1 /*-
2 * Copyright (c) 2003 Peter Wemm.
3 * Copyright (c) 1993 The Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 4. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: releng/11.0/sys/amd64/amd64/support.S 303954 2016-08-11 09:30:25Z mjg $
31 */
32
33 #include "opt_ddb.h"
34
35 #include <machine/asmacros.h>
36 #include <machine/pmap.h>
37
38 #include "assym.s"
39
40 .text
41
42 /*
43 * bcopy family
44 * void bzero(void *buf, u_int len)
45 */
46
47 /* done */
48 ENTRY(bzero)
49 PUSH_FRAME_POINTER
50 movq %rsi,%rcx
51 xorl %eax,%eax
52 shrq $3,%rcx
53 cld
54 rep
55 stosq
56 movq %rsi,%rcx
57 andq $7,%rcx
58 rep
59 stosb
60 POP_FRAME_POINTER
61 ret
62 END(bzero)
63
64 /* Address: %rdi */
65 ENTRY(pagezero)
66 PUSH_FRAME_POINTER
67 movq $PAGE_SIZE/8,%rcx
68 xorl %eax,%eax
69 rep
70 stosq
71 POP_FRAME_POINTER
72 ret
73 END(pagezero)
74
75 ENTRY(bcmp)
76 PUSH_FRAME_POINTER
77 movq %rdx,%rcx
78 shrq $3,%rcx
79 cld /* compare forwards */
80 repe
81 cmpsq
82 jne 1f
83
84 movq %rdx,%rcx
85 andq $7,%rcx
86 repe
87 cmpsb
88 1:
89 setne %al
90 movsbl %al,%eax
91 POP_FRAME_POINTER
92 ret
93 END(bcmp)
94
95 /*
96 * bcopy(src, dst, cnt)
97 * rdi, rsi, rdx
98 * ws@tools.de (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
99 */
100 ENTRY(bcopy)
101 PUSH_FRAME_POINTER
102 xchgq %rsi,%rdi
103 movq %rdx,%rcx
104
105 movq %rdi,%rax
106 subq %rsi,%rax
107 cmpq %rcx,%rax /* overlapping && src < dst? */
108 jb 1f
109
110 shrq $3,%rcx /* copy by 64-bit words */
111 cld /* nope, copy forwards */
112 rep
113 movsq
114 movq %rdx,%rcx
115 andq $7,%rcx /* any bytes left? */
116 rep
117 movsb
118 POP_FRAME_POINTER
119 ret
120
121 /* ALIGN_TEXT */
122 1:
123 addq %rcx,%rdi /* copy backwards */
124 addq %rcx,%rsi
125 decq %rdi
126 decq %rsi
127 andq $7,%rcx /* any fractional bytes? */
128 std
129 rep
130 movsb
131 movq %rdx,%rcx /* copy remainder by 32-bit words */
132 shrq $3,%rcx
133 subq $7,%rsi
134 subq $7,%rdi
135 rep
136 movsq
137 cld
138 POP_FRAME_POINTER
139 ret
140 END(bcopy)
141
142 /*
143 * Note: memcpy does not support overlapping copies
144 */
145 ENTRY(memcpy)
146 PUSH_FRAME_POINTER
147 movq %rdi,%rax
148 movq %rdx,%rcx
149 shrq $3,%rcx /* copy by 64-bit words */
150 cld /* copy forwards */
151 rep
152 movsq
153 movq %rdx,%rcx
154 andq $7,%rcx /* any bytes left? */
155 rep
156 movsb
157 POP_FRAME_POINTER
158 ret
159 END(memcpy)
160
161 /*
162 * pagecopy(%rdi=from, %rsi=to)
163 */
164 ENTRY(pagecopy)
165 PUSH_FRAME_POINTER
166 movq $-PAGE_SIZE,%rax
167 movq %rax,%rdx
168 subq %rax,%rdi
169 subq %rax,%rsi
170 1:
171 prefetchnta (%rdi,%rax)
172 addq $64,%rax
173 jne 1b
174 2:
175 movq (%rdi,%rdx),%rax
176 movnti %rax,(%rsi,%rdx)
177 movq 8(%rdi,%rdx),%rax
178 movnti %rax,8(%rsi,%rdx)
179 movq 16(%rdi,%rdx),%rax
180 movnti %rax,16(%rsi,%rdx)
181 movq 24(%rdi,%rdx),%rax
182 movnti %rax,24(%rsi,%rdx)
183 addq $32,%rdx
184 jne 2b
185 sfence
186 POP_FRAME_POINTER
187 ret
188 END(pagecopy)
189
190 /* fillw(pat, base, cnt) */
191 /* %rdi,%rsi, %rdx */
192 ENTRY(fillw)
193 PUSH_FRAME_POINTER
194 movq %rdi,%rax
195 movq %rsi,%rdi
196 movq %rdx,%rcx
197 cld
198 rep
199 stosw
200 POP_FRAME_POINTER
201 ret
202 END(fillw)
203
204 /*****************************************************************************/
205 /* copyout and fubyte family */
206 /*****************************************************************************/
207 /*
208 * Access user memory from inside the kernel. These routines should be
209 * the only places that do this.
210 *
211 * These routines set curpcb->pcb_onfault for the time they execute. When a
212 * protection violation occurs inside the functions, the trap handler
213 * returns to *curpcb->pcb_onfault instead of the function.
214 */
215
216 /*
217 * copyout(from_kernel, to_user, len) - MP SAFE
218 * %rdi, %rsi, %rdx
219 */
220 ENTRY(copyout)
221 PUSH_FRAME_POINTER
222 movq PCPU(CURPCB),%rax
223 movq $copyout_fault,PCB_ONFAULT(%rax)
224 testq %rdx,%rdx /* anything to do? */
225 jz done_copyout
226
227 /*
228 * Check explicitly for non-user addresses. If 486 write protection
229 * is being used, this check is essential because we are in kernel
230 * mode so the h/w does not provide any protection against writing
231 * kernel addresses.
232 */
233
234 /*
235 * First, prevent address wrapping.
236 */
237 movq %rsi,%rax
238 addq %rdx,%rax
239 jc copyout_fault
240 /*
241 * XXX STOP USING VM_MAXUSER_ADDRESS.
242 * It is an end address, not a max, so every time it is used correctly it
243 * looks like there is an off by one error, and of course it caused an off
244 * by one error in several places.
245 */
246 movq $VM_MAXUSER_ADDRESS,%rcx
247 cmpq %rcx,%rax
248 ja copyout_fault
249
250 xchgq %rdi,%rsi
251 /* bcopy(%rsi, %rdi, %rdx) */
252 movq %rdx,%rcx
253
254 shrq $3,%rcx
255 cld
256 rep
257 movsq
258 movb %dl,%cl
259 andb $7,%cl
260 rep
261 movsb
262
263 done_copyout:
264 xorl %eax,%eax
265 movq PCPU(CURPCB),%rdx
266 movq %rax,PCB_ONFAULT(%rdx)
267 POP_FRAME_POINTER
268 ret
269
270 ALIGN_TEXT
271 copyout_fault:
272 movq PCPU(CURPCB),%rdx
273 movq $0,PCB_ONFAULT(%rdx)
274 movq $EFAULT,%rax
275 POP_FRAME_POINTER
276 ret
277 END(copyout)
278
279 /*
280 * copyin(from_user, to_kernel, len) - MP SAFE
281 * %rdi, %rsi, %rdx
282 */
283 ENTRY(copyin)
284 PUSH_FRAME_POINTER
285 movq PCPU(CURPCB),%rax
286 movq $copyin_fault,PCB_ONFAULT(%rax)
287 testq %rdx,%rdx /* anything to do? */
288 jz done_copyin
289
290 /*
291 * make sure address is valid
292 */
293 movq %rdi,%rax
294 addq %rdx,%rax
295 jc copyin_fault
296 movq $VM_MAXUSER_ADDRESS,%rcx
297 cmpq %rcx,%rax
298 ja copyin_fault
299
300 xchgq %rdi,%rsi
301 movq %rdx,%rcx
302 movb %cl,%al
303 shrq $3,%rcx /* copy longword-wise */
304 cld
305 rep
306 movsq
307 movb %al,%cl
308 andb $7,%cl /* copy remaining bytes */
309 rep
310 movsb
311
312 done_copyin:
313 xorl %eax,%eax
314 movq PCPU(CURPCB),%rdx
315 movq %rax,PCB_ONFAULT(%rdx)
316 POP_FRAME_POINTER
317 ret
318
319 ALIGN_TEXT
320 copyin_fault:
321 movq PCPU(CURPCB),%rdx
322 movq $0,PCB_ONFAULT(%rdx)
323 movq $EFAULT,%rax
324 POP_FRAME_POINTER
325 ret
326 END(copyin)
327
328 /*
329 * casueword32. Compare and set user integer. Returns -1 on fault,
330 * 0 if access was successful. Old value is written to *oldp.
331 * dst = %rdi, old = %esi, oldp = %rdx, new = %ecx
332 */
333 ENTRY(casueword32)
334 PUSH_FRAME_POINTER
335 movq PCPU(CURPCB),%r8
336 movq $fusufault,PCB_ONFAULT(%r8)
337
338 movq $VM_MAXUSER_ADDRESS-4,%rax
339 cmpq %rax,%rdi /* verify address is valid */
340 ja fusufault
341
342 movl %esi,%eax /* old */
343 #ifdef SMP
344 lock
345 #endif
346 cmpxchgl %ecx,(%rdi) /* new = %ecx */
347
348 /*
349 * The old value is in %eax. If the store succeeded it will be the
350 * value we expected (old) from before the store, otherwise it will
351 * be the current value. Save %eax into %esi to prepare the return
352 * value.
353 */
354 movl %eax,%esi
355 xorl %eax,%eax
356 movq %rax,PCB_ONFAULT(%r8)
357
358 /*
359 * Access the oldp after the pcb_onfault is cleared, to correctly
360 * catch corrupted pointer.
361 */
362 movl %esi,(%rdx) /* oldp = %rdx */
363 POP_FRAME_POINTER
364 ret
365 END(casueword32)
366
367 /*
368 * casueword. Compare and set user long. Returns -1 on fault,
369 * 0 if access was successful. Old value is written to *oldp.
370 * dst = %rdi, old = %rsi, oldp = %rdx, new = %rcx
371 */
372 ENTRY(casueword)
373 PUSH_FRAME_POINTER
374 movq PCPU(CURPCB),%r8
375 movq $fusufault,PCB_ONFAULT(%r8)
376
377 movq $VM_MAXUSER_ADDRESS-4,%rax
378 cmpq %rax,%rdi /* verify address is valid */
379 ja fusufault
380
381 movq %rsi,%rax /* old */
382 #ifdef SMP
383 lock
384 #endif
385 cmpxchgq %rcx,(%rdi) /* new = %rcx */
386
387 /*
388 * The old value is in %rax. If the store succeeded it will be the
389 * value we expected (old) from before the store, otherwise it will
390 * be the current value.
391 */
392 movq %rax,%rsi
393 xorl %eax,%eax
394 movq %rax,PCB_ONFAULT(%r8)
395 movq %rsi,(%rdx)
396 POP_FRAME_POINTER
397 ret
398 END(casueword)
399
400 /*
401 * Fetch (load) a 64-bit word, a 32-bit word, a 16-bit word, or an 8-bit
402 * byte from user memory.
403 * addr = %rdi, valp = %rsi
404 */
405
406 ALTENTRY(fueword64)
407 ENTRY(fueword)
408 PUSH_FRAME_POINTER
409 movq PCPU(CURPCB),%rcx
410 movq $fusufault,PCB_ONFAULT(%rcx)
411
412 movq $VM_MAXUSER_ADDRESS-8,%rax
413 cmpq %rax,%rdi /* verify address is valid */
414 ja fusufault
415
416 xorl %eax,%eax
417 movq (%rdi),%r11
418 movq %rax,PCB_ONFAULT(%rcx)
419 movq %r11,(%rsi)
420 POP_FRAME_POINTER
421 ret
422 END(fueword64)
423 END(fueword)
424
425 ENTRY(fueword32)
426 PUSH_FRAME_POINTER
427 movq PCPU(CURPCB),%rcx
428 movq $fusufault,PCB_ONFAULT(%rcx)
429
430 movq $VM_MAXUSER_ADDRESS-4,%rax
431 cmpq %rax,%rdi /* verify address is valid */
432 ja fusufault
433
434 xorl %eax,%eax
435 movl (%rdi),%r11d
436 movq %rax,PCB_ONFAULT(%rcx)
437 movl %r11d,(%rsi)
438 POP_FRAME_POINTER
439 ret
440 END(fueword32)
441
442 /*
443 * fuswintr() and suswintr() are specialized variants of fuword16() and
444 * suword16(), respectively. They are called from the profiling code,
445 * potentially at interrupt time. If they fail, that's okay; good things
446 * will happen later. They always fail for now, until the trap code is
447 * able to deal with this.
448 */
449 ALTENTRY(suswintr)
450 ENTRY(fuswintr)
451 movq $-1,%rax
452 ret
453 END(suswintr)
454 END(fuswintr)
455
456 ENTRY(fuword16)
457 PUSH_FRAME_POINTER
458 movq PCPU(CURPCB),%rcx
459 movq $fusufault,PCB_ONFAULT(%rcx)
460
461 movq $VM_MAXUSER_ADDRESS-2,%rax
462 cmpq %rax,%rdi
463 ja fusufault
464
465 movzwl (%rdi),%eax
466 movq $0,PCB_ONFAULT(%rcx)
467 POP_FRAME_POINTER
468 ret
469 END(fuword16)
470
471 ENTRY(fubyte)
472 PUSH_FRAME_POINTER
473 movq PCPU(CURPCB),%rcx
474 movq $fusufault,PCB_ONFAULT(%rcx)
475
476 movq $VM_MAXUSER_ADDRESS-1,%rax
477 cmpq %rax,%rdi
478 ja fusufault
479
480 movzbl (%rdi),%eax
481 movq $0,PCB_ONFAULT(%rcx)
482 POP_FRAME_POINTER
483 ret
484 END(fubyte)
485
486 ALIGN_TEXT
487 fusufault:
488 movq PCPU(CURPCB),%rcx
489 xorl %eax,%eax
490 movq %rax,PCB_ONFAULT(%rcx)
491 decq %rax
492 POP_FRAME_POINTER
493 ret
494
495 /*
496 * Store a 64-bit word, a 32-bit word, a 16-bit word, or an 8-bit byte to
497 * user memory. All these functions are MPSAFE.
498 * addr = %rdi, value = %rsi
499 */
500 ALTENTRY(suword64)
501 ENTRY(suword)
502 PUSH_FRAME_POINTER
503 movq PCPU(CURPCB),%rcx
504 movq $fusufault,PCB_ONFAULT(%rcx)
505
506 movq $VM_MAXUSER_ADDRESS-8,%rax
507 cmpq %rax,%rdi /* verify address validity */
508 ja fusufault
509
510 movq %rsi,(%rdi)
511 xorl %eax,%eax
512 movq PCPU(CURPCB),%rcx
513 movq %rax,PCB_ONFAULT(%rcx)
514 POP_FRAME_POINTER
515 ret
516 END(suword64)
517 END(suword)
518
519 ENTRY(suword32)
520 PUSH_FRAME_POINTER
521 movq PCPU(CURPCB),%rcx
522 movq $fusufault,PCB_ONFAULT(%rcx)
523
524 movq $VM_MAXUSER_ADDRESS-4,%rax
525 cmpq %rax,%rdi /* verify address validity */
526 ja fusufault
527
528 movl %esi,(%rdi)
529 xorl %eax,%eax
530 movq PCPU(CURPCB),%rcx
531 movq %rax,PCB_ONFAULT(%rcx)
532 POP_FRAME_POINTER
533 ret
534 END(suword32)
535
536 ENTRY(suword16)
537 PUSH_FRAME_POINTER
538 movq PCPU(CURPCB),%rcx
539 movq $fusufault,PCB_ONFAULT(%rcx)
540
541 movq $VM_MAXUSER_ADDRESS-2,%rax
542 cmpq %rax,%rdi /* verify address validity */
543 ja fusufault
544
545 movw %si,(%rdi)
546 xorl %eax,%eax
547 movq PCPU(CURPCB),%rcx /* restore trashed register */
548 movq %rax,PCB_ONFAULT(%rcx)
549 POP_FRAME_POINTER
550 ret
551 END(suword16)
552
553 ENTRY(subyte)
554 PUSH_FRAME_POINTER
555 movq PCPU(CURPCB),%rcx
556 movq $fusufault,PCB_ONFAULT(%rcx)
557
558 movq $VM_MAXUSER_ADDRESS-1,%rax
559 cmpq %rax,%rdi /* verify address validity */
560 ja fusufault
561
562 movl %esi,%eax
563 movb %al,(%rdi)
564 xorl %eax,%eax
565 movq PCPU(CURPCB),%rcx /* restore trashed register */
566 movq %rax,PCB_ONFAULT(%rcx)
567 POP_FRAME_POINTER
568 ret
569 END(subyte)
570
571 /*
572 * copyinstr(from, to, maxlen, int *lencopied) - MP SAFE
573 * %rdi, %rsi, %rdx, %rcx
574 *
575 * copy a string from from to to, stop when a 0 character is reached.
576 * return ENAMETOOLONG if string is longer than maxlen, and
577 * EFAULT on protection violations. If lencopied is non-zero,
578 * return the actual length in *lencopied.
579 */
580 ENTRY(copyinstr)
581 PUSH_FRAME_POINTER
582 movq %rdx,%r8 /* %r8 = maxlen */
583 movq %rcx,%r9 /* %r9 = *len */
584 xchgq %rdi,%rsi /* %rdi = from, %rsi = to */
585 movq PCPU(CURPCB),%rcx
586 movq $cpystrflt,PCB_ONFAULT(%rcx)
587
588 movq $VM_MAXUSER_ADDRESS,%rax
589
590 /* make sure 'from' is within bounds */
591 subq %rsi,%rax
592 jbe cpystrflt
593
594 /* restrict maxlen to <= VM_MAXUSER_ADDRESS-from */
595 cmpq %rdx,%rax
596 jae 1f
597 movq %rax,%rdx
598 movq %rax,%r8
599 1:
600 incq %rdx
601 cld
602
603 2:
604 decq %rdx
605 jz 3f
606
607 lodsb
608 stosb
609 orb %al,%al
610 jnz 2b
611
612 /* Success -- 0 byte reached */
613 decq %rdx
614 xorl %eax,%eax
615 jmp cpystrflt_x
616 3:
617 /* rdx is zero - return ENAMETOOLONG or EFAULT */
618 movq $VM_MAXUSER_ADDRESS,%rax
619 cmpq %rax,%rsi
620 jae cpystrflt
621 4:
622 movq $ENAMETOOLONG,%rax
623 jmp cpystrflt_x
624
625 cpystrflt:
626 movq $EFAULT,%rax
627
628 cpystrflt_x:
629 /* set *lencopied and return %eax */
630 movq PCPU(CURPCB),%rcx
631 movq $0,PCB_ONFAULT(%rcx)
632
633 testq %r9,%r9
634 jz 1f
635 subq %rdx,%r8
636 movq %r8,(%r9)
637 1:
638 POP_FRAME_POINTER
639 ret
640 END(copyinstr)
641
642 /*
643 * copystr(from, to, maxlen, int *lencopied) - MP SAFE
644 * %rdi, %rsi, %rdx, %rcx
645 */
646 ENTRY(copystr)
647 PUSH_FRAME_POINTER
648 movq %rdx,%r8 /* %r8 = maxlen */
649
650 xchgq %rdi,%rsi
651 incq %rdx
652 cld
653 1:
654 decq %rdx
655 jz 4f
656 lodsb
657 stosb
658 orb %al,%al
659 jnz 1b
660
661 /* Success -- 0 byte reached */
662 decq %rdx
663 xorl %eax,%eax
664 jmp 6f
665 4:
666 /* rdx is zero -- return ENAMETOOLONG */
667 movq $ENAMETOOLONG,%rax
668
669 6:
670
671 testq %rcx,%rcx
672 jz 7f
673 /* set *lencopied and return %rax */
674 subq %rdx,%r8
675 movq %r8,(%rcx)
676 7:
677 POP_FRAME_POINTER
678 ret
679 END(copystr)
680
681 /*
682 * Handling of special amd64 registers and descriptor tables etc
683 * %rdi
684 */
685 /* void lgdt(struct region_descriptor *rdp); */
686 ENTRY(lgdt)
687 /* reload the descriptor table */
688 lgdt (%rdi)
689
690 /* flush the prefetch q */
691 jmp 1f
692 nop
693 1:
694 movl $KDSEL,%eax
695 movl %eax,%ds
696 movl %eax,%es
697 movl %eax,%fs /* Beware, use wrmsr to set 64 bit base */
698 movl %eax,%gs
699 movl %eax,%ss
700
701 /* reload code selector by turning return into intersegmental return */
702 popq %rax
703 pushq $KCSEL
704 pushq %rax
705 MEXITCOUNT
706 lretq
707 END(lgdt)
708
709 /*****************************************************************************/
710 /* setjump, longjump */
711 /*****************************************************************************/
712
713 ENTRY(setjmp)
714 movq %rbx,0(%rdi) /* save rbx */
715 movq %rsp,8(%rdi) /* save rsp */
716 movq %rbp,16(%rdi) /* save rbp */
717 movq %r12,24(%rdi) /* save r12 */
718 movq %r13,32(%rdi) /* save r13 */
719 movq %r14,40(%rdi) /* save r14 */
720 movq %r15,48(%rdi) /* save r15 */
721 movq 0(%rsp),%rdx /* get rta */
722 movq %rdx,56(%rdi) /* save rip */
723 xorl %eax,%eax /* return(0); */
724 ret
725 END(setjmp)
726
727 ENTRY(longjmp)
728 movq 0(%rdi),%rbx /* restore rbx */
729 movq 8(%rdi),%rsp /* restore rsp */
730 movq 16(%rdi),%rbp /* restore rbp */
731 movq 24(%rdi),%r12 /* restore r12 */
732 movq 32(%rdi),%r13 /* restore r13 */
733 movq 40(%rdi),%r14 /* restore r14 */
734 movq 48(%rdi),%r15 /* restore r15 */
735 movq 56(%rdi),%rdx /* get rta */
736 movq %rdx,0(%rsp) /* put in return frame */
737 xorl %eax,%eax /* return(1); */
738 incl %eax
739 ret
740 END(longjmp)
741
742 /*
743 * Support for reading MSRs in the safe manner.
744 */
745 ENTRY(rdmsr_safe)
746 /* int rdmsr_safe(u_int msr, uint64_t *data) */
747 PUSH_FRAME_POINTER
748 movq PCPU(CURPCB),%r8
749 movq $msr_onfault,PCB_ONFAULT(%r8)
750 movl %edi,%ecx
751 rdmsr /* Read MSR pointed by %ecx. Returns
752 hi byte in edx, lo in %eax */
753 salq $32,%rdx /* sign-shift %rdx left */
754 movl %eax,%eax /* zero-extend %eax -> %rax */
755 orq %rdx,%rax
756 movq %rax,(%rsi)
757 xorq %rax,%rax
758 movq %rax,PCB_ONFAULT(%r8)
759 POP_FRAME_POINTER
760 ret
761
762 /*
763 * Support for writing MSRs in the safe manner.
764 */
765 ENTRY(wrmsr_safe)
766 /* int wrmsr_safe(u_int msr, uint64_t data) */
767 PUSH_FRAME_POINTER
768 movq PCPU(CURPCB),%r8
769 movq $msr_onfault,PCB_ONFAULT(%r8)
770 movl %edi,%ecx
771 movl %esi,%eax
772 sarq $32,%rsi
773 movl %esi,%edx
774 wrmsr /* Write MSR pointed by %ecx. Accepts
775 hi byte in edx, lo in %eax. */
776 xorq %rax,%rax
777 movq %rax,PCB_ONFAULT(%r8)
778 POP_FRAME_POINTER
779 ret
780
781 /*
782 * MSR operations fault handler
783 */
784 ALIGN_TEXT
785 msr_onfault:
786 movq $0,PCB_ONFAULT(%r8)
787 movl $EFAULT,%eax
788 POP_FRAME_POINTER
789 ret
Cache object: 6a72863969e7490cf75b6cd271287fa7
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