1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
4 * Copyright (C) 2001 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
7 #include <linux/console.h>
8 #include <linux/ctype.h>
9 #include <linux/string.h>
10 #include <linux/interrupt.h>
11 #include <linux/list.h>
13 #include <linux/module.h>
14 #include <linux/notifier.h>
15 #include <linux/panic_notifier.h>
16 #include <linux/reboot.h>
17 #include <linux/sched/debug.h>
18 #include <linux/proc_fs.h>
19 #include <linux/slab.h>
20 #include <linux/syscalls.h>
21 #include <linux/utsname.h>
22 #include <linux/socket.h>
24 #include <linux/workqueue.h>
25 #include <linux/mutex.h>
27 #include <linux/mount.h>
28 #include <linux/file.h>
29 #include <linux/uaccess.h>
30 #include <asm/switch_to.h>
35 #include <kern_util.h>
37 #include "mconsole_kern.h"
40 static struct vfsmount *proc_mnt = NULL;
42 static int do_unlink_socket(struct notifier_block *notifier,
43 unsigned long what, void *data)
45 return mconsole_unlink_socket();
49 static struct notifier_block reboot_notifier = {
50 .notifier_call = do_unlink_socket,
54 /* Safe without explicit locking for now. Tasklets provide their own
55 * locking, and the interrupt handler is safe because it can't interrupt
56 * itself and it can only happen on CPU 0.
59 static LIST_HEAD(mc_requests);
61 static void mc_work_proc(struct work_struct *unused)
63 struct mconsole_entry *req;
66 while (!list_empty(&mc_requests)) {
67 local_irq_save(flags);
68 req = list_entry(mc_requests.next, struct mconsole_entry, list);
70 local_irq_restore(flags);
71 req->request.cmd->handler(&req->request);
76 static DECLARE_WORK(mconsole_work, mc_work_proc);
78 static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
80 /* long to avoid size mismatch warnings from gcc */
82 struct mconsole_entry *new;
83 static struct mc_request req; /* that's OK */
86 while (mconsole_get_request(fd, &req)) {
87 if (req.cmd->context == MCONSOLE_INTR)
88 (*req.cmd->handler)(&req);
90 new = kmalloc(sizeof(*new), GFP_NOWAIT);
92 mconsole_reply(&req, "Out of memory", 1, 0);
95 new->request.regs = get_irq_regs()->regs;
96 list_add(&new->list, &mc_requests);
100 if (!list_empty(&mc_requests))
101 schedule_work(&mconsole_work);
105 void mconsole_version(struct mc_request *req)
109 sprintf(version, "%s %s %s %s %s", utsname()->sysname,
110 utsname()->nodename, utsname()->release, utsname()->version,
112 mconsole_reply(req, version, 0, 0);
115 void mconsole_log(struct mc_request *req)
118 char *ptr = req->request.data;
120 ptr += strlen("log ");
122 len = req->len - (ptr - req->request.data);
123 printk(KERN_WARNING "%.*s", len, ptr);
124 mconsole_reply(req, "", 0, 0);
127 void mconsole_proc(struct mc_request *req)
129 struct vfsmount *mnt = proc_mnt;
134 char *ptr = req->request.data;
137 ptr += strlen("proc");
138 ptr = skip_spaces(ptr);
141 mconsole_reply(req, "Proc not available", 1, 0);
144 file = file_open_root_mnt(mnt, ptr, O_RDONLY, 0);
146 mconsole_reply(req, "Failed to open file", 1, 0);
147 printk(KERN_ERR "open /proc/%s: %ld\n", ptr, PTR_ERR(file));
151 buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
153 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
158 len = kernel_read(file, buf, PAGE_SIZE - 1, &pos);
160 mconsole_reply(req, "Read of file failed", 1, 0);
163 /* Begin the file content on his own line. */
165 mconsole_reply(req, "\n", 0, 1);
169 mconsole_reply(req, buf, 0, (len > 0));
178 #define UML_MCONSOLE_HELPTEXT \
180 version - Get kernel version \n\
181 help - Print this message \n\
183 reboot - Reboot UML \n\
184 config <dev>=<config> - Add a new device to UML; \n\
185 same syntax as command line \n\
186 config <dev> - Query the configuration of a device \n\
187 remove <dev> - Remove a device from UML \n\
188 sysrq <letter> - Performs the SysRq action controlled by the letter \n\
189 cad - invoke the Ctrl-Alt-Del handler \n\
190 stop - pause the UML; it will do nothing until it receives a 'go' \n\
191 go - continue the UML after a 'stop' \n\
192 log <string> - make UML enter <string> into the kernel log\n\
193 proc <file> - returns the contents of the UML's /proc/<file>\n\
194 stack <pid> - returns the stack of the specified pid\n\
197 void mconsole_help(struct mc_request *req)
199 mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0);
202 void mconsole_halt(struct mc_request *req)
204 mconsole_reply(req, "", 0, 0);
208 void mconsole_reboot(struct mc_request *req)
210 mconsole_reply(req, "", 0, 0);
211 machine_restart(NULL);
214 void mconsole_cad(struct mc_request *req)
216 mconsole_reply(req, "", 0, 0);
220 void mconsole_go(struct mc_request *req)
222 mconsole_reply(req, "Not stopped", 1, 0);
225 void mconsole_stop(struct mc_request *req)
228 os_set_fd_block(req->originating_fd, 1);
229 mconsole_reply(req, "stopped", 0, 0);
231 if (!mconsole_get_request(req->originating_fd, req))
233 if (req->cmd->handler == mconsole_go)
235 if (req->cmd->handler == mconsole_stop) {
236 mconsole_reply(req, "Already stopped", 1, 0);
239 if (req->cmd->handler == mconsole_sysrq) {
240 struct pt_regs *old_regs;
241 old_regs = set_irq_regs((struct pt_regs *)&req->regs);
243 set_irq_regs(old_regs);
246 (*req->cmd->handler)(req);
248 os_set_fd_block(req->originating_fd, 0);
249 mconsole_reply(req, "", 0, 0);
253 static DEFINE_SPINLOCK(mc_devices_lock);
254 static LIST_HEAD(mconsole_devices);
256 void mconsole_register_dev(struct mc_device *new)
258 spin_lock(&mc_devices_lock);
259 BUG_ON(!list_empty(&new->list));
260 list_add(&new->list, &mconsole_devices);
261 spin_unlock(&mc_devices_lock);
264 static struct mc_device *mconsole_find_dev(char *name)
266 struct list_head *ele;
267 struct mc_device *dev;
269 list_for_each(ele, &mconsole_devices) {
270 dev = list_entry(ele, struct mc_device, list);
271 if (!strncmp(name, dev->name, strlen(dev->name)))
277 #define UNPLUGGED_PER_PAGE \
278 ((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
280 struct unplugged_pages {
281 struct list_head list;
282 void *pages[UNPLUGGED_PER_PAGE];
285 static DEFINE_MUTEX(plug_mem_mutex);
286 static unsigned long long unplugged_pages_count = 0;
287 static LIST_HEAD(unplugged_pages);
288 static int unplug_index = UNPLUGGED_PER_PAGE;
290 static int mem_config(char *str, char **error_out)
292 unsigned long long diff;
293 int err = -EINVAL, i, add;
297 *error_out = "Expected '=' after 'mem'";
304 else if (str[0] == '+') {
308 *error_out = "Expected increment to start with '-' or '+'";
313 diff = memparse(str, &ret);
315 *error_out = "Failed to parse memory increment";
321 mutex_lock(&plug_mem_mutex);
322 for (i = 0; i < diff; i++) {
323 struct unplugged_pages *unplugged;
327 if (list_empty(&unplugged_pages))
330 unplugged = list_entry(unplugged_pages.next,
331 struct unplugged_pages, list);
332 if (unplug_index > 0)
333 addr = unplugged->pages[--unplug_index];
335 list_del(&unplugged->list);
337 unplug_index = UNPLUGGED_PER_PAGE;
340 free_page((unsigned long) addr);
341 unplugged_pages_count--;
346 page = alloc_page(GFP_ATOMIC);
350 unplugged = page_address(page);
351 if (unplug_index == UNPLUGGED_PER_PAGE) {
352 list_add(&unplugged->list, &unplugged_pages);
356 struct list_head *entry = unplugged_pages.next;
359 unplugged = list_entry(entry,
360 struct unplugged_pages,
362 err = os_drop_memory(addr, PAGE_SIZE);
364 printk(KERN_ERR "Failed to release "
365 "memory - errno = %d\n", err);
366 *error_out = "Failed to release memory";
369 unplugged->pages[unplug_index++] = addr;
372 unplugged_pages_count++;
378 mutex_unlock(&plug_mem_mutex);
383 static int mem_get_config(char *name, char *str, int size, char **error_out)
385 char buf[sizeof("18446744073709551615")];
388 sprintf(buf, "%ld", uml_physmem);
389 CONFIG_CHUNK(str, size, len, buf, 1);
394 static int mem_id(char **str, int *start_out, int *end_out)
402 static int mem_remove(int n, char **error_out)
404 *error_out = "Memory doesn't support the remove operation";
408 static struct mc_device mem_mc = {
409 .list = LIST_HEAD_INIT(mem_mc.list),
411 .config = mem_config,
412 .get_config = mem_get_config,
414 .remove = mem_remove,
417 static int __init mem_mc_init(void)
419 if (can_drop_memory())
420 mconsole_register_dev(&mem_mc);
421 else printk(KERN_ERR "Can't release memory to the host - memory "
422 "hotplug won't be supported\n");
426 __initcall(mem_mc_init);
428 #define CONFIG_BUF_SIZE 64
430 static void mconsole_get_config(int (*get_config)(char *, char *, int,
432 struct mc_request *req, char *name)
434 char default_buf[CONFIG_BUF_SIZE], *error, *buf;
437 if (get_config == NULL) {
438 mconsole_reply(req, "No get_config routine defined", 1, 0);
443 size = ARRAY_SIZE(default_buf);
447 n = (*get_config)(name, buf, size, &error);
449 mconsole_reply(req, error, 1, 0);
454 mconsole_reply(req, buf, 0, 0);
458 if (buf != default_buf)
462 buf = kmalloc(size, GFP_KERNEL);
464 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
469 if (buf != default_buf)
473 void mconsole_config(struct mc_request *req)
475 struct mc_device *dev;
476 char *ptr = req->request.data, *name, *error_string = "";
479 ptr += strlen("config");
480 ptr = skip_spaces(ptr);
481 dev = mconsole_find_dev(ptr);
483 mconsole_reply(req, "Bad configuration option", 1, 0);
487 name = &ptr[strlen(dev->name)];
489 while ((*ptr != '=') && (*ptr != '\0'))
493 err = (*dev->config)(name, &error_string);
494 mconsole_reply(req, error_string, err, 0);
496 else mconsole_get_config(dev->get_config, req, name);
499 void mconsole_remove(struct mc_request *req)
501 struct mc_device *dev;
502 char *ptr = req->request.data, *err_msg = "";
504 int err, start, end, n;
506 ptr += strlen("remove");
507 ptr = skip_spaces(ptr);
508 dev = mconsole_find_dev(ptr);
510 mconsole_reply(req, "Bad remove option", 1, 0);
514 ptr = &ptr[strlen(dev->name)];
517 n = (*dev->id)(&ptr, &start, &end);
519 err_msg = "Couldn't parse device number";
522 else if ((n < start) || (n > end)) {
523 sprintf(error, "Invalid device number - must be between "
524 "%d and %d", start, end);
530 err = (*dev->remove)(n, &err_msg);
537 err_msg = "Device doesn't exist";
541 err_msg = "Device is currently open";
547 mconsole_reply(req, err_msg, err, 0);
550 struct mconsole_output {
551 struct list_head list;
552 struct mc_request *req;
555 static DEFINE_SPINLOCK(client_lock);
556 static LIST_HEAD(clients);
557 static char console_buf[MCONSOLE_MAX_DATA];
559 static void console_write(struct console *console, const char *string,
562 struct list_head *ele;
565 if (list_empty(&clients))
569 n = min((size_t) len, ARRAY_SIZE(console_buf));
570 strncpy(console_buf, string, n);
574 list_for_each(ele, &clients) {
575 struct mconsole_output *entry;
577 entry = list_entry(ele, struct mconsole_output, list);
578 mconsole_reply_len(entry->req, console_buf, n, 0, 1);
583 static struct console mc_console = { .name = "mc",
584 .write = console_write,
585 .flags = CON_ENABLED,
588 static int mc_add_console(void)
590 register_console(&mc_console);
594 late_initcall(mc_add_console);
596 static void with_console(struct mc_request *req, void (*proc)(void *),
599 struct mconsole_output entry;
603 spin_lock_irqsave(&client_lock, flags);
604 list_add(&entry.list, &clients);
605 spin_unlock_irqrestore(&client_lock, flags);
609 mconsole_reply_len(req, "", 0, 0, 0);
611 spin_lock_irqsave(&client_lock, flags);
612 list_del(&entry.list);
613 spin_unlock_irqrestore(&client_lock, flags);
616 #ifdef CONFIG_MAGIC_SYSRQ
618 #include <linux/sysrq.h>
620 static void sysrq_proc(void *arg)
626 void mconsole_sysrq(struct mc_request *req)
628 char *ptr = req->request.data;
630 ptr += strlen("sysrq");
631 ptr = skip_spaces(ptr);
634 * With 'b', the system will shut down without a chance to reply,
635 * so in this case, we reply first.
638 mconsole_reply(req, "", 0, 0);
640 with_console(req, sysrq_proc, ptr);
643 void mconsole_sysrq(struct mc_request *req)
645 mconsole_reply(req, "Sysrq not compiled in", 1, 0);
649 static void stack_proc(void *arg)
651 struct task_struct *task = arg;
653 show_stack(task, NULL, KERN_INFO);
657 * Mconsole stack trace
658 * Added by Allan Graves, Jeff Dike
659 * Dumps a stacks registers to the linux console.
662 void mconsole_stack(struct mc_request *req)
664 char *ptr = req->request.data;
665 int pid_requested= -1;
666 struct task_struct *to = NULL;
670 * 1) Send showregs output to mconsole.
671 * 2) Add a way to stack dump all pids.
674 ptr += strlen("stack");
675 ptr = skip_spaces(ptr);
678 * Should really check for multiple pids or reject bad args here
680 /* What do the arguments in mconsole_reply mean? */
681 if (sscanf(ptr, "%d", &pid_requested) == 0) {
682 mconsole_reply(req, "Please specify a pid", 1, 0);
686 to = find_task_by_pid_ns(pid_requested, &init_pid_ns);
687 if ((to == NULL) || (pid_requested == 0)) {
688 mconsole_reply(req, "Couldn't find that pid", 1, 0);
691 with_console(req, stack_proc, to);
694 static int __init mount_proc(void)
696 struct file_system_type *proc_fs_type;
697 struct vfsmount *mnt;
699 proc_fs_type = get_fs_type("proc");
703 mnt = kern_mount(proc_fs_type);
704 put_filesystem(proc_fs_type);
713 * Changed by mconsole_setup, which is __setup, and called before SMP is
716 static char *notify_socket = NULL;
718 static int __init mconsole_init(void)
720 /* long to avoid size mismatch warnings from gcc */
723 char file[UNIX_PATH_MAX];
727 if (umid_file_name("mconsole", file, sizeof(file)))
729 snprintf(mconsole_socket_name, sizeof(file), "%s", file);
731 sock = os_create_unix_socket(file, sizeof(file), 1);
733 printk(KERN_ERR "Failed to initialize management console\n");
736 if (os_set_fd_block(sock, 0))
739 register_reboot_notifier(&reboot_notifier);
741 err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
742 IRQF_SHARED, "mconsole", (void *)sock);
744 printk(KERN_ERR "Failed to get IRQ for management console\n");
748 if (notify_socket != NULL) {
749 notify_socket = kstrdup(notify_socket, GFP_KERNEL);
750 if (notify_socket != NULL)
751 mconsole_notify(notify_socket, MCONSOLE_SOCKET,
752 mconsole_socket_name,
753 strlen(mconsole_socket_name) + 1);
754 else printk(KERN_ERR "mconsole_setup failed to strdup "
758 printk(KERN_INFO "mconsole (version %d) initialized on %s\n",
759 MCONSOLE_VERSION, mconsole_socket_name);
767 __initcall(mconsole_init);
769 static ssize_t mconsole_proc_write(struct file *file,
770 const char __user *buffer, size_t count, loff_t *pos)
774 buf = memdup_user_nul(buffer, count);
778 mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
783 static const struct proc_ops mconsole_proc_ops = {
784 .proc_write = mconsole_proc_write,
785 .proc_lseek = noop_llseek,
788 static int create_proc_mconsole(void)
790 struct proc_dir_entry *ent;
792 if (notify_socket == NULL)
795 ent = proc_create("mconsole", 0200, NULL, &mconsole_proc_ops);
797 printk(KERN_INFO "create_proc_mconsole : proc_create failed\n");
803 static DEFINE_SPINLOCK(notify_spinlock);
805 void lock_notify(void)
807 spin_lock(¬ify_spinlock);
810 void unlock_notify(void)
812 spin_unlock(¬ify_spinlock);
815 __initcall(create_proc_mconsole);
817 #define NOTIFY "notify:"
819 static int mconsole_setup(char *str)
821 if (!strncmp(str, NOTIFY, strlen(NOTIFY))) {
822 str += strlen(NOTIFY);
825 else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
829 __setup("mconsole=", mconsole_setup);
831 __uml_help(mconsole_setup,
832 "mconsole=notify:<socket>\n"
833 " Requests that the mconsole driver send a message to the named Unix\n"
834 " socket containing the name of the mconsole socket. This also serves\n"
835 " to notify outside processes when UML has booted far enough to respond\n"
836 " to mconsole requests.\n\n"
839 static int notify_panic(struct notifier_block *self, unsigned long unused1,
844 if (notify_socket == NULL)
847 mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
848 strlen(message) + 1);
852 static struct notifier_block panic_exit_notifier = {
853 .notifier_call = notify_panic,
858 static int add_notifier(void)
860 atomic_notifier_chain_register(&panic_notifier_list,
861 &panic_exit_notifier);
865 __initcall(add_notifier);
867 char *mconsole_notify_socket(void)
869 return notify_socket;
872 EXPORT_SYMBOL(mconsole_notify_socket);