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 /* Stores the physical address of elf header of crash image. */ 31 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; 32 33 void __init reserve_kdump_trampoline(void) 34 { 35 lmb_reserve(0, KDUMP_RESERVE_LIMIT); 36 } 37 38 static void __init create_trampoline(unsigned long addr) 39 { 40 unsigned int *p = (unsigned int *)addr; 41 42 /* The maximum range of a single instruction branch, is the current 43 * instruction's address + (32 MB - 4) bytes. For the trampoline we 44 * need to branch to current address + 32 MB. So we insert a nop at 45 * the trampoline address, then the next instruction (+ 4 bytes) 46 * does a branch to (32 MB - 4). The net effect is that when we 47 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 48 * two instructions it doesn't require any registers. 49 */ 50 patch_instruction(p, PPC_NOP_INSTR); 51 patch_branch(++p, addr + PHYSICAL_START, 0); 52 } 53 54 void __init setup_kdump_trampoline(void) 55 { 56 unsigned long i; 57 58 DBG(" -> setup_kdump_trampoline()\n"); 59 60 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 61 create_trampoline(i); 62 } 63 64 #ifdef CONFIG_PPC_PSERIES 65 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 66 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 67 #endif /* CONFIG_PPC_PSERIES */ 68 69 DBG(" <- setup_kdump_trampoline()\n"); 70 } 71 72 /* 73 * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by 74 * is_kdump_kernel() to determine if we are booting after a panic. Hence 75 * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE. 76 */ 77 static int __init parse_elfcorehdr(char *p) 78 { 79 if (p) 80 elfcorehdr_addr = memparse(p, &p); 81 82 return 1; 83 } 84 __setup("elfcorehdr=", parse_elfcorehdr); 85 86 static int __init parse_savemaxmem(char *p) 87 { 88 if (p) 89 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 90 91 return 1; 92 } 93 __setup("savemaxmem=", parse_savemaxmem); 94 95 96 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, 97 unsigned long offset, int userbuf) 98 { 99 if (userbuf) { 100 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) 101 return -EFAULT; 102 } else 103 memcpy(buf, (vaddr + offset), csize); 104 105 return csize; 106 } 107 108 /** 109 * copy_oldmem_page - copy one page from "oldmem" 110 * @pfn: page frame number to be copied 111 * @buf: target memory address for the copy; this can be in kernel address 112 * space or user address space (see @userbuf) 113 * @csize: number of bytes to copy 114 * @offset: offset in bytes into the page (based on pfn) to begin the copy 115 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 116 * otherwise @buf is in kernel address space, use memcpy(). 117 * 118 * Copy a page from "oldmem". For this page, there is no pte mapped 119 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 120 */ 121 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 122 size_t csize, unsigned long offset, int userbuf) 123 { 124 void *vaddr; 125 126 if (!csize) 127 return 0; 128 129 csize = min(csize, PAGE_SIZE); 130 131 if (pfn < max_pfn) { 132 vaddr = __va(pfn << PAGE_SHIFT); 133 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 134 } else { 135 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 136 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 137 iounmap(vaddr); 138 } 139 140 return csize; 141 } 142