xref: /openbmc/linux/arch/mips/kernel/genex.S (revision 2a598d0b) 
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/sync.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	mfc0	k1, CP0_CAUSE
36	andi	k1, k1, 0x7c
37#ifdef CONFIG_64BIT
38	dsll	k1, k1, 1
39#endif
40	PTR_L	k0, exception_handlers(k1)
41	jr	k0
42	.set	pop
43	END(except_vec3_generic)
44
45/*
46 * General exception handler for CPUs with virtual coherency exception.
47 *
48 * Be careful when changing this, it has to be at most 256 (as a special
49 * exception) bytes to fit into space reserved for the exception handler.
50 */
51NESTED(except_vec3_r4000, 0, sp)
52	.set	push
53	.set	arch=r4000
54	.set	noat
55	mfc0	k1, CP0_CAUSE
56	li	k0, 31<<2
57	andi	k1, k1, 0x7c
58	.set	push
59	.set	noreorder
60	.set	nomacro
61	beq	k1, k0, handle_vced
62	 li	k0, 14<<2
63	beq	k1, k0, handle_vcei
64#ifdef CONFIG_64BIT
65	 dsll	k1, k1, 1
66#endif
67	.set	pop
68	PTR_L	k0, exception_handlers(k1)
69	jr	k0
70
71	/*
72	 * Big shit, we now may have two dirty primary cache lines for the same
73	 * physical address.  We can safely invalidate the line pointed to by
74	 * c0_badvaddr because after return from this exception handler the
75	 * load / store will be re-executed.
76	 */
77handle_vced:
78	MFC0	k0, CP0_BADVADDR
79	li	k1, -4					# Is this ...
80	and	k0, k1					# ... really needed?
81	mtc0	zero, CP0_TAGLO
82	cache	Index_Store_Tag_D, (k0)
83	cache	Hit_Writeback_Inv_SD, (k0)
84#ifdef CONFIG_PROC_FS
85	PTR_LA	k0, vced_count
86	lw	k1, (k0)
87	addiu	k1, 1
88	sw	k1, (k0)
89#endif
90	eret
91
92handle_vcei:
93	MFC0	k0, CP0_BADVADDR
94	cache	Hit_Writeback_Inv_SD, (k0)		# also cleans pi
95#ifdef CONFIG_PROC_FS
96	PTR_LA	k0, vcei_count
97	lw	k1, (k0)
98	addiu	k1, 1
99	sw	k1, (k0)
100#endif
101	eret
102	.set	pop
103	END(except_vec3_r4000)
104
105	__FINIT
106
107	.align	5	/* 32 byte rollback region */
108LEAF(__r4k_wait)
109	.set	push
110	.set	noreorder
111	/* start of rollback region */
112	LONG_L	t0, TI_FLAGS($28)
113	nop
114	andi	t0, _TIF_NEED_RESCHED
115	bnez	t0, 1f
116	 nop
117	nop
118	nop
119#ifdef CONFIG_CPU_MICROMIPS
120	nop
121	nop
122	nop
123	nop
124#endif
125	.set	MIPS_ISA_ARCH_LEVEL_RAW
126	wait
127	/* end of rollback region (the region size must be power of two) */
1281:
129	jr	ra
130	 nop
131	.set	pop
132	END(__r4k_wait)
133
134	.macro	BUILD_ROLLBACK_PROLOGUE handler
135	FEXPORT(rollback_\handler)
136	.set	push
137	.set	noat
138	MFC0	k0, CP0_EPC
139	PTR_LA	k1, __r4k_wait
140	ori	k0, 0x1f	/* 32 byte rollback region */
141	xori	k0, 0x1f
142	bne	k0, k1, \handler
143	MTC0	k0, CP0_EPC
144	.set pop
145	.endm
146
147	.align	5
148BUILD_ROLLBACK_PROLOGUE handle_int
149NESTED(handle_int, PT_SIZE, sp)
150	.cfi_signal_frame
151#ifdef CONFIG_TRACE_IRQFLAGS
152	/*
153	 * Check to see if the interrupted code has just disabled
154	 * interrupts and ignore this interrupt for now if so.
155	 *
156	 * local_irq_disable() disables interrupts and then calls
157	 * trace_hardirqs_off() to track the state. If an interrupt is taken
158	 * after interrupts are disabled but before the state is updated
159	 * it will appear to restore_all that it is incorrectly returning with
160	 * interrupts disabled
161	 */
162	.set	push
163	.set	noat
164	mfc0	k0, CP0_STATUS
165#if defined(CONFIG_CPU_R3000)
166	and	k0, ST0_IEP
167	bnez	k0, 1f
168
169	mfc0	k0, CP0_EPC
170	.set	noreorder
171	j	k0
172	 rfe
173#else
174	and	k0, ST0_IE
175	bnez	k0, 1f
176
177	eret
178#endif
1791:
180	.set pop
181#endif
182	SAVE_ALL docfi=1
183	CLI
184	TRACE_IRQS_OFF
185
186	LONG_L	s0, TI_REGS($28)
187	LONG_S	sp, TI_REGS($28)
188
189	/*
190	 * SAVE_ALL ensures we are using a valid kernel stack for the thread.
191	 * Check if we are already using the IRQ stack.
192	 */
193	move	s1, sp # Preserve the sp
194
195	/* Get IRQ stack for this CPU */
196	ASM_CPUID_MFC0	k0, ASM_SMP_CPUID_REG
197#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
198	lui	k1, %hi(irq_stack)
199#else
200	lui	k1, %highest(irq_stack)
201	daddiu	k1, %higher(irq_stack)
202	dsll	k1, 16
203	daddiu	k1, %hi(irq_stack)
204	dsll	k1, 16
205#endif
206	LONG_SRL	k0, SMP_CPUID_PTRSHIFT
207	LONG_ADDU	k1, k0
208	LONG_L	t0, %lo(irq_stack)(k1)
209
210	# Check if already on IRQ stack
211	PTR_LI	t1, ~(_THREAD_SIZE-1)
212	and	t1, t1, sp
213	beq	t0, t1, 2f
214
215	/* Switch to IRQ stack */
216	li	t1, _IRQ_STACK_START
217	PTR_ADD sp, t0, t1
218
219	/* Save task's sp on IRQ stack so that unwinding can follow it */
220	LONG_S	s1, 0(sp)
2212:
222	jal	plat_irq_dispatch
223
224	/* Restore sp */
225	move	sp, s1
226
227	j	ret_from_irq
228#ifdef CONFIG_CPU_MICROMIPS
229	nop
230#endif
231	END(handle_int)
232
233	__INIT
234
235/*
236 * Special interrupt vector for MIPS64 ISA & embedded MIPS processors.
237 * This is a dedicated interrupt exception vector which reduces the
238 * interrupt processing overhead.  The jump instruction will be replaced
239 * at the initialization time.
240 *
241 * Be careful when changing this, it has to be at most 128 bytes
242 * to fit into space reserved for the exception handler.
243 */
244NESTED(except_vec4, 0, sp)
2451:	j	1b			/* Dummy, will be replaced */
246	END(except_vec4)
247
248/*
249 * EJTAG debug exception handler.
250 * The EJTAG debug exception entry point is 0xbfc00480, which
251 * normally is in the boot PROM, so the boot PROM must do an
252 * unconditional jump to this vector.
253 */
254NESTED(except_vec_ejtag_debug, 0, sp)
255	j	ejtag_debug_handler
256#ifdef CONFIG_CPU_MICROMIPS
257	 nop
258#endif
259	END(except_vec_ejtag_debug)
260
261	__FINIT
262
263/*
264 * Vectored interrupt handler.
265 * This prototype is copied to ebase + n*IntCtl.VS and patched
266 * to invoke the handler
267 */
268BUILD_ROLLBACK_PROLOGUE except_vec_vi
269NESTED(except_vec_vi, 0, sp)
270	SAVE_SOME docfi=1
271	SAVE_AT docfi=1
272	.set	push
273	.set	noreorder
274	PTR_LA	v1, except_vec_vi_handler
275FEXPORT(except_vec_vi_lui)
276	lui	v0, 0		/* Patched */
277	jr	v1
278FEXPORT(except_vec_vi_ori)
279	 ori	v0, 0		/* Patched */
280	.set	pop
281	END(except_vec_vi)
282EXPORT(except_vec_vi_end)
283
284/*
285 * Common Vectored Interrupt code
286 * Complete the register saves and invoke the handler which is passed in $v0
287 */
288NESTED(except_vec_vi_handler, 0, sp)
289	SAVE_TEMP
290	SAVE_STATIC
291	CLI
292#ifdef CONFIG_TRACE_IRQFLAGS
293	move	s0, v0
294	TRACE_IRQS_OFF
295	move	v0, s0
296#endif
297
298	LONG_L	s0, TI_REGS($28)
299	LONG_S	sp, TI_REGS($28)
300
301	/*
302	 * SAVE_ALL ensures we are using a valid kernel stack for the thread.
303	 * Check if we are already using the IRQ stack.
304	 */
305	move	s1, sp # Preserve the sp
306
307	/* Get IRQ stack for this CPU */
308	ASM_CPUID_MFC0	k0, ASM_SMP_CPUID_REG
309#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
310	lui	k1, %hi(irq_stack)
311#else
312	lui	k1, %highest(irq_stack)
313	daddiu	k1, %higher(irq_stack)
314	dsll	k1, 16
315	daddiu	k1, %hi(irq_stack)
316	dsll	k1, 16
317#endif
318	LONG_SRL	k0, SMP_CPUID_PTRSHIFT
319	LONG_ADDU	k1, k0
320	LONG_L	t0, %lo(irq_stack)(k1)
321
322	# Check if already on IRQ stack
323	PTR_LI	t1, ~(_THREAD_SIZE-1)
324	and	t1, t1, sp
325	beq	t0, t1, 2f
326
327	/* Switch to IRQ stack */
328	li	t1, _IRQ_STACK_START
329	PTR_ADD sp, t0, t1
330
331	/* Save task's sp on IRQ stack so that unwinding can follow it */
332	LONG_S	s1, 0(sp)
3332:
334	jalr	v0
335
336	/* Restore sp */
337	move	sp, s1
338
339	j	ret_from_irq
340	END(except_vec_vi_handler)
341
342/*
343 * EJTAG debug exception handler.
344 */
345NESTED(ejtag_debug_handler, PT_SIZE, sp)
346	.set	push
347	.set	noat
348	MTC0	k0, CP0_DESAVE
349	mfc0	k0, CP0_DEBUG
350
351	andi	k0, k0, MIPS_DEBUG_DBP	# Check for SDBBP.
352	beqz	k0, ejtag_return
353
354#ifdef CONFIG_SMP
3551:	PTR_LA	k0, ejtag_debug_buffer_spinlock
356	__SYNC(full, loongson3_war)
3572:	ll	k0, 0(k0)
358	bnez	k0, 2b
359	PTR_LA	k0, ejtag_debug_buffer_spinlock
360	sc	k0, 0(k0)
361	beqz	k0, 1b
362# ifdef CONFIG_WEAK_REORDERING_BEYOND_LLSC
363	sync
364# endif
365
366	PTR_LA	k0, ejtag_debug_buffer
367	LONG_S	k1, 0(k0)
368
369	ASM_CPUID_MFC0 k1, ASM_SMP_CPUID_REG
370	PTR_SRL	k1, SMP_CPUID_PTRSHIFT
371	PTR_SLL	k1, LONGLOG
372	PTR_LA	k0, ejtag_debug_buffer_per_cpu
373	PTR_ADDU k0, k1
374
375	PTR_LA	k1, ejtag_debug_buffer
376	LONG_L	k1, 0(k1)
377	LONG_S	k1, 0(k0)
378
379	PTR_LA	k0, ejtag_debug_buffer_spinlock
380	sw	zero, 0(k0)
381#else
382	PTR_LA	k0, ejtag_debug_buffer
383	LONG_S	k1, 0(k0)
384#endif
385
386	SAVE_ALL
387	move	a0, sp
388	jal	ejtag_exception_handler
389	RESTORE_ALL
390
391#ifdef CONFIG_SMP
392	ASM_CPUID_MFC0 k1, ASM_SMP_CPUID_REG
393	PTR_SRL	k1, SMP_CPUID_PTRSHIFT
394	PTR_SLL	k1, LONGLOG
395	PTR_LA	k0, ejtag_debug_buffer_per_cpu
396	PTR_ADDU k0, k1
397	LONG_L	k1, 0(k0)
398#else
399	PTR_LA	k0, ejtag_debug_buffer
400	LONG_L	k1, 0(k0)
401#endif
402
403ejtag_return:
404	back_to_back_c0_hazard
405	MFC0	k0, CP0_DESAVE
406	.set	mips32
407	deret
408	.set	pop
409	END(ejtag_debug_handler)
410
411/*
412 * This buffer is reserved for the use of the EJTAG debug
413 * handler.
414 */
415	.data
416EXPORT(ejtag_debug_buffer)
417	.fill	LONGSIZE
418#ifdef CONFIG_SMP
419EXPORT(ejtag_debug_buffer_spinlock)
420	.fill	LONGSIZE
421EXPORT(ejtag_debug_buffer_per_cpu)
422	.fill	LONGSIZE * NR_CPUS
423#endif
424	.previous
425
426	__INIT
427
428/*
429 * NMI debug exception handler for MIPS reference boards.
430 * The NMI debug exception entry point is 0xbfc00000, which
431 * normally is in the boot PROM, so the boot PROM must do a
432 * unconditional jump to this vector.
433 */
434NESTED(except_vec_nmi, 0, sp)
435	j	nmi_handler
436#ifdef CONFIG_CPU_MICROMIPS
437	 nop
438#endif
439	END(except_vec_nmi)
440
441	__FINIT
442
443NESTED(nmi_handler, PT_SIZE, sp)
444	.cfi_signal_frame
445	.set	push
446	.set	noat
447	/*
448	 * Clear ERL - restore segment mapping
449	 * Clear BEV - required for page fault exception handler to work
450	 */
451	mfc0	k0, CP0_STATUS
452	ori	k0, k0, ST0_EXL
453	li	k1, ~(ST0_BEV | ST0_ERL)
454	and	k0, k0, k1
455	mtc0	k0, CP0_STATUS
456	_ehb
457	SAVE_ALL
458	move	a0, sp
459	jal	nmi_exception_handler
460	/* nmi_exception_handler never returns */
461	.set	pop
462	END(nmi_handler)
463
464	.macro	__build_clear_none
465	.endm
466
467	.macro	__build_clear_sti
468	TRACE_IRQS_ON
469	STI
470	.endm
471
472	.macro	__build_clear_cli
473	CLI
474	TRACE_IRQS_OFF
475	.endm
476
477	.macro	__build_clear_fpe
478	CLI
479	TRACE_IRQS_OFF
480	.set	push
481	/* gas fails to assemble cfc1 for some archs (octeon).*/ \
482	.set	mips1
483	.set	hardfloat
484	cfc1	a1, fcr31
485	.set	pop
486	.endm
487
488	.macro	__build_clear_msa_fpe
489	CLI
490	TRACE_IRQS_OFF
491	_cfcmsa	a1, MSA_CSR
492	.endm
493
494	.macro	__build_clear_ade
495	MFC0	t0, CP0_BADVADDR
496	PTR_S	t0, PT_BVADDR(sp)
497	KMODE
498	.endm
499
500	.macro __build_clear_gsexc
501	.set	push
502	/*
503	 * We need to specify a selector to access the CP0.Diag1 (GSCause)
504	 * register. All GSExc-equipped processors have MIPS32.
505	 */
506	.set	mips32
507	mfc0	a1, CP0_DIAGNOSTIC1
508	.set	pop
509	TRACE_IRQS_ON
510	STI
511	.endm
512
513	.macro	__BUILD_silent exception
514	.endm
515
516	/* Gas tries to parse the ASM_PRINT argument as a string containing
517	   string escapes and emits bogus warnings if it believes to
518	   recognize an unknown escape code.  So make the arguments
519	   start with an n and gas will believe \n is ok ...  */
520	.macro	__BUILD_verbose nexception
521	LONG_L	a1, PT_EPC(sp)
522#ifdef CONFIG_32BIT
523	ASM_PRINT("Got \nexception at %08lx\012")
524#endif
525#ifdef CONFIG_64BIT
526	ASM_PRINT("Got \nexception at %016lx\012")
527#endif
528	.endm
529
530	.macro	__BUILD_count exception
531	LONG_L	t0,exception_count_\exception
532	LONG_ADDIU	t0, 1
533	LONG_S	t0,exception_count_\exception
534	.comm	exception_count\exception, 8, 8
535	.endm
536
537	.macro	__BUILD_HANDLER exception handler clear verbose ext
538	.align	5
539	NESTED(handle_\exception, PT_SIZE, sp)
540	.cfi_signal_frame
541	.set	noat
542	SAVE_ALL
543	FEXPORT(handle_\exception\ext)
544	__build_clear_\clear
545	.set	at
546	__BUILD_\verbose \exception
547	move	a0, sp
548	jal	do_\handler
549	j	ret_from_exception
550	END(handle_\exception)
551	.endm
552
553	.macro	BUILD_HANDLER exception handler clear verbose
554	__BUILD_HANDLER \exception \handler \clear \verbose _int
555	.endm
556
557	BUILD_HANDLER adel ade ade silent		/* #4  */
558	BUILD_HANDLER ades ade ade silent		/* #5  */
559	BUILD_HANDLER ibe be cli silent			/* #6  */
560	BUILD_HANDLER dbe be cli silent			/* #7  */
561	BUILD_HANDLER bp bp sti silent			/* #9  */
562	BUILD_HANDLER ri ri sti silent			/* #10 */
563	BUILD_HANDLER cpu cpu sti silent		/* #11 */
564	BUILD_HANDLER ov ov sti silent			/* #12 */
565	BUILD_HANDLER tr tr sti silent			/* #13 */
566	BUILD_HANDLER msa_fpe msa_fpe msa_fpe silent	/* #14 */
567#ifdef CONFIG_MIPS_FP_SUPPORT
568	BUILD_HANDLER fpe fpe fpe silent		/* #15 */
569#endif
570	BUILD_HANDLER ftlb ftlb none silent		/* #16 */
571	BUILD_HANDLER gsexc gsexc gsexc silent		/* #16 */
572	BUILD_HANDLER msa msa sti silent		/* #21 */
573	BUILD_HANDLER mdmx mdmx sti silent		/* #22 */
574#ifdef	CONFIG_HARDWARE_WATCHPOINTS
575	/*
576	 * For watch, interrupts will be enabled after the watch
577	 * registers are read.
578	 */
579	BUILD_HANDLER watch watch cli silent		/* #23 */
580#else
581	BUILD_HANDLER watch watch sti verbose		/* #23 */
582#endif
583	BUILD_HANDLER mcheck mcheck cli verbose		/* #24 */
584	BUILD_HANDLER mt mt sti silent			/* #25 */
585	BUILD_HANDLER dsp dsp sti silent		/* #26 */
586	BUILD_HANDLER reserved reserved sti verbose	/* others */
587
588	.align	5
589	LEAF(handle_ri_rdhwr_tlbp)
590	.set	push
591	.set	noat
592	.set	noreorder
593	/* check if TLB contains a entry for EPC */
594	MFC0	k1, CP0_ENTRYHI
595	andi	k1, MIPS_ENTRYHI_ASID | MIPS_ENTRYHI_ASIDX
596	MFC0	k0, CP0_EPC
597	PTR_SRL	k0, _PAGE_SHIFT + 1
598	PTR_SLL	k0, _PAGE_SHIFT + 1
599	or	k1, k0
600	MTC0	k1, CP0_ENTRYHI
601	mtc0_tlbw_hazard
602	tlbp
603	tlb_probe_hazard
604	mfc0	k1, CP0_INDEX
605	.set	pop
606	bltz	k1, handle_ri	/* slow path */
607	/* fall thru */
608	END(handle_ri_rdhwr_tlbp)
609
610	LEAF(handle_ri_rdhwr)
611	.set	push
612	.set	noat
613	.set	noreorder
614	/* MIPS32:    0x7c03e83b: rdhwr v1,$29 */
615	/* microMIPS: 0x007d6b3c: rdhwr v1,$29 */
616	MFC0	k1, CP0_EPC
617#if defined(CONFIG_CPU_MICROMIPS) || defined(CONFIG_CPU_MIPS32_R2) || defined(CONFIG_CPU_MIPS64_R2)
618	and	k0, k1, 1
619	beqz	k0, 1f
620	 xor	k1, k0
621	lhu	k0, (k1)
622	lhu	k1, 2(k1)
623	ins	k1, k0, 16, 16
624	lui	k0, 0x007d
625	b	docheck
626	 ori	k0, 0x6b3c
6271:
628	lui	k0, 0x7c03
629	lw	k1, (k1)
630	ori	k0, 0xe83b
631#else
632	andi	k0, k1, 1
633	bnez	k0, handle_ri
634	 lui	k0, 0x7c03
635	lw	k1, (k1)
636	ori	k0, 0xe83b
637#endif
638	.set	reorder
639docheck:
640	bne	k0, k1, handle_ri	/* if not ours */
641
642isrdhwr:
643	/* The insn is rdhwr.  No need to check CAUSE.BD here. */
644	get_saved_sp	/* k1 := current_thread_info */
645	.set	noreorder
646	MFC0	k0, CP0_EPC
647#if defined(CONFIG_CPU_R3000)
648	ori	k1, _THREAD_MASK
649	xori	k1, _THREAD_MASK
650	LONG_L	v1, TI_TP_VALUE(k1)
651	LONG_ADDIU	k0, 4
652	jr	k0
653	 rfe
654#else
655#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
656	LONG_ADDIU	k0, 4		/* stall on $k0 */
657#else
658	.set	at=v1
659	LONG_ADDIU	k0, 4
660	.set	noat
661#endif
662	MTC0	k0, CP0_EPC
663	/* I hope three instructions between MTC0 and ERET are enough... */
664	ori	k1, _THREAD_MASK
665	xori	k1, _THREAD_MASK
666	LONG_L	v1, TI_TP_VALUE(k1)
667	.set	push
668	.set	arch=r4000
669	eret
670	.set	pop
671#endif
672	.set	pop
673	END(handle_ri_rdhwr)
674
675#ifdef CONFIG_CPU_R4X00_BUGS64
676/* A temporary overflow handler used by check_daddi(). */
677
678	__INIT
679
680	BUILD_HANDLER  daddi_ov daddi_ov none silent	/* #12 */
681#endif
682