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hal_kentry.S

Last change on this file was 654, checked in by alain, 5 years ago
euh...
File size: 16.5 KB

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1	/*
2	* hal_kentry.S - Interrupt / Exception / Syscall kernel entry point for MIPS32
3	*
4	* AUthors Ghassan Almaless (2007,2008,2009,2010,2011,2012)
5	* Mohamed Lamine Karaoui (2015)
6	* Alain Greiner (2016,2017,2018,2019)
7	*
8	* Copyright (c) UPMC Sorbonne Universites
9	*
10	* This file is part of ALMOS-MKH.
11	*
12	* ALMOS-MKH is free software; you can redistribute it and/or modify it
13	* under the terms of the GNU General Public License as published by
14	* the Free Software Foundation; version 2.0 of the License.
15	*
16	* ALMOS-MKH is distributed in the hope that it will be useful, but
17	* WITHOUT ANY WARRANTY; without even the implied warranty of
18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19	* General Public License for more details.
20	*
21	* You should have received a copy of the GNU General Public License
22	* along with ALMOS-MKH; if not, write to the Free Software Foundation,
23	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
24	*/
25
26	#define UZ_MODE_DEXT 0
27	#define UZ_AT 1
28	#define UZ_V0 2
29	#define UZ_V1 3
30	#define UZ_A0 4
31	#define UZ_A1 5
32	#define UZ_A2 6
33	#define UZ_A3 7
34	#define UZ_T0 8
35	#define UZ_T1 9
36	#define UZ_T2 10
37	#define UZ_T3 11
38	#define UZ_T4 12
39	#define UZ_T5 13
40	#define UZ_T6 14
41	#define UZ_T7 15
42	#define UZ_S0 16
43	#define UZ_S1 17
44	#define UZ_S2 18
45	#define UZ_S3 19
46	#define UZ_S4 20
47	#define UZ_S5 21
48	#define UZ_S6 22
49	#define UZ_S7 23
50	#define UZ_T8 24
51	#define UZ_T9 25
52
53	#define UZ_LO 26
54	#define UZ_HI 27
55
56	#define UZ_GP 28
57	#define UZ_SP 29
58	#define UZ_S8 30
59	#define UZ_RA 31
60	#define UZ_PTPR 32
61	#define UZ_EPC 33
62	#define UZ_SR 34
63	#define UZ_TH 35
64	#define UZ_CR 36
65
66	#define UZ_REGS 37
67
68	#include <kernel_config.h>
69
70	.section .kentry, "ax", @progbits
71
72	.extern hal_do_interrupt
73	.extern hal_do_exception
74	.extern hal_do_syscall
75	.extern puts
76	.extern putx
77	.extern putl
78
79	.org 0x180
80
81	.global hal_kentry_enter
82	.global hal_kentry_eret
83
84	.set noat
85	.set noreorder
86
87	#------------------------------------------------------------------------------------
88	# Kernel Entry point for Interrupt / Exception / Syscall
89	# At kernel entry, the relevant CPU, CP0, & CP2 registers are saved
90	# in a "UZONE" implemented in the calling thread kernel stack.
91	# All these registers are restored from the UZONE after the kernel
92	# completes the requested service.
93	#
94	# Implementation note: As this code can be executed when the core is already
95	# in kernel mode (after a syscall, the core must handle interrupts, or
96	# non-fatal MMU exceptions), this code implement a two slots stack of UZONE(s).
97	#------------------------------------------------------------------------------------
98
99	hal_kentry_enter:
100
101	#------------------------------------------------------------------------------------
102	# This code made the following actions:
103	# - save CP2_MMU_MODE & CP2_MMU_DEXT in $26,
104	# - set local_cxy into CP2_MMU_DEXT,
105	# - desactivate DATA MMU in CP2_MMU_MODE,
106	# - test if the core is already in kernel mode.
107
108	mfc2 $26, $1 # $26 <= CP2_MMU_MODE
109	andi $27, $26, 0xB # $27 <= code data MMU OFF
110	mtc2 $27, $1 # set data MMU OFF
111
112	mfc2 $27, $24 # $27 <= CP2_MMU_DEXT
113	sll $27, $27, 4 # $27 <= CP2_MMU_DEXT << 4
114	or $26, $26, $27 # $26 <= CP2_MMU_DEXT \| CP2_MMU_MODE
115
116	mfc0 $27, $15, 1 # $27 <= core CP0_EBASE
117	andi $27, $27, 0xFFF # $27 <= gid
118	srl $27, $27, 2 # $27 <= local_cxy
119	mtc2 $27, $24 # CP2_MMU_DEXT <= local_cxy
120
121	mfc0 $27, $12 # $27 <= CP0_SR
122	andi $27, $27, 0x10 # test User Mode bit
123	beq $27, $0, kernel_mode # jump if core already in kernel
124	nop
125
126	#------------------------------------------------------------------------------------
127	# This code is executed when the core is in user mode,
128	# to handle a syscall, an interrupt, or an exception.
129	# - copy user stack pointer in $27 to be saved in uzone.
130	# - set kernel stack pointer in $29 (kernel stack empty at firts entry).
131
132	user_mode:
133
134	move $27, $29 # $27 <= user stack pointer
135	mfc0 $29, $4, 2 # get pointer on thread descriptor from c0_th
136	addi $29, $29, CONFIG_THREAD_DESC_SIZE
137	addi $29, $29, -8 # $29 <= kernel stack pointer
138	j unified_mode
139	nop
140
141	#------------------------------------------------------------------------------------
142	# This code is executed when the core is already in kernel mode,
143	# (after a syscall), to handle an interrupt, or a non-fatal exception.
144	# - copy current kernel stack pointer in $27.
145
146	kernel_mode:
147
148	move $27, $29 # $27 <= current kernel stack pointer
149	j unified_mode
150	nop
151
152	#------------------------------------------------------------------------------------
153	# This code is executed in both modes (user or kernel).
154	# It executes the following actions:
155	# - decrement $29 to allocate an uzone in kernel stack
156	# - save GPR, CP0 and CP2 registers to uzone.
157	# - set the SR in kernel mode: IRQ disabled, clear EXL.
158	# The assumptions are:
159	# - c2_mode contains the data MMU OFF value.
160	# - $26 contains the previous c2_mode and c2_dext values.
161	# - $27 contains the previous sp value (can be usp or ksp).
162	# - $29 contains the current kernel stack pointer.
163
164	unified_mode:
165
166	addiu $29, $29, -(UZ_REGS*4) # allocate uzone in kernel stack
167
168	sw $26, (UZ_MODE_DEXT*4)($29) # save previous c2_mode and c2_dext values
169	sw $1, (UZ_AT*4)($29)
170	sw $2, (UZ_V0*4)($29)
171	sw $3, (UZ_V1*4)($29)
172	sw $4, (UZ_A0*4)($29)
173	sw $5, (UZ_A1*4)($29)
174	sw $6, (UZ_A2*4)($29)
175	sw $7, (UZ_A3*4)($29)
176	sw $8, (UZ_T0*4)($29)
177	sw $9, (UZ_T1*4)($29)
178	sw $10, (UZ_T2*4)($29)
179	sw $11, (UZ_T3*4)($29)
180	sw $12, (UZ_T4*4)($29)
181	sw $13, (UZ_T5*4)($29)
182	sw $14, (UZ_T6*4)($29)
183	sw $15, (UZ_T7*4)($29)
184	sw $16, (UZ_S0*4)($29)
185	sw $17, (UZ_S1*4)($29)
186	sw $18, (UZ_S2*4)($29)
187	sw $19, (UZ_S3*4)($29)
188	sw $20, (UZ_S4*4)($29)
189	sw $21, (UZ_S5*4)($29)
190	sw $22, (UZ_S6*4)($29)
191	sw $23, (UZ_S7*4)($29)
192	sw $24, (UZ_T8*4)($29)
193	sw $25, (UZ_T9*4)($29)
194
195	mflo $1
196	sw $1, (UZ_LO*4)($29) # save lo
197	mflo $1
198	sw $1, (UZ_HI*4)($29) # save hi
199
200	sw $28, (UZ_GP*4)($29) # save gp
201	sw $27, (UZ_SP*4)($29) # save previous sp (can be usp or ksp)
202	sw $30, (UZ_S8*4)($29) # save s8
203	sw $31, (UZ_RA*4)($29) # save ra
204
205	mfc0 $1, $14
206	sw $1, (UZ_EPC*4)($29) # save c0_epc
207	mfc0 $1, $12
208	sw $1, (UZ_SR*4)($29) # save c0_sr
209	mfc0 $1, $4, 2
210	sw $1, (UZ_TH*4)($29) # save c0_th
211	mfc0 $1, $13
212	sw $1, (UZ_CR*4)($29) # save c0_cr
213	mfc2 $1, $0
214	sw $1, (UZ_PTPR*4)($29) # save c2_ptpr
215
216
217	mfc0 $3, $12 # $3 <= c0_sr
218	srl $3, $3, 5
219	sll $3, $3, 5 # reset 5 LSB bits
220	mtc0 $3, $12 # set new c0_sr
221
222	#--------------------
223	#if DEBUG_HAL_KENTRY
224
225	# display "enter" message
226	la $4, msg_enter
227	jal puts
228	nop
229	move $4, $29
230	jal putx
231	nop
232	la $4, msg_cycle
233	jal puts
234	nop
235	jal hal_time_stamp
236	nop
237	move $4, $2
238	jal putd
239	nop
240	la $4, msg_crlf
241	jal puts
242	nop
243	# display saved CR value
244	la $4, msg_cr
245	jal puts
246	nop
247	lw $4, (UZ_CR*4)($29)
248	jal putx
249	nop
250	la $4, msg_crlf
251	jal puts
252	nop
253	# display saved SP value
254	la $4, msg_sp
255	jal puts
256	nop
257	lw $4, (UZ_SP*4)($29)
258	jal putx
259	nop
260	la $4, msg_crlf
261	jal puts
262	nop
263	# display saved RA value
264	la $4, msg_ra
265	jal puts
266	nop
267	lw $4, (UZ_RA*4)($29)
268	jal putx
269	nop
270	la $4, msg_crlf
271	jal puts
272	nop
273	# display saved TH value
274	la $4, msg_th
275	jal puts
276	nop
277	lw $4, (UZ_TH*4)($29)
278	jal putx
279	nop
280	la $4, msg_crlf
281	jal puts
282	nop
283	# display saved EPC value
284	la $4, msg_epc
285	jal puts
286	nop
287	lw $4, (UZ_EPC*4)($29)
288	jal putx
289	nop
290	la $4, msg_crlf
291	jal puts
292	nop
293	# display saved MODE & DEXT values
294	la $4, msg_mode
295	jal puts
296	nop
297	lw $4, (UZ_MODE_DEXT*4)($29)
298	jal putx
299	nop
300	la $4, msg_crlf
301	jal puts
302	nop
303	# display saved V0 value
304	la $4, msg_v0
305	jal puts
306	nop
307	lw $4, (UZ_V0*4)($29)
308	jal putx
309	nop
310	la $4, msg_crlf
311	jal puts
312	nop
313
314	#endif
315	#-----
316
317	#------------------------------------------------------------------------------------
318	# This code handle the two-slots uzone pointers stack, and calls the relevant
319	# Interrupt / Exception / Syscall handler, depending on XCODE in CP0_CR.
320	# Both the hal_do_syscall() and the hal_do_exception() functions use
321	# the values saved in the "uzone", but a syscall can be interrupted
322	# by an interrupt, or by a non-fatal exception. Therefore, we need
323	# to handle a two-slots "stack of uzones", implemented in the kernel stack,
324	# using the two "current_uzone" and "previous_uzone" pointers in thread descriptor.
325	# - at kernel_entry, we copy the "current_uzone" pointer to the "previous_uzone"
326	# slot, and copy the "$29" stack pointer to the "current_uzone" slot.
327	# - at kernel_exit, we simply restore the "previous_uzone" value to the
328	# "current_uzone" slot.
329	# For a syscall, the hal_do_syscall() function increment the uzone[EPC]
330	# slot and set the return value in the uzone[V0] slot before returning.
331
332	# update "current_uzone" and "previous_uzone" pointers
333	mfc0 $4, $4, 2 # $4 <= pointer on thread desc
334	lw $5, 8($4) # $5 <= current uzone pointer trom thread
335	sw $29, 8($4) # current uzone pointer <= $29
336	sw $5, 12($4) # previous uzone pointer <= current
337
338	# analyse XCODE to call relevant handler
339	mfc0 $17, $13 # $17 <= CR
340	andi $17, $17, 0x3F # $17 <= XCODE
341	ori $8, $0, 0x20
342	beq $8, $17, cause_sys # go to syscall handler
343	nop
344	beq $17, $0, cause_int # go to interrupt handler
345	nop
346
347	cause_excp:
348
349	jal hal_do_exception # call exception handler
350	nop
351	j kentry_exit # jump to kentry_exit
352	nop
353
354	cause_sys:
355
356	jal hal_do_syscall # call syscall handler
357	nop
358	j kentry_exit # jump to kentry_exit
359	nop
360
361	cause_int:
362
363	jal hal_do_interrupt # call interrupt handler
364	nop
365
366	# -----------------------------------------------------------------------------------
367	# Kernel exit
368	# - All registers saved in the uzone are restored, using the pointer on uzone,
369	# that is contained in $29.
370	# - The "current_uzone" pointer in thread descriptor, that has beeen modified at
371	# kernel entry is restored from value contained in the uzone[UZ_SP] slot.
372	# -----------------------------------------------------------------------------------
373
374	kentry_exit:
375
376	# restore "current_uzone" pointer
377	mfc0 $4, $4, 2 # $4 <= pointer on thread desc
378	lw $5, 12($4) # $5 <= previous uzone pointer from thread
379	sw $5, 8($4) # current uzone pointer <= previous
380
381	#-------------------
382	#if DEBUG_HAL_KENTRY
383
384	# display "exit" message
385	la $4, msg_exit
386	jal puts
387	nop
388	move $4, $29
389	jal putx
390	nop
391	la $4, msg_cycle
392	jal puts
393	nop
394	jal hal_time_stamp
395	nop
396	move $4, $2
397	jal putd
398	nop
399	la $4, msg_crlf
400	jal puts
401	nop
402	# display saved CR value
403	la $4, msg_cr
404	jal puts
405	nop
406	lw $4, (UZ_CR*4)($29)
407	jal putx
408	nop
409	la $4, msg_crlf
410	jal puts
411	nop
412	# display saved SP value
413	la $4, msg_sp
414	jal puts
415	nop
416	lw $4, (UZ_SP*4)($29)
417	jal putx
418	nop
419	la $4, msg_crlf
420	jal puts
421	nop
422	# display saved RA value
423	la $4, msg_ra
424	jal puts
425	nop
426	lw $4, (UZ_RA*4)($29)
427	jal putx
428	nop
429	la $4, msg_crlf
430	jal puts
431	nop
432	# display saved TH value
433	la $4, msg_th
434	jal puts
435	nop
436	lw $4, (UZ_TH*4)($29)
437	jal putx
438	nop
439	la $4, msg_crlf
440	jal puts
441	nop
442	# display saved EPC value
443	la $4, msg_epc
444	jal puts
445	nop
446	lw $4, (UZ_EPC*4)($29)
447	jal putx
448	nop
449	la $4, msg_crlf
450	jal puts
451	nop
452	# display saved MODE_DEXT value
453	la $4, msg_mode
454	jal puts
455	nop
456	lw $4, (UZ_MODE_DEXT*4)($29)
457	jal putx
458	nop
459	la $4, msg_crlf
460	jal puts
461	nop
462	# display saved V0 value
463	la $4, msg_v0
464	jal puts
465	nop
466	lw $4, (UZ_V0*4)($29)
467	jal putx
468	nop
469	la $4, msg_crlf
470	jal puts
471	nop
472
473	#endif
474	#-----
475
476	# restore registers from uzone
477	or $27, $0, $29 # $27 <= ksp (contains &uzone)
478
479	lw $1, (UZ_EPC*4)($27)
480	mtc0 $1, $14 # restore c0_epc from uzone
481	lw $1, (UZ_SR*4)($27)
482	mtc0 $1, $12 # restore c0_sr from uzone
483
484	lw $26, (UZ_HI*4)($27)
485	mthi $26 # restore hi from uzone
486	lw $26, (UZ_LO*4)($27)
487	mtlo $26 # restore lo from uzone
488
489	lw $1, (UZ_AT*4)($27)
490	lw $2, (UZ_V0*4)($27)
491	lw $3, (UZ_V1*4)($27)
492	lw $4, (UZ_A0*4)($27)
493	lw $5, (UZ_A1*4)($27)
494	lw $6, (UZ_A2*4)($27)
495	lw $7, (UZ_A3*4)($27)
496	lw $8, (UZ_T0*4)($27)
497	lw $9, (UZ_T1*4)($27)
498	lw $10, (UZ_T2*4)($27)
499	lw $11, (UZ_T3*4)($27)
500	lw $12, (UZ_T4*4)($27)
501	lw $13, (UZ_T5*4)($27)
502	lw $14, (UZ_T6*4)($27)
503	lw $15, (UZ_T7*4)($27)
504	lw $16, (UZ_S0*4)($27)
505	lw $17, (UZ_S1*4)($27)
506	lw $18, (UZ_S2*4)($27)
507	lw $19, (UZ_S3*4)($27)
508	lw $20, (UZ_S4*4)($27)
509	lw $21, (UZ_S5*4)($27)
510	lw $22, (UZ_S6*4)($27)
511	lw $23, (UZ_S7*4)($27)
512	lw $24, (UZ_T8*4)($27)
513	lw $25, (UZ_T9*4)($27)
514
515	lw $28, (UZ_GP*4)($27) # restore gp_28 from uzone
516	lw $29, (UZ_SP*4)($27) # restore sp_29 from uzone
517	lw $30, (UZ_S8*4)($27) # restore s8_30 from uzone
518	lw $31, (UZ_RA*4)($27) # restore ra_31 from uzone
519
520	lw $26, (UZ_MODE_DEXT*4)($27)
521	srl $27, $26, 4 # $27 <= CP2_DEXT
522	mtc2 $27, $24 # restore c2_dest from uzone
523	andi $27, $26, 0xF # $27 <= CP2_MODE
524	mtc2 $27, $1 # restore c2_mode from uzone
525
526	# -----------------------------------------------------------------------------------
527	# eret function
528	# -----------------------------------------------------------------------------------
529
530	hal_kentry_eret:
531	eret # jump to EPC, reset EXL bit
532
533	.set reorder
534	.set at
535
536	#------------------------------------------------------------------------------------
537	.section .kdata
538
539	msg_cr:
540	.align 2
541	.asciiz "- UZ_CR = "
542	msg_sp:
543	.align 2
544	.asciiz "- UZ_SP = "
545	msg_ra:
546	.align 2
547	.asciiz "- UZ_RA = "
548	msg_epc:
549	.align 2
550	.asciiz "- UZ_EPC = "
551	msg_th:
552	.align 2
553	.asciiz "- UZ_TH = "
554	msg_mode:
555	.align 2
556	.asciiz "- UZ_MODE = "
557	msg_v0:
558	.align 2
559	.asciiz "- UZ_V0 = "
560	msg_crlf:
561	.align 2
562	.asciiz "\n"
563	msg_enter:
564	.align 2
565	.asciiz "\nenter kernel : &uzone = "
566	msg_exit:
567	.align 2
568	.asciiz "\nexit kernel : &uzone = "
569	msg_cycle:
570	.align 2
571	.asciiz " / cycle = "
572

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