| 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/kdump.h> |
| 18 | #include <asm/prom.h> |
| 19 | #include <asm/firmware.h> |
| 20 | #include <asm/uaccess.h> |
| 21 | |
| 22 | #ifdef DEBUG |
| 23 | #include <asm/udbg.h> |
| 24 | #define DBG(fmt...) udbg_printf(fmt) |
| 25 | #else |
| 26 | #define DBG(fmt...) |
| 27 | #endif |
| 28 | |
| 29 | void __init reserve_kdump_trampoline(void) |
| 30 | { |
| 31 | lmb_reserve(0, KDUMP_RESERVE_LIMIT); |
| 32 | } |
| 33 | |
| 34 | static void __init create_trampoline(unsigned long addr) |
| 35 | { |
| 36 | /* The maximum range of a single instruction branch, is the current |
| 37 | * instruction's address + (32 MB - 4) bytes. For the trampoline we |
| 38 | * need to branch to current address + 32 MB. So we insert a nop at |
| 39 | * the trampoline address, then the next instruction (+ 4 bytes) |
| 40 | * does a branch to (32 MB - 4). The net effect is that when we |
| 41 | * branch to "addr" we jump to ("addr" + 32 MB). Although it requires |
| 42 | * two instructions it doesn't require any registers. |
| 43 | */ |
| 44 | create_instruction(addr, 0x60000000); /* nop */ |
| 45 | create_branch(addr + 4, addr + PHYSICAL_START, 0); |
| 46 | } |
| 47 | |
| 48 | void __init setup_kdump_trampoline(void) |
| 49 | { |
| 50 | unsigned long i; |
| 51 | |
| 52 | DBG(" -> setup_kdump_trampoline()\n"); |
| 53 | |
| 54 | for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) { |
| 55 | create_trampoline(i); |
| 56 | } |
| 57 | |
| 58 | #ifdef CONFIG_PPC_PSERIES |
| 59 | create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START); |
| 60 | create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START); |
| 61 | #endif /* CONFIG_PPC_PSERIES */ |
| 62 | |
| 63 | DBG(" <- setup_kdump_trampoline()\n"); |
| 64 | } |
| 65 | |
| 66 | #ifdef CONFIG_PROC_VMCORE |
| 67 | static int __init parse_elfcorehdr(char *p) |
| 68 | { |
| 69 | if (p) |
| 70 | elfcorehdr_addr = memparse(p, &p); |
| 71 | |
| 72 | return 1; |
| 73 | } |
| 74 | __setup("elfcorehdr=", parse_elfcorehdr); |
| 75 | #endif |
| 76 | |
| 77 | static int __init parse_savemaxmem(char *p) |
| 78 | { |
| 79 | if (p) |
| 80 | saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; |
| 81 | |
| 82 | return 1; |
| 83 | } |
| 84 | __setup("savemaxmem=", parse_savemaxmem); |
| 85 | |
| 86 | /** |
| 87 | * copy_oldmem_page - copy one page from "oldmem" |
| 88 | * @pfn: page frame number to be copied |
| 89 | * @buf: target memory address for the copy; this can be in kernel address |
| 90 | * space or user address space (see @userbuf) |
| 91 | * @csize: number of bytes to copy |
| 92 | * @offset: offset in bytes into the page (based on pfn) to begin the copy |
| 93 | * @userbuf: if set, @buf is in user address space, use copy_to_user(), |
| 94 | * otherwise @buf is in kernel address space, use memcpy(). |
| 95 | * |
| 96 | * Copy a page from "oldmem". For this page, there is no pte mapped |
| 97 | * in the current kernel. We stitch up a pte, similar to kmap_atomic. |
| 98 | */ |
| 99 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, |
| 100 | size_t csize, unsigned long offset, int userbuf) |
| 101 | { |
| 102 | void *vaddr; |
| 103 | |
| 104 | if (!csize) |
| 105 | return 0; |
| 106 | |
| 107 | vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); |
| 108 | |
| 109 | if (userbuf) { |
| 110 | if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) { |
| 111 | iounmap(vaddr); |
| 112 | return -EFAULT; |
| 113 | } |
| 114 | } else |
| 115 | memcpy(buf, (vaddr + offset), csize); |
| 116 | |
| 117 | iounmap(vaddr); |
| 118 | return csize; |
| 119 | } |