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 14 static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, 15 unsigned long offset, int userbuf, 16 bool encrypted) 17 { 18 void *vaddr; 19 20 if (!csize) 21 return 0; 22 23 if (encrypted) 24 vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE); 25 else 26 vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE); 27 28 if (!vaddr) 29 return -ENOMEM; 30 31 if (userbuf) { 32 if (copy_to_user((void __user *)buf, vaddr + offset, csize)) { 33 iounmap((void __iomem *)vaddr); 34 return -EFAULT; 35 } 36 } else 37 memcpy(buf, vaddr + offset, csize); 38 39 set_iounmap_nonlazy(); 40 iounmap((void __iomem *)vaddr); 41 return csize; 42 } 43 44 /** 45 * copy_oldmem_page - copy one page of memory 46 * @pfn: page frame number to be copied 47 * @buf: target memory address for the copy; this can be in kernel address 48 * space or user address space (see @userbuf) 49 * @csize: number of bytes to copy 50 * @offset: offset in bytes into the page (based on pfn) to begin the copy 51 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 52 * otherwise @buf is in kernel address space, use memcpy(). 53 * 54 * Copy a page from the old kernel's memory. For this page, there is no pte 55 * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic. 56 */ 57 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, 58 unsigned long offset, int userbuf) 59 { 60 return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false); 61 } 62 63 /** 64 * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the 65 * memory with the encryption mask set to accommodate kdump on SME-enabled 66 * machines. 67 */ 68 ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize, 69 unsigned long offset, int userbuf) 70 { 71 return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true); 72 } 73 74 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) 75 { 76 return read_from_oldmem(buf, count, ppos, 0, sev_active()); 77 } 78