[PATCH] Add GFP_NOWAIT

[mirror_ubuntu-zesty-kernel.git] / arch / um / drivers / mconsole_kern.c

/*
 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
 * Copyright (C) 2001 - 2003 Jeff Dike (jdike@addtoit.com)
 * 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_save_flags(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_ATOMIC);
                        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){
                                INIT_LIST_HEAD(&unplugged->list);
                                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;
        *end_out = 0;

        return 0;
}

static int mem_remove(int n)
{
        return -EBUSY;
}

static struct mc_device mem_mc = {
        .name           = "mem",
        .config         = mem_config,
        .get_config     = mem_get_config,
        .id             = mem_id,
        .remove         = mem_remove,
};

static int mem_mc_init(void)
{
        if(can_drop_memory())
                mconsole_register_dev(&mem_mc);
        else printk("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 = sizeof(default_buf)/sizeof(default_buf[0]);
        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;
        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);
                mconsole_reply(req, "", 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 = (*dev->remove)(n);
        switch(err){
        case -ENODEV:
                err_msg = "Device doesn't exist";
                break;
        case -EBUSY:
                err_msg = "Device is currently open";
                break;
        default:
                break;
        }
out:
        mconsole_reply(req, err_msg, err, 0);
}

static DEFINE_SPINLOCK(console_lock);
static LIST_HEAD(clients);
static char console_buf[MCONSOLE_MAX_DATA];
static int console_index = 0;

static void console_write(struct console *console, const char *string,
                          unsigned len)
{
        struct list_head *ele;
        int n;

        if(list_empty(&clients))
                return;

        while(1){
                n = min((size_t)len, ARRAY_SIZE(console_buf) - console_index);
                strncpy(&console_buf[console_index], string, n);
                console_index += n;
                string += n;
                len -= n;
                if(len == 0)
                        return;

                list_for_each(ele, &clients){
                        struct mconsole_entry *entry;

                        entry = list_entry(ele, struct mconsole_entry, list);
                        mconsole_reply_len(&entry->request, console_buf,
                                           console_index, 0, 1);
                }

                console_index = 0;
        }
}

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_entry entry;
        unsigned long flags;

        INIT_LIST_HEAD(&entry.list);
        entry.request = *req;
        list_add(&entry.list, &clients);
        spin_lock_irqsave(&console_lock, flags);

        (*proc)(arg);

        mconsole_reply_len(req, console_buf, console_index, 0, 0);
        console_index = 0;

        spin_unlock_irqrestore(&console_lock, flags);
        list_del(&entry.list);
}

#ifdef CONFIG_MAGIC_SYSRQ
static void sysrq_proc(void *arg)
{
        char *op = arg;

        handle_sysrq(*op, &current->thread.regs, 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

#ifdef CONFIG_MODE_SKAS

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>.
 */
static void do_stack_trace(struct mc_request *req)
{
        char *ptr = req->request.data;
        int pid_requested= -1;
        struct task_struct *from = NULL;
        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;
        }

        from = current;

        to = find_task_by_pid(pid_requested);
        if((to == NULL) || (pid_requested == 0)) {
                mconsole_reply(req, "Couldn't find that pid", 1, 0);
                return;
        }
        with_console(req, stack_proc, to);
}
#endif /* CONFIG_MODE_SKAS */

void mconsole_stack(struct mc_request *req)
{
        /* This command doesn't work in TT mode, so let's check and then
         * get out of here
         */
        CHOOSE_MODE(mconsole_reply(req, "Sorry, this doesn't work in TT mode",
                                   1, 0),
                    do_stack_trace(req));
}

/* Changed by mconsole_setup, which is __setup, and called before SMP is
 * active.
 */
static char *notify_socket = NULL;

static int 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("Failed to initialize management console\n");
                return(1);
        }

        register_reboot_notifier(&reboot_notifier);

        err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
                             SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM,
                             "mconsole", (void *)sock);
        if (err){
                printk("Failed to get IRQ for management console\n");
                return(1);
        }

        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("mconsole (version %d) initialized on %s\n",
               MCONSOLE_VERSION, mconsole_socket_name);
        return(0);
}

__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(&notify_spinlock);
}

void unlock_notify(void)
{
        spin_unlock(&notify_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);