1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Memory preserving reboot related code. 4 * 5 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) 6 * Copyright (C) IBM Corporation, 2004. All rights reserved 7 */ 8 9 #include <linux/errno.h> 10 #include <linux/crash_dump.h> 11 #include <linux/uaccess.h> 12 #include <linux/io.h> 13 #include <linux/cc_platform.h> 14 15 static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, 16 unsigned long offset, int userbuf, 17 bool encrypted) 18 { 19 void *vaddr; 20 21 if (!csize) 22 return 0; 23 24 if (encrypted) 25 vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE); 26 else 27 vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE); 28 29 if (!vaddr) 30 return -ENOMEM; 31 32 if (userbuf) { 33 if (copy_to_user((void __user *)buf, vaddr + offset, csize)) { 34 iounmap((void __iomem *)vaddr); 35 return -EFAULT; 36 } 37 } else 38 memcpy(buf, vaddr + offset, csize); 39 40 set_iounmap_nonlazy(); 41 iounmap((void __iomem *)vaddr); 42 return csize; 43 } 44 45 /** 46 * copy_oldmem_page - copy one page of memory 47 * @pfn: page frame number to be copied 48 * @buf: target memory address for the copy; this can be in kernel address 49 * space or user address space (see @userbuf) 50 * @csize: number of bytes to copy 51 * @offset: offset in bytes into the page (based on pfn) to begin the copy 52 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 53 * otherwise @buf is in kernel address space, use memcpy(). 54 * 55 * Copy a page from the old kernel's memory. For this page, there is no pte 56 * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic. 57 */ 58 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, 59 unsigned long offset, int userbuf) 60 { 61 return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false); 62 } 63 64 /** 65 * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the 66 * memory with the encryption mask set to accommodate kdump on SME-enabled 67 * machines. 68 */ 69 ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize, 70 unsigned long offset, int userbuf) 71 { 72 return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true); 73 } 74 75 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) 76 { 77 return read_from_oldmem(buf, count, ppos, 0, 78 cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)); 79 } 80