Implement crashdump
crashdump is a small binary which copies the ramdump from /proc/vmcore to /dev/hvc3 which will be backed by a file outside of the VM. crashdump is included in a init ramdisk image, and will be executed as the init process when a kernel panic occurs. Bug: 237381237 Test: N/A (follow-up CL needed) Change-Id: Iecac0b437a2f512348ee28abe8b2bf6b23640029
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@ -104,6 +104,7 @@ android_system_image {
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"microdroid_plat_sepolicy.cil",
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"microdroid_plat_mapping_file",
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"microdroid_crashdump_initrd",
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],
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},
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lib64: {
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@ -8,3 +8,21 @@ cc_binary {
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srcs: ["kexec.c"],
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installable: false,
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}
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cc_binary {
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name: "microdroid_crashdump",
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stem: "crashdump",
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srcs: ["crashdump.c"],
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static_executable: true,
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installable: false,
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}
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android_filesystem {
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name: "microdroid_crashdump_initrd",
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deps: ["microdroid_crashdump"],
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dirs: [
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"dev",
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"proc",
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],
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type: "cpio",
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}
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@ -0,0 +1,120 @@
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/*
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* Copyright (C) 2022 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// This program runs as init in the crash kernel.
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/reboot.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <termios.h>
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#include <unistd.h>
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#define DUMP_SOURCE "/proc/vmcore"
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#define DUMP_TARGET "/dev/hvc3" // See virtualizationserice/crosvm.rs
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#define BUF_SIZE 4096
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#define FAIL(format, ...) \
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{ \
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fprintf(stderr, format ":%s\n", ##__VA_ARGS__, strerror(errno)); \
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goto fail; \
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}
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// Why declare? __reboot() is the Bionic's system call stub for the reboot syscall. It is
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// automatically generated (and is part of API), but Bionic doesn't export this in its headers.
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extern int __reboot(int, int, int, void*);
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int main() {
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printf("Crashdump started\n");
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if (mount("proc", "/proc", "proc", 0, NULL) == -1) {
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FAIL("Failed to mount /proc");
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}
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if (mount("devtmpfs", "/dev", "devtmpfs", 0, NULL) == -1) {
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FAIL("Failed to mount /dev");
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}
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int vmcore = open(DUMP_SOURCE, O_RDONLY);
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if (vmcore == -1) {
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FAIL("Failed to open %s", DUMP_SOURCE);
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}
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int dest = open(DUMP_TARGET, O_WRONLY);
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if (dest == -1) {
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FAIL("Failed to open %s", DUMP_TARGET);
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}
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// We need to turn the line discipline off, otherwise the virtio-console will automatically
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// append more data than what we have written because some will be recognized as a control
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// sequence.
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struct termios term;
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if (tcgetattr(dest, &term) != 0) {
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FAIL("Failed to get termios for %s", DUMP_TARGET);
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}
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cfmakeraw(&term); // Always successful. Returns void.
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if (tcsetattr(dest, TCSAFLUSH, &term) != 0) {
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FAIL("Failed to set terminal to the raw mode for %s", DUMP_TARGET);
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}
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struct stat statbuf;
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if (fstat(vmcore, &statbuf) == -1) {
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FAIL("Failed to stat %s", DUMP_SOURCE);
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}
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printf("Size is %ld bytes\n", statbuf.st_size);
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// sendfile(2) is faster, can't be used because /proc/vmcore doesn't support splice_read
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size_t dumped = 0;
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char buf[BUF_SIZE];
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int progress = 0; // percentage
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// Disable buffering for better display of the progress
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if (setvbuf(stdout, NULL, _IONBF, 0) != 0) {
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fprintf(stderr, "Failed to disable buffering for stdout: %s\n", strerror(errno));
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// This isn't a critical error. Continue.
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}
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while (dumped < statbuf.st_size) {
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ssize_t read_bytes = read(vmcore, buf, BUF_SIZE);
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if (read_bytes == -1) {
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FAIL("Failed to read from %s", DUMP_SOURCE);
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}
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ssize_t written_bytes = write(dest, buf, read_bytes);
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if (written_bytes == -1) {
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FAIL("Failed to write to %s", DUMP_TARGET);
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}
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dumped += written_bytes;
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int new_progress = dumped * 100 / statbuf.st_size;
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if (new_progress > progress) {
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progress = new_progress;
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printf(".");
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}
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}
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printf("done\n");
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__reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, "kernel panic");
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// Never reach here
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fail:
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printf("Crashdump failed\n");
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return 1;
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}
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