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/memblock.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 #include <asm/rtas.h> 23 24 #ifdef DEBUG 25 #include <asm/udbg.h> 26 #define DBG(fmt...) udbg_printf(fmt) 27 #else 28 #define DBG(fmt...) 29 #endif 30 31 /* Stores the physical address of elf header of crash image. */ 32 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; 33 34 #ifndef CONFIG_RELOCATABLE 35 void __init reserve_kdump_trampoline(void) 36 { 37 memblock_reserve(0, KDUMP_RESERVE_LIMIT); 38 } 39 40 static void __init create_trampoline(unsigned long addr) 41 { 42 unsigned int *p = (unsigned int *)addr; 43 44 /* The maximum range of a single instruction branch, is the current 45 * instruction's address + (32 MB - 4) bytes. For the trampoline we 46 * need to branch to current address + 32 MB. So we insert a nop at 47 * the trampoline address, then the next instruction (+ 4 bytes) 48 * does a branch to (32 MB - 4). The net effect is that when we 49 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires 50 * two instructions it doesn't require any registers. 51 */ 52 patch_instruction(p, PPC_INST_NOP); 53 patch_branch(++p, addr + PHYSICAL_START, 0); 54 } 55 56 void __init setup_kdump_trampoline(void) 57 { 58 unsigned long i; 59 60 DBG(" -> setup_kdump_trampoline()\n"); 61 62 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { 63 create_trampoline(i); 64 } 65 66 #ifdef CONFIG_PPC_PSERIES 67 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); 68 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); 69 #endif /* CONFIG_PPC_PSERIES */ 70 71 DBG(" <- setup_kdump_trampoline()\n"); 72 } 73 #endif /* CONFIG_RELOCATABLE */ 74 75 /* 76 * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by 77 * is_kdump_kernel() to determine if we are booting after a panic. Hence 78 * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE. 79 */ 80 static int __init parse_elfcorehdr(char *p) 81 { 82 if (p) 83 elfcorehdr_addr = memparse(p, &p); 84 85 return 1; 86 } 87 __setup("elfcorehdr=", parse_elfcorehdr); 88 89 static int __init parse_savemaxmem(char *p) 90 { 91 if (p) 92 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; 93 94 return 1; 95 } 96 __setup("savemaxmem=", parse_savemaxmem); 97 98 99 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, 100 unsigned long offset, int userbuf) 101 { 102 if (userbuf) { 103 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) 104 return -EFAULT; 105 } else 106 memcpy(buf, (vaddr + offset), csize); 107 108 return csize; 109 } 110 111 /** 112 * copy_oldmem_page - copy one page from "oldmem" 113 * @pfn: page frame number to be copied 114 * @buf: target memory address for the copy; this can be in kernel address 115 * space or user address space (see @userbuf) 116 * @csize: number of bytes to copy 117 * @offset: offset in bytes into the page (based on pfn) to begin the copy 118 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 119 * otherwise @buf is in kernel address space, use memcpy(). 120 * 121 * Copy a page from "oldmem". For this page, there is no pte mapped 122 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 123 */ 124 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 125 size_t csize, unsigned long offset, int userbuf) 126 { 127 void *vaddr; 128 129 if (!csize) 130 return 0; 131 132 csize = min_t(size_t, csize, PAGE_SIZE); 133 134 if ((min_low_pfn < pfn) && (pfn < max_pfn)) { 135 vaddr = __va(pfn << PAGE_SHIFT); 136 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 137 } else { 138 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); 139 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 140 iounmap(vaddr); 141 } 142 143 return csize; 144 } 145 146 #ifdef CONFIG_PPC_RTAS 147 /* 148 * The crashkernel region will almost always overlap the RTAS region, so 149 * we have to be careful when shrinking the crashkernel region. 150 */ 151 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end) 152 { 153 unsigned long addr; 154 const u32 *basep, *sizep; 155 unsigned int rtas_start = 0, rtas_end = 0; 156 157 basep = of_get_property(rtas.dev, "linux,rtas-base", NULL); 158 sizep = of_get_property(rtas.dev, "rtas-size", NULL); 159 160 if (basep && sizep) { 161 rtas_start = *basep; 162 rtas_end = *basep + *sizep; 163 } 164 165 for (addr = begin; addr < end; addr += PAGE_SIZE) { 166 /* Does this page overlap with the RTAS region? */ 167 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start)) 168 continue; 169 170 ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT)); 171 init_page_count(pfn_to_page(addr >> PAGE_SHIFT)); 172 free_page((unsigned long)__va(addr)); 173 totalram_pages++; 174 } 175 } 176 #endif 177