1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <sys/capability.h>
#include <sys/reboot.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <string>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <backtrace/Backtrace.h>
#include <cutils/android_reboot.h>
#include "capabilities.h"
namespace android {
namespace init {
static std::string init_fatal_reboot_target = "bootloader";
void SetFatalRebootTarget() {
std::string cmdline;
android::base::ReadFileToString("/proc/cmdline", &cmdline);
cmdline = android::base::Trim(cmdline);
const char kRebootTargetString[] = "androidboot.init_fatal_reboot_target=";
auto start_pos = cmdline.find(kRebootTargetString);
if (start_pos == std::string::npos) {
return; // We already default to bootloader if no setting is provided.
}
start_pos += sizeof(kRebootTargetString) - 1;
auto end_pos = cmdline.find(' ', start_pos);
// if end_pos isn't found, then we've run off the end, but this is okay as this is the last
// entry, and -1 is a valid size for string::substr();
auto size = end_pos == std::string::npos ? -1 : end_pos - start_pos;
init_fatal_reboot_target = cmdline.substr(start_pos, size);
}
bool IsRebootCapable() {
if (!CAP_IS_SUPPORTED(CAP_SYS_BOOT)) {
PLOG(WARNING) << "CAP_SYS_BOOT is not supported";
return true;
}
ScopedCaps caps(cap_get_proc());
if (!caps) {
PLOG(WARNING) << "cap_get_proc() failed";
return true;
}
cap_flag_value_t value = CAP_SET;
if (cap_get_flag(caps.get(), CAP_SYS_BOOT, CAP_EFFECTIVE, &value) != 0) {
PLOG(WARNING) << "cap_get_flag(CAP_SYS_BOOT, EFFECTIVE) failed";
return true;
}
return value == CAP_SET;
}
void __attribute__((noreturn)) RebootSystem(unsigned int cmd, const std::string& rebootTarget) {
LOG(INFO) << "Reboot ending, jumping to kernel";
if (!IsRebootCapable()) {
// On systems where init does not have the capability of rebooting the
// device, just exit cleanly.
exit(0);
}
switch (cmd) {
case ANDROID_RB_POWEROFF:
reboot(RB_POWER_OFF);
break;
case ANDROID_RB_RESTART2:
syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, rebootTarget.c_str());
break;
case ANDROID_RB_THERMOFF:
if (android::base::GetBoolProperty("ro.thermal_warmreset", false)) {
LOG(INFO) << "Try to trigger a warm reset for thermal shutdown";
static constexpr const char kThermalShutdownTarget[] = "shutdown,thermal";
syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, kThermalShutdownTarget);
} else {
reboot(RB_POWER_OFF);
}
break;
}
// In normal case, reboot should not return.
PLOG(ERROR) << "reboot call returned";
abort();
}
void __attribute__((noreturn)) InitFatalReboot() {
auto pid = fork();
if (pid == -1) {
// Couldn't fork, don't even try to backtrace, just reboot.
RebootSystem(ANDROID_RB_RESTART2, init_fatal_reboot_target);
} else if (pid == 0) {
// Fork a child for safety, since we always want to shut down if something goes wrong, but
// its worth trying to get the backtrace, even in the signal handler, since typically it
// does work despite not being async-signal-safe.
sleep(5);
RebootSystem(ANDROID_RB_RESTART2, init_fatal_reboot_target);
}
// In the parent, let's try to get a backtrace then shutdown.
std::unique_ptr<Backtrace> backtrace(
Backtrace::Create(BACKTRACE_CURRENT_PROCESS, BACKTRACE_CURRENT_THREAD));
if (!backtrace->Unwind(0)) {
LOG(ERROR) << __FUNCTION__ << ": Failed to unwind callstack.";
}
for (size_t i = 0; i < backtrace->NumFrames(); i++) {
LOG(ERROR) << backtrace->FormatFrameData(i);
}
RebootSystem(ANDROID_RB_RESTART2, init_fatal_reboot_target);
}
void InstallRebootSignalHandlers() {
// Instead of panic'ing the kernel as is the default behavior when init crashes,
// we prefer to reboot to bootloader on development builds, as this will prevent
// boot looping bad configurations and allow both developers and test farms to easily
// recover.
struct sigaction action;
memset(&action, 0, sizeof(action));
sigfillset(&action.sa_mask);
action.sa_handler = [](int signal) {
// These signal handlers are also caught for processes forked from init, however we do not
// want them to trigger reboot, so we directly call _exit() for children processes here.
if (getpid() != 1) {
_exit(signal);
}
// Calling DoReboot() or LOG(FATAL) is not a good option as this is a signal handler.
// RebootSystem uses syscall() which isn't actually async-signal-safe, but our only option
// and probably good enough given this is already an error case and only enabled for
// development builds.
InitFatalReboot();
};
action.sa_flags = SA_RESTART;
sigaction(SIGABRT, &action, nullptr);
sigaction(SIGBUS, &action, nullptr);
sigaction(SIGFPE, &action, nullptr);
sigaction(SIGILL, &action, nullptr);
sigaction(SIGSEGV, &action, nullptr);
#if defined(SIGSTKFLT)
sigaction(SIGSTKFLT, &action, nullptr);
#endif
sigaction(SIGSYS, &action, nullptr);
sigaction(SIGTRAP, &action, nullptr);
}
} // namespace init
} // namespace android
|
