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 28void reserve_kdump_trampoline(void) 29{ 30 lmb_reserve(0, KDUMP_RESERVE_LIMIT); 31} 32 33static void __init create_trampoline(unsigned long addr) 34{ 35 /* The maximum range of a single instruction branch, is the current 36 * instruction's address + (32 MB - 4) bytes. For the trampoline we 37 * need to branch to current address + 32 MB. So we insert a nop at 38 * the trampoline address, then the next instruction (+ 4 bytes) 39 * does a branch to (32 MB - 4). The net effect is that when we 40 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 41 * two instructions it doesn't require any registers. 42 */ 43 create_instruction(addr, 0x60000000); /* nop */ 44 create_branch(addr + 4, addr + PHYSICAL_START, 0); 45} 46 47void __init setup_kdump_trampoline(void) 48{ 49 unsigned long i; 50 51 DBG(" -> setup_kdump_trampoline()\n"); 52 53 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 54 create_trampoline(i); 55 } 56 57 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 58 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 59 60 DBG(" <- setup_kdump_trampoline()\n"); 61} 62 63#ifdef CONFIG_PROC_VMCORE 64static int __init parse_elfcorehdr(char *p) 65{ 66 if (p) 67 elfcorehdr_addr = memparse(p, &p); 68 69 return 1; 70} 71__setup("elfcorehdr=", parse_elfcorehdr); 72#endif 73 74static int __init parse_savemaxmem(char *p) 75{ 76 if (p) 77 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 78 79 return 1; 80} 81__setup("savemaxmem=", parse_savemaxmem); 82 83/** 84 * copy_oldmem_page - copy one page from "oldmem" 85 * @pfn: page frame number to be copied 86 * @buf: target memory address for the copy; this can be in kernel address 87 * space or user address space (see @userbuf) 88 * @csize: number of bytes to copy 89 * @offset: offset in bytes into the page (based on pfn) to begin the copy 90 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 91 * otherwise @buf is in kernel address space, use memcpy(). 92 * 93 * Copy a page from "oldmem". For this page, there is no pte mapped 94 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 95 */ 96ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 97 size_t csize, unsigned long offset, int userbuf) 98{ 99 void *vaddr; 100 101 if (!csize) 102 return 0; 103 104 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 105 106 if (userbuf) { 107 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) { 108 iounmap(vaddr); 109 return -EFAULT; 110 } 111 } else 112 memcpy(buf, (vaddr + offset), csize); 113 114 iounmap(vaddr); 115 return csize; 116} 117