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Commit c33fa9f5 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

uaccess: add probe_kernel_write() 



add probe_kernel_read() and probe_kernel_write().

Uninlined and restricted to kernel range memory only, as suggested
by Linus.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4b119e21

include/linux/uaccess.h

+22 −0
Original line number Diff line number Diff line
@@ -84,4 +84,26 @@ static inline unsigned long __copy_from_user_nocache(void *to, 
		ret;					\

	})



/*

 * probe_kernel_read(): safely attempt to read from a location

 * @dst: pointer to the buffer that shall take the data

 * @src: address to read from

 * @size: size of the data chunk

 *

 * Safely read from address @src to the buffer at @dst.  If a kernel fault

 * happens, handle that and return -EFAULT.

 */

extern long probe_kernel_read(void *dst, void *src, size_t size);



/*

 * probe_kernel_write(): safely attempt to write to a location

 * @dst: address to write to

 * @src: pointer to the data that shall be written

 * @size: size of the data chunk

 *

 * Safely write to address @dst from the buffer at @src.  If a kernel fault

 * happens, handle that and return -EFAULT.

 */

extern long probe_kernel_write(void *dst, void *src, size_t size);



#endif		/* __LINUX_UACCESS_H__ */

mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \ 
			   vmalloc.o



obj-y			:= bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \

			   page_alloc.o page-writeback.o pdflush.o \

			   maccess.o page_alloc.o page-writeback.o pdflush.o \

			   readahead.o swap.o truncate.o vmscan.o \

			   prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \

			   page_isolation.o $(mmu-y)

mm/maccess.c

0 → 100644
+49 −0
Original line number Diff line number Diff line 
/*

 * Access kernel memory without faulting.

 */

#include <linux/uaccess.h>

#include <linux/module.h>

#include <linux/mm.h>



/**

 * probe_kernel_read(): safely attempt to read from a location

 * @dst: pointer to the buffer that shall take the data

 * @src: address to read from

 * @size: size of the data chunk

 *

 * Safely read from address @src to the buffer at @dst.  If a kernel fault

 * happens, handle that and return -EFAULT.

 */

long probe_kernel_read(void *dst, void *src, size_t size)

{

	long ret;



	pagefault_disable();

	ret = __copy_from_user_inatomic(dst,

			(__force const void __user *)src, size);

	pagefault_enable();



	return ret ? -EFAULT : 0;

}

EXPORT_SYMBOL_GPL(probe_kernel_read);



/**

 * probe_kernel_write(): safely attempt to write to a location

 * @dst: address to write to

 * @src: pointer to the data that shall be written

 * @size: size of the data chunk

 *

 * Safely write to address @dst from the buffer at @src.  If a kernel fault

 * happens, handle that and return -EFAULT.

 */

long probe_kernel_write(void *dst, void *src, size_t size)

{

	long ret;



	pagefault_disable();

	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);

	pagefault_enable();



	return ret ? -EFAULT : 0;

}

EXPORT_SYMBOL_GPL(probe_kernel_write);