xref: /openbmc/linux/arch/mips/kernel/genex.S (revision 791d3ef2) 
1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 1994 - 2000, 2001, 2003 Ralf Baechle
7 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
8 * Copyright (C) 2002, 2007  Maciej W. Rozycki
9 * Copyright (C) 2001, 2012 MIPS Technologies, Inc.  All rights reserved.
10 */
11#include <linux/init.h>
12
13#include <asm/asm.h>
14#include <asm/asmmacro.h>
15#include <asm/cacheops.h>
16#include <asm/irqflags.h>
17#include <asm/regdef.h>
18#include <asm/fpregdef.h>
19#include <asm/mipsregs.h>
20#include <asm/stackframe.h>
21#include <asm/war.h>
22#include <asm/thread_info.h>
23
24	__INIT
25
26/*
27 * General exception vector for all other CPUs.
28 *
29 * Be careful when changing this, it has to be at most 128 bytes
30 * to fit into space reserved for the exception handler.
31 */
32NESTED(except_vec3_generic, 0, sp)
33	.set	push
34	.set	noat
35#if R5432_CP0_INTERRUPT_WAR
36	mfc0	k0, CP0_INDEX
37#endif
38	mfc0	k1, CP0_CAUSE
39	andi	k1, k1, 0x7c
40#ifdef CONFIG_64BIT
41	dsll	k1, k1, 1
42#endif
43	PTR_L	k0, exception_handlers(k1)
44	jr	k0
45	.set	pop
46	END(except_vec3_generic)
47
48/*
49 * General exception handler for CPUs with virtual coherency exception.
50 *
51 * Be careful when changing this, it has to be at most 256 (as a special
52 * exception) bytes to fit into space reserved for the exception handler.
53 */
54NESTED(except_vec3_r4000, 0, sp)
55	.set	push
56	.set	arch=r4000
57	.set	noat
58	mfc0	k1, CP0_CAUSE
59	li	k0, 31<<2
60	andi	k1, k1, 0x7c
61	.set	push
62	.set	noreorder
63	.set	nomacro
64	beq	k1, k0, handle_vced
65	 li	k0, 14<<2
66	beq	k1, k0, handle_vcei
67#ifdef CONFIG_64BIT
68	 dsll	k1, k1, 1
69#endif
70	.set	pop
71	PTR_L	k0, exception_handlers(k1)
72	jr	k0
73
74	/*
75	 * Big shit, we now may have two dirty primary cache lines for the same
76	 * physical address.  We can safely invalidate the line pointed to by
77	 * c0_badvaddr because after return from this exception handler the
78	 * load / store will be re-executed.
79	 */
80handle_vced:
81	MFC0	k0, CP0_BADVADDR
82	li	k1, -4					# Is this ...
83	and	k0, k1					# ... really needed?
84	mtc0	zero, CP0_TAGLO
85	cache	Index_Store_Tag_D, (k0)
86	cache	Hit_Writeback_Inv_SD, (k0)
87#ifdef CONFIG_PROC_FS
88	PTR_LA	k0, vced_count
89	lw	k1, (k0)
90	addiu	k1, 1
91	sw	k1, (k0)
92#endif
93	eret
94
95handle_vcei:
96	MFC0	k0, CP0_BADVADDR
97	cache	Hit_Writeback_Inv_SD, (k0)		# also cleans pi
98#ifdef CONFIG_PROC_FS
99	PTR_LA	k0, vcei_count
100	lw	k1, (k0)
101	addiu	k1, 1
102	sw	k1, (k0)
103#endif
104	eret
105	.set	pop
106	END(except_vec3_r4000)
107
108	__FINIT
109
110	.align	5	/* 32 byte rollback region */
111LEAF(__r4k_wait)
112	.set	push
113	.set	noreorder
114	/* start of rollback region */
115	LONG_L	t0, TI_FLAGS($28)
116	nop
117	andi	t0, _TIF_NEED_RESCHED
118	bnez	t0, 1f
119	 nop
120	nop
121	nop
122#ifdef CONFIG_CPU_MICROMIPS
123	nop
124	nop
125	nop
126	nop
127#endif
128	.set	MIPS_ISA_ARCH_LEVEL_RAW
129	wait
130	/* end of rollback region (the region size must be power of two) */
1311:
132	jr	ra
133	 nop
134	.set	pop
135	END(__r4k_wait)
136
137	.macro	BUILD_ROLLBACK_PROLOGUE handler
138	FEXPORT(rollback_\handler)
139	.set	push
140	.set	noat
141	MFC0	k0, CP0_EPC
142	PTR_LA	k1, __r4k_wait
143	ori	k0, 0x1f	/* 32 byte rollback region */
144	xori	k0, 0x1f
145	bne	k0, k1, \handler
146	MTC0	k0, CP0_EPC
147	.set pop
148	.endm
149
150	.align	5
151BUILD_ROLLBACK_PROLOGUE handle_int
152NESTED(handle_int, PT_SIZE, sp)
153	.cfi_signal_frame
154#ifdef CONFIG_TRACE_IRQFLAGS
155	/*
156	 * Check to see if the interrupted code has just disabled
157	 * interrupts and ignore this interrupt for now if so.
158	 *
159	 * local_irq_disable() disables interrupts and then calls
160	 * trace_hardirqs_off() to track the state. If an interrupt is taken
161	 * after interrupts are disabled but before the state is updated
162	 * it will appear to restore_all that it is incorrectly returning with
163	 * interrupts disabled
164	 */
165	.set	push
166	.set	noat
167	mfc0	k0, CP0_STATUS
168#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
169	and	k0, ST0_IEP
170	bnez	k0, 1f
171
172	mfc0	k0, CP0_EPC
173	.set	noreorder
174	j	k0
175	 rfe
176#else
177	and	k0, ST0_IE
178	bnez	k0, 1f
179
180	eret
181#endif
1821:
183	.set pop
184#endif
185	SAVE_ALL docfi=1
186	CLI
187	TRACE_IRQS_OFF
188
189	LONG_L	s0, TI_REGS($28)
190	LONG_S	sp, TI_REGS($28)
191
192	/*
193	 * SAVE_ALL ensures we are using a valid kernel stack for the thread.
194	 * Check if we are already using the IRQ stack.
195	 */
196	move	s1, sp # Preserve the sp
197
198	/* Get IRQ stack for this CPU */
199	ASM_CPUID_MFC0	k0, ASM_SMP_CPUID_REG
200#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
201	lui	k1, %hi(irq_stack)
202#else
203	lui	k1, %highest(irq_stack)
204	daddiu	k1, %higher(irq_stack)
205	dsll	k1, 16
206	daddiu	k1, %hi(irq_stack)
207	dsll	k1, 16
208#endif
209	LONG_SRL	k0, SMP_CPUID_PTRSHIFT
210	LONG_ADDU	k1, k0
211	LONG_L	t0, %lo(irq_stack)(k1)
212
213	# Check if already on IRQ stack
214	PTR_LI	t1, ~(_THREAD_SIZE-1)
215	and	t1, t1, sp
216	beq	t0, t1, 2f
217
218	/* Switch to IRQ stack */
219	li	t1, _IRQ_STACK_START
220	PTR_ADD sp, t0, t1
221
222	/* Save task's sp on IRQ stack so that unwinding can follow it */
223	LONG_S	s1, 0(sp)
2242:
225	jal	plat_irq_dispatch
226
227	/* Restore sp */
228	move	sp, s1
229
230	j	ret_from_irq
231#ifdef CONFIG_CPU_MICROMIPS
232	nop
233#endif
234	END(handle_int)
235
236	__INIT
237
238/*
239 * Special interrupt vector for MIPS64 ISA & embedded MIPS processors.
240 * This is a dedicated interrupt exception vector which reduces the
241 * interrupt processing overhead.  The jump instruction will be replaced
242 * at the initialization time.
243 *
244 * Be careful when changing this, it has to be at most 128 bytes
245 * to fit into space reserved for the exception handler.
246 */
247NESTED(except_vec4, 0, sp)
2481:	j	1b			/* Dummy, will be replaced */
249	END(except_vec4)
250
251/*
252 * EJTAG debug exception handler.
253 * The EJTAG debug exception entry point is 0xbfc00480, which
254 * normally is in the boot PROM, so the boot PROM must do an
255 * unconditional jump to this vector.
256 */
257NESTED(except_vec_ejtag_debug, 0, sp)
258	j	ejtag_debug_handler
259#ifdef CONFIG_CPU_MICROMIPS
260	 nop
261#endif
262	END(except_vec_ejtag_debug)
263
264	__FINIT
265
266/*
267 * Vectored interrupt handler.
268 * This prototype is copied to ebase + n*IntCtl.VS and patched
269 * to invoke the handler
270 */
271BUILD_ROLLBACK_PROLOGUE except_vec_vi
272NESTED(except_vec_vi, 0, sp)
273	SAVE_SOME docfi=1
274	SAVE_AT docfi=1
275	.set	push
276	.set	noreorder
277	PTR_LA	v1, except_vec_vi_handler
278FEXPORT(except_vec_vi_lui)
279	lui	v0, 0		/* Patched */
280	jr	v1
281FEXPORT(except_vec_vi_ori)
282	 ori	v0, 0		/* Patched */
283	.set	pop
284	END(except_vec_vi)
285EXPORT(except_vec_vi_end)
286
287/*
288 * Common Vectored Interrupt code
289 * Complete the register saves and invoke the handler which is passed in $v0
290 */
291NESTED(except_vec_vi_handler, 0, sp)
292	SAVE_TEMP
293	SAVE_STATIC
294	CLI
295#ifdef CONFIG_TRACE_IRQFLAGS
296	move	s0, v0
297	TRACE_IRQS_OFF
298	move	v0, s0
299#endif
300
301	LONG_L	s0, TI_REGS($28)
302	LONG_S	sp, TI_REGS($28)
303
304	/*
305	 * SAVE_ALL ensures we are using a valid kernel stack for the thread.
306	 * Check if we are already using the IRQ stack.
307	 */
308	move	s1, sp # Preserve the sp
309
310	/* Get IRQ stack for this CPU */
311	ASM_CPUID_MFC0	k0, ASM_SMP_CPUID_REG
312#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
313	lui	k1, %hi(irq_stack)
314#else
315	lui	k1, %highest(irq_stack)
316	daddiu	k1, %higher(irq_stack)
317	dsll	k1, 16
318	daddiu	k1, %hi(irq_stack)
319	dsll	k1, 16
320#endif
321	LONG_SRL	k0, SMP_CPUID_PTRSHIFT
322	LONG_ADDU	k1, k0
323	LONG_L	t0, %lo(irq_stack)(k1)
324
325	# Check if already on IRQ stack
326	PTR_LI	t1, ~(_THREAD_SIZE-1)
327	and	t1, t1, sp
328	beq	t0, t1, 2f
329
330	/* Switch to IRQ stack */
331	li	t1, _IRQ_STACK_START
332	PTR_ADD sp, t0, t1
333
334	/* Save task's sp on IRQ stack so that unwinding can follow it */
335	LONG_S	s1, 0(sp)
3362:
337	jalr	v0
338
339	/* Restore sp */
340	move	sp, s1
341
342	j	ret_from_irq
343	END(except_vec_vi_handler)
344
345/*
346 * EJTAG debug exception handler.
347 */
348NESTED(ejtag_debug_handler, PT_SIZE, sp)
349	.set	push
350	.set	noat
351	MTC0	k0, CP0_DESAVE
352	mfc0	k0, CP0_DEBUG
353
354	sll	k0, k0, 30	# Check for SDBBP.
355	bgez	k0, ejtag_return
356
357	PTR_LA	k0, ejtag_debug_buffer
358	LONG_S	k1, 0(k0)
359	SAVE_ALL
360	move	a0, sp
361	jal	ejtag_exception_handler
362	RESTORE_ALL
363	PTR_LA	k0, ejtag_debug_buffer
364	LONG_L	k1, 0(k0)
365
366ejtag_return:
367	MFC0	k0, CP0_DESAVE
368	.set	mips32
369	deret
370	.set	pop
371	END(ejtag_debug_handler)
372
373/*
374 * This buffer is reserved for the use of the EJTAG debug
375 * handler.
376 */
377	.data
378EXPORT(ejtag_debug_buffer)
379	.fill	LONGSIZE
380	.previous
381
382	__INIT
383
384/*
385 * NMI debug exception handler for MIPS reference boards.
386 * The NMI debug exception entry point is 0xbfc00000, which
387 * normally is in the boot PROM, so the boot PROM must do a
388 * unconditional jump to this vector.
389 */
390NESTED(except_vec_nmi, 0, sp)
391	j	nmi_handler
392#ifdef CONFIG_CPU_MICROMIPS
393	 nop
394#endif
395	END(except_vec_nmi)
396
397	__FINIT
398
399NESTED(nmi_handler, PT_SIZE, sp)
400	.cfi_signal_frame
401	.set	push
402	.set	noat
403	/*
404	 * Clear ERL - restore segment mapping
405	 * Clear BEV - required for page fault exception handler to work
406	 */
407	mfc0	k0, CP0_STATUS
408	ori	k0, k0, ST0_EXL
409	li	k1, ~(ST0_BEV | ST0_ERL)
410	and	k0, k0, k1
411	mtc0	k0, CP0_STATUS
412	_ehb
413	SAVE_ALL
414	move	a0, sp
415	jal	nmi_exception_handler
416	/* nmi_exception_handler never returns */
417	.set	pop
418	END(nmi_handler)
419
420	.macro	__build_clear_none
421	.endm
422
423	.macro	__build_clear_sti
424	TRACE_IRQS_ON
425	STI
426	.endm
427
428	.macro	__build_clear_cli
429	CLI
430	TRACE_IRQS_OFF
431	.endm
432
433	.macro	__build_clear_fpe
434	.set	push
435	/* gas fails to assemble cfc1 for some archs (octeon).*/ \
436	.set	mips1
437	SET_HARDFLOAT
438	cfc1	a1, fcr31
439	.set	pop
440	CLI
441	TRACE_IRQS_OFF
442	.endm
443
444	.macro	__build_clear_msa_fpe
445	_cfcmsa	a1, MSA_CSR
446	CLI
447	TRACE_IRQS_OFF
448	.endm
449
450	.macro	__build_clear_ade
451	MFC0	t0, CP0_BADVADDR
452	PTR_S	t0, PT_BVADDR(sp)
453	KMODE
454	.endm
455
456	.macro	__BUILD_silent exception
457	.endm
458
459	/* Gas tries to parse the PRINT argument as a string containing
460	   string escapes and emits bogus warnings if it believes to
461	   recognize an unknown escape code.  So make the arguments
462	   start with an n and gas will believe \n is ok ...  */
463	.macro	__BUILD_verbose nexception
464	LONG_L	a1, PT_EPC(sp)
465#ifdef CONFIG_32BIT
466	PRINT("Got \nexception at %08lx\012")
467#endif
468#ifdef CONFIG_64BIT
469	PRINT("Got \nexception at %016lx\012")
470#endif
471	.endm
472
473	.macro	__BUILD_count exception
474	LONG_L	t0,exception_count_\exception
475	LONG_ADDIU	t0, 1
476	LONG_S	t0,exception_count_\exception
477	.comm	exception_count\exception, 8, 8
478	.endm
479
480	.macro	__BUILD_HANDLER exception handler clear verbose ext
481	.align	5
482	NESTED(handle_\exception, PT_SIZE, sp)
483	.cfi_signal_frame
484	.set	noat
485	SAVE_ALL
486	FEXPORT(handle_\exception\ext)
487	__build_clear_\clear
488	.set	at
489	__BUILD_\verbose \exception
490	move	a0, sp
491	jal	do_\handler
492	j	ret_from_exception
493	END(handle_\exception)
494	.endm
495
496	.macro	BUILD_HANDLER exception handler clear verbose
497	__BUILD_HANDLER \exception \handler \clear \verbose _int
498	.endm
499
500	BUILD_HANDLER adel ade ade silent		/* #4  */
501	BUILD_HANDLER ades ade ade silent		/* #5  */
502	BUILD_HANDLER ibe be cli silent			/* #6  */
503	BUILD_HANDLER dbe be cli silent			/* #7  */
504	BUILD_HANDLER bp bp sti silent			/* #9  */
505	BUILD_HANDLER ri ri sti silent			/* #10 */
506	BUILD_HANDLER cpu cpu sti silent		/* #11 */
507	BUILD_HANDLER ov ov sti silent			/* #12 */
508	BUILD_HANDLER tr tr sti silent			/* #13 */
509	BUILD_HANDLER msa_fpe msa_fpe msa_fpe silent	/* #14 */
510	BUILD_HANDLER fpe fpe fpe silent		/* #15 */
511	BUILD_HANDLER ftlb ftlb none silent		/* #16 */
512	BUILD_HANDLER msa msa sti silent		/* #21 */
513	BUILD_HANDLER mdmx mdmx sti silent		/* #22 */
514#ifdef	CONFIG_HARDWARE_WATCHPOINTS
515	/*
516	 * For watch, interrupts will be enabled after the watch
517	 * registers are read.
518	 */
519	BUILD_HANDLER watch watch cli silent		/* #23 */
520#else
521	BUILD_HANDLER watch watch sti verbose		/* #23 */
522#endif
523	BUILD_HANDLER mcheck mcheck cli verbose		/* #24 */
524	BUILD_HANDLER mt mt sti silent			/* #25 */
525	BUILD_HANDLER dsp dsp sti silent		/* #26 */
526	BUILD_HANDLER reserved reserved sti verbose	/* others */
527
528	.align	5
529	LEAF(handle_ri_rdhwr_tlbp)
530	.set	push
531	.set	noat
532	.set	noreorder
533	/* check if TLB contains a entry for EPC */
534	MFC0	k1, CP0_ENTRYHI
535	andi	k1, MIPS_ENTRYHI_ASID | MIPS_ENTRYHI_ASIDX
536	MFC0	k0, CP0_EPC
537	PTR_SRL	k0, _PAGE_SHIFT + 1
538	PTR_SLL	k0, _PAGE_SHIFT + 1
539	or	k1, k0
540	MTC0	k1, CP0_ENTRYHI
541	mtc0_tlbw_hazard
542	tlbp
543	tlb_probe_hazard
544	mfc0	k1, CP0_INDEX
545	.set	pop
546	bltz	k1, handle_ri	/* slow path */
547	/* fall thru */
548	END(handle_ri_rdhwr_tlbp)
549
550	LEAF(handle_ri_rdhwr)
551	.set	push
552	.set	noat
553	.set	noreorder
554	/* MIPS32:    0x7c03e83b: rdhwr v1,$29 */
555	/* microMIPS: 0x007d6b3c: rdhwr v1,$29 */
556	MFC0	k1, CP0_EPC
557#if defined(CONFIG_CPU_MICROMIPS) || defined(CONFIG_CPU_MIPS32_R2) || defined(CONFIG_CPU_MIPS64_R2)
558	and	k0, k1, 1
559	beqz	k0, 1f
560	 xor	k1, k0
561	lhu	k0, (k1)
562	lhu	k1, 2(k1)
563	ins	k1, k0, 16, 16
564	lui	k0, 0x007d
565	b	docheck
566	 ori	k0, 0x6b3c
5671:
568	lui	k0, 0x7c03
569	lw	k1, (k1)
570	ori	k0, 0xe83b
571#else
572	andi	k0, k1, 1
573	bnez	k0, handle_ri
574	 lui	k0, 0x7c03
575	lw	k1, (k1)
576	ori	k0, 0xe83b
577#endif
578	.set	reorder
579docheck:
580	bne	k0, k1, handle_ri	/* if not ours */
581
582isrdhwr:
583	/* The insn is rdhwr.  No need to check CAUSE.BD here. */
584	get_saved_sp	/* k1 := current_thread_info */
585	.set	noreorder
586	MFC0	k0, CP0_EPC
587#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
588	ori	k1, _THREAD_MASK
589	xori	k1, _THREAD_MASK
590	LONG_L	v1, TI_TP_VALUE(k1)
591	LONG_ADDIU	k0, 4
592	jr	k0
593	 rfe
594#else
595#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
596	LONG_ADDIU	k0, 4		/* stall on $k0 */
597#else
598	.set	at=v1
599	LONG_ADDIU	k0, 4
600	.set	noat
601#endif
602	MTC0	k0, CP0_EPC
603	/* I hope three instructions between MTC0 and ERET are enough... */
604	ori	k1, _THREAD_MASK
605	xori	k1, _THREAD_MASK
606	LONG_L	v1, TI_TP_VALUE(k1)
607	.set	arch=r4000
608	eret
609	.set	mips0
610#endif
611	.set	pop
612	END(handle_ri_rdhwr)
613
614#ifdef CONFIG_64BIT
615/* A temporary overflow handler used by check_daddi(). */
616
617	__INIT
618
619	BUILD_HANDLER  daddi_ov daddi_ov none silent	/* #12 */
620#endif
621