1 /*
2 * Copyright (C) 2020 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "ProbeEvents.h"
18
19 #include <inttypes.h>
20
21 #include <memory>
22 #include <regex>
23 #include <string>
24
25 #include <android-base/file.h>
26 #include <android-base/logging.h>
27 #include <android-base/parseint.h>
28 #include <android-base/stringprintf.h>
29 #include <android-base/strings.h>
30 #include <android-base/unique_fd.h>
31
32 #include "environment.h"
33 #include "event_type.h"
34 #include "utils.h"
35
36 namespace simpleperf {
37
38 using android::base::ParseInt;
39 using android::base::ParseUint;
40 using android::base::Split;
41 using android::base::StringPrintf;
42 using android::base::unique_fd;
43 using android::base::WriteStringToFd;
44
45 static const std::string kKprobeEventPrefix = "kprobes:";
46
ParseKprobeEventName(const std::string & kprobe_cmd,ProbeEvent * event)47 bool ProbeEvents::ParseKprobeEventName(const std::string& kprobe_cmd, ProbeEvent* event) {
48 // kprobe_cmd is in formats described in <kernel>/Documentation/trace/kprobetrace.rst:
49 // p[:[GRP/]EVENT] [MOD:]SYM[+offs]|MEMADDR [FETCHARGS]
50 // r[MAXACTIVE][:[GRP/]EVENT] [MOD:]SYM[+offs] [FETCHARGS]
51 std::vector<std::string> args = Split(kprobe_cmd, " ");
52 if (args.size() < 2) {
53 return false;
54 }
55
56 // Parse given name.
57 event->group_name = "kprobes";
58 std::regex name_reg(R"(:([a-zA-Z_][\w_]*/)?([a-zA-Z_][\w_]*))");
59 std::smatch matches;
60 if (std::regex_search(args[0], matches, name_reg)) {
61 if (matches[1].length() > 0) {
62 event->group_name = matches[1].str();
63 event->group_name.pop_back();
64 }
65 event->event_name = matches[2].str();
66 return true;
67 }
68
69 // Generate name from MEMADDR.
70 char probe_type = args[0][0];
71 uint64_t kaddr;
72 if (ParseUint(args[1], &kaddr)) {
73 event->event_name = StringPrintf("%c_0x%" PRIx64, probe_type, kaddr);
74 return true;
75 }
76
77 // Generate name from [MOD:]SYM[+offs].
78 std::string symbol;
79 int64_t offset;
80 size_t split_pos = args[1].find_first_of("+-");
81 if (split_pos == std::string::npos) {
82 symbol = args[1];
83 offset = 0;
84 } else {
85 symbol = args[1].substr(0, split_pos);
86 if (!ParseInt(args[1].substr(split_pos), &offset) || offset < 0) {
87 return false;
88 }
89 }
90 std::string s = StringPrintf("%c_%s_%" PRId64, probe_type, symbol.c_str(), offset);
91 event->event_name = std::regex_replace(s, std::regex(R"(\.|:)"), "_");
92 return true;
93 }
94
IsKprobeSupported()95 bool ProbeEvents::IsKprobeSupported() {
96 if (!kprobe_control_path_.has_value()) {
97 kprobe_control_path_ = "";
98 if (const char* tracefs_dir = GetTraceFsDir(); tracefs_dir != nullptr) {
99 std::string path = std::string(tracefs_dir) + "/kprobe_events";
100 if (IsRegularFile(path)) {
101 kprobe_control_path_ = std::move(path);
102 }
103 }
104 }
105 return !kprobe_control_path_.value().empty();
106 }
107
AddKprobe(const std::string & kprobe_cmd)108 bool ProbeEvents::AddKprobe(const std::string& kprobe_cmd) {
109 ProbeEvent event;
110 if (!ParseKprobeEventName(kprobe_cmd, &event)) {
111 LOG(ERROR) << "invalid kprobe cmd: " << kprobe_cmd;
112 return false;
113 }
114 if (!WriteKprobeCmd(kprobe_cmd)) {
115 return false;
116 }
117 kprobe_events_.emplace_back(std::move(event));
118 return true;
119 }
120
IsProbeEvent(const std::string & event_name)121 bool ProbeEvents::IsProbeEvent(const std::string& event_name) {
122 return android::base::StartsWith(event_name, kKprobeEventPrefix);
123 }
124
CreateProbeEventIfNotExist(const std::string & event_name)125 bool ProbeEvents::CreateProbeEventIfNotExist(const std::string& event_name) {
126 if (EventTypeManager::Instance().FindType(event_name) != nullptr) {
127 return true;
128 }
129 std::string function_name = event_name.substr(kKprobeEventPrefix.size());
130 return AddKprobe(StringPrintf("p:%s %s", function_name.c_str(), function_name.c_str()));
131 }
132
Clear()133 void ProbeEvents::Clear() {
134 for (const auto& kprobe_event : kprobe_events_) {
135 if (!WriteKprobeCmd("-:" + kprobe_event.group_name + "/" + kprobe_event.event_name)) {
136 LOG(WARNING) << "failed to delete kprobe event " << kprobe_event.group_name << ":"
137 << kprobe_event.event_name;
138 }
139 EventTypeManager::Instance().RemoveProbeType(kprobe_event.group_name + ":" +
140 kprobe_event.event_name);
141 }
142 kprobe_events_.clear();
143 }
144
WriteKprobeCmd(const std::string & kprobe_cmd)145 bool ProbeEvents::WriteKprobeCmd(const std::string& kprobe_cmd) {
146 if (!IsKprobeSupported()) {
147 LOG(ERROR) << "kprobe events isn't supported by the kernel.";
148 return false;
149 }
150 const std::string& path = kprobe_control_path_.value();
151 unique_fd fd(open(path.c_str(), O_APPEND | O_WRONLY | O_CLOEXEC));
152 if (!fd.ok()) {
153 PLOG(ERROR) << "failed to open " << path;
154 return false;
155 }
156 if (!WriteStringToFd(kprobe_cmd, fd)) {
157 PLOG(ERROR) << "failed to write '" << kprobe_cmd << "' to " << path;
158 return false;
159 }
160 return true;
161 }
162
163 } // namespace simpleperf
164