Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  *	kernel/crash_dump.c - Memory preserving reboot related code.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  *	Created by: Simon Horman <horms@verge.net.au>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  *	Original code moved from kernel/crash.c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  *	Original code comment copied from the i386 version of this file
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/errno.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/types.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/crash_dump.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <asm/page.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) #include <linux/uaccess.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)  * copy_oldmem_page - copy one page from "oldmem"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)  * @pfn: page frame number to be copied
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)  * @buf: target memory address for the copy; this can be in kernel address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21)  *	space or user address space (see @userbuf)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22)  * @csize: number of bytes to copy
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)  * @offset: offset in bytes into the page (based on pfn) to begin the copy
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24)  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)  *	otherwise @buf is in kernel address space, use memcpy().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27)  * Copy a page from "oldmem". For this page, there is no pte mapped
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)  * Calling copy_to_user() in atomic context is not desirable. Hence first
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)  * copying the data to a pre-allocated kernel page and then copying to user
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32)  * space in non-atomic context.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) ssize_t
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) copy_oldmem_page(unsigned long pfn, char *buf,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 		size_t csize, unsigned long offset, int userbuf)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 	void  *vaddr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	if (!csize)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 	vaddr = __va(pfn<<PAGE_SHIFT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 	if (userbuf) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 		if (copy_to_user(buf, (vaddr + offset), csize)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 			return -EFAULT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 	} else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 		memcpy(buf, (vaddr + offset), csize);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	return csize;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51)