cpuswitch.S revision 1.22 1 1.22 bjh21 /* $NetBSD: cpuswitch.S,v 1.22 2002/10/12 12:20:10 bjh21 Exp $ */
2 1.1 chris
3 1.1 chris /*
4 1.1 chris * Copyright (c) 1994-1998 Mark Brinicombe.
5 1.1 chris * Copyright (c) 1994 Brini.
6 1.1 chris * All rights reserved.
7 1.1 chris *
8 1.1 chris * This code is derived from software written for Brini by Mark Brinicombe
9 1.1 chris *
10 1.1 chris * Redistribution and use in source and binary forms, with or without
11 1.1 chris * modification, are permitted provided that the following conditions
12 1.1 chris * are met:
13 1.1 chris * 1. Redistributions of source code must retain the above copyright
14 1.1 chris * notice, this list of conditions and the following disclaimer.
15 1.1 chris * 2. Redistributions in binary form must reproduce the above copyright
16 1.1 chris * notice, this list of conditions and the following disclaimer in the
17 1.1 chris * documentation and/or other materials provided with the distribution.
18 1.1 chris * 3. All advertising materials mentioning features or use of this software
19 1.1 chris * must display the following acknowledgement:
20 1.1 chris * This product includes software developed by Brini.
21 1.1 chris * 4. The name of the company nor the name of the author may be used to
22 1.1 chris * endorse or promote products derived from this software without specific
23 1.1 chris * prior written permission.
24 1.1 chris *
25 1.1 chris * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
26 1.1 chris * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
27 1.1 chris * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 1.1 chris * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
29 1.1 chris * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
30 1.1 chris * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
31 1.1 chris * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 1.1 chris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 1.1 chris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 1.1 chris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 1.1 chris * SUCH DAMAGE.
36 1.1 chris *
37 1.1 chris * RiscBSD kernel project
38 1.1 chris *
39 1.1 chris * cpuswitch.S
40 1.1 chris *
41 1.1 chris * cpu switching functions
42 1.1 chris *
43 1.1 chris * Created : 15/10/94
44 1.1 chris */
45 1.1 chris
46 1.1 chris #include "opt_armfpe.h"
47 1.19 bjh21 #include "opt_multiprocessor.h"
48 1.1 chris
49 1.1 chris #include "assym.h"
50 1.1 chris #include <machine/param.h>
51 1.1 chris #include <machine/cpu.h>
52 1.1 chris #include <machine/frame.h>
53 1.1 chris #include <machine/asm.h>
54 1.1 chris
55 1.1 chris #undef IRQdisable
56 1.1 chris #undef IRQenable
57 1.1 chris
58 1.1 chris /*
59 1.1 chris * New experimental definitions of IRQdisable and IRQenable
60 1.1 chris * These keep FIQ's enabled since FIQ's are special.
61 1.1 chris */
62 1.1 chris
63 1.1 chris #define IRQdisable \
64 1.13 thorpej mrs r14, cpsr ; \
65 1.1 chris orr r14, r14, #(I32_bit) ; \
66 1.13 thorpej msr cpsr_c, r14 ; \
67 1.1 chris
68 1.1 chris #define IRQenable \
69 1.13 thorpej mrs r14, cpsr ; \
70 1.1 chris bic r14, r14, #(I32_bit) ; \
71 1.13 thorpej msr cpsr_c, r14 ; \
72 1.1 chris
73 1.1 chris /*
74 1.1 chris * setrunqueue() and remrunqueue()
75 1.1 chris *
76 1.1 chris * Functions to add and remove a process for the run queue.
77 1.1 chris */
78 1.1 chris
79 1.1 chris .text
80 1.1 chris
81 1.17 thorpej .Lwhichqs:
82 1.1 chris .word _C_LABEL(sched_whichqs)
83 1.1 chris
84 1.17 thorpej .Lqs:
85 1.1 chris .word _C_LABEL(sched_qs)
86 1.1 chris
87 1.1 chris /*
88 1.1 chris * On entry
89 1.1 chris * r0 = process
90 1.1 chris */
91 1.1 chris
92 1.1 chris ENTRY(setrunqueue)
93 1.1 chris /*
94 1.1 chris * Local register usage
95 1.1 chris * r0 = process
96 1.1 chris * r1 = queue
97 1.1 chris * r2 = &qs[queue] and temp
98 1.1 chris * r3 = temp
99 1.1 chris * r12 = whichqs
100 1.1 chris */
101 1.1 chris #ifdef DIAGNOSTIC
102 1.1 chris ldr r1, [r0, #(P_BACK)]
103 1.1 chris teq r1, #0x00000000
104 1.14 briggs bne .Lsetrunqueue_erg
105 1.1 chris
106 1.1 chris ldr r1, [r0, #(P_WCHAN)]
107 1.1 chris teq r1, #0x00000000
108 1.14 briggs bne .Lsetrunqueue_erg
109 1.1 chris #endif
110 1.1 chris
111 1.1 chris /* Get the priority of the queue */
112 1.1 chris ldrb r1, [r0, #(P_PRIORITY)]
113 1.1 chris
114 1.1 chris /* Indicate that there is a process on this queue */
115 1.17 thorpej ldr r12, .Lwhichqs
116 1.12 chris mov r1, r1, lsr #2
117 1.1 chris ldr r2, [r12]
118 1.1 chris mov r3, #0x00000001
119 1.1 chris mov r3, r3, lsl r1
120 1.1 chris orr r2, r2, r3
121 1.1 chris str r2, [r12]
122 1.1 chris
123 1.1 chris /* Get the address of the queue */
124 1.17 thorpej ldr r2, .Lqs
125 1.1 chris add r1, r2, r1, lsl # 3
126 1.1 chris
127 1.1 chris /* Hook the process in */
128 1.1 chris str r1, [r0, #(P_FORW)]
129 1.1 chris ldr r2, [r1, #(P_BACK)]
130 1.1 chris
131 1.1 chris str r0, [r1, #(P_BACK)]
132 1.1 chris #ifdef DIAGNOSTIC
133 1.1 chris teq r2, #0x00000000
134 1.14 briggs beq .Lsetrunqueue_erg
135 1.1 chris #endif
136 1.1 chris str r0, [r2, #(P_FORW)]
137 1.1 chris str r2, [r0, #(P_BACK)]
138 1.1 chris
139 1.1 chris mov pc, lr
140 1.1 chris
141 1.1 chris #ifdef DIAGNOSTIC
142 1.14 briggs .Lsetrunqueue_erg:
143 1.1 chris mov r2, r1
144 1.1 chris mov r1, r0
145 1.17 thorpej add r0, pc, #.Ltext1 - . - 8
146 1.1 chris bl _C_LABEL(printf)
147 1.1 chris
148 1.17 thorpej ldr r2, .Lqs
149 1.1 chris ldr r1, [r2]
150 1.17 thorpej add r0, pc, #.Ltext2 - . - 8
151 1.1 chris b _C_LABEL(panic)
152 1.1 chris
153 1.17 thorpej .Ltext1:
154 1.1 chris .asciz "setrunqueue : %08x %08x\n"
155 1.17 thorpej .Ltext2:
156 1.1 chris .asciz "setrunqueue : [qs]=%08x qs=%08x\n"
157 1.1 chris .align 0
158 1.1 chris #endif
159 1.1 chris
160 1.1 chris /*
161 1.1 chris * On entry
162 1.1 chris * r0 = process
163 1.1 chris */
164 1.1 chris
165 1.1 chris ENTRY(remrunqueue)
166 1.1 chris /*
167 1.1 chris * Local register usage
168 1.1 chris * r0 = oldproc
169 1.1 chris * r1 = queue
170 1.1 chris * r2 = &qs[queue] and scratch
171 1.1 chris * r3 = scratch
172 1.1 chris * r12 = whichqs
173 1.1 chris */
174 1.1 chris
175 1.1 chris /* Get the priority of the queue */
176 1.1 chris ldrb r1, [r0, #(P_PRIORITY)]
177 1.1 chris mov r1, r1, lsr #2
178 1.1 chris
179 1.1 chris /* Unhook the process */
180 1.1 chris ldr r2, [r0, #(P_FORW)]
181 1.1 chris ldr r3, [r0, #(P_BACK)]
182 1.1 chris
183 1.1 chris str r3, [r2, #(P_BACK)]
184 1.1 chris str r2, [r3, #(P_FORW)]
185 1.1 chris
186 1.1 chris /* If the queue is now empty clear the queue not empty flag */
187 1.1 chris teq r2, r3
188 1.1 chris
189 1.1 chris /* This could be reworked to avoid the use of r4 */
190 1.17 thorpej ldreq r12, .Lwhichqs
191 1.12 chris moveq r3, #0x00000001
192 1.1 chris ldreq r2, [r12]
193 1.1 chris moveq r3, r3, lsl r1
194 1.1 chris biceq r2, r2, r3
195 1.1 chris streq r2, [r12]
196 1.1 chris
197 1.1 chris /* Remove the back pointer for the process */
198 1.1 chris mov r1, #0x00000000
199 1.1 chris str r1, [r0, #(P_BACK)]
200 1.1 chris
201 1.1 chris mov pc, lr
202 1.1 chris
203 1.1 chris
204 1.1 chris /*
205 1.1 chris * cpuswitch()
206 1.1 chris *
207 1.1 chris * preforms a process context switch.
208 1.1 chris * This function has several entry points
209 1.1 chris */
210 1.1 chris
211 1.19 bjh21 #ifdef MULTIPROCESSOR
212 1.19 bjh21 .Lcpu_info_store:
213 1.19 bjh21 .word _C_LABEL(cpu_info_store)
214 1.19 bjh21 .Lcurproc:
215 1.19 bjh21 /* FIXME: This is bogus in the general case. */
216 1.19 bjh21 .word _C_LABEL(cpu_info_store) + CI_CURPROC
217 1.22 bjh21
218 1.22 bjh21 .Lcurpcb:
219 1.22 bjh21 .word _C_LABEL(cpu_info_store) + CI_CURPCB
220 1.19 bjh21 #else
221 1.17 thorpej .Lcurproc:
222 1.1 chris .word _C_LABEL(curproc)
223 1.1 chris
224 1.17 thorpej .Lcurpcb:
225 1.1 chris .word _C_LABEL(curpcb)
226 1.22 bjh21 #endif
227 1.1 chris
228 1.17 thorpej .Lwant_resched:
229 1.1 chris .word _C_LABEL(want_resched)
230 1.1 chris
231 1.17 thorpej .Lcpufuncs:
232 1.1 chris .word _C_LABEL(cpufuncs)
233 1.1 chris
234 1.22 bjh21 #ifndef MULTIPROCESSOR
235 1.1 chris .data
236 1.1 chris .global _C_LABEL(curpcb)
237 1.1 chris _C_LABEL(curpcb):
238 1.1 chris .word 0x00000000
239 1.1 chris .text
240 1.22 bjh21 #endif
241 1.1 chris
242 1.17 thorpej .Lblock_userspace_access:
243 1.1 chris .word _C_LABEL(block_userspace_access)
244 1.1 chris
245 1.15 thorpej .Lcpu_do_powersave:
246 1.15 thorpej .word _C_LABEL(cpu_do_powersave)
247 1.15 thorpej
248 1.1 chris /*
249 1.1 chris * Idle loop, exercised while waiting for a process to wake up.
250 1.16 thorpej *
251 1.16 thorpej * NOTE: When we jump back to .Lswitch_search, we must have a
252 1.16 thorpej * pointer to whichqs in r7, which is what it is when we arrive
253 1.16 thorpej * here.
254 1.1 chris */
255 1.7 chris /* LINTSTUB: Ignore */
256 1.4 chris ASENTRY_NP(idle)
257 1.19 bjh21 #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
258 1.7 chris bl _C_LABEL(sched_unlock_idle)
259 1.7 chris #endif
260 1.16 thorpej ldr r3, .Lcpu_do_powersave
261 1.16 thorpej
262 1.1 chris /* Enable interrupts */
263 1.1 chris IRQenable
264 1.1 chris
265 1.15 thorpej /* If we don't want to sleep, use a simpler loop. */
266 1.16 thorpej ldr r3, [r3] /* r3 = cpu_do_powersave */
267 1.15 thorpej teq r3, #0
268 1.16 thorpej bne 2f
269 1.16 thorpej
270 1.16 thorpej /* Non-powersave idle. */
271 1.16 thorpej 1: /* should maybe do uvm pageidlezero stuff here */
272 1.16 thorpej ldr r3, [r7] /* r3 = whichqs */
273 1.16 thorpej teq r3, #0x00000000
274 1.16 thorpej bne .Lswitch_search
275 1.16 thorpej b 1b
276 1.15 thorpej
277 1.16 thorpej 2: /* Powersave idle. */
278 1.17 thorpej ldr r4, .Lcpufuncs
279 1.16 thorpej 3: ldr r3, [r7] /* r3 = whichqs */
280 1.15 thorpej teq r3, #0x00000000
281 1.15 thorpej bne .Lswitch_search
282 1.15 thorpej
283 1.15 thorpej /* if saving power, don't want to pageidlezero */
284 1.1 chris mov r0, #0
285 1.21 bjh21 adr lr, 3b
286 1.15 thorpej ldr pc, [r4, #(CF_SLEEP)]
287 1.15 thorpej /* loops back around */
288 1.15 thorpej
289 1.1 chris
290 1.1 chris /*
291 1.1 chris * Find a new process to run, save the current context and
292 1.1 chris * load the new context
293 1.1 chris */
294 1.1 chris
295 1.1 chris ENTRY(cpu_switch)
296 1.1 chris /*
297 1.1 chris * Local register usage. Some of these registers are out of date.
298 1.1 chris * r1 = oldproc
299 1.1 chris * r3 = whichqs
300 1.1 chris * r4 = queue
301 1.1 chris * r5 = &qs[queue]
302 1.1 chris * r6 = newproc
303 1.1 chris * r7 = scratch
304 1.1 chris */
305 1.1 chris stmfd sp!, {r4-r7, lr}
306 1.1 chris
307 1.1 chris /*
308 1.1 chris * Get the current process and indicate that there is no longer
309 1.11 thorpej * a valid process (curproc = 0). Zero the current PCB pointer
310 1.11 thorpej * while we're at it.
311 1.1 chris */
312 1.17 thorpej ldr r7, .Lcurproc
313 1.17 thorpej ldr r6, .Lcurpcb
314 1.1 chris mov r0, #0x00000000
315 1.11 thorpej ldr r1, [r7] /* r1 = curproc */
316 1.11 thorpej str r0, [r7] /* curproc = NULL */
317 1.11 thorpej str r0, [r6] /* curpcb = NULL */
318 1.1 chris
319 1.10 thorpej /* stash the old proc while we call functions */
320 1.10 thorpej mov r5, r1
321 1.1 chris
322 1.19 bjh21 #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
323 1.7 chris /* release the sched_lock before handling interrupts */
324 1.7 chris bl _C_LABEL(sched_unlock_idle)
325 1.7 chris #endif
326 1.7 chris
327 1.7 chris /* Lower the spl level to spl0 and get the current spl level. */
328 1.5 thorpej #ifdef __NEWINTR
329 1.5 thorpej mov r0, #(IPL_NONE)
330 1.5 thorpej bl _C_LABEL(_spllower)
331 1.5 thorpej #else /* ! __NEWINTR */
332 1.1 chris #ifdef spl0
333 1.1 chris mov r0, #(_SPL_0)
334 1.1 chris bl _C_LABEL(splx)
335 1.1 chris #else
336 1.1 chris bl _C_LABEL(spl0)
337 1.5 thorpej #endif /* spl0 */
338 1.5 thorpej #endif /* __NEWINTR */
339 1.1 chris
340 1.1 chris /* Push the old spl level onto the stack */
341 1.1 chris str r0, [sp, #-0x0004]!
342 1.1 chris
343 1.1 chris /* First phase : find a new process */
344 1.1 chris
345 1.17 thorpej ldr r7, .Lwhichqs
346 1.16 thorpej
347 1.7 chris /* rem: r5 = old proc */
348 1.16 thorpej /* rem: r7 = &whichqs */
349 1.7 chris
350 1.14 briggs .Lswitch_search:
351 1.1 chris IRQdisable
352 1.19 bjh21 #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
353 1.7 chris bl _C_LABEL(sched_lock_idle)
354 1.7 chris #endif
355 1.7 chris
356 1.1 chris /* Do we have any active queues */
357 1.1 chris ldr r3, [r7]
358 1.1 chris
359 1.1 chris /* If not we must idle until we do. */
360 1.1 chris teq r3, #0x00000000
361 1.4 chris beq _ASM_LABEL(idle)
362 1.7 chris
363 1.10 thorpej /* put old proc back in r1 */
364 1.7 chris mov r1, r5
365 1.1 chris
366 1.1 chris /* rem: r1 = old proc */
367 1.1 chris /* rem: r3 = whichqs */
368 1.1 chris /* rem: interrupts are disabled */
369 1.1 chris
370 1.1 chris /*
371 1.1 chris * We have found an active queue. Currently we do not know which queue
372 1.1 chris * is active just that one of them is.
373 1.1 chris */
374 1.1 chris /* this is the ffs algorithm devised by d.seal and posted to
375 1.1 chris * comp.sys.arm on 16 Feb 1994.
376 1.1 chris */
377 1.1 chris rsb r5, r3, #0
378 1.1 chris ands r0, r3, r5
379 1.1 chris
380 1.17 thorpej adr r5, .Lcpu_switch_ffs_table
381 1.1 chris
382 1.3 chris /* X = R0 */
383 1.3 chris orr r4, r0, r0, lsl #4 /* r4 = X * 0x11 */
384 1.3 chris orr r4, r4, r4, lsl #6 /* r4 = X * 0x451 */
385 1.3 chris rsb r4, r4, r4, lsl #16 /* r4 = X * 0x0450fbaf */
386 1.1 chris
387 1.1 chris /* used further down, saves SA stall */
388 1.17 thorpej ldr r6, .Lqs
389 1.1 chris
390 1.3 chris /* now lookup in table indexed on top 6 bits of a4 */
391 1.1 chris ldrb r4, [ r5, r4, lsr #26 ]
392 1.1 chris
393 1.1 chris /* rem: r0 = bit mask of chosen queue (1 << r4) */
394 1.1 chris /* rem: r1 = old proc */
395 1.1 chris /* rem: r3 = whichqs */
396 1.1 chris /* rem: r4 = queue number */
397 1.1 chris /* rem: interrupts are disabled */
398 1.1 chris
399 1.1 chris /* Get the address of the queue (&qs[queue]) */
400 1.1 chris add r5, r6, r4, lsl #3
401 1.1 chris
402 1.1 chris /*
403 1.1 chris * Get the process from the queue and place the next process in
404 1.1 chris * the queue at the head. This basically unlinks the process at
405 1.1 chris * the head of the queue.
406 1.1 chris */
407 1.1 chris ldr r6, [r5, #(P_FORW)]
408 1.1 chris
409 1.1 chris /* rem: r6 = new process */
410 1.1 chris ldr r7, [r6, #(P_FORW)]
411 1.1 chris str r7, [r5, #(P_FORW)]
412 1.1 chris
413 1.1 chris /*
414 1.1 chris * Test to see if the queue is now empty. If the head of the queue
415 1.1 chris * points to the queue itself then there are no more processes in
416 1.1 chris * the queue. We can therefore clear the queue not empty flag held
417 1.1 chris * in r3.
418 1.1 chris */
419 1.1 chris
420 1.1 chris teq r5, r7
421 1.1 chris biceq r3, r3, r0
422 1.1 chris
423 1.1 chris /* rem: r0 = bit mask of chosen queue (1 << r4) - NOT NEEDED AN MORE */
424 1.1 chris
425 1.1 chris /* Fix the back pointer for the process now at the head of the queue. */
426 1.1 chris ldr r0, [r6, #(P_BACK)]
427 1.1 chris str r0, [r7, #(P_BACK)]
428 1.1 chris
429 1.1 chris /* Update the RAM copy of the queue not empty flags word. */
430 1.17 thorpej ldr r7, .Lwhichqs
431 1.1 chris str r3, [r7]
432 1.1 chris
433 1.1 chris /* rem: r1 = old proc */
434 1.1 chris /* rem: r3 = whichqs - NOT NEEDED ANY MORE */
435 1.1 chris /* rem: r4 = queue number - NOT NEEDED ANY MORE */
436 1.1 chris /* rem: r6 = new process */
437 1.1 chris /* rem: interrupts are disabled */
438 1.1 chris
439 1.1 chris /* Clear the want_resched flag */
440 1.17 thorpej ldr r7, .Lwant_resched
441 1.1 chris mov r0, #0x00000000
442 1.1 chris str r0, [r7]
443 1.1 chris
444 1.1 chris /*
445 1.1 chris * Clear the back pointer of the process we have removed from
446 1.1 chris * the head of the queue. The new process is isolated now.
447 1.1 chris */
448 1.1 chris str r0, [r6, #(P_BACK)]
449 1.1 chris
450 1.19 bjh21 #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
451 1.7 chris /*
452 1.7 chris * unlock the sched_lock, but leave interrupts off, for now.
453 1.7 chris */
454 1.7 chris mov r7, r1
455 1.7 chris bl _C_LABEL(sched_unlock_idle)
456 1.7 chris mov r1, r7
457 1.7 chris #endif
458 1.7 chris
459 1.19 bjh21 #ifdef MULTIPROCESSOR
460 1.19 bjh21 /* XXX use curcpu() */
461 1.19 bjh21 ldr r0, .Lcpu_info_store
462 1.19 bjh21 str r0, [r6, #(P_CPU)]
463 1.19 bjh21 #else
464 1.1 chris /* p->p_cpu initialized in fork1() for single-processor */
465 1.19 bjh21 #endif
466 1.1 chris
467 1.1 chris /* Process is now on a processor. */
468 1.1 chris mov r0, #SONPROC /* p->p_stat = SONPROC */
469 1.1 chris strb r0, [r6, #(P_STAT)]
470 1.1 chris
471 1.1 chris /* We have a new curproc now so make a note it */
472 1.17 thorpej ldr r7, .Lcurproc
473 1.1 chris str r6, [r7]
474 1.1 chris
475 1.1 chris /* Hook in a new pcb */
476 1.17 thorpej ldr r7, .Lcurpcb
477 1.1 chris ldr r0, [r6, #(P_ADDR)]
478 1.1 chris str r0, [r7]
479 1.1 chris
480 1.1 chris /* At this point we can allow IRQ's again. */
481 1.1 chris IRQenable
482 1.1 chris
483 1.1 chris /* rem: r1 = old proc */
484 1.1 chris /* rem: r6 = new process */
485 1.4 chris /* rem: interrupts are enabled */
486 1.1 chris
487 1.1 chris /*
488 1.1 chris * If the new process is the same as the process that called
489 1.1 chris * cpu_switch() then we do not need to save and restore any
490 1.1 chris * contexts. This means we can make a quick exit.
491 1.1 chris * The test is simple if curproc on entry (now in r1) is the
492 1.1 chris * same as the proc removed from the queue we can jump to the exit.
493 1.1 chris */
494 1.1 chris teq r1, r6
495 1.14 briggs beq .Lswitch_return
496 1.1 chris
497 1.9 thorpej /* Remember the old process in r0 */
498 1.9 thorpej mov r0, r1
499 1.9 thorpej
500 1.1 chris /*
501 1.1 chris * If the curproc on entry to cpu_switch was zero then the
502 1.1 chris * process that called it was exiting. This means that we do
503 1.1 chris * not need to save the current context. Instead we can jump
504 1.1 chris * straight to restoring the context for the new process.
505 1.1 chris */
506 1.9 thorpej teq r0, #0x00000000
507 1.14 briggs beq .Lswitch_exited
508 1.1 chris
509 1.9 thorpej /* rem: r0 = old proc */
510 1.1 chris /* rem: r6 = new process */
511 1.4 chris /* rem: interrupts are enabled */
512 1.1 chris
513 1.1 chris /* Stage two : Save old context */
514 1.1 chris
515 1.1 chris /* Get the user structure for the old process. */
516 1.9 thorpej ldr r1, [r0, #(P_ADDR)]
517 1.1 chris
518 1.1 chris /* Save all the registers in the old process's pcb */
519 1.1 chris add r7, r1, #(PCB_R8)
520 1.1 chris stmia r7, {r8-r13}
521 1.1 chris
522 1.1 chris /*
523 1.1 chris * This can be optimised... We know we want to go from SVC32
524 1.1 chris * mode to UND32 mode
525 1.1 chris */
526 1.13 thorpej mrs r3, cpsr
527 1.1 chris bic r2, r3, #(PSR_MODE)
528 1.1 chris orr r2, r2, #(PSR_UND32_MODE | I32_bit)
529 1.13 thorpej msr cpsr_c, r2
530 1.1 chris
531 1.1 chris str sp, [r1, #(PCB_UND_SP)]
532 1.1 chris
533 1.13 thorpej msr cpsr_c, r3 /* Restore the old mode */
534 1.1 chris
535 1.1 chris /* rem: r0 = old proc */
536 1.4 chris /* rem: r1 = old pcb */
537 1.1 chris /* rem: r6 = new process */
538 1.4 chris /* rem: interrupts are enabled */
539 1.1 chris
540 1.1 chris /* What else needs to be saved Only FPA stuff when that is supported */
541 1.1 chris
542 1.9 thorpej /* r1 now free! */
543 1.9 thorpej
544 1.1 chris /* Third phase : restore saved context */
545 1.1 chris
546 1.9 thorpej /* rem: r0 = old proc */
547 1.9 thorpej /* rem: r6 = new process */
548 1.9 thorpej /* rem: interrupts are enabled */
549 1.9 thorpej
550 1.9 thorpej /*
551 1.9 thorpej * Don't allow user space access between the purge and the switch.
552 1.9 thorpej */
553 1.17 thorpej ldr r3, .Lblock_userspace_access
554 1.9 thorpej mov r1, #0x00000001
555 1.9 thorpej mov r2, #0x00000000
556 1.9 thorpej str r1, [r3]
557 1.1 chris
558 1.1 chris stmfd sp!, {r0-r3}
559 1.17 thorpej ldr r1, .Lcpufuncs
560 1.14 briggs add lr, pc, #.Lcs_cache_purged - . - 8
561 1.9 thorpej ldr pc, [r1, #CF_IDCACHE_WBINV_ALL]
562 1.1 chris
563 1.14 briggs .Lcs_cache_purged:
564 1.1 chris ldmfd sp!, {r0-r3}
565 1.1 chris
566 1.14 briggs .Lcs_cache_purge_skipped:
567 1.1 chris /* At this point we need to kill IRQ's again. */
568 1.1 chris IRQdisable
569 1.1 chris
570 1.9 thorpej /*
571 1.9 thorpej * Interrupts are disabled so we can allow user space accesses again
572 1.1 chris * as none will occur until interrupts are re-enabled after the
573 1.1 chris * switch.
574 1.1 chris */
575 1.1 chris str r2, [r3]
576 1.1 chris
577 1.1 chris /* Get the user structure for the new process in r1 */
578 1.1 chris ldr r1, [r6, #(P_ADDR)]
579 1.1 chris
580 1.1 chris /* Get the pagedir physical address for the process. */
581 1.1 chris ldr r0, [r1, #(PCB_PAGEDIR)]
582 1.1 chris
583 1.1 chris /* Switch the memory to the new process */
584 1.17 thorpej ldr r3, .Lcpufuncs
585 1.14 briggs add lr, pc, #.Lcs_context_switched - . - 8
586 1.1 chris ldr pc, [r3, #CF_CONTEXT_SWITCH]
587 1.1 chris
588 1.14 briggs .Lcs_context_switched:
589 1.1 chris /*
590 1.1 chris * This can be optimised... We know we want to go from SVC32
591 1.1 chris * mode to UND32 mode
592 1.1 chris */
593 1.13 thorpej mrs r3, cpsr
594 1.1 chris bic r2, r3, #(PSR_MODE)
595 1.1 chris orr r2, r2, #(PSR_UND32_MODE)
596 1.13 thorpej msr cpsr_c, r2
597 1.1 chris
598 1.1 chris ldr sp, [r1, #(PCB_UND_SP)]
599 1.1 chris
600 1.13 thorpej msr cpsr_c, r3 /* Restore the old mode */
601 1.1 chris
602 1.1 chris /* Restore all the save registers */
603 1.1 chris add r7, r1, #PCB_R8
604 1.1 chris ldmia r7, {r8-r13}
605 1.1 chris
606 1.18 thorpej mov r7, r1 /* preserve PCB pointer */
607 1.18 thorpej
608 1.1 chris #ifdef ARMFPE
609 1.1 chris add r0, r1, #(USER_SIZE) & 0x00ff
610 1.1 chris add r0, r0, #(USER_SIZE) & 0xff00
611 1.1 chris bl _C_LABEL(arm_fpe_core_changecontext)
612 1.1 chris #endif
613 1.1 chris
614 1.1 chris /* We can enable interrupts again */
615 1.1 chris IRQenable
616 1.1 chris
617 1.18 thorpej /* rem: r6 = new proc */
618 1.18 thorpej /* rem: r7 = new PCB */
619 1.18 thorpej
620 1.18 thorpej /*
621 1.18 thorpej * Check for restartable atomic sequences (RAS).
622 1.18 thorpej */
623 1.18 thorpej
624 1.18 thorpej ldr r2, [r6, #(P_NRAS)]
625 1.18 thorpej ldr r4, [r7, #(PCB_TF)] /* r4 = trapframe (used below) */
626 1.18 thorpej teq r2, #0 /* p->p_nras == 0? */
627 1.18 thorpej bne .Lswitch_do_ras /* no, check for one */
628 1.18 thorpej
629 1.14 briggs .Lswitch_return:
630 1.1 chris
631 1.1 chris /* Get the spl level from the stack and update the current spl level */
632 1.1 chris ldr r0, [sp], #0x0004
633 1.1 chris bl _C_LABEL(splx)
634 1.1 chris
635 1.1 chris /* cpu_switch returns the proc it switched to. */
636 1.1 chris mov r0, r6
637 1.1 chris
638 1.1 chris /*
639 1.1 chris * Pull the registers that got pushed when either savectx() or
640 1.1 chris * cpu_switch() was called and return.
641 1.1 chris */
642 1.1 chris ldmfd sp!, {r4-r7, pc}
643 1.18 thorpej
644 1.18 thorpej .Lswitch_do_ras:
645 1.18 thorpej ldr r1, [r4, #(TF_PC)] /* second ras_lookup() arg */
646 1.18 thorpej mov r0, r6 /* first ras_lookup() arg */
647 1.18 thorpej bl _C_LABEL(ras_lookup)
648 1.18 thorpej cmn r0, #1 /* -1 means "not in a RAS" */
649 1.18 thorpej strne r0, [r4, #(TF_PC)]
650 1.18 thorpej b .Lswitch_return
651 1.1 chris
652 1.14 briggs .Lswitch_exited:
653 1.9 thorpej /*
654 1.9 thorpej * We skip the cache purge because switch_exit() already did
655 1.9 thorpej * it. Load up registers the way Lcs_cache_purge_skipped
656 1.9 thorpej * expects. Userspace access already blocked in switch_exit().
657 1.9 thorpej */
658 1.17 thorpej ldr r3, .Lblock_userspace_access
659 1.9 thorpej mov r2, #0x00000000
660 1.14 briggs b .Lcs_cache_purge_skipped
661 1.9 thorpej
662 1.7 chris /*
663 1.8 thorpej * void switch_exit(struct proc *p, struct proc *p0);
664 1.7 chris * Switch to proc0's saved context and deallocate the address space and kernel
665 1.7 chris * stack for p. Then jump into cpu_switch(), as if we were in proc0 all along.
666 1.7 chris */
667 1.1 chris
668 1.8 thorpej /* LINTSTUB: Func: void switch_exit(struct proc *p, struct proc *p0) */
669 1.1 chris ENTRY(switch_exit)
670 1.1 chris /*
671 1.1 chris * r0 = proc
672 1.1 chris * r1 = proc0
673 1.1 chris */
674 1.1 chris
675 1.1 chris mov r3, r0
676 1.1 chris
677 1.1 chris /* In case we fault */
678 1.17 thorpej ldr r0, .Lcurproc
679 1.1 chris mov r2, #0x00000000
680 1.1 chris str r2, [r0]
681 1.1 chris
682 1.17 thorpej /* ldr r0, .Lcurpcb
683 1.1 chris str r2, [r0]*/
684 1.9 thorpej
685 1.9 thorpej /*
686 1.9 thorpej * Don't allow user space access between the purge and the switch.
687 1.9 thorpej */
688 1.17 thorpej ldr r0, .Lblock_userspace_access
689 1.9 thorpej mov r2, #0x00000001
690 1.9 thorpej str r2, [r0]
691 1.1 chris
692 1.1 chris /* Switch to proc0 context */
693 1.1 chris
694 1.1 chris stmfd sp!, {r0-r3}
695 1.1 chris
696 1.17 thorpej ldr r0, .Lcpufuncs
697 1.14 briggs add lr, pc, #.Lse_cache_purged - . - 8
698 1.6 thorpej ldr pc, [r0, #CF_IDCACHE_WBINV_ALL]
699 1.1 chris
700 1.14 briggs .Lse_cache_purged:
701 1.1 chris ldmfd sp!, {r0-r3}
702 1.1 chris
703 1.1 chris IRQdisable
704 1.1 chris
705 1.1 chris ldr r2, [r1, #(P_ADDR)]
706 1.1 chris ldr r0, [r2, #(PCB_PAGEDIR)]
707 1.1 chris
708 1.1 chris /* Switch the memory to the new process */
709 1.17 thorpej ldr r4, .Lcpufuncs
710 1.14 briggs add lr, pc, #.Lse_context_switched - . - 8
711 1.1 chris ldr pc, [r4, #CF_CONTEXT_SWITCH]
712 1.1 chris
713 1.14 briggs .Lse_context_switched:
714 1.1 chris /* Restore all the save registers */
715 1.1 chris add r7, r2, #PCB_R8
716 1.1 chris ldmia r7, {r8-r13}
717 1.1 chris
718 1.1 chris /* This is not really needed ! */
719 1.1 chris /* Yes it is for the su and fu routines */
720 1.17 thorpej ldr r0, .Lcurpcb
721 1.1 chris str r2, [r0]
722 1.1 chris
723 1.1 chris IRQenable
724 1.1 chris
725 1.1 chris /* str r3, [sp, #-0x0004]!*/
726 1.1 chris
727 1.1 chris /*
728 1.1 chris * Schedule the vmspace and stack to be freed.
729 1.1 chris */
730 1.1 chris mov r0, r3 /* exit2(p) */
731 1.1 chris bl _C_LABEL(exit2)
732 1.1 chris
733 1.1 chris /* Paranoia */
734 1.17 thorpej ldr r1, .Lcurproc
735 1.1 chris mov r0, #0x00000000
736 1.1 chris str r0, [r1]
737 1.1 chris
738 1.17 thorpej ldr r7, .Lwhichqs /* r7 = &whichqs */
739 1.8 thorpej mov r5, #0x00000000 /* r5 = old proc = NULL */
740 1.14 briggs b .Lswitch_search
741 1.1 chris
742 1.7 chris /* LINTSTUB: Func: void savectx(struct pcb *pcb) */
743 1.1 chris ENTRY(savectx)
744 1.1 chris /*
745 1.1 chris * r0 = pcb
746 1.1 chris */
747 1.1 chris
748 1.1 chris /* Push registers.*/
749 1.1 chris stmfd sp!, {r4-r7, lr}
750 1.1 chris
751 1.1 chris /* Store all the registers in the process's pcb */
752 1.1 chris add r2, r0, #(PCB_R8)
753 1.1 chris stmia r2, {r8-r13}
754 1.1 chris
755 1.1 chris /* Pull the regs of the stack */
756 1.1 chris ldmfd sp!, {r4-r7, pc}
757 1.1 chris
758 1.1 chris ENTRY(proc_trampoline)
759 1.19 bjh21 #ifdef MULTIPROCESSOR
760 1.19 bjh21 bl _C_LABEL(proc_trampoline_mp)
761 1.19 bjh21 #endif
762 1.14 briggs add lr, pc, #(.Ltrampoline_return - . - 8)
763 1.1 chris mov r0, r5
764 1.1 chris mov r1, sp
765 1.1 chris mov pc, r4
766 1.1 chris
767 1.14 briggs .Ltrampoline_return:
768 1.1 chris /* Kill irq's */
769 1.13 thorpej mrs r0, cpsr
770 1.1 chris orr r0, r0, #(I32_bit)
771 1.13 thorpej msr cpsr_c, r0
772 1.1 chris
773 1.1 chris PULLFRAME
774 1.1 chris
775 1.1 chris movs pc, lr /* Exit */
776 1.1 chris
777 1.17 thorpej .type .Lcpu_switch_ffs_table, _ASM_TYPE_OBJECT;
778 1.17 thorpej .Lcpu_switch_ffs_table:
779 1.1 chris /* same as ffs table but all nums are -1 from that */
780 1.1 chris /* 0 1 2 3 4 5 6 7 */
781 1.1 chris .byte 0, 0, 1, 12, 2, 6, 0, 13 /* 0- 7 */
782 1.1 chris .byte 3, 0, 7, 0, 0, 0, 0, 14 /* 8-15 */
783 1.1 chris .byte 10, 4, 0, 0, 8, 0, 0, 25 /* 16-23 */
784 1.1 chris .byte 0, 0, 0, 0, 0, 21, 27, 15 /* 24-31 */
785 1.1 chris .byte 31, 11, 5, 0, 0, 0, 0, 0 /* 32-39 */
786 1.1 chris .byte 9, 0, 0, 24, 0, 0, 20, 26 /* 40-47 */
787 1.1 chris .byte 30, 0, 0, 0, 0, 23, 0, 19 /* 48-55 */
788 1.1 chris .byte 29, 0, 22, 18, 28, 17, 16, 0 /* 56-63 */
789 1.1 chris
790 1.1 chris /* End of cpuswitch.S */
791