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;
+}