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-rw-r--r--tools/bpf/bpftool/tracelog.c166
1 files changed, 166 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/tracelog.c b/tools/bpf/bpftool/tracelog.c
new file mode 100644
index 000000000..bf1f02212
--- /dev/null
+++ b/tools/bpf/bpftool/tracelog.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (c) 2015-2017 Daniel Borkmann */
+/* Copyright (c) 2018 Netronome Systems, Inc. */
+
+#include <errno.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/magic.h>
+#include <fcntl.h>
+#include <sys/vfs.h>
+
+#include "main.h"
+
+#ifndef TRACEFS_MAGIC
+# define TRACEFS_MAGIC 0x74726163
+#endif
+
+#define _textify(x) #x
+#define textify(x) _textify(x)
+
+FILE *trace_pipe_fd;
+char *buff;
+
+static int validate_tracefs_mnt(const char *mnt, unsigned long magic)
+{
+ struct statfs st_fs;
+
+ if (statfs(mnt, &st_fs) < 0)
+ return -ENOENT;
+ if ((unsigned long)st_fs.f_type != magic)
+ return -ENOENT;
+
+ return 0;
+}
+
+static bool
+find_tracefs_mnt_single(unsigned long magic, char *mnt, const char *mntpt)
+{
+ size_t src_len;
+
+ if (validate_tracefs_mnt(mntpt, magic))
+ return false;
+
+ src_len = strlen(mntpt);
+ if (src_len + 1 >= PATH_MAX) {
+ p_err("tracefs mount point name too long");
+ return false;
+ }
+
+ strcpy(mnt, mntpt);
+ return true;
+}
+
+static bool get_tracefs_pipe(char *mnt)
+{
+ static const char * const known_mnts[] = {
+ "/sys/kernel/debug/tracing",
+ "/sys/kernel/tracing",
+ "/tracing",
+ "/trace",
+ };
+ const char *pipe_name = "/trace_pipe";
+ const char *fstype = "tracefs";
+ char type[100], format[32];
+ const char * const *ptr;
+ bool found = false;
+ FILE *fp;
+
+ for (ptr = known_mnts; ptr < known_mnts + ARRAY_SIZE(known_mnts); ptr++)
+ if (find_tracefs_mnt_single(TRACEFS_MAGIC, mnt, *ptr))
+ goto exit_found;
+
+ fp = fopen("/proc/mounts", "r");
+ if (!fp)
+ return false;
+
+ /* Allow room for NULL terminating byte and pipe file name */
+ snprintf(format, sizeof(format), "%%*s %%%zds %%99s %%*s %%*d %%*d\\n",
+ PATH_MAX - strlen(pipe_name) - 1);
+ while (fscanf(fp, format, mnt, type) == 2)
+ if (strcmp(type, fstype) == 0) {
+ found = true;
+ break;
+ }
+ fclose(fp);
+
+ /* The string from fscanf() might be truncated, check mnt is valid */
+ if (found && validate_tracefs_mnt(mnt, TRACEFS_MAGIC))
+ goto exit_found;
+
+ if (block_mount)
+ return false;
+
+ p_info("could not find tracefs, attempting to mount it now");
+ /* Most of the time, tracefs is automatically mounted by debugfs at
+ * /sys/kernel/debug/tracing when we try to access it. If we could not
+ * find it, it is likely that debugfs is not mounted. Let's give one
+ * attempt at mounting just tracefs at /sys/kernel/tracing.
+ */
+ strcpy(mnt, known_mnts[1]);
+ if (mount_tracefs(mnt))
+ return false;
+
+exit_found:
+ strcat(mnt, pipe_name);
+ return true;
+}
+
+static void exit_tracelog(int signum)
+{
+ fclose(trace_pipe_fd);
+ free(buff);
+
+ if (json_output) {
+ jsonw_end_array(json_wtr);
+ jsonw_destroy(&json_wtr);
+ }
+
+ exit(0);
+}
+
+int do_tracelog(int argc, char **argv)
+{
+ const struct sigaction act = {
+ .sa_handler = exit_tracelog
+ };
+ char trace_pipe[PATH_MAX];
+ size_t buff_len = 0;
+
+ if (json_output)
+ jsonw_start_array(json_wtr);
+
+ if (!get_tracefs_pipe(trace_pipe))
+ return -1;
+
+ trace_pipe_fd = fopen(trace_pipe, "r");
+ if (!trace_pipe_fd) {
+ p_err("could not open trace pipe: %s", strerror(errno));
+ return -1;
+ }
+
+ sigaction(SIGHUP, &act, NULL);
+ sigaction(SIGINT, &act, NULL);
+ sigaction(SIGTERM, &act, NULL);
+ while (1) {
+ ssize_t ret;
+
+ ret = getline(&buff, &buff_len, trace_pipe_fd);
+ if (ret <= 0) {
+ p_err("failed to read content from trace pipe: %s",
+ strerror(errno));
+ break;
+ }
+ if (json_output)
+ jsonw_string(json_wtr, buff);
+ else
+ printf("%s", buff);
+ }
+
+ fclose(trace_pipe_fd);
+ free(buff);
+ return -1;
+}