xref: /openbmc/linux/arch/mips/include/asm/stackframe.h (revision 4800cd83) 
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, 95, 96, 99, 2001 Ralf Baechle
7  * Copyright (C) 1994, 1995, 1996 Paul M. Antoine.
8  * Copyright (C) 1999 Silicon Graphics, Inc.
9  * Copyright (C) 2007  Maciej W. Rozycki
10  */
11 #ifndef _ASM_STACKFRAME_H
12 #define _ASM_STACKFRAME_H
13 
14 #include <linux/threads.h>
15 
16 #include <asm/asm.h>
17 #include <asm/asmmacro.h>
18 #include <asm/mipsregs.h>
19 #include <asm/asm-offsets.h>
20 
21 /*
22  * For SMTC kernel, global IE should be left set, and interrupts
23  * controlled exclusively via IXMT.
24  */
25 #ifdef CONFIG_MIPS_MT_SMTC
26 #define STATMASK 0x1e
27 #elif defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
28 #define STATMASK 0x3f
29 #else
30 #define STATMASK 0x1f
31 #endif
32 
33 #ifdef CONFIG_MIPS_MT_SMTC
34 #include <asm/mipsmtregs.h>
35 #endif /* CONFIG_MIPS_MT_SMTC */
36 
37 		.macro	SAVE_AT
38 		.set	push
39 		.set	noat
40 		LONG_S	$1, PT_R1(sp)
41 		.set	pop
42 		.endm
43 
44 		.macro	SAVE_TEMP
45 #ifdef CONFIG_CPU_HAS_SMARTMIPS
46 		mflhxu	v1
47 		LONG_S	v1, PT_LO(sp)
48 		mflhxu	v1
49 		LONG_S	v1, PT_HI(sp)
50 		mflhxu	v1
51 		LONG_S	v1, PT_ACX(sp)
52 #else
53 		mfhi	v1
54 #endif
55 #ifdef CONFIG_32BIT
56 		LONG_S	$8, PT_R8(sp)
57 		LONG_S	$9, PT_R9(sp)
58 #endif
59 		LONG_S	$10, PT_R10(sp)
60 		LONG_S	$11, PT_R11(sp)
61 		LONG_S	$12, PT_R12(sp)
62 #ifndef CONFIG_CPU_HAS_SMARTMIPS
63 		LONG_S	v1, PT_HI(sp)
64 		mflo	v1
65 #endif
66 		LONG_S	$13, PT_R13(sp)
67 		LONG_S	$14, PT_R14(sp)
68 		LONG_S	$15, PT_R15(sp)
69 		LONG_S	$24, PT_R24(sp)
70 #ifndef CONFIG_CPU_HAS_SMARTMIPS
71 		LONG_S	v1, PT_LO(sp)
72 #endif
73 		.endm
74 
75 		.macro	SAVE_STATIC
76 		LONG_S	$16, PT_R16(sp)
77 		LONG_S	$17, PT_R17(sp)
78 		LONG_S	$18, PT_R18(sp)
79 		LONG_S	$19, PT_R19(sp)
80 		LONG_S	$20, PT_R20(sp)
81 		LONG_S	$21, PT_R21(sp)
82 		LONG_S	$22, PT_R22(sp)
83 		LONG_S	$23, PT_R23(sp)
84 		LONG_S	$30, PT_R30(sp)
85 		.endm
86 
87 #ifdef CONFIG_SMP
88 #ifdef CONFIG_MIPS_MT_SMTC
89 #define PTEBASE_SHIFT	19	/* TCBIND */
90 #define CPU_ID_REG CP0_TCBIND
91 #define CPU_ID_MFC0 mfc0
92 #elif defined(CONFIG_MIPS_PGD_C0_CONTEXT)
93 #define PTEBASE_SHIFT	48	/* XCONTEXT */
94 #define CPU_ID_REG CP0_XCONTEXT
95 #define CPU_ID_MFC0 MFC0
96 #else
97 #define PTEBASE_SHIFT	23	/* CONTEXT */
98 #define CPU_ID_REG CP0_CONTEXT
99 #define CPU_ID_MFC0 MFC0
100 #endif
101 		.macro	get_saved_sp	/* SMP variation */
102 		CPU_ID_MFC0	k0, CPU_ID_REG
103 #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
104 		lui	k1, %hi(kernelsp)
105 #else
106 		lui	k1, %highest(kernelsp)
107 		daddiu	k1, %higher(kernelsp)
108 		dsll	k1, 16
109 		daddiu	k1, %hi(kernelsp)
110 		dsll	k1, 16
111 #endif
112 		LONG_SRL	k0, PTEBASE_SHIFT
113 		LONG_ADDU	k1, k0
114 		LONG_L	k1, %lo(kernelsp)(k1)
115 		.endm
116 
117 		.macro	set_saved_sp stackp temp temp2
118 		CPU_ID_MFC0	\temp, CPU_ID_REG
119 		LONG_SRL	\temp, PTEBASE_SHIFT
120 		LONG_S	\stackp, kernelsp(\temp)
121 		.endm
122 #else
123 		.macro	get_saved_sp	/* Uniprocessor variation */
124 #ifdef CONFIG_CPU_JUMP_WORKAROUNDS
125 		/*
126 		 * Clear BTB (branch target buffer), forbid RAS (return address
127 		 * stack) to workaround the Out-of-order Issue in Loongson2F
128 		 * via its diagnostic register.
129 		 */
130 		move	k0, ra
131 		jal	1f
132 		 nop
133 1:		jal	1f
134 		 nop
135 1:		jal	1f
136 		 nop
137 1:		jal	1f
138 		 nop
139 1:		move	ra, k0
140 		li	k0, 3
141 		mtc0	k0, $22
142 #endif /* CONFIG_CPU_LOONGSON2F */
143 #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
144 		lui	k1, %hi(kernelsp)
145 #else
146 		lui	k1, %highest(kernelsp)
147 		daddiu	k1, %higher(kernelsp)
148 		dsll	k1, k1, 16
149 		daddiu	k1, %hi(kernelsp)
150 		dsll	k1, k1, 16
151 #endif
152 		LONG_L	k1, %lo(kernelsp)(k1)
153 		.endm
154 
155 		.macro	set_saved_sp stackp temp temp2
156 		LONG_S	\stackp, kernelsp
157 		.endm
158 #endif
159 
160 		.macro	SAVE_SOME
161 		.set	push
162 		.set	noat
163 		.set	reorder
164 		mfc0	k0, CP0_STATUS
165 		sll	k0, 3		/* extract cu0 bit */
166 		.set	noreorder
167 		bltz	k0, 8f
168 		 move	k1, sp
169 		.set	reorder
170 		/* Called from user mode, new stack. */
171 		get_saved_sp
172 #ifndef CONFIG_CPU_DADDI_WORKAROUNDS
173 8:		move	k0, sp
174 		PTR_SUBU sp, k1, PT_SIZE
175 #else
176 		.set	at=k0
177 8:		PTR_SUBU k1, PT_SIZE
178 		.set	noat
179 		move	k0, sp
180 		move	sp, k1
181 #endif
182 		LONG_S	k0, PT_R29(sp)
183 		LONG_S	$3, PT_R3(sp)
184 		/*
185 		 * You might think that you don't need to save $0,
186 		 * but the FPU emulator and gdb remote debug stub
187 		 * need it to operate correctly
188 		 */
189 		LONG_S	$0, PT_R0(sp)
190 		mfc0	v1, CP0_STATUS
191 		LONG_S	$2, PT_R2(sp)
192 #ifdef CONFIG_MIPS_MT_SMTC
193 		/*
194 		 * Ideally, these instructions would be shuffled in
195 		 * to cover the pipeline delay.
196 		 */
197 		.set	mips32
198 		mfc0	v1, CP0_TCSTATUS
199 		.set	mips0
200 		LONG_S	v1, PT_TCSTATUS(sp)
201 #endif /* CONFIG_MIPS_MT_SMTC */
202 		LONG_S	$4, PT_R4(sp)
203 		LONG_S	$5, PT_R5(sp)
204 		LONG_S	v1, PT_STATUS(sp)
205 		mfc0	v1, CP0_CAUSE
206 		LONG_S	$6, PT_R6(sp)
207 		LONG_S	$7, PT_R7(sp)
208 		LONG_S	v1, PT_CAUSE(sp)
209 		MFC0	v1, CP0_EPC
210 #ifdef CONFIG_64BIT
211 		LONG_S	$8, PT_R8(sp)
212 		LONG_S	$9, PT_R9(sp)
213 #endif
214 		LONG_S	$25, PT_R25(sp)
215 		LONG_S	$28, PT_R28(sp)
216 		LONG_S	$31, PT_R31(sp)
217 		LONG_S	v1, PT_EPC(sp)
218 		ori	$28, sp, _THREAD_MASK
219 		xori	$28, _THREAD_MASK
220 #ifdef CONFIG_CPU_CAVIUM_OCTEON
221 		.set    mips64
222 		pref    0, 0($28)       /* Prefetch the current pointer */
223 		pref    0, PT_R31(sp)   /* Prefetch the $31(ra) */
224 		/* The Octeon multiplier state is affected by general multiply
225 		    instructions. It must be saved before and kernel code might
226 		    corrupt it */
227 		jal     octeon_mult_save
228 		LONG_L  v1, 0($28)  /* Load the current pointer */
229 			 /* Restore $31(ra) that was changed by the jal */
230 		LONG_L  ra, PT_R31(sp)
231 		pref    0, 0(v1)    /* Prefetch the current thread */
232 #endif
233 		.set	pop
234 		.endm
235 
236 		.macro	SAVE_ALL
237 		SAVE_SOME
238 		SAVE_AT
239 		SAVE_TEMP
240 		SAVE_STATIC
241 		.endm
242 
243 		.macro	RESTORE_AT
244 		.set	push
245 		.set	noat
246 		LONG_L	$1,  PT_R1(sp)
247 		.set	pop
248 		.endm
249 
250 		.macro	RESTORE_TEMP
251 #ifdef CONFIG_CPU_HAS_SMARTMIPS
252 		LONG_L	$24, PT_ACX(sp)
253 		mtlhx	$24
254 		LONG_L	$24, PT_HI(sp)
255 		mtlhx	$24
256 		LONG_L	$24, PT_LO(sp)
257 		mtlhx	$24
258 #else
259 		LONG_L	$24, PT_LO(sp)
260 		mtlo	$24
261 		LONG_L	$24, PT_HI(sp)
262 		mthi	$24
263 #endif
264 #ifdef CONFIG_32BIT
265 		LONG_L	$8, PT_R8(sp)
266 		LONG_L	$9, PT_R9(sp)
267 #endif
268 		LONG_L	$10, PT_R10(sp)
269 		LONG_L	$11, PT_R11(sp)
270 		LONG_L	$12, PT_R12(sp)
271 		LONG_L	$13, PT_R13(sp)
272 		LONG_L	$14, PT_R14(sp)
273 		LONG_L	$15, PT_R15(sp)
274 		LONG_L	$24, PT_R24(sp)
275 		.endm
276 
277 		.macro	RESTORE_STATIC
278 		LONG_L	$16, PT_R16(sp)
279 		LONG_L	$17, PT_R17(sp)
280 		LONG_L	$18, PT_R18(sp)
281 		LONG_L	$19, PT_R19(sp)
282 		LONG_L	$20, PT_R20(sp)
283 		LONG_L	$21, PT_R21(sp)
284 		LONG_L	$22, PT_R22(sp)
285 		LONG_L	$23, PT_R23(sp)
286 		LONG_L	$30, PT_R30(sp)
287 		.endm
288 
289 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
290 
291 		.macro	RESTORE_SOME
292 		.set	push
293 		.set	reorder
294 		.set	noat
295 		mfc0	a0, CP0_STATUS
296 		li	v1, 0xff00
297 		ori	a0, STATMASK
298 		xori	a0, STATMASK
299 		mtc0	a0, CP0_STATUS
300 		and	a0, v1
301 		LONG_L	v0, PT_STATUS(sp)
302 		nor	v1, $0, v1
303 		and	v0, v1
304 		or	v0, a0
305 		mtc0	v0, CP0_STATUS
306 		LONG_L	$31, PT_R31(sp)
307 		LONG_L	$28, PT_R28(sp)
308 		LONG_L	$25, PT_R25(sp)
309 		LONG_L	$7,  PT_R7(sp)
310 		LONG_L	$6,  PT_R6(sp)
311 		LONG_L	$5,  PT_R5(sp)
312 		LONG_L	$4,  PT_R4(sp)
313 		LONG_L	$3,  PT_R3(sp)
314 		LONG_L	$2,  PT_R2(sp)
315 		.set	pop
316 		.endm
317 
318 		.macro	RESTORE_SP_AND_RET
319 		.set	push
320 		.set	noreorder
321 		LONG_L	k0, PT_EPC(sp)
322 		LONG_L	sp, PT_R29(sp)
323 		jr	k0
324 		 rfe
325 		.set	pop
326 		.endm
327 
328 #else
329 		.macro	RESTORE_SOME
330 		.set	push
331 		.set	reorder
332 		.set	noat
333 #ifdef CONFIG_MIPS_MT_SMTC
334 		.set	mips32r2
335 		/*
336 		 * We need to make sure the read-modify-write
337 		 * of Status below isn't perturbed by an interrupt
338 		 * or cross-TC access, so we need to do at least a DMT,
339 		 * protected by an interrupt-inhibit. But setting IXMT
340 		 * also creates a few-cycle window where an IPI could
341 		 * be queued and not be detected before potentially
342 		 * returning to a WAIT or user-mode loop. It must be
343 		 * replayed.
344 		 *
345 		 * We're in the middle of a context switch, and
346 		 * we can't dispatch it directly without trashing
347 		 * some registers, so we'll try to detect this unlikely
348 		 * case and program a software interrupt in the VPE,
349 		 * as would be done for a cross-VPE IPI.  To accomodate
350 		 * the handling of that case, we're doing a DVPE instead
351 		 * of just a DMT here to protect against other threads.
352 		 * This is a lot of cruft to cover a tiny window.
353 		 * If you can find a better design, implement it!
354 		 *
355 		 */
356 		mfc0	v0, CP0_TCSTATUS
357 		ori	v0, TCSTATUS_IXMT
358 		mtc0	v0, CP0_TCSTATUS
359 		_ehb
360 		DVPE	5				# dvpe a1
361 		jal	mips_ihb
362 #endif /* CONFIG_MIPS_MT_SMTC */
363 #ifdef CONFIG_CPU_CAVIUM_OCTEON
364 		/* Restore the Octeon multiplier state */
365 		jal	octeon_mult_restore
366 #endif
367 		mfc0	a0, CP0_STATUS
368 		ori	a0, STATMASK
369 		xori	a0, STATMASK
370 		mtc0	a0, CP0_STATUS
371 		li	v1, 0xff00
372 		and	a0, v1
373 		LONG_L	v0, PT_STATUS(sp)
374 		nor	v1, $0, v1
375 		and	v0, v1
376 		or	v0, a0
377 		mtc0	v0, CP0_STATUS
378 #ifdef CONFIG_MIPS_MT_SMTC
379 /*
380  * Only after EXL/ERL have been restored to status can we
381  * restore TCStatus.IXMT.
382  */
383 		LONG_L	v1, PT_TCSTATUS(sp)
384 		_ehb
385 		mfc0	a0, CP0_TCSTATUS
386 		andi	v1, TCSTATUS_IXMT
387 		bnez	v1, 0f
388 
389 /*
390  * We'd like to detect any IPIs queued in the tiny window
391  * above and request an software interrupt to service them
392  * when we ERET.
393  *
394  * Computing the offset into the IPIQ array of the executing
395  * TC's IPI queue in-line would be tedious.  We use part of
396  * the TCContext register to hold 16 bits of offset that we
397  * can add in-line to find the queue head.
398  */
399 		mfc0	v0, CP0_TCCONTEXT
400 		la	a2, IPIQ
401 		srl	v0, v0, 16
402 		addu	a2, a2, v0
403 		LONG_L	v0, 0(a2)
404 		beqz	v0, 0f
405 /*
406  * If we have a queue, provoke dispatch within the VPE by setting C_SW1
407  */
408 		mfc0	v0, CP0_CAUSE
409 		ori	v0, v0, C_SW1
410 		mtc0	v0, CP0_CAUSE
411 0:
412 		/*
413 		 * This test should really never branch but
414 		 * let's be prudent here.  Having atomized
415 		 * the shared register modifications, we can
416 		 * now EVPE, and must do so before interrupts
417 		 * are potentially re-enabled.
418 		 */
419 		andi	a1, a1, MVPCONTROL_EVP
420 		beqz	a1, 1f
421 		evpe
422 1:
423 		/* We know that TCStatua.IXMT should be set from above */
424 		xori	a0, a0, TCSTATUS_IXMT
425 		or	a0, a0, v1
426 		mtc0	a0, CP0_TCSTATUS
427 		_ehb
428 
429 		.set	mips0
430 #endif /* CONFIG_MIPS_MT_SMTC */
431 		LONG_L	v1, PT_EPC(sp)
432 		MTC0	v1, CP0_EPC
433 		LONG_L	$31, PT_R31(sp)
434 		LONG_L	$28, PT_R28(sp)
435 		LONG_L	$25, PT_R25(sp)
436 #ifdef CONFIG_64BIT
437 		LONG_L	$8, PT_R8(sp)
438 		LONG_L	$9, PT_R9(sp)
439 #endif
440 		LONG_L	$7,  PT_R7(sp)
441 		LONG_L	$6,  PT_R6(sp)
442 		LONG_L	$5,  PT_R5(sp)
443 		LONG_L	$4,  PT_R4(sp)
444 		LONG_L	$3,  PT_R3(sp)
445 		LONG_L	$2,  PT_R2(sp)
446 		.set	pop
447 		.endm
448 
449 		.macro	RESTORE_SP_AND_RET
450 		LONG_L	sp, PT_R29(sp)
451 		.set	mips3
452 		eret
453 		.set	mips0
454 		.endm
455 
456 #endif
457 
458 		.macro	RESTORE_SP
459 		LONG_L	sp, PT_R29(sp)
460 		.endm
461 
462 		.macro	RESTORE_ALL
463 		RESTORE_TEMP
464 		RESTORE_STATIC
465 		RESTORE_AT
466 		RESTORE_SOME
467 		RESTORE_SP
468 		.endm
469 
470 		.macro	RESTORE_ALL_AND_RET
471 		RESTORE_TEMP
472 		RESTORE_STATIC
473 		RESTORE_AT
474 		RESTORE_SOME
475 		RESTORE_SP_AND_RET
476 		.endm
477 
478 /*
479  * Move to kernel mode and disable interrupts.
480  * Set cp0 enable bit as sign that we're running on the kernel stack
481  */
482 		.macro	CLI
483 #if !defined(CONFIG_MIPS_MT_SMTC)
484 		mfc0	t0, CP0_STATUS
485 		li	t1, ST0_CU0 | STATMASK
486 		or	t0, t1
487 		xori	t0, STATMASK
488 		mtc0	t0, CP0_STATUS
489 #else /* CONFIG_MIPS_MT_SMTC */
490 		/*
491 		 * For SMTC, we need to set privilege
492 		 * and disable interrupts only for the
493 		 * current TC, using the TCStatus register.
494 		 */
495 		mfc0	t0, CP0_TCSTATUS
496 		/* Fortunately CU 0 is in the same place in both registers */
497 		/* Set TCU0, TMX, TKSU (for later inversion) and IXMT */
498 		li	t1, ST0_CU0 | 0x08001c00
499 		or	t0, t1
500 		/* Clear TKSU, leave IXMT */
501 		xori	t0, 0x00001800
502 		mtc0	t0, CP0_TCSTATUS
503 		_ehb
504 		/* We need to leave the global IE bit set, but clear EXL...*/
505 		mfc0	t0, CP0_STATUS
506 		ori	t0, ST0_EXL | ST0_ERL
507 		xori	t0, ST0_EXL | ST0_ERL
508 		mtc0	t0, CP0_STATUS
509 #endif /* CONFIG_MIPS_MT_SMTC */
510 		irq_disable_hazard
511 		.endm
512 
513 /*
514  * Move to kernel mode and enable interrupts.
515  * Set cp0 enable bit as sign that we're running on the kernel stack
516  */
517 		.macro	STI
518 #if !defined(CONFIG_MIPS_MT_SMTC)
519 		mfc0	t0, CP0_STATUS
520 		li	t1, ST0_CU0 | STATMASK
521 		or	t0, t1
522 		xori	t0, STATMASK & ~1
523 		mtc0	t0, CP0_STATUS
524 #else /* CONFIG_MIPS_MT_SMTC */
525 		/*
526 		 * For SMTC, we need to set privilege
527 		 * and enable interrupts only for the
528 		 * current TC, using the TCStatus register.
529 		 */
530 		_ehb
531 		mfc0	t0, CP0_TCSTATUS
532 		/* Fortunately CU 0 is in the same place in both registers */
533 		/* Set TCU0, TKSU (for later inversion) and IXMT */
534 		li	t1, ST0_CU0 | 0x08001c00
535 		or	t0, t1
536 		/* Clear TKSU *and* IXMT */
537 		xori	t0, 0x00001c00
538 		mtc0	t0, CP0_TCSTATUS
539 		_ehb
540 		/* We need to leave the global IE bit set, but clear EXL...*/
541 		mfc0	t0, CP0_STATUS
542 		ori	t0, ST0_EXL
543 		xori	t0, ST0_EXL
544 		mtc0	t0, CP0_STATUS
545 		/* irq_enable_hazard below should expand to EHB for 24K/34K cpus */
546 #endif /* CONFIG_MIPS_MT_SMTC */
547 		irq_enable_hazard
548 		.endm
549 
550 /*
551  * Just move to kernel mode and leave interrupts as they are.  Note
552  * for the R3000 this means copying the previous enable from IEp.
553  * Set cp0 enable bit as sign that we're running on the kernel stack
554  */
555 		.macro	KMODE
556 #ifdef CONFIG_MIPS_MT_SMTC
557 		/*
558 		 * This gets baroque in SMTC.  We want to
559 		 * protect the non-atomic clearing of EXL
560 		 * with DMT/EMT, but we don't want to take
561 		 * an interrupt while DMT is still in effect.
562 		 */
563 
564 		/* KMODE gets invoked from both reorder and noreorder code */
565 		.set	push
566 		.set	mips32r2
567 		.set	noreorder
568 		mfc0	v0, CP0_TCSTATUS
569 		andi	v1, v0, TCSTATUS_IXMT
570 		ori	v0, TCSTATUS_IXMT
571 		mtc0	v0, CP0_TCSTATUS
572 		_ehb
573 		DMT	2				# dmt	v0
574 		/*
575 		 * We don't know a priori if ra is "live"
576 		 */
577 		move	t0, ra
578 		jal	mips_ihb
579 		nop	/* delay slot */
580 		move	ra, t0
581 #endif /* CONFIG_MIPS_MT_SMTC */
582 		mfc0	t0, CP0_STATUS
583 		li	t1, ST0_CU0 | (STATMASK & ~1)
584 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
585 		andi	t2, t0, ST0_IEP
586 		srl	t2, 2
587 		or	t0, t2
588 #endif
589 		or	t0, t1
590 		xori	t0, STATMASK & ~1
591 		mtc0	t0, CP0_STATUS
592 #ifdef CONFIG_MIPS_MT_SMTC
593 		_ehb
594 		andi	v0, v0, VPECONTROL_TE
595 		beqz	v0, 2f
596 		nop	/* delay slot */
597 		emt
598 2:
599 		mfc0	v0, CP0_TCSTATUS
600 		/* Clear IXMT, then OR in previous value */
601 		ori	v0, TCSTATUS_IXMT
602 		xori	v0, TCSTATUS_IXMT
603 		or	v0, v1, v0
604 		mtc0	v0, CP0_TCSTATUS
605 		/*
606 		 * irq_disable_hazard below should expand to EHB
607 		 * on 24K/34K CPUS
608 		 */
609 		.set pop
610 #endif /* CONFIG_MIPS_MT_SMTC */
611 		irq_disable_hazard
612 		.endm
613 
614 #endif /* _ASM_STACKFRAME_H */
615