freebsd/sys/vm/vm_glue.c

/*-
 * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * The Mach Operating System project at Carnegie-Mellon University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)vm_glue.c	8.6 (Berkeley) 1/5/94
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_vm.h"
#include "opt_kstack_pages.h"
#include "opt_kstack_max_pages.h"
#include "opt_kstack_usage_prof.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sf_buf.h>
#include <sys/shm.h>
#include <sys/vmmeter.h>
#include <sys/vmem.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/_kstack_cache.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/unistd.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_pager.h>
#include <vm/swap_pager.h>

#include <machine/cpu.h>

/*
 * MPSAFE
 *
 * WARNING!  This code calls vm_map_check_protection() which only checks
 * the associated vm_map_entry range.  It does not determine whether the
 * contents of the memory is actually readable or writable.  In most cases
 * just checking the vm_map_entry is sufficient within the kernel's address
 * space.
 */
int
kernacc(void *addr, int len, int rw)
{
	boolean_t rv;
	vm_offset_t saddr, eaddr;
	vm_prot_t prot;

	KASSERT((rw & ~VM_PROT_ALL) == 0,
	    ("illegal ``rw'' argument to kernacc (%x)\n", rw));

	if ((vm_offset_t)addr + len > kernel_map->max_offset ||
	    (vm_offset_t)addr + len < (vm_offset_t)addr)
		return (FALSE);

	prot = rw;
	saddr = trunc_page((vm_offset_t)addr);
	eaddr = round_page((vm_offset_t)addr + len);
	vm_map_lock_read(kernel_map);
	rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
	vm_map_unlock_read(kernel_map);
	return (rv == TRUE);
}

/*
 * MPSAFE
 *
 * WARNING!  This code calls vm_map_check_protection() which only checks
 * the associated vm_map_entry range.  It does not determine whether the
 * contents of the memory is actually readable or writable.  vmapbuf(),
 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be
 * used in conjunction with this call.
 */
int
useracc(void *addr, int len, int rw)
{
	boolean_t rv;
	vm_prot_t prot;
	vm_map_t map;

	KASSERT((rw & ~VM_PROT_ALL) == 0,
	    ("illegal ``rw'' argument to useracc (%x)\n", rw));
	prot = rw;
	map = &curproc->p_vmspace->vm_map;
	if ((vm_offset_t)addr + len > vm_map_max(map) ||
	    (vm_offset_t)addr + len < (vm_offset_t)addr) {
		return (FALSE);
	}
	vm_map_lock_read(map);
	rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
	    round_page((vm_offset_t)addr + len), prot);
	vm_map_unlock_read(map);
	return (rv == TRUE);
}

int
vslock(void *addr, size_t len)
{
	vm_offset_t end, last, start;
	vm_size_t npages;
	int error;

	last = (vm_offset_t)addr + len;
	start = trunc_page((vm_offset_t)addr);
	end = round_page(last);
	if (last < (vm_offset_t)addr || end < (vm_offset_t)addr)
		return (EINVAL);
	npages = atop(end - start);
	if (npages > vm_page_max_wired)
		return (ENOMEM);
#if 0
	/*
	 * XXX - not yet
	 *
	 * The limit for transient usage of wired pages should be
	 * larger than for "permanent" wired pages (mlock()).
	 *
	 * Also, the sysctl code, which is the only present user
	 * of vslock(), does a hard loop on EAGAIN.
	 */
	if (npages + vm_cnt.v_wire_count > vm_page_max_wired)
		return (EAGAIN);
#endif
	error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end,
	    VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
	/*
	 * Return EFAULT on error to match copy{in,out}() behaviour
	 * rather than returning ENOMEM like mlock() would.
	 */
	return (error == KERN_SUCCESS ? 0 : EFAULT);
}

void
vsunlock(void *addr, size_t len)
{

	/* Rely on the parameter sanity checks performed by vslock(). */
	(void)vm_map_unwire(&curproc->p_vmspace->vm_map,
	    trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len),
	    VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
}

/*
 * Pin the page contained within the given object at the given offset.  If the
 * page is not resident, allocate and load it using the given object's pager.
 * Return the pinned page if successful; otherwise, return NULL.
 */
static vm_page_t
vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
{
	vm_page_t m;
	vm_pindex_t pindex;
	int rv;

	VM_OBJECT_WLOCK(object);
	pindex = OFF_TO_IDX(offset);
	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
	if (m->valid != VM_PAGE_BITS_ALL) {
		vm_page_xbusy(m);
		rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
		if (rv != VM_PAGER_OK) {
			vm_page_lock(m);
			vm_page_free(m);
			vm_page_unlock(m);
			m = NULL;
			goto out;
		}
		vm_page_xunbusy(m);
	}
	vm_page_lock(m);
	vm_page_hold(m);
	vm_page_activate(m);
	vm_page_unlock(m);
out:
	VM_OBJECT_WUNLOCK(object);
	return (m);
}

/*
 * Return a CPU private mapping to the page at the given offset within the
 * given object.  The page is pinned before it is mapped.
 */
struct sf_buf *
vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset)
{
	vm_page_t m;

	m = vm_imgact_hold_page(object, offset);
	if (m == NULL)
		return (NULL);
	sched_pin();
	return (sf_buf_alloc(m, SFB_CPUPRIVATE));
}

/*
 * Destroy the given CPU private mapping and unpin the page that it mapped.
 */
void
vm_imgact_unmap_page(struct sf_buf *sf)
{
	vm_page_t m;

	m = sf_buf_page(sf);
	sf_buf_free(sf);
	sched_unpin();
	vm_page_lock(m);
	vm_page_unhold(m);
	vm_page_unlock(m);
}

void
vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
{

	pmap_sync_icache(map->pmap, va, sz);
}

struct kstack_cache_entry *kstack_cache;
static int kstack_cache_size = 128;
static int kstacks;
static struct mtx kstack_cache_mtx;
MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF);

SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0,
    "");
SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0,
    "");

/*
 * Create the kernel stack (including pcb for i386) for a new thread.
 * This routine directly affects the fork perf for a process and
 * create performance for a thread.
 */
int
vm_thread_new(struct thread *td, int pages)
{
	vm_object_t ksobj;
	vm_offset_t ks;
	vm_page_t ma[KSTACK_MAX_PAGES];
	struct kstack_cache_entry *ks_ce;
	int i;

	/* Bounds check */
	if (pages <= 1)
		pages = kstack_pages;
	else if (pages > KSTACK_MAX_PAGES)
		pages = KSTACK_MAX_PAGES;

	if (pages == kstack_pages) {
		mtx_lock(&kstack_cache_mtx);
		if (kstack_cache != NULL) {
			ks_ce = kstack_cache;
			kstack_cache = ks_ce->next_ks_entry;
			mtx_unlock(&kstack_cache_mtx);

			td->td_kstack_obj = ks_ce->ksobj;
			td->td_kstack = (vm_offset_t)ks_ce;
			td->td_kstack_pages = kstack_pages;
			return (1);
		}
		mtx_unlock(&kstack_cache_mtx);
	}

	/*
	 * Allocate an object for the kstack.
	 */
	ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
	
	/*
	 * Get a kernel virtual address for this thread's kstack.
	 */
#if defined(__mips__)
	/*
	 * We need to align the kstack's mapped address to fit within
	 * a single TLB entry.
	 */
	if (vmem_xalloc(kernel_arena, (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE,
	    PAGE_SIZE * 2, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX,
	    M_BESTFIT | M_NOWAIT, &ks)) {
		ks = 0;
	}
#else
	ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
#endif
	if (ks == 0) {
		printf("vm_thread_new: kstack allocation failed\n");
		vm_object_deallocate(ksobj);
		return (0);
	}

	atomic_add_int(&kstacks, 1);
	if (KSTACK_GUARD_PAGES != 0) {
		pmap_qremove(ks, KSTACK_GUARD_PAGES);
		ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
	}
	td->td_kstack_obj = ksobj;
	td->td_kstack = ks;
	/*
	 * Knowing the number of pages allocated is useful when you
	 * want to deallocate them.
	 */
	td->td_kstack_pages = pages;
	/* 
	 * For the length of the stack, link in a real page of ram for each
	 * page of stack.
	 */
	VM_OBJECT_WLOCK(ksobj);
	(void)vm_page_grab_pages(ksobj, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY |
	    VM_ALLOC_WIRED, ma, pages);
	for (i = 0; i < pages; i++)
		ma[i]->valid = VM_PAGE_BITS_ALL;
	VM_OBJECT_WUNLOCK(ksobj);
	pmap_qenter(ks, ma, pages);
	return (1);
}

static void
vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
{
	vm_page_t m;
	int i;

	atomic_add_int(&kstacks, -1);
	pmap_qremove(ks, pages);
	VM_OBJECT_WLOCK(ksobj);
	for (i = 0; i < pages; i++) {
		m = vm_page_lookup(ksobj, i);
		if (m == NULL)
			panic("vm_thread_dispose: kstack already missing?");
		vm_page_lock(m);
		vm_page_unwire(m, PQ_NONE);
		vm_page_free(m);
		vm_page_unlock(m);
	}
	VM_OBJECT_WUNLOCK(ksobj);
	vm_object_deallocate(ksobj);
	kva_free(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
	    (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
}

/*
 * Dispose of a thread's kernel stack.
 */
void
vm_thread_dispose(struct thread *td)
{
	vm_object_t ksobj;
	vm_offset_t ks;
	struct kstack_cache_entry *ks_ce;
	int pages;

	pages = td->td_kstack_pages;
	ksobj = td->td_kstack_obj;
	ks = td->td_kstack;
	td->td_kstack = 0;
	td->td_kstack_pages = 0;
	if (pages == kstack_pages && kstacks <= kstack_cache_size) {
		ks_ce = (struct kstack_cache_entry *)ks;
		ks_ce->ksobj = ksobj;
		mtx_lock(&kstack_cache_mtx);
		ks_ce->next_ks_entry = kstack_cache;
		kstack_cache = ks_ce;
		mtx_unlock(&kstack_cache_mtx);
		return;
	}
	vm_thread_stack_dispose(ksobj, ks, pages);
}

static void
vm_thread_stack_lowmem(void *nulll)
{
	struct kstack_cache_entry *ks_ce, *ks_ce1;

	mtx_lock(&kstack_cache_mtx);
	ks_ce = kstack_cache;
	kstack_cache = NULL;
	mtx_unlock(&kstack_cache_mtx);

	while (ks_ce != NULL) {
		ks_ce1 = ks_ce;
		ks_ce = ks_ce->next_ks_entry;

		vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1,
		    kstack_pages);
	}
}

static void
kstack_cache_init(void *nulll)
{

	EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL,
	    EVENTHANDLER_PRI_ANY);
}

SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);

#ifdef KSTACK_USAGE_PROF
/*
 * Track maximum stack used by a thread in kernel.
 */
static int max_kstack_used;

SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
    &max_kstack_used, 0,
    "Maxiumum stack depth used by a thread in kernel");

void
intr_prof_stack_use(struct thread *td, struct trapframe *frame)
{
	vm_offset_t stack_top;
	vm_offset_t current;
	int used, prev_used;

	/*
	 * Testing for interrupted kernel mode isn't strictly
	 * needed. It optimizes the execution, since interrupts from
	 * usermode will have only the trap frame on the stack.
	 */
	if (TRAPF_USERMODE(frame))
		return;

	stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
	current = (vm_offset_t)(uintptr_t)&stack_top;

	/*
	 * Try to detect if interrupt is using kernel thread stack.
	 * Hardware could use a dedicated stack for interrupt handling.
	 */
	if (stack_top <= current || current < td->td_kstack)
		return;

	used = stack_top - current;
	for (;;) {
		prev_used = max_kstack_used;
		if (prev_used >= used)
			break;
		if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
			break;
	}
}
#endif /* KSTACK_USAGE_PROF */

/*
 * Implement fork's actions on an address space.
 * Here we arrange for the address space to be copied or referenced,
 * allocate a user struct (pcb and kernel stack), then call the
 * machine-dependent layer to fill those in and make the new process
 * ready to run.  The new process is set up so that it returns directly
 * to user mode to avoid stack copying and relocation problems.
 */
int
vm_forkproc(struct thread *td, struct proc *p2, struct thread *td2,
    struct vmspace *vm2, int flags)
{
	struct proc *p1 = td->td_proc;
	int error;

	if ((flags & RFPROC) == 0) {
		/*
		 * Divorce the memory, if it is shared, essentially
		 * this changes shared memory amongst threads, into
		 * COW locally.
		 */
		if ((flags & RFMEM) == 0) {
			if (p1->p_vmspace->vm_refcnt > 1) {
				error = vmspace_unshare(p1);
				if (error)
					return (error);
			}
		}
		cpu_fork(td, p2, td2, flags);
		return (0);
	}

	if (flags & RFMEM) {
		p2->p_vmspace = p1->p_vmspace;
		atomic_add_int(&p1->p_vmspace->vm_refcnt, 1);
	}

	while (vm_page_count_severe()) {
		VM_WAIT;
	}

	if ((flags & RFMEM) == 0) {
		p2->p_vmspace = vm2;
		if (p1->p_vmspace->vm_shm)
			shmfork(p1, p2);
	}

	/*
	 * cpu_fork will copy and update the pcb, set up the kernel stack,
	 * and make the child ready to run.
	 */
	cpu_fork(td, p2, td2, flags);
	return (0);
}

/*
 * Called after process has been wait(2)'ed upon and is being reaped.
 * The idea is to reclaim resources that we could not reclaim while
 * the process was still executing.
 */
void
vm_waitproc(p)
	struct proc *p;
{

	vmspace_exitfree(p);		/* and clean-out the vmspace */
}

void
kick_proc0(void)
{

	wakeup(&proc0);
}