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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>
317 palkovsky 32
#include <arch/context_offset.h>
2607 jermar 33
#include <arch/stack.h>
3922 decky 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
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#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)
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	sw $a1, EOFFSET_A1(\r)
60
	sw $a2, EOFFSET_A2(\r)
61
	sw $a3, EOFFSET_A3(\r)
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	sw $t0, EOFFSET_T0(\r)
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	sw $t1, EOFFSET_T1(\r)
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	sw $t2, EOFFSET_T2(\r)
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	sw $t3, EOFFSET_T3(\r)
66
	sw $t4, EOFFSET_T4(\r)
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	sw $t5, EOFFSET_T5(\r)
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	sw $t6, EOFFSET_T6(\r)
69
	sw $t7, EOFFSET_T7(\r)
70
	sw $t8, EOFFSET_T8(\r)
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	sw $t9, EOFFSET_T9(\r)
313 palkovsky 72
 
73
	mflo $at
74
	sw $at, EOFFSET_LO(\r)
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	mfhi $at
76
	sw $at, EOFFSET_HI(\r)
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2607 jermar 78
	sw $gp, EOFFSET_GP(\r)
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	sw $ra, EOFFSET_RA(\r)
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	sw $k1, EOFFSET_K1(\r)
313 palkovsky 81
 
1096 palkovsky 82
	mfc0 $t0, $status
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	mfc0 $t1, $epc
84
 
2607 jermar 85
	and $t2, $t0, REG_SAVE_MASK	# Save only KSU,EXL,ERL,IE
1096 palkovsky 86
	li $t3, ~(0x1f)
2607 jermar 87
	and $t0, $t0, $t3		# Clear KSU,EXL,ERL,IE
1096 palkovsky 88
 
89
	sw $t2,EOFFSET_STATUS(\r)
90
	sw $t1,EOFFSET_EPC(\r)
91
	mtc0 $t0, $status
306 palkovsky 92
.endm
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94
.macro REGISTERS_LOAD r
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	# Update only UM,EXR,IE from status, the rest
96
	# is controlled by OS and not bound to task
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	mfc0 $t0, $status
98
	lw $t1,EOFFSET_STATUS(\r)
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2607 jermar 100
	li $t2, ~REG_SAVE_MASK		# Mask UM,EXL,ERL,IE
1096 palkovsky 101
	and $t0, $t0, $t2
102
 
2607 jermar 103
	or $t0, $t0, $t1		# Copy UM,EXL, ERL, IE from saved status
1096 palkovsky 104
	mtc0 $t0, $status
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2607 jermar 106
	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)
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	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)
118
	lw $t6, EOFFSET_T6(\r)
119
	lw $t7, EOFFSET_T7(\r)
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	lw $t8, EOFFSET_T8(\r)
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	lw $t9, EOFFSET_T9(\r)
1094 palkovsky 122
 
2607 jermar 123
	lw $gp, EOFFSET_GP(\r)
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	lw $ra, EOFFSET_RA(\r)
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	lw $k1, EOFFSET_K1(\r)
306 palkovsky 126
 
2607 jermar 127
	lw $at, EOFFSET_LO(\r)
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	mtlo $at
2607 jermar 129
	lw $at, EOFFSET_HI(\r)
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	mthi $at
131
 
2607 jermar 132
	lw $at, EOFFSET_EPC(\r)
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	mtc0 $at, $epc
313 palkovsky 134
 
2607 jermar 135
	lw $at, EOFFSET_AT(\r)
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	lw $sp, EOFFSET_SP(\r)
306 palkovsky 137
.endm
138
 
313 palkovsky 139
# Move kernel stack pointer address to register K0
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# - if we are in user mode, load the appropriate stack
141
# address
142
.macro KERNEL_STACK_TO_K0
143
	# If we are in user mode
144
	mfc0 $k0, $status
145
	andi $k0, 0x10
306 palkovsky 146
 
313 palkovsky 147
	beq $k0, $0, 1f
148
	add $k0, $sp, 0
149
 
150
	# Move $k0 pointer to kernel stack
151
	lui $k0, %hi(supervisor_sp)
320 palkovsky 152
	ori $k0, $k0, %lo(supervisor_sp)
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	# Move $k0 (superveisor_sp)
154
	lw $k0, 0($k0)
3922 decky 155
1:
313 palkovsky 156
.endm
3922 decky 157
 
1 jermar 158
.org 0x0
306 palkovsky 159
kernel_image_start:
160
	/* Load temporary stack */
313 palkovsky 161
	lui $sp, %hi(end_stack)
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	ori $sp, $sp, %lo(end_stack)
1686 decky 163
 
3922 decky 164
	/* Not sure about this, but might
165
	   be needed for PIC code */
306 palkovsky 166
	lui $gp, 0x8000
167
 
3922 decky 168
	/* $a1 contains physical address of bootinfo_t */
1686 decky 169
 
1222 decky 170
	jal arch_pre_main
306 palkovsky 171
	nop
1222 decky 172
 
173
	j main_bsp
174
	nop
306 palkovsky 175
 
176
	.space TEMP_STACK_SIZE
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end_stack:
178
 
179
tlb_refill_entry:
180
	j tlb_refill_handler
181
	nop
182
 
183
cache_error_entry:
184
	j cache_error_handler
185
	nop
186
 
187
exception_entry:
188
	j exception_handler
3922 decky 189
	nop
190
 
313 palkovsky 191
exception_handler:
192
	KERNEL_STACK_TO_K0
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	sub $k0, REGISTER_SPACE
2607 jermar 194
	sw $sp, EOFFSET_SP($k0)
1102 palkovsky 195
	move $sp, $k0
1096 palkovsky 196
 
1102 palkovsky 197
	mfc0 $k0, $cause
1096 palkovsky 198
 
3922 decky 199
	sra $k0, $k0, 0x2    # cp0_exc_cause() part 1
200
	andi $k0, $k0, 0x1f  # cp0_exc_cause() part 2
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	sub $k0, 8           # 8 = SYSCALL
1096 palkovsky 202
 
1102 palkovsky 203
	beqz $k0, syscall_shortcut
3922 decky 204
	add $k0, 8           # Revert $k0 back to correct exc number
1096 palkovsky 205
 
1102 palkovsky 206
	REGISTERS_STORE_AND_EXC_RESET $sp
207
 
1096 palkovsky 208
	move $a1, $sp
3922 decky 209
	jal exc_dispatch     # exc_dispatch(excno, register_space)
1102 palkovsky 210
	move $a0, $k0
313 palkovsky 211
 
212
	REGISTERS_LOAD $sp
213
	# The $sp is automatically restored to former value
214
	eret
1096 palkovsky 215
 
2607 jermar 216
## Syscall entry
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#
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# Registers:
219
#
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# @param v0		Syscall number.
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# @param a0		1st argument.
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# @param a1		2nd argument.
223
# @param a2		3rd argument.
224
# @param a3		4th argument.
225
# @param t0		5th argument.
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# @param t1		6th argument.
227
#
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# @return		The return value will be stored in v0.
229
#
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#define SS_SP		EOFFSET_SP
231
#define SS_STATUS	EOFFSET_STATUS
232
#define SS_EPC		EOFFSET_EPC
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#define SS_K1		EOFFSET_K1
1100 palkovsky 234
syscall_shortcut:
1096 palkovsky 235
	# We have a lot of space on the stack, with free use
2607 jermar 236
	mfc0 $t3, $epc
237
	mfc0 $t2, $status
238
	sw $t3, SS_EPC($sp)		# Save EPC
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	sw $k1, SS_K1($sp)   		# Save k1 not saved on context switch
313 palkovsky 240
 
2607 jermar 241
	and $t4, $t2, REG_SAVE_MASK	# Save only KSU, EXL, ERL, IE
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	li $t5, ~(0x1f)
243
	and $t2, $t2, $t5		# Clear KSU, EXL, ERL
244
	ori $t2, $t2, 0x1		# Set IE
1096 palkovsky 245
 
2607 jermar 246
	sw $t4, SS_STATUS($sp)
247
	mtc0 $t2, $status
1096 palkovsky 248
 
2607 jermar 249
	#
250
	# Call the higher level system call handler
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	# We are going to reuse part of the unused exception stack frame
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	#
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	sw $t0, STACK_ARG4($sp)		# save the 5th argument on the stack
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	sw $t1, STACK_ARG5($sp)		# save the 6th argument on the stack
1096 palkovsky 255
	jal syscall_handler
2607 jermar 256
	sw $v0, STACK_ARG6($sp)		# save the syscall number on the stack
1096 palkovsky 257
 
258
	# restore status
2607 jermar 259
	mfc0 $t2, $status
260
	lw $t3, SS_STATUS($sp)
1096 palkovsky 261
 
2607 jermar 262
	# Change back to EXL = 1 (from last exception), otherwise
263
	# an interrupt could rewrite the CP0 - EPC
264
	li $t4, ~REG_SAVE_MASK		# Mask UM, EXL, ERL, IE
265
	and $t2, $t2, $t4
266
	or $t2, $t2, $t3		# Copy saved UM, EXL, ERL, IE
267
	mtc0 $t2, $status
1096 palkovsky 268
 
2607 jermar 269
	# restore epc + 4
270
	lw $t2, SS_EPC($sp)
271
	lw $k1, SS_K1($sp)
272
	addi $t2, $t2, 4
273
	mtc0 $t2, $epc
1126 palkovsky 274
 
2607 jermar 275
	lw $sp, SS_SP($sp)		# restore sp
1096 palkovsky 276
 
277
	eret
1278 palkovsky 278
 
1 jermar 279
tlb_refill_handler:
313 palkovsky 280
	KERNEL_STACK_TO_K0
281
	sub $k0, REGISTER_SPACE
1096 palkovsky 282
	REGISTERS_STORE_AND_EXC_RESET $k0
1102 palkovsky 283
	sw $sp,EOFFSET_SP($k0)
313 palkovsky 284
	add $sp, $k0, 0
125 jermar 285
 
1769 jermar 286
	jal tlb_refill
317 palkovsky 287
	add $a0, $sp, 0 
125 jermar 288
 
306 palkovsky 289
	REGISTERS_LOAD $sp
125 jermar 290
 
50 jermar 291
	eret
1 jermar 292
 
293
cache_error_handler:
313 palkovsky 294
	KERNEL_STACK_TO_K0
1102 palkovsky 295
	sub $k0, REGISTER_SPACE
296
	REGISTERS_STORE_AND_EXC_RESET $k0
297
	sw $sp,EOFFSET_SP($k0)
313 palkovsky 298
	add $sp, $k0, 0
1 jermar 299
 
50 jermar 300
	jal cache_error
1769 jermar 301
	add $a0, $sp, 0 
125 jermar 302
 
306 palkovsky 303
	REGISTERS_LOAD $sp
1 jermar 304
 
50 jermar 305
	eret
313 palkovsky 306
 
307
userspace_asm:
308
	add $sp, $a0, 0
1122 palkovsky 309
	add $v0, $a1, 0 
3222 svoboda 310
	add $t9, $a2, 0			# Set up correct entry into PIC code
311
	xor $a0, $a0, $a0		# $a0 is defined to hold pcb_ptr
312
					# set it to 0
313 palkovsky 313
	eret