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Commit f222318e authored by Wu Fengguang's avatar Wu Fengguang Committed by Linus Torvalds
Browse files

/dev/mem: introduce size_inside_page() 



Introduce size_inside_page() to replace duplicate /dev/mem code.

Also apply it to /dev/kmem, whose alignment logic was buggy.

Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Acked-by: default avatarAndi Kleen <ak@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4ea2f43f

drivers/char/mem.c

+19 −41
Original line number Diff line number Diff line
@@ -34,6 +34,19 @@ 
# include <linux/efi.h>

#endif



static inline unsigned long size_inside_page(unsigned long start,

					     unsigned long size)

{

	unsigned long sz;



	if (-start & (PAGE_SIZE - 1))

		sz = -start & (PAGE_SIZE - 1);

	else

		sz = PAGE_SIZE;



	return min_t(unsigned long, sz, size);

}



/*

 * Architectures vary in how they handle caching for addresses

 * outside of main memory.
@@ -141,15 +154,7 @@ static ssize_t read_mem(struct file * file, char __user * buf, 
#endif



	while (count > 0) {

		/*

		 * Handle first page in case it's not aligned

		 */

		if (-p & (PAGE_SIZE - 1))

			sz = -p & (PAGE_SIZE - 1);

		else

			sz = PAGE_SIZE;



		sz = min_t(unsigned long, sz, count);

		sz = size_inside_page(p, count);



		if (!range_is_allowed(p >> PAGE_SHIFT, count))

			return -EPERM;
@@ -208,15 +213,7 @@ static ssize_t write_mem(struct file * file, const char __user * buf, 
#endif



	while (count > 0) {

		/*

		 * Handle first page in case it's not aligned

		 */

		if (-p & (PAGE_SIZE - 1))

			sz = -p & (PAGE_SIZE - 1);

		else

			sz = PAGE_SIZE;



		sz = min_t(unsigned long, sz, count);

		sz = size_inside_page(p, count);



		if (!range_is_allowed(p >> PAGE_SHIFT, sz))

			return -EPERM;
@@ -429,15 +426,7 @@ static ssize_t read_kmem(struct file *file, char __user *buf, 
		}

#endif

		while (low_count > 0) {

			/*

			 * Handle first page in case it's not aligned

			 */

			if (-p & (PAGE_SIZE - 1))

				sz = -p & (PAGE_SIZE - 1);

			else

				sz = PAGE_SIZE;



			sz = min_t(unsigned long, sz, low_count);

			sz = size_inside_page(p, low_count);



			/*

			 * On ia64 if a page has been mapped somewhere as
@@ -461,10 +450,8 @@ static ssize_t read_kmem(struct file *file, char __user *buf, 
		if (!kbuf)

			return -ENOMEM;

		while (count > 0) {

			int len = count;

			int len = size_inside_page(p, count);



			if (len > PAGE_SIZE)

				len = PAGE_SIZE;

			len = vread(kbuf, (char *)p, len);

			if (!len)

				break;
@@ -509,15 +496,8 @@ do_write_kmem(void *p, unsigned long realp, const char __user * buf, 


	while (count > 0) {

		char *ptr;

		/*

		 * Handle first page in case it's not aligned

		 */

		if (-realp & (PAGE_SIZE - 1))

			sz = -realp & (PAGE_SIZE - 1);

		else

			sz = PAGE_SIZE;



		sz = min_t(unsigned long, sz, count);

		sz = size_inside_page(realp, count);



		/*

		 * On ia64 if a page has been mapped somewhere as
@@ -577,10 +557,8 @@ static ssize_t write_kmem(struct file * file, const char __user * buf, 
		if (!kbuf)

			return wrote ? wrote : -ENOMEM;

		while (count > 0) {

			int len = count;

			int len = size_inside_page(p, count);



			if (len > PAGE_SIZE)

				len = PAGE_SIZE;

			written = copy_from_user(kbuf, buf, len);

			if (written) {

				if (wrote + virtr)