arch/x86/kernel/cpu/mtrr/if.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include <linux/capability.h>
 #include <linux/seq_file.h>
 #include <linux/uaccess.h>
 #include <linux/proc_fs.h>
 #include <linux/ctype.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/init.h>

 #define LINE_SIZE 80

 #include <asm/mtrr.h>

 #include "mtrr.h"

 #define FILE_FCOUNT(f) (((struct seq_file *)((f)->private_data))->private)

 static const char *const mtrr_strings[MTRR_NUM_TYPES] =
 {
 	"uncachable",		/* 0 */
 	"write-combining",	/* 1 */
 	"?",			/* 2 */
 	"?",			/* 3 */
 	"write-through",	/* 4 */
 	"write-protect",	/* 5 */
 	"write-back",		/* 6 */
 };

 const char *mtrr_attrib_to_str(int x)
 {
 	return (x <= 6) ? mtrr_strings[x] : "?";
 }

 #ifdef CONFIG_PROC_FS

 static int
 mtrr_file_add(unsigned long base, unsigned long size,
 	      unsigned int type, bool increment, struct file *file, int page)
 {
 	unsigned int *fcount = FILE_FCOUNT(file);
 	int reg, max;

 	max = num_var_ranges;
 	if (fcount == NULL) {
 		fcount = kcalloc(max, sizeof(*fcount), GFP_KERNEL);
 		if (!fcount)
 			return -ENOMEM;
 		FILE_FCOUNT(file) = fcount;
 	}
 	if (!page) {
 		if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1)))
 			return -EINVAL;
 		base >>= PAGE_SHIFT;
 		size >>= PAGE_SHIFT;
 	}
 	reg = mtrr_add_page(base, size, type, true);
 	if (reg >= 0)
 		++fcount[reg];
 	return reg;
 }

 static int
 mtrr_file_del(unsigned long base, unsigned long size,
 	      struct file *file, int page)
 {
 	unsigned int *fcount = FILE_FCOUNT(file);
 	int reg;

 	if (!page) {
 		if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1)))
 			return -EINVAL;
 		base >>= PAGE_SHIFT;
 		size >>= PAGE_SHIFT;
 	}
 	reg = mtrr_del_page(-1, base, size);
 	if (reg < 0)
 		return reg;
 	if (fcount == NULL)
 		return reg;
 	if (fcount[reg] < 1)
 		return -EINVAL;
 	--fcount[reg];
 	return reg;
 }

 /*
  * seq_file can seek but we ignore it.
  *
  * Format of control line:
  *    "base=%Lx size=%Lx type=%s" or "disable=%d"
  */
 static ssize_t
 mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
 {
 	int i, err;
 	unsigned long reg;
 	unsigned long long base, size;
 	char *ptr;
 	char line[LINE_SIZE];
 	int length;
 	size_t linelen;

 	memset(line, 0, LINE_SIZE);

 	len = min_t(size_t, len, LINE_SIZE - 1);
 	length = strncpy_from_user(line, buf, len);
 	if (length < 0)
 		return length;

 	linelen = strlen(line);
 	ptr = line + linelen - 1;
 	if (linelen && *ptr == '\n')
 		*ptr = '\0';

 	if (!strncmp(line, "disable=", 8)) {
 		reg = simple_strtoul(line + 8, &ptr, 0);
 		err = mtrr_del_page(reg, 0, 0);
 		if (err < 0)
 			return err;
 		return len;
 	}

 	if (strncmp(line, "base=", 5))
 		return -EINVAL;

 	base = simple_strtoull(line + 5, &ptr, 0);
 	ptr = skip_spaces(ptr);

 	if (strncmp(ptr, "size=", 5))
 		return -EINVAL;

 	size = simple_strtoull(ptr + 5, &ptr, 0);
 	if ((base & 0xfff) || (size & 0xfff))
 		return -EINVAL;
 	ptr = skip_spaces(ptr);

 	if (strncmp(ptr, "type=", 5))
 		return -EINVAL;
 	ptr = skip_spaces(ptr + 5);

 	i = match_string(mtrr_strings, MTRR_NUM_TYPES, ptr);
 	if (i < 0)
 		return i;

 	base >>= PAGE_SHIFT;
 	size >>= PAGE_SHIFT;
 	err = mtrr_add_page((unsigned long)base, (unsigned long)size, i, true);
 	if (err < 0)
 		return err;
 	return len;
 }

 static long
 mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
 {
 	int err = 0;
 	mtrr_type type;
 	unsigned long base;
 	unsigned long size;
 	struct mtrr_sentry sentry;
 	struct mtrr_gentry gentry;
 	void __user *arg = (void __user *) __arg;

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

 	switch (cmd) {
 	case MTRRIOC_ADD_ENTRY:
 	case MTRRIOC_SET_ENTRY:
 	case MTRRIOC_DEL_ENTRY:
 	case MTRRIOC_KILL_ENTRY:
 	case MTRRIOC_ADD_PAGE_ENTRY:
 	case MTRRIOC_SET_PAGE_ENTRY:
 	case MTRRIOC_DEL_PAGE_ENTRY:
 	case MTRRIOC_KILL_PAGE_ENTRY:
 		if (copy_from_user(&sentry, arg, sizeof(sentry)))
 			return -EFAULT;
 		break;
 	case MTRRIOC_GET_ENTRY:
 	case MTRRIOC_GET_PAGE_ENTRY:
 		if (copy_from_user(&gentry, arg, sizeof(gentry)))
 			return -EFAULT;
 		break;
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_ADD_ENTRY:
 	case MTRRIOC32_SET_ENTRY:
 	case MTRRIOC32_DEL_ENTRY:
 	case MTRRIOC32_KILL_ENTRY:
 	case MTRRIOC32_ADD_PAGE_ENTRY:
 	case MTRRIOC32_SET_PAGE_ENTRY:
 	case MTRRIOC32_DEL_PAGE_ENTRY:
 	case MTRRIOC32_KILL_PAGE_ENTRY: {
 		struct mtrr_sentry32 __user *s32;

 		s32 = (struct mtrr_sentry32 __user *)__arg;
 		err = get_user(sentry.base, &s32->base);
 		err |= get_user(sentry.size, &s32->size);
 		err |= get_user(sentry.type, &s32->type);
 		if (err)
 			return err;
 		break;
 	}
 	case MTRRIOC32_GET_ENTRY:
 	case MTRRIOC32_GET_PAGE_ENTRY: {
 		struct mtrr_gentry32 __user *g32;

 		g32 = (struct mtrr_gentry32 __user *)__arg;
 		err = get_user(gentry.regnum, &g32->regnum);
 		err |= get_user(gentry.base, &g32->base);
 		err |= get_user(gentry.size, &g32->size);
 		err |= get_user(gentry.type, &g32->type);
 		if (err)
 			return err;
 		break;
 	}
 #endif
 	}

 	switch (cmd) {
 	default:
 		return -ENOTTY;
 	case MTRRIOC_ADD_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_ADD_ENTRY:
 #endif
 		err =
 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
 				  file, 0);
 		break;
 	case MTRRIOC_SET_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_SET_ENTRY:
 #endif
 		err = mtrr_add(sentry.base, sentry.size, sentry.type, false);
 		break;
 	case MTRRIOC_DEL_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_DEL_ENTRY:
 #endif
 		err = mtrr_file_del(sentry.base, sentry.size, file, 0);
 		break;
 	case MTRRIOC_KILL_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_KILL_ENTRY:
 #endif
 		err = mtrr_del(-1, sentry.base, sentry.size);
 		break;
 	case MTRRIOC_GET_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_GET_ENTRY:
 #endif
 		if (gentry.regnum >= num_var_ranges)
 			return -EINVAL;
 		mtrr_if->get(gentry.regnum, &base, &size, &type);

 		/* Hide entries that go above 4GB */
 		if (base + size - 1 >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT))
 		    || size >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT)))
 			gentry.base = gentry.size = gentry.type = 0;
 		else {
 			gentry.base = base << PAGE_SHIFT;
 			gentry.size = size << PAGE_SHIFT;
 			gentry.type = type;
 		}

 		break;
 	case MTRRIOC_ADD_PAGE_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_ADD_PAGE_ENTRY:
 #endif
 		err =
 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
 				  file, 1);
 		break;
 	case MTRRIOC_SET_PAGE_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_SET_PAGE_ENTRY:
 #endif
 		err =
 		    mtrr_add_page(sentry.base, sentry.size, sentry.type, false);
 		break;
 	case MTRRIOC_DEL_PAGE_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_DEL_PAGE_ENTRY:
 #endif
 		err = mtrr_file_del(sentry.base, sentry.size, file, 1);
 		break;
 	case MTRRIOC_KILL_PAGE_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_KILL_PAGE_ENTRY:
 #endif
 		err = mtrr_del_page(-1, sentry.base, sentry.size);
 		break;
 	case MTRRIOC_GET_PAGE_ENTRY:
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_GET_PAGE_ENTRY:
 #endif
 		if (gentry.regnum >= num_var_ranges)
 			return -EINVAL;
 		mtrr_if->get(gentry.regnum, &base, &size, &type);
 		/* Hide entries that would overflow */
 		if (size != (__typeof__(gentry.size))size)
 			gentry.base = gentry.size = gentry.type = 0;
 		else {
 			gentry.base = base;
 			gentry.size = size;
 			gentry.type = type;
 		}
 		break;
 	}

 	if (err)
 		return err;

 	switch (cmd) {
 	case MTRRIOC_GET_ENTRY:
 	case MTRRIOC_GET_PAGE_ENTRY:
 		if (copy_to_user(arg, &gentry, sizeof(gentry)))
 			err = -EFAULT;
 		break;
 #ifdef CONFIG_COMPAT
 	case MTRRIOC32_GET_ENTRY:
 	case MTRRIOC32_GET_PAGE_ENTRY: {
 		struct mtrr_gentry32 __user *g32;

 		g32 = (struct mtrr_gentry32 __user *)__arg;
 		err = put_user(gentry.base, &g32->base);
 		err |= put_user(gentry.size, &g32->size);
 		err |= put_user(gentry.regnum, &g32->regnum);
 		err |= put_user(gentry.type, &g32->type);
 		break;
 	}
 #endif
 	}
 	return err;
 }

 static int mtrr_close(struct inode *ino, struct file *file)
 {
 	unsigned int *fcount = FILE_FCOUNT(file);
 	int i, max;

 	if (fcount != NULL) {
 		max = num_var_ranges;
 		for (i = 0; i < max; ++i) {
 			while (fcount[i] > 0) {
 				mtrr_del(i, 0, 0);
 				--fcount[i];
 			}
 		}
 		kfree(fcount);
 		FILE_FCOUNT(file) = NULL;
 	}
 	return single_release(ino, file);
 }

 static int mtrr_seq_show(struct seq_file *seq, void *offset)
 {
 	char factor;
 	int i, max;
 	mtrr_type type;
 	unsigned long base, size;

 	max = num_var_ranges;
 	for (i = 0; i < max; i++) {
 		mtrr_if->get(i, &base, &size, &type);
 		if (size == 0) {
 			mtrr_usage_table[i] = 0;
 			continue;
 		}
 		if (size < (0x100000 >> PAGE_SHIFT)) {
 			/* less than 1MB */
 			factor = 'K';
 			size <<= PAGE_SHIFT - 10;
 		} else {
 			factor = 'M';
 			size >>= 20 - PAGE_SHIFT;
 		}
 		/* Base can be > 32bit */
 		seq_printf(seq, "reg%02i: base=0x%06lx000 (%5luMB), size=%5lu%cB, count=%d: %s\n",
 			   i, base, base >> (20 - PAGE_SHIFT),
 			   size, factor,
 			   mtrr_usage_table[i], mtrr_attrib_to_str(type));
 	}
 	return 0;
 }

 static int mtrr_open(struct inode *inode, struct file *file)
 {
 	if (!mtrr_if)
 		return -EIO;
 	if (!mtrr_if->get)
 		return -ENXIO;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	return single_open(file, mtrr_seq_show, NULL);
 }

 static const struct proc_ops mtrr_proc_ops = {
 	.proc_open		= mtrr_open,
 	.proc_read		= seq_read,
 	.proc_lseek		= seq_lseek,
 	.proc_write		= mtrr_write,
 	.proc_ioctl		= mtrr_ioctl,
 #ifdef CONFIG_COMPAT
 	.proc_compat_ioctl	= mtrr_ioctl,
 #endif
 	.proc_release		= mtrr_close,
 };

 static int __init mtrr_if_init(void)
 {
 	struct cpuinfo_x86 *c = &boot_cpu_data;

 	if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
 	    (!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
 	    (!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
 	    (!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
 		return -ENODEV;

 	proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_proc_ops);
 	return 0;
 }
 arch_initcall(mtrr_if_init);
 #endif			/*  CONFIG_PROC_FS  */
	// SPDX-License-Identifier: GPL-2.0
	#include <linux/capability.h>
	#include <linux/seq_file.h>
	#include <linux/uaccess.h>
	#include <linux/proc_fs.h>
	#include <linux/ctype.h>
	#include <linux/string.h>
	#include <linux/slab.h>
	#include <linux/init.h>

	#define LINE_SIZE 80

	#include <asm/mtrr.h>

	#include "mtrr.h"

	#define FILE_FCOUNT(f) (((struct seq_file *)((f)->private_data))->private)

	static const char *const mtrr_strings[MTRR_NUM_TYPES] =
	{
	"uncachable", /* 0 */
	"write-combining", /* 1 */
	"?", /* 2 */
	"?", /* 3 */
	"write-through", /* 4 */
	"write-protect", /* 5 */
	"write-back", /* 6 */
	};

	const char *mtrr_attrib_to_str(int x)
	{
	return (x <= 6) ? mtrr_strings[x] : "?";
	}

	#ifdef CONFIG_PROC_FS

	static int
	mtrr_file_add(unsigned long base, unsigned long size,
	unsigned int type, bool increment, struct file *file, int page)
	{
	unsigned int *fcount = FILE_FCOUNT(file);
	int reg, max;

	max = num_var_ranges;
	if (fcount == NULL) {
	fcount = kcalloc(max, sizeof(*fcount), GFP_KERNEL);
	if (!fcount)
	return -ENOMEM;
	FILE_FCOUNT(file) = fcount;
	}
	if (!page) {
	if ((base & (PAGE_SIZE - 1)) \|\| (size & (PAGE_SIZE - 1)))
	return -EINVAL;
	base >>= PAGE_SHIFT;
	size >>= PAGE_SHIFT;
	}
	reg = mtrr_add_page(base, size, type, true);
	if (reg >= 0)
	++fcount[reg];
	return reg;
	}

	static int
	mtrr_file_del(unsigned long base, unsigned long size,
	struct file *file, int page)
	{
	unsigned int *fcount = FILE_FCOUNT(file);
	int reg;

	if (!page) {
	if ((base & (PAGE_SIZE - 1)) \|\| (size & (PAGE_SIZE - 1)))
	return -EINVAL;
	base >>= PAGE_SHIFT;
	size >>= PAGE_SHIFT;
	}
	reg = mtrr_del_page(-1, base, size);
	if (reg < 0)
	return reg;
	if (fcount == NULL)
	return reg;
	if (fcount[reg] < 1)
	return -EINVAL;
	--fcount[reg];
	return reg;
	}

	/*
	* seq_file can seek but we ignore it.
	*
	* Format of control line:
	* "base=%Lx size=%Lx type=%s" or "disable=%d"
	*/
	static ssize_t
	mtrr_write(struct file file, const char __user buf, size_t len, loff_t * ppos)
	{
	int i, err;
	unsigned long reg;
	unsigned long long base, size;
	char *ptr;
	char line[LINE_SIZE];
	int length;
	size_t linelen;

	memset(line, 0, LINE_SIZE);

	len = min_t(size_t, len, LINE_SIZE - 1);
	length = strncpy_from_user(line, buf, len);
	if (length < 0)
	return length;

	linelen = strlen(line);
	ptr = line + linelen - 1;
	if (linelen && *ptr == '\n')
	*ptr = '\0';

	if (!strncmp(line, "disable=", 8)) {
	reg = simple_strtoul(line + 8, &ptr, 0);
	err = mtrr_del_page(reg, 0, 0);
	if (err < 0)
	return err;
	return len;
	}

	if (strncmp(line, "base=", 5))
	return -EINVAL;

	base = simple_strtoull(line + 5, &ptr, 0);
	ptr = skip_spaces(ptr);

	if (strncmp(ptr, "size=", 5))
	return -EINVAL;

	size = simple_strtoull(ptr + 5, &ptr, 0);
	if ((base & 0xfff) \|\| (size & 0xfff))
	return -EINVAL;
	ptr = skip_spaces(ptr);

	if (strncmp(ptr, "type=", 5))
	return -EINVAL;
	ptr = skip_spaces(ptr + 5);

	i = match_string(mtrr_strings, MTRR_NUM_TYPES, ptr);
	if (i < 0)
	return i;

	base >>= PAGE_SHIFT;
	size >>= PAGE_SHIFT;
	err = mtrr_add_page((unsigned long)base, (unsigned long)size, i, true);
	if (err < 0)
	return err;
	return len;
	}

	static long
	mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
	{
	int err = 0;
	mtrr_type type;
	unsigned long base;
	unsigned long size;
	struct mtrr_sentry sentry;
	struct mtrr_gentry gentry;
	void __user arg = (void __user ) __arg;

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

	switch (cmd) {
	case MTRRIOC_ADD_ENTRY:
	case MTRRIOC_SET_ENTRY:
	case MTRRIOC_DEL_ENTRY:
	case MTRRIOC_KILL_ENTRY:
	case MTRRIOC_ADD_PAGE_ENTRY:
	case MTRRIOC_SET_PAGE_ENTRY:
	case MTRRIOC_DEL_PAGE_ENTRY:
	case MTRRIOC_KILL_PAGE_ENTRY:
	if (copy_from_user(&sentry, arg, sizeof(sentry)))
	return -EFAULT;
	break;
	case MTRRIOC_GET_ENTRY:
	case MTRRIOC_GET_PAGE_ENTRY:
	if (copy_from_user(&gentry, arg, sizeof(gentry)))
	return -EFAULT;
	break;
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_ADD_ENTRY:
	case MTRRIOC32_SET_ENTRY:
	case MTRRIOC32_DEL_ENTRY:
	case MTRRIOC32_KILL_ENTRY:
	case MTRRIOC32_ADD_PAGE_ENTRY:
	case MTRRIOC32_SET_PAGE_ENTRY:
	case MTRRIOC32_DEL_PAGE_ENTRY:
	case MTRRIOC32_KILL_PAGE_ENTRY: {
	struct mtrr_sentry32 __user *s32;

	s32 = (struct mtrr_sentry32 __user *)__arg;
	err = get_user(sentry.base, &s32->base);
	err \|= get_user(sentry.size, &s32->size);
	err \|= get_user(sentry.type, &s32->type);
	if (err)
	return err;
	break;
	}
	case MTRRIOC32_GET_ENTRY:
	case MTRRIOC32_GET_PAGE_ENTRY: {
	struct mtrr_gentry32 __user *g32;

	g32 = (struct mtrr_gentry32 __user *)__arg;
	err = get_user(gentry.regnum, &g32->regnum);
	err \|= get_user(gentry.base, &g32->base);
	err \|= get_user(gentry.size, &g32->size);
	err \|= get_user(gentry.type, &g32->type);
	if (err)
	return err;
	break;
	}
	#endif
	}

	switch (cmd) {
	default:
	return -ENOTTY;
	case MTRRIOC_ADD_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_ADD_ENTRY:
	#endif
	err =
	mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
	file, 0);
	break;
	case MTRRIOC_SET_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_SET_ENTRY:
	#endif
	err = mtrr_add(sentry.base, sentry.size, sentry.type, false);
	break;
	case MTRRIOC_DEL_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_DEL_ENTRY:
	#endif
	err = mtrr_file_del(sentry.base, sentry.size, file, 0);
	break;
	case MTRRIOC_KILL_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_KILL_ENTRY:
	#endif
	err = mtrr_del(-1, sentry.base, sentry.size);
	break;
	case MTRRIOC_GET_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_GET_ENTRY:
	#endif
	if (gentry.regnum >= num_var_ranges)
	return -EINVAL;
	mtrr_if->get(gentry.regnum, &base, &size, &type);

	/* Hide entries that go above 4GB */
	if (base + size - 1 >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT))
	\|\| size >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT)))
	gentry.base = gentry.size = gentry.type = 0;
	else {
	gentry.base = base << PAGE_SHIFT;
	gentry.size = size << PAGE_SHIFT;
	gentry.type = type;
	}

	break;
	case MTRRIOC_ADD_PAGE_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_ADD_PAGE_ENTRY:
	#endif
	err =
	mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
	file, 1);
	break;
	case MTRRIOC_SET_PAGE_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_SET_PAGE_ENTRY:
	#endif
	err =
	mtrr_add_page(sentry.base, sentry.size, sentry.type, false);
	break;
	case MTRRIOC_DEL_PAGE_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_DEL_PAGE_ENTRY:
	#endif
	err = mtrr_file_del(sentry.base, sentry.size, file, 1);
	break;
	case MTRRIOC_KILL_PAGE_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_KILL_PAGE_ENTRY:
	#endif
	err = mtrr_del_page(-1, sentry.base, sentry.size);
	break;
	case MTRRIOC_GET_PAGE_ENTRY:
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_GET_PAGE_ENTRY:
	#endif
	if (gentry.regnum >= num_var_ranges)
	return -EINVAL;
	mtrr_if->get(gentry.regnum, &base, &size, &type);
	/* Hide entries that would overflow */
	if (size != (__typeof__(gentry.size))size)
	gentry.base = gentry.size = gentry.type = 0;
	else {
	gentry.base = base;
	gentry.size = size;
	gentry.type = type;
	}
	break;
	}

	if (err)
	return err;

	switch (cmd) {
	case MTRRIOC_GET_ENTRY:
	case MTRRIOC_GET_PAGE_ENTRY:
	if (copy_to_user(arg, &gentry, sizeof(gentry)))
	err = -EFAULT;
	break;
	#ifdef CONFIG_COMPAT
	case MTRRIOC32_GET_ENTRY:
	case MTRRIOC32_GET_PAGE_ENTRY: {
	struct mtrr_gentry32 __user *g32;

	g32 = (struct mtrr_gentry32 __user *)__arg;
	err = put_user(gentry.base, &g32->base);
	err \|= put_user(gentry.size, &g32->size);
	err \|= put_user(gentry.regnum, &g32->regnum);
	err \|= put_user(gentry.type, &g32->type);
	break;
	}
	#endif
	}
	return err;
	}

	static int mtrr_close(struct inode ino, struct file file)
	{
	unsigned int *fcount = FILE_FCOUNT(file);
	int i, max;

	if (fcount != NULL) {
	max = num_var_ranges;
	for (i = 0; i < max; ++i) {
	while (fcount[i] > 0) {
	mtrr_del(i, 0, 0);
	--fcount[i];
	}
	}
	kfree(fcount);
	FILE_FCOUNT(file) = NULL;
	}
	return single_release(ino, file);
	}

	static int mtrr_seq_show(struct seq_file seq, void offset)
	{
	char factor;
	int i, max;
	mtrr_type type;
	unsigned long base, size;

	max = num_var_ranges;
	for (i = 0; i < max; i++) {
	mtrr_if->get(i, &base, &size, &type);
	if (size == 0) {
	mtrr_usage_table[i] = 0;
	continue;
	}
	if (size < (0x100000 >> PAGE_SHIFT)) {
	/* less than 1MB */
	factor = 'K';
	size <<= PAGE_SHIFT - 10;
	} else {
	factor = 'M';
	size >>= 20 - PAGE_SHIFT;
	}
	/* Base can be > 32bit */
	seq_printf(seq, "reg%02i: base=0x%06lx000 (%5luMB), size=%5lu%cB, count=%d: %s\n",
	i, base, base >> (20 - PAGE_SHIFT),
	size, factor,
	mtrr_usage_table[i], mtrr_attrib_to_str(type));
	}
	return 0;
	}

	static int mtrr_open(struct inode inode, struct file file)
	{
	if (!mtrr_if)
	return -EIO;
	if (!mtrr_if->get)
	return -ENXIO;
	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	return single_open(file, mtrr_seq_show, NULL);
	}

	static const struct proc_ops mtrr_proc_ops = {
	.proc_open = mtrr_open,
	.proc_read = seq_read,
	.proc_lseek = seq_lseek,
	.proc_write = mtrr_write,
	.proc_ioctl = mtrr_ioctl,
	#ifdef CONFIG_COMPAT
	.proc_compat_ioctl = mtrr_ioctl,
	#endif
	.proc_release = mtrr_close,
	};

	static int __init mtrr_if_init(void)
	{
	struct cpuinfo_x86 *c = &boot_cpu_data;

	if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
	(!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
	(!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
	(!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
	return -ENODEV;

	proc_create("mtrr", S_IWUSR \| S_IRUGO, NULL, &mtrr_proc_ops);
	return 0;
	}
	arch_initcall(mtrr_if_init);
	#endif /* CONFIG_PROC_FS */