1// SPDX-License-Identifier: GPL-2.0
  2#ifndef _GNU_SOURCE
  3# define _GNU_SOURCE
  4#endif
  5
  6#include <stdio.h>
  7#include <stdlib.h>
  8#include <string.h>
  9#include <linux/string.h>
 10#include <errno.h>
 11#include <unistd.h>
 12#include "fs.h"
 13
 14#include "tracing_path.h"
 15
 16
 17char tracing_mnt[PATH_MAX]         = "/sys/kernel/debug";
 18char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
 19char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
 20
 21
 22static void __tracing_path_set(const char *tracing, const char *mountpoint)
 23{
 24	snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
 25	snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
 26		 mountpoint, tracing);
 27	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
 28		 mountpoint, tracing, "events");
 29}
 30
 31static const char *tracing_path_tracefs_mount(void)
 32{
 33	const char *mnt;
 34
 35	mnt = tracefs__mount();
 36	if (!mnt)
 37		return NULL;
 38
 39	__tracing_path_set("", mnt);
 40
 41	return mnt;
 42}
 43
 44static const char *tracing_path_debugfs_mount(void)
 45{
 46	const char *mnt;
 47
 48	mnt = debugfs__mount();
 49	if (!mnt)
 50		return NULL;
 51
 52	__tracing_path_set("tracing/", mnt);
 53
 54	return mnt;
 55}
 56
 57const char *tracing_path_mount(void)
 58{
 59	const char *mnt;
 60
 61	mnt = tracing_path_tracefs_mount();
 62	if (mnt)
 63		return mnt;
 64
 65	mnt = tracing_path_debugfs_mount();
 66
 67	return mnt;
 68}
 69
 70void tracing_path_set(const char *mntpt)
 71{
 72	__tracing_path_set("tracing/", mntpt);
 73}
 74
 75char *get_tracing_file(const char *name)
 76{
 77	char *file;
 78
 79	if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
 80		return NULL;
 81
 82	return file;
 83}
 84
 85void put_tracing_file(char *file)
 86{
 87	free(file);
 88}
 89
 90int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
 91				   const char *sys, const char *name)
 92{
 93	char sbuf[128];
 94	char filename[PATH_MAX];
 95
 96	snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");
 97
 98	switch (err) {
 99	case ENOENT:
100		/*
101		 * We will get here if we can't find the tracepoint, but one of
102		 * debugfs or tracefs is configured, which means you probably
103		 * want some tracepoint which wasn't compiled in your kernel.
104		 * - jirka
105		 */
106		if (debugfs__configured() || tracefs__configured()) {
107			/* sdt markers */
108			if (!strncmp(filename, "sdt_", 4)) {
109				snprintf(buf, size,
110					"Error:\tFile %s/%s not found.\n"
111					"Hint:\tSDT event cannot be directly recorded on.\n"
112					"\tPlease first use 'perf probe %s:%s' before recording it.\n",
113					tracing_events_path, filename, sys, name);
114			} else {
115				snprintf(buf, size,
116					 "Error:\tFile %s/%s not found.\n"
117					 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
118					 tracing_events_path, filename);
119			}
120			break;
121		}
122		snprintf(buf, size, "%s",
123			 "Error:\tUnable to find debugfs/tracefs\n"
124			 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
125			 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
126			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
127		break;
128	case EACCES: {
129		snprintf(buf, size,
130			 "Error:\tNo permissions to read %s/%s\n"
131			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
132			 tracing_events_path, filename, tracing_mnt);
133	}
134		break;
135	default:
136		snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
137		break;
138	}
139
140	return 0;
141}