/* * Access kernel memory without faulting. */#include <linux/export.h>#include <linux/mm.h>#include <linux/uaccess.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 __weak probe_kernel_read(void *dst, const void *src, size_t size)    __attribute__((alias("__probe_kernel_read"))); long __probe_kernel_read(void *dst, const void *src, size_t size){	long ret;	mm_segment_t old_fs = get_fs(); 	set_fs(KERNEL_DS);	pagefault_disable();	ret = __copy_from_user_inatomic(dst,			(__force const void __user *)src, size);	pagefault_enable();	set_fs(old_fs); 	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 __weak probe_kernel_write(void *dst, const void *src, size_t size)    __attribute__((alias("__probe_kernel_write"))); long __probe_kernel_write(void *dst, const void *src, size_t size){	long ret;	mm_segment_t old_fs = get_fs(); 	set_fs(KERNEL_DS);	pagefault_disable();	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);	pagefault_enable();	set_fs(old_fs); 	return ret ? -EFAULT : 0;}EXPORT_SYMBOL_GPL(probe_kernel_write);