1 /* 2 * Routines for doing kexec-based kdump. 3 * 4 * Copyright (C) 2005, IBM Corp. 5 * 6 * Created by: Michael Ellerman 7 * 8 * This source code is licensed under the GNU General Public License, 9 * Version 2. See the file COPYING for more details. 10 */ 11 12 #undef DEBUG 13 14 #include <linux/crash_dump.h> 15 #include <linux/bootmem.h> 16 #include <asm/kdump.h> 17 #include <asm/lmb.h> 18 #include <asm/firmware.h> 19 #include <asm/uaccess.h> 20 21 #ifdef DEBUG 22 #include <asm/udbg.h> 23 #define DBG(fmt...) udbg_printf(fmt) 24 #else 25 #define DBG(fmt...) 26 #endif 27 28 static void __init create_trampoline(unsigned long addr) 29 { 30 /* The maximum range of a single instruction branch, is the current 31 * instruction's address + (32 MB - 4) bytes. For the trampoline we 32 * need to branch to current address + 32 MB. So we insert a nop at 33 * the trampoline address, then the next instruction (+ 4 bytes) 34 * does a branch to (32 MB - 4). The net effect is that when we 35 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 36 * two instructions it doesn't require any registers. 37 */ 38 create_instruction(addr, 0x60000000); /* nop */ 39 create_branch(addr + 4, addr + PHYSICAL_START, 0); 40 } 41 42 void __init kdump_setup(void) 43 { 44 unsigned long i; 45 46 DBG(" -> kdump_setup()\n"); 47 48 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 49 create_trampoline(i); 50 } 51 52 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 53 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 54 55 DBG(" <- kdump_setup()\n"); 56 } 57 58 static int __init parse_elfcorehdr(char *p) 59 { 60 if (p) 61 elfcorehdr_addr = memparse(p, &p); 62 63 return 0; 64 } 65 __setup("elfcorehdr=", parse_elfcorehdr); 66 67 static int __init parse_savemaxmem(char *p) 68 { 69 if (p) 70 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 71 72 return 0; 73 } 74 __setup("savemaxmem=", parse_savemaxmem); 75 76 /* 77 * copy_oldmem_page - copy one page from "oldmem" 78 * @pfn: page frame number to be copied 79 * @buf: target memory address for the copy; this can be in kernel address 80 * space or user address space (see @userbuf) 81 * @csize: number of bytes to copy 82 * @offset: offset in bytes into the page (based on pfn) to begin the copy 83 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 84 * otherwise @buf is in kernel address space, use memcpy(). 85 * 86 * Copy a page from "oldmem". For this page, there is no pte mapped 87 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 88 */ 89 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 90 size_t csize, unsigned long offset, int userbuf) 91 { 92 void *vaddr; 93 94 if (!csize) 95 return 0; 96 97 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 98 99 if (userbuf) { 100 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) { 101 iounmap(vaddr); 102 return -EFAULT; 103 } 104 } else 105 memcpy(buf, (vaddr + offset), csize); 106 107 iounmap(vaddr); 108 return csize; 109 } 110