mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race

[linux/fpc-iii.git] / arch / tile / kernel / hardwall.c

/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 */

#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/rwsem.h>
#include <linux/kprobes.h>
#include <linux/sched.h>
#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <linux/smp.h>
#include <linux/cdev.h>
#include <linux/compat.h>
#include <asm/hardwall.h>
#include <asm/traps.h>
#include <asm/siginfo.h>
#include <asm/irq_regs.h>

#include <arch/interrupts.h>
#include <arch/spr_def.h>


/*
 * Implement a per-cpu "hardwall" resource class such as UDN or IPI.
 * We use "hardwall" nomenclature throughout for historical reasons.
 * The lock here controls access to the list data structure as well as
 * to the items on the list.
 */
struct hardwall_type {
        int index;
        int is_xdn;
        int is_idn;
        int disabled;
        const char *name;
        struct list_head list;
        spinlock_t lock;
        struct proc_dir_entry *proc_dir;
};

enum hardwall_index {
        HARDWALL_UDN = 0,
#ifndef __tilepro__
        HARDWALL_IDN = 1,
        HARDWALL_IPI = 2,
#endif
        _HARDWALL_TYPES
};

static struct hardwall_type hardwall_types[] = {
        {  /* user-space access to UDN */
                0,
                1,
                0,
                0,
                "udn",
                LIST_HEAD_INIT(hardwall_types[HARDWALL_UDN].list),
                __SPIN_LOCK_UNLOCKED(hardwall_types[HARDWALL_UDN].lock),
                NULL
        },
#ifndef __tilepro__
        {  /* user-space access to IDN */
                1,
                1,
                1,
                1,  /* disabled pending hypervisor support */
                "idn",
                LIST_HEAD_INIT(hardwall_types[HARDWALL_IDN].list),
                __SPIN_LOCK_UNLOCKED(hardwall_types[HARDWALL_IDN].lock),
                NULL
        },
        {  /* access to user-space IPI */
                2,
                0,
                0,
                0,
                "ipi",
                LIST_HEAD_INIT(hardwall_types[HARDWALL_IPI].list),
                __SPIN_LOCK_UNLOCKED(hardwall_types[HARDWALL_IPI].lock),
                NULL
        },
#endif
};

/*
 * This data structure tracks the cpu data, etc., associated
 * one-to-one with a "struct file *" from opening a hardwall device file.
 * Note that the file's private data points back to this structure.
 */
struct hardwall_info {
        struct list_head list;             /* for hardwall_types.list */
        struct list_head task_head;        /* head of tasks in this hardwall */
        struct hardwall_type *type;        /* type of this resource */
        struct cpumask cpumask;            /* cpus reserved */
        int id;                            /* integer id for this hardwall */
        int teardown_in_progress;          /* are we tearing this one down? */

        /* Remaining fields only valid for user-network resources. */
        int ulhc_x;                        /* upper left hand corner x coord */
        int ulhc_y;                        /* upper left hand corner y coord */
        int width;                         /* rectangle width */
        int height;                        /* rectangle height */
#if CHIP_HAS_REV1_XDN()
        atomic_t xdn_pending_count;        /* cores in phase 1 of drain */
#endif
};


/* /proc/tile/hardwall */
static struct proc_dir_entry *hardwall_proc_dir;

/* Functions to manage files in /proc/tile/hardwall. */
static void hardwall_add_proc(struct hardwall_info *);
static void hardwall_remove_proc(struct hardwall_info *);

/* Allow disabling UDN access. */
static int __init noudn(char *str)
{
        pr_info("User-space UDN access is disabled\n");
        hardwall_types[HARDWALL_UDN].disabled = 1;
        return 0;
}
early_param("noudn", noudn);

#ifndef __tilepro__
/* Allow disabling IDN access. */
static int __init noidn(char *str)
{
        pr_info("User-space IDN access is disabled\n");
        hardwall_types[HARDWALL_IDN].disabled = 1;
        return 0;
}
early_param("noidn", noidn);

/* Allow disabling IPI access. */
static int __init noipi(char *str)
{
        pr_info("User-space IPI access is disabled\n");
        hardwall_types[HARDWALL_IPI].disabled = 1;
        return 0;
}
early_param("noipi", noipi);
#endif


/*
 * Low-level primitives for UDN/IDN
 */

#ifdef __tilepro__
#define mtspr_XDN(hwt, name, val) \
        do { (void)(hwt); __insn_mtspr(SPR_UDN_##name, (val)); } while (0)
#define mtspr_MPL_XDN(hwt, name, val) \
        do { (void)(hwt); __insn_mtspr(SPR_MPL_UDN_##name, (val)); } while (0)
#define mfspr_XDN(hwt, name) \
        ((void)(hwt), __insn_mfspr(SPR_UDN_##name))
#else
#define mtspr_XDN(hwt, name, val)                                       \
        do {                                                            \
                if ((hwt)->is_idn)                                      \
                        __insn_mtspr(SPR_IDN_##name, (val));            \
                else                                                    \
                        __insn_mtspr(SPR_UDN_##name, (val));            \
        } while (0)
#define mtspr_MPL_XDN(hwt, name, val)                                   \
        do {                                                            \
                if ((hwt)->is_idn)                                      \
                        __insn_mtspr(SPR_MPL_IDN_##name, (val));        \
                else                                                    \
                        __insn_mtspr(SPR_MPL_UDN_##name, (val));        \
        } while (0)
#define mfspr_XDN(hwt, name) \
  ((hwt)->is_idn ? __insn_mfspr(SPR_IDN_##name) : __insn_mfspr(SPR_UDN_##name))
#endif

/* Set a CPU bit if the CPU is online. */
#define cpu_online_set(cpu, dst) do { \
        if (cpu_online(cpu))          \
                cpumask_set_cpu(cpu, dst);    \
} while (0)


/* Does the given rectangle contain the given x,y coordinate? */
static int contains(struct hardwall_info *r, int x, int y)
{
        return (x >= r->ulhc_x && x < r->ulhc_x + r->width) &&
                (y >= r->ulhc_y && y < r->ulhc_y + r->height);
}

/* Compute the rectangle parameters and validate the cpumask. */
static int check_rectangle(struct hardwall_info *r, struct cpumask *mask)
{
        int x, y, cpu, ulhc, lrhc;

        /* The first cpu is the ULHC, the last the LRHC. */
        ulhc = find_first_bit(cpumask_bits(mask), nr_cpumask_bits);
        lrhc = find_last_bit(cpumask_bits(mask), nr_cpumask_bits);

        /* Compute the rectangle attributes from the cpus. */
        r->ulhc_x = cpu_x(ulhc);
        r->ulhc_y = cpu_y(ulhc);
        r->width = cpu_x(lrhc) - r->ulhc_x + 1;
        r->height = cpu_y(lrhc) - r->ulhc_y + 1;

        /* Width and height must be positive */
        if (r->width <= 0 || r->height <= 0)
                return -EINVAL;

        /* Confirm that the cpumask is exactly the rectangle. */
        for (y = 0, cpu = 0; y < smp_height; ++y)
                for (x = 0; x < smp_width; ++x, ++cpu)
                        if (cpumask_test_cpu(cpu, mask) != contains(r, x, y))
                                return -EINVAL;

        /*
         * Note that offline cpus can't be drained when this user network
         * rectangle eventually closes.  We used to detect this
         * situation and print a warning, but it annoyed users and
         * they ignored it anyway, so now we just return without a
         * warning.
         */
        return 0;
}

/*
 * Hardware management of hardwall setup, teardown, trapping,
 * and enabling/disabling PL0 access to the networks.
 */

/* Bit field values to mask together for writes to SPR_XDN_DIRECTION_PROTECT */
enum direction_protect {
        N_PROTECT = (1 << 0),
        E_PROTECT = (1 << 1),
        S_PROTECT = (1 << 2),
        W_PROTECT = (1 << 3),
        C_PROTECT = (1 << 4),
};

static inline int xdn_which_interrupt(struct hardwall_type *hwt)
{
#ifndef __tilepro__
        if (hwt->is_idn)
                return INT_IDN_FIREWALL;
#endif
        return INT_UDN_FIREWALL;
}

static void enable_firewall_interrupts(struct hardwall_type *hwt)
{
        arch_local_irq_unmask_now(xdn_which_interrupt(hwt));
}

static void disable_firewall_interrupts(struct hardwall_type *hwt)
{
        arch_local_irq_mask_now(xdn_which_interrupt(hwt));
}

/* Set up hardwall on this cpu based on the passed hardwall_info. */
static void hardwall_setup_func(void *info)
{
        struct hardwall_info *r = info;
        struct hardwall_type *hwt = r->type;

        int cpu = smp_processor_id();  /* on_each_cpu disables preemption */
        int x = cpu_x(cpu);
        int y = cpu_y(cpu);
        int bits = 0;
        if (x == r->ulhc_x)
                bits |= W_PROTECT;
        if (x == r->ulhc_x + r->width - 1)
                bits |= E_PROTECT;
        if (y == r->ulhc_y)
                bits |= N_PROTECT;
        if (y == r->ulhc_y + r->height - 1)
                bits |= S_PROTECT;
        BUG_ON(bits == 0);
        mtspr_XDN(hwt, DIRECTION_PROTECT, bits);
        enable_firewall_interrupts(hwt);
}

/* Set up all cpus on edge of rectangle to enable/disable hardwall SPRs. */
static void hardwall_protect_rectangle(struct hardwall_info *r)
{
        int x, y, cpu, delta;
        struct cpumask rect_cpus;

        cpumask_clear(&rect_cpus);

        /* First include the top and bottom edges */
        cpu = r->ulhc_y * smp_width + r->ulhc_x;
        delta = (r->height - 1) * smp_width;
        for (x = 0; x < r->width; ++x, ++cpu) {
                cpu_online_set(cpu, &rect_cpus);
                cpu_online_set(cpu + delta, &rect_cpus);
        }

        /* Then the left and right edges */
        cpu -= r->width;
        delta = r->width - 1;
        for (y = 0; y < r->height; ++y, cpu += smp_width) {
                cpu_online_set(cpu, &rect_cpus);
                cpu_online_set(cpu + delta, &rect_cpus);
        }

        /* Then tell all the cpus to set up their protection SPR */
        on_each_cpu_mask(&rect_cpus, hardwall_setup_func, r, 1);
}

/* Entered from INT_xDN_FIREWALL interrupt vector with irqs disabled. */
void __kprobes do_hardwall_trap(struct pt_regs* regs, int fault_num)
{
        struct hardwall_info *rect;
        struct hardwall_type *hwt;
        struct task_struct *p;
        struct siginfo info;
        int cpu = smp_processor_id();
        int found_processes;
        struct pt_regs *old_regs = set_irq_regs(regs);

        irq_enter();

        /* Figure out which network trapped. */
        switch (fault_num) {
#ifndef __tilepro__
        case INT_IDN_FIREWALL:
                hwt = &hardwall_types[HARDWALL_IDN];
                break;
#endif
        case INT_UDN_FIREWALL:
                hwt = &hardwall_types[HARDWALL_UDN];
                break;
        default:
                BUG();
        }
        BUG_ON(hwt->disabled);

        /* This tile trapped a network access; find the rectangle. */
        spin_lock(&hwt->lock);
        list_for_each_entry(rect, &hwt->list, list) {
                if (cpumask_test_cpu(cpu, &rect->cpumask))
                        break;
        }

        /*
         * It shouldn't be possible not to find this cpu on the
         * rectangle list, since only cpus in rectangles get hardwalled.
         * The hardwall is only removed after the user network is drained.
         */
        BUG_ON(&rect->list == &hwt->list);

        /*
         * If we already started teardown on this hardwall, don't worry;
         * the abort signal has been sent and we are just waiting for things
         * to quiesce.
         */
        if (rect->teardown_in_progress) {
                pr_notice("cpu %d: detected %s hardwall violation %#lx while teardown already in progress\n",
                          cpu, hwt->name,
                          (long)mfspr_XDN(hwt, DIRECTION_PROTECT));
                goto done;
        }

        /*
         * Kill off any process that is activated in this rectangle.
         * We bypass security to deliver the signal, since it must be
         * one of the activated processes that generated the user network
         * message that caused this trap, and all the activated
         * processes shared a single open file so are pretty tightly
         * bound together from a security point of view to begin with.
         */
        rect->teardown_in_progress = 1;
        wmb(); /* Ensure visibility of rectangle before notifying processes. */
        pr_notice("cpu %d: detected %s hardwall violation %#lx...\n",
                  cpu, hwt->name, (long)mfspr_XDN(hwt, DIRECTION_PROTECT));
        info.si_signo = SIGILL;
        info.si_errno = 0;
        info.si_code = ILL_HARDWALL;
        found_processes = 0;
        list_for_each_entry(p, &rect->task_head,
                            thread.hardwall[hwt->index].list) {
                BUG_ON(p->thread.hardwall[hwt->index].info != rect);
                if (!(p->flags & PF_EXITING)) {
                        found_processes = 1;
                        pr_notice("hardwall: killing %d\n", p->pid);
                        do_send_sig_info(info.si_signo, &info, p, false);
                }
        }
        if (!found_processes)
                pr_notice("hardwall: no associated processes!\n");

 done:
        spin_unlock(&hwt->lock);

        /*
         * We have to disable firewall interrupts now, or else when we
         * return from this handler, we will simply re-interrupt back to
         * it.  However, we can't clear the protection bits, since we
         * haven't yet drained the network, and that would allow packets
         * to cross out of the hardwall region.
         */
        disable_firewall_interrupts(hwt);

        irq_exit();
        set_irq_regs(old_regs);
}

/* Allow access from user space to the user network. */
void grant_hardwall_mpls(struct hardwall_type *hwt)
{
#ifndef __tilepro__
        if (!hwt->is_xdn) {
                __insn_mtspr(SPR_MPL_IPI_0_SET_0, 1);
                return;
        }
#endif
        mtspr_MPL_XDN(hwt, ACCESS_SET_0, 1);
        mtspr_MPL_XDN(hwt, AVAIL_SET_0, 1);
        mtspr_MPL_XDN(hwt, COMPLETE_SET_0, 1);
        mtspr_MPL_XDN(hwt, TIMER_SET_0, 1);
#if !CHIP_HAS_REV1_XDN()
        mtspr_MPL_XDN(hwt, REFILL_SET_0, 1);
        mtspr_MPL_XDN(hwt, CA_SET_0, 1);
#endif
}

/* Deny access from user space to the user network. */
void restrict_hardwall_mpls(struct hardwall_type *hwt)
{
#ifndef __tilepro__
        if (!hwt->is_xdn) {
                __insn_mtspr(SPR_MPL_IPI_0_SET_1, 1);
                return;
        }
#endif
        mtspr_MPL_XDN(hwt, ACCESS_SET_1, 1);
        mtspr_MPL_XDN(hwt, AVAIL_SET_1, 1);
        mtspr_MPL_XDN(hwt, COMPLETE_SET_1, 1);
        mtspr_MPL_XDN(hwt, TIMER_SET_1, 1);
#if !CHIP_HAS_REV1_XDN()
        mtspr_MPL_XDN(hwt, REFILL_SET_1, 1);
        mtspr_MPL_XDN(hwt, CA_SET_1, 1);
#endif
}

/* Restrict or deny as necessary for the task we're switching to. */
void hardwall_switch_tasks(struct task_struct *prev,
                           struct task_struct *next)
{
        int i;
        for (i = 0; i < HARDWALL_TYPES; ++i) {
                if (prev->thread.hardwall[i].info != NULL) {
                        if (next->thread.hardwall[i].info == NULL)
                                restrict_hardwall_mpls(&hardwall_types[i]);
                } else if (next->thread.hardwall[i].info != NULL) {
                        grant_hardwall_mpls(&hardwall_types[i]);
                }
        }
}

/* Does this task have the right to IPI the given cpu? */
int hardwall_ipi_valid(int cpu)
{
#ifdef __tilegx__
        struct hardwall_info *info =
                current->thread.hardwall[HARDWALL_IPI].info;
        return info && cpumask_test_cpu(cpu, &info->cpumask);
#else
        return 0;
#endif
}

/*
 * Code to create, activate, deactivate, and destroy hardwall resources.
 */

/* Create a hardwall for the given resource */
static struct hardwall_info *hardwall_create(struct hardwall_type *hwt,
                                             size_t size,
                                             const unsigned char __user *bits)
{
        struct hardwall_info *iter, *info;
        struct cpumask mask;
        unsigned long flags;
        int rc;

        /* Reject crazy sizes out of hand, a la sys_mbind(). */
        if (size > PAGE_SIZE)
                return ERR_PTR(-EINVAL);

        /* Copy whatever fits into a cpumask. */
        if (copy_from_user(&mask, bits, min(sizeof(struct cpumask), size)))
                return ERR_PTR(-EFAULT);

        /*
         * If the size was short, clear the rest of the mask;
         * otherwise validate that the rest of the user mask was zero
         * (we don't try hard to be efficient when validating huge masks).
         */
        if (size < sizeof(struct cpumask)) {
                memset((char *)&mask + size, 0, sizeof(struct cpumask) - size);
        } else if (size > sizeof(struct cpumask)) {
                size_t i;
                for (i = sizeof(struct cpumask); i < size; ++i) {
                        char c;
                        if (get_user(c, &bits[i]))
                                return ERR_PTR(-EFAULT);
                        if (c)
                                return ERR_PTR(-EINVAL);
                }
        }

        /* Allocate a new hardwall_info optimistically. */
        info = kmalloc(sizeof(struct hardwall_info),
                        GFP_KERNEL | __GFP_ZERO);
        if (info == NULL)
                return ERR_PTR(-ENOMEM);
        INIT_LIST_HEAD(&info->task_head);
        info->type = hwt;

        /* Compute the rectangle size and validate that it's plausible. */
        cpumask_copy(&info->cpumask, &mask);
        info->id = find_first_bit(cpumask_bits(&mask), nr_cpumask_bits);
        if (hwt->is_xdn) {
                rc = check_rectangle(info, &mask);
                if (rc != 0) {
                        kfree(info);
                        return ERR_PTR(rc);
                }
        }

        /*
         * Eliminate cpus that are not part of this Linux client.
         * Note that this allows for configurations that we might not want to
         * support, such as one client on every even cpu, another client on
         * every odd cpu.
         */
        cpumask_and(&info->cpumask, &info->cpumask, cpu_online_mask);

        /* Confirm it doesn't overlap and add it to the list. */
        spin_lock_irqsave(&hwt->lock, flags);
        list_for_each_entry(iter, &hwt->list, list) {
                if (cpumask_intersects(&iter->cpumask, &info->cpumask)) {
                        spin_unlock_irqrestore(&hwt->lock, flags);
                        kfree(info);
                        return ERR_PTR(-EBUSY);
                }
        }
        list_add_tail(&info->list, &hwt->list);
        spin_unlock_irqrestore(&hwt->lock, flags);

        /* Set up appropriate hardwalling on all affected cpus. */
        if (hwt->is_xdn)
                hardwall_protect_rectangle(info);

        /* Create a /proc/tile/hardwall entry. */
        hardwall_add_proc(info);

        return info;
}

/* Activate a given hardwall on this cpu for this process. */
static int hardwall_activate(struct hardwall_info *info)
{
        int cpu;
        unsigned long flags;
        struct task_struct *p = current;
        struct thread_struct *ts = &p->thread;
        struct hardwall_type *hwt;

        /* Require a hardwall. */
        if (info == NULL)
                return -ENODATA;

        /* Not allowed to activate a hardwall that is being torn down. */
        if (info->teardown_in_progress)
                return -EINVAL;

        /*
         * Get our affinity; if we're not bound to this tile uniquely,
         * we can't access the network registers.
         */
        if (cpumask_weight(&p->cpus_allowed) != 1)
                return -EPERM;

        /* Make sure we are bound to a cpu assigned to this resource. */
        cpu = smp_processor_id();
        BUG_ON(cpumask_first(&p->cpus_allowed) != cpu);
        if (!cpumask_test_cpu(cpu, &info->cpumask))
                return -EINVAL;

        /* If we are already bound to this hardwall, it's a no-op. */
        hwt = info->type;
        if (ts->hardwall[hwt->index].info) {
                BUG_ON(ts->hardwall[hwt->index].info != info);
                return 0;
        }

        /* Success!  This process gets to use the resource on this cpu. */
        ts->hardwall[hwt->index].info = info;
        spin_lock_irqsave(&hwt->lock, flags);
        list_add(&ts->hardwall[hwt->index].list, &info->task_head);
        spin_unlock_irqrestore(&hwt->lock, flags);
        grant_hardwall_mpls(hwt);
        printk(KERN_DEBUG "Pid %d (%s) activated for %s hardwall: cpu %d\n",
               p->pid, p->comm, hwt->name, cpu);
        return 0;
}

/*
 * Deactivate a task's hardwall.  Must hold lock for hardwall_type.
 * This method may be called from exit_thread(), so we don't want to
 * rely on too many fields of struct task_struct still being valid.
 * We assume the cpus_allowed, pid, and comm fields are still valid.
 */
static void _hardwall_deactivate(struct hardwall_type *hwt,
                                 struct task_struct *task)
{
        struct thread_struct *ts = &task->thread;

        if (cpumask_weight(&task->cpus_allowed) != 1) {
                pr_err("pid %d (%s) releasing %s hardwall with an affinity mask containing %d cpus!\n",
                       task->pid, task->comm, hwt->name,
                       cpumask_weight(&task->cpus_allowed));
                BUG();
        }

        BUG_ON(ts->hardwall[hwt->index].info == NULL);
        ts->hardwall[hwt->index].info = NULL;
        list_del(&ts->hardwall[hwt->index].list);
        if (task == current)
                restrict_hardwall_mpls(hwt);
}

/* Deactivate a task's hardwall. */
static int hardwall_deactivate(struct hardwall_type *hwt,
                               struct task_struct *task)
{
        unsigned long flags;
        int activated;

        spin_lock_irqsave(&hwt->lock, flags);
        activated = (task->thread.hardwall[hwt->index].info != NULL);
        if (activated)
                _hardwall_deactivate(hwt, task);
        spin_unlock_irqrestore(&hwt->lock, flags);

        if (!activated)
                return -EINVAL;

        printk(KERN_DEBUG "Pid %d (%s) deactivated for %s hardwall: cpu %d\n",
               task->pid, task->comm, hwt->name, raw_smp_processor_id());
        return 0;
}

void hardwall_deactivate_all(struct task_struct *task)
{
        int i;
        for (i = 0; i < HARDWALL_TYPES; ++i)
                if (task->thread.hardwall[i].info)
                        hardwall_deactivate(&hardwall_types[i], task);
}

/* Stop the switch before draining the network. */
static void stop_xdn_switch(void *arg)
{
#if !CHIP_HAS_REV1_XDN()
        /* Freeze the switch and the demux. */
        __insn_mtspr(SPR_UDN_SP_FREEZE,
                     SPR_UDN_SP_FREEZE__SP_FRZ_MASK |
                     SPR_UDN_SP_FREEZE__DEMUX_FRZ_MASK |
                     SPR_UDN_SP_FREEZE__NON_DEST_EXT_MASK);
#else
        /*
         * Drop all packets bound for the core or off the edge.
         * We rely on the normal hardwall protection setup code
         * to have set the low four bits to trigger firewall interrupts,
         * and shift those bits up to trigger "drop on send" semantics,
         * plus adding "drop on send to core" for all switches.
         * In practice it seems the switches latch the DIRECTION_PROTECT
         * SPR so they won't start dropping if they're already
         * delivering the last message to the core, but it doesn't
         * hurt to enable it here.
         */
        struct hardwall_type *hwt = arg;
        unsigned long protect = mfspr_XDN(hwt, DIRECTION_PROTECT);
        mtspr_XDN(hwt, DIRECTION_PROTECT, (protect | C_PROTECT) << 5);
#endif
}

static void empty_xdn_demuxes(struct hardwall_type *hwt)
{
#ifndef __tilepro__
        if (hwt->is_idn) {
                while (__insn_mfspr(SPR_IDN_DATA_AVAIL) & (1 << 0))
                        (void) __tile_idn0_receive();
                while (__insn_mfspr(SPR_IDN_DATA_AVAIL) & (1 << 1))
                        (void) __tile_idn1_receive();
                return;
        }
#endif
        while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 0))
                (void) __tile_udn0_receive();
        while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 1))
                (void) __tile_udn1_receive();
        while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 2))
                (void) __tile_udn2_receive();
        while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 3))
                (void) __tile_udn3_receive();
}

/* Drain all the state from a stopped switch. */
static void drain_xdn_switch(void *arg)
{
        struct hardwall_info *info = arg;
        struct hardwall_type *hwt = info->type;

#if CHIP_HAS_REV1_XDN()
        /*
         * The switches have been configured to drop any messages
         * destined for cores (or off the edge of the rectangle).
         * But the current message may continue to be delivered,
         * so we wait until all the cores have finished any pending
         * messages before we stop draining.
         */
        int pending = mfspr_XDN(hwt, PENDING);
        while (pending--) {
                empty_xdn_demuxes(hwt);
                if (hwt->is_idn)
                        __tile_idn_send(0);
                else
                        __tile_udn_send(0);
        }
        atomic_dec(&info->xdn_pending_count);
        while (atomic_read(&info->xdn_pending_count))
                empty_xdn_demuxes(hwt);
#else
        int i;
        int from_tile_words, ca_count;

        /* Empty out the 5 switch point fifos. */
        for (i = 0; i < 5; i++) {
                int words, j;
                __insn_mtspr(SPR_UDN_SP_FIFO_SEL, i);
                words = __insn_mfspr(SPR_UDN_SP_STATE) & 0xF;
                for (j = 0; j < words; j++)
                        (void) __insn_mfspr(SPR_UDN_SP_FIFO_DATA);
                BUG_ON((__insn_mfspr(SPR_UDN_SP_STATE) & 0xF) != 0);
        }

        /* Dump out the 3 word fifo at top. */
        from_tile_words = (__insn_mfspr(SPR_UDN_DEMUX_STATUS) >> 10) & 0x3;
        for (i = 0; i < from_tile_words; i++)
                (void) __insn_mfspr(SPR_UDN_DEMUX_WRITE_FIFO);

        /* Empty out demuxes. */
        empty_xdn_demuxes(hwt);

        /* Empty out catch all. */
        ca_count = __insn_mfspr(SPR_UDN_DEMUX_CA_COUNT);
        for (i = 0; i < ca_count; i++)
                (void) __insn_mfspr(SPR_UDN_CA_DATA);
        BUG_ON(__insn_mfspr(SPR_UDN_DEMUX_CA_COUNT) != 0);

        /* Clear demux logic. */
        __insn_mtspr(SPR_UDN_DEMUX_CTL, 1);

        /*
         * Write switch state; experimentation indicates that 0xc3000
         * is an idle switch point.
         */
        for (i = 0; i < 5; i++) {
                __insn_mtspr(SPR_UDN_SP_FIFO_SEL, i);
                __insn_mtspr(SPR_UDN_SP_STATE, 0xc3000);
        }
#endif
}

/* Reset random XDN state registers at boot up and during hardwall teardown. */
static void reset_xdn_network_state(struct hardwall_type *hwt)
{
        if (hwt->disabled)
                return;

        /* Clear out other random registers so we have a clean slate. */
        mtspr_XDN(hwt, DIRECTION_PROTECT, 0);
        mtspr_XDN(hwt, AVAIL_EN, 0);
        mtspr_XDN(hwt, DEADLOCK_TIMEOUT, 0);

#if !CHIP_HAS_REV1_XDN()
        /* Reset UDN coordinates to their standard value */
        {
                unsigned int cpu = smp_processor_id();
                unsigned int x = cpu_x(cpu);
                unsigned int y = cpu_y(cpu);
                __insn_mtspr(SPR_UDN_TILE_COORD, (x << 18) | (y << 7));
        }

        /* Set demux tags to predefined values and enable them. */
        __insn_mtspr(SPR_UDN_TAG_VALID, 0xf);
        __insn_mtspr(SPR_UDN_TAG_0, (1 << 0));
        __insn_mtspr(SPR_UDN_TAG_1, (1 << 1));
        __insn_mtspr(SPR_UDN_TAG_2, (1 << 2));
        __insn_mtspr(SPR_UDN_TAG_3, (1 << 3));

        /* Set other rev0 random registers to a clean state. */
        __insn_mtspr(SPR_UDN_REFILL_EN, 0);
        __insn_mtspr(SPR_UDN_DEMUX_QUEUE_SEL, 0);
        __insn_mtspr(SPR_UDN_SP_FIFO_SEL, 0);

        /* Start the switch and demux. */
        __insn_mtspr(SPR_UDN_SP_FREEZE, 0);
#endif
}

void reset_network_state(void)
{
        reset_xdn_network_state(&hardwall_types[HARDWALL_UDN]);
#ifndef __tilepro__
        reset_xdn_network_state(&hardwall_types[HARDWALL_IDN]);
#endif
}

/* Restart an XDN switch after draining. */
static void restart_xdn_switch(void *arg)
{
        struct hardwall_type *hwt = arg;

#if CHIP_HAS_REV1_XDN()
        /* One last drain step to avoid races with injection and draining. */
        empty_xdn_demuxes(hwt);
#endif

        reset_xdn_network_state(hwt);

        /* Disable firewall interrupts. */
        disable_firewall_interrupts(hwt);
}

/* Last reference to a hardwall is gone, so clear the network. */
static void hardwall_destroy(struct hardwall_info *info)
{
        struct task_struct *task;
        struct hardwall_type *hwt;
        unsigned long flags;

        /* Make sure this file actually represents a hardwall. */
        if (info == NULL)
                return;

        /*
         * Deactivate any remaining tasks.  It's possible to race with
         * some other thread that is exiting and hasn't yet called
         * deactivate (when freeing its thread_info), so we carefully
         * deactivate any remaining tasks before freeing the
         * hardwall_info object itself.
         */
        hwt = info->type;
        info->teardown_in_progress = 1;
        spin_lock_irqsave(&hwt->lock, flags);
        list_for_each_entry(task, &info->task_head,
                            thread.hardwall[hwt->index].list)
                _hardwall_deactivate(hwt, task);
        spin_unlock_irqrestore(&hwt->lock, flags);

        if (hwt->is_xdn) {
                /* Configure the switches for draining the user network. */
                printk(KERN_DEBUG
                       "Clearing %s hardwall rectangle %dx%d %d,%d\n",
                       hwt->name, info->width, info->height,
                       info->ulhc_x, info->ulhc_y);
                on_each_cpu_mask(&info->cpumask, stop_xdn_switch, hwt, 1);

                /* Drain the network. */
#if CHIP_HAS_REV1_XDN()
                atomic_set(&info->xdn_pending_count,
                           cpumask_weight(&info->cpumask));
                on_each_cpu_mask(&info->cpumask, drain_xdn_switch, info, 0);
#else
                on_each_cpu_mask(&info->cpumask, drain_xdn_switch, info, 1);
#endif

                /* Restart switch and disable firewall. */
                on_each_cpu_mask(&info->cpumask, restart_xdn_switch, hwt, 1);
        }

        /* Remove the /proc/tile/hardwall entry. */
        hardwall_remove_proc(info);

        /* Now free the hardwall from the list. */
        spin_lock_irqsave(&hwt->lock, flags);
        BUG_ON(!list_empty(&info->task_head));
        list_del(&info->list);
        spin_unlock_irqrestore(&hwt->lock, flags);
        kfree(info);
}


static int hardwall_proc_show(struct seq_file *sf, void *v)
{
        struct hardwall_info *info = sf->private;

        seq_printf(sf, "%*pbl\n", cpumask_pr_args(&info->cpumask));
        return 0;
}

static int hardwall_proc_open(struct inode *inode,
                              struct file *file)
{
        return single_open(file, hardwall_proc_show, PDE_DATA(inode));
}

static const struct file_operations hardwall_proc_fops = {
        .open           = hardwall_proc_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void hardwall_add_proc(struct hardwall_info *info)
{
        char buf[64];
        snprintf(buf, sizeof(buf), "%d", info->id);
        proc_create_data(buf, 0444, info->type->proc_dir,
                         &hardwall_proc_fops, info);
}

static void hardwall_remove_proc(struct hardwall_info *info)
{
        char buf[64];
        snprintf(buf, sizeof(buf), "%d", info->id);
        remove_proc_entry(buf, info->type->proc_dir);
}

int proc_pid_hardwall(struct seq_file *m, struct pid_namespace *ns,
                      struct pid *pid, struct task_struct *task)
{
        int i;
        int n = 0;
        for (i = 0; i < HARDWALL_TYPES; ++i) {
                struct hardwall_info *info = task->thread.hardwall[i].info;
                if (info)
                        seq_printf(m, "%s: %d\n", info->type->name, info->id);
        }
        return n;
}

void proc_tile_hardwall_init(struct proc_dir_entry *root)
{
        int i;
        for (i = 0; i < HARDWALL_TYPES; ++i) {
                struct hardwall_type *hwt = &hardwall_types[i];
                if (hwt->disabled)
                        continue;
                if (hardwall_proc_dir == NULL)
                        hardwall_proc_dir = proc_mkdir("hardwall", root);
                hwt->proc_dir = proc_mkdir(hwt->name, hardwall_proc_dir);
        }
}


/*
 * Character device support via ioctl/close.
 */

static long hardwall_ioctl(struct file *file, unsigned int a, unsigned long b)
{
        struct hardwall_info *info = file->private_data;
        int minor = iminor(file->f_mapping->host);
        struct hardwall_type* hwt;

        if (_IOC_TYPE(a) != HARDWALL_IOCTL_BASE)
                return -EINVAL;

        BUILD_BUG_ON(HARDWALL_TYPES != _HARDWALL_TYPES);
        BUILD_BUG_ON(HARDWALL_TYPES !=
                     sizeof(hardwall_types)/sizeof(hardwall_types[0]));

        if (minor < 0 || minor >= HARDWALL_TYPES)
                return -EINVAL;
        hwt = &hardwall_types[minor];
        WARN_ON(info && hwt != info->type);

        switch (_IOC_NR(a)) {
        case _HARDWALL_CREATE:
                if (hwt->disabled)
                        return -ENOSYS;
                if (info != NULL)
                        return -EALREADY;
                info = hardwall_create(hwt, _IOC_SIZE(a),
                                       (const unsigned char __user *)b);
                if (IS_ERR(info))
                        return PTR_ERR(info);
                file->private_data = info;
                return 0;

        case _HARDWALL_ACTIVATE:
                return hardwall_activate(info);

        case _HARDWALL_DEACTIVATE:
                if (current->thread.hardwall[hwt->index].info != info)
                        return -EINVAL;
                return hardwall_deactivate(hwt, current);

        case _HARDWALL_GET_ID:
                return info ? info->id : -EINVAL;

        default:
                return -EINVAL;
        }
}

#ifdef CONFIG_COMPAT
static long hardwall_compat_ioctl(struct file *file,
                                  unsigned int a, unsigned long b)
{
        /* Sign-extend the argument so it can be used as a pointer. */
        return hardwall_ioctl(file, a, (unsigned long)compat_ptr(b));
}
#endif

/* The user process closed the file; revoke access to user networks. */
static int hardwall_flush(struct file *file, fl_owner_t owner)
{
        struct hardwall_info *info = file->private_data;
        struct task_struct *task, *tmp;
        unsigned long flags;

        if (info) {
                /*
                 * NOTE: if multiple threads are activated on this hardwall
                 * file, the other threads will continue having access to the
                 * user network until they are context-switched out and back
                 * in again.
                 *
                 * NOTE: A NULL files pointer means the task is being torn
                 * down, so in that case we also deactivate it.
                 */
                struct hardwall_type *hwt = info->type;
                spin_lock_irqsave(&hwt->lock, flags);
                list_for_each_entry_safe(task, tmp, &info->task_head,
                                         thread.hardwall[hwt->index].list) {
                        if (task->files == owner || task->files == NULL)
                                _hardwall_deactivate(hwt, task);
                }
                spin_unlock_irqrestore(&hwt->lock, flags);
        }

        return 0;
}

/* This hardwall is gone, so destroy it. */
static int hardwall_release(struct inode *inode, struct file *file)
{
        hardwall_destroy(file->private_data);
        return 0;
}

static const struct file_operations dev_hardwall_fops = {
        .open           = nonseekable_open,
        .unlocked_ioctl = hardwall_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = hardwall_compat_ioctl,
#endif
        .flush          = hardwall_flush,
        .release        = hardwall_release,
};

static struct cdev hardwall_dev;

static int __init dev_hardwall_init(void)
{
        int rc;
        dev_t dev;

        rc = alloc_chrdev_region(&dev, 0, HARDWALL_TYPES, "hardwall");
        if (rc < 0)
                return rc;
        cdev_init(&hardwall_dev, &dev_hardwall_fops);
        rc = cdev_add(&hardwall_dev, dev, HARDWALL_TYPES);
        if (rc < 0)
                return rc;

        return 0;
}
late_initcall(dev_hardwall_init);