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1/*
2 * linux/arch/arm/kernel/head-common.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 */
13
14#define ATAG_CORE 0x54410001
15#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
16#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
17
18#ifdef CONFIG_CPU_BIG_ENDIAN
19#define OF_DT_MAGIC 0xd00dfeed
20#else
21#define OF_DT_MAGIC 0xedfe0dd0 /* 0xd00dfeed in big-endian */
22#endif
23
24/*
25 * Exception handling. Something went wrong and we can't proceed. We
26 * ought to tell the user, but since we don't have any guarantee that
27 * we're even running on the right architecture, we do virtually nothing.
28 *
29 * If CONFIG_DEBUG_LL is set we try to print out something about the error
30 * and hope for the best (useful if bootloader fails to pass a proper
31 * machine ID for example).
32 */
33 __HEAD
34
35/* Determine validity of the r2 atags pointer. The heuristic requires
36 * that the pointer be aligned, in the first 16k of physical RAM and
37 * that the ATAG_CORE marker is first and present. If CONFIG_OF_FLATTREE
38 * is selected, then it will also accept a dtb pointer. Future revisions
39 * of this function may be more lenient with the physical address and
40 * may also be able to move the ATAGS block if necessary.
41 *
42 * Returns:
43 * r2 either valid atags pointer, valid dtb pointer, or zero
44 * r5, r6 corrupted
45 */
46__vet_atags:
47 tst r2, #0x3 @ aligned?
48 bne 1f
49
50 ldr r5, [r2, #0]
51#ifdef CONFIG_OF_FLATTREE
52 ldr r6, =OF_DT_MAGIC @ is it a DTB?
53 cmp r5, r6
54 beq 2f
55#endif
56 cmp r5, #ATAG_CORE_SIZE @ is first tag ATAG_CORE?
57 cmpne r5, #ATAG_CORE_SIZE_EMPTY
58 bne 1f
59 ldr r5, [r2, #4]
60 ldr r6, =ATAG_CORE
61 cmp r5, r6
62 bne 1f
63
642: mov pc, lr @ atag/dtb pointer is ok
65
661: mov r2, #0
67 mov pc, lr
68ENDPROC(__vet_atags)
69
70/*
71 * The following fragment of code is executed with the MMU on in MMU mode,
72 * and uses absolute addresses; this is not position independent.
73 *
74 * r0 = cp#15 control register
75 * r1 = machine ID
76 * r2 = atags/dtb pointer
77 * r9 = processor ID
78 */
79 __INIT
80__mmap_switched:
81 adr r3, __mmap_switched_data
82
83 ldmia r3!, {r4, r5, r6, r7}
84 cmp r4, r5 @ Copy data segment if needed
851: cmpne r5, r6
86 ldrne fp, [r4], #4
87 strne fp, [r5], #4
88 bne 1b
89
90 mov fp, #0 @ Clear BSS (and zero fp)
911: cmp r6, r7
92 strcc fp, [r6],#4
93 bcc 1b
94
95 ARM( ldmia r3, {r4, r5, r6, r7, sp})
96 THUMB( ldmia r3, {r4, r5, r6, r7} )
97 THUMB( ldr sp, [r3, #16] )
98 str r9, [r4] @ Save processor ID
99 str r1, [r5] @ Save machine type
100 str r2, [r6] @ Save atags pointer
101 cmp r7, #0
102 bicne r4, r0, #CR_A @ Clear 'A' bit
103 stmneia r7, {r0, r4} @ Save control register values
104 b start_kernel
105ENDPROC(__mmap_switched)
106
107 .align 2
108 .type __mmap_switched_data, %object
109__mmap_switched_data:
110 .long __data_loc @ r4
111 .long _sdata @ r5
112 .long __bss_start @ r6
113 .long _end @ r7
114 .long processor_id @ r4
115 .long __machine_arch_type @ r5
116 .long __atags_pointer @ r6
117#ifdef CONFIG_CPU_CP15
118 .long cr_alignment @ r7
119#else
120 .long 0 @ r7
121#endif
122 .long init_thread_union + THREAD_START_SP @ sp
123 .size __mmap_switched_data, . - __mmap_switched_data
124
125/*
126 * This provides a C-API version of __lookup_processor_type
127 */
128ENTRY(lookup_processor_type)
129 stmfd sp!, {r4 - r6, r9, lr}
130 mov r9, r0
131 bl __lookup_processor_type
132 mov r0, r5
133 ldmfd sp!, {r4 - r6, r9, pc}
134ENDPROC(lookup_processor_type)
135
136 __FINIT
137 .text
138
139/*
140 * Read processor ID register (CP#15, CR0), and look up in the linker-built
141 * supported processor list. Note that we can't use the absolute addresses
142 * for the __proc_info lists since we aren't running with the MMU on
143 * (and therefore, we are not in the correct address space). We have to
144 * calculate the offset.
145 *
146 * r9 = cpuid
147 * Returns:
148 * r3, r4, r6 corrupted
149 * r5 = proc_info pointer in physical address space
150 * r9 = cpuid (preserved)
151 */
152__lookup_processor_type:
153 adr r3, __lookup_processor_type_data
154 ldmia r3, {r4 - r6}
155 sub r3, r3, r4 @ get offset between virt&phys
156 add r5, r5, r3 @ convert virt addresses to
157 add r6, r6, r3 @ physical address space
1581: ldmia r5, {r3, r4} @ value, mask
159 and r4, r4, r9 @ mask wanted bits
160 teq r3, r4
161 beq 2f
162 add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
163 cmp r5, r6
164 blo 1b
165 mov r5, #0 @ unknown processor
1662: mov pc, lr
167ENDPROC(__lookup_processor_type)
168
169/*
170 * Look in <asm/procinfo.h> for information about the __proc_info structure.
171 */
172 .align 2
173 .type __lookup_processor_type_data, %object
174__lookup_processor_type_data:
175 .long .
176 .long __proc_info_begin
177 .long __proc_info_end
178 .size __lookup_processor_type_data, . - __lookup_processor_type_data
179
180__error_lpae:
181#ifdef CONFIG_DEBUG_LL
182 adr r0, str_lpae
183 bl printascii
184 b __error
185str_lpae: .asciz "\nError: Kernel with LPAE support, but CPU does not support LPAE.\n"
186#else
187 b __error
188#endif
189 .align
190ENDPROC(__error_lpae)
191
192__error_p:
193#ifdef CONFIG_DEBUG_LL
194 adr r0, str_p1
195 bl printascii
196 mov r0, r9
197 bl printhex8
198 adr r0, str_p2
199 bl printascii
200 b __error
201str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x"
202str_p2: .asciz ").\n"
203 .align
204#endif
205ENDPROC(__error_p)
206
207__error:
208#ifdef CONFIG_ARCH_RPC
209/*
210 * Turn the screen red on a error - RiscPC only.
211 */
212 mov r0, #0x02000000
213 mov r3, #0x11
214 orr r3, r3, r3, lsl #8
215 orr r3, r3, r3, lsl #16
216 str r3, [r0], #4
217 str r3, [r0], #4
218 str r3, [r0], #4
219 str r3, [r0], #4
220#endif
2211: mov r0, r0
222 b 1b
223ENDPROC(__error)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * linux/arch/arm/kernel/head-common.S
4 *
5 * Copyright (C) 1994-2002 Russell King
6 * Copyright (c) 2003 ARM Limited
7 * All Rights Reserved
8 */
9#include <asm/assembler.h>
10
11#define ATAG_CORE 0x54410001
12#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
13#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
14
15#ifdef CONFIG_CPU_BIG_ENDIAN
16#define OF_DT_MAGIC 0xd00dfeed
17#else
18#define OF_DT_MAGIC 0xedfe0dd0 /* 0xd00dfeed in big-endian */
19#endif
20
21/*
22 * Exception handling. Something went wrong and we can't proceed. We
23 * ought to tell the user, but since we don't have any guarantee that
24 * we're even running on the right architecture, we do virtually nothing.
25 *
26 * If CONFIG_DEBUG_LL is set we try to print out something about the error
27 * and hope for the best (useful if bootloader fails to pass a proper
28 * machine ID for example).
29 */
30 __HEAD
31
32/* Determine validity of the r2 atags pointer. The heuristic requires
33 * that the pointer be aligned, in the first 16k of physical RAM and
34 * that the ATAG_CORE marker is first and present. If CONFIG_OF_FLATTREE
35 * is selected, then it will also accept a dtb pointer. Future revisions
36 * of this function may be more lenient with the physical address and
37 * may also be able to move the ATAGS block if necessary.
38 *
39 * Returns:
40 * r2 either valid atags pointer, valid dtb pointer, or zero
41 * r5, r6 corrupted
42 */
43__vet_atags:
44 tst r2, #0x3 @ aligned?
45 bne 1f
46
47 ldr r5, [r2, #0]
48#ifdef CONFIG_OF_FLATTREE
49 ldr r6, =OF_DT_MAGIC @ is it a DTB?
50 cmp r5, r6
51 beq 2f
52#endif
53 cmp r5, #ATAG_CORE_SIZE @ is first tag ATAG_CORE?
54 cmpne r5, #ATAG_CORE_SIZE_EMPTY
55 bne 1f
56 ldr r5, [r2, #4]
57 ldr r6, =ATAG_CORE
58 cmp r5, r6
59 bne 1f
60
612: ret lr @ atag/dtb pointer is ok
62
631: mov r2, #0
64 ret lr
65ENDPROC(__vet_atags)
66
67/*
68 * The following fragment of code is executed with the MMU on in MMU mode,
69 * and uses absolute addresses; this is not position independent.
70 *
71 * r0 = cp#15 control register (exc_ret for M-class)
72 * r1 = machine ID
73 * r2 = atags/dtb pointer
74 * r9 = processor ID
75 */
76 __INIT
77__mmap_switched:
78
79 mov r7, r1
80 mov r8, r2
81 mov r10, r0
82
83 adr r4, __mmap_switched_data
84 mov fp, #0
85
86#if defined(CONFIG_XIP_DEFLATED_DATA)
87 ARM( ldr sp, [r4], #4 )
88 THUMB( ldr sp, [r4] )
89 THUMB( add r4, #4 )
90 bl __inflate_kernel_data @ decompress .data to RAM
91 teq r0, #0
92 bne __error
93#elif defined(CONFIG_XIP_KERNEL)
94 ARM( ldmia r4!, {r0, r1, r2, sp} )
95 THUMB( ldmia r4!, {r0, r1, r2, r3} )
96 THUMB( mov sp, r3 )
97 sub r2, r2, r1
98 bl memcpy @ copy .data to RAM
99#endif
100
101 ARM( ldmia r4!, {r0, r1, sp} )
102 THUMB( ldmia r4!, {r0, r1, r3} )
103 THUMB( mov sp, r3 )
104 sub r2, r1, r0
105 mov r1, #0
106 bl memset @ clear .bss
107
108 ldmia r4, {r0, r1, r2, r3}
109 str r9, [r0] @ Save processor ID
110 str r7, [r1] @ Save machine type
111 str r8, [r2] @ Save atags pointer
112 cmp r3, #0
113 strne r10, [r3] @ Save control register values
114 mov lr, #0
115 b start_kernel
116ENDPROC(__mmap_switched)
117
118 .align 2
119 .type __mmap_switched_data, %object
120__mmap_switched_data:
121#ifdef CONFIG_XIP_KERNEL
122#ifndef CONFIG_XIP_DEFLATED_DATA
123 .long _sdata @ r0
124 .long __data_loc @ r1
125 .long _edata_loc @ r2
126#endif
127 .long __bss_stop @ sp (temporary stack in .bss)
128#endif
129
130 .long __bss_start @ r0
131 .long __bss_stop @ r1
132 .long init_thread_union + THREAD_START_SP @ sp
133
134 .long processor_id @ r0
135 .long __machine_arch_type @ r1
136 .long __atags_pointer @ r2
137#ifdef CONFIG_CPU_CP15
138 .long cr_alignment @ r3
139#else
140M_CLASS(.long exc_ret) @ r3
141AR_CLASS(.long 0) @ r3
142#endif
143 .size __mmap_switched_data, . - __mmap_switched_data
144
145 __FINIT
146 .text
147
148/*
149 * This provides a C-API version of __lookup_processor_type
150 */
151ENTRY(lookup_processor_type)
152 stmfd sp!, {r4 - r6, r9, lr}
153 mov r9, r0
154 bl __lookup_processor_type
155 mov r0, r5
156 ldmfd sp!, {r4 - r6, r9, pc}
157ENDPROC(lookup_processor_type)
158
159/*
160 * Read processor ID register (CP#15, CR0), and look up in the linker-built
161 * supported processor list. Note that we can't use the absolute addresses
162 * for the __proc_info lists since we aren't running with the MMU on
163 * (and therefore, we are not in the correct address space). We have to
164 * calculate the offset.
165 *
166 * r9 = cpuid
167 * Returns:
168 * r3, r4, r6 corrupted
169 * r5 = proc_info pointer in physical address space
170 * r9 = cpuid (preserved)
171 */
172__lookup_processor_type:
173 adr r3, __lookup_processor_type_data
174 ldmia r3, {r4 - r6}
175 sub r3, r3, r4 @ get offset between virt&phys
176 add r5, r5, r3 @ convert virt addresses to
177 add r6, r6, r3 @ physical address space
1781: ldmia r5, {r3, r4} @ value, mask
179 and r4, r4, r9 @ mask wanted bits
180 teq r3, r4
181 beq 2f
182 add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
183 cmp r5, r6
184 blo 1b
185 mov r5, #0 @ unknown processor
1862: ret lr
187ENDPROC(__lookup_processor_type)
188
189/*
190 * Look in <asm/procinfo.h> for information about the __proc_info structure.
191 */
192 .align 2
193 .type __lookup_processor_type_data, %object
194__lookup_processor_type_data:
195 .long .
196 .long __proc_info_begin
197 .long __proc_info_end
198 .size __lookup_processor_type_data, . - __lookup_processor_type_data
199
200__error_lpae:
201#ifdef CONFIG_DEBUG_LL
202 adr r0, str_lpae
203 bl printascii
204 b __error
205str_lpae: .asciz "\nError: Kernel with LPAE support, but CPU does not support LPAE.\n"
206#else
207 b __error
208#endif
209 .align
210ENDPROC(__error_lpae)
211
212__error_p:
213#ifdef CONFIG_DEBUG_LL
214 adr r0, str_p1
215 bl printascii
216 mov r0, r9
217 bl printhex8
218 adr r0, str_p2
219 bl printascii
220 b __error
221str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x"
222str_p2: .asciz ").\n"
223 .align
224#endif
225ENDPROC(__error_p)
226
227__error:
228#ifdef CONFIG_ARCH_RPC
229/*
230 * Turn the screen red on a error - RiscPC only.
231 */
232 mov r0, #0x02000000
233 mov r3, #0x11
234 orr r3, r3, r3, lsl #8
235 orr r3, r3, r3, lsl #16
236 str r3, [r0], #4
237 str r3, [r0], #4
238 str r3, [r0], #4
239 str r3, [r0], #4
240#endif
2411: mov r0, r0
242 b 1b
243ENDPROC(__error)