/*
 * Copyright 2014 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include <linux/mm_types.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/sched/signal.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/memory.h>
#include "kfd_priv.h"
#include "kfd_events.h"
#include <linux/device.h>

/*
 * A task can only be on a single wait_queue at a time, but we need to support
 * waiting on multiple events (any/all).
 * Instead of each event simply having a wait_queue with sleeping tasks, it
 * has a singly-linked list of tasks.
 * A thread that wants to sleep creates an array of these, one for each event
 * and adds one to each event's waiter chain.
 */
struct kfd_event_waiter {
        struct list_head waiters;
        struct task_struct *sleeping_task;

        /* Transitions to true when the event this belongs to is signaled. */
        bool activated;

        /* Event */
        struct kfd_event *event;
        uint32_t input_index;
};

/*
 * Over-complicated pooled allocator for event notification slots.
 *
 * Each signal event needs a 64-bit signal slot where the signaler will write
 * a 1 before sending an interrupt.l (This is needed because some interrupts
 * do not contain enough spare data bits to identify an event.)
 * We get whole pages from vmalloc and map them to the process VA.
 * Individual signal events are then allocated a slot in a page.
 */

struct signal_page {
        struct list_head event_pages;   /* kfd_process.signal_event_pages */
        uint64_t *kernel_address;
        uint64_t __user *user_address;
        uint32_t page_index;            /* Index into the mmap aperture. */
        unsigned int free_slots;
        unsigned long used_slot_bitmap[0];
};

#define SLOTS_PER_PAGE KFD_SIGNAL_EVENT_LIMIT
#define SLOT_BITMAP_SIZE BITS_TO_LONGS(SLOTS_PER_PAGE)
#define BITS_PER_PAGE (ilog2(SLOTS_PER_PAGE)+1)
#define SIGNAL_PAGE_SIZE (sizeof(struct signal_page) + \
                                SLOT_BITMAP_SIZE * sizeof(long))

/*
 * For signal events, the event ID is used as the interrupt user data.
 * For SQ s_sendmsg interrupts, this is limited to 8 bits.
 */

#define INTERRUPT_DATA_BITS 8
#define SIGNAL_EVENT_ID_SLOT_SHIFT 0

static uint64_t *page_slots(struct signal_page *page)
{
        return page->kernel_address;
}

static bool allocate_free_slot(struct kfd_process *process,
                                struct signal_page **out_page,
                                unsigned int *out_slot_index)
{
        struct signal_page *page;

        list_for_each_entry(page, &process->signal_event_pages, event_pages) {
                if (page->free_slots > 0) {
                        unsigned int slot =
                                find_first_zero_bit(page->used_slot_bitmap,
                                                        SLOTS_PER_PAGE);

                        __set_bit(slot, page->used_slot_bitmap);
                        page->free_slots--;

                        page_slots(page)[slot] = UNSIGNALED_EVENT_SLOT;

                        *out_page = page;
                        *out_slot_index = slot;

                        pr_debug("allocated event signal slot in page %p, slot %d\n",
                                        page, slot);

                        return true;
                }
        }

        pr_debug("No free event signal slots were found for process %p\n",
                        process);

        return false;
}

#define list_tail_entry(head, type, member) \
        list_entry((head)->prev, type, member)

static bool allocate_signal_page(struct file *devkfd, struct kfd_process *p)
{
        void *backing_store;
        struct signal_page *page;

        page = kzalloc(SIGNAL_PAGE_SIZE, GFP_KERNEL);
        if (!page)
                goto fail_alloc_signal_page;

        page->free_slots = SLOTS_PER_PAGE;

        backing_store = (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                        get_order(KFD_SIGNAL_EVENT_LIMIT * 8));
        if (!backing_store)
                goto fail_alloc_signal_store;

        /* prevent user-mode info leaks */
        memset(backing_store, (uint8_t) UNSIGNALED_EVENT_SLOT,
                KFD_SIGNAL_EVENT_LIMIT * 8);

        page->kernel_address = backing_store;

        if (list_empty(&p->signal_event_pages))
                page->page_index = 0;
        else
                page->page_index = list_tail_entry(&p->signal_event_pages,
                                                   struct signal_page,
                                                   event_pages)->page_index + 1;

        pr_debug("allocated new event signal page at %p, for process %p\n",
                        page, p);
        pr_debug("page index is %d\n", page->page_index);

        list_add(&page->event_pages, &p->signal_event_pages);

        return true;

fail_alloc_signal_store:
        kfree(page);
fail_alloc_signal_page:
        return false;
}

static bool allocate_event_notification_slot(struct file *devkfd,
                                        struct kfd_process *p,
                                        struct signal_page **page,
                                        unsigned int *signal_slot_index)
{
        bool ret;

        ret = allocate_free_slot(p, page, signal_slot_index);
        if (!ret) {
                ret = allocate_signal_page(devkfd, p);
                if (ret)
                        ret = allocate_free_slot(p, page, signal_slot_index);
        }

        return ret;
}

/* Assumes that the process's event_mutex is locked. */
static void release_event_notification_slot(struct signal_page *page,
                                                size_t slot_index)
{
        __clear_bit(slot_index, page->used_slot_bitmap);
        page->free_slots++;

        /* We don't free signal pages, they are retained by the process
         * and reused until it exits. */
}

static struct signal_page *lookup_signal_page_by_index(struct kfd_process *p,
                                                unsigned int page_index)
{
        struct signal_page *page;

        /*
         * This is safe because we don't delete signal pages until the
         * process exits.
         */
        list_for_each_entry(page, &p->signal_event_pages, event_pages)
                if (page->page_index == page_index)
                        return page;

        return NULL;
}

/*
 * Assumes that p->event_mutex is held and of course that p is not going
 * away (current or locked).
 */
static struct kfd_event *lookup_event_by_id(struct kfd_process *p, uint32_t id)
{
        struct kfd_event *ev;

        hash_for_each_possible(p->events, ev, events, id)
                if (ev->event_id == id)
                        return ev;

        return NULL;
}

static u32 make_signal_event_id(struct signal_page *page,
                                         unsigned int signal_slot_index)
{
        return page->page_index |
                        (signal_slot_index << SIGNAL_EVENT_ID_SLOT_SHIFT);
}

/*
 * Produce a kfd event id for a nonsignal event.
 * These are arbitrary numbers, so we do a sequential search through
 * the hash table for an unused number.
 */
static u32 make_nonsignal_event_id(struct kfd_process *p)
{
        u32 id;

        for (id = p->next_nonsignal_event_id;
                id < KFD_LAST_NONSIGNAL_EVENT_ID &&
                lookup_event_by_id(p, id) != NULL;
                id++)
                ;

        if (id < KFD_LAST_NONSIGNAL_EVENT_ID) {

                /*
                 * What if id == LAST_NONSIGNAL_EVENT_ID - 1?
                 * Then next_nonsignal_event_id = LAST_NONSIGNAL_EVENT_ID so
                 * the first loop fails immediately and we proceed with the
                 * wraparound loop below.
                 */
                p->next_nonsignal_event_id = id + 1;

                return id;
        }

        for (id = KFD_FIRST_NONSIGNAL_EVENT_ID;
                id < KFD_LAST_NONSIGNAL_EVENT_ID &&
                lookup_event_by_id(p, id) != NULL;
                id++)
                ;


        if (id < KFD_LAST_NONSIGNAL_EVENT_ID) {
                p->next_nonsignal_event_id = id + 1;
                return id;
        }

        p->next_nonsignal_event_id = KFD_FIRST_NONSIGNAL_EVENT_ID;
        return 0;
}

static struct kfd_event *lookup_event_by_page_slot(struct kfd_process *p,
                                                struct signal_page *page,
                                                unsigned int signal_slot)
{
        return lookup_event_by_id(p, make_signal_event_id(page, signal_slot));
}

static int create_signal_event(struct file *devkfd,
                                struct kfd_process *p,
                                struct kfd_event *ev)
{
        if (p->signal_event_count == KFD_SIGNAL_EVENT_LIMIT) {
                pr_warn("amdkfd: Signal event wasn't created because limit was reached\n");
                return -ENOMEM;
        }

        if (!allocate_event_notification_slot(devkfd, p, &ev->signal_page,
                                                &ev->signal_slot_index)) {
                pr_warn("amdkfd: Signal event wasn't created because out of kernel memory\n");
                return -ENOMEM;
        }

        p->signal_event_count++;

        ev->user_signal_address =
                        &ev->signal_page->user_address[ev->signal_slot_index];

        ev->event_id = make_signal_event_id(ev->signal_page,
                                                ev->signal_slot_index);

        pr_debug("signal event number %zu created with id %d, address %p\n",
                        p->signal_event_count, ev->event_id,
                        ev->user_signal_address);

        pr_debug("signal event number %zu created with id %d, address %p\n",
                        p->signal_event_count, ev->event_id,
                        ev->user_signal_address);

        return 0;
}

/*
 * No non-signal events are supported yet.
 * We create them as events that never signal.
 * Set event calls from user-mode are failed.
 */
static int create_other_event(struct kfd_process *p, struct kfd_event *ev)
{
        ev->event_id = make_nonsignal_event_id(p);
        if (ev->event_id == 0)
                return -ENOMEM;

        return 0;
}

void kfd_event_init_process(struct kfd_process *p)
{
        mutex_init(&p->event_mutex);
        hash_init(p->events);
        INIT_LIST_HEAD(&p->signal_event_pages);
        p->next_nonsignal_event_id = KFD_FIRST_NONSIGNAL_EVENT_ID;
        p->signal_event_count = 0;
}

static void destroy_event(struct kfd_process *p, struct kfd_event *ev)
{
        if (ev->signal_page != NULL) {
                release_event_notification_slot(ev->signal_page,
                                                ev->signal_slot_index);
                p->signal_event_count--;
        }

        /*
         * Abandon the list of waiters. Individual waiting threads will
         * clean up their own data.
         */
        list_del(&ev->waiters);

        hash_del(&ev->events);
        kfree(ev);
}

static void destroy_events(struct kfd_process *p)
{
        struct kfd_event *ev;
        struct hlist_node *tmp;
        unsigned int hash_bkt;

        hash_for_each_safe(p->events, hash_bkt, tmp, ev, events)
                destroy_event(p, ev);
}

/*
 * We assume that the process is being destroyed and there is no need to
 * unmap the pages or keep bookkeeping data in order.
 */
static void shutdown_signal_pages(struct kfd_process *p)
{
        struct signal_page *page, *tmp;

        list_for_each_entry_safe(page, tmp, &p->signal_event_pages,
                                        event_pages) {
                free_pages((unsigned long)page->kernel_address,
                                get_order(KFD_SIGNAL_EVENT_LIMIT * 8));
                kfree(page);
        }
}

void kfd_event_free_process(struct kfd_process *p)
{
        destroy_events(p);
        shutdown_signal_pages(p);
}

static bool event_can_be_gpu_signaled(const struct kfd_event *ev)
{
        return ev->type == KFD_EVENT_TYPE_SIGNAL ||
                                        ev->type == KFD_EVENT_TYPE_DEBUG;
}

static bool event_can_be_cpu_signaled(const struct kfd_event *ev)
{
        return ev->type == KFD_EVENT_TYPE_SIGNAL;
}

int kfd_event_create(struct file *devkfd, struct kfd_process *p,
                     uint32_t event_type, bool auto_reset, uint32_t node_id,
                     uint32_t *event_id, uint32_t *event_trigger_data,
                     uint64_t *event_page_offset, uint32_t *event_slot_index)
{
        int ret = 0;
        struct kfd_event *ev = kzalloc(sizeof(*ev), GFP_KERNEL);

        if (!ev)
                return -ENOMEM;

        ev->type = event_type;
        ev->auto_reset = auto_reset;
        ev->signaled = false;

        INIT_LIST_HEAD(&ev->waiters);

        *event_page_offset = 0;

        mutex_lock(&p->event_mutex);

        switch (event_type) {
        case KFD_EVENT_TYPE_SIGNAL:
        case KFD_EVENT_TYPE_DEBUG:
                ret = create_signal_event(devkfd, p, ev);
                if (!ret) {
                        *event_page_offset = (ev->signal_page->page_index |
                                        KFD_MMAP_EVENTS_MASK);
                        *event_page_offset <<= PAGE_SHIFT;
                        *event_slot_index = ev->signal_slot_index;
                }
                break;
        default:
                ret = create_other_event(p, ev);
                break;
        }

        if (!ret) {
                hash_add(p->events, &ev->events, ev->event_id);

                *event_id = ev->event_id;
                *event_trigger_data = ev->event_id;
        } else {
                kfree(ev);
        }

        mutex_unlock(&p->event_mutex);

        return ret;
}

/* Assumes that p is current. */
int kfd_event_destroy(struct kfd_process *p, uint32_t event_id)
{
        struct kfd_event *ev;
        int ret = 0;

        mutex_lock(&p->event_mutex);

        ev = lookup_event_by_id(p, event_id);

        if (ev)
                destroy_event(p, ev);
        else
                ret = -EINVAL;

        mutex_unlock(&p->event_mutex);
        return ret;
}

static void set_event(struct kfd_event *ev)
{
        struct kfd_event_waiter *waiter;
        struct kfd_event_waiter *next;

        /* Auto reset if the list is non-empty and we're waking someone. */
        ev->signaled = !ev->auto_reset || list_empty(&ev->waiters);

        list_for_each_entry_safe(waiter, next, &ev->waiters, waiters) {
                waiter->activated = true;

                /* _init because free_waiters will call list_del */
                list_del_init(&waiter->waiters);

                wake_up_process(waiter->sleeping_task);
        }
}

/* Assumes that p is current. */
int kfd_set_event(struct kfd_process *p, uint32_t event_id)
{
        int ret = 0;
        struct kfd_event *ev;

        mutex_lock(&p->event_mutex);

        ev = lookup_event_by_id(p, event_id);

        if (ev && event_can_be_cpu_signaled(ev))
                set_event(ev);
        else
                ret = -EINVAL;

        mutex_unlock(&p->event_mutex);
        return ret;
}

static void reset_event(struct kfd_event *ev)
{
        ev->signaled = false;
}

/* Assumes that p is current. */
int kfd_reset_event(struct kfd_process *p, uint32_t event_id)
{
        int ret = 0;
        struct kfd_event *ev;

        mutex_lock(&p->event_mutex);

        ev = lookup_event_by_id(p, event_id);

        if (ev && event_can_be_cpu_signaled(ev))
                reset_event(ev);
        else
                ret = -EINVAL;

        mutex_unlock(&p->event_mutex);
        return ret;

}

static void acknowledge_signal(struct kfd_process *p, struct kfd_event *ev)
{
        page_slots(ev->signal_page)[ev->signal_slot_index] =
                                                UNSIGNALED_EVENT_SLOT;
}

static bool is_slot_signaled(struct signal_page *page, unsigned int index)
{
        return page_slots(page)[index] != UNSIGNALED_EVENT_SLOT;
}

static void set_event_from_interrupt(struct kfd_process *p,
                                        struct kfd_event *ev)
{
        if (ev && event_can_be_gpu_signaled(ev)) {
                acknowledge_signal(p, ev);
                set_event(ev);
        }
}

void kfd_signal_event_interrupt(unsigned int pasid, uint32_t partial_id,
                                uint32_t valid_id_bits)
{
        struct kfd_event *ev;

        /*
         * Because we are called from arbitrary context (workqueue) as opposed
         * to process context, kfd_process could attempt to exit while we are
         * running so the lookup function returns a locked process.
         */
        struct kfd_process *p = kfd_lookup_process_by_pasid(pasid);

        if (!p)
                return; /* Presumably process exited. */

        mutex_lock(&p->event_mutex);

        if (valid_id_bits >= INTERRUPT_DATA_BITS) {
                /* Partial ID is a full ID. */
                ev = lookup_event_by_id(p, partial_id);
                set_event_from_interrupt(p, ev);
        } else {
                /*
                 * Partial ID is in fact partial. For now we completely
                 * ignore it, but we could use any bits we did receive to
                 * search faster.
                 */
                struct signal_page *page;
                unsigned i;

                list_for_each_entry(page, &p->signal_event_pages, event_pages)
                        for (i = 0; i < SLOTS_PER_PAGE; i++)
                                if (is_slot_signaled(page, i)) {
                                        ev = lookup_event_by_page_slot(p,
                                                                page, i);
                                        set_event_from_interrupt(p, ev);
                                }
        }

        mutex_unlock(&p->event_mutex);
        mutex_unlock(&p->mutex);
}

static struct kfd_event_waiter *alloc_event_waiters(uint32_t num_events)
{
        struct kfd_event_waiter *event_waiters;
        uint32_t i;

        event_waiters = kmalloc_array(num_events,
                                        sizeof(struct kfd_event_waiter),
                                        GFP_KERNEL);

        for (i = 0; (event_waiters) && (i < num_events) ; i++) {
                INIT_LIST_HEAD(&event_waiters[i].waiters);
                event_waiters[i].sleeping_task = current;
                event_waiters[i].activated = false;
        }

        return event_waiters;
}

static int init_event_waiter(struct kfd_process *p,
                struct kfd_event_waiter *waiter,
                uint32_t event_id,
                uint32_t input_index)
{
        struct kfd_event *ev = lookup_event_by_id(p, event_id);

        if (!ev)
                return -EINVAL;

        waiter->event = ev;
        waiter->input_index = input_index;
        waiter->activated = ev->signaled;
        ev->signaled = ev->signaled && !ev->auto_reset;

        list_add(&waiter->waiters, &ev->waiters);

        return 0;
}

static bool test_event_condition(bool all, uint32_t num_events,
                                struct kfd_event_waiter *event_waiters)
{
        uint32_t i;
        uint32_t activated_count = 0;

        for (i = 0; i < num_events; i++) {
                if (event_waiters[i].activated) {
                        if (!all)
                                return true;

                        activated_count++;
                }
        }

        return activated_count == num_events;
}

/*
 * Copy event specific data, if defined.
 * Currently only memory exception events have additional data to copy to user
 */
static bool copy_signaled_event_data(uint32_t num_events,
                struct kfd_event_waiter *event_waiters,
                struct kfd_event_data __user *data)
{
        struct kfd_hsa_memory_exception_data *src;
        struct kfd_hsa_memory_exception_data __user *dst;
        struct kfd_event_waiter *waiter;
        struct kfd_event *event;
        uint32_t i;

        for (i = 0; i < num_events; i++) {
                waiter = &event_waiters[i];
                event = waiter->event;
                if (waiter->activated && event->type == KFD_EVENT_TYPE_MEMORY) {
                        dst = &data[waiter->input_index].memory_exception_data;
                        src = &event->memory_exception_data;
                        if (copy_to_user(dst, src,
                                sizeof(struct kfd_hsa_memory_exception_data)))
                                return false;
                }
        }

        return true;

}



static long user_timeout_to_jiffies(uint32_t user_timeout_ms)
{
        if (user_timeout_ms == KFD_EVENT_TIMEOUT_IMMEDIATE)
                return 0;

        if (user_timeout_ms == KFD_EVENT_TIMEOUT_INFINITE)
                return MAX_SCHEDULE_TIMEOUT;

        /*
         * msecs_to_jiffies interprets all values above 2^31-1 as infinite,
         * but we consider them finite.
         * This hack is wrong, but nobody is likely to notice.
         */
        user_timeout_ms = min_t(uint32_t, user_timeout_ms, 0x7FFFFFFF);

        return msecs_to_jiffies(user_timeout_ms) + 1;
}

static void free_waiters(uint32_t num_events, struct kfd_event_waiter *waiters)
{
        uint32_t i;

        for (i = 0; i < num_events; i++)
                list_del(&waiters[i].waiters);

        kfree(waiters);
}

int kfd_wait_on_events(struct kfd_process *p,
                       uint32_t num_events, void __user *data,
                       bool all, uint32_t user_timeout_ms,
                       enum kfd_event_wait_result *wait_result)
{
        struct kfd_event_data __user *events =
                        (struct kfd_event_data __user *) data;
        uint32_t i;
        int ret = 0;
        struct kfd_event_waiter *event_waiters = NULL;
        long timeout = user_timeout_to_jiffies(user_timeout_ms);

        mutex_lock(&p->event_mutex);

        event_waiters = alloc_event_waiters(num_events);
        if (!event_waiters) {
                ret = -ENOMEM;
                goto fail;
        }

        for (i = 0; i < num_events; i++) {
                struct kfd_event_data event_data;

                if (copy_from_user(&event_data, &events[i],
                                sizeof(struct kfd_event_data))) {
                        ret = -EFAULT;
                        goto fail;
                }

                ret = init_event_waiter(p, &event_waiters[i],
                                event_data.event_id, i);
                if (ret)
                        goto fail;
        }

        mutex_unlock(&p->event_mutex);

        while (true) {
                if (fatal_signal_pending(current)) {
                        ret = -EINTR;
                        break;
                }

                if (signal_pending(current)) {
                        /*
                         * This is wrong when a nonzero, non-infinite timeout
                         * is specified. We need to use
                         * ERESTARTSYS_RESTARTBLOCK, but struct restart_block
                         * contains a union with data for each user and it's
                         * in generic kernel code that I don't want to
                         * touch yet.
                         */
                        ret = -ERESTARTSYS;
                        break;
                }

                if (test_event_condition(all, num_events, event_waiters)) {
                        if (copy_signaled_event_data(num_events,
                                        event_waiters, events))
                                *wait_result = KFD_WAIT_COMPLETE;
                        else
                                *wait_result = KFD_WAIT_ERROR;
                        break;
                }

                if (timeout <= 0) {
                        *wait_result = KFD_WAIT_TIMEOUT;
                        break;
                }

                timeout = schedule_timeout_interruptible(timeout);
        }
        __set_current_state(TASK_RUNNING);

        mutex_lock(&p->event_mutex);
        free_waiters(num_events, event_waiters);
        mutex_unlock(&p->event_mutex);

        return ret;

fail:
        if (event_waiters)
                free_waiters(num_events, event_waiters);

        mutex_unlock(&p->event_mutex);

        *wait_result = KFD_WAIT_ERROR;

        return ret;
}

int kfd_event_mmap(struct kfd_process *p, struct vm_area_struct *vma)
{

        unsigned int page_index;
        unsigned long pfn;
        struct signal_page *page;

        /* check required size is logical */
        if (get_order(KFD_SIGNAL_EVENT_LIMIT * 8) !=
                        get_order(vma->vm_end - vma->vm_start)) {
                pr_err("amdkfd: event page mmap requested illegal size\n");
                return -EINVAL;
        }

        page_index = vma->vm_pgoff;

        page = lookup_signal_page_by_index(p, page_index);
        if (!page) {
                /* Probably KFD bug, but mmap is user-accessible. */
                pr_debug("signal page could not be found for page_index %u\n",
                                page_index);
                return -EINVAL;
        }

        pfn = __pa(page->kernel_address);
        pfn >>= PAGE_SHIFT;

        vma->vm_flags |= VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_NORESERVE
                       | VM_DONTDUMP | VM_PFNMAP;

        pr_debug("mapping signal page\n");
        pr_debug("     start user address  == 0x%08lx\n", vma->vm_start);
        pr_debug("     end user address    == 0x%08lx\n", vma->vm_end);
        pr_debug("     pfn                 == 0x%016lX\n", pfn);
        pr_debug("     vm_flags            == 0x%08lX\n", vma->vm_flags);
        pr_debug("     size                == 0x%08lX\n",
                        vma->vm_end - vma->vm_start);

        page->user_address = (uint64_t __user *)vma->vm_start;

        /* mapping the page to user process */
        return remap_pfn_range(vma, vma->vm_start, pfn,
                        vma->vm_end - vma->vm_start, vma->vm_page_prot);
}

/*
 * Assumes that p->event_mutex is held and of course
 * that p is not going away (current or locked).
 */
static void lookup_events_by_type_and_signal(struct kfd_process *p,
                int type, void *event_data)
{
        struct kfd_hsa_memory_exception_data *ev_data;
        struct kfd_event *ev;
        int bkt;
        bool send_signal = true;

        ev_data = (struct kfd_hsa_memory_exception_data *) event_data;

        hash_for_each(p->events, bkt, ev, events)
                if (ev->type == type) {
                        send_signal = false;
                        dev_dbg(kfd_device,
                                        "Event found: id %X type %d",
                                        ev->event_id, ev->type);
                        set_event(ev);
                        if (ev->type == KFD_EVENT_TYPE_MEMORY && ev_data)
                                ev->memory_exception_data = *ev_data;
                }

        /* Send SIGTERM no event of type "type" has been found*/
        if (send_signal) {
                if (send_sigterm) {
                        dev_warn(kfd_device,
                                "Sending SIGTERM to HSA Process with PID %d ",
                                        p->lead_thread->pid);
                        send_sig(SIGTERM, p->lead_thread, 0);
                } else {
                        dev_err(kfd_device,
                                "HSA Process (PID %d) got unhandled exception",
                                p->lead_thread->pid);
                }
        }
}

void kfd_signal_iommu_event(struct kfd_dev *dev, unsigned int pasid,
                unsigned long address, bool is_write_requested,
                bool is_execute_requested)
{
        struct kfd_hsa_memory_exception_data memory_exception_data;
        struct vm_area_struct *vma;

        /*
         * Because we are called from arbitrary context (workqueue) as opposed
         * to process context, kfd_process could attempt to exit while we are
         * running so the lookup function returns a locked process.
         */
        struct kfd_process *p = kfd_lookup_process_by_pasid(pasid);

        if (!p)
                return; /* Presumably process exited. */

        memset(&memory_exception_data, 0, sizeof(memory_exception_data));

        down_read(&p->mm->mmap_sem);
        vma = find_vma(p->mm, address);

        memory_exception_data.gpu_id = dev->id;
        memory_exception_data.va = address;
        /* Set failure reason */
        memory_exception_data.failure.NotPresent = 1;
        memory_exception_data.failure.NoExecute = 0;
        memory_exception_data.failure.ReadOnly = 0;
        if (vma) {
                if (vma->vm_start > address) {
                        memory_exception_data.failure.NotPresent = 1;
                        memory_exception_data.failure.NoExecute = 0;
                        memory_exception_data.failure.ReadOnly = 0;
                } else {
                        memory_exception_data.failure.NotPresent = 0;
                        if (is_write_requested && !(vma->vm_flags & VM_WRITE))
                                memory_exception_data.failure.ReadOnly = 1;
                        else
                                memory_exception_data.failure.ReadOnly = 0;
                        if (is_execute_requested && !(vma->vm_flags & VM_EXEC))
                                memory_exception_data.failure.NoExecute = 1;
                        else
                                memory_exception_data.failure.NoExecute = 0;
                }
        }

        up_read(&p->mm->mmap_sem);

        mutex_lock(&p->event_mutex);

        /* Lookup events by type and signal them */
        lookup_events_by_type_and_signal(p, KFD_EVENT_TYPE_MEMORY,
                        &memory_exception_data);

        mutex_unlock(&p->event_mutex);
        mutex_unlock(&p->mutex);
}

void kfd_signal_hw_exception_event(unsigned int pasid)
{
        /*
         * Because we are called from arbitrary context (workqueue) as opposed
         * to process context, kfd_process could attempt to exit while we are
         * running so the lookup function returns a locked process.
         */
        struct kfd_process *p = kfd_lookup_process_by_pasid(pasid);

        if (!p)
                return; /* Presumably process exited. */

        mutex_lock(&p->event_mutex);

        /* Lookup events by type and signal them */
        lookup_events_by_type_and_signal(p, KFD_EVENT_TYPE_HW_EXCEPTION, NULL);

        mutex_unlock(&p->event_mutex);
        mutex_unlock(&p->mutex);
}