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308 jermar 1
#
2071 jermar 2
# Copyright (c) 2003-2004 Jakub Jermar
1 jermar 3
# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# - Redistributions of source code must retain the above copyright
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#   notice, this list of conditions and the following disclaimer.
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# - Redistributions in binary form must reproduce the above copyright
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#   notice, this list of conditions and the following disclaimer in the
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#   documentation and/or other materials provided with the distribution.
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# - The name of the author may not be used to endorse or promote products
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#   derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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306 palkovsky 29
#include <arch/asm/regname.h>
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#include <arch/mm/page.h>
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#include <arch/asm/boot.h>
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#include <arch/context_offset.h>
2607 jermar 33
#include <arch/stack.h>
306 palkovsky 34
 
1 jermar 35
.text
36
 
37
.set noat
38
.set noreorder
39
.set nomacro
40
 
41
.global kernel_image_start
42
.global tlb_refill_entry
43
.global cache_error_entry
44
.global exception_entry
313 palkovsky 45
.global userspace_asm
1 jermar 46
 
1096 palkovsky 47
# Which status bits should are thread-local
48
#define REG_SAVE_MASK 0x1f # KSU(UM), EXL, ERL, IE
49
 
313 palkovsky 50
# Save registers to space defined by \r
1096 palkovsky 51
# We will change status: Disable ERL,EXL,UM,IE
52
# These changes will be automatically reversed in REGISTER_LOAD
1102 palkovsky 53
# SP is NOT saved as part of these registers
1096 palkovsky 54
.macro REGISTERS_STORE_AND_EXC_RESET r
2607 jermar 55
	sw $at, EOFFSET_AT(\r)
56
	sw $v0, EOFFSET_V0(\r)
57
	sw $v1, EOFFSET_V1(\r)
58
	sw $a0, EOFFSET_A0(\r)
59
	sw $a1, EOFFSET_A1(\r)
60
	sw $a2, EOFFSET_A2(\r)
61
	sw $a3, EOFFSET_A3(\r)
62
	sw $t0, EOFFSET_T0(\r)
63
	sw $t1, EOFFSET_T1(\r)
64
	sw $t2, EOFFSET_T2(\r)
65
	sw $t3, EOFFSET_T3(\r)
66
	sw $t4, EOFFSET_T4(\r)
67
	sw $t5, EOFFSET_T5(\r)
68
	sw $t6, EOFFSET_T6(\r)
69
	sw $t7, EOFFSET_T7(\r)
70
	sw $t8, EOFFSET_T8(\r)
71
	sw $t9, EOFFSET_T9(\r)
313 palkovsky 72
 
73
	mflo $at
74
	sw $at, EOFFSET_LO(\r)
75
	mfhi $at
76
	sw $at, EOFFSET_HI(\r)
77
 
1094 palkovsky 78
#ifdef CONFIG_DEBUG_ALLREGS	
2607 jermar 79
	sw $s0, EOFFSET_S0(\r)
80
	sw $s1, EOFFSET_S1(\r)
81
	sw $s2, EOFFSET_S2(\r)
82
	sw $s3, EOFFSET_S3(\r)
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	sw $s4, EOFFSET_S4(\r)
84
	sw $s5, EOFFSET_S5(\r)
85
	sw $s6, EOFFSET_S6(\r)
86
	sw $s7, EOFFSET_S7(\r)
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	sw $s8, EOFFSET_S8(\r)
1094 palkovsky 88
#endif
89
 
2607 jermar 90
	sw $gp, EOFFSET_GP(\r)
91
	sw $ra, EOFFSET_RA(\r)
92
	sw $k1, EOFFSET_K1(\r)
313 palkovsky 93
 
1096 palkovsky 94
	mfc0 $t0, $status
95
	mfc0 $t1, $epc
96
 
2607 jermar 97
	and $t2, $t0, REG_SAVE_MASK	# Save only KSU,EXL,ERL,IE
1096 palkovsky 98
	li $t3, ~(0x1f)
2607 jermar 99
	and $t0, $t0, $t3		# Clear KSU,EXL,ERL,IE
1096 palkovsky 100
 
101
	sw $t2,EOFFSET_STATUS(\r)
102
	sw $t1,EOFFSET_EPC(\r)
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	mtc0 $t0, $status
306 palkovsky 104
.endm
105
 
106
.macro REGISTERS_LOAD r
1096 palkovsky 107
	# Update only UM,EXR,IE from status, the rest
108
	# is controlled by OS and not bound to task
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	mfc0 $t0, $status
110
	lw $t1,EOFFSET_STATUS(\r)
111
 
2607 jermar 112
	li $t2, ~REG_SAVE_MASK		# Mask UM,EXL,ERL,IE
1096 palkovsky 113
	and $t0, $t0, $t2
114
 
2607 jermar 115
	or $t0, $t0, $t1		# Copy UM,EXL, ERL, IE from saved status
1096 palkovsky 116
	mtc0 $t0, $status
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2607 jermar 118
	lw $v0, EOFFSET_V0(\r)
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	lw $v1, EOFFSET_V1(\r)
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	lw $a0, EOFFSET_A0(\r)
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	lw $a1, EOFFSET_A1(\r)
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	lw $a2, EOFFSET_A2(\r)
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	lw $a3, EOFFSET_A3(\r)
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	lw $t0, EOFFSET_T0(\r)
125
	lw $t1, EOFFSET_T1(\r)
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	lw $t2, EOFFSET_T2(\r)
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	lw $t3, EOFFSET_T3(\r)
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	lw $t4, EOFFSET_T4(\r)
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	lw $t5, EOFFSET_T5(\r)
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	lw $t6, EOFFSET_T6(\r)
131
	lw $t7, EOFFSET_T7(\r)
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	lw $t8, EOFFSET_T8(\r)
133
	lw $t9, EOFFSET_T9(\r)
1094 palkovsky 134
 
135
#ifdef CONFIG_DEBUG_ALLREGS	
2607 jermar 136
	lw $s0, EOFFSET_S0(\r)
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	lw $s1, EOFFSET_S1(\r)
138
	lw $s2, EOFFSET_S2(\r)
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	lw $s3, EOFFSET_S3(\r)
140
	lw $s4, EOFFSET_S4(\r)
141
	lw $s5, EOFFSET_S5(\r)
142
	lw $s6, EOFFSET_S6(\r)
143
	lw $s7, EOFFSET_S7(\r)
144
	lw $s8, EOFFSET_S8(\r)
1094 palkovsky 145
#endif
2607 jermar 146
	lw $gp, EOFFSET_GP(\r)
147
	lw $ra, EOFFSET_RA(\r)
148
	lw $k1, EOFFSET_K1(\r)
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2607 jermar 150
	lw $at, EOFFSET_LO(\r)
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	mtlo $at
2607 jermar 152
	lw $at, EOFFSET_HI(\r)
313 palkovsky 153
	mthi $at
154
 
2607 jermar 155
	lw $at, EOFFSET_EPC(\r)
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	mtc0 $at, $epc
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2607 jermar 158
	lw $at, EOFFSET_AT(\r)
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	lw $sp, EOFFSET_SP(\r)
306 palkovsky 160
.endm
161
 
313 palkovsky 162
# Move kernel stack pointer address to register K0
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# - if we are in user mode, load the appropriate stack
164
# address
165
.macro KERNEL_STACK_TO_K0
166
	# If we are in user mode
167
	mfc0 $k0, $status
168
	andi $k0, 0x10
306 palkovsky 169
 
313 palkovsky 170
	beq $k0, $0, 1f
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	add $k0, $sp, 0
172
 
173
	# Move $k0 pointer to kernel stack
174
	lui $k0, %hi(supervisor_sp)
320 palkovsky 175
	ori $k0, $k0, %lo(supervisor_sp)
313 palkovsky 176
	# Move $k0 (superveisor_sp)
177
	lw $k0, 0($k0)
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1:		
179
.endm
180
 
1 jermar 181
.org 0x0
306 palkovsky 182
kernel_image_start:
183
	/* Load temporary stack */
313 palkovsky 184
	lui $sp, %hi(end_stack)
320 palkovsky 185
	ori $sp, $sp, %lo(end_stack)
1686 decky 186
 
187
	/* $a1 contains physical address of bootinfo_t */
188
	/* $a2 contains size of bootinfo_t */
189
 
190
	beq $a2, $0, bootinfo_end
191
 
306 palkovsky 192
	/* Not sure about this, but might be needed for PIC code???? */
193
	lui $gp, 0x8000
194
 
1686 decky 195
	lui $a3, %hi(bootinfo)
196
	ori $a3, $a3, %lo(bootinfo)
197
 
198
	bootinfo_loop:
199
 
200
		lw $v0, 0($a1)
201
		sw $v0, 0($a3)
202
 
203
		addi $a1, $a1, 4
204
		addi $a3, $a3, 4
205
		addi $a2, $a2, -4
206
 
207
		bgtz $a2, bootinfo_loop
208
		nop
209
 
210
	bootinfo_end:
211
 
1222 decky 212
	jal arch_pre_main
306 palkovsky 213
	nop
1222 decky 214
 
215
	j main_bsp
216
	nop
306 palkovsky 217
 
218
	.space TEMP_STACK_SIZE
326 palkovsky 219
end_stack:
220
 
221
tlb_refill_entry:
222
	j tlb_refill_handler
223
	nop
224
 
225
cache_error_entry:
226
	j cache_error_handler
227
	nop
228
 
229
exception_entry:
230
	j exception_handler
231
	nop	
306 palkovsky 232
 
313 palkovsky 233
exception_handler:
234
	KERNEL_STACK_TO_K0
235
	sub $k0, REGISTER_SPACE
2607 jermar 236
	sw $sp, EOFFSET_SP($k0)
1102 palkovsky 237
	move $sp, $k0
1096 palkovsky 238
 
1102 palkovsky 239
	mfc0 $k0, $cause
1096 palkovsky 240
 
2607 jermar 241
	sra $k0, $k0, 0x2		# cp0_exc_cause() part 1
242
	andi $k0, $k0, 0x1f		# cp0_exc_cause() part 2
243
	sub $k0, 8			# 8 = SYSCALL
1096 palkovsky 244
 
1102 palkovsky 245
	beqz $k0, syscall_shortcut
2607 jermar 246
	add $k0, 8			# Revert $k0 back to correct exc number
1096 palkovsky 247
 
1102 palkovsky 248
	REGISTERS_STORE_AND_EXC_RESET $sp
249
 
1096 palkovsky 250
	move $a1, $sp
2607 jermar 251
	jal exc_dispatch		# exc_dispatch(excno, register_space)
1102 palkovsky 252
	move $a0, $k0
313 palkovsky 253
 
254
	REGISTERS_LOAD $sp
255
	# The $sp is automatically restored to former value
256
	eret
1096 palkovsky 257
 
2607 jermar 258
## Syscall entry
259
#
260
# Registers:
261
#
262
# @param v0		Syscall number.
263
# @param a0		1st argument.
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# @param a1		2nd argument.
265
# @param a2		3rd argument.
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# @param a3		4th argument.
267
# @param t0		5th argument.
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# @param t1		6th argument.
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#
270
# @return		The return value will be stored in v0.
271
#
272
#define SS_SP		EOFFSET_SP
273
#define SS_STATUS	EOFFSET_STATUS
274
#define SS_EPC		EOFFSET_EPC
275
#define SS_K1		EOFFSET_K1
1100 palkovsky 276
syscall_shortcut:
1096 palkovsky 277
	# We have a lot of space on the stack, with free use
2607 jermar 278
	mfc0 $t3, $epc
279
	mfc0 $t2, $status
280
	sw $t3, SS_EPC($sp)		# Save EPC
281
	sw $k1, SS_K1($sp)   		# Save k1 not saved on context switch
313 palkovsky 282
 
2607 jermar 283
	and $t4, $t2, REG_SAVE_MASK	# Save only KSU, EXL, ERL, IE
284
	li $t5, ~(0x1f)
285
	and $t2, $t2, $t5		# Clear KSU, EXL, ERL
286
	ori $t2, $t2, 0x1		# Set IE
1096 palkovsky 287
 
2607 jermar 288
	sw $t4, SS_STATUS($sp)
289
	mtc0 $t2, $status
1096 palkovsky 290
 
2607 jermar 291
	#
292
	# Call the higher level system call handler
293
	# We are going to reuse part of the unused exception stack frame
294
	#
295
	sw $t0, STACK_ARG4($sp)		# save the 5th argument on the stack
296
	sw $t1, STACK_ARG5($sp)		# save the 6th argument on the stack
1096 palkovsky 297
	jal syscall_handler
2607 jermar 298
	sw $v0, STACK_ARG6($sp)		# save the syscall number on the stack
1096 palkovsky 299
 
300
	# restore status
2607 jermar 301
	mfc0 $t2, $status
302
	lw $t3, SS_STATUS($sp)
1096 palkovsky 303
 
2607 jermar 304
	# Change back to EXL = 1 (from last exception), otherwise
305
	# an interrupt could rewrite the CP0 - EPC
306
	li $t4, ~REG_SAVE_MASK		# Mask UM, EXL, ERL, IE
307
	and $t2, $t2, $t4
308
	or $t2, $t2, $t3		# Copy saved UM, EXL, ERL, IE
309
	mtc0 $t2, $status
1096 palkovsky 310
 
2607 jermar 311
	# restore epc + 4
312
	lw $t2, SS_EPC($sp)
313
	lw $k1, SS_K1($sp)
314
	addi $t2, $t2, 4
315
	mtc0 $t2, $epc
1126 palkovsky 316
 
2607 jermar 317
	lw $sp, SS_SP($sp)		# restore sp
1096 palkovsky 318
 
319
	eret
1278 palkovsky 320
 
1 jermar 321
tlb_refill_handler:
313 palkovsky 322
	KERNEL_STACK_TO_K0
323
	sub $k0, REGISTER_SPACE
1096 palkovsky 324
	REGISTERS_STORE_AND_EXC_RESET $k0
1102 palkovsky 325
	sw $sp,EOFFSET_SP($k0)
313 palkovsky 326
	add $sp, $k0, 0
125 jermar 327
 
1769 jermar 328
	jal tlb_refill
317 palkovsky 329
	add $a0, $sp, 0 
125 jermar 330
 
306 palkovsky 331
	REGISTERS_LOAD $sp
125 jermar 332
 
50 jermar 333
	eret
1 jermar 334
 
335
cache_error_handler:
313 palkovsky 336
	KERNEL_STACK_TO_K0
1102 palkovsky 337
	sub $k0, REGISTER_SPACE
338
	REGISTERS_STORE_AND_EXC_RESET $k0
339
	sw $sp,EOFFSET_SP($k0)
313 palkovsky 340
	add $sp, $k0, 0
1 jermar 341
 
50 jermar 342
	jal cache_error
1769 jermar 343
	add $a0, $sp, 0 
125 jermar 344
 
306 palkovsky 345
	REGISTERS_LOAD $sp
1 jermar 346
 
50 jermar 347
	eret
313 palkovsky 348
 
349
userspace_asm:
350
	add $sp, $a0, 0
1122 palkovsky 351
	add $v0, $a1, 0 
2607 jermar 352
	add $t9, $a2, 0			# Set up correct entry into PIC code 
313 palkovsky 353
	eret