2 * Copyright (c) 2003-2011 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * pmap invalidation support code. Certain hardware requirements must
37 * be dealt with when manipulating page table entries and page directory
38 * entries within a pmap. In particular, we cannot safely manipulate
39 * page tables which are in active use by another cpu (even if it is
40 * running in userland) for two reasons: First, TLB writebacks will
41 * race against our own modifications and tests. Second, even if we
42 * were to use bus-locked instruction we can still screw up the
43 * target cpu's instruction pipeline due to Intel cpu errata.
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
50 #include <sys/vmmeter.h>
51 #include <sys/thread2.h>
52 #include <sys/sysctl.h>
56 #include <vm/vm_object.h>
58 #include <machine/cputypes.h>
59 #include <machine/md_var.h>
60 #include <machine/specialreg.h>
61 #include <machine/smp.h>
62 #include <machine/globaldata.h>
63 #include <machine/pmap.h>
64 #include <machine/pmap_inval.h>
65 #include <machine/clock.h>
68 #define LOOPRECOVER /* enable watchdog */
72 * Watchdog recovery interval = 1.0 / (1 << radix), or 1/16 second
73 * for the initial watchdog. If the initial watchdog fails, further
74 * instances occur at 1/2 second intervals.
76 * The watchdog value is generous for two reasons. First, because the
77 * situaation is not supposed to happen at all (but does), and second,
78 * because VMs could be very slow at handling IPIs.
80 #define LOOPRECOVER_RADIX1 4 /* initial recovery */
81 #define LOOPRECOVER_RADIX2 1 /* repeated recoveries */
83 #define MAX_INVAL_PAGES 128
85 struct pmap_inval_info {
90 enum { INVDONE, INVSTORE, INVCMPSET } mode;
102 typedef struct pmap_inval_info pmap_inval_info_t;
104 static pmap_inval_info_t invinfo[MAXCPU];
105 extern cpumask_t smp_invmask;
108 extern cpumask_t smp_in_mask;
110 extern cpumask_t smp_smurf_mask;
112 static long pmap_inval_bulk_count;
114 SYSCTL_LONG(_machdep, OID_AUTO, pmap_inval_bulk_count, CTLFLAG_RW,
115 &pmap_inval_bulk_count, 0, "");
118 pmap_inval_init(pmap_t pmap)
123 crit_enter_id("inval");
125 if (pmap != &kernel_pmap) {
127 olock = pmap->pm_active_lock;
129 nlock = olock | CPULOCK_EXCL;
130 if (olock != nlock &&
131 atomic_cmpset_int(&pmap->pm_active_lock,
138 atomic_add_acq_long(&pmap->pm_invgen, 1);
143 pmap_inval_done(pmap_t pmap)
145 if (pmap != &kernel_pmap) {
146 atomic_clear_int(&pmap->pm_active_lock, CPULOCK_EXCL);
147 atomic_add_acq_long(&pmap->pm_invgen, 1);
149 crit_exit_id("inval");
155 * Debugging and lost IPI recovery code.
160 loopwdog(struct pmap_inval_info *info)
165 if (info->tsc_target - tsc < 0 && tsc_frequency) {
166 info->tsc_target = tsc + (tsc_frequency >> LOOPRECOVER_RADIX2);
174 loopdebug(const char *msg, pmap_inval_info_t *info)
177 int cpu = mycpu->gd_cpuid;
181 atomic_add_long(&smp_smurf_mask.ary[0], 0);
183 kprintf("ipilost-%s! %d mode=%d m=%08jx d=%08jx "
193 , msg, cpu, info->mode,
197 , info->sigmask.ary[0]
203 , smp_smurf_mask.ary[0]
207 for (p = 0; p < ncpus; ++p)
208 kprintf(" %d", CPU_prvspace[p]->mdglobaldata.gd_xinvaltlb);
216 #define CHECKSIGMASK(info) _checksigmask(info, __FILE__, __LINE__)
220 _checksigmask(pmap_inval_info_t *info, const char *file, int line)
225 CPUMASK_ANDMASK(tmp, info->sigmask);
226 if (CPUMASK_CMPMASKNEQ(tmp, info->mask)) {
227 kprintf("\"%s\" line %d: bad sig/mask %08jx %08jx\n",
228 file, line, info->sigmask.ary[0], info->mask.ary[0]);
234 #define CHECKSIGMASK(info)
239 * Invalidate the specified va across all cpus associated with the pmap.
240 * If va == (vm_offset_t)-1, we invltlb() instead of invlpg(). The operation
241 * will be done fully synchronously with storing npte into *ptep and returning
244 * If ptep is NULL the operation will execute semi-synchronously.
245 * ptep must be NULL if npgs > 1
248 pmap_inval_smp(pmap_t pmap, vm_offset_t va, int npgs,
249 pt_entry_t *ptep, pt_entry_t npte)
251 globaldata_t gd = mycpu;
252 pmap_inval_info_t *info;
254 int cpu = gd->gd_cpuid;
256 unsigned long rflags;
259 * Initialize invalidation for pmap and enter critical section.
263 pmap_inval_init(pmap);
266 * Shortcut single-cpu case if possible.
268 if (CPUMASK_CMPMASKEQ(pmap->pm_active, gd->gd_cpumask)) {
270 * Convert to invltlb if there are too many pages to
273 if (npgs > MAX_INVAL_PAGES) {
275 va = (vm_offset_t)-1;
279 * Invalidate the specified pages, handle invltlb if requested.
284 opte = atomic_swap_long(ptep, npte);
287 if (va == (vm_offset_t)-1)
289 cpu_invlpg((void *)va);
292 if (va == (vm_offset_t)-1)
294 pmap_inval_done(pmap);
300 * We need a critical section to prevent getting preempted while
301 * we setup our command. A preemption might execute its own
302 * pmap_inval*() command and create confusion below.
304 * tsc_target is our watchdog timeout that will attempt to recover
305 * from a lost IPI. Set to 1/16 second for now.
307 info = &invinfo[cpu];
308 info->tsc_target = rdtsc() + (tsc_frequency >> LOOPRECOVER_RADIX1);
311 * We must wait for other cpus which may still be finishing up a
312 * prior operation that we requested.
314 * We do not have to disable interrupts here. An Xinvltlb can occur
315 * at any time (even within a critical section), but it will not
316 * act on our command until we set our done bits.
318 while (CPUMASK_TESTNZERO(info->done)) {
320 if (loopwdog(info)) {
322 loopdebug("A", info);
323 /* XXX recover from possible bug */
324 CPUMASK_ASSZERO(info->done);
329 KKASSERT(info->mode == INVDONE);
332 * Must set our cpu in the invalidation scan mask before
333 * any possibility of [partial] execution (remember, XINVLTLB
334 * can interrupt a critical section).
336 ATOMIC_CPUMASK_ORBIT(smp_invmask, cpu);
346 info->mode = INVSTORE;
348 tmpmask = pmap->pm_active; /* volatile (bits may be cleared) */
350 CPUMASK_ANDMASK(tmpmask, smp_active_mask);
353 * If ptep is NULL the operation can be semi-synchronous, which means
354 * we can improve performance by flagging and removing idle cpus
355 * (see the idleinvlclr function in mp_machdep.c).
357 * Typically kernel page table operation is semi-synchronous.
360 smp_smurf_idleinvlclr(&tmpmask);
361 CPUMASK_ORBIT(tmpmask, cpu);
362 info->mask = tmpmask;
365 * Command may start executing the moment 'done' is initialized,
366 * disable current cpu interrupt to prevent 'done' field from
367 * changing (other cpus can't clear done bits until the originating
368 * cpu clears its mask bit, but other cpus CAN start clearing their
372 info->sigmask = tmpmask;
376 rflags = read_rflags();
379 ATOMIC_CPUMASK_COPY(info->done, tmpmask);
380 /* execution can begin here due to races */
383 * Pass our copy of the done bits (so they don't change out from
384 * under us) to generate the Xinvltlb interrupt on the targets.
386 smp_invlpg(&tmpmask);
388 KKASSERT(info->mode == INVDONE);
391 * Target cpus will be in their loop exiting concurrently with our
392 * cleanup. They will not lose the bitmask they obtained before so
393 * we can safely clear this bit.
395 ATOMIC_CPUMASK_NANDBIT(smp_invmask, cpu);
396 write_rflags(rflags);
397 pmap_inval_done(pmap);
403 * API function - invalidate the pte at (va) and replace *ptep with npte
404 * atomically only if *ptep equals opte, across the pmap's active cpus.
406 * Returns 1 on success, 0 on failure (caller typically retries).
409 pmap_inval_smp_cmpset(pmap_t pmap, vm_offset_t va, pt_entry_t *ptep,
410 pt_entry_t opte, pt_entry_t npte)
412 globaldata_t gd = mycpu;
413 pmap_inval_info_t *info;
415 int cpu = gd->gd_cpuid;
417 unsigned long rflags;
420 * Initialize invalidation for pmap and enter critical section.
424 pmap_inval_init(pmap);
427 * Shortcut single-cpu case if possible.
429 if (CPUMASK_CMPMASKEQ(pmap->pm_active, gd->gd_cpumask)) {
430 if (atomic_cmpset_long(ptep, opte, npte)) {
431 if (va == (vm_offset_t)-1)
434 cpu_invlpg((void *)va);
435 pmap_inval_done(pmap);
438 pmap_inval_done(pmap);
444 * We need a critical section to prevent getting preempted while
445 * we setup our command. A preemption might execute its own
446 * pmap_inval*() command and create confusion below.
448 info = &invinfo[cpu];
451 * We must wait for other cpus which may still be finishing
452 * up a prior operation.
454 while (CPUMASK_TESTNZERO(info->done)) {
456 if (loopwdog(info)) {
458 loopdebug("B", info);
459 /* XXX recover from possible bug */
460 CPUMASK_ASSZERO(info->done);
465 KKASSERT(info->mode == INVDONE);
468 * Must set our cpu in the invalidation scan mask before
469 * any possibility of [partial] execution (remember, XINVLTLB
470 * can interrupt a critical section).
472 ATOMIC_CPUMASK_ORBIT(smp_invmask, cpu);
475 info->npgs = 1; /* unused */
482 info->mode = INVCMPSET;
485 tmpmask = pmap->pm_active; /* volatile */
487 CPUMASK_ANDMASK(tmpmask, smp_active_mask);
488 CPUMASK_ORBIT(tmpmask, cpu);
489 info->mask = tmpmask;
492 * Command may start executing the moment 'done' is initialized,
493 * disable current cpu interrupt to prevent 'done' field from
494 * changing (other cpus can't clear done bits until the originating
495 * cpu clears its mask bit).
498 info->sigmask = tmpmask;
502 rflags = read_rflags();
505 ATOMIC_CPUMASK_COPY(info->done, tmpmask);
508 * Pass our copy of the done bits (so they don't change out from
509 * under us) to generate the Xinvltlb interrupt on the targets.
511 smp_invlpg(&tmpmask);
512 success = info->success;
513 KKASSERT(info->mode == INVDONE);
515 ATOMIC_CPUMASK_NANDBIT(smp_invmask, cpu);
516 write_rflags(rflags);
517 pmap_inval_done(pmap);
523 pmap_inval_bulk_init(pmap_inval_bulk_t *bulk, struct pmap *pmap)
532 pmap_inval_bulk(pmap_inval_bulk_t *bulk, vm_offset_t va,
533 pt_entry_t *ptep, pt_entry_t npte)
538 * Degenerate case, localized or we don't care (e.g. because we
539 * are jacking the entire page table) or the pmap is not in-use
540 * by anyone. No invalidations are done on any cpu.
543 pte = atomic_swap_long(ptep, npte);
548 * If it isn't the kernel pmap we execute the operation synchronously
549 * on all cpus belonging to the pmap, which avoids concurrency bugs in
550 * the hw related to changing pte's out from under threads.
552 * Eventually I would like to implement streaming pmap invalidation
553 * for user pmaps to reduce mmap/munmap overheads for heavily-loaded
556 if (bulk->pmap != &kernel_pmap) {
557 pte = pmap_inval_smp(bulk->pmap, va, 1, ptep, npte);
562 * This is the kernel_pmap. All unmap operations presume that there
563 * are no other cpus accessing the addresses in question. Implement
564 * the bulking algorithm. collect the required information and
565 * synchronize once at the end.
567 pte = atomic_swap_long(ptep, npte);
568 if (va == (vm_offset_t)-1) {
570 } else if (bulk->va_beg == bulk->va_end) {
572 bulk->va_end = va + PAGE_SIZE;
573 } else if (va == bulk->va_end) {
574 bulk->va_end = va + PAGE_SIZE;
576 bulk->va_beg = (vm_offset_t)-1;
579 pmap_inval_bulk_flush(bulk);
581 if (va == (vm_offset_t)-1) {
586 bulk->va_end = va + PAGE_SIZE;
596 pmap_inval_bulk_flush(pmap_inval_bulk_t *bulk)
601 pmap_inval_bulk_count += (bulk->count - 1);
602 if (bulk->va_beg != bulk->va_end) {
603 if (bulk->va_beg == (vm_offset_t)-1) {
604 pmap_inval_smp(bulk->pmap, bulk->va_beg, 1, NULL, 0);
608 n = (bulk->va_end - bulk->va_beg) >> PAGE_SHIFT;
609 pmap_inval_smp(bulk->pmap, bulk->va_beg, n, NULL, 0);
618 * Called with a critical section held and interrupts enabled.
621 pmap_inval_intr(cpumask_t *cpumaskp, int toolong)
623 globaldata_t gd = mycpu;
624 pmap_inval_info_t *info;
630 * Check all cpus for invalidations we may need to service.
636 while (CPUMASK_TESTNZERO(cpumask)) {
637 int n = BSFCPUMASK(cpumask);
640 KKASSERT(n >= 0 && n < MAXCPU);
643 CPUMASK_NANDBIT(cpumask, n);
647 * Due to interrupts/races we can catch a new operation
648 * in an older interrupt. A fence is needed once we detect
649 * the (not) done bit.
651 if (!CPUMASK_TESTBIT(info->done, cpu))
656 kprintf("pminvl %d->%d %08jx %08jx mode=%d\n",
657 cpu, n, info->done.ary[0], info->mask.ary[0],
663 * info->mask and info->done always contain the originating
664 * cpu until the originator is done. Targets may still be
665 * present in info->done after the originator is done (they
666 * will be finishing up their loops).
668 * Clear info->mask bits on other cpus to indicate that they
669 * have quiesced (entered the loop). Once the other mask bits
670 * are clear we can execute the operation on the original,
671 * then clear the mask and done bits on the originator. The
672 * targets will then finish up their side and clear their
675 * The command is considered 100% done when all done bits have
680 * Command state machine for 'other' cpus.
682 if (CPUMASK_TESTBIT(info->mask, cpu)) {
684 * Other cpu indicate to originator that they
687 ATOMIC_CPUMASK_NANDBIT(info->mask, cpu);
689 } else if (info->ptep &&
690 CPUMASK_TESTBIT(info->mask, n)) {
692 * Other cpu must wait for the originator (n)
693 * to complete its command if ptep is not NULL.
698 * Other cpu detects that the originator has
699 * completed its command, or there was no
702 * Now that the page table entry has changed,
703 * we can follow up with our own invalidation.
705 vm_offset_t va = info->va;
708 if (va == (vm_offset_t)-1 ||
709 info->npgs > MAX_INVAL_PAGES) {
712 for (npgs = info->npgs; npgs; --npgs) {
713 cpu_invlpg((void *)va);
717 ATOMIC_CPUMASK_NANDBIT(info->done, cpu);
718 /* info invalid now */
719 /* loopme left alone */
721 } else if (CPUMASK_TESTBIT(info->mask, cpu)) {
723 * Originator is waiting for other cpus
725 if (CPUMASK_CMPMASKNEQ(info->mask, gd->gd_cpumask)) {
727 * Originator waits for other cpus to enter
728 * their loop (aka quiesce).
730 * If this bugs out the IPI may have been lost,
731 * try to reissue by resetting our own
732 * reentrancy bit and clearing the smurf mask
733 * for the cpus that did not respond, then
738 if (loopwdog(info)) {
740 loopdebug("C", info);
741 /* XXX recover from possible bug */
742 mdcpu->gd_xinvaltlb = 0;
743 ATOMIC_CPUMASK_NANDMASK(smp_smurf_mask,
746 smp_invlpg(&smp_active_mask);
752 * Originator executes operation and clears
753 * mask to allow other cpus to finish.
755 KKASSERT(info->mode != INVDONE);
756 if (info->mode == INVSTORE) {
758 info->opte = atomic_swap_long(info->ptep, info->npte);
760 ATOMIC_CPUMASK_NANDBIT(info->mask, cpu);
763 if (atomic_cmpset_long(info->ptep,
764 info->opte, info->npte)) {
770 ATOMIC_CPUMASK_NANDBIT(info->mask, cpu);
777 * Originator does not have to wait for the other
778 * cpus to finish. It clears its done bit. A new
779 * command will not be initiated by the originator
780 * until the other cpus have cleared their done bits
783 vm_offset_t va = info->va;
786 if (va == (vm_offset_t)-1 ||
787 info->npgs > MAX_INVAL_PAGES) {
790 for (npgs = info->npgs; npgs; --npgs) {
791 cpu_invlpg((void *)va);
796 /* leave loopme alone */
797 /* other cpus may still be finishing up */
798 /* can't race originator since that's us */
799 info->mode = INVDONE;
800 ATOMIC_CPUMASK_NANDBIT(info->done, cpu);