tcp: fix ISN generator to increment based on time again

[unleashed.git] / kernel / vm / seg_kp.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*      All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*
 * segkp is a segment driver that administers the allocation and deallocation
 * of pageable variable size chunks of kernel virtual address space. Each
 * allocated resource is page-aligned.
 *
 * The user may specify whether the resource should be initialized to 0,
 * include a redzone, or locked in memory.
 */

#include <sys/types.h>
#include <sys/t_lock.h>
#include <sys/thread.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/mman.h>
#include <sys/vnode.h>
#include <sys/cmn_err.h>
#include <sys/swap.h>
#include <sys/tuneable.h>
#include <sys/kmem.h>
#include <sys/vmem.h>
#include <sys/cred.h>
#include <sys/dumphdr.h>
#include <sys/debug.h>
#include <sys/vtrace.h>
#include <sys/stack.h>
#include <sys/atomic.h>
#include <sys/archsystm.h>
#include <sys/lgrp.h>

#include <vm/as.h>
#include <vm/seg.h>
#include <vm/seg_kp.h>
#include <vm/seg_kmem.h>
#include <vm/anon.h>
#include <vm/page.h>
#include <vm/hat.h>
#include <sys/bitmap.h>

/*
 * Private seg op routines
 */
static void     segkp_badop(void);
static void     segkp_dump(struct seg *seg);
static int      segkp_checkprot(struct seg *seg, caddr_t addr, size_t len,
                        uint_t prot);
static int      segkp_kluster(struct seg *seg, caddr_t addr, ssize_t delta);
static int      segkp_pagelock(struct seg *seg, caddr_t addr, size_t len,
                        struct page ***page, enum lock_type type,
                        enum seg_rw rw);
static void     segkp_insert(struct seg *seg, struct segkp_data *kpd);
static void     segkp_delete(struct seg *seg, struct segkp_data *kpd);
static caddr_t  segkp_get_internal(struct seg *seg, size_t len, uint_t flags,
                        struct segkp_data **tkpd, struct anon_map *amp);
static void     segkp_release_internal(struct seg *seg,
                        struct segkp_data *kpd, size_t len);
static int      segkp_unlock(struct hat *hat, struct seg *seg, caddr_t vaddr,
                        size_t len, struct segkp_data *kpd, uint_t flags);
static int      segkp_load(struct hat *hat, struct seg *seg, caddr_t vaddr,
                        size_t len, struct segkp_data *kpd, uint_t flags);
static struct   segkp_data *segkp_find(struct seg *seg, caddr_t vaddr);

/*
 * Lock used to protect the hash table(s) and caches.
 */
static kmutex_t segkp_lock;

/*
 * The segkp caches
 */
static struct segkp_cache segkp_cache[SEGKP_MAX_CACHE];

#define SEGKP_BADOP(t)  (t(*)())segkp_badop

/*
 * When there are fewer than red_minavail bytes left on the stack,
 * segkp_map_red() will map in the redzone (if called).  5000 seems
 * to work reasonably well...
 */
long            red_minavail = 5000;

/*
 * will be set to 1 for 32 bit x86 systems only, in startup.c
 */
int     segkp_fromheap = 0;
ulong_t *segkp_bitmap;

/*
 * If segkp_map_red() is called with the redzone already mapped and
 * with less than RED_DEEP_THRESHOLD bytes available on the stack,
 * then the stack situation has become quite serious;  if much more stack
 * is consumed, we have the potential of scrogging the next thread/LWP
 * structure.  To help debug the "can't happen" panics which may
 * result from this condition, we record hrestime and the calling thread
 * in red_deep_hires and red_deep_thread respectively.
 */
#define RED_DEEP_THRESHOLD      2000

hrtime_t        red_deep_hires;
kthread_t       *red_deep_thread;

uint32_t        red_nmapped;
uint32_t        red_closest = UINT_MAX;
uint32_t        red_ndoubles;

pgcnt_t anon_segkp_pages_locked;        /* See vm/anon.h */
pgcnt_t anon_segkp_pages_resv;          /* anon reserved by seg_kp */

static const struct seg_ops segkp_ops = {
        .dup            = SEGKP_BADOP(int),
        .unmap          = SEGKP_BADOP(int),
        .free           = SEGKP_BADOP(void),
        .fault          = segkp_fault,
        .faulta         = SEGKP_BADOP(faultcode_t),
        .setprot        = SEGKP_BADOP(int),
        .checkprot      = segkp_checkprot,
        .kluster        = segkp_kluster,
        .sync           = SEGKP_BADOP(int),
        .incore         = SEGKP_BADOP(size_t),
        .lockop         = SEGKP_BADOP(int),
        .getprot        = SEGKP_BADOP(int),
        .getoffset      = SEGKP_BADOP(uoff_t),
        .gettype        = SEGKP_BADOP(int),
        .getvp          = SEGKP_BADOP(int),
        .advise         = SEGKP_BADOP(int),
        .dump           = segkp_dump,
        .pagelock       = segkp_pagelock,
        .setpagesize    = SEGKP_BADOP(int),
};


static void
segkp_badop(void)
{
        panic("segkp_badop");
        /*NOTREACHED*/
}

static void segkpinit_mem_config(struct seg *);

static uint32_t segkp_indel;

/*
 * Allocate the segment specific private data struct and fill it in
 * with the per kp segment mutex, anon ptr. array and hash table.
 */
int
segkp_create(struct seg *seg)
{
        struct segkp_segdata *kpsd;
        size_t  np;

        ASSERT(seg != NULL && seg->s_as == &kas);
        ASSERT(RW_WRITE_HELD(&seg->s_as->a_lock));

        if (seg->s_size & PAGEOFFSET) {
                panic("Bad segkp size");
                /*NOTREACHED*/
        }

        kpsd = kmem_zalloc(sizeof (struct segkp_segdata), KM_SLEEP);

        /*
         * Allocate the virtual memory for segkp and initialize it
         */
        if (segkp_fromheap) {
                np = btop(kvseg.s_size);
                segkp_bitmap = kmem_zalloc(BT_SIZEOFMAP(np), KM_SLEEP);
                kpsd->kpsd_arena = vmem_create("segkp", NULL, 0, PAGESIZE,
                    vmem_alloc, vmem_free, heap_arena, 5 * PAGESIZE, VM_SLEEP);
        } else {
                segkp_bitmap = NULL;
                np = btop(seg->s_size);
                kpsd->kpsd_arena = vmem_create("segkp", seg->s_base,
                    seg->s_size, PAGESIZE, NULL, NULL, NULL, 5 * PAGESIZE,
                    VM_SLEEP);
        }

        kpsd->kpsd_anon = anon_create(np, ANON_SLEEP | ANON_ALLOC_FORCE);

        kpsd->kpsd_hash = kmem_zalloc(SEGKP_HASHSZ * sizeof (struct segkp *),
            KM_SLEEP);
        seg->s_data = (void *)kpsd;
        seg->s_ops = &segkp_ops;
        segkpinit_mem_config(seg);
        return (0);
}


/*
 * Find a free 'freelist' and initialize it with the appropriate attributes
 */
void *
segkp_cache_init(struct seg *seg, int maxsize, size_t len, uint_t flags)
{
        int i;

        if ((flags & KPD_NO_ANON) && !(flags & KPD_LOCKED))
                return ((void *)-1);

        mutex_enter(&segkp_lock);
        for (i = 0; i < SEGKP_MAX_CACHE; i++) {
                if (segkp_cache[i].kpf_inuse)
                        continue;
                segkp_cache[i].kpf_inuse = 1;
                segkp_cache[i].kpf_max = maxsize;
                segkp_cache[i].kpf_flags = flags;
                segkp_cache[i].kpf_seg = seg;
                segkp_cache[i].kpf_len = len;
                mutex_exit(&segkp_lock);
                return ((void *)(uintptr_t)i);
        }
        mutex_exit(&segkp_lock);
        return ((void *)-1);
}

/*
 * Free all the cache resources.
 */
void
segkp_cache_free(void)
{
        struct segkp_data *kpd;
        struct seg *seg;
        int i;

        mutex_enter(&segkp_lock);
        for (i = 0; i < SEGKP_MAX_CACHE; i++) {
                if (!segkp_cache[i].kpf_inuse)
                        continue;
                /*
                 * Disconnect the freelist and process each element
                 */
                kpd = segkp_cache[i].kpf_list;
                seg = segkp_cache[i].kpf_seg;
                segkp_cache[i].kpf_list = NULL;
                segkp_cache[i].kpf_count = 0;
                mutex_exit(&segkp_lock);

                while (kpd != NULL) {
                        struct segkp_data *next;

                        next = kpd->kp_next;
                        segkp_release_internal(seg, kpd, kpd->kp_len);
                        kpd = next;
                }
                mutex_enter(&segkp_lock);
        }
        mutex_exit(&segkp_lock);
}

/*
 * There are 2 entries into segkp_get_internal. The first includes a cookie
 * used to access a pool of cached segkp resources. The second does not
 * use the cache.
 */
caddr_t
segkp_get(struct seg *seg, size_t len, uint_t flags)
{
        struct segkp_data *kpd = NULL;

        if (segkp_get_internal(seg, len, flags, &kpd, NULL) != NULL) {
                kpd->kp_cookie = -1;
                return (stom(kpd->kp_base, flags));
        }
        return (NULL);
}

/*
 * Return a 'cached' segkp address
 */
caddr_t
segkp_cache_get(void *cookie)
{
        struct segkp_cache *freelist = NULL;
        struct segkp_data *kpd = NULL;
        int index = (int)(uintptr_t)cookie;
        struct seg *seg;
        size_t len;
        uint_t flags;

        if (index < 0 || index >= SEGKP_MAX_CACHE)
                return (NULL);
        freelist = &segkp_cache[index];

        mutex_enter(&segkp_lock);
        seg = freelist->kpf_seg;
        flags = freelist->kpf_flags;
        if (freelist->kpf_list != NULL) {
                kpd = freelist->kpf_list;
                freelist->kpf_list = kpd->kp_next;
                freelist->kpf_count--;
                mutex_exit(&segkp_lock);
                kpd->kp_next = NULL;
                segkp_insert(seg, kpd);
                return (stom(kpd->kp_base, flags));
        }
        len = freelist->kpf_len;
        mutex_exit(&segkp_lock);
        if (segkp_get_internal(seg, len, flags, &kpd, NULL) != NULL) {
                kpd->kp_cookie = index;
                return (stom(kpd->kp_base, flags));
        }
        return (NULL);
}

caddr_t
segkp_get_withanonmap(
        struct seg *seg,
        size_t len,
        uint_t flags,
        struct anon_map *amp)
{
        struct segkp_data *kpd = NULL;

        ASSERT(amp != NULL);
        flags |= KPD_HASAMP;
        if (segkp_get_internal(seg, len, flags, &kpd, amp) != NULL) {
                kpd->kp_cookie = -1;
                return (stom(kpd->kp_base, flags));
        }
        return (NULL);
}

/*
 * This does the real work of segkp allocation.
 * Return to client base addr. len must be page-aligned. A null value is
 * returned if there are no more vm resources (e.g. pages, swap). The len
 * and base recorded in the private data structure include the redzone
 * and the redzone length (if applicable). If the user requests a redzone
 * either the first or last page is left unmapped depending whether stacks
 * grow to low or high memory.
 *
 * The client may also specify a no-wait flag. If that is set then the
 * request will choose a non-blocking path when requesting resources.
 * The default is make the client wait.
 */
static caddr_t
segkp_get_internal(
        struct seg *seg,
        size_t len,
        uint_t flags,
        struct segkp_data **tkpd,
        struct anon_map *amp)
{
        struct segkp_segdata    *kpsd = (struct segkp_segdata *)seg->s_data;
        struct segkp_data       *kpd;
        caddr_t vbase = NULL;   /* always first virtual, may not be mapped */
        pgcnt_t np = 0;         /* number of pages in the resource */
        pgcnt_t segkpindex;
        long i;
        caddr_t va;
        pgcnt_t pages = 0;
        ulong_t anon_idx = 0;
        int kmflag = (flags & KPD_NOWAIT) ? KM_NOSLEEP : KM_SLEEP;
        caddr_t s_base = (segkp_fromheap) ? kvseg.s_base : seg->s_base;

        if (len & PAGEOFFSET) {
                panic("segkp_get: len is not page-aligned");
                /*NOTREACHED*/
        }

        ASSERT(((flags & KPD_HASAMP) == 0) == (amp == NULL));

        /* Only allow KPD_NO_ANON if we are going to lock it down */
        if ((flags & (KPD_LOCKED|KPD_NO_ANON)) == KPD_NO_ANON)
                return (NULL);

        if ((kpd = kmem_zalloc(sizeof (struct segkp_data), kmflag)) == NULL)
                return (NULL);
        /*
         * Fix up the len to reflect the REDZONE if applicable
         */
        if (flags & KPD_HASREDZONE)
                len += PAGESIZE;
        np = btop(len);

        vbase = vmem_alloc(SEGKP_VMEM(seg), len, kmflag | VM_BESTFIT);
        if (vbase == NULL) {
                kmem_free(kpd, sizeof (struct segkp_data));
                return (NULL);
        }

        /* If locking, reserve physical memory */
        if (flags & KPD_LOCKED) {
                pages = btop(SEGKP_MAPLEN(len, flags));
                if (page_resv(pages, kmflag) == 0) {
                        vmem_free(SEGKP_VMEM(seg), vbase, len);
                        kmem_free(kpd, sizeof (struct segkp_data));
                        return (NULL);
                }
                if ((flags & KPD_NO_ANON) == 0)
                        atomic_add_long(&anon_segkp_pages_locked, pages);
        }

        /*
         * Reserve sufficient swap space for this vm resource.  We'll
         * actually allocate it in the loop below, but reserving it
         * here allows us to back out more gracefully than if we
         * had an allocation failure in the body of the loop.
         *
         * Note that we don't need swap space for the red zone page.
         */
        if (amp != NULL) {
                /*
                 * The swap reservation has been done, if required, and the
                 * anon_hdr is separate.
                 */
                anon_idx = 0;
                kpd->kp_anon_idx = anon_idx;
                kpd->kp_anon = amp->ahp;
        } else if ((flags & KPD_NO_ANON) == 0) {
                if (anon_resv_zone(SEGKP_MAPLEN(len, flags), NULL) == 0) {
                        if (flags & KPD_LOCKED) {
                                atomic_add_long(&anon_segkp_pages_locked,
                                    -pages);
                                page_unresv(pages);
                        }
                        vmem_free(SEGKP_VMEM(seg), vbase, len);
                        kmem_free(kpd, sizeof (struct segkp_data));
                        return (NULL);
                }
                atomic_add_long(&anon_segkp_pages_resv,
                    btop(SEGKP_MAPLEN(len, flags)));
                anon_idx = ((uintptr_t)(vbase - s_base)) >> PAGESHIFT;
                kpd->kp_anon_idx = anon_idx;
                kpd->kp_anon = kpsd->kpsd_anon;
        } else {
                kpd->kp_anon = NULL;
                kpd->kp_anon_idx = 0;
        }

        /*
         * Allocate page and anon resources for the virtual address range
         * except the redzone
         */
        if (segkp_fromheap)
                segkpindex = btop((uintptr_t)(vbase - kvseg.s_base));
        for (i = 0, va = vbase; i < np; i++, va += PAGESIZE) {
                page_t          *pl[2];
                struct vnode    *vp;
                anoff_t         off;
                int             err;
                page_t          *pp = NULL;

                /*
                 * Mark this page to be a segkp page in the bitmap.
                 */
                if (segkp_fromheap) {
                        BT_ATOMIC_SET(segkp_bitmap, segkpindex);
                        segkpindex++;
                }

                /*
                 * If this page is the red zone page, we don't need swap
                 * space for it.  Note that we skip over the code that
                 * establishes MMU mappings, so that the page remains
                 * invalid.
                 */
                if ((flags & KPD_HASREDZONE) && KPD_REDZONE(kpd) == i)
                        continue;

                if (kpd->kp_anon != NULL) {
                        struct anon *ap;

                        ASSERT(anon_get_ptr(kpd->kp_anon, anon_idx + i)
                            == NULL);
                        /*
                         * Determine the "vp" and "off" of the anon slot.
                         */
                        ap = anon_alloc(NULL, 0);
                        if (amp != NULL)
                                ANON_LOCK_ENTER(&amp->a_rwlock, RW_WRITER);
                        (void) anon_set_ptr(kpd->kp_anon, anon_idx + i,
                            ap, ANON_SLEEP);
                        if (amp != NULL)
                                ANON_LOCK_EXIT(&amp->a_rwlock);
                        swap_xlate(ap, &vp, &off);

                        /*
                         * Create a page with the specified identity.  The
                         * page is returned with the "shared" lock held.
                         */
                        err = fop_getpage(vp, (offset_t)off, PAGESIZE,
                            NULL, pl, PAGESIZE, seg, va, S_CREATE,
                            kcred, NULL);
                        if (err) {
                                /*
                                 * XXX - This should not fail.
                                 */
                                panic("segkp_get: no pages");
                                /*NOTREACHED*/
                        }
                        pp = pl[0];
                } else {
                        ASSERT(page_exists(&kvp,
                            (uoff_t)(uintptr_t)va) == NULL);

                        if ((pp = page_create_va(&kvp.v_object,
                            (uoff_t)(uintptr_t)va, PAGESIZE,
                            (flags & KPD_NOWAIT ? 0 : PG_WAIT) | PG_EXCL |
                            PG_NORELOC, seg, va)) == NULL) {
                                /*
                                 * Legitimize resource; then destroy it.
                                 * Easier than trying to unwind here.
                                 */
                                kpd->kp_flags = flags;
                                kpd->kp_base = vbase;
                                kpd->kp_len = len;
                                segkp_release_internal(seg, kpd, va - vbase);
                                return (NULL);
                        }
                        page_io_unlock(pp);
                }

                if (flags & KPD_ZERO)
                        pagezero(pp, 0, PAGESIZE);

                /*
                 * Load and lock an MMU translation for the page.
                 */
                hat_memload(seg->s_as->a_hat, va, pp, (PROT_READ|PROT_WRITE),
                    ((flags & KPD_LOCKED) ? HAT_LOAD_LOCK : HAT_LOAD));

                /*
                 * Now, release lock on the page.
                 */
                if (flags & KPD_LOCKED) {
                        /*
                         * Indicate to page_retire framework that this
                         * page can only be retired when it is freed.
                         */
                        PP_SETRAF(pp);
                        page_downgrade(pp);
                } else
                        page_unlock(pp);
        }

        kpd->kp_flags = flags;
        kpd->kp_base = vbase;
        kpd->kp_len = len;
        segkp_insert(seg, kpd);
        *tkpd = kpd;
        return (stom(kpd->kp_base, flags));
}

/*
 * Release the resource to cache if the pool(designate by the cookie)
 * has less than the maximum allowable. If inserted in cache,
 * segkp_delete insures element is taken off of active list.
 */
void
segkp_release(struct seg *seg, caddr_t vaddr)
{
        struct segkp_cache *freelist;
        struct segkp_data *kpd = NULL;

        if ((kpd = segkp_find(seg, vaddr)) == NULL) {
                panic("segkp_release: null kpd");
                /*NOTREACHED*/
        }

        if (kpd->kp_cookie != -1) {
                freelist = &segkp_cache[kpd->kp_cookie];
                mutex_enter(&segkp_lock);
                if (!segkp_indel && freelist->kpf_count < freelist->kpf_max) {
                        segkp_delete(seg, kpd);
                        kpd->kp_next = freelist->kpf_list;
                        freelist->kpf_list = kpd;
                        freelist->kpf_count++;
                        mutex_exit(&segkp_lock);
                        return;
                } else {
                        mutex_exit(&segkp_lock);
                        kpd->kp_cookie = -1;
                }
        }
        segkp_release_internal(seg, kpd, kpd->kp_len);
}

/*
 * Free the entire resource. segkp_unlock gets called with the start of the
 * mapped portion of the resource. The length is the size of the mapped
 * portion
 */
static void
segkp_release_internal(struct seg *seg, struct segkp_data *kpd, size_t len)
{
        caddr_t         va;
        long            i;
        long            redzone;
        size_t          np;
        page_t          *pp;
        struct vnode    *vp;
        anoff_t         off;
        struct anon     *ap;
        pgcnt_t         segkpindex;

        ASSERT(kpd != NULL);
        ASSERT((kpd->kp_flags & KPD_HASAMP) == 0 || kpd->kp_cookie == -1);
        np = btop(len);

        /* Remove from active hash list */
        if (kpd->kp_cookie == -1) {
                mutex_enter(&segkp_lock);
                segkp_delete(seg, kpd);
                mutex_exit(&segkp_lock);
        }

        /*
         * Precompute redzone page index.
         */
        redzone = -1;
        if (kpd->kp_flags & KPD_HASREDZONE)
                redzone = KPD_REDZONE(kpd);


        va = kpd->kp_base;

        hat_unload(seg->s_as->a_hat, va, (np << PAGESHIFT),
            ((kpd->kp_flags & KPD_LOCKED) ? HAT_UNLOAD_UNLOCK : HAT_UNLOAD));
        /*
         * Free up those anon resources that are quiescent.
         */
        if (segkp_fromheap)
                segkpindex = btop((uintptr_t)(va - kvseg.s_base));
        for (i = 0; i < np; i++, va += PAGESIZE) {

                /*
                 * Clear the bit for this page from the bitmap.
                 */
                if (segkp_fromheap) {
                        BT_ATOMIC_CLEAR(segkp_bitmap, segkpindex);
                        segkpindex++;
                }

                if (i == redzone)
                        continue;
                if (kpd->kp_anon) {
                        /*
                         * Free up anon resources and destroy the
                         * associated pages.
                         *
                         * Release the lock if there is one. Have to get the
                         * page to do this, unfortunately.
                         */
                        if (kpd->kp_flags & KPD_LOCKED) {
                                ap = anon_get_ptr(kpd->kp_anon,
                                    kpd->kp_anon_idx + i);
                                swap_xlate(ap, &vp, &off);
                                /* Find the shared-locked page. */
                                pp = page_find(&vp->v_object, (uoff_t)off);
                                if (pp == NULL) {
                                        panic("segkp_release: "
                                            "kp_anon: no page to unlock ");
                                        /*NOTREACHED*/
                                }
                                if (PP_ISRAF(pp))
                                        PP_CLRRAF(pp);

                                page_unlock(pp);
                        }
                        if ((kpd->kp_flags & KPD_HASAMP) == 0) {
                                anon_free(kpd->kp_anon, kpd->kp_anon_idx + i,
                                    PAGESIZE);
                                anon_unresv_zone(PAGESIZE, NULL);
                                atomic_dec_ulong(&anon_segkp_pages_resv);
                        }
                } else {
                        if (kpd->kp_flags & KPD_LOCKED) {
                                pp = page_find(&kvp.v_object,
                                               (uoff_t)(uintptr_t)va);
                                if (pp == NULL) {
                                        panic("segkp_release: "
                                            "no page to unlock");
                                        /*NOTREACHED*/
                                }
                                if (PP_ISRAF(pp))
                                        PP_CLRRAF(pp);
                                /*
                                 * We should just upgrade the lock here
                                 * but there is no upgrade that waits.
                                 */
                                page_unlock(pp);
                        }
                        pp = page_lookup(&(&kvp)->v_object,
                                         (uoff_t)(uintptr_t)va, SE_EXCL);
                        if (pp != NULL)
                                page_destroy(pp, 0);
                }
        }

        /* If locked, release physical memory reservation */
        if (kpd->kp_flags & KPD_LOCKED) {
                pgcnt_t pages = btop(SEGKP_MAPLEN(kpd->kp_len, kpd->kp_flags));
                if ((kpd->kp_flags & KPD_NO_ANON) == 0)
                        atomic_add_long(&anon_segkp_pages_locked, -pages);
                page_unresv(pages);
        }

        vmem_free(SEGKP_VMEM(seg), kpd->kp_base, kpd->kp_len);
        kmem_free(kpd, sizeof (struct segkp_data));
}

/*
 * segkp_map_red() will check the current frame pointer against the
 * stack base.  If the amount of stack remaining is questionable
 * (less than red_minavail), then segkp_map_red() will map in the redzone
 * and return 1.  Otherwise, it will return 0.  segkp_map_red() can
 * _only_ be called when it is safe to sleep on page_create_va().
 *
 * It is up to the caller to remember whether segkp_map_red() successfully
 * mapped the redzone, and, if so, to call segkp_unmap_red() at a later
 * time.
 *
 * Currently, this routine is only called from pagefault() (which necessarily
 * satisfies the above conditions).
 */
#if defined(STACK_GROWTH_DOWN)
int
segkp_map_red(void)
{
        uintptr_t fp = STACK_BIAS + (uintptr_t)getfp();
#ifndef _LP64
        caddr_t stkbase;
#endif

        /*
         * Optimize for the common case where we simply return.
         */
        if ((curthread->t_red_pp == NULL) &&
            (fp - (uintptr_t)curthread->t_stkbase >= red_minavail))
                return (0);

#if defined(_LP64)
        /*
         * XXX  We probably need something better than this.
         */
        panic("kernel stack overflow");
        /*NOTREACHED*/
#else /* _LP64 */
        if (curthread->t_red_pp == NULL) {
                page_t *red_pp;
                struct seg kseg;

                caddr_t red_va = (caddr_t)
                    (((uintptr_t)curthread->t_stkbase & (uintptr_t)PAGEMASK) -
                    PAGESIZE);

                ASSERT(page_exists(&kvp, (uoff_t)(uintptr_t)red_va) ==
                    NULL);

                /*
                 * Allocate the physical for the red page.
                 */
                /*
                 * No PG_NORELOC here to avoid waits. Unlikely to get
                 * a relocate happening in the short time the page exists
                 * and it will be OK anyway.
                 */

                kseg.s_as = &kas;
                red_pp = page_create_va(&kvp.v_object, (uoff_t)(uintptr_t)red_va,
                    PAGESIZE, PG_WAIT | PG_EXCL, &kseg, red_va);
                ASSERT(red_pp != NULL);

                /*
                 * So we now have a page to jam into the redzone...
                 */
                page_io_unlock(red_pp);

                hat_memload(kas.a_hat, red_va, red_pp,
                    (PROT_READ|PROT_WRITE), HAT_LOAD_LOCK);
                page_downgrade(red_pp);

                /*
                 * The page is left SE_SHARED locked so we can hold on to
                 * the page_t pointer.
                 */
                curthread->t_red_pp = red_pp;

                atomic_inc_32(&red_nmapped);
                while (fp - (uintptr_t)curthread->t_stkbase < red_closest) {
                        (void) atomic_cas_32(&red_closest, red_closest,
                            (uint32_t)(fp - (uintptr_t)curthread->t_stkbase));
                }
                return (1);
        }

        stkbase = (caddr_t)(((uintptr_t)curthread->t_stkbase &
            (uintptr_t)PAGEMASK) - PAGESIZE);

        atomic_inc_32(&red_ndoubles);

        if (fp - (uintptr_t)stkbase < RED_DEEP_THRESHOLD) {
                /*
                 * Oh boy.  We're already deep within the mapped-in
                 * redzone page, and the caller is trying to prepare
                 * for a deep stack run.  We're running without a
                 * redzone right now:  if the caller plows off the
                 * end of the stack, it'll plow another thread or
                 * LWP structure.  That situation could result in
                 * a very hard-to-debug panic, so, in the spirit of
                 * recording the name of one's killer in one's own
                 * blood, we're going to record hrestime and the calling
                 * thread.
                 */
                red_deep_hires = hrestime.tv_nsec;
                red_deep_thread = curthread;
        }

        /*
         * If this is a DEBUG kernel, and we've run too deep for comfort, toss.
         */
        ASSERT(fp - (uintptr_t)stkbase >= RED_DEEP_THRESHOLD);
        return (0);
#endif /* _LP64 */
}

void
segkp_unmap_red(void)
{
        page_t *pp;
        caddr_t red_va = (caddr_t)(((uintptr_t)curthread->t_stkbase &
            (uintptr_t)PAGEMASK) - PAGESIZE);

        ASSERT(curthread->t_red_pp != NULL);

        /*
         * Because we locked the mapping down, we can't simply rely
         * on page_destroy() to clean everything up;  we need to call
         * hat_unload() to explicitly unlock the mapping resources.
         */
        hat_unload(kas.a_hat, red_va, PAGESIZE, HAT_UNLOAD_UNLOCK);

        pp = curthread->t_red_pp;

        ASSERT(pp == page_find(&kvp.v_object, (uoff_t)(uintptr_t)red_va));

        /*
         * Need to upgrade the SE_SHARED lock to SE_EXCL.
         */
        if (!page_tryupgrade(pp)) {
                /*
                 * As there is now wait for upgrade, release the
                 * SE_SHARED lock and wait for SE_EXCL.
                 */
                page_unlock(pp);
                pp = page_lookup(&(&kvp)->v_object,
                                 (uoff_t)(uintptr_t)red_va, SE_EXCL);
                /* pp may be NULL here, hence the test below */
        }

        /*
         * Destroy the page, with dontfree set to zero (i.e. free it).
         */
        if (pp != NULL)
                page_destroy(pp, 0);
        curthread->t_red_pp = NULL;
}
#else
#error Red stacks only supported with downwards stack growth.
#endif

/*
 * Handle a fault on an address corresponding to one of the
 * resources in the segkp segment.
 */
faultcode_t
segkp_fault(
        struct hat      *hat,
        struct seg      *seg,
        caddr_t         vaddr,
        size_t          len,
        enum fault_type type,
        enum seg_rw rw)
{
        struct segkp_data       *kpd = NULL;
        int                     err;

        ASSERT(seg->s_as == &kas && RW_READ_HELD(&seg->s_as->a_lock));

        /*
         * Sanity checks.
         */
        if (type == F_PROT) {
                panic("segkp_fault: unexpected F_PROT fault");
                /*NOTREACHED*/
        }

        if ((kpd = segkp_find(seg, vaddr)) == NULL)
                return (FC_NOMAP);

        mutex_enter(&kpd->kp_lock);

        if (type == F_SOFTLOCK) {
                ASSERT(!(kpd->kp_flags & KPD_LOCKED));
                /*
                 * The F_SOFTLOCK case has more stringent
                 * range requirements: the given range must exactly coincide
                 * with the resource's mapped portion. Note reference to
                 * redzone is handled since vaddr would not equal base
                 */
                if (vaddr != stom(kpd->kp_base, kpd->kp_flags) ||
                    len != SEGKP_MAPLEN(kpd->kp_len, kpd->kp_flags)) {
                        mutex_exit(&kpd->kp_lock);
                        return (FC_MAKE_ERR(EFAULT));
                }

                if ((err = segkp_load(hat, seg, vaddr, len, kpd, KPD_LOCKED))) {
                        mutex_exit(&kpd->kp_lock);
                        return (FC_MAKE_ERR(err));
                }
                kpd->kp_flags |= KPD_LOCKED;
                mutex_exit(&kpd->kp_lock);
                return (0);
        }

        if (type == F_INVAL) {
                ASSERT(!(kpd->kp_flags & KPD_NO_ANON));

                /*
                 * Check if we touched the redzone. Somewhat optimistic
                 * here if we are touching the redzone of our own stack
                 * since we wouldn't have a stack to get this far...
                 */
                if ((kpd->kp_flags & KPD_HASREDZONE) &&
                    btop((uintptr_t)(vaddr - kpd->kp_base)) == KPD_REDZONE(kpd))
                        panic("segkp_fault: accessing redzone");

                /*
                 * This fault may occur while the page is being F_SOFTLOCK'ed.
                 * Return since a 2nd segkp_load is unnecessary and also would
                 * result in the page being locked twice and eventually
                 * hang the thread_reaper thread.
                 */
                if (kpd->kp_flags & KPD_LOCKED) {
                        mutex_exit(&kpd->kp_lock);
                        return (0);
                }

                err = segkp_load(hat, seg, vaddr, len, kpd, kpd->kp_flags);
                mutex_exit(&kpd->kp_lock);
                return (err ? FC_MAKE_ERR(err) : 0);
        }

        if (type == F_SOFTUNLOCK) {
                uint_t  flags;

                /*
                 * Make sure the addr is LOCKED and it has anon backing
                 * before unlocking
                 */
                if ((kpd->kp_flags & (KPD_LOCKED|KPD_NO_ANON)) != KPD_LOCKED) {
                        panic("segkp_fault: bad unlock");
                        /*NOTREACHED*/
                }

                if (vaddr != stom(kpd->kp_base, kpd->kp_flags) ||
                    len != SEGKP_MAPLEN(kpd->kp_len, kpd->kp_flags)) {
                        panic("segkp_fault: bad range");
                        /*NOTREACHED*/
                }

                if (rw == S_WRITE)
                        flags = kpd->kp_flags | KPD_WRITEDIRTY;
                else
                        flags = kpd->kp_flags;
                err = segkp_unlock(hat, seg, vaddr, len, kpd, flags);
                kpd->kp_flags &= ~KPD_LOCKED;
                mutex_exit(&kpd->kp_lock);
                return (err ? FC_MAKE_ERR(err) : 0);
        }
        mutex_exit(&kpd->kp_lock);
        panic("segkp_fault: bogus fault type: %d\n", type);
        /*NOTREACHED*/
}

/*
 * Check that the given protections suffice over the range specified by
 * vaddr and len.  For this segment type, the only issue is whether or
 * not the range lies completely within the mapped part of an allocated
 * resource.
 */
/* ARGSUSED */
static int
segkp_checkprot(struct seg *seg, caddr_t vaddr, size_t len, uint_t prot)
{
        struct segkp_data *kpd = NULL;
        caddr_t mbase;
        size_t mlen;

        if ((kpd = segkp_find(seg, vaddr)) == NULL)
                return (EACCES);

        mutex_enter(&kpd->kp_lock);
        mbase = stom(kpd->kp_base, kpd->kp_flags);
        mlen = SEGKP_MAPLEN(kpd->kp_len, kpd->kp_flags);
        if (len > mlen || vaddr < mbase ||
            ((vaddr + len) > (mbase + mlen))) {
                mutex_exit(&kpd->kp_lock);
                return (EACCES);
        }
        mutex_exit(&kpd->kp_lock);
        return (0);
}


/*
 * Check to see if it makes sense to do kluster/read ahead to
 * addr + delta relative to the mapping at addr.  We assume here
 * that delta is a signed PAGESIZE'd multiple (which can be negative).
 *
 * For seg_u we always "approve" of this action from our standpoint.
 */
/*ARGSUSED*/
static int
segkp_kluster(struct seg *seg, caddr_t addr, ssize_t delta)
{
        return (0);
}

/*
 * Load and possibly lock intra-slot resources in the range given by
 * vaddr and len.
 */
static int
segkp_load(
        struct hat *hat,
        struct seg *seg,
        caddr_t vaddr,
        size_t len,
        struct segkp_data *kpd,
        uint_t flags)
{
        caddr_t va;
        caddr_t vlim;
        ulong_t i;
        uint_t lock;

        ASSERT(MUTEX_HELD(&kpd->kp_lock));

        len = P2ROUNDUP(len, PAGESIZE);

        /* If locking, reserve physical memory */
        if (flags & KPD_LOCKED) {
                pgcnt_t pages = btop(len);
                if ((kpd->kp_flags & KPD_NO_ANON) == 0)
                        atomic_add_long(&anon_segkp_pages_locked, pages);
                (void) page_resv(pages, KM_SLEEP);
        }

        /*
         * Loop through the pages in the given range.
         */
        va = (caddr_t)((uintptr_t)vaddr & (uintptr_t)PAGEMASK);
        vaddr = va;
        vlim = va + len;
        lock = flags & KPD_LOCKED;
        i = ((uintptr_t)(va - kpd->kp_base)) >> PAGESHIFT;
        for (; va < vlim; va += PAGESIZE, i++) {
                page_t          *pl[2]; /* second element NULL terminator */
                struct vnode    *vp;
                anoff_t         off;
                int             err;
                struct anon     *ap;

                /*
                 * Summon the page.  If it's not resident, arrange
                 * for synchronous i/o to pull it in.
                 */
                ap = anon_get_ptr(kpd->kp_anon, kpd->kp_anon_idx + i);
                swap_xlate(ap, &vp, &off);

                /*
                 * The returned page list will have exactly one entry,
                 * which is returned to us already kept.
                 */
                err = fop_getpage(vp, (offset_t)off, PAGESIZE, NULL,
                    pl, PAGESIZE, seg, va, S_READ, kcred, NULL);

                if (err) {
                        /*
                         * Back out of what we've done so far.
                         */
                        (void) segkp_unlock(hat, seg, vaddr,
                            (va - vaddr), kpd, flags);
                        return (err);
                }

                /*
                 * Load an MMU translation for the page.
                 */
                hat_memload(hat, va, pl[0], (PROT_READ|PROT_WRITE),
                    lock ? HAT_LOAD_LOCK : HAT_LOAD);

                if (!lock) {
                        /*
                         * Now, release "shared" lock on the page.
                         */
                        page_unlock(pl[0]);
                }
        }
        return (0);
}

/*
 * At the very least unload the mmu-translations and unlock the range if locked
 * Can be called with the following flag value KPD_WRITEDIRTY which specifies
 * any dirty pages should be written to disk.
 */
static int
segkp_unlock(
        struct hat *hat,
        struct seg *seg,
        caddr_t vaddr,
        size_t len,
        struct segkp_data *kpd,
        uint_t flags)
{
        caddr_t va;
        caddr_t vlim;
        ulong_t i;
        struct page *pp;
        struct vnode *vp;
        anoff_t off;
        struct anon *ap;


        ASSERT(MUTEX_HELD(&kpd->kp_lock));

        /*
         * Loop through the pages in the given range. It is assumed
         * segkp_unlock is called with page aligned base
         */
        va = vaddr;
        vlim = va + len;
        i = ((uintptr_t)(va - kpd->kp_base)) >> PAGESHIFT;
        hat_unload(hat, va, len,
            ((flags & KPD_LOCKED) ? HAT_UNLOAD_UNLOCK : HAT_UNLOAD));
        for (; va < vlim; va += PAGESIZE, i++) {
                /*
                 * Find the page associated with this part of the
                 * slot, tracking it down through its associated swap
                 * space.
                 */
                ap = anon_get_ptr(kpd->kp_anon, kpd->kp_anon_idx + i);
                swap_xlate(ap, &vp, &off);

                if (flags & KPD_LOCKED) {
                        if ((pp = page_find(&vp->v_object, off)) == NULL) {
                                if (flags & KPD_LOCKED) {
                                        panic("segkp_softunlock: missing page");
                                        /*NOTREACHED*/
                                }
                        }
                } else {
                        /*
                         * Nothing to do if the slot is not locked and the
                         * page doesn't exist.
                         */
                        if ((pp = page_lookup(&vp->v_object, off, SE_SHARED)) == NULL)
                                continue;
                }

                /*
                 * If the page doesn't have any translations, is
                 * dirty and not being shared, then push it out
                 * asynchronously and avoid waiting for the
                 * pageout daemon to do it for us.
                 *
                 * XXX - Do we really need to get the "exclusive"
                 * lock via an upgrade?
                 */
                if ((flags & KPD_WRITEDIRTY) && !hat_page_is_mapped(pp) &&
                    hat_ismod(pp) && page_tryupgrade(pp)) {
                        /*
                         * Hold the vnode before releasing the page lock to
                         * prevent it from being freed and re-used by some
                         * other thread.
                         */
                        VN_HOLD(vp);
                        page_unlock(pp);

                        /*
                         * Want most powerful credentials we can get so
                         * use kcred.
                         */
                        (void) fop_putpage(vp, (offset_t)off, PAGESIZE,
                            B_ASYNC | B_FREE, kcred, NULL);
                        VN_RELE(vp);
                } else {
                        page_unlock(pp);
                }
        }

        /* If unlocking, release physical memory */
        if (flags & KPD_LOCKED) {
                pgcnt_t pages = btopr(len);
                if ((kpd->kp_flags & KPD_NO_ANON) == 0)
                        atomic_add_long(&anon_segkp_pages_locked, -pages);
                page_unresv(pages);
        }
        return (0);
}

/*
 * Insert the kpd in the hash table.
 */
static void
segkp_insert(struct seg *seg, struct segkp_data *kpd)
{
        struct segkp_segdata *kpsd = (struct segkp_segdata *)seg->s_data;
        int index;

        /*
         * Insert the kpd based on the address that will be returned
         * via segkp_release.
         */
        index = SEGKP_HASH(stom(kpd->kp_base, kpd->kp_flags));
        mutex_enter(&segkp_lock);
        kpd->kp_next = kpsd->kpsd_hash[index];
        kpsd->kpsd_hash[index] = kpd;
        mutex_exit(&segkp_lock);
}

/*
 * Remove kpd from the hash table.
 */
static void
segkp_delete(struct seg *seg, struct segkp_data *kpd)
{
        struct segkp_segdata *kpsd = (struct segkp_segdata *)seg->s_data;
        struct segkp_data **kpp;
        int index;

        ASSERT(MUTEX_HELD(&segkp_lock));

        index = SEGKP_HASH(stom(kpd->kp_base, kpd->kp_flags));
        for (kpp = &kpsd->kpsd_hash[index];
            *kpp != NULL; kpp = &((*kpp)->kp_next)) {
                if (*kpp == kpd) {
                        *kpp = kpd->kp_next;
                        return;
                }
        }
        panic("segkp_delete: unable to find element to delete");
        /*NOTREACHED*/
}

/*
 * Find the kpd associated with a vaddr.
 *
 * Most of the callers of segkp_find will pass the vaddr that
 * hashes to the desired index, but there are cases where
 * this is not true in which case we have to (potentially) scan
 * the whole table looking for it. This should be very rare
 * (e.g. a segkp_fault(F_INVAL) on an address somewhere in the
 * middle of the segkp_data region).
 */
static struct segkp_data *
segkp_find(struct seg *seg, caddr_t vaddr)
{
        struct segkp_segdata *kpsd = (struct segkp_segdata *)seg->s_data;
        struct segkp_data *kpd;
        int     i;
        int     stop;

        i = stop = SEGKP_HASH(vaddr);
        mutex_enter(&segkp_lock);
        do {
                for (kpd = kpsd->kpsd_hash[i]; kpd != NULL;
                    kpd = kpd->kp_next) {
                        if (vaddr >= kpd->kp_base &&
                            vaddr < kpd->kp_base + kpd->kp_len) {
                                mutex_exit(&segkp_lock);
                                return (kpd);
                        }
                }
                if (--i < 0)
                        i = SEGKP_HASHSZ - 1;   /* Wrap */
        } while (i != stop);
        mutex_exit(&segkp_lock);
        return (NULL);          /* Not found */
}

/*
 * Dump out all the active segkp pages
 */
static void
segkp_dump(struct seg *seg)
{
        int i;
        struct segkp_data *kpd;
        struct segkp_segdata *kpsd = (struct segkp_segdata *)seg->s_data;

        for (i = 0; i < SEGKP_HASHSZ; i++) {
                for (kpd = kpsd->kpsd_hash[i];
                    kpd != NULL; kpd = kpd->kp_next) {
                        pfn_t pfn;
                        caddr_t addr;
                        caddr_t eaddr;

                        addr = kpd->kp_base;
                        eaddr = addr + kpd->kp_len;
                        while (addr < eaddr) {
                                ASSERT(seg->s_as == &kas);
                                pfn = hat_getpfnum(seg->s_as->a_hat, addr);
                                if (pfn != PFN_INVALID)
                                        dump_addpage(seg->s_as, addr, pfn);
                                addr += PAGESIZE;
                                dump_timeleft = dump_timeout;
                        }
                }
        }
}

/*ARGSUSED*/
static int
segkp_pagelock(struct seg *seg, caddr_t addr, size_t len,
    struct page ***ppp, enum lock_type type, enum seg_rw rw)
{
        return (ENOTSUP);
}

#include <sys/mem_config.h>

/*ARGSUSED*/
static void
segkp_mem_config_post_add(void *arg, pgcnt_t delta_pages)
{}

/*
 * During memory delete, turn off caches so that pages are not held.
 * A better solution may be to unlock the pages while they are
 * in the cache so that they may be collected naturally.
 */

/*ARGSUSED*/
static int
segkp_mem_config_pre_del(void *arg, pgcnt_t delta_pages)
{
        atomic_inc_32(&segkp_indel);
        segkp_cache_free();
        return (0);
}

/*ARGSUSED*/
static void
segkp_mem_config_post_del(void *arg, pgcnt_t delta_pages, int cancelled)
{
        atomic_dec_32(&segkp_indel);
}

static kphysm_setup_vector_t segkp_mem_config_vec = {
        KPHYSM_SETUP_VECTOR_VERSION,
        segkp_mem_config_post_add,
        segkp_mem_config_pre_del,
        segkp_mem_config_post_del,
};

static void
segkpinit_mem_config(struct seg *seg)
{
        int ret;

        ret = kphysm_setup_func_register(&segkp_mem_config_vec, (void *)seg);
        ASSERT(ret == 0);
}