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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm/kernel/head.S | |
3 | * | |
4 | * Copyright (C) 1994-2002 Russell King | |
e65f38ed RK |
5 | * Copyright (c) 2003 ARM Limited |
6 | * All Rights Reserved | |
1da177e4 LT |
7 | * |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | * Kernel startup code for all 32-bit CPUs | |
13 | */ | |
14 | #include <linux/config.h> | |
15 | #include <linux/linkage.h> | |
16 | #include <linux/init.h> | |
17 | ||
18 | #include <asm/assembler.h> | |
19 | #include <asm/domain.h> | |
20 | #include <asm/mach-types.h> | |
21 | #include <asm/procinfo.h> | |
22 | #include <asm/ptrace.h> | |
e6ae744d | 23 | #include <asm/asm-offsets.h> |
f09b9979 | 24 | #include <asm/memory.h> |
4f7a1812 | 25 | #include <asm/thread_info.h> |
1da177e4 LT |
26 | #include <asm/system.h> |
27 | ||
28 | #define PROCINFO_MMUFLAGS 8 | |
29 | #define PROCINFO_INITFUNC 12 | |
30 | ||
31 | #define MACHINFO_TYPE 0 | |
32 | #define MACHINFO_PHYSRAM 4 | |
33 | #define MACHINFO_PHYSIO 8 | |
34 | #define MACHINFO_PGOFFIO 12 | |
35 | #define MACHINFO_NAME 16 | |
36 | ||
1da177e4 | 37 | /* |
37d07b72 NP |
38 | * swapper_pg_dir is the virtual address of the initial page table. |
39 | * We place the page tables 16K below KERNEL_RAM_ADDR. Therefore, we must | |
40 | * make sure that KERNEL_RAM_ADDR is correctly set. Currently, we expect | |
41 | * the least significant 16 bits to be 0x8000, but we could probably | |
42 | * relax this restriction to KERNEL_RAM_ADDR >= PAGE_OFFSET + 0x4000. | |
1da177e4 | 43 | */ |
37d07b72 NP |
44 | #if (KERNEL_RAM_ADDR & 0xffff) != 0x8000 |
45 | #error KERNEL_RAM_ADDR must start at 0xXXXX8000 | |
1da177e4 LT |
46 | #endif |
47 | ||
48 | .globl swapper_pg_dir | |
37d07b72 | 49 | .equ swapper_pg_dir, KERNEL_RAM_ADDR - 0x4000 |
1da177e4 | 50 | |
37d07b72 NP |
51 | .macro pgtbl, rd |
52 | ldr \rd, =(__virt_to_phys(KERNEL_RAM_ADDR - 0x4000)) | |
1da177e4 | 53 | .endm |
1da177e4 | 54 | |
37d07b72 NP |
55 | #ifdef CONFIG_XIP_KERNEL |
56 | #define TEXTADDR XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) | |
57 | #else | |
58 | #define TEXTADDR KERNEL_RAM_ADDR | |
1da177e4 LT |
59 | #endif |
60 | ||
61 | /* | |
62 | * Kernel startup entry point. | |
63 | * --------------------------- | |
64 | * | |
65 | * This is normally called from the decompressor code. The requirements | |
66 | * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0, | |
67 | * r1 = machine nr. | |
68 | * | |
69 | * This code is mostly position independent, so if you link the kernel at | |
70 | * 0xc0008000, you call this at __pa(0xc0008000). | |
71 | * | |
72 | * See linux/arch/arm/tools/mach-types for the complete list of machine | |
73 | * numbers for r1. | |
74 | * | |
75 | * We're trying to keep crap to a minimum; DO NOT add any machine specific | |
76 | * crap here - that's what the boot loader (or in extreme, well justified | |
77 | * circumstances, zImage) is for. | |
78 | */ | |
79 | __INIT | |
80 | .type stext, %function | |
81 | ENTRY(stext) | |
82 | msr cpsr_c, #PSR_F_BIT | PSR_I_BIT | MODE_SVC @ ensure svc mode | |
83 | @ and irqs disabled | |
84 | bl __lookup_processor_type @ r5=procinfo r9=cpuid | |
85 | movs r10, r5 @ invalid processor (r5=0)? | |
86 | beq __error_p @ yes, error 'p' | |
87 | bl __lookup_machine_type @ r5=machinfo | |
88 | movs r8, r5 @ invalid machine (r5=0)? | |
89 | beq __error_a @ yes, error 'a' | |
90 | bl __create_page_tables | |
91 | ||
92 | /* | |
93 | * The following calls CPU specific code in a position independent | |
94 | * manner. See arch/arm/mm/proc-*.S for details. r10 = base of | |
95 | * xxx_proc_info structure selected by __lookup_machine_type | |
96 | * above. On return, the CPU will be ready for the MMU to be | |
97 | * turned on, and r0 will hold the CPU control register value. | |
98 | */ | |
99 | ldr r13, __switch_data @ address to jump to after | |
100 | @ mmu has been enabled | |
101 | adr lr, __enable_mmu @ return (PIC) address | |
102 | add pc, r10, #PROCINFO_INITFUNC | |
103 | ||
104 | .type __switch_data, %object | |
105 | __switch_data: | |
106 | .long __mmap_switched | |
107 | .long __data_loc @ r4 | |
108 | .long __data_start @ r5 | |
109 | .long __bss_start @ r6 | |
110 | .long _end @ r7 | |
111 | .long processor_id @ r4 | |
112 | .long __machine_arch_type @ r5 | |
113 | .long cr_alignment @ r6 | |
4f7a1812 | 114 | .long init_thread_union + THREAD_START_SP @ sp |
1da177e4 LT |
115 | |
116 | /* | |
117 | * The following fragment of code is executed with the MMU on, and uses | |
118 | * absolute addresses; this is not position independent. | |
119 | * | |
120 | * r0 = cp#15 control register | |
121 | * r1 = machine ID | |
122 | * r9 = processor ID | |
123 | */ | |
124 | .type __mmap_switched, %function | |
125 | __mmap_switched: | |
126 | adr r3, __switch_data + 4 | |
127 | ||
128 | ldmia r3!, {r4, r5, r6, r7} | |
129 | cmp r4, r5 @ Copy data segment if needed | |
130 | 1: cmpne r5, r6 | |
131 | ldrne fp, [r4], #4 | |
132 | strne fp, [r5], #4 | |
133 | bne 1b | |
134 | ||
135 | mov fp, #0 @ Clear BSS (and zero fp) | |
136 | 1: cmp r6, r7 | |
137 | strcc fp, [r6],#4 | |
138 | bcc 1b | |
139 | ||
140 | ldmia r3, {r4, r5, r6, sp} | |
141 | str r9, [r4] @ Save processor ID | |
142 | str r1, [r5] @ Save machine type | |
143 | bic r4, r0, #CR_A @ Clear 'A' bit | |
144 | stmia r6, {r0, r4} @ Save control register values | |
145 | b start_kernel | |
146 | ||
e65f38ed RK |
147 | #if defined(CONFIG_SMP) |
148 | .type secondary_startup, #function | |
149 | ENTRY(secondary_startup) | |
150 | /* | |
151 | * Common entry point for secondary CPUs. | |
152 | * | |
153 | * Ensure that we're in SVC mode, and IRQs are disabled. Lookup | |
154 | * the processor type - there is no need to check the machine type | |
155 | * as it has already been validated by the primary processor. | |
156 | */ | |
157 | msr cpsr_c, #PSR_F_BIT | PSR_I_BIT | MODE_SVC | |
158 | bl __lookup_processor_type | |
159 | movs r10, r5 @ invalid processor? | |
160 | moveq r0, #'p' @ yes, error 'p' | |
161 | beq __error | |
162 | ||
163 | /* | |
164 | * Use the page tables supplied from __cpu_up. | |
165 | */ | |
166 | adr r4, __secondary_data | |
167 | ldmia r4, {r5, r6, r13} @ address to jump to after | |
168 | sub r4, r4, r5 @ mmu has been enabled | |
169 | ldr r4, [r6, r4] @ get secondary_data.pgdir | |
170 | adr lr, __enable_mmu @ return address | |
171 | add pc, r10, #12 @ initialise processor | |
172 | @ (return control reg) | |
173 | ||
174 | /* | |
175 | * r6 = &secondary_data | |
176 | */ | |
177 | ENTRY(__secondary_switched) | |
178 | ldr sp, [r6, #4] @ get secondary_data.stack | |
179 | mov fp, #0 | |
180 | b secondary_start_kernel | |
181 | ||
182 | .type __secondary_data, %object | |
183 | __secondary_data: | |
184 | .long . | |
185 | .long secondary_data | |
186 | .long __secondary_switched | |
187 | #endif /* defined(CONFIG_SMP) */ | |
188 | ||
1da177e4 LT |
189 | |
190 | ||
191 | /* | |
192 | * Setup common bits before finally enabling the MMU. Essentially | |
193 | * this is just loading the page table pointer and domain access | |
194 | * registers. | |
195 | */ | |
196 | .type __enable_mmu, %function | |
197 | __enable_mmu: | |
198 | #ifdef CONFIG_ALIGNMENT_TRAP | |
199 | orr r0, r0, #CR_A | |
200 | #else | |
201 | bic r0, r0, #CR_A | |
202 | #endif | |
203 | #ifdef CONFIG_CPU_DCACHE_DISABLE | |
204 | bic r0, r0, #CR_C | |
205 | #endif | |
206 | #ifdef CONFIG_CPU_BPREDICT_DISABLE | |
207 | bic r0, r0, #CR_Z | |
208 | #endif | |
209 | #ifdef CONFIG_CPU_ICACHE_DISABLE | |
210 | bic r0, r0, #CR_I | |
211 | #endif | |
212 | mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \ | |
213 | domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \ | |
214 | domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \ | |
215 | domain_val(DOMAIN_IO, DOMAIN_CLIENT)) | |
216 | mcr p15, 0, r5, c3, c0, 0 @ load domain access register | |
217 | mcr p15, 0, r4, c2, c0, 0 @ load page table pointer | |
218 | b __turn_mmu_on | |
219 | ||
220 | /* | |
221 | * Enable the MMU. This completely changes the structure of the visible | |
222 | * memory space. You will not be able to trace execution through this. | |
223 | * If you have an enquiry about this, *please* check the linux-arm-kernel | |
224 | * mailing list archives BEFORE sending another post to the list. | |
225 | * | |
226 | * r0 = cp#15 control register | |
227 | * r13 = *virtual* address to jump to upon completion | |
228 | * | |
229 | * other registers depend on the function called upon completion | |
230 | */ | |
231 | .align 5 | |
232 | .type __turn_mmu_on, %function | |
233 | __turn_mmu_on: | |
234 | mov r0, r0 | |
235 | mcr p15, 0, r0, c1, c0, 0 @ write control reg | |
236 | mrc p15, 0, r3, c0, c0, 0 @ read id reg | |
237 | mov r3, r3 | |
238 | mov r3, r3 | |
239 | mov pc, r13 | |
240 | ||
241 | ||
242 | ||
243 | /* | |
244 | * Setup the initial page tables. We only setup the barest | |
245 | * amount which are required to get the kernel running, which | |
246 | * generally means mapping in the kernel code. | |
247 | * | |
248 | * r8 = machinfo | |
249 | * r9 = cpuid | |
250 | * r10 = procinfo | |
251 | * | |
252 | * Returns: | |
253 | * r0, r3, r5, r6, r7 corrupted | |
254 | * r4 = physical page table address | |
255 | */ | |
256 | .type __create_page_tables, %function | |
257 | __create_page_tables: | |
258 | ldr r5, [r8, #MACHINFO_PHYSRAM] @ physram | |
37d07b72 | 259 | pgtbl r4 @ page table address |
1da177e4 LT |
260 | |
261 | /* | |
262 | * Clear the 16K level 1 swapper page table | |
263 | */ | |
264 | mov r0, r4 | |
265 | mov r3, #0 | |
266 | add r6, r0, #0x4000 | |
267 | 1: str r3, [r0], #4 | |
268 | str r3, [r0], #4 | |
269 | str r3, [r0], #4 | |
270 | str r3, [r0], #4 | |
271 | teq r0, r6 | |
272 | bne 1b | |
273 | ||
274 | ldr r7, [r10, #PROCINFO_MMUFLAGS] @ mmuflags | |
275 | ||
276 | /* | |
277 | * Create identity mapping for first MB of kernel to | |
278 | * cater for the MMU enable. This identity mapping | |
279 | * will be removed by paging_init(). We use our current program | |
280 | * counter to determine corresponding section base address. | |
281 | */ | |
282 | mov r6, pc, lsr #20 @ start of kernel section | |
283 | orr r3, r7, r6, lsl #20 @ flags + kernel base | |
284 | str r3, [r4, r6, lsl #2] @ identity mapping | |
285 | ||
286 | /* | |
287 | * Now setup the pagetables for our kernel direct | |
288 | * mapped region. We round TEXTADDR down to the | |
289 | * nearest megabyte boundary. It is assumed that | |
290 | * the kernel fits within 4 contigous 1MB sections. | |
291 | */ | |
292 | add r0, r4, #(TEXTADDR & 0xff000000) >> 18 @ start of kernel | |
293 | str r3, [r0, #(TEXTADDR & 0x00f00000) >> 18]! | |
294 | add r3, r3, #1 << 20 | |
295 | str r3, [r0, #4]! @ KERNEL + 1MB | |
296 | add r3, r3, #1 << 20 | |
297 | str r3, [r0, #4]! @ KERNEL + 2MB | |
298 | add r3, r3, #1 << 20 | |
299 | str r3, [r0, #4] @ KERNEL + 3MB | |
300 | ||
301 | /* | |
302 | * Then map first 1MB of ram in case it contains our boot params. | |
303 | */ | |
f09b9979 | 304 | add r0, r4, #PAGE_OFFSET >> 18 |
1da177e4 LT |
305 | orr r6, r5, r7 |
306 | str r6, [r0] | |
307 | ||
308 | #ifdef CONFIG_XIP_KERNEL | |
309 | /* | |
310 | * Map some ram to cover our .data and .bss areas. | |
311 | * Mapping 3MB should be plenty. | |
312 | */ | |
313 | sub r3, r4, r5 | |
314 | mov r3, r3, lsr #20 | |
315 | add r0, r0, r3, lsl #2 | |
316 | add r6, r6, r3, lsl #20 | |
317 | str r6, [r0], #4 | |
318 | add r6, r6, #(1 << 20) | |
319 | str r6, [r0], #4 | |
320 | add r6, r6, #(1 << 20) | |
321 | str r6, [r0] | |
322 | #endif | |
323 | ||
c77b0427 | 324 | #ifdef CONFIG_DEBUG_LL |
1da177e4 LT |
325 | bic r7, r7, #0x0c @ turn off cacheable |
326 | @ and bufferable bits | |
1da177e4 LT |
327 | /* |
328 | * Map in IO space for serial debugging. | |
329 | * This allows debug messages to be output | |
330 | * via a serial console before paging_init. | |
331 | */ | |
332 | ldr r3, [r8, #MACHINFO_PGOFFIO] | |
333 | add r0, r4, r3 | |
334 | rsb r3, r3, #0x4000 @ PTRS_PER_PGD*sizeof(long) | |
335 | cmp r3, #0x0800 @ limit to 512MB | |
336 | movhi r3, #0x0800 | |
337 | add r6, r0, r3 | |
338 | ldr r3, [r8, #MACHINFO_PHYSIO] | |
339 | orr r3, r3, r7 | |
340 | 1: str r3, [r0], #4 | |
341 | add r3, r3, #1 << 20 | |
342 | teq r0, r6 | |
343 | bne 1b | |
344 | #if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS) | |
345 | /* | |
346 | * If we're using the NetWinder, we need to map in | |
347 | * the 16550-type serial port for the debug messages | |
348 | */ | |
349 | teq r1, #MACH_TYPE_NETWINDER | |
350 | teqne r1, #MACH_TYPE_CATS | |
351 | bne 1f | |
c77b0427 RK |
352 | add r0, r4, #0xff000000 >> 18 |
353 | orr r3, r7, #0x7c000000 | |
354 | str r3, [r0] | |
1da177e4 LT |
355 | 1: |
356 | #endif | |
1da177e4 LT |
357 | #ifdef CONFIG_ARCH_RPC |
358 | /* | |
359 | * Map in screen at 0x02000000 & SCREEN2_BASE | |
360 | * Similar reasons here - for debug. This is | |
361 | * only for Acorn RiscPC architectures. | |
362 | */ | |
c77b0427 RK |
363 | add r0, r4, #0x02000000 >> 18 |
364 | orr r3, r7, #0x02000000 | |
1da177e4 | 365 | str r3, [r0] |
c77b0427 | 366 | add r0, r4, #0xd8000000 >> 18 |
1da177e4 | 367 | str r3, [r0] |
c77b0427 | 368 | #endif |
1da177e4 LT |
369 | #endif |
370 | mov pc, lr | |
371 | .ltorg | |
372 | ||
373 | ||
374 | ||
375 | /* | |
376 | * Exception handling. Something went wrong and we can't proceed. We | |
377 | * ought to tell the user, but since we don't have any guarantee that | |
378 | * we're even running on the right architecture, we do virtually nothing. | |
379 | * | |
380 | * If CONFIG_DEBUG_LL is set we try to print out something about the error | |
381 | * and hope for the best (useful if bootloader fails to pass a proper | |
382 | * machine ID for example). | |
383 | */ | |
384 | ||
385 | .type __error_p, %function | |
386 | __error_p: | |
387 | #ifdef CONFIG_DEBUG_LL | |
388 | adr r0, str_p1 | |
389 | bl printascii | |
390 | b __error | |
391 | str_p1: .asciz "\nError: unrecognized/unsupported processor variant.\n" | |
392 | .align | |
393 | #endif | |
394 | ||
395 | .type __error_a, %function | |
396 | __error_a: | |
397 | #ifdef CONFIG_DEBUG_LL | |
398 | mov r4, r1 @ preserve machine ID | |
399 | adr r0, str_a1 | |
400 | bl printascii | |
401 | mov r0, r4 | |
402 | bl printhex8 | |
403 | adr r0, str_a2 | |
404 | bl printascii | |
405 | adr r3, 3f | |
406 | ldmia r3, {r4, r5, r6} @ get machine desc list | |
407 | sub r4, r3, r4 @ get offset between virt&phys | |
408 | add r5, r5, r4 @ convert virt addresses to | |
409 | add r6, r6, r4 @ physical address space | |
410 | 1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type | |
411 | bl printhex8 | |
412 | mov r0, #'\t' | |
413 | bl printch | |
414 | ldr r0, [r5, #MACHINFO_NAME] @ get machine name | |
415 | add r0, r0, r4 | |
416 | bl printascii | |
417 | mov r0, #'\n' | |
418 | bl printch | |
419 | add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc | |
420 | cmp r5, r6 | |
421 | blo 1b | |
422 | adr r0, str_a3 | |
423 | bl printascii | |
424 | b __error | |
425 | str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x" | |
426 | str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n" | |
427 | str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n" | |
428 | .align | |
429 | #endif | |
430 | ||
431 | .type __error, %function | |
432 | __error: | |
433 | #ifdef CONFIG_ARCH_RPC | |
434 | /* | |
435 | * Turn the screen red on a error - RiscPC only. | |
436 | */ | |
437 | mov r0, #0x02000000 | |
438 | mov r3, #0x11 | |
439 | orr r3, r3, r3, lsl #8 | |
440 | orr r3, r3, r3, lsl #16 | |
441 | str r3, [r0], #4 | |
442 | str r3, [r0], #4 | |
443 | str r3, [r0], #4 | |
444 | str r3, [r0], #4 | |
445 | #endif | |
446 | 1: mov r0, r0 | |
447 | b 1b | |
448 | ||
449 | ||
450 | /* | |
451 | * Read processor ID register (CP#15, CR0), and look up in the linker-built | |
452 | * supported processor list. Note that we can't use the absolute addresses | |
453 | * for the __proc_info lists since we aren't running with the MMU on | |
454 | * (and therefore, we are not in the correct address space). We have to | |
455 | * calculate the offset. | |
456 | * | |
457 | * Returns: | |
458 | * r3, r4, r6 corrupted | |
459 | * r5 = proc_info pointer in physical address space | |
460 | * r9 = cpuid | |
461 | */ | |
462 | .type __lookup_processor_type, %function | |
463 | __lookup_processor_type: | |
464 | adr r3, 3f | |
465 | ldmda r3, {r5, r6, r9} | |
466 | sub r3, r3, r9 @ get offset between virt&phys | |
467 | add r5, r5, r3 @ convert virt addresses to | |
468 | add r6, r6, r3 @ physical address space | |
469 | mrc p15, 0, r9, c0, c0 @ get processor id | |
470 | 1: ldmia r5, {r3, r4} @ value, mask | |
471 | and r4, r4, r9 @ mask wanted bits | |
472 | teq r3, r4 | |
473 | beq 2f | |
474 | add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list) | |
475 | cmp r5, r6 | |
476 | blo 1b | |
477 | mov r5, #0 @ unknown processor | |
478 | 2: mov pc, lr | |
479 | ||
480 | /* | |
481 | * This provides a C-API version of the above function. | |
482 | */ | |
483 | ENTRY(lookup_processor_type) | |
484 | stmfd sp!, {r4 - r6, r9, lr} | |
485 | bl __lookup_processor_type | |
486 | mov r0, r5 | |
487 | ldmfd sp!, {r4 - r6, r9, pc} | |
488 | ||
489 | /* | |
490 | * Look in include/asm-arm/procinfo.h and arch/arm/kernel/arch.[ch] for | |
491 | * more information about the __proc_info and __arch_info structures. | |
492 | */ | |
493 | .long __proc_info_begin | |
494 | .long __proc_info_end | |
495 | 3: .long . | |
496 | .long __arch_info_begin | |
497 | .long __arch_info_end | |
498 | ||
499 | /* | |
500 | * Lookup machine architecture in the linker-build list of architectures. | |
501 | * Note that we can't use the absolute addresses for the __arch_info | |
502 | * lists since we aren't running with the MMU on (and therefore, we are | |
503 | * not in the correct address space). We have to calculate the offset. | |
504 | * | |
505 | * r1 = machine architecture number | |
506 | * Returns: | |
507 | * r3, r4, r6 corrupted | |
508 | * r5 = mach_info pointer in physical address space | |
509 | */ | |
510 | .type __lookup_machine_type, %function | |
511 | __lookup_machine_type: | |
512 | adr r3, 3b | |
513 | ldmia r3, {r4, r5, r6} | |
514 | sub r3, r3, r4 @ get offset between virt&phys | |
515 | add r5, r5, r3 @ convert virt addresses to | |
516 | add r6, r6, r3 @ physical address space | |
517 | 1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type | |
518 | teq r3, r1 @ matches loader number? | |
519 | beq 2f @ found | |
520 | add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc | |
521 | cmp r5, r6 | |
522 | blo 1b | |
523 | mov r5, #0 @ unknown machine | |
524 | 2: mov pc, lr | |
525 | ||
526 | /* | |
527 | * This provides a C-API version of the above function. | |
528 | */ | |
529 | ENTRY(lookup_machine_type) | |
530 | stmfd sp!, {r4 - r6, lr} | |
531 | mov r1, r0 | |
532 | bl __lookup_machine_type | |
533 | mov r0, r5 | |
534 | ldmfd sp!, {r4 - r6, pc} |