| Eric W. Biederman | 5033cba | 2005-06-25 14:57:56 -0700 | [diff] [blame] | 1 | /* |
| 2 | * relocate_kernel.S - put the kernel image in place to boot |
| 3 | * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com> |
| 4 | * |
| 5 | * This source code is licensed under the GNU General Public License, |
| 6 | * Version 2. See the file COPYING for more details. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/linkage.h> |
| 10 | |
| 11 | /* |
| 12 | * Must be relocatable PIC code callable as a C function, that once |
| 13 | * it starts can not use the previous processes stack. |
| 14 | */ |
| 15 | .globl relocate_new_kernel |
| 16 | relocate_new_kernel: |
| 17 | /* read the arguments and say goodbye to the stack */ |
| 18 | movl 4(%esp), %ebx /* page_list */ |
| 19 | movl 8(%esp), %ebp /* reboot_code_buffer */ |
| 20 | movl 12(%esp), %edx /* start address */ |
| 21 | movl 16(%esp), %ecx /* cpu_has_pae */ |
| 22 | |
| 23 | /* zero out flags, and disable interrupts */ |
| 24 | pushl $0 |
| 25 | popfl |
| 26 | |
| 27 | /* set a new stack at the bottom of our page... */ |
| 28 | lea 4096(%ebp), %esp |
| 29 | |
| 30 | /* store the parameters back on the stack */ |
| 31 | pushl %edx /* store the start address */ |
| 32 | |
| 33 | /* Set cr0 to a known state: |
| 34 | * 31 0 == Paging disabled |
| 35 | * 18 0 == Alignment check disabled |
| 36 | * 16 0 == Write protect disabled |
| 37 | * 3 0 == No task switch |
| 38 | * 2 0 == Don't do FP software emulation. |
| 39 | * 0 1 == Proctected mode enabled |
| 40 | */ |
| 41 | movl %cr0, %eax |
| 42 | andl $~((1<<31)|(1<<18)|(1<<16)|(1<<3)|(1<<2)), %eax |
| 43 | orl $(1<<0), %eax |
| 44 | movl %eax, %cr0 |
| 45 | |
| 46 | /* clear cr4 if applicable */ |
| 47 | testl %ecx, %ecx |
| 48 | jz 1f |
| 49 | /* Set cr4 to a known state: |
| 50 | * Setting everything to zero seems safe. |
| 51 | */ |
| 52 | movl %cr4, %eax |
| 53 | andl $0, %eax |
| 54 | movl %eax, %cr4 |
| 55 | |
| 56 | jmp 1f |
| 57 | 1: |
| 58 | |
| 59 | /* Flush the TLB (needed?) */ |
| 60 | xorl %eax, %eax |
| 61 | movl %eax, %cr3 |
| 62 | |
| 63 | /* Do the copies */ |
| 64 | movl %ebx, %ecx |
| 65 | jmp 1f |
| 66 | |
| 67 | 0: /* top, read another word from the indirection page */ |
| 68 | movl (%ebx), %ecx |
| 69 | addl $4, %ebx |
| 70 | 1: |
| 71 | testl $0x1, %ecx /* is it a destination page */ |
| 72 | jz 2f |
| 73 | movl %ecx, %edi |
| 74 | andl $0xfffff000, %edi |
| 75 | jmp 0b |
| 76 | 2: |
| 77 | testl $0x2, %ecx /* is it an indirection page */ |
| 78 | jz 2f |
| 79 | movl %ecx, %ebx |
| 80 | andl $0xfffff000, %ebx |
| 81 | jmp 0b |
| 82 | 2: |
| 83 | testl $0x4, %ecx /* is it the done indicator */ |
| 84 | jz 2f |
| 85 | jmp 3f |
| 86 | 2: |
| 87 | testl $0x8, %ecx /* is it the source indicator */ |
| 88 | jz 0b /* Ignore it otherwise */ |
| 89 | movl %ecx, %esi /* For every source page do a copy */ |
| 90 | andl $0xfffff000, %esi |
| 91 | |
| 92 | movl $1024, %ecx |
| 93 | rep ; movsl |
| 94 | jmp 0b |
| 95 | |
| 96 | 3: |
| 97 | |
| 98 | /* To be certain of avoiding problems with self-modifying code |
| 99 | * I need to execute a serializing instruction here. |
| 100 | * So I flush the TLB, it's handy, and not processor dependent. |
| 101 | */ |
| 102 | xorl %eax, %eax |
| 103 | movl %eax, %cr3 |
| 104 | |
| 105 | /* set all of the registers to known values */ |
| 106 | /* leave %esp alone */ |
| 107 | |
| 108 | xorl %eax, %eax |
| 109 | xorl %ebx, %ebx |
| 110 | xorl %ecx, %ecx |
| 111 | xorl %edx, %edx |
| 112 | xorl %esi, %esi |
| 113 | xorl %edi, %edi |
| 114 | xorl %ebp, %ebp |
| 115 | ret |
| 116 | relocate_new_kernel_end: |
| 117 | |
| 118 | .globl relocate_new_kernel_size |
| 119 | relocate_new_kernel_size: |
| 120 | .long relocate_new_kernel_end - relocate_new_kernel |