drivers/staging/gasket/gasket_ioctl.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (C) 2018 Google, Inc. */
 #include "gasket.h"
 #include "gasket_ioctl.h"
 #include "gasket_constants.h"
 #include "gasket_core.h"
 #include "gasket_interrupt.h"
 #include "gasket_page_table.h"
 #include <linux/compiler.h>
 #include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>

 #ifdef GASKET_KERNEL_TRACE_SUPPORT
 #define CREATE_TRACE_POINTS
 #include <trace/events/gasket_ioctl.h>
 #else
 #define trace_gasket_ioctl_entry(x, ...)
 #define trace_gasket_ioctl_exit(x)
 #define trace_gasket_ioctl_integer_data(x)
 #define trace_gasket_ioctl_eventfd_data(x, ...)
 #define trace_gasket_ioctl_page_table_data(x, ...)
 #define trace_gasket_ioctl_config_coherent_allocator(x, ...)
 #endif

 /* Associate an eventfd with an interrupt. */
 static int gasket_set_event_fd(struct gasket_dev *gasket_dev,
 			       struct gasket_interrupt_eventfd __user *argp)
 {
 	struct gasket_interrupt_eventfd die;

 	if (copy_from_user(&die, argp, sizeof(struct gasket_interrupt_eventfd)))
 		return -EFAULT;

 	trace_gasket_ioctl_eventfd_data(die.interrupt, die.event_fd);

 	return gasket_interrupt_set_eventfd(gasket_dev->interrupt_data,
 					    die.interrupt, die.event_fd);
 }

 /* Read the size of the page table. */
 static int gasket_read_page_table_size(struct gasket_dev *gasket_dev,
 	struct gasket_page_table_ioctl __user *argp)
 {
 	int ret = 0;
 	struct gasket_page_table_ioctl ibuf;

 	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
 		return -EFAULT;

 	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
 		return -EFAULT;

 	ibuf.size = gasket_page_table_num_entries(
 		gasket_dev->page_table[ibuf.page_table_index]);

 	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
 					   ibuf.host_address,
 					   ibuf.device_address);

 	if (copy_to_user(argp, &ibuf, sizeof(ibuf)))
 		return -EFAULT;

 	return ret;
 }

 /* Read the size of the simple page table. */
 static int gasket_read_simple_page_table_size(struct gasket_dev *gasket_dev,
 	struct gasket_page_table_ioctl __user *argp)
 {
 	int ret = 0;
 	struct gasket_page_table_ioctl ibuf;

 	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
 		return -EFAULT;

 	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
 		return -EFAULT;

 	ibuf.size =
 		gasket_page_table_num_simple_entries(gasket_dev->page_table[ibuf.page_table_index]);

 	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
 					   ibuf.host_address,
 					   ibuf.device_address);

 	if (copy_to_user(argp, &ibuf, sizeof(ibuf)))
 		return -EFAULT;

 	return ret;
 }

 /* Set the boundary between the simple and extended page tables. */
 static int gasket_partition_page_table(struct gasket_dev *gasket_dev,
 	struct gasket_page_table_ioctl __user *argp)
 {
 	int ret;
 	struct gasket_page_table_ioctl ibuf;
 	uint max_page_table_size;

 	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
 		return -EFAULT;

 	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
 					   ibuf.host_address,
 					   ibuf.device_address);

 	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
 		return -EFAULT;
 	max_page_table_size = gasket_page_table_max_size(
 		gasket_dev->page_table[ibuf.page_table_index]);

 	if (ibuf.size > max_page_table_size) {
 		dev_dbg(gasket_dev->dev,
 			"Partition request 0x%llx too large, max is 0x%x\n",
 			ibuf.size, max_page_table_size);
 		return -EINVAL;
 	}

 	mutex_lock(&gasket_dev->mutex);

 	ret = gasket_page_table_partition(
 		gasket_dev->page_table[ibuf.page_table_index], ibuf.size);
 	mutex_unlock(&gasket_dev->mutex);

 	return ret;
 }

 /* Map a userspace buffer to a device virtual address. */
 static int gasket_map_buffers(struct gasket_dev *gasket_dev,
 			      struct gasket_page_table_ioctl __user *argp)
 {
 	struct gasket_page_table_ioctl ibuf;

 	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
 		return -EFAULT;

 	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
 					   ibuf.host_address,
 					   ibuf.device_address);

 	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
 		return -EFAULT;

 	if (gasket_page_table_are_addrs_bad(gasket_dev->page_table[ibuf.page_table_index],
 					    ibuf.host_address,
 					    ibuf.device_address, ibuf.size))
 		return -EINVAL;

 	return gasket_page_table_map(gasket_dev->page_table[ibuf.page_table_index],
 				     ibuf.host_address, ibuf.device_address,
 				     ibuf.size / PAGE_SIZE);
 }

 /* Unmap a userspace buffer from a device virtual address. */
 static int gasket_unmap_buffers(struct gasket_dev *gasket_dev,
 				struct gasket_page_table_ioctl __user *argp)
 {
 	struct gasket_page_table_ioctl ibuf;

 	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
 		return -EFAULT;

 	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
 					   ibuf.host_address,
 					   ibuf.device_address);

 	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
 		return -EFAULT;

 	if (gasket_page_table_is_dev_addr_bad(gasket_dev->page_table[ibuf.page_table_index],
 					      ibuf.device_address, ibuf.size))
 		return -EINVAL;

 	gasket_page_table_unmap(gasket_dev->page_table[ibuf.page_table_index],
 				ibuf.device_address, ibuf.size / PAGE_SIZE);

 	return 0;
 }

 /*
  * Reserve structures for coherent allocation, and allocate or free the
  * corresponding memory.
  */
 static int gasket_config_coherent_allocator(struct gasket_dev *gasket_dev,
 	struct gasket_coherent_alloc_config_ioctl __user *argp)
 {
 	int ret;
 	struct gasket_coherent_alloc_config_ioctl ibuf;

 	if (copy_from_user(&ibuf, argp,
 			   sizeof(struct gasket_coherent_alloc_config_ioctl)))
 		return -EFAULT;

 	trace_gasket_ioctl_config_coherent_allocator(ibuf.enable, ibuf.size,
 						     ibuf.dma_address);

 	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
 		return -EFAULT;

 	if (ibuf.size > PAGE_SIZE * MAX_NUM_COHERENT_PAGES)
 		return -ENOMEM;

 	if (ibuf.enable == 0) {
 		ret = gasket_free_coherent_memory(gasket_dev, ibuf.size,
 						  ibuf.dma_address,
 						  ibuf.page_table_index);
 	} else {
 		ret = gasket_alloc_coherent_memory(gasket_dev, ibuf.size,
 						   &ibuf.dma_address,
 						   ibuf.page_table_index);
 	}
 	if (ret)
 		return ret;
 	if (copy_to_user(argp, &ibuf, sizeof(ibuf)))
 		return -EFAULT;

 	return 0;
 }

 /* Check permissions for Gasket ioctls. */
 static bool gasket_ioctl_check_permissions(struct file *filp, uint cmd)
 {
 	bool alive;
 	bool read, write;
 	struct gasket_dev *gasket_dev = (struct gasket_dev *)filp->private_data;

 	alive = (gasket_dev->status == GASKET_STATUS_ALIVE);
 	if (!alive)
 		dev_dbg(gasket_dev->dev, "%s alive %d status %d\n",
 			__func__, alive, gasket_dev->status);

 	read = !!(filp->f_mode & FMODE_READ);
 	write = !!(filp->f_mode & FMODE_WRITE);

 	switch (cmd) {
 	case GASKET_IOCTL_RESET:
 	case GASKET_IOCTL_CLEAR_INTERRUPT_COUNTS:
 		return write;

 	case GASKET_IOCTL_PAGE_TABLE_SIZE:
 	case GASKET_IOCTL_SIMPLE_PAGE_TABLE_SIZE:
 	case GASKET_IOCTL_NUMBER_PAGE_TABLES:
 		return read;

 	case GASKET_IOCTL_PARTITION_PAGE_TABLE:
 	case GASKET_IOCTL_CONFIG_COHERENT_ALLOCATOR:
 		return alive && write;

 	case GASKET_IOCTL_MAP_BUFFER:
 	case GASKET_IOCTL_UNMAP_BUFFER:
 		return alive && write;

 	case GASKET_IOCTL_CLEAR_EVENTFD:
 	case GASKET_IOCTL_SET_EVENTFD:
 		return alive && write;
 	}

 	return false; /* unknown permissions */
 }

 /*
  * standard ioctl dispatch function.
  * @filp: File structure pointer describing this node usage session.
  * @cmd: ioctl number to handle.
  * @argp: ioctl-specific data pointer.
  *
  * Standard ioctl dispatcher; forwards operations to individual handlers.
  */
 long gasket_handle_ioctl(struct file *filp, uint cmd, void __user *argp)
 {
 	struct gasket_dev *gasket_dev;
 	unsigned long arg = (unsigned long)argp;
 	gasket_ioctl_permissions_cb_t ioctl_permissions_cb;
 	int retval;

 	gasket_dev = (struct gasket_dev *)filp->private_data;
 	trace_gasket_ioctl_entry(gasket_dev->dev_info.name, cmd);

 	ioctl_permissions_cb = gasket_get_ioctl_permissions_cb(gasket_dev);
 	if (ioctl_permissions_cb) {
 		retval = ioctl_permissions_cb(filp, cmd, argp);
 		if (retval < 0) {
 			trace_gasket_ioctl_exit(retval);
 			return retval;
 		} else if (retval == 0) {
 			trace_gasket_ioctl_exit(-EPERM);
 			return -EPERM;
 		}
 	} else if (!gasket_ioctl_check_permissions(filp, cmd)) {
 		trace_gasket_ioctl_exit(-EPERM);
 		dev_dbg(gasket_dev->dev, "ioctl cmd=%x noperm\n", cmd);
 		return -EPERM;
 	}

 	/* Tracing happens in this switch statement for all ioctls with
 	 * an integer argrument, but ioctls with a struct argument
 	 * that needs copying and decoding, that tracing is done within
 	 * the handler call.
 	 */
 	switch (cmd) {
 	case GASKET_IOCTL_RESET:
 		retval = gasket_reset(gasket_dev);
 		break;
 	case GASKET_IOCTL_SET_EVENTFD:
 		retval = gasket_set_event_fd(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_CLEAR_EVENTFD:
 		trace_gasket_ioctl_integer_data(arg);
 		retval =
 			gasket_interrupt_clear_eventfd(gasket_dev->interrupt_data,
 						       (int)arg);
 		break;
 	case GASKET_IOCTL_PARTITION_PAGE_TABLE:
 		trace_gasket_ioctl_integer_data(arg);
 		retval = gasket_partition_page_table(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_NUMBER_PAGE_TABLES:
 		trace_gasket_ioctl_integer_data(gasket_dev->num_page_tables);
 		if (copy_to_user(argp, &gasket_dev->num_page_tables,
 				 sizeof(uint64_t)))
 			retval = -EFAULT;
 		else
 			retval = 0;
 		break;
 	case GASKET_IOCTL_PAGE_TABLE_SIZE:
 		retval = gasket_read_page_table_size(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_SIMPLE_PAGE_TABLE_SIZE:
 		retval = gasket_read_simple_page_table_size(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_MAP_BUFFER:
 		retval = gasket_map_buffers(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_CONFIG_COHERENT_ALLOCATOR:
 		retval = gasket_config_coherent_allocator(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_UNMAP_BUFFER:
 		retval = gasket_unmap_buffers(gasket_dev, argp);
 		break;
 	case GASKET_IOCTL_CLEAR_INTERRUPT_COUNTS:
 		/* Clear interrupt counts doesn't take an arg, so use 0. */
 		trace_gasket_ioctl_integer_data(0);
 		retval = gasket_interrupt_reset_counts(gasket_dev);
 		break;
 	default:
 		/* If we don't understand the ioctl, the best we can do is trace
 		 * the arg.
 		 */
 		trace_gasket_ioctl_integer_data(arg);
 		dev_dbg(gasket_dev->dev,
 			"Unknown ioctl cmd=0x%x not caught by gasket_is_supported_ioctl\n",
 			cmd);
 		retval = -EINVAL;
 		break;
 	}

 	trace_gasket_ioctl_exit(retval);
 	return retval;
 }

 /*
  * Determines if an ioctl is part of the standard Gasket framework.
  * @cmd: The ioctl number to handle.
  *
  * Returns 1 if the ioctl is supported and 0 otherwise.
  */
 long gasket_is_supported_ioctl(uint cmd)
 {
 	switch (cmd) {
 	case GASKET_IOCTL_RESET:
 	case GASKET_IOCTL_SET_EVENTFD:
 	case GASKET_IOCTL_CLEAR_EVENTFD:
 	case GASKET_IOCTL_PARTITION_PAGE_TABLE:
 	case GASKET_IOCTL_NUMBER_PAGE_TABLES:
 	case GASKET_IOCTL_PAGE_TABLE_SIZE:
 	case GASKET_IOCTL_SIMPLE_PAGE_TABLE_SIZE:
 	case GASKET_IOCTL_MAP_BUFFER:
 	case GASKET_IOCTL_UNMAP_BUFFER:
 	case GASKET_IOCTL_CLEAR_INTERRUPT_COUNTS:
 	case GASKET_IOCTL_CONFIG_COHERENT_ALLOCATOR:
 		return 1;
 	default:
 		return 0;
 	}
 }
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright (C) 2018 Google, Inc. */
	#include "gasket.h"
	#include "gasket_ioctl.h"
	#include "gasket_constants.h"
	#include "gasket_core.h"
	#include "gasket_interrupt.h"
	#include "gasket_page_table.h"
	#include <linux/compiler.h>
	#include <linux/device.h>
	#include <linux/fs.h>
	#include <linux/uaccess.h>

	#ifdef GASKET_KERNEL_TRACE_SUPPORT
	#define CREATE_TRACE_POINTS
	#include <trace/events/gasket_ioctl.h>
	#else
	#define trace_gasket_ioctl_entry(x, ...)
	#define trace_gasket_ioctl_exit(x)
	#define trace_gasket_ioctl_integer_data(x)
	#define trace_gasket_ioctl_eventfd_data(x, ...)
	#define trace_gasket_ioctl_page_table_data(x, ...)
	#define trace_gasket_ioctl_config_coherent_allocator(x, ...)
	#endif

	/* Associate an eventfd with an interrupt. */
	static int gasket_set_event_fd(struct gasket_dev *gasket_dev,
	struct gasket_interrupt_eventfd __user *argp)
	{
	struct gasket_interrupt_eventfd die;

	if (copy_from_user(&die, argp, sizeof(struct gasket_interrupt_eventfd)))
	return -EFAULT;

	trace_gasket_ioctl_eventfd_data(die.interrupt, die.event_fd);

	return gasket_interrupt_set_eventfd(gasket_dev->interrupt_data,
	die.interrupt, die.event_fd);
	}

	/* Read the size of the page table. */
	static int gasket_read_page_table_size(struct gasket_dev *gasket_dev,
	struct gasket_page_table_ioctl __user *argp)
	{
	int ret = 0;
	struct gasket_page_table_ioctl ibuf;

	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
	return -EFAULT;

	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
	return -EFAULT;

	ibuf.size = gasket_page_table_num_entries(
	gasket_dev->page_table[ibuf.page_table_index]);

	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
	ibuf.host_address,
	ibuf.device_address);

	if (copy_to_user(argp, &ibuf, sizeof(ibuf)))
	return -EFAULT;

	return ret;
	}

	/* Read the size of the simple page table. */
	static int gasket_read_simple_page_table_size(struct gasket_dev *gasket_dev,
	struct gasket_page_table_ioctl __user *argp)
	{
	int ret = 0;
	struct gasket_page_table_ioctl ibuf;

	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
	return -EFAULT;

	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
	return -EFAULT;

	ibuf.size =
	gasket_page_table_num_simple_entries(gasket_dev->page_table[ibuf.page_table_index]);

	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
	ibuf.host_address,
	ibuf.device_address);

	if (copy_to_user(argp, &ibuf, sizeof(ibuf)))
	return -EFAULT;

	return ret;
	}

	/* Set the boundary between the simple and extended page tables. */
	static int gasket_partition_page_table(struct gasket_dev *gasket_dev,
	struct gasket_page_table_ioctl __user *argp)
	{
	int ret;
	struct gasket_page_table_ioctl ibuf;
	uint max_page_table_size;

	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
	return -EFAULT;

	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
	ibuf.host_address,
	ibuf.device_address);

	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
	return -EFAULT;
	max_page_table_size = gasket_page_table_max_size(
	gasket_dev->page_table[ibuf.page_table_index]);

	if (ibuf.size > max_page_table_size) {
	dev_dbg(gasket_dev->dev,
	"Partition request 0x%llx too large, max is 0x%x\n",
	ibuf.size, max_page_table_size);
	return -EINVAL;
	}

	mutex_lock(&gasket_dev->mutex);

	ret = gasket_page_table_partition(
	gasket_dev->page_table[ibuf.page_table_index], ibuf.size);
	mutex_unlock(&gasket_dev->mutex);

	return ret;
	}

	/* Map a userspace buffer to a device virtual address. */
	static int gasket_map_buffers(struct gasket_dev *gasket_dev,
	struct gasket_page_table_ioctl __user *argp)
	{
	struct gasket_page_table_ioctl ibuf;

	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
	return -EFAULT;

	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
	ibuf.host_address,
	ibuf.device_address);

	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
	return -EFAULT;

	if (gasket_page_table_are_addrs_bad(gasket_dev->page_table[ibuf.page_table_index],
	ibuf.host_address,
	ibuf.device_address, ibuf.size))
	return -EINVAL;

	return gasket_page_table_map(gasket_dev->page_table[ibuf.page_table_index],
	ibuf.host_address, ibuf.device_address,
	ibuf.size / PAGE_SIZE);
	}

	/* Unmap a userspace buffer from a device virtual address. */
	static int gasket_unmap_buffers(struct gasket_dev *gasket_dev,
	struct gasket_page_table_ioctl __user *argp)
	{
	struct gasket_page_table_ioctl ibuf;

	if (copy_from_user(&ibuf, argp, sizeof(struct gasket_page_table_ioctl)))
	return -EFAULT;

	trace_gasket_ioctl_page_table_data(ibuf.page_table_index, ibuf.size,
	ibuf.host_address,
	ibuf.device_address);

	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
	return -EFAULT;

	if (gasket_page_table_is_dev_addr_bad(gasket_dev->page_table[ibuf.page_table_index],
	ibuf.device_address, ibuf.size))
	return -EINVAL;

	gasket_page_table_unmap(gasket_dev->page_table[ibuf.page_table_index],
	ibuf.device_address, ibuf.size / PAGE_SIZE);

	return 0;
	}

	/*
	* Reserve structures for coherent allocation, and allocate or free the
	* corresponding memory.
	*/
	static int gasket_config_coherent_allocator(struct gasket_dev *gasket_dev,
	struct gasket_coherent_alloc_config_ioctl __user *argp)
	{
	int ret;
	struct gasket_coherent_alloc_config_ioctl ibuf;

	if (copy_from_user(&ibuf, argp,
	sizeof(struct gasket_coherent_alloc_config_ioctl)))
	return -EFAULT;

	trace_gasket_ioctl_config_coherent_allocator(ibuf.enable, ibuf.size,
	ibuf.dma_address);

	if (ibuf.page_table_index >= gasket_dev->num_page_tables)
	return -EFAULT;

	if (ibuf.size > PAGE_SIZE * MAX_NUM_COHERENT_PAGES)
	return -ENOMEM;

	if (ibuf.enable == 0) {
	ret = gasket_free_coherent_memory(gasket_dev, ibuf.size,
	ibuf.dma_address,
	ibuf.page_table_index);
	} else {
	ret = gasket_alloc_coherent_memory(gasket_dev, ibuf.size,
	&ibuf.dma_address,
	ibuf.page_table_index);
	}
	if (ret)
	return ret;
	if (copy_to_user(argp, &ibuf, sizeof(ibuf)))
	return -EFAULT;

	return 0;
	}

	/* Check permissions for Gasket ioctls. */
	static bool gasket_ioctl_check_permissions(struct file *filp, uint cmd)
	{
	bool alive;
	bool read, write;
	struct gasket_dev gasket_dev = (struct gasket_dev )filp->private_data;

	alive = (gasket_dev->status == GASKET_STATUS_ALIVE);
	if (!alive)
	dev_dbg(gasket_dev->dev, "%s alive %d status %d\n",
	__func__, alive, gasket_dev->status);

	read = !!(filp->f_mode & FMODE_READ);
	write = !!(filp->f_mode & FMODE_WRITE);

	switch (cmd) {
	case GASKET_IOCTL_RESET:
	case GASKET_IOCTL_CLEAR_INTERRUPT_COUNTS:
	return write;

	case GASKET_IOCTL_PAGE_TABLE_SIZE:
	case GASKET_IOCTL_SIMPLE_PAGE_TABLE_SIZE:
	case GASKET_IOCTL_NUMBER_PAGE_TABLES:
	return read;

	case GASKET_IOCTL_PARTITION_PAGE_TABLE:
	case GASKET_IOCTL_CONFIG_COHERENT_ALLOCATOR:
	return alive && write;

	case GASKET_IOCTL_MAP_BUFFER:
	case GASKET_IOCTL_UNMAP_BUFFER:
	return alive && write;

	case GASKET_IOCTL_CLEAR_EVENTFD:
	case GASKET_IOCTL_SET_EVENTFD:
	return alive && write;
	}

	return false; /* unknown permissions */
	}

	/*
	* standard ioctl dispatch function.
	* @filp: File structure pointer describing this node usage session.
	* @cmd: ioctl number to handle.
	* @argp: ioctl-specific data pointer.
	*
	* Standard ioctl dispatcher; forwards operations to individual handlers.
	*/
	long gasket_handle_ioctl(struct file filp, uint cmd, void __user argp)
	{
	struct gasket_dev *gasket_dev;
	unsigned long arg = (unsigned long)argp;
	gasket_ioctl_permissions_cb_t ioctl_permissions_cb;
	int retval;

	gasket_dev = (struct gasket_dev *)filp->private_data;
	trace_gasket_ioctl_entry(gasket_dev->dev_info.name, cmd);

	ioctl_permissions_cb = gasket_get_ioctl_permissions_cb(gasket_dev);
	if (ioctl_permissions_cb) {
	retval = ioctl_permissions_cb(filp, cmd, argp);
	if (retval < 0) {
	trace_gasket_ioctl_exit(retval);
	return retval;
	} else if (retval == 0) {
	trace_gasket_ioctl_exit(-EPERM);
	return -EPERM;
	}
	} else if (!gasket_ioctl_check_permissions(filp, cmd)) {
	trace_gasket_ioctl_exit(-EPERM);
	dev_dbg(gasket_dev->dev, "ioctl cmd=%x noperm\n", cmd);
	return -EPERM;
	}

	/* Tracing happens in this switch statement for all ioctls with
	* an integer argrument, but ioctls with a struct argument
	* that needs copying and decoding, that tracing is done within
	* the handler call.
	*/
	switch (cmd) {
	case GASKET_IOCTL_RESET:
	retval = gasket_reset(gasket_dev);
	break;
	case GASKET_IOCTL_SET_EVENTFD:
	retval = gasket_set_event_fd(gasket_dev, argp);
	break;
	case GASKET_IOCTL_CLEAR_EVENTFD:
	trace_gasket_ioctl_integer_data(arg);
	retval =
	gasket_interrupt_clear_eventfd(gasket_dev->interrupt_data,
	(int)arg);
	break;
	case GASKET_IOCTL_PARTITION_PAGE_TABLE:
	trace_gasket_ioctl_integer_data(arg);
	retval = gasket_partition_page_table(gasket_dev, argp);
	break;
	case GASKET_IOCTL_NUMBER_PAGE_TABLES:
	trace_gasket_ioctl_integer_data(gasket_dev->num_page_tables);
	if (copy_to_user(argp, &gasket_dev->num_page_tables,
	sizeof(uint64_t)))
	retval = -EFAULT;
	else
	retval = 0;
	break;
	case GASKET_IOCTL_PAGE_TABLE_SIZE:
	retval = gasket_read_page_table_size(gasket_dev, argp);
	break;
	case GASKET_IOCTL_SIMPLE_PAGE_TABLE_SIZE:
	retval = gasket_read_simple_page_table_size(gasket_dev, argp);
	break;
	case GASKET_IOCTL_MAP_BUFFER:
	retval = gasket_map_buffers(gasket_dev, argp);
	break;
	case GASKET_IOCTL_CONFIG_COHERENT_ALLOCATOR:
	retval = gasket_config_coherent_allocator(gasket_dev, argp);
	break;
	case GASKET_IOCTL_UNMAP_BUFFER:
	retval = gasket_unmap_buffers(gasket_dev, argp);
	break;
	case GASKET_IOCTL_CLEAR_INTERRUPT_COUNTS:
	/* Clear interrupt counts doesn't take an arg, so use 0. */
	trace_gasket_ioctl_integer_data(0);
	retval = gasket_interrupt_reset_counts(gasket_dev);
	break;
	default:
	/* If we don't understand the ioctl, the best we can do is trace
	* the arg.
	*/
	trace_gasket_ioctl_integer_data(arg);
	dev_dbg(gasket_dev->dev,
	"Unknown ioctl cmd=0x%x not caught by gasket_is_supported_ioctl\n",
	cmd);
	retval = -EINVAL;
	break;
	}

	trace_gasket_ioctl_exit(retval);
	return retval;
	}

	/*
	* Determines if an ioctl is part of the standard Gasket framework.
	* @cmd: The ioctl number to handle.
	*
	* Returns 1 if the ioctl is supported and 0 otherwise.
	*/
	long gasket_is_supported_ioctl(uint cmd)
	{
	switch (cmd) {
	case GASKET_IOCTL_RESET:
	case GASKET_IOCTL_SET_EVENTFD:
	case GASKET_IOCTL_CLEAR_EVENTFD:
	case GASKET_IOCTL_PARTITION_PAGE_TABLE:
	case GASKET_IOCTL_NUMBER_PAGE_TABLES:
	case GASKET_IOCTL_PAGE_TABLE_SIZE:
	case GASKET_IOCTL_SIMPLE_PAGE_TABLE_SIZE:
	case GASKET_IOCTL_MAP_BUFFER:
	case GASKET_IOCTL_UNMAP_BUFFER:
	case GASKET_IOCTL_CLEAR_INTERRUPT_COUNTS:
	case GASKET_IOCTL_CONFIG_COHERENT_ALLOCATOR:
	return 1;
	default:
	return 0;
	}
	}