FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/swtch.s
1 /*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * William Jolitz.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: releng/10.3/sys/i386/i386/swtch.s 282065 2015-04-27 08:02:12Z kib $
33 */
34
35 #include "opt_npx.h"
36 #include "opt_sched.h"
37
38 #include <machine/asmacros.h>
39
40 #include "assym.s"
41
42 #if defined(SMP) && defined(SCHED_ULE)
43 #define SETOP xchgl
44 #define BLOCK_SPIN(reg) \
45 movl $blocked_lock,%eax ; \
46 100: ; \
47 lock ; \
48 cmpxchgl %eax,TD_LOCK(reg) ; \
49 jne 101f ; \
50 pause ; \
51 jmp 100b ; \
52 101:
53 #else
54 #define SETOP movl
55 #define BLOCK_SPIN(reg)
56 #endif
57
58 /*****************************************************************************/
59 /* Scheduling */
60 /*****************************************************************************/
61
62 .text
63
64 /*
65 * cpu_throw()
66 *
67 * This is the second half of cpu_switch(). It is used when the current
68 * thread is either a dummy or slated to die, and we no longer care
69 * about its state. This is only a slight optimization and is probably
70 * not worth it anymore. Note that we need to clear the pm_active bits so
71 * we do need the old proc if it still exists.
72 * 0(%esp) = ret
73 * 4(%esp) = oldtd
74 * 8(%esp) = newtd
75 */
76 ENTRY(cpu_throw)
77 movl PCPU(CPUID), %esi
78 movl 4(%esp),%ecx /* Old thread */
79 testl %ecx,%ecx /* no thread? */
80 jz 1f
81 /* release bit from old pm_active */
82 movl PCPU(CURPMAP), %ebx
83 #ifdef SMP
84 lock
85 #endif
86 btrl %esi, PM_ACTIVE(%ebx) /* clear old */
87 1:
88 movl 8(%esp),%ecx /* New thread */
89 movl TD_PCB(%ecx),%edx
90 movl PCB_CR3(%edx),%eax
91 LOAD_CR3(%eax)
92 /* set bit in new pm_active */
93 movl TD_PROC(%ecx),%eax
94 movl P_VMSPACE(%eax), %ebx
95 addl $VM_PMAP, %ebx
96 movl %ebx, PCPU(CURPMAP)
97 #ifdef SMP
98 lock
99 #endif
100 btsl %esi, PM_ACTIVE(%ebx) /* set new */
101 jmp sw1
102 END(cpu_throw)
103
104 /*
105 * cpu_switch(old, new)
106 *
107 * Save the current thread state, then select the next thread to run
108 * and load its state.
109 * 0(%esp) = ret
110 * 4(%esp) = oldtd
111 * 8(%esp) = newtd
112 * 12(%esp) = newlock
113 */
114 ENTRY(cpu_switch)
115
116 /* Switch to new thread. First, save context. */
117 movl 4(%esp),%ecx
118
119 #ifdef INVARIANTS
120 testl %ecx,%ecx /* no thread? */
121 jz badsw2 /* no, panic */
122 #endif
123
124 movl TD_PCB(%ecx),%edx
125
126 movl (%esp),%eax /* Hardware registers */
127 movl %eax,PCB_EIP(%edx)
128 movl %ebx,PCB_EBX(%edx)
129 movl %esp,PCB_ESP(%edx)
130 movl %ebp,PCB_EBP(%edx)
131 movl %esi,PCB_ESI(%edx)
132 movl %edi,PCB_EDI(%edx)
133 mov %gs,PCB_GS(%edx)
134 pushfl /* PSL */
135 popl PCB_PSL(%edx)
136 /* Test if debug registers should be saved. */
137 testl $PCB_DBREGS,PCB_FLAGS(%edx)
138 jz 1f /* no, skip over */
139 movl %dr7,%eax /* yes, do the save */
140 movl %eax,PCB_DR7(%edx)
141 andl $0x0000fc00, %eax /* disable all watchpoints */
142 movl %eax,%dr7
143 movl %dr6,%eax
144 movl %eax,PCB_DR6(%edx)
145 movl %dr3,%eax
146 movl %eax,PCB_DR3(%edx)
147 movl %dr2,%eax
148 movl %eax,PCB_DR2(%edx)
149 movl %dr1,%eax
150 movl %eax,PCB_DR1(%edx)
151 movl %dr0,%eax
152 movl %eax,PCB_DR0(%edx)
153 1:
154
155 #ifdef DEV_NPX
156 /* have we used fp, and need a save? */
157 cmpl %ecx,PCPU(FPCURTHREAD)
158 jne 1f
159 pushl PCB_SAVEFPU(%edx) /* h/w bugs make saving complicated */
160 call npxsave /* do it in a big C function */
161 popl %eax
162 1:
163 #endif
164
165 /* Save is done. Now fire up new thread. Leave old vmspace. */
166 movl 4(%esp),%edi
167 movl 8(%esp),%ecx /* New thread */
168 movl 12(%esp),%esi /* New lock */
169 #ifdef INVARIANTS
170 testl %ecx,%ecx /* no thread? */
171 jz badsw3 /* no, panic */
172 #endif
173 movl TD_PCB(%ecx),%edx
174
175 /* switch address space */
176 movl PCB_CR3(%edx),%eax
177 #if defined(PAE) || defined(PAE_TABLES)
178 cmpl %eax,IdlePDPT /* Kernel address space? */
179 #else
180 cmpl %eax,IdlePTD /* Kernel address space? */
181 #endif
182 je sw0
183 READ_CR3(%ebx) /* The same address space? */
184 cmpl %ebx,%eax
185 je sw0
186 LOAD_CR3(%eax) /* new address space */
187 movl %esi,%eax
188 movl PCPU(CPUID),%esi
189 SETOP %eax,TD_LOCK(%edi) /* Switchout td_lock */
190
191 /* Release bit from old pmap->pm_active */
192 movl PCPU(CURPMAP), %ebx
193 #ifdef SMP
194 lock
195 #endif
196 btrl %esi, PM_ACTIVE(%ebx) /* clear old */
197
198 /* Set bit in new pmap->pm_active */
199 movl TD_PROC(%ecx),%eax /* newproc */
200 movl P_VMSPACE(%eax), %ebx
201 addl $VM_PMAP, %ebx
202 movl %ebx, PCPU(CURPMAP)
203 #ifdef SMP
204 lock
205 #endif
206 btsl %esi, PM_ACTIVE(%ebx) /* set new */
207 jmp sw1
208
209 sw0:
210 SETOP %esi,TD_LOCK(%edi) /* Switchout td_lock */
211 sw1:
212 BLOCK_SPIN(%ecx)
213 #ifdef XEN
214 pushl %eax
215 pushl %ecx
216 pushl %edx
217 call xen_handle_thread_switch
218 popl %edx
219 popl %ecx
220 popl %eax
221 /*
222 * XXX set IOPL
223 */
224 #else
225 /*
226 * At this point, we've switched address spaces and are ready
227 * to load up the rest of the next context.
228 */
229 cmpl $0, PCB_EXT(%edx) /* has pcb extension? */
230 je 1f /* If not, use the default */
231 movl $1, PCPU(PRIVATE_TSS) /* mark use of private tss */
232 movl PCB_EXT(%edx), %edi /* new tss descriptor */
233 jmp 2f /* Load it up */
234
235 1: /*
236 * Use the common default TSS instead of our own.
237 * Set our stack pointer into the TSS, it's set to just
238 * below the PCB. In C, common_tss.tss_esp0 = &pcb - 16;
239 */
240 leal -16(%edx), %ebx /* leave space for vm86 */
241 movl %ebx, PCPU(COMMON_TSS) + TSS_ESP0
242
243 /*
244 * Test this CPU's bit in the bitmap to see if this
245 * CPU was using a private TSS.
246 */
247 cmpl $0, PCPU(PRIVATE_TSS) /* Already using the common? */
248 je 3f /* if so, skip reloading */
249 movl $0, PCPU(PRIVATE_TSS)
250 PCPU_ADDR(COMMON_TSSD, %edi)
251 2:
252 /* Move correct tss descriptor into GDT slot, then reload tr. */
253 movl PCPU(TSS_GDT), %ebx /* entry in GDT */
254 movl 0(%edi), %eax
255 movl 4(%edi), %esi
256 movl %eax, 0(%ebx)
257 movl %esi, 4(%ebx)
258 movl $GPROC0_SEL*8, %esi /* GSEL(GPROC0_SEL, SEL_KPL) */
259 ltr %si
260 3:
261
262 /* Copy the %fs and %gs selectors into this pcpu gdt */
263 leal PCB_FSD(%edx), %esi
264 movl PCPU(FSGS_GDT), %edi
265 movl 0(%esi), %eax /* %fs selector */
266 movl 4(%esi), %ebx
267 movl %eax, 0(%edi)
268 movl %ebx, 4(%edi)
269 movl 8(%esi), %eax /* %gs selector, comes straight after */
270 movl 12(%esi), %ebx
271 movl %eax, 8(%edi)
272 movl %ebx, 12(%edi)
273 #endif
274 /* Restore context. */
275 movl PCB_EBX(%edx),%ebx
276 movl PCB_ESP(%edx),%esp
277 movl PCB_EBP(%edx),%ebp
278 movl PCB_ESI(%edx),%esi
279 movl PCB_EDI(%edx),%edi
280 movl PCB_EIP(%edx),%eax
281 movl %eax,(%esp)
282 pushl PCB_PSL(%edx)
283 popfl
284
285 movl %edx, PCPU(CURPCB)
286 movl TD_TID(%ecx),%eax
287 movl %ecx, PCPU(CURTHREAD) /* into next thread */
288
289 /*
290 * Determine the LDT to use and load it if is the default one and
291 * that is not the current one.
292 */
293 movl TD_PROC(%ecx),%eax
294 cmpl $0,P_MD+MD_LDT(%eax)
295 jnz 1f
296 movl _default_ldt,%eax
297 cmpl PCPU(CURRENTLDT),%eax
298 je 2f
299 LLDT(_default_ldt)
300 movl %eax,PCPU(CURRENTLDT)
301 jmp 2f
302 1:
303 /* Load the LDT when it is not the default one. */
304 pushl %edx /* Preserve pointer to pcb. */
305 addl $P_MD,%eax /* Pointer to mdproc is arg. */
306 pushl %eax
307 call set_user_ldt
308 addl $4,%esp
309 popl %edx
310 2:
311
312 /* This must be done after loading the user LDT. */
313 .globl cpu_switch_load_gs
314 cpu_switch_load_gs:
315 mov PCB_GS(%edx),%gs
316
317 /* Test if debug registers should be restored. */
318 testl $PCB_DBREGS,PCB_FLAGS(%edx)
319 jz 1f
320
321 /*
322 * Restore debug registers. The special code for dr7 is to
323 * preserve the current values of its reserved bits.
324 */
325 movl PCB_DR6(%edx),%eax
326 movl %eax,%dr6
327 movl PCB_DR3(%edx),%eax
328 movl %eax,%dr3
329 movl PCB_DR2(%edx),%eax
330 movl %eax,%dr2
331 movl PCB_DR1(%edx),%eax
332 movl %eax,%dr1
333 movl PCB_DR0(%edx),%eax
334 movl %eax,%dr0
335 movl %dr7,%eax
336 andl $0x0000fc00,%eax
337 movl PCB_DR7(%edx),%ecx
338 andl $~0x0000fc00,%ecx
339 orl %ecx,%eax
340 movl %eax,%dr7
341 1:
342 ret
343
344 #ifdef INVARIANTS
345 badsw1:
346 pushal
347 pushl $sw0_1
348 call panic
349 sw0_1: .asciz "cpu_throw: no newthread supplied"
350
351 badsw2:
352 pushal
353 pushl $sw0_2
354 call panic
355 sw0_2: .asciz "cpu_switch: no curthread supplied"
356
357 badsw3:
358 pushal
359 pushl $sw0_3
360 call panic
361 sw0_3: .asciz "cpu_switch: no newthread supplied"
362 #endif
363 END(cpu_switch)
364
365 /*
366 * savectx(pcb)
367 * Update pcb, saving current processor state.
368 */
369 ENTRY(savectx)
370 /* Fetch PCB. */
371 movl 4(%esp),%ecx
372
373 /* Save caller's return address. Child won't execute this routine. */
374 movl (%esp),%eax
375 movl %eax,PCB_EIP(%ecx)
376
377 movl %cr3,%eax
378 movl %eax,PCB_CR3(%ecx)
379
380 movl %ebx,PCB_EBX(%ecx)
381 movl %esp,PCB_ESP(%ecx)
382 movl %ebp,PCB_EBP(%ecx)
383 movl %esi,PCB_ESI(%ecx)
384 movl %edi,PCB_EDI(%ecx)
385 mov %gs,PCB_GS(%ecx)
386 pushfl
387 popl PCB_PSL(%ecx)
388
389 movl %cr0,%eax
390 movl %eax,PCB_CR0(%ecx)
391 movl %cr2,%eax
392 movl %eax,PCB_CR2(%ecx)
393 movl %cr4,%eax
394 movl %eax,PCB_CR4(%ecx)
395
396 movl %dr0,%eax
397 movl %eax,PCB_DR0(%ecx)
398 movl %dr1,%eax
399 movl %eax,PCB_DR1(%ecx)
400 movl %dr2,%eax
401 movl %eax,PCB_DR2(%ecx)
402 movl %dr3,%eax
403 movl %eax,PCB_DR3(%ecx)
404 movl %dr6,%eax
405 movl %eax,PCB_DR6(%ecx)
406 movl %dr7,%eax
407 movl %eax,PCB_DR7(%ecx)
408
409 mov %ds,PCB_DS(%ecx)
410 mov %es,PCB_ES(%ecx)
411 mov %fs,PCB_FS(%ecx)
412 mov %ss,PCB_SS(%ecx)
413
414 sgdt PCB_GDT(%ecx)
415 sidt PCB_IDT(%ecx)
416 sldt PCB_LDT(%ecx)
417 str PCB_TR(%ecx)
418
419 movl $1,%eax
420 ret
421 END(savectx)
422
423 /*
424 * resumectx(pcb) __fastcall
425 * Resuming processor state from pcb.
426 */
427 ENTRY(resumectx)
428 /* Restore GDT. */
429 lgdt PCB_GDT(%ecx)
430
431 /* Restore segment registers */
432 movzwl PCB_DS(%ecx),%eax
433 mov %ax,%ds
434 movzwl PCB_ES(%ecx),%eax
435 mov %ax,%es
436 movzwl PCB_FS(%ecx),%eax
437 mov %ax,%fs
438 movzwl PCB_GS(%ecx),%eax
439 movw %ax,%gs
440 movzwl PCB_SS(%ecx),%eax
441 mov %ax,%ss
442
443 /* Restore CR2, CR4, CR3 and CR0 */
444 movl PCB_CR2(%ecx),%eax
445 movl %eax,%cr2
446 movl PCB_CR4(%ecx),%eax
447 movl %eax,%cr4
448 movl PCB_CR3(%ecx),%eax
449 movl %eax,%cr3
450 movl PCB_CR0(%ecx),%eax
451 movl %eax,%cr0
452 jmp 1f
453 1:
454
455 /* Restore descriptor tables */
456 lidt PCB_IDT(%ecx)
457 lldt PCB_LDT(%ecx)
458
459 #define SDT_SYS386TSS 9
460 #define SDT_SYS386BSY 11
461 /* Clear "task busy" bit and reload TR */
462 movl PCPU(TSS_GDT),%eax
463 andb $(~SDT_SYS386BSY | SDT_SYS386TSS),5(%eax)
464 movzwl PCB_TR(%ecx),%eax
465 ltr %ax
466 #undef SDT_SYS386TSS
467 #undef SDT_SYS386BSY
468
469 /* Restore debug registers */
470 movl PCB_DR0(%ecx),%eax
471 movl %eax,%dr0
472 movl PCB_DR1(%ecx),%eax
473 movl %eax,%dr1
474 movl PCB_DR2(%ecx),%eax
475 movl %eax,%dr2
476 movl PCB_DR3(%ecx),%eax
477 movl %eax,%dr3
478 movl PCB_DR6(%ecx),%eax
479 movl %eax,%dr6
480 movl PCB_DR7(%ecx),%eax
481 movl %eax,%dr7
482
483 /* Restore other registers */
484 movl PCB_EDI(%ecx),%edi
485 movl PCB_ESI(%ecx),%esi
486 movl PCB_EBP(%ecx),%ebp
487 movl PCB_ESP(%ecx),%esp
488 movl PCB_EBX(%ecx),%ebx
489
490 /* reload code selector by turning return into intersegmental return */
491 pushl PCB_EIP(%ecx)
492 movl $KCSEL,4(%esp)
493 xorl %eax,%eax
494 lret
495 END(resumectx)
Cache object: fc2fa7892bc541f16c9bed37d95f2e7c
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