2 * Copyright (c) 1982, 1986 The Regents of the University of California.
3 * Copyright (c) 1989, 1990 William Jolitz
4 * Copyright (c) 1994 John Dyson
7 * This code is derived from software contributed to Berkeley by
8 * the Systems Programming Group of the University of Utah Computer
9 * Science Department, and William Jolitz.
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 * must display the following acknowledgement:
21 * This product includes software developed by the University of
22 * California, Berkeley and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91
40 * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
48 #include "opt_reset.h"
52 #include <sys/param.h>
53 #include <sys/systm.h>
56 #include <sys/kernel.h>
59 #include <sys/malloc.h>
61 #include <sys/mutex.h>
62 #include <sys/pioctl.h>
64 #include <sys/sf_buf.h>
66 #include <sys/sched.h>
67 #include <sys/sysctl.h>
68 #include <sys/unistd.h>
69 #include <sys/vnode.h>
70 #include <sys/vmmeter.h>
72 #include <machine/cpu.h>
73 #include <machine/cputypes.h>
74 #include <machine/md_var.h>
75 #include <machine/pcb.h>
76 #include <machine/pcb_ext.h>
77 #include <machine/smp.h>
78 #include <machine/vm86.h>
81 #include <machine/elan_mmcr.h>
85 #include <vm/vm_extern.h>
86 #include <vm/vm_kern.h>
87 #include <vm/vm_page.h>
88 #include <vm/vm_map.h>
89 #include <vm/vm_param.h>
92 #include <xen/hypervisor.h>
95 #include <pc98/cbus/cbus.h>
97 #include <i386/isa/isa.h>
101 #include <machine/xbox.h>
105 #define NSFBUFS (512 + maxusers * 16)
108 static void cpu_reset_real(void);
110 static void cpu_reset_proxy(void);
111 static u_int cpu_reset_proxyid;
112 static volatile u_int cpu_reset_proxy_active;
114 static void sf_buf_init(void *arg);
115 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL);
117 LIST_HEAD(sf_head, sf_buf);
120 * A hash table of active sendfile(2) buffers
122 static struct sf_head *sf_buf_active;
123 static u_long sf_buf_hashmask;
125 #define SF_BUF_HASH(m) (((m) - vm_page_array) & sf_buf_hashmask)
127 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
128 static u_int sf_buf_alloc_want;
131 * A lock used to synchronize access to the hash table and free list
133 static struct mtx sf_buf_lock;
135 extern int _ucodesel, _udatasel;
138 * Finish a fork operation, with process p2 nearly set up.
139 * Copy and update the pcb, set up the stack so that the child
140 * ready to run and return to user mode.
143 cpu_fork(td1, p2, td2, flags)
144 register struct thread *td1;
145 register struct proc *p2;
149 register struct proc *p1;
157 if ((flags & RFPROC) == 0) {
158 if ((flags & RFMEM) == 0) {
159 /* unshare user LDT */
160 struct mdproc *mdp1 = &p1->p_md;
161 struct proc_ldt *pldt, *pldt1;
163 mtx_lock_spin(&dt_lock);
164 if ((pldt1 = mdp1->md_ldt) != NULL &&
165 pldt1->ldt_refcnt > 1) {
166 pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
168 panic("could not copy LDT");
171 user_ldt_deref(pldt1);
173 mtx_unlock_spin(&dt_lock);
178 /* Ensure that p1's pcb is up to date. */
179 if (td1 == curthread)
180 td1->td_pcb->pcb_gs = rgs();
182 savecrit = intr_disable();
183 if (PCPU_GET(fpcurthread) == td1)
184 npxsave(&td1->td_pcb->pcb_save);
185 intr_restore(savecrit);
188 /* Point the pcb to the top of the stack */
189 pcb2 = (struct pcb *)(td2->td_kstack +
190 td2->td_kstack_pages * PAGE_SIZE) - 1;
194 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
196 /* Point mdproc and then copy over td1's contents */
198 bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
201 * Create a new fresh stack for the new process.
202 * Copy the trap frame for the return to user mode as if from a
203 * syscall. This copies most of the user mode register values.
204 * The -16 is so we can expand the trapframe if we go to vm86.
206 td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - 16) - 1;
207 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
209 td2->td_frame->tf_eax = 0; /* Child returns zero */
210 td2->td_frame->tf_eflags &= ~PSL_C; /* success */
211 td2->td_frame->tf_edx = 1;
214 * If the parent process has the trap bit set (i.e. a debugger had
215 * single stepped the process to the system call), we need to clear
216 * the trap flag from the new frame unless the debugger had set PF_FORK
217 * on the parent. Otherwise, the child will receive a (likely
218 * unexpected) SIGTRAP when it executes the first instruction after
219 * returning to userland.
221 if ((p1->p_pfsflags & PF_FORK) == 0)
222 td2->td_frame->tf_eflags &= ~PSL_T;
225 * Set registers for trampoline to user mode. Leave space for the
226 * return address on stack. These are the kernel mode register values.
229 pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdpt);
231 pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdir);
234 pcb2->pcb_esi = (int)fork_return; /* fork_trampoline argument */
236 pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
237 pcb2->pcb_ebx = (int)td2; /* fork_trampoline argument */
238 pcb2->pcb_eip = (int)fork_trampoline;
239 pcb2->pcb_psl = PSL_KERNEL; /* ints disabled */
241 * pcb2->pcb_dr*: cloned above.
242 * pcb2->pcb_savefpu: cloned above.
243 * pcb2->pcb_flags: cloned above.
244 * pcb2->pcb_onfault: cloned above (always NULL here?).
245 * pcb2->pcb_gs: cloned above.
246 * pcb2->pcb_ext: cleared below.
250 * XXX don't copy the i/o pages. this should probably be fixed.
254 /* Copy the LDT, if necessary. */
255 mtx_lock_spin(&dt_lock);
256 if (mdp2->md_ldt != NULL) {
258 mdp2->md_ldt->ldt_refcnt++;
260 mdp2->md_ldt = user_ldt_alloc(mdp2,
261 mdp2->md_ldt->ldt_len);
262 if (mdp2->md_ldt == NULL)
263 panic("could not copy LDT");
266 mtx_unlock_spin(&dt_lock);
268 /* Setup to release spin count in fork_exit(). */
269 td2->td_md.md_spinlock_count = 1;
271 * XXX XEN need to check on PSL_USER is handled
274 td2->td_md.md_saved_flags = 0;
276 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
279 * Now, cpu_switch() can schedule the new process.
280 * pcb_esp is loaded pointing to the cpu_switch() stack frame
281 * containing the return address when exiting cpu_switch.
282 * This will normally be to fork_trampoline(), which will have
283 * %ebx loaded with the new proc's pointer. fork_trampoline()
284 * will set up a stack to call fork_return(p, frame); to complete
285 * the return to user-mode.
290 * Intercept the return address from a freshly forked process that has NOT
291 * been scheduled yet.
293 * This is needed to make kernel threads stay in kernel mode.
296 cpu_set_fork_handler(td, func, arg)
298 void (*func)(void *);
302 * Note that the trap frame follows the args, so the function
303 * is really called like this: func(arg, frame);
305 td->td_pcb->pcb_esi = (int) func; /* function */
306 td->td_pcb->pcb_ebx = (int) arg; /* first arg */
310 cpu_exit(struct thread *td)
314 * If this process has a custom LDT, release it. Reset pc->pcb_gs
315 * and %gs before we free it in case they refer to an LDT entry.
317 mtx_lock_spin(&dt_lock);
318 if (td->td_proc->p_md.md_ldt) {
319 td->td_pcb->pcb_gs = _udatasel;
323 mtx_unlock_spin(&dt_lock);
327 cpu_thread_exit(struct thread *td)
331 if (td == PCPU_GET(fpcurthread))
335 /* Disable any hardware breakpoints. */
336 if (td->td_pcb->pcb_flags & PCB_DBREGS) {
338 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
343 cpu_thread_clean(struct thread *td)
348 if (pcb->pcb_ext != NULL) {
349 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
351 * XXX do we need to move the TSS off the allocated pages
352 * before freeing them? (not done here)
354 kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ext,
361 cpu_thread_swapin(struct thread *td)
366 cpu_thread_swapout(struct thread *td)
371 cpu_thread_alloc(struct thread *td)
374 td->td_pcb = (struct pcb *)(td->td_kstack +
375 td->td_kstack_pages * PAGE_SIZE) - 1;
376 td->td_frame = (struct trapframe *)((caddr_t)td->td_pcb - 16) - 1;
377 td->td_pcb->pcb_ext = NULL;
381 cpu_thread_free(struct thread *td)
384 cpu_thread_clean(td);
388 * Initialize machine state (pcb and trap frame) for a new thread about to
389 * upcall. Put enough state in the new thread's PCB to get it to go back
390 * userret(), where we can intercept it again to set the return (upcall)
391 * Address and stack, along with those from upcals that are from other sources
392 * such as those generated in thread_userret() itself.
395 cpu_set_upcall(struct thread *td, struct thread *td0)
399 /* Point the pcb to the top of the stack. */
403 * Copy the upcall pcb. This loads kernel regs.
404 * Those not loaded individually below get their default
407 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
408 pcb2->pcb_flags &= ~(PCB_NPXTRAP|PCB_NPXINITDONE);
411 * Create a new fresh stack for the new thread.
413 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
415 /* If the current thread has the trap bit set (i.e. a debugger had
416 * single stepped the process to the system call), we need to clear
417 * the trap flag from the new frame. Otherwise, the new thread will
418 * receive a (likely unexpected) SIGTRAP when it executes the first
419 * instruction after returning to userland.
421 td->td_frame->tf_eflags &= ~PSL_T;
424 * Set registers for trampoline to user mode. Leave space for the
425 * return address on stack. These are the kernel mode register values.
428 pcb2->pcb_esi = (int)fork_return; /* trampoline arg */
430 pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
431 pcb2->pcb_ebx = (int)td; /* trampoline arg */
432 pcb2->pcb_eip = (int)fork_trampoline;
433 pcb2->pcb_psl &= ~(PSL_I); /* interrupts must be disabled */
434 pcb2->pcb_gs = rgs();
436 * If we didn't copy the pcb, we'd need to do the following registers:
437 * pcb2->pcb_cr3: cloned above.
438 * pcb2->pcb_dr*: cloned above.
439 * pcb2->pcb_savefpu: cloned above.
440 * pcb2->pcb_flags: cloned above.
441 * pcb2->pcb_onfault: cloned above (always NULL here?).
442 * pcb2->pcb_gs: cloned above.
443 * pcb2->pcb_ext: cleared below.
445 pcb2->pcb_ext = NULL;
447 /* Setup to release spin count in fork_exit(). */
448 td->td_md.md_spinlock_count = 1;
450 td->td_md.md_saved_flags = 0;
452 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
457 * Set that machine state for performing an upcall that has to
458 * be done in thread_userret() so that those upcalls generated
459 * in thread_userret() itself can be done as well.
462 cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg,
467 * Do any extra cleaning that needs to be done.
468 * The thread may have optional components
469 * that are not present in a fresh thread.
470 * This may be a recycled thread so make it look
471 * as though it's newly allocated.
473 cpu_thread_clean(td);
476 * Set the trap frame to point at the beginning of the uts
479 td->td_frame->tf_ebp = 0;
480 td->td_frame->tf_esp =
481 (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
482 td->td_frame->tf_eip = (int)entry;
485 * Pass the address of the mailbox for this kse to the uts
486 * function as a parameter on the stack.
488 suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
493 cpu_set_user_tls(struct thread *td, void *tls_base)
495 struct segment_descriptor sd;
499 * Construct a descriptor and store it in the pcb for
500 * the next context switch. Also store it in the gdt
501 * so that the load of tf_fs into %fs will activate it
502 * at return to userland.
504 base = (uint32_t)tls_base;
505 sd.sd_lobase = base & 0xffffff;
506 sd.sd_hibase = (base >> 24) & 0xff;
507 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
509 sd.sd_type = SDT_MEMRWA;
517 td->td_pcb->pcb_gsd = sd;
518 if (td == curthread) {
519 PCPU_GET(fsgs_gdt)[1] = sd;
520 load_gs(GSEL(GUGS_SEL, SEL_UPL));
527 * Convert kernel VA to physical address
534 pa = pmap_kextract((vm_offset_t)addr);
536 panic("kvtop: zero page frame");
545 cpu_reset_proxy_active = 1;
546 while (cpu_reset_proxy_active == 1)
547 ; /* Wait for other cpu to see that we've started */
548 stop_cpus((1<<cpu_reset_proxyid));
549 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
559 if (arch_i386_is_xbox) {
560 /* Kick the PIC16L, it can reboot the box */
570 map = PCPU_GET(other_cpus) & ~stopped_cpus;
572 printf("cpu_reset: Stopping other CPUs\n");
576 if (PCPU_GET(cpuid) != 0) {
577 cpu_reset_proxyid = PCPU_GET(cpuid);
578 cpustop_restartfunc = cpu_reset_proxy;
579 cpu_reset_proxy_active = 0;
580 printf("cpu_reset: Restarting BSP\n");
582 /* Restart CPU #0. */
583 /* XXX: restart_cpus(1 << 0); */
584 atomic_store_rel_int(&started_cpus, (1 << 0));
587 while (cpu_reset_proxy_active == 0 && cnt < 10000000)
588 cnt++; /* Wait for BSP to announce restart */
589 if (cpu_reset_proxy_active == 0)
590 printf("cpu_reset: Failed to restart BSP\n");
592 cpu_reset_proxy_active = 2;
608 struct region_descriptor null_idt;
615 if (smp_processor_id() == 0)
616 HYPERVISOR_shutdown(SHUTDOWN_reboot);
618 HYPERVISOR_shutdown(SHUTDOWN_poweroff);
621 if (elan_mmcr != NULL)
622 elan_mmcr->RESCFG = 1;
625 if (cpu == CPU_GEODE1100) {
626 /* Attempt Geode's own reset */
627 outl(0xcf8, 0x80009044ul);
633 * Attempt to do a CPU reset via CPU reset port.
635 if ((inb(0x35) & 0xa0) != 0xa0) {
636 outb(0x37, 0x0f); /* SHUT0 = 0. */
637 outb(0x37, 0x0b); /* SHUT1 = 0. */
639 outb(0xf0, 0x00); /* Reset. */
641 #if !defined(BROKEN_KEYBOARD_RESET)
643 * Attempt to do a CPU reset via the keyboard controller,
644 * do not turn off GateA20, as any machine that fails
645 * to do the reset here would then end up in no man's land.
647 outb(IO_KBD + 4, 0xFE);
648 DELAY(500000); /* wait 0.5 sec to see if that did it */
652 * Attempt to force a reset via the Reset Control register at
653 * I/O port 0xcf9. Bit 2 forces a system reset when it
654 * transitions from 0 to 1. Bit 1 selects the type of reset
655 * to attempt: 0 selects a "soft" reset, and 1 selects a
656 * "hard" reset. We try a "hard" reset. The first write sets
657 * bit 1 to select a "hard" reset and clears bit 2. The
658 * second write forces a 0 -> 1 transition in bit 2 to trigger
663 DELAY(500000); /* wait 0.5 sec to see if that did it */
666 * Attempt to force a reset via the Fast A20 and Init register
667 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate.
668 * Bit 0 asserts INIT# when set to 1. We are careful to only
669 * preserve bit 1 while setting bit 0. We also must clear bit
670 * 0 before setting it if it isn't already clear.
675 outb(0x92, b & 0xfe);
677 DELAY(500000); /* wait 0.5 sec to see if that did it */
681 printf("No known reset method worked, attempting CPU shutdown\n");
682 DELAY(1000000); /* wait 1 sec for printf to complete */
685 null_idt.rd_limit = 0;
686 null_idt.rd_base = 0;
689 /* "good night, sweet prince .... <THUNK!>" */
697 * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
700 sf_buf_init(void *arg)
702 struct sf_buf *sf_bufs;
707 TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
709 sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
710 TAILQ_INIT(&sf_buf_freelist);
711 sf_base = kmem_alloc_nofault(kernel_map, nsfbufs * PAGE_SIZE);
712 sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
714 for (i = 0; i < nsfbufs; i++) {
715 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
716 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
718 sf_buf_alloc_want = 0;
719 mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
723 * Invalidate the cache lines that may belong to the page, if
724 * (possibly old) mapping of the page by sf buffer exists. Returns
725 * TRUE when mapping was found and cache invalidated.
728 sf_buf_invalidate_cache(vm_page_t m)
730 struct sf_head *hash_list;
734 hash_list = &sf_buf_active[SF_BUF_HASH(m)];
736 mtx_lock(&sf_buf_lock);
737 LIST_FOREACH(sf, hash_list, list_entry) {
740 * Use pmap_qenter to update the pte for
741 * existing mapping, in particular, the PAT
742 * settings are recalculated.
744 pmap_qenter(sf->kva, &m, 1);
745 pmap_invalidate_cache_range(sf->kva, sf->kva +
751 mtx_unlock(&sf_buf_lock);
756 * Get an sf_buf from the freelist. May block if none are available.
759 sf_buf_alloc(struct vm_page *m, int flags)
761 pt_entry_t opte, *ptep;
762 struct sf_head *hash_list;
765 cpumask_t cpumask, other_cpus;
769 KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
770 ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
771 hash_list = &sf_buf_active[SF_BUF_HASH(m)];
772 mtx_lock(&sf_buf_lock);
773 LIST_FOREACH(sf, hash_list, list_entry) {
776 if (sf->ref_count == 1) {
777 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
779 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
788 while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
789 if (flags & SFB_NOWAIT)
792 mbstat.sf_allocwait++;
793 error = msleep(&sf_buf_freelist, &sf_buf_lock,
794 (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
798 * If we got a signal, don't risk going back to sleep.
803 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
805 LIST_REMOVE(sf, list_entry);
806 LIST_INSERT_HEAD(hash_list, sf, list_entry);
810 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
813 * Update the sf_buf's virtual-to-physical mapping, flushing the
814 * virtual address from the TLB. Since the reference count for
815 * the sf_buf's old mapping was zero, that mapping is not
816 * currently in use. Consequently, there is no need to exchange
817 * the old and new PTEs atomically, even under PAE.
819 ptep = vtopte(sf->kva);
822 PT_SET_MA(sf->kva, xpmap_ptom(VM_PAGE_TO_PHYS(m)) | pgeflag
823 | PG_RW | PG_V | pmap_cache_bits(m->md.pat_mode, 0));
825 *ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V |
826 pmap_cache_bits(m->md.pat_mode, 0);
830 * Avoid unnecessary TLB invalidations: If the sf_buf's old
831 * virtual-to-physical mapping was not used, then any processor
832 * that has invalidated the sf_buf's virtual address from its TLB
833 * since the last used mapping need not invalidate again.
836 if ((opte & (PG_V | PG_A)) == (PG_V | PG_A))
840 cpumask = PCPU_GET(cpumask);
841 if ((sf->cpumask & cpumask) == 0) {
842 sf->cpumask |= cpumask;
845 if ((flags & SFB_CPUPRIVATE) == 0) {
846 other_cpus = PCPU_GET(other_cpus) & ~sf->cpumask;
847 if (other_cpus != 0) {
848 sf->cpumask |= other_cpus;
849 smp_masked_invlpg(other_cpus, sf->kva);
854 if ((opte & (PG_V | PG_A)) == (PG_V | PG_A))
855 pmap_invalidate_page(kernel_pmap, sf->kva);
858 mtx_unlock(&sf_buf_lock);
863 * Remove a reference from the given sf_buf, adding it to the free
864 * list when its reference count reaches zero. A freed sf_buf still,
865 * however, retains its virtual-to-physical mapping until it is
866 * recycled or reactivated by sf_buf_alloc(9).
869 sf_buf_free(struct sf_buf *sf)
872 mtx_lock(&sf_buf_lock);
874 if (sf->ref_count == 0) {
875 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
879 * Xen doesn't like having dangling R/W mappings
881 pmap_qremove(sf->kva, 1);
883 LIST_REMOVE(sf, list_entry);
885 if (sf_buf_alloc_want > 0)
886 wakeup_one(&sf_buf_freelist);
888 mtx_unlock(&sf_buf_lock);
892 * Software interrupt handler for queued VM system processing.
897 if (busdma_swi_pending != 0)
902 * Tell whether this address is in some physical memory region.
903 * Currently used by the kernel coredump code in order to avoid
904 * dumping the ``ISA memory hole'' which could cause indefinite hangs,
905 * or other unpredictable behaviour.
909 is_physical_memory(vm_paddr_t addr)
913 /* The ISA ``memory hole''. */
914 if (addr >= 0xa0000 && addr < 0x100000)
919 * stuff other tests for known memory-mapped devices (PCI?)