| blob | 8a154b940feff8880904440cc2975c1851784879 |
1 /*
2 * linux/arch/arm/kernel/head.S
3 *
4 * Copyright (C) 1994-2002 Russell King
5 * Copyright (c) 2003 ARM Limited
6 * All Rights Reserved
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/linkage.h>
15 #include <linux/init.h>
17 #include <asm/assembler.h>
18 #include <asm/domain.h>
19 #include <asm/ptrace.h>
20 #include <asm/asm-offsets.h>
21 #include <asm/memory.h>
22 #include <asm/thread_info.h>
23 #include <asm/system.h>
25 #ifdef CONFIG_DEBUG_LL
26 #include <mach/debug-macro.S>
27 #endif
29 #if (PHYS_OFFSET & 0x001fffff)
30 #error "PHYS_OFFSET must be at an even 2MiB boundary!"
31 #endif
33 #define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
34 #define KERNEL_RAM_PADDR (PHYS_OFFSET + TEXT_OFFSET)
37 /*
38 * swapper_pg_dir is the virtual address of the initial page table.
39 * We place the page tables 16K below KERNEL_RAM_VADDR. Therefore, we must
40 * make sure that KERNEL_RAM_VADDR 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_VADDR >= PAGE_OFFSET + 0x4000.
43 */
44 #if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
45 #error KERNEL_RAM_VADDR must start at 0xXXXX8000
46 #endif
48 .globl swapper_pg_dir
49 .equ swapper_pg_dir, KERNEL_RAM_VADDR - 0x4000
51 .macro pgtbl, rd
52 ldr \rd, =(KERNEL_RAM_PADDR - 0x4000)
53 .endm
55 #ifdef CONFIG_XIP_KERNEL
56 #define KERNEL_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
57 #define KERNEL_END _edata_loc
58 #else
59 #define KERNEL_START KERNEL_RAM_VADDR
60 #define KERNEL_END _end
61 #endif
63 /*
64 * Kernel startup entry point.
65 * ---------------------------
66 *
67 * This is normally called from the decompressor code. The requirements
68 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
69 * r1 = machine nr, r2 = atags pointer.
70 *
71 * This code is mostly position independent, so if you link the kernel at
72 * 0xc0008000, you call this at __pa(0xc0008000).
73 *
74 * See linux/arch/arm/tools/mach-types for the complete list of machine
75 * numbers for r1.
76 *
77 * We're trying to keep crap to a minimum; DO NOT add any machine specific
78 * crap here - that's what the boot loader (or in extreme, well justified
79 * circumstances, zImage) is for.
80 */
81 __HEAD
82 ENTRY(stext)
83 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
84 @ and irqs disabled
85 mrc p15, 0, r9, c0, c0 @ get processor id
86 bl __lookup_processor_type @ r5=procinfo r9=cpuid
87 movs r10, r5 @ invalid processor (r5=0)?
88 THUMB( it eq ) @ force fixup-able long branch encoding
89 beq __error_p @ yes, error 'p'
91 /*
92 * r1 = machine no, r2 = atags,
93 * r9 = cpuid, r10 = procinfo
94 */
95 bl __vet_atags
96 #ifdef CONFIG_SMP_ON_UP
97 bl __fixup_smp
98 #endif
99 bl __create_page_tables
101 /*
102 * The following calls CPU specific code in a position independent
103 * manner. See arch/arm/mm/proc-*.S for details. r10 = base of
104 * xxx_proc_info structure selected by __lookup_processor_type
105 * above. On return, the CPU will be ready for the MMU to be
106 * turned on, and r0 will hold the CPU control register value.
107 */
108 ldr r13, =__mmap_switched @ address to jump to after
109 @ mmu has been enabled
110 adr lr, BSYM(1f) @ return (PIC) address
111 ARM( add pc, r10, #PROCINFO_INITFUNC )
112 THUMB( add r12, r10, #PROCINFO_INITFUNC )
113 THUMB( mov pc, r12 )
114 1: b __enable_mmu
115 ENDPROC(stext)
116 .ltorg
118 /*
119 * Setup the initial page tables. We only setup the barest
120 * amount which are required to get the kernel running, which
121 * generally means mapping in the kernel code.
122 *
123 * r9 = cpuid
124 * r10 = procinfo
125 *
126 * Returns:
127 * r0, r3, r5-r7 corrupted
128 * r4 = physical page table address
129 */
130 __create_page_tables:
131 pgtbl r4 @ page table address
133 /*
134 * Clear the 16K level 1 swapper page table
135 */
136 mov r0, r4
137 mov r3, #0
138 add r6, r0, #0x4000
139 1: str r3, [r0], #4
140 str r3, [r0], #4
141 str r3, [r0], #4
142 str r3, [r0], #4
143 teq r0, r6
144 bne 1b
146 ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags
148 /*
149 * Create identity mapping to cater for __enable_mmu.
150 * This identity mapping will be removed by paging_init().
151 */
152 adr r0, __enable_mmu_loc
153 ldmia r0, {r3, r5, r6}
154 sub r0, r0, r3 @ virt->phys offset
155 add r5, r5, r0 @ phys __enable_mmu
156 add r6, r6, r0 @ phys __enable_mmu_end
157 mov r5, r5, lsr #20
158 mov r6, r6, lsr #20
160 1: orr r3, r7, r5, lsl #20 @ flags + kernel base
161 str r3, [r4, r5, lsl #2] @ identity mapping
162 teq r5, r6
163 addne r5, r5, #1 @ next section
164 bne 1b
166 /*
167 * Now setup the pagetables for our kernel direct
168 * mapped region.
169 */
170 mov r3, pc
171 mov r3, r3, lsr #20
172 orr r3, r7, r3, lsl #20
173 add r0, r4, #(KERNEL_START & 0xff000000) >> 18
174 str r3, [r0, #(KERNEL_START & 0x00f00000) >> 18]!
175 ldr r6, =(KERNEL_END - 1)
176 add r0, r0, #4
177 add r6, r4, r6, lsr #18
178 1: cmp r0, r6
179 add r3, r3, #1 << 20
180 strls r3, [r0], #4
181 bls 1b
183 #ifdef CONFIG_XIP_KERNEL
184 /*
185 * Map some ram to cover our .data and .bss areas.
186 */
187 orr r3, r7, #(KERNEL_RAM_PADDR & 0xff000000)
188 .if (KERNEL_RAM_PADDR & 0x00f00000)
189 orr r3, r3, #(KERNEL_RAM_PADDR & 0x00f00000)
190 .endif
191 add r0, r4, #(KERNEL_RAM_VADDR & 0xff000000) >> 18
192 str r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> 18]!
193 ldr r6, =(_end - 1)
194 add r0, r0, #4
195 add r6, r4, r6, lsr #18
196 1: cmp r0, r6
197 add r3, r3, #1 << 20
198 strls r3, [r0], #4
199 bls 1b
200 #endif
202 /*
203 * Then map first 1MB of ram in case it contains our boot params.
204 */
205 add r0, r4, #PAGE_OFFSET >> 18
206 orr r6, r7, #(PHYS_OFFSET & 0xff000000)
207 .if (PHYS_OFFSET & 0x00f00000)
208 orr r6, r6, #(PHYS_OFFSET & 0x00f00000)
209 .endif
210 str r6, [r0]
212 #ifdef CONFIG_DEBUG_LL
213 #ifndef CONFIG_DEBUG_ICEDCC
214 /*
215 * Map in IO space for serial debugging.
216 * This allows debug messages to be output
217 * via a serial console before paging_init.
218 */
219 addruart r7, r3
221 mov r3, r3, lsr #20
222 mov r3, r3, lsl #2
224 add r0, r4, r3
225 rsb r3, r3, #0x4000 @ PTRS_PER_PGD*sizeof(long)
226 cmp r3, #0x0800 @ limit to 512MB
227 movhi r3, #0x0800
228 add r6, r0, r3
229 mov r3, r7, lsr #20
230 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
231 orr r3, r7, r3, lsl #20
232 1: str r3, [r0], #4
233 add r3, r3, #1 << 20
234 teq r0, r6
235 bne 1b
237 #else /* CONFIG_DEBUG_ICEDCC */
238 /* we don't need any serial debugging mappings for ICEDCC */
239 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
240 #endif /* !CONFIG_DEBUG_ICEDCC */
242 #if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
243 /*
244 * If we're using the NetWinder or CATS, we also need to map
245 * in the 16550-type serial port for the debug messages
246 */
247 add r0, r4, #0xff000000 >> 18
248 orr r3, r7, #0x7c000000
249 str r3, [r0]
250 #endif
251 #ifdef CONFIG_ARCH_RPC
252 /*
253 * Map in screen at 0x02000000 & SCREEN2_BASE
254 * Similar reasons here - for debug. This is
255 * only for Acorn RiscPC architectures.
256 */
257 add r0, r4, #0x02000000 >> 18
258 orr r3, r7, #0x02000000
259 str r3, [r0]
260 add r0, r4, #0xd8000000 >> 18
261 str r3, [r0]
262 #endif
263 #endif
264 mov pc, lr
265 ENDPROC(__create_page_tables)
266 .ltorg
267 .align
268 __enable_mmu_loc:
269 .long .
270 .long __enable_mmu
271 .long __enable_mmu_end
273 #if defined(CONFIG_SMP)
274 __CPUINIT
275 ENTRY(secondary_startup)
276 /*
277 * Common entry point for secondary CPUs.
278 *
279 * Ensure that we're in SVC mode, and IRQs are disabled. Lookup
280 * the processor type - there is no need to check the machine type
281 * as it has already been validated by the primary processor.
282 */
283 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9
284 mrc p15, 0, r9, c0, c0 @ get processor id
285 bl __lookup_processor_type
286 movs r10, r5 @ invalid processor?
287 moveq r0, #'p' @ yes, error 'p'
288 THUMB( it eq ) @ force fixup-able long branch encoding
289 beq __error_p
291 /*
292 * Use the page tables supplied from __cpu_up.
293 */
294 adr r4, __secondary_data
295 ldmia r4, {r5, r7, r12} @ address to jump to after
296 sub r4, r4, r5 @ mmu has been enabled
297 ldr r4, [r7, r4] @ get secondary_data.pgdir
298 adr lr, BSYM(__enable_mmu) @ return address
299 mov r13, r12 @ __secondary_switched address
300 ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor
301 @ (return control reg)
302 THUMB( add r12, r10, #PROCINFO_INITFUNC )
303 THUMB( mov pc, r12 )
304 ENDPROC(secondary_startup)
306 /*
307 * r6 = &secondary_data
308 */
309 ENTRY(__secondary_switched)
310 ldr sp, [r7, #4] @ get secondary_data.stack
311 mov fp, #0
312 b secondary_start_kernel
313 ENDPROC(__secondary_switched)
315 .align
317 .type __secondary_data, %object
318 __secondary_data:
319 .long .
320 .long secondary_data
321 .long __secondary_switched
322 #endif /* defined(CONFIG_SMP) */
326 /*
327 * Setup common bits before finally enabling the MMU. Essentially
328 * this is just loading the page table pointer and domain access
329 * registers.
330 *
331 * r0 = cp#15 control register
332 * r1 = machine ID
333 * r2 = atags pointer
334 * r4 = page table pointer
335 * r9 = processor ID
336 * r13 = *virtual* address to jump to upon completion
337 */
338 __enable_mmu:
339 #ifdef CONFIG_ALIGNMENT_TRAP
340 orr r0, r0, #CR_A
341 #else
342 bic r0, r0, #CR_A
343 #endif
344 #ifdef CONFIG_CPU_DCACHE_DISABLE
345 bic r0, r0, #CR_C
346 #endif
347 #ifdef CONFIG_CPU_BPREDICT_DISABLE
348 bic r0, r0, #CR_Z
349 #endif
350 #ifdef CONFIG_CPU_ICACHE_DISABLE
351 bic r0, r0, #CR_I
352 #endif
353 mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
354 domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
355 domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \
356 domain_val(DOMAIN_IO, DOMAIN_CLIENT))
357 mcr p15, 0, r5, c3, c0, 0 @ load domain access register
358 mcr p15, 0, r4, c2, c0, 0 @ load page table pointer
359 b __turn_mmu_on
360 ENDPROC(__enable_mmu)
362 /*
363 * Enable the MMU. This completely changes the structure of the visible
364 * memory space. You will not be able to trace execution through this.
365 * If you have an enquiry about this, *please* check the linux-arm-kernel
366 * mailing list archives BEFORE sending another post to the list.
367 *
368 * r0 = cp#15 control register
369 * r1 = machine ID
370 * r2 = atags pointer
371 * r9 = processor ID
372 * r13 = *virtual* address to jump to upon completion
373 *
374 * other registers depend on the function called upon completion
375 */
376 .align 5
377 __turn_mmu_on:
378 mov r0, r0
379 mcr p15, 0, r0, c1, c0, 0 @ write control reg
380 mrc p15, 0, r3, c0, c0, 0 @ read id reg
381 mov r3, r3
382 mov r3, r13
383 mov pc, r3
384 __enable_mmu_end:
385 ENDPROC(__turn_mmu_on)
388 #ifdef CONFIG_SMP_ON_UP
389 __fixup_smp:
390 and r3, r9, #0x000f0000 @ architecture version
391 teq r3, #0x000f0000 @ CPU ID supported?
392 bne __fixup_smp_on_up @ no, assume UP
394 bic r3, r9, #0x00ff0000
395 bic r3, r3, #0x0000000f @ mask 0xff00fff0
396 mov r4, #0x41000000
397 orr r4, r4, #0x0000b000
398 orr r4, r4, #0x00000020 @ val 0x4100b020
399 teq r3, r4 @ ARM 11MPCore?
400 moveq pc, lr @ yes, assume SMP
402 mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
403 and r0, r0, #0xc0000000 @ multiprocessing extensions and
404 teq r0, #0x80000000 @ not part of a uniprocessor system?
405 moveq pc, lr @ yes, assume SMP
407 __fixup_smp_on_up:
408 adr r0, 1f
409 ldmia r0, {r3 - r5}
410 sub r3, r0, r3
411 add r4, r4, r3
412 add r5, r5, r3
413 2: cmp r4, r5
414 movhs pc, lr
415 ldmia r4!, {r0, r6}
416 ARM( str r6, [r0, r3] )
417 THUMB( add r0, r0, r3 )
418 #ifdef __ARMEB__
419 THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian.
420 #endif
421 THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords
422 THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3.
423 THUMB( strh r6, [r0] )
424 b 2b
425 ENDPROC(__fixup_smp)
427 .align
428 1: .word .
429 .word __smpalt_begin
430 .word __smpalt_end
432 .pushsection .data
433 .globl smp_on_up
434 smp_on_up:
435 ALT_SMP(.long 1)
436 ALT_UP(.long 0)
437 .popsection
439 #endif
441 #include "head-common.S"