gs_watchdogd: Add platform watchdog daemon

Bug: 238701471
Change-Id: Ib49ad5f31fdcda7d2d115b2de1bc429e4788100c

device.mk

@@ -20,3 +20,10 @@ PRODUCT_SOONG_NAMESPACES += \
 # Disable OMX
 PRODUCT_PROPERTY_OVERRIDES += \
 	vendor.media.omx=0
+
+# Platform watchdogd
+PRODUCT_PACKAGES += gs_watchdogd
+PRODUCT_SOONG_NAMESPACES += \
+	device/google/gs-common/gs_watchdogd
+SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS += \
+	hardware/google/pixel-sepolicy/gs_watchdogd

gs_watchdogd/Android.bp

@@ -0,0 +1,20 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_binary {
+    name: "gs_watchdogd",
+    recovery_available: true,
+    system_ext_specific: true,
+    init_rc: ["init.gs_watchdogd.rc"],
+    srcs: ["gs_watchdogd.cpp"],
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+    ],
+    shared_libs: ["libbase"],
+    sanitize: {
+        misc_undefined: ["signed-integer-overflow"],
+    },
+}

gs_watchdogd/gs_watchdogd.cpp

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2022 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 <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <glob.h>
+#include <linux/watchdog.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define DEV_GLOB "/sys/devices/platform/*.watchdog_cl0/watchdog/watchdog*"
+
+using android::base::Basename;
+using android::base::StringPrintf;
+
+int main(int argc, char** argv) {
+    android::base::InitLogging(argv, &android::base::KernelLogger);
+
+    int interval = 10;
+    if (argc >= 2) interval = atoi(argv[1]);
+
+    int margin = 10;
+    if (argc >= 3) margin = atoi(argv[2]);
+
+    LOG(INFO) << "gs_watchdogd started (interval " << interval << ", margin " << margin << ")!";
+
+    glob_t globbuf;
+    int ret = glob(DEV_GLOB, GLOB_MARK, nullptr, &globbuf);
+    if (ret) {
+        PLOG(ERROR) << "Failed to lookup glob " << DEV_GLOB << ": " << ret;
+        return 1;
+    }
+
+    if (globbuf.gl_pathc > 1) {
+        PLOG(WARNING) << "Multiple watchdog dev path found by " << DEV_GLOB;
+    }
+
+    std::string dev_path = StringPrintf("/dev/%s", Basename(globbuf.gl_pathv[0]).c_str());
+    globfree(&globbuf);
+
+    int fd = open(dev_path.c_str(), O_RDWR | O_CLOEXEC);
+    if (fd == -1) {
+        PLOG(ERROR) << "Failed to open " << dev_path;
+        return 1;
+    }
+
+    int timeout = interval + margin;
+    ret = ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
+    if (ret) {
+        PLOG(ERROR) << "Failed to set timeout to " << timeout;
+        ret = ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
+        if (ret) {
+            PLOG(ERROR) << "Failed to get timeout";
+        } else {
+            if (timeout > margin) {
+                interval = timeout - margin;
+            } else {
+                interval = 1;
+            }
+            LOG(WARNING) << "Adjusted interval to timeout returned by driver: "
+                         << "timeout " << timeout << ", interval " << interval << ", margin "
+                         << margin;
+        }
+    }
+
+    while (true) {
+        write(fd, "", 1);
+        sleep(interval);
+    }
+}

gs_watchdogd/init.gs_watchdogd.rc

@@ -0,0 +1,8 @@
+# Set watchdog timer to 30 seconds and pet it every 10 seconds to get a 20 second margin
+service gs_watchdogd /system_ext/bin/gs_watchdogd 10 20
+    class core
+    oneshot
+    seclabel u:r:gs_watchdogd:s0
+
+on init && property:vendor.all.devices.ready=1
+    start gs_watchdogd