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