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 #ifndef CONFIG_RELOCATABLE 34 void __init reserve_kdump_trampoline(void) 35 { 36 lmb_reserve(0, KDUMP_RESERVE_LIMIT); 37 } 38 39 static void __init create_trampoline(unsigned long addr) 40 { 41 unsigned int *p = (unsigned int *)addr; 42 43 /* The maximum range of a single instruction branch, is the current 44 * instruction's address + (32 MB - 4) bytes. For the trampoline we 45 * need to branch to current address + 32 MB. So we insert a nop at 46 * the trampoline address, then the next instruction (+ 4 bytes) 47 * does a branch to (32 MB - 4). The net effect is that when we 48 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 49 * two instructions it doesn't require any registers. 50 */ 51 patch_instruction(p, PPC_INST_NOP); 52 patch_branch(++p, addr + PHYSICAL_START, 0); 53 } 54 55 void __init setup_kdump_trampoline(void) 56 { 57 unsigned long i; 58 59 DBG(" -> setup_kdump_trampoline()\n"); 60 61 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 62 create_trampoline(i); 63 } 64 65 #ifdef CONFIG_PPC_PSERIES 66 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 67 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 68 #endif /* CONFIG_PPC_PSERIES */ 69 70 DBG(" <- setup_kdump_trampoline()\n"); 71 } 72 #endif /* CONFIG_RELOCATABLE */ 73 74 /* 75 * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by 76 * is_kdump_kernel() to determine if we are booting after a panic. Hence 77 * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE. 78 */ 79 static int __init parse_elfcorehdr(char *p) 80 { 81 if (p) 82 elfcorehdr_addr = memparse(p, &p); 83 84 return 1; 85 } 86 __setup("elfcorehdr=", parse_elfcorehdr); 87 88 static int __init parse_savemaxmem(char *p) 89 { 90 if (p) 91 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 92 93 return 1; 94 } 95 __setup("savemaxmem=", parse_savemaxmem); 96 97 98 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, 99 unsigned long offset, int userbuf) 100 { 101 if (userbuf) { 102 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) 103 return -EFAULT; 104 } else 105 memcpy(buf, (vaddr + offset), csize); 106 107 return csize; 108 } 109 110 /** 111 * copy_oldmem_page - copy one page from "oldmem" 112 * @pfn: page frame number to be copied 113 * @buf: target memory address for the copy; this can be in kernel address 114 * space or user address space (see @userbuf) 115 * @csize: number of bytes to copy 116 * @offset: offset in bytes into the page (based on pfn) to begin the copy 117 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 118 * otherwise @buf is in kernel address space, use memcpy(). 119 * 120 * Copy a page from "oldmem". For this page, there is no pte mapped 121 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 122 */ 123 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 124 size_t csize, unsigned long offset, int userbuf) 125 { 126 void *vaddr; 127 128 if (!csize) 129 return 0; 130 131 csize = min(csize, PAGE_SIZE); 132 133 if (pfn < max_pfn) { 134 vaddr = __va(pfn << PAGE_SHIFT); 135 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 136 } else { 137 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 138 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 139 iounmap(vaddr); 140 } 141 142 return csize; 143 } 144