mconsole_kern.c

来自「LINUX 2.6.17.4的源码」· C语言 代码 · 共 914 行 · 第 1/2 页

/*
 * Copyright (C) 2001 Lennert Buytenhek ([e-mail])
 * Copyright (C) 2001 - 2003 Jeff Dike ([e-mail])
 * Licensed under the GPL
 */

#include "linux/kernel.h"
#include "linux/slab.h"
#include "linux/init.h"
#include "linux/notifier.h"
#include "linux/reboot.h"
#include "linux/utsname.h"
#include "linux/ctype.h"
#include "linux/interrupt.h"
#include "linux/sysrq.h"
#include "linux/workqueue.h"
#include "linux/module.h"
#include "linux/file.h"
#include "linux/fs.h"
#include "linux/namei.h"
#include "linux/proc_fs.h"
#include "linux/syscalls.h"
#include "linux/list.h"
#include "linux/mm.h"
#include "linux/console.h"
#include "asm/irq.h"
#include "asm/uaccess.h"
#include "user_util.h"
#include "kern_util.h"
#include "kern.h"
#include "mconsole.h"
#include "mconsole_kern.h"
#include "irq_user.h"
#include "init.h"
#include "os.h"
#include "umid.h"
#include "irq_kern.h"
#include "choose-mode.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(void *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, NULL);

static irqreturn_t mconsole_interrupt(int irq, void *dev_id,
				      struct pt_regs *regs)
{
	/* long to avoid size mismatch warnings from gcc */
	long fd;
	struct mconsole_entry *new;
	struct mc_request req;

	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;
				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", system_utsname.sysname,
		system_utsname.nodename, system_utsname.release,
		system_utsname.version, system_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("%.*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.dentry = super->s_root;
	nd.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.dentry, nd.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("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);
}

extern void ctrl_alt_del(void);

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, "", 0, 0);
	while(mconsole_get_request(req->originating_fd, req)){
		if(req->cmd->handler == mconsole_go) break;
		(*req->cmd->handler)(req);
	}
	os_set_fd_block(req->originating_fd, 0);
	reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
	mconsole_reply(req, "", 0, 0);
}

/* This list is populated by __initcall routines. */

static LIST_HEAD(mconsole_devices);

void mconsole_register_dev(struct mc_device *new)
{
	list_add(&new->list, &mconsole_devices);
}

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 unsigned long long unplugged_pages_count = 0;
static struct list_head unplugged_pages = LIST_HEAD_INIT(unplugged_pages);
static int unplug_index = UNPLUGGED_PER_PAGE;

static int mem_config(char *str)
{
	unsigned long long diff;
	int err = -EINVAL, i, add;
	char *ret;

	if(str[0] != '=')
		goto out;

	str++;
	if(str[0] == '-')
		add = 0;
	else if(str[0] == '+'){
		add = 1;
	}
	else goto out;

	str++;
	diff = memparse(str, &ret);
	if(*ret != '\0')
		goto out;

	diff /= PAGE_SIZE;

	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);
				unplugged->pages[unplug_index++] = addr;
				err = os_drop_memory(addr, PAGE_SIZE);
				if(err)
					printk("Failed to release memory - "
					       "errno = %d\n", err);
			}

			unplugged_pages_count++;
		}
	}

	err = 0;
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;