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/code-patching.h> 18 #include <asm/kdump.h> 19 #include <asm/prom.h> 20 #include <asm/firmware.h> 21 #include <asm/uaccess.h> 22 23 #ifdef DEBUG 24 #include <asm/udbg.h> 25 #define DBG(fmt...) udbg_printf(fmt) 26 #else 27 #define DBG(fmt...) 28 #endif 29 30 void __init reserve_kdump_trampoline(void) 31 { 32 lmb_reserve(0, KDUMP_RESERVE_LIMIT); 33 } 34 35 static void __init create_trampoline(unsigned long addr) 36 { 37 unsigned int *p = (unsigned int *)addr; 38 39 /* The maximum range of a single instruction branch, is the current 40 * instruction's address + (32 MB - 4) bytes. For the trampoline we 41 * need to branch to current address + 32 MB. So we insert a nop at 42 * the trampoline address, then the next instruction (+ 4 bytes) 43 * does a branch to (32 MB - 4). The net effect is that when we 44 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 45 * two instructions it doesn't require any registers. 46 */ 47 patch_instruction(p, PPC_NOP_INSTR); 48 patch_branch(++p, addr + PHYSICAL_START, 0); 49 } 50 51 void __init setup_kdump_trampoline(void) 52 { 53 unsigned long i; 54 55 DBG(" -> setup_kdump_trampoline()\n"); 56 57 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 58 create_trampoline(i); 59 } 60 61 #ifdef CONFIG_PPC_PSERIES 62 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 63 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 64 #endif /* CONFIG_PPC_PSERIES */ 65 66 DBG(" <- setup_kdump_trampoline()\n"); 67 } 68 69 #ifdef CONFIG_PROC_VMCORE 70 static int __init parse_elfcorehdr(char *p) 71 { 72 if (p) 73 elfcorehdr_addr = memparse(p, &p); 74 75 return 1; 76 } 77 __setup("elfcorehdr=", parse_elfcorehdr); 78 #endif 79 80 static int __init parse_savemaxmem(char *p) 81 { 82 if (p) 83 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 84 85 return 1; 86 } 87 __setup("savemaxmem=", parse_savemaxmem); 88 89 /** 90 * copy_oldmem_page - copy one page from "oldmem" 91 * @pfn: page frame number to be copied 92 * @buf: target memory address for the copy; this can be in kernel address 93 * space or user address space (see @userbuf) 94 * @csize: number of bytes to copy 95 * @offset: offset in bytes into the page (based on pfn) to begin the copy 96 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 97 * otherwise @buf is in kernel address space, use memcpy(). 98 * 99 * Copy a page from "oldmem". For this page, there is no pte mapped 100 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 101 */ 102 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 103 size_t csize, unsigned long offset, int userbuf) 104 { 105 void *vaddr; 106 107 if (!csize) 108 return 0; 109 110 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 111 112 if (userbuf) { 113 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) { 114 iounmap(vaddr); 115 return -EFAULT; 116 } 117 } else 118 memcpy(buf, (vaddr + offset), csize); 119 120 iounmap(vaddr); 121 return csize; 122 } 123