xref: /openbmc/linux/arch/mips/kernel/genex.S (revision 20e2fc42) 
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	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) || defined(CONFIG_CPU_TX39XX)
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	sll	k0, k0, 30	# Check for SDBBP.
352	bgez	k0, ejtag_return
353
354#ifdef CONFIG_SMP
3551:	PTR_LA	k0, ejtag_debug_buffer_spinlock
356	ll	k0, 0(k0)
357	bnez	k0, 1b
358	PTR_LA	k0, ejtag_debug_buffer_spinlock
359	sc	k0, 0(k0)
360	beqz	k0, 1b
361# ifdef CONFIG_WEAK_REORDERING_BEYOND_LLSC
362	sync
363# endif
364
365	PTR_LA	k0, ejtag_debug_buffer
366	LONG_S	k1, 0(k0)
367
368	ASM_CPUID_MFC0 k1, ASM_SMP_CPUID_REG
369	PTR_SRL	k1, SMP_CPUID_PTRSHIFT
370	PTR_SLL	k1, LONGLOG
371	PTR_LA	k0, ejtag_debug_buffer_per_cpu
372	PTR_ADDU k0, k1
373
374	PTR_LA	k1, ejtag_debug_buffer
375	LONG_L	k1, 0(k1)
376	LONG_S	k1, 0(k0)
377
378	PTR_LA	k0, ejtag_debug_buffer_spinlock
379	sw	zero, 0(k0)
380#else
381	PTR_LA	k0, ejtag_debug_buffer
382	LONG_S	k1, 0(k0)
383#endif
384
385	SAVE_ALL
386	move	a0, sp
387	jal	ejtag_exception_handler
388	RESTORE_ALL
389
390#ifdef CONFIG_SMP
391	ASM_CPUID_MFC0 k1, ASM_SMP_CPUID_REG
392	PTR_SRL	k1, SMP_CPUID_PTRSHIFT
393	PTR_SLL	k1, LONGLOG
394	PTR_LA	k0, ejtag_debug_buffer_per_cpu
395	PTR_ADDU k0, k1
396	LONG_L	k1, 0(k0)
397#else
398	PTR_LA	k0, ejtag_debug_buffer
399	LONG_L	k1, 0(k0)
400#endif
401
402ejtag_return:
403	back_to_back_c0_hazard
404	MFC0	k0, CP0_DESAVE
405	.set	mips32
406	deret
407	.set	pop
408	END(ejtag_debug_handler)
409
410/*
411 * This buffer is reserved for the use of the EJTAG debug
412 * handler.
413 */
414	.data
415EXPORT(ejtag_debug_buffer)
416	.fill	LONGSIZE
417#ifdef CONFIG_SMP
418EXPORT(ejtag_debug_buffer_spinlock)
419	.fill	LONGSIZE
420EXPORT(ejtag_debug_buffer_per_cpu)
421	.fill	LONGSIZE * NR_CPUS
422#endif
423	.previous
424
425	__INIT
426
427/*
428 * NMI debug exception handler for MIPS reference boards.
429 * The NMI debug exception entry point is 0xbfc00000, which
430 * normally is in the boot PROM, so the boot PROM must do a
431 * unconditional jump to this vector.
432 */
433NESTED(except_vec_nmi, 0, sp)
434	j	nmi_handler
435#ifdef CONFIG_CPU_MICROMIPS
436	 nop
437#endif
438	END(except_vec_nmi)
439
440	__FINIT
441
442NESTED(nmi_handler, PT_SIZE, sp)
443	.cfi_signal_frame
444	.set	push
445	.set	noat
446	/*
447	 * Clear ERL - restore segment mapping
448	 * Clear BEV - required for page fault exception handler to work
449	 */
450	mfc0	k0, CP0_STATUS
451	ori	k0, k0, ST0_EXL
452	li	k1, ~(ST0_BEV | ST0_ERL)
453	and	k0, k0, k1
454	mtc0	k0, CP0_STATUS
455	_ehb
456	SAVE_ALL
457	move	a0, sp
458	jal	nmi_exception_handler
459	/* nmi_exception_handler never returns */
460	.set	pop
461	END(nmi_handler)
462
463	.macro	__build_clear_none
464	.endm
465
466	.macro	__build_clear_sti
467	TRACE_IRQS_ON
468	STI
469	.endm
470
471	.macro	__build_clear_cli
472	CLI
473	TRACE_IRQS_OFF
474	.endm
475
476	.macro	__build_clear_fpe
477	.set	push
478	/* gas fails to assemble cfc1 for some archs (octeon).*/ \
479	.set	mips1
480	SET_HARDFLOAT
481	cfc1	a1, fcr31
482	.set	pop
483	CLI
484	TRACE_IRQS_OFF
485	.endm
486
487	.macro	__build_clear_msa_fpe
488	_cfcmsa	a1, MSA_CSR
489	CLI
490	TRACE_IRQS_OFF
491	.endm
492
493	.macro	__build_clear_ade
494	MFC0	t0, CP0_BADVADDR
495	PTR_S	t0, PT_BVADDR(sp)
496	KMODE
497	.endm
498
499	.macro	__BUILD_silent exception
500	.endm
501
502	/* Gas tries to parse the PRINT argument as a string containing
503	   string escapes and emits bogus warnings if it believes to
504	   recognize an unknown escape code.  So make the arguments
505	   start with an n and gas will believe \n is ok ...  */
506	.macro	__BUILD_verbose nexception
507	LONG_L	a1, PT_EPC(sp)
508#ifdef CONFIG_32BIT
509	PRINT("Got \nexception at %08lx\012")
510#endif
511#ifdef CONFIG_64BIT
512	PRINT("Got \nexception at %016lx\012")
513#endif
514	.endm
515
516	.macro	__BUILD_count exception
517	LONG_L	t0,exception_count_\exception
518	LONG_ADDIU	t0, 1
519	LONG_S	t0,exception_count_\exception
520	.comm	exception_count\exception, 8, 8
521	.endm
522
523	.macro	__BUILD_HANDLER exception handler clear verbose ext
524	.align	5
525	NESTED(handle_\exception, PT_SIZE, sp)
526	.cfi_signal_frame
527	.set	noat
528	SAVE_ALL
529	FEXPORT(handle_\exception\ext)
530	__build_clear_\clear
531	.set	at
532	__BUILD_\verbose \exception
533	move	a0, sp
534	jal	do_\handler
535	j	ret_from_exception
536	END(handle_\exception)
537	.endm
538
539	.macro	BUILD_HANDLER exception handler clear verbose
540	__BUILD_HANDLER \exception \handler \clear \verbose _int
541	.endm
542
543	BUILD_HANDLER adel ade ade silent		/* #4  */
544	BUILD_HANDLER ades ade ade silent		/* #5  */
545	BUILD_HANDLER ibe be cli silent			/* #6  */
546	BUILD_HANDLER dbe be cli silent			/* #7  */
547	BUILD_HANDLER bp bp sti silent			/* #9  */
548	BUILD_HANDLER ri ri sti silent			/* #10 */
549	BUILD_HANDLER cpu cpu sti silent		/* #11 */
550	BUILD_HANDLER ov ov sti silent			/* #12 */
551	BUILD_HANDLER tr tr sti silent			/* #13 */
552	BUILD_HANDLER msa_fpe msa_fpe msa_fpe silent	/* #14 */
553#ifdef CONFIG_MIPS_FP_SUPPORT
554	BUILD_HANDLER fpe fpe fpe silent		/* #15 */
555#endif
556	BUILD_HANDLER ftlb ftlb none silent		/* #16 */
557	BUILD_HANDLER msa msa sti silent		/* #21 */
558	BUILD_HANDLER mdmx mdmx sti silent		/* #22 */
559#ifdef	CONFIG_HARDWARE_WATCHPOINTS
560	/*
561	 * For watch, interrupts will be enabled after the watch
562	 * registers are read.
563	 */
564	BUILD_HANDLER watch watch cli silent		/* #23 */
565#else
566	BUILD_HANDLER watch watch sti verbose		/* #23 */
567#endif
568	BUILD_HANDLER mcheck mcheck cli verbose		/* #24 */
569	BUILD_HANDLER mt mt sti silent			/* #25 */
570	BUILD_HANDLER dsp dsp sti silent		/* #26 */
571	BUILD_HANDLER reserved reserved sti verbose	/* others */
572
573	.align	5
574	LEAF(handle_ri_rdhwr_tlbp)
575	.set	push
576	.set	noat
577	.set	noreorder
578	/* check if TLB contains a entry for EPC */
579	MFC0	k1, CP0_ENTRYHI
580	andi	k1, MIPS_ENTRYHI_ASID | MIPS_ENTRYHI_ASIDX
581	MFC0	k0, CP0_EPC
582	PTR_SRL	k0, _PAGE_SHIFT + 1
583	PTR_SLL	k0, _PAGE_SHIFT + 1
584	or	k1, k0
585	MTC0	k1, CP0_ENTRYHI
586	mtc0_tlbw_hazard
587	tlbp
588	tlb_probe_hazard
589	mfc0	k1, CP0_INDEX
590	.set	pop
591	bltz	k1, handle_ri	/* slow path */
592	/* fall thru */
593	END(handle_ri_rdhwr_tlbp)
594
595	LEAF(handle_ri_rdhwr)
596	.set	push
597	.set	noat
598	.set	noreorder
599	/* MIPS32:    0x7c03e83b: rdhwr v1,$29 */
600	/* microMIPS: 0x007d6b3c: rdhwr v1,$29 */
601	MFC0	k1, CP0_EPC
602#if defined(CONFIG_CPU_MICROMIPS) || defined(CONFIG_CPU_MIPS32_R2) || defined(CONFIG_CPU_MIPS64_R2)
603	and	k0, k1, 1
604	beqz	k0, 1f
605	 xor	k1, k0
606	lhu	k0, (k1)
607	lhu	k1, 2(k1)
608	ins	k1, k0, 16, 16
609	lui	k0, 0x007d
610	b	docheck
611	 ori	k0, 0x6b3c
6121:
613	lui	k0, 0x7c03
614	lw	k1, (k1)
615	ori	k0, 0xe83b
616#else
617	andi	k0, k1, 1
618	bnez	k0, handle_ri
619	 lui	k0, 0x7c03
620	lw	k1, (k1)
621	ori	k0, 0xe83b
622#endif
623	.set	reorder
624docheck:
625	bne	k0, k1, handle_ri	/* if not ours */
626
627isrdhwr:
628	/* The insn is rdhwr.  No need to check CAUSE.BD here. */
629	get_saved_sp	/* k1 := current_thread_info */
630	.set	noreorder
631	MFC0	k0, CP0_EPC
632#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
633	ori	k1, _THREAD_MASK
634	xori	k1, _THREAD_MASK
635	LONG_L	v1, TI_TP_VALUE(k1)
636	LONG_ADDIU	k0, 4
637	jr	k0
638	 rfe
639#else
640#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
641	LONG_ADDIU	k0, 4		/* stall on $k0 */
642#else
643	.set	at=v1
644	LONG_ADDIU	k0, 4
645	.set	noat
646#endif
647	MTC0	k0, CP0_EPC
648	/* I hope three instructions between MTC0 and ERET are enough... */
649	ori	k1, _THREAD_MASK
650	xori	k1, _THREAD_MASK
651	LONG_L	v1, TI_TP_VALUE(k1)
652	.set	push
653	.set	arch=r4000
654	eret
655	.set	pop
656#endif
657	.set	pop
658	END(handle_ri_rdhwr)
659
660#ifdef CONFIG_64BIT
661/* A temporary overflow handler used by check_daddi(). */
662
663	__INIT
664
665	BUILD_HANDLER  daddi_ov daddi_ov none silent	/* #12 */
666#endif
667