mconsole_kern.c
/*
* Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
* Copyright (C) 2001 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/utsname.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include "init.h"
#include "irq_kern.h"
#include "irq_user.h"
#include "kern_util.h"
#include "mconsole.h"
#include "mconsole_kern.h"
#include "os.h"
static int do_unlink_socket(struct notifier_block *notifier,
unsigned long what, void *data)
{
return mconsole_unlink_socket();
}
static struct notifier_block reboot_notifier = {
.notifier_call = do_unlink_socket,
.priority = 0,
};
/* Safe without explicit locking for now. Tasklets provide their own
* locking, and the interrupt handler is safe because it can't interrupt
* itself and it can only happen on CPU 0.
*/
static LIST_HEAD(mc_requests);
static void mc_work_proc(struct work_struct *unused)
{
struct mconsole_entry *req;
unsigned long flags;
while (!list_empty(&mc_requests)) {
local_irq_save(flags);
req = list_entry(mc_requests.next, struct mconsole_entry, list);
list_del(&req->list);
local_irq_restore(flags);
req->request.cmd->handler(&req->request);
kfree(req);
}
}
static DECLARE_WORK(mconsole_work, mc_work_proc);
static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
{
/* long to avoid size mismatch warnings from gcc */
long fd;
struct mconsole_entry *new;
static struct mc_request req; /* that's OK */
fd = (long) dev_id;
while (mconsole_get_request(fd, &req)) {
if (req.cmd->context == MCONSOLE_INTR)
(*req.cmd->handler)(&req);
else {
new = kmalloc(sizeof(*new), GFP_NOWAIT);
if (new == NULL)
mconsole_reply(&req, "Out of memory", 1, 0);
else {
new->request = req;
new->request.regs = get_irq_regs()->regs;
list_add(&new->list, &mc_requests);
}
}
}
if (!list_empty(&mc_requests))
schedule_work(&mconsole_work);
reactivate_fd(fd, MCONSOLE_IRQ);
return IRQ_HANDLED;
}
void mconsole_version(struct mc_request *req)
{
char version[256];
sprintf(version, "%s %s %s %s %s", utsname()->sysname,
utsname()->nodename, utsname()->release, utsname()->version,
utsname()->machine);
mconsole_reply(req, version, 0, 0);
}
void mconsole_log(struct mc_request *req)
{
int len;
char *ptr = req->request.data;
ptr += strlen("log ");
len = req->len - (ptr - req->request.data);
printk(KERN_WARNING "%.*s", len, ptr);
mconsole_reply(req, "", 0, 0);
}
/* This is a more convoluted version of mconsole_proc, which has some stability
* problems; however, we need it fixed, because it is expected that UML users
* mount HPPFS instead of procfs on /proc. And we want mconsole_proc to still
* show the real procfs content, not the ones from hppfs.*/
#if 0
void mconsole_proc(struct mc_request *req)
{
struct nameidata nd;
struct file_system_type *proc;
struct super_block *super;
struct file *file;
int n, err;
char *ptr = req->request.data, *buf;
ptr += strlen("proc");
while (isspace(*ptr)) ptr++;
proc = get_fs_type("proc");
if (proc == NULL) {
mconsole_reply(req, "procfs not registered", 1, 0);
goto out;
}
super = (*proc->get_sb)(proc, 0, NULL, NULL);
put_filesystem(proc);
if (super == NULL) {
mconsole_reply(req, "Failed to get procfs superblock", 1, 0);
goto out;
}
up_write(&super->s_umount);
nd.path.dentry = super->s_root;
nd.path.mnt = NULL;
nd.flags = O_RDONLY + 1;
nd.last_type = LAST_ROOT;
/* START: it was experienced that the stability problems are closed
* if commenting out these two calls + the below read cycle. To
* make UML crash again, it was enough to readd either one.*/
err = link_path_walk(ptr, &nd);
if (err) {
mconsole_reply(req, "Failed to look up file", 1, 0);
goto out_kill;
}
file = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY);
if (IS_ERR(file)) {
mconsole_reply(req, "Failed to open file", 1, 0);
goto out_kill;
}
/*END*/
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (buf == NULL) {
mconsole_reply(req, "Failed to allocate buffer", 1, 0);
goto out_fput;
}
if ((file->f_op != NULL) && (file->f_op->read != NULL)) {
do {
n = (*file->f_op->read)(file, buf, PAGE_SIZE - 1,
&file->f_pos);
if (n >= 0) {
buf[n] = '\0';
mconsole_reply(req, buf, 0, (n > 0));
}
else {
mconsole_reply(req, "Read of file failed",
1, 0);
goto out_free;
}
} while (n > 0);
}
else mconsole_reply(req, "", 0, 0);
out_free:
kfree(buf);
out_fput:
fput(file);
out_kill:
deactivate_super(super);
out: ;
}
#endif
void mconsole_proc(struct mc_request *req)
{
char path[64];
char *buf;
int len;
int fd;
int first_chunk = 1;
char *ptr = req->request.data;
ptr += strlen("proc");
while (isspace(*ptr))
ptr++;
snprintf(path, sizeof(path), "/proc/%s", ptr);
fd = sys_open(path, 0, 0);
if (fd < 0) {
mconsole_reply(req, "Failed to open file", 1, 0);
printk(KERN_ERR "open %s: %d\n",path,fd);
goto out;
}
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (buf == NULL) {
mconsole_reply(req, "Failed to allocate buffer", 1, 0);
goto out_close;
}
for (;;) {
len = sys_read(fd, buf, PAGE_SIZE-1);
if (len < 0) {
mconsole_reply(req, "Read of file failed", 1, 0);
goto out_free;
}
/* Begin the file content on his own line. */
if (first_chunk) {
mconsole_reply(req, "\n", 0, 1);
first_chunk = 0;
}
if (len == PAGE_SIZE-1) {
buf[len] = '\0';
mconsole_reply(req, buf, 0, 1);
} else {
buf[len] = '\0';
mconsole_reply(req, buf, 0, 0);
break;
}
}
out_free:
kfree(buf);
out_close:
sys_close(fd);
out:
/* nothing */;
}
#define UML_MCONSOLE_HELPTEXT \
"Commands: \n\
version - Get kernel version \n\
help - Print this message \n\
halt - Halt UML \n\
reboot - Reboot UML \n\
config <dev>=<config> - Add a new device to UML; \n\
same syntax as command line \n\
config <dev> - Query the configuration of a device \n\
remove <dev> - Remove a device from UML \n\
sysrq <letter> - Performs the SysRq action controlled by the letter \n\
cad - invoke the Ctrl-Alt-Del handler \n\
stop - pause the UML; it will do nothing until it receives a 'go' \n\
go - continue the UML after a 'stop' \n\
log <string> - make UML enter <string> into the kernel log\n\
proc <file> - returns the contents of the UML's /proc/<file>\n\
stack <pid> - returns the stack of the specified pid\n\
"
void mconsole_help(struct mc_request *req)
{
mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0);
}
void mconsole_halt(struct mc_request *req)
{
mconsole_reply(req, "", 0, 0);
machine_halt();
}
void mconsole_reboot(struct mc_request *req)
{
mconsole_reply(req, "", 0, 0);
machine_restart(NULL);
}
void mconsole_cad(struct mc_request *req)
{
mconsole_reply(req, "", 0, 0);
ctrl_alt_del();
}
void mconsole_go(struct mc_request *req)
{
mconsole_reply(req, "Not stopped", 1, 0);
}
void mconsole_stop(struct mc_request *req)
{
deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
os_set_fd_block(req->originating_fd, 1);
mconsole_reply(req, "stopped", 0, 0);
for (;;) {
if (!mconsole_get_request(req->originating_fd, req))
continue;
if (req->cmd->handler == mconsole_go)
break;
if (req->cmd->handler == mconsole_stop) {
mconsole_reply(req, "Already stopped", 1, 0);
continue;
}
if (req->cmd->handler == mconsole_sysrq) {
struct pt_regs *old_regs;
old_regs = set_irq_regs((struct pt_regs *)&req->regs);
mconsole_sysrq(req);
set_irq_regs(old_regs);
continue;
}
(*req->cmd->handler)(req);
}
os_set_fd_block(req->originating_fd, 0);
reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
mconsole_reply(req, "", 0, 0);
}
static DEFINE_SPINLOCK(mc_devices_lock);
static LIST_HEAD(mconsole_devices);
void mconsole_register_dev(struct mc_device *new)
{
spin_lock(&mc_devices_lock);
BUG_ON(!list_empty(&new->list));
list_add(&new->list, &mconsole_devices);
spin_unlock(&mc_devices_lock);
}
static struct mc_device *mconsole_find_dev(char *name)
{
struct list_head *ele;
struct mc_device *dev;
list_for_each(ele, &mconsole_devices) {
dev = list_entry(ele, struct mc_device, list);
if (!strncmp(name, dev->name, strlen(dev->name)))
return dev;
}
return NULL;
}
#define UNPLUGGED_PER_PAGE \
((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
struct unplugged_pages {
struct list_head list;
void *pages[UNPLUGGED_PER_PAGE];
};
static DEFINE_MUTEX(plug_mem_mutex);
static unsigned long long unplugged_pages_count = 0;
static LIST_HEAD(unplugged_pages);
static int unplug_index = UNPLUGGED_PER_PAGE;
static int mem_config(char *str, char **error_out)
{
unsigned long long diff;
int err = -EINVAL, i, add;
char *ret;
if (str[0] != '=') {
*error_out = "Expected '=' after 'mem'";
goto out;
}
str++;
if (str[0] == '-')
add = 0;
else if (str[0] == '+') {
add = 1;
}
else {
*error_out = "Expected increment to start with '-' or '+'";
goto out;
}
str++;
diff = memparse(str, &ret);
if (*ret != '\0') {
*error_out = "Failed to parse memory increment";
goto out;
}
diff /= PAGE_SIZE;
mutex_lock(&plug_mem_mutex);
for (i = 0; i < diff; i++) {
struct unplugged_pages *unplugged;
void *addr;
if (add) {
if (list_empty(&unplugged_pages))
break;
unplugged = list_entry(unplugged_pages.next,
struct unplugged_pages, list);
if (unplug_index > 0)
addr = unplugged->pages[--unplug_index];
else {
list_del(&unplugged->list);
addr = unplugged;
unplug_index = UNPLUGGED_PER_PAGE;
}
free_page((unsigned long) addr);
unplugged_pages_count--;
}
else {
struct page *page;
page = alloc_page(GFP_ATOMIC);
if (page == NULL)
break;
unplugged = page_address(page);
if (unplug_index == UNPLUGGED_PER_PAGE) {
list_add(&unplugged->list, &unplugged_pages);
unplug_index = 0;
}
else {
struct list_head *entry = unplugged_pages.next;
addr = unplugged;
unplugged = list_entry(entry,
struct unplugged_pages,
list);
err = os_drop_memory(addr, PAGE_SIZE);
if (err) {
printk(KERN_ERR "Failed to release "
"memory - errno = %d\n", err);
*error_out = "Failed to release memory";
goto out_unlock;
}
unplugged->pages[unplug_index++] = addr;
}
unplugged_pages_count++;
}
}
err = 0;
out_unlock:
mutex_unlock(&plug_mem_mutex);
out:
return err;
}
static int mem_get_config(char *name, char *str, int size, char **error_out)
{
char buf[sizeof("18446744073709551615")];
int len = 0;
sprintf(buf, "%ld", uml_physmem);
CONFIG_CHUNK(str, size, len, buf, 1);
return len;
}
static int mem_id(char **str, int *start_out, int *end_out)
{
*start_out = 0;
*end_out = 0;
return 0;
}
static int mem_remove(int n, char **error_out)
{
*error_out = "Memory doesn't support the remove operation";
return -EBUSY;
}
static struct mc_device mem_mc = {
.list = LIST_HEAD_INIT(mem_mc.list),
.name = "mem",
.config = mem_config,
.get_config = mem_get_config,
.id = mem_id,
.remove = mem_remove,
};
static int __init mem_mc_init(void)
{
if (can_drop_memory())
mconsole_register_dev(&mem_mc);
else printk(KERN_ERR "Can't release memory to the host - memory "
"hotplug won't be supported\n");
return 0;
}
__initcall(mem_mc_init);
#define CONFIG_BUF_SIZE 64
static void mconsole_get_config(int (*get_config)(char *, char *, int,
char **),
struct mc_request *req, char *name)
{
char default_buf[CONFIG_BUF_SIZE], *error, *buf;
int n, size;
if (get_config == NULL) {
mconsole_reply(req, "No get_config routine defined", 1, 0);
return;
}
error = NULL;
size = ARRAY_SIZE(default_buf);
buf = default_buf;
while (1) {
n = (*get_config)(name, buf, size, &error);
if (error != NULL) {
mconsole_reply(req, error, 1, 0);
goto out;
}
if (n <= size) {
mconsole_reply(req, buf, 0, 0);
goto out;
}
if (buf != default_buf)
kfree(buf);
size = n;
buf = kmalloc(size, GFP_KERNEL);
if (buf == NULL) {
mconsole_reply(req, "Failed to allocate buffer", 1, 0);
return;
}
}
out:
if (buf != default_buf)
kfree(buf);
}
void mconsole_config(struct mc_request *req)
{
struct mc_device *dev;
char *ptr = req->request.data, *name, *error_string = "";
int err;
ptr += strlen("config");
while (isspace(*ptr))
ptr++;
dev = mconsole_find_dev(ptr);
if (dev == NULL) {
mconsole_reply(req, "Bad configuration option", 1, 0);
return;
}
name = &ptr[strlen(dev->name)];
ptr = name;
while ((*ptr != '=') && (*ptr != '\0'))
ptr++;
if (*ptr == '=') {
err = (*dev->config)(name, &error_string);
mconsole_reply(req, error_string, err, 0);
}
else mconsole_get_config(dev->get_config, req, name);
}
void mconsole_remove(struct mc_request *req)
{
struct mc_device *dev;
char *ptr = req->request.data, *err_msg = "";
char error[256];
int err, start, end, n;
ptr += strlen("remove");
while (isspace(*ptr)) ptr++;
dev = mconsole_find_dev(ptr);
if (dev == NULL) {
mconsole_reply(req, "Bad remove option", 1, 0);
return;
}
ptr = &ptr[strlen(dev->name)];
err = 1;
n = (*dev->id)(&ptr, &start, &end);
if (n < 0) {
err_msg = "Couldn't parse device number";
goto out;
}
else if ((n < start) || (n > end)) {
sprintf(error, "Invalid device number - must be between "
"%d and %d", start, end);
err_msg = error;
goto out;
}
err_msg = NULL;
err = (*dev->remove)(n, &err_msg);
switch(err) {
case 0:
err_msg = "";
break;
case -ENODEV:
if (err_msg == NULL)
err_msg = "Device doesn't exist";
break;
case -EBUSY:
if (err_msg == NULL)
err_msg = "Device is currently open";
break;
default:
break;
}
out:
mconsole_reply(req, err_msg, err, 0);
}
struct mconsole_output {
struct list_head list;
struct mc_request *req;
};
static DEFINE_SPINLOCK(client_lock);
static LIST_HEAD(clients);
static char console_buf[MCONSOLE_MAX_DATA];
static void console_write(struct console *console, const char *string,
unsigned int len)
{
struct list_head *ele;
int n;
if (list_empty(&clients))
return;
while (len > 0) {
n = min((size_t) len, ARRAY_SIZE(console_buf));
strncpy(console_buf, string, n);
string += n;
len -= n;
list_for_each(ele, &clients) {
struct mconsole_output *entry;
entry = list_entry(ele, struct mconsole_output, list);
mconsole_reply_len(entry->req, console_buf, n, 0, 1);
}
}
}
static struct console mc_console = { .name = "mc",
.write = console_write,
.flags = CON_ENABLED,
.index = -1 };
static int mc_add_console(void)
{
register_console(&mc_console);
return 0;
}
late_initcall(mc_add_console);
static void with_console(struct mc_request *req, void (*proc)(void *),
void *arg)
{
struct mconsole_output entry;
unsigned long flags;
entry.req = req;
spin_lock_irqsave(&client_lock, flags);
list_add(&entry.list, &clients);
spin_unlock_irqrestore(&client_lock, flags);
(*proc)(arg);
mconsole_reply_len(req, "", 0, 0, 0);
spin_lock_irqsave(&client_lock, flags);
list_del(&entry.list);
spin_unlock_irqrestore(&client_lock, flags);
}
#ifdef CONFIG_MAGIC_SYSRQ
#include <linux/sysrq.h>
static void sysrq_proc(void *arg)
{
char *op = arg;
handle_sysrq(*op, NULL);
}
void mconsole_sysrq(struct mc_request *req)
{
char *ptr = req->request.data;
ptr += strlen("sysrq");
while (isspace(*ptr)) ptr++;
/*
* With 'b', the system will shut down without a chance to reply,
* so in this case, we reply first.
*/
if (*ptr == 'b')
mconsole_reply(req, "", 0, 0);
with_console(req, sysrq_proc, ptr);
}
#else
void mconsole_sysrq(struct mc_request *req)
{
mconsole_reply(req, "Sysrq not compiled in", 1, 0);
}
#endif
static void stack_proc(void *arg)
{
struct task_struct *from = current, *to = arg;
to->thread.saved_task = from;
switch_to(from, to, from);
}
/*
* Mconsole stack trace
* Added by Allan Graves, Jeff Dike
* Dumps a stacks registers to the linux console.
* Usage stack <pid>.
*/
void mconsole_stack(struct mc_request *req)
{
char *ptr = req->request.data;
int pid_requested= -1;
struct task_struct *to = NULL;
/*
* Would be nice:
* 1) Send showregs output to mconsole.
* 2) Add a way to stack dump all pids.
*/
ptr += strlen("stack");
while (isspace(*ptr))
ptr++;
/*
* Should really check for multiple pids or reject bad args here
*/
/* What do the arguments in mconsole_reply mean? */
if (sscanf(ptr, "%d", &pid_requested) == 0) {
mconsole_reply(req, "Please specify a pid", 1, 0);
return;
}
to = find_task_by_pid_ns(pid_requested, &init_pid_ns);
if ((to == NULL) || (pid_requested == 0)) {
mconsole_reply(req, "Couldn't find that pid", 1, 0);
return;
}
with_console(req, stack_proc, to);
}
/*
* Changed by mconsole_setup, which is __setup, and called before SMP is
* active.
*/
static char *notify_socket = NULL;
static int __init mconsole_init(void)
{
/* long to avoid size mismatch warnings from gcc */
long sock;
int err;
char file[256];
if (umid_file_name("mconsole", file, sizeof(file)))
return -1;
snprintf(mconsole_socket_name, sizeof(file), "%s", file);
sock = os_create_unix_socket(file, sizeof(file), 1);
if (sock < 0) {
printk(KERN_ERR "Failed to initialize management console\n");
return 1;
}
if (os_set_fd_block(sock, 0))
goto out;
register_reboot_notifier(&reboot_notifier);
err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
"mconsole", (void *)sock);
if (err) {
printk(KERN_ERR "Failed to get IRQ for management console\n");
goto out;
}
if (notify_socket != NULL) {
notify_socket = kstrdup(notify_socket, GFP_KERNEL);
if (notify_socket != NULL)
mconsole_notify(notify_socket, MCONSOLE_SOCKET,
mconsole_socket_name,
strlen(mconsole_socket_name) + 1);
else printk(KERN_ERR "mconsole_setup failed to strdup "
"string\n");
}
printk(KERN_INFO "mconsole (version %d) initialized on %s\n",
MCONSOLE_VERSION, mconsole_socket_name);
return 0;
out:
os_close_file(sock);
return 1;
}
__initcall(mconsole_init);
static int write_proc_mconsole(struct file *file, const char __user *buffer,
unsigned long count, void *data)
{
char *buf;
buf = kmalloc(count + 1, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
if (copy_from_user(buf, buffer, count)) {
count = -EFAULT;
goto out;
}
buf[count] = '\0';
mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
out:
kfree(buf);
return count;
}
static int create_proc_mconsole(void)
{
struct proc_dir_entry *ent;
if (notify_socket == NULL)
return 0;
ent = create_proc_entry("mconsole", S_IFREG | 0200, NULL);
if (ent == NULL) {
printk(KERN_INFO "create_proc_mconsole : create_proc_entry "
"failed\n");
return 0;
}
ent->read_proc = NULL;
ent->write_proc = write_proc_mconsole;
return 0;
}
static DEFINE_SPINLOCK(notify_spinlock);
void lock_notify(void)
{
spin_lock(¬ify_spinlock);
}
void unlock_notify(void)
{
spin_unlock(¬ify_spinlock);
}
__initcall(create_proc_mconsole);
#define NOTIFY "notify:"
static int mconsole_setup(char *str)
{
if (!strncmp(str, NOTIFY, strlen(NOTIFY))) {
str += strlen(NOTIFY);
notify_socket = str;
}
else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
return 1;
}
__setup("mconsole=", mconsole_setup);
__uml_help(mconsole_setup,
"mconsole=notify:<socket>\n"
" Requests that the mconsole driver send a message to the named Unix\n"
" socket containing the name of the mconsole socket. This also serves\n"
" to notify outside processes when UML has booted far enough to respond\n"
" to mconsole requests.\n\n"
);
static int notify_panic(struct notifier_block *self, unsigned long unused1,
void *ptr)
{
char *message = ptr;
if (notify_socket == NULL)
return 0;
mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
strlen(message) + 1);
return 0;
}
static struct notifier_block panic_exit_notifier = {
.notifier_call = notify_panic,
.next = NULL,
.priority = 1
};
static int add_notifier(void)
{
atomic_notifier_chain_register(&panic_notifier_list,
&panic_exit_notifier);
return 0;
}
__initcall(add_notifier);
char *mconsole_notify_socket(void)
{
return notify_socket;
}
EXPORT_SYMBOL(mconsole_notify_socket);