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Linux/arch/x86/kernel/relocate_kernel_32.S

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  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 #include <asm/page_types.h>
 11 #include <asm/kexec.h>
 12 #include <asm/processor-flags.h>
 13 
 14 /*
 15  * Must be relocatable PIC code callable as a C function
 16  */
 17 
 18 #define PTR(x) (x << 2)
 19 
 20 /*
 21  * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
 22  * ~ control_page + PAGE_SIZE are used as data storage and stack for
 23  * jumping back
 24  */
 25 #define DATA(offset)            (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
 26 
 27 /* Minimal CPU state */
 28 #define ESP                     DATA(0x0)
 29 #define CR0                     DATA(0x4)
 30 #define CR3                     DATA(0x8)
 31 #define CR4                     DATA(0xc)
 32 
 33 /* other data */
 34 #define CP_VA_CONTROL_PAGE      DATA(0x10)
 35 #define CP_PA_PGD               DATA(0x14)
 36 #define CP_PA_SWAP_PAGE         DATA(0x18)
 37 #define CP_PA_BACKUP_PAGES_MAP  DATA(0x1c)
 38 
 39         .text
 40         .globl relocate_kernel
 41 relocate_kernel:
 42         /* Save the CPU context, used for jumping back */
 43 
 44         pushl   %ebx
 45         pushl   %esi
 46         pushl   %edi
 47         pushl   %ebp
 48         pushf
 49 
 50         movl    20+8(%esp), %ebp /* list of pages */
 51         movl    PTR(VA_CONTROL_PAGE)(%ebp), %edi
 52         movl    %esp, ESP(%edi)
 53         movl    %cr0, %eax
 54         movl    %eax, CR0(%edi)
 55         movl    %cr3, %eax
 56         movl    %eax, CR3(%edi)
 57         movl    %cr4, %eax
 58         movl    %eax, CR4(%edi)
 59 
 60         /* read the arguments and say goodbye to the stack */
 61         movl  20+4(%esp), %ebx /* page_list */
 62         movl  20+8(%esp), %ebp /* list of pages */
 63         movl  20+12(%esp), %edx /* start address */
 64         movl  20+16(%esp), %ecx /* cpu_has_pae */
 65         movl  20+20(%esp), %esi /* preserve_context */
 66 
 67         /* zero out flags, and disable interrupts */
 68         pushl $0
 69         popfl
 70 
 71         /* save some information for jumping back */
 72         movl    PTR(VA_CONTROL_PAGE)(%ebp), %edi
 73         movl    %edi, CP_VA_CONTROL_PAGE(%edi)
 74         movl    PTR(PA_PGD)(%ebp), %eax
 75         movl    %eax, CP_PA_PGD(%edi)
 76         movl    PTR(PA_SWAP_PAGE)(%ebp), %eax
 77         movl    %eax, CP_PA_SWAP_PAGE(%edi)
 78         movl    %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
 79 
 80         /*
 81          * get physical address of control page now
 82          * this is impossible after page table switch
 83          */
 84         movl    PTR(PA_CONTROL_PAGE)(%ebp), %edi
 85 
 86         /* switch to new set of page tables */
 87         movl    PTR(PA_PGD)(%ebp), %eax
 88         movl    %eax, %cr3
 89 
 90         /* setup a new stack at the end of the physical control page */
 91         lea     PAGE_SIZE(%edi), %esp
 92 
 93         /* jump to identity mapped page */
 94         movl    %edi, %eax
 95         addl    $(identity_mapped - relocate_kernel), %eax
 96         pushl   %eax
 97         ret
 98 
 99 identity_mapped:
100         /* set return address to 0 if not preserving context */
101         pushl   $0
102         /* store the start address on the stack */
103         pushl   %edx
104 
105         /*
106          * Set cr0 to a known state:
107          *  - Paging disabled
108          *  - Alignment check disabled
109          *  - Write protect disabled
110          *  - No task switch
111          *  - Don't do FP software emulation.
112          *  - Proctected mode enabled
113          */
114         movl    %cr0, %eax
115         andl    $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax
116         orl     $(X86_CR0_PE), %eax
117         movl    %eax, %cr0
118 
119         /* clear cr4 if applicable */
120         testl   %ecx, %ecx
121         jz      1f
122         /*
123          * Set cr4 to a known state:
124          * Setting everything to zero seems safe.
125          */
126         xorl    %eax, %eax
127         movl    %eax, %cr4
128 
129         jmp 1f
130 1:
131 
132         /* Flush the TLB (needed?) */
133         xorl    %eax, %eax
134         movl    %eax, %cr3
135 
136         movl    CP_PA_SWAP_PAGE(%edi), %eax
137         pushl   %eax
138         pushl   %ebx
139         call    swap_pages
140         addl    $8, %esp
141 
142         /*
143          * To be certain of avoiding problems with self-modifying code
144          * I need to execute a serializing instruction here.
145          * So I flush the TLB, it's handy, and not processor dependent.
146          */
147         xorl    %eax, %eax
148         movl    %eax, %cr3
149 
150         /*
151          * set all of the registers to known values
152          * leave %esp alone
153          */
154 
155         testl   %esi, %esi
156         jnz 1f
157         xorl    %edi, %edi
158         xorl    %eax, %eax
159         xorl    %ebx, %ebx
160         xorl    %ecx, %ecx
161         xorl    %edx, %edx
162         xorl    %esi, %esi
163         xorl    %ebp, %ebp
164         ret
165 1:
166         popl    %edx
167         movl    CP_PA_SWAP_PAGE(%edi), %esp
168         addl    $PAGE_SIZE, %esp
169 2:
170         call    *%edx
171 
172         /* get the re-entry point of the peer system */
173         movl    0(%esp), %ebp
174         call    1f
175 1:
176         popl    %ebx
177         subl    $(1b - relocate_kernel), %ebx
178         movl    CP_VA_CONTROL_PAGE(%ebx), %edi
179         lea     PAGE_SIZE(%ebx), %esp
180         movl    CP_PA_SWAP_PAGE(%ebx), %eax
181         movl    CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
182         pushl   %eax
183         pushl   %edx
184         call    swap_pages
185         addl    $8, %esp
186         movl    CP_PA_PGD(%ebx), %eax
187         movl    %eax, %cr3
188         movl    %cr0, %eax
189         orl     $X86_CR0_PG, %eax
190         movl    %eax, %cr0
191         lea     PAGE_SIZE(%edi), %esp
192         movl    %edi, %eax
193         addl    $(virtual_mapped - relocate_kernel), %eax
194         pushl   %eax
195         ret
196 
197 virtual_mapped:
198         movl    CR4(%edi), %eax
199         movl    %eax, %cr4
200         movl    CR3(%edi), %eax
201         movl    %eax, %cr3
202         movl    CR0(%edi), %eax
203         movl    %eax, %cr0
204         movl    ESP(%edi), %esp
205         movl    %ebp, %eax
206 
207         popf
208         popl    %ebp
209         popl    %edi
210         popl    %esi
211         popl    %ebx
212         ret
213 
214         /* Do the copies */
215 swap_pages:
216         movl    8(%esp), %edx
217         movl    4(%esp), %ecx
218         pushl   %ebp
219         pushl   %ebx
220         pushl   %edi
221         pushl   %esi
222         movl    %ecx, %ebx
223         jmp     1f
224 
225 0:      /* top, read another word from the indirection page */
226         movl    (%ebx), %ecx
227         addl    $4, %ebx
228 1:
229         testb   $0x1, %cl     /* is it a destination page */
230         jz      2f
231         movl    %ecx,   %edi
232         andl    $0xfffff000, %edi
233         jmp     0b
234 2:
235         testb   $0x2, %cl    /* is it an indirection page */
236         jz      2f
237         movl    %ecx,   %ebx
238         andl    $0xfffff000, %ebx
239         jmp     0b
240 2:
241         testb   $0x4, %cl    /* is it the done indicator */
242         jz      2f
243         jmp     3f
244 2:
245         testb   $0x8, %cl    /* is it the source indicator */
246         jz      0b           /* Ignore it otherwise */
247         movl    %ecx,   %esi /* For every source page do a copy */
248         andl    $0xfffff000, %esi
249 
250         movl    %edi, %eax
251         movl    %esi, %ebp
252 
253         movl    %edx, %edi
254         movl    $1024, %ecx
255         rep ; movsl
256 
257         movl    %ebp, %edi
258         movl    %eax, %esi
259         movl    $1024, %ecx
260         rep ; movsl
261 
262         movl    %eax, %edi
263         movl    %edx, %esi
264         movl    $1024, %ecx
265         rep ; movsl
266 
267         lea     PAGE_SIZE(%ebp), %esi
268         jmp     0b
269 3:
270         popl    %esi
271         popl    %edi
272         popl    %ebx
273         popl    %ebp
274         ret
275 
276         .globl kexec_control_code_size
277 .set kexec_control_code_size, . - relocate_kernel

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