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 <linux/lmb.h> 17 #include <asm/kdump.h> 18 #include <asm/prom.h> 19 #include <asm/firmware.h> 20 #include <asm/uaccess.h> 21 22 #ifdef DEBUG 23 #include <asm/udbg.h> 24 #define DBG(fmt...) udbg_printf(fmt) 25 #else 26 #define DBG(fmt...) 27 #endif 28 29 void __init reserve_kdump_trampoline(void) 30 { 31 lmb_reserve(0, KDUMP_RESERVE_LIMIT); 32 } 33 34 static void __init create_trampoline(unsigned long addr) 35 { 36 /* The maximum range of a single instruction branch, is the current 37 * instruction's address + (32 MB - 4) bytes. For the trampoline we 38 * need to branch to current address + 32 MB. So we insert a nop at 39 * the trampoline address, then the next instruction (+ 4 bytes) 40 * does a branch to (32 MB - 4). The net effect is that when we 41 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 42 * two instructions it doesn't require any registers. 43 */ 44 create_instruction(addr, 0x60000000); /* nop */ 45 create_branch(addr + 4, addr + PHYSICAL_START, 0); 46 } 47 48 void __init setup_kdump_trampoline(void) 49 { 50 unsigned long i; 51 52 DBG(" -> setup_kdump_trampoline()\n"); 53 54 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 55 create_trampoline(i); 56 } 57 58 #ifdef CONFIG_PPC_PSERIES 59 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 60 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 61 #endif /* CONFIG_PPC_PSERIES */ 62 63 DBG(" <- setup_kdump_trampoline()\n"); 64 } 65 66 #ifdef CONFIG_PROC_VMCORE 67 static int __init parse_elfcorehdr(char *p) 68 { 69 if (p) 70 elfcorehdr_addr = memparse(p, &p); 71 72 return 1; 73 } 74 __setup("elfcorehdr=", parse_elfcorehdr); 75 #endif 76 77 static int __init parse_savemaxmem(char *p) 78 { 79 if (p) 80 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 81 82 return 1; 83 } 84 __setup("savemaxmem=", parse_savemaxmem); 85 86 /** 87 * copy_oldmem_page - copy one page from "oldmem" 88 * @pfn: page frame number to be copied 89 * @buf: target memory address for the copy; this can be in kernel address 90 * space or user address space (see @userbuf) 91 * @csize: number of bytes to copy 92 * @offset: offset in bytes into the page (based on pfn) to begin the copy 93 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 94 * otherwise @buf is in kernel address space, use memcpy(). 95 * 96 * Copy a page from "oldmem". For this page, there is no pte mapped 97 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 98 */ 99 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 100 size_t csize, unsigned long offset, int userbuf) 101 { 102 void *vaddr; 103 104 if (!csize) 105 return 0; 106 107 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 108 109 if (userbuf) { 110 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) { 111 iounmap(vaddr); 112 return -EFAULT; 113 } 114 } else 115 memcpy(buf, (vaddr + offset), csize); 116 117 iounmap(vaddr); 118 return csize; 119 } 120