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
......@@ -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__ */
......@@ -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)
......
/*
* 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);
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