset, __u64 addr, bool is_return,
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char *buf, __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
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__u64 *probe_offset, __u64 *probe_addr)
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{
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int is_return_bit = bpf_get_retprobe_bit(event_type);
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int type = bpf_find_probe_type(event_type);
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struct perf_event_attr attr = {};
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int fd;
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if (type < 0 || is_return_bit < 0) {
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printf("FAIL: %s incorrect type (%d) or is_return_bit (%d)\n",
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__func__, type, is_return_bit);
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return -1;
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}
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attr.sample_period = 1;
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attr.wakeup_events = 1;
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if (is_return)
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attr.config |= 1 << is_return_bit;
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if (name) {
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attr.config1 = ptr_to_u64((void *)name);
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attr.config2 = offset;
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} else {
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attr.config1 = 0;
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attr.config2 = addr;
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}
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attr.size = sizeof(attr);
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attr.type = type;
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fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
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CHECK_PERROR_RET(fd < 0);
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CHECK_PERROR_RET(ioctl(fd, PERF_EVENT_IOC_ENABLE, 0) < 0);
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CHECK_PERROR_RET(ioctl(fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) < 0);
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CHECK_PERROR_RET(bpf_task_fd_query(getpid(), fd, 0, buf, buf_len,
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prog_id, fd_type, probe_offset, probe_addr) < 0);
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return 0;
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}
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static int test_nondebug_fs_probe(const char *event_type, const char *name,
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__u64 offset, __u64 addr, bool is_return,
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__u32 expected_fd_type,
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__u32 expected_ret_fd_type,
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char *buf, __u32 buf_len)
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{
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__u64 probe_offset, probe_addr;
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__u32 prog_id, fd_type;
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int err;
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err = test_nondebug_fs_kuprobe_common(event_type, name,
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offset, addr, is_return,
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buf, &buf_len, &prog_id,
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&fd_type, &probe_offset,
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&probe_addr);
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if (err < 0) {
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printf("FAIL: %s, "
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"for name %s, offset 0x%llx, addr 0x%llx, is_return %d\n",
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__func__, name ? name : "", offset, addr, is_return);
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perror(" :");
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return -1;
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}
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if ((is_return && fd_type != expected_ret_fd_type) ||
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(!is_return && fd_type != expected_fd_type)) {
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printf("FAIL: %s, incorrect fd_type %u\n",
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__func__, fd_type);
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return -1;
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}
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if (name) {
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if (strcmp(name, buf) != 0) {
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printf("FAIL: %s, incorrect buf %s\n", __func__, buf);
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return -1;
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}
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if (probe_offset != offset) {
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printf("FAIL: %s, incorrect probe_offset 0x%llx\n",
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__func__, probe_offset);
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return -1;
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}
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} else {
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if (buf_len != 0) {
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printf("FAIL: %s, incorrect buf %p\n",
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__func__, buf);
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return -1;
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}
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if (probe_addr != addr) {
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printf("FAIL: %s, incorrect probe_addr 0x%llx\n",
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__func__, probe_addr);
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return -1;
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}
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}
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return 0;
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}
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static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
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{
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const char *event_type = "uprobe";
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struct perf_event_attr attr = {};
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char buf[256], event_alias[sizeof("test_1234567890")];
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__u64 probe_offset, probe_addr;
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__u32 len, prog_id, fd_type;
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int err, res, kfd, efd;
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ssize_t bytes;
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snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
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event_type);
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kfd = open(buf, O_WRONLY | O_APPEND, 0);
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CHECK_PERROR_RET(kfd < 0);
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res = snprintf(event_alias, sizeof(event_alias), "test_%d", getpid());
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CHECK_PERROR_RET(res < 0 || res >= sizeof(event_alias));
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res = snprintf(buf, sizeof(buf), "%c:%ss/%s %s:0x%lx",
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is_return ? 'r' : 'p', event_type, event_alias,
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binary_path, offset);
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CHECK_PERROR_RET(res < 0 || res >= sizeof(buf));
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CHECK_PERROR_RET(write(kfd, buf, strlen(buf)) < 0);
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close(kfd);
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kfd = -1;
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snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
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event_type, event_alias);
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efd = open(buf, O_RDONLY, 0);
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CHECK_PERROR_RET(efd < 0);
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bytes = read(efd, buf, sizeof(buf));
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CHECK_PERROR_RET(bytes <= 0 || bytes >= sizeof(buf));
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close(efd);
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buf[bytes] = '\0';
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attr.config = strtol(buf, NULL, 0);
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attr.type = PERF_TYPE_TRACEPOINT;
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attr.sample_period = 1;
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attr.wakeup_events = 1;
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kfd = sys_perf_event_open(&attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
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CHECK_PERROR_RET(kfd < 0);
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CHECK_PERROR_RET(ioctl(kfd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) < 0);
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CHECK_PERROR_RET(ioctl(kfd, PERF_EVENT_IOC_ENABLE, 0) < 0);
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len = sizeof(buf);
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err = bpf_task_fd_query(getpid(), kfd, 0, buf, &len,
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&prog_id, &fd_type, &probe_offset,
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&probe_addr);
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if (err < 0) {
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printf("FAIL: %s, binary_path %s\n", __func__, binary_path);
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perror(" :");
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return -1;
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}
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if ((is_return && fd_type != BPF_FD_TYPE_URETPROBE) ||
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(!is_return && fd_type != BPF_FD_TYPE_UPROBE)) {
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printf("FAIL: %s, incorrect fd_type %u\n", __func__,
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fd_type);
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return -1;
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}
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if (strcmp(binary_path, buf) != 0) {
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printf("FAIL: %s, incorrect buf %s\n", __func__, buf);
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return -1;
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}
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if (probe_offset != offset) {
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printf("FAIL: %s, incorrect probe_offset 0x%llx\n", __func__,
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probe_offset);
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return -1;
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}
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close(kfd);
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return 0;
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}
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int main(int argc, char **argv)
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{
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struct rlimit r = {1024*1024, RLIM_INFINITY};
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extern char __executable_start;
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char filename[256], buf[256];
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__u64 uprobe_file_offset;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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if (setrlimit(RLIMIT_MEMLOCK, &r)) {
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perror("setrlimit(RLIMIT_MEMLOCK)");
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return 1;
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}
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if (load_kallsyms()) {
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printf("failed to process /proc/kallsyms\n");
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return 1;
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}
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if (load_bpf_file(filename)) {
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printf("%s", bpf_log_buf);
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return 1;
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}
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/* test two functions in the corresponding *_kern.c file */
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CHECK_AND_RET(test_debug_fs_kprobe(0, "blk_mq_start_request",
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BPF_FD_TYPE_KPROBE));
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CHECK_AND_RET(test_debug_fs_kprobe(1, "blk_account_io_completion",
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BPF_FD_TYPE_KRETPROBE));
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/* test nondebug fs kprobe */
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x0, 0x0,
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false, BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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buf, sizeof(buf)));
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#ifdef __x86_64__
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/* set a kprobe on "bpf_check + 0x5", which is x64 specific */
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x5, 0x0,
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false, BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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buf, sizeof(buf)));
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#endif
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", "bpf_check", 0x0, 0x0,
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true, BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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buf, sizeof(buf)));
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
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ksym_get_addr("bpf_check"), false,
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BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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buf, sizeof(buf)));
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
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ksym_get_addr("bpf_check"), false,
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BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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NULL, 0));
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
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ksym_get_addr("bpf_check"), true,
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BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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buf, sizeof(buf)));
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CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
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ksym_get_addr("bpf_check"), true,
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BPF_FD_TYPE_KPROBE,
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BPF_FD_TYPE_KRETPROBE,
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0, 0));
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/* test nondebug fs uprobe */
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/* the calculation of uprobe file offset is based on gcc 7.3.1 on x64
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* and the default linker script, which defines __executable_start as
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* the start of the .text section. The calculation could be different
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* on different systems with different compilers. The right way is
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* to parse the ELF file. We took a shortcut here.
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*/
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uprobe_file_offset = (__u64)main - (__u64)&__executable_start;
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CHECK_AND_RET(test_nondebug_fs_probe("uprobe", (char *)argv[0],
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uprobe_file_offset, 0x0, false,
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BPF_FD_TYPE_UPROBE,
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BPF_FD_TYPE_URETPROBE,
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buf, sizeof(buf)));
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CHECK_AND_RET(test_nondebug_fs_probe("uprobe", (char *)argv[0],
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uprobe_file_offset, 0x0, true,
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BPF_FD_TYPE_UPROBE,
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BPF_FD_TYPE_URETPROBE,
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buf, sizeof(buf)));
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/* test debug fs uprobe */
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CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
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false));
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CHECK_AND_RET(test_debug_fs_uprobe((char *)argv[0], uprobe_file_offset,
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true));
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return 0;
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}
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