xnu-517.7.7.tar.gz

[apple/xnu.git] / osfmk / ppc / mappings.c

/*
 * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 *      This file is used to maintain the virtual to real mappings for a PowerPC machine.
 *      The code herein is primarily used to bridge between the pmap layer and the hardware layer.
 *      Currently, some of the function of this module is contained within pmap.c.  We may want to move
 *      all of this into it (or most anyway) for the sake of performance.  We shall see as we write it.
 *
 *      We also depend upon the structure of the phys_entry control block.  We do put some processor 
 *      specific stuff in there.
 *
 */

#include <cpus.h>
#include <debug.h>
#include <mach_kgdb.h>
#include <mach_vm_debug.h>
#include <db_machine_commands.h>

#include <kern/thread.h>
#include <kern/thread_act.h>
#include <mach/vm_attributes.h>
#include <mach/vm_param.h>
#include <vm/vm_fault.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <kern/spl.h>

#include <kern/misc_protos.h>
#include <ppc/exception.h>
#include <ppc/misc_protos.h>
#include <ppc/proc_reg.h>

#include <vm/pmap.h>
#include <ppc/pmap.h>
#include <ppc/mem.h>

#include <ppc/new_screen.h>
#include <ppc/Firmware.h>
#include <ppc/mappings.h>
#include <ddb/db_output.h>

#include <console/video_console.h>              /* (TEST/DEBUG) */

#define PERFTIMES 0

vm_map_t        mapping_map = VM_MAP_NULL;

unsigned int    incrVSID = 0;                                           /* VSID increment value */
unsigned int    mappingdeb0 = 0;                                                
unsigned int    mappingdeb1 = 0;
int ppc_max_adrsp;                                                                      /* Maximum address spaces */                    
                                
addr64_t                *mapdebug;                                                      /* (BRINGUP) */
extern unsigned int DebugWork;                                          /* (BRINGUP) */
                                                
extern unsigned int     hash_table_size;                                                

void mapping_verify(void);
void mapping_phys_unused(ppnum_t pa);

/*
 *      ppc_prot translates from the mach representation of protections to the PPC version.
 *  We also allow for a direct setting of the protection bits. This extends the mach
 *      concepts to allow the greater control we need for Virtual Machines (VMM).
 *      Calculation of it like this saves a memory reference - and maybe a couple of microseconds.
 *      It eliminates the used of this table.
 *      unsigned char ppc_prot[16] = { 0, 3, 2, 2, 3, 3, 2, 2, 0, 1, 2, 3, 0, 1, 2, 3 };
 */

#define ppc_prot(p) ((0xE4E4AFAC >> (p << 1)) & 3)

/*
 *                      About PPC VSID generation:
 *
 *                      This function is called to generate an address space ID. This space ID must be unique within
 *                      the system.  For the PowerPC, it is used to build the VSID.  We build a VSID in the following
 *                      way:  space ID << 4 | segment.  Since a VSID is 24 bits, and out of that, we reserve the last
 *                      4, so, we can have 2^20 (2M) unique IDs.  Each pmap has a unique space ID, so we should be able
 *                      to have 2M pmaps at a time, which we couldn't, we'd run out of memory way before then.  The 
 *                      problem is that only a certain number of pmaps are kept in a free list and if that is full,
 *                      they are release.  This causes us to lose track of what space IDs are free to be reused.
 *                      We can do 4 things: 1) not worry about it, 2) keep all free pmaps, 3) rebuild all mappings
 *                      when the space ID wraps, or 4) scan the list of pmaps and find a free one.
 *
 *                      Yet another consideration is the hardware use of the VSID.  It is used as part of the hash
 *                      calculation for virtual address lookup.  An improperly chosen value could potentially cause
 *                      too many hashes to hit the same bucket, causing PTEG overflows.  The actual hash function
 *                      is (page index XOR vsid) mod number of ptegs. For a 32MB machine, using the suggested
 *                      hash table size, there are 2^12 (8192) PTEGs.  Remember, though, that the bottom 4 bits
 *                      are reserved for the segment number, which means that we really have 2^(12-4) 512 space IDs
 *                      before we start hashing to the same buckets with the same vaddrs. Also, within a space ID,
 *                      every 8192 pages (32MB) within a segment will hash to the same bucket.  That's 8 collisions
 *                      per segment.  So, a scan of every page for 256MB would fill 32 PTEGs completely, but
 *                      with no overflow.  I don't think that this is a problem.
 *
 *                      There may be a problem with the space ID, though. A new space ID is generate (mainly) 
 *                      whenever there is a fork.  There shouldn't really be any problem because (for a 32MB
 *                      machine) we can have 512 pmaps and still not have hash collisions for the same address.
 *                      The potential problem, though, is if we get long-term pmaps that have space IDs that are
 *                      the same modulo 512.  We can reduce this problem by having the segment number be bits
 *                      0-3 of the space ID rather than 20-23.  Doing this means that, in effect, corresponding
 *                      vaddrs in different segments hash to the same PTEG. While this is somewhat of a problem,
 *                      I don't think that it is as signifigant as the other, so, I'll make the space ID
 *                      with segment first.
 *
 *                      The final, and biggest problem is the wrap, which will happen every 2^20 space IDs.
 *                      While this is a problem that should only happen in periods counted in weeks, it can and
 *                      will happen.  This is assuming a monotonically increasing space ID. If we were to search
 *                      for an inactive space ID, there could not be a wrap until there was 2^20 concurrent space IDs.
 *                      That's pretty unlikely to happen.  There couldn't be enough storage to support a million tasks.
 *
 *                      So, what we do is to keep all active pmaps in a chain (anchored from kernel_pmap and
 *                      locked by free_pmap_lock) that is sorted in VSID sequence order.
 *
 *                      Whenever we need a VSID, we walk the list looking for the next in the sequence from
 *                      the last that was freed.  The we allocate that.
 *
 *                      NOTE: We must be called with interruptions off and free_pmap_lock held.
 *
 */

/*
 *              mapping_init();
 *                      Do anything that needs to be done before the mapping system can be used.
 *                      Hash table must be initialized before we call this.
 *
 *                      Calculate the SID increment.  Currently we use size^(1/2) + size^(1/4) + 1;
 */

void mapping_init(void) {

        unsigned int tmp, maxeff, rwidth;
        
        ppc_max_adrsp = maxAdrSp;                                                                       /* Set maximum address spaces */                        
        
        maxeff = 32;                                                                                            /* Assume 32-bit */
        if(per_proc_info[0].pf.Available & pf64Bit) maxeff = 64;        /* Is this a 64-bit machine? */
        
        rwidth = per_proc_info[0].pf.pfMaxVAddr - maxAdrSpb;            /* Reduce address width by width of address space ID */
        if(rwidth > maxeff) rwidth = maxeff;                                            /* If we still have more virtual than effective, clamp at effective */
        
        vm_max_address = 0xFFFFFFFFFFFFFFFFULL >> (64 - rwidth);                /* Get maximum effective address supported */
        vm_max_physical = 0xFFFFFFFFFFFFFFFFULL >> (64 - per_proc_info[0].pf.pfMaxPAddr);       /* Get maximum physical address supported */
        
        if(per_proc_info[0].pf.Available & pf64Bit) {                           /* Are we 64 bit? */
                tmp = 12;                                                                                               /* Size of hash space */
        }
        else {
                __asm__ volatile("cntlzw %0, %1" : "=r" (tmp) : "r" (hash_table_size)); /* Get number of leading 0s */
                tmp = 32 - tmp;                                                                                 /* Size of hash space */
        }

        incrVSID = 1 << ((tmp + 1) >> 1);                                                       /* Get ceiling of sqrt of table size */
        incrVSID |= 1 << ((tmp + 1) >> 2);                                                      /* Get ceiling of quadroot of table size */
        incrVSID |= 1;                                                                                          /* Set bit and add 1 */

        return;

}


/*
 *              mapping_remove(pmap_t pmap, addr64_t va);
 *                      Given a pmap and virtual address, this routine finds the mapping and unmaps it.
 *                      The mapping block will be added to
 *                      the free list.  If the free list threshold is reached, garbage collection will happen.
 *
 *                      We also pass back the next higher mapped address. This is done so that the higher level
 *                      pmap_remove function can release a range of addresses simply by calling mapping_remove
 *                      in a loop until it finishes the range or is returned a vaddr of 0.
 *
 *                      Note that if the mapping is not found, we return the next VA ORed with 1
 *
 */

addr64_t mapping_remove(pmap_t pmap, addr64_t va) {             /* Remove a single mapping for this VADDR 
                                                                                                                   Returns TRUE if a mapping was found to remove */

        mapping         *mp;
        addr64_t        nextva;
        
        disable_preemption();                                                           /* Don't change threads */

        while(1) {                                                                                      /* Keep trying until we truely fail */
                mp = hw_rem_map(pmap, va, &nextva);                             /* Remove a mapping from this pmap */
                if(((unsigned int)mp & mapRetCode) != mapRtRemove) break;       /* If it is gone, we are done */
        }

        enable_preemption();                                                            /* Thread change ok */

        if(!mp) return (nextva | 1);                                            /* Nothing found to unmap */

        if((unsigned int)mp & mapRetCode) {                                     /* Was there a failure? */
        
                panic("mapping_remove: hw_rem_map failed - pmap = %08X, va = %016llX, code = %08X\n",
                        pmap, va, mp);
        }
        
        mapping_free(mp);                                                                       /* Add mapping to the free list */

        return nextva;                                                                          /* Tell them we did it */
}

/*
 *              mapping_make(pmap, va, pa, flags, size, prot) - map a virtual address to a real one 
 *
 *              This routine takes the given parameters, builds a mapping block, and queues it into the 
 *              correct lists.
 *              
 *              pmap (virtual address)          is the pmap to map into
 *              va   (virtual address)          is the 64-bit virtual address that is being mapped
 *              pa      (physical page number)  is the physical page number (i.e., physcial address >> 12). This is
 *                                                                      a 32-bit quantity.
 *              Flags:
 *                      block                                   if 1, mapping is a block, size parameter is used. Note: we do not keep 
 *                                                                      reference and change information or allow protection changes of blocks.
 *                                                                      any changes must first unmap and then remap the area.
 *                      use attribute                   Use specified attributes for map, not defaults for physical page
 *                      perm                                    Mapping is permanent
 *                      cache inhibited                 Cache inhibited (used if use attribute or block set )
 *                      guarded                                 Guarded access (used if use attribute or block set )
 *              size                                            size of block (not used if not block)
 *              prot                                            VM protection bits
 *              attr                                            Cachability/Guardedness    
 *
 *              Returns 0 if mapping was successful.  Returns vaddr that overlaps/collides.
 *              Returns 1 for any other failure.
 *
 *              Note that we make an assumption that all memory in the range 0f 0x0000000080000000 to 0x00000000FFFFFFFF is reserved
 *              for I/O and default the cache attrubutes appropriately.  The caller is free to set whatever they want however.
 *
 *              If there is any physical page that is not found in the physent table, the mapping is forced to be a
 *              block mapping of length 1.  This keeps us from trying to update a physent during later mapping use,
 *              e.g., fault handling.
 *
 *
 */
 
addr64_t mapping_make(pmap_t pmap, addr64_t va, ppnum_t pa, unsigned int flags, unsigned int size, vm_prot_t prot) {    /* Make an address mapping */

        register mapping *mp;
        addr64_t colladdr;
        unsigned int pindex, mflags, pattr, wimg;
        phys_entry *physent;
        int i, nlists;

        disable_preemption();                                                                           /* Don't change threads */

        pindex = 0;
        
        mflags = 0x01000000;                                                                            /* Start building mpFlags field (busy count = 1) */
        
        if(!(flags & mmFlgBlock)) {                                                                     /* Is this a block map? */

                size = 1;                                                                                               /* Set size to 1 page if not block */
         
                physent = mapping_phys_lookup(pa, &pindex);                             /* Get physical entry */
                if(!physent) {                                                                                  /* Did we find the physical page? */
                        mflags |= mpBlock;                                                                      /* Force this to a block if no physent */
                        size = 1;                                                                                       /* Force size to 1 page */
                        pattr = 0;                                                                                      /* Assume normal, non-I/O memory */
                        if((pa & 0xFFF80000) == 0x00080000) pattr = mmFlgCInhib | mmFlgGuarded; /* If this page is in I/O range, set I/O attributes */
                }
                else pattr = ((physent->ppLink & (ppI | ppG)) >> 4);    /* Get the default attributes from physent */
                
                if(flags & mmFlgUseAttr) pattr = flags & (mmFlgCInhib | mmFlgGuarded);  /* Use requested attributes */
        }
        else {                                                                                                          /* This is a block */
                 
                pattr = flags & (mmFlgCInhib | mmFlgGuarded);                   /* Use requested attributes */
                mflags |= mpBlock;                                                                              /* Show that this is a block */
        }
        
        wimg = 0x2;                                                                                                     /* Set basic PPC wimg to 0b0010 - Coherent */
        if(pattr & mmFlgCInhib) wimg |= 0x4;                                            /* Add cache inhibited if we need to */
        if(pattr & mmFlgGuarded) wimg |= 0x1;                                           /* Add guarded if we need to */
        
        mflags = mflags | (pindex << 16);                                                       /* Stick in the physical entry table index */
        
        if(flags & mmFlgPerm) mflags |= mpPerm;                                         /* Set permanent mapping */
        
        size = size - 1;                                                                                        /* Change size to offset */
        if(size > 0xFFFF) return 1;                                                                     /* Leave if size is too big */
        
        nlists = mapSetLists(pmap);                                                                     /* Set number of lists this will be on */
        
        mp = mapping_alloc(nlists);                                                                     /* Get a spare mapping block with this many lists */

                                                                /* the mapping is zero except that the mpLists field is set */
        mp->mpFlags |= mflags;                                                                          /* Add in the rest of the flags to mpLists */
        mp->mpSpace = pmap->space;                                                                      /* Set the address space/pmap lookup ID */
        mp->mpBSize = size;                                                                                     /* Set the size */
        mp->mpPte = 0;                                                                                          /* Set the PTE invalid */
        mp->mpPAddr = pa;                                                                                       /* Set the physical page number */
        mp->mpVAddr = (va & ~mpHWFlags) | (wimg << 3) | ppc_prot(prot); /* Add the protection and attributes to the field */
        
        while(1) {                                                                                                      /* Keep trying... */
                colladdr = hw_add_map(pmap, mp);                                                /* Go add the mapping to the pmap */
                if(!colladdr) {                                                                                 /* All is ok... */
                        enable_preemption();                                                            /* Ok to switch around here */
                        return 0;                                                                                       /* Return... */
                }
                
                if((colladdr & mapRetCode) == mapRtRemove) {                    /* Is our target being removed? */
                        (void)mapping_remove(pmap, colladdr);                           /* Yes, go help out */
                        continue;                                                                                       /* Try to add it now */
                }
                
                if((colladdr & mapRetCode) == mapRtMapDup) {                    /* Is our target already mapped (collision mapping must be identical)? */
                        mapping_free(mp);                                                                       /* Return mapping to the free list */
                        enable_preemption();                                                            /* Ok to switch around here */
                        return 0;                                                                                       /* Normal return */
                }
                
                if(colladdr != mapRtBadLk) {                                                    /* Did it collide? */
                        mapping_free(mp);                                                                       /* Yeah, toss the pending mapping */
                        enable_preemption();                                                            /* Ok to switch around here */
                        return colladdr;                                                                        /* Pass back the overlapping address */
                }
                        
                panic("mapping_make: hw_add_map failed - code = %08X, pmap = %08X, va = %016llX, mapping = %08X\n",
                        colladdr, pmap, va, mp);                                                        /* Die dead */
        }
        
        return 1;                                                                                                       /* Leave... */
}


/*
 *              mapping *mapping_find(pmap, va, *nextva, full) - Finds a mapping 
 *
 *              Looks up the vaddr and returns the mapping and the next mapped va
 *              If full is true, it will descend through all nested pmaps to find actual mapping
 *
 *              Must be called with interruptions disabled or we can hang trying to remove found mapping.
 *
 *              Returns 0 if not found and the virtual address of the mapping if it is
 *              Note that the mappings busy count is bumped. It is the responsibility of the caller
 *              to drop the count.  If this is not done, any attempt to remove the mapping will hang.
 *
 *              NOTE: The nextva field is not valid when full is TRUE.
 *
 *
 */
 
mapping *mapping_find(pmap_t pmap, addr64_t va, addr64_t *nextva, int full) {   /* Make an address mapping */

        register mapping *mp;
        addr64_t        curva;
        pmap_t  curpmap;
        int     nestdepth;

        curpmap = pmap;                                                                                         /* Remember entry */
        nestdepth = 0;                                                                                          /* Set nest depth */
        curva = (addr64_t)va;                                                                                   /* Set current va */

        while(1) {

                mp = hw_find_map(curpmap, curva, nextva);                               /* Find the mapping for this address */
                if((unsigned int)mp == mapRtBadLk) {                                    /* Did we lock up ok? */
                        panic("mapping_find: pmap lock failure - rc = %08X, pmap = %08X\n", mp, curpmap);       /* Die... */
                }
                
                if(!mp || !(mp->mpFlags & mpNest) || !full) break;              /* Are we a nest or are we only going one deep? */

                if(mp->mpFlags & mpSpecial) {                                                   /* Don't chain through a special mapping */
                        mp = 0;                                                                                         /* Set not found */
                        break;
                }

                if(nestdepth++ > 64) {                                                                  /* Have we nested too far down? */
                        panic("mapping_find: too many nested pmaps - va = %016llX, curva = %016llX, pmap = %08X, curpmap = %08X\n",
                                va, curva, pmap, curpmap);
                }
                
                curva = curva + mp->mpNestReloc;                                                /* Relocate va to new pmap */
                curpmap = (pmap_t) pmapTrans[mp->mpSpace].pmapVAddr;    /* Get the address of the nested pmap */
                mapping_drop_busy(mp);                                                                  /* We have everything we need from the mapping */
                
        }

        return mp;                                                                                                      /* Return the mapping if we found one */
}

/*
 *               kern_return_t mapping_protect(pmap_t pmap, addt_t va, vm_prot_t prot, addr64_t *nextva) - change the protection of a virtual page
 *
 *              This routine takes a pmap and virtual address and changes
 *              the protection.  If there are PTEs associated with the mappings, they will be invalidated before
 *              the protection is changed. 
 *
 *              We return success if we change the protection or if there is no page mapped at va.  We return failure if
 *              the va corresponds to a block mapped area or the mapping is permanant.
 *
 *
 */

int mapping_protect(pmap_t pmap, addr64_t va, vm_prot_t prot, addr64_t *nextva) {       /* Change protection of a virtual page */

        int     ret;
        
        ret = hw_protect(pmap, va, ppc_prot(prot), nextva);     /* Try to change the protect here */

        switch (ret) {                                                          /* Decode return code */
        
                case mapRtOK:                                                   /* Changed */
                case mapRtNotFnd:                                               /* Didn't find it */
                        return mapRtOK;                                         /* Ok, return... */
                        break;

                case mapRtBlock:                                                /* Block map, just ignore request */
                case mapRtNest:                                                 /* Nested pmap, just ignore request */
                        return ret;                                                     /* Pass back return code */
                        break;
                        
                default:
                        panic("mapping_protect: hw_protect failed - rc = %d, pmap = %08X, va = %016llX\n", ret, pmap, va);
                
        }

}

/*
 *              void mapping_protect_phys(ppnum_t pa, vm_prot_t prot) - change the protection of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and changes
 *              the protection.  If there are PTEs associated with the mappings, they will be invalidated before
 *              the protection is changed.  There is no limitation on changes, e.g., 
 *              higher to lower, lower to higher.
 *
 *              Any mapping that is marked permanent is not changed
 *
 *              Phys_entry is unlocked.
 */

void mapping_protect_phys(ppnum_t pa, vm_prot_t prot) { /* Change protection of all mappings to page */
        
        unsigned int pindex;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_protect_phys: invalid physical page %08X\n", pa);
        }

        hw_walk_phys(physent, hwpSPrtPhy, hwpSPrtMap, hwpNoop, ppc_prot(prot)); /* Set the new protection for page and mappings */

        return;                                                                                                         /* Leave... */
}


/*
 *              void mapping_clr_mod(ppnum_t pa) - clears the change bit of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and turns
 *              off the change bit. 
 */

void mapping_clr_mod(ppnum_t pa) {                                                              /* Clears the change bit of a physical page */

        unsigned int pindex;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_clr_mod: invalid physical page %08X\n", pa);
        }

        hw_walk_phys(physent, hwpNoop, hwpCCngMap, hwpCCngPhy, 0);      /* Clear change for page and mappings */
        return;                                                                                                         /* Leave... */
}


/*
 *              void mapping_set_mod(ppnum_t pa) - set the change bit of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and turns
 *              on the change bit.  
 */

void mapping_set_mod(ppnum_t pa) {                                                              /* Sets the change bit of a physical page */

        unsigned int pindex;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_set_mod: invalid physical page %08X\n", pa);
        }

        hw_walk_phys(physent, hwpNoop, hwpSCngMap, hwpSCngPhy, 0);      /* Set change for page and mappings */
        return;                                                                                                         /* Leave... */
}


/*
 *              void mapping_clr_ref(ppnum_t pa) - clears the reference bit of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and turns
 *              off the reference bit.  
 */

void mapping_clr_ref(ppnum_t pa) {                                                              /* Clears the reference bit of a physical page */

        unsigned int pindex;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_clr_ref: invalid physical page %08X\n", pa);
        }

        hw_walk_phys(physent, hwpNoop, hwpCRefMap, hwpCRefPhy, 0);      /* Clear reference for page and mappings */
        return;                                                                                                         /* Leave... */
}


/*
 *              void mapping_set_ref(ppnum_t pa) - set the reference bit of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and turns
 *              on the reference bit. 
 */

void mapping_set_ref(ppnum_t pa) {                                                              /* Sets the reference bit of a physical page */

        unsigned int pindex;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_set_ref: invalid physical page %08X\n", pa);
        }

        hw_walk_phys(physent, hwpNoop, hwpSRefMap, hwpSRefPhy, 0);      /* Set reference for page and mappings */
        return;                                                                                                         /* Leave... */
}


/*
 *              void mapping_tst_mod(ppnum_t pa) - test the change bit of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and tests
 *              the changed bit. 
 */

boolean_t mapping_tst_mod(ppnum_t pa) {                                                 /* Tests the change bit of a physical page */

        unsigned int pindex, rc;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_tst_mod: invalid physical page %08X\n", pa);
        }

        rc = hw_walk_phys(physent, hwpTCngPhy, hwpTCngMap, hwpNoop, 0); /* Set change for page and mappings */
        return ((rc & (unsigned long)ppC) != 0);                                        /* Leave with change bit */
}


/*
 *              void mapping_tst_ref(ppnum_t pa) - tests the reference bit of a physical page
 *
 *              This routine takes a physical entry and runs through all mappings attached to it and tests
 *              the reference bit. 
 */

boolean_t mapping_tst_ref(ppnum_t pa) {                                                 /* Tests the reference bit of a physical page */

        unsigned int pindex, rc;
        phys_entry *physent;
        
        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_tst_ref: invalid physical page %08X\n", pa);
        }

        rc = hw_walk_phys(physent, hwpTRefPhy, hwpTRefMap, hwpNoop, 0); /* Test reference for page and mappings */
        return ((rc & (unsigned long)ppR) != 0);                                        /* Leave with reference bit */
}


/*
 *              phys_ent  *mapping_phys_lookup(ppnum_t pp, unsigned int *pindex) - tests the reference bit of a physical page
 *
 *              This routine takes a physical page number and returns the phys_entry associated with it.  It also
 *              calculates the bank address associated with the entry
 *              the reference bit. 
 */

phys_entry *mapping_phys_lookup(ppnum_t pp, unsigned int *pindex) {     /* Finds the physical entry for the page */

        phys_entry *physent;
        int i;
        
        for(i = 0; i < pmap_mem_regions_count; i++) {                           /* Walk through the list */
                if(!(unsigned int)pmap_mem_regions[i].mrPhysTab) continue;      /* Skip any empty lists */
                if((pp < pmap_mem_regions[i].mrStart) || (pp > pmap_mem_regions[i].mrEnd)) continue;    /* This isn't ours */
                
                *pindex = (i * sizeof(mem_region_t)) / 4;                               /* Make the word index to this list */
                
                return &pmap_mem_regions[i].mrPhysTab[pp - pmap_mem_regions[i].mrStart];        /* Return the physent pointer */
        }
        
        return (phys_entry *)0;                                                                         /* Shucks, can't find it... */
        
}




/*
 *              mapping_adjust(void) - Releases free mapping blocks and/or allocates new ones 
 *
 *              This routine frees any mapping blocks queued to mapCtl.mapcrel. It also checks
 *              the number of free mappings remaining, and if below a threshold, replenishes them.
 *              The list will be replenshed from mapCtl.mapcrel if there are enough.  Otherwise,
 *              a new one is allocated.
 *
 *              This routine allocates and/or frees memory and must be called from a safe place. 
 *              Currently, vm_pageout_scan is the safest place. 
 */

thread_call_t                           mapping_adjust_call;
static thread_call_data_t       mapping_adjust_call_data;

void mapping_adjust(void) {                                                                             /* Adjust free mappings */

        kern_return_t   retr = KERN_SUCCESS;
        mappingblok     *mb, *mbn;
        spl_t                   s;
        int                             allocsize, i;
        extern int vm_page_free_count;

        if(mapCtl.mapcmin <= MAPPERBLOK) {
                mapCtl.mapcmin = (sane_size / PAGE_SIZE) / 16;

#if DEBUG
                kprintf("mapping_adjust: minimum entries rqrd = %08X\n", mapCtl.mapcmin);
                kprintf("mapping_adjust: free = %08X; in use = %08X; release = %08X\n",
                  mapCtl.mapcfree, mapCtl.mapcinuse, mapCtl.mapcreln);
#endif
        }

        s = splhigh();                                                                                          /* Don't bother from now on */
        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                panic("mapping_adjust - timeout getting control lock (1)\n");   /* Tell all and die */
        }
        
        if (mapping_adjust_call == NULL) {
                thread_call_setup(&mapping_adjust_call_data, 
                                  (thread_call_func_t)mapping_adjust, 
                                  (thread_call_param_t)NULL);
                mapping_adjust_call = &mapping_adjust_call_data;
        }

        while(1) {                                                                                                      /* Keep going until we've got enough */
                
                allocsize = mapCtl.mapcmin - mapCtl.mapcfree;                   /* Figure out how much we need */
                if(allocsize < 1) break;                                                                /* Leave if we have all we need */
                
                if((unsigned int)(mbn = mapCtl.mapcrel)) {                              /* Can we rescue a free one? */
                        mapCtl.mapcrel = mbn->nextblok;                                         /* Dequeue it */
                        mapCtl.mapcreln--;                                                                      /* Back off the count */
                        allocsize = MAPPERBLOK;                                                         /* Show we allocated one block */                       
                }
        else {                                                                                                  /* No free ones, try to get it */
                        
                        allocsize = (allocsize + MAPPERBLOK - 1) / MAPPERBLOK;  /* Get the number of pages we need */
                        
                        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);            /* Unlock our stuff */
                        splx(s);                                                                                        /* Restore 'rupts */

                        for(; allocsize > 0; allocsize >>= 1) {                         /* Try allocating in descending halves */ 
                                retr = kmem_alloc_wired(mapping_map, (vm_offset_t *)&mbn, PAGE_SIZE * allocsize);       /* Find a virtual address to use */
                                if((retr != KERN_SUCCESS) && (allocsize == 1)) {        /* Did we find any memory at all? */
                                        break;
                                }
                                if(retr == KERN_SUCCESS) break;                                 /* We got some memory, bail out... */
                        }
                
                        allocsize = allocsize * MAPPERBLOK;                                     /* Convert pages to number of maps allocated */
                        s = splhigh();                                                                          /* Don't bother from now on */
                        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                                panic("mapping_adjust - timeout getting control lock (2)\n");   /* Tell all and die */
                        }
                }

                if (retr != KERN_SUCCESS)
                        break;                                                                                          /* Fail to alocate, bail out... */
                for(; allocsize > 0; allocsize -= MAPPERBLOK) {                 /* Release one block at a time */
                        mapping_free_init((vm_offset_t)mbn, 0, 1);                      /* Initialize a non-permanent block */
                        mbn = (mappingblok *)((unsigned int)mbn + PAGE_SIZE);   /* Point to the next slot */
                }

                if ((mapCtl.mapcinuse + mapCtl.mapcfree + (mapCtl.mapcreln * (MAPPERBLOK + 1))) > mapCtl.mapcmaxalloc)
                        mapCtl.mapcmaxalloc = mapCtl.mapcinuse + mapCtl.mapcfree + (mapCtl.mapcreln * (MAPPERBLOK + 1));
        }

        if(mapCtl.mapcholdoff) {                                                                        /* Should we hold off this release? */
                mapCtl.mapcrecurse = 0;                                                                 /* We are done now */
                hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                    /* Unlock our stuff */
                splx(s);                                                                                                /* Restore 'rupts */
                return;                                                                                                 /* Return... */
        }

        mbn = mapCtl.mapcrel;                                                                           /* Get first pending release block */
        mapCtl.mapcrel = 0;                                                                                     /* Dequeue them */
        mapCtl.mapcreln = 0;                                                                            /* Set count to 0 */

        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                            /* Unlock our stuff */
        splx(s);                                                                                                        /* Restore 'rupts */

        while((unsigned int)mbn) {                                                                      /* Toss 'em all */
                mb = mbn->nextblok;                                                                             /* Get the next */
                
                kmem_free(mapping_map, (vm_offset_t) mbn, PAGE_SIZE);   /* Release this mapping block */
        
                mbn = mb;                                                                                               /* Chain to the next */
        }

        __asm__ volatile("eieio");                                                                      /* Make sure all is well */
        mapCtl.mapcrecurse = 0;                                                                         /* We are done now */
        return;
}

/*
 *              mapping_free(mapping *mp) - release a mapping to the free list 
 *
 *              This routine takes a mapping and adds it to the free list.
 *              If this mapping make the block non-empty, we queue it to the free block list.
 *              NOTE: we might want to queue it to the end to keep quelch the pathalogical
 *              case when we get a mapping and free it repeatedly causing the block to chain and unchain.
 *              If this release fills a block and we are above the threshold, we release the block
 */

void mapping_free(struct mapping *mp) {                                                 /* Release a mapping */

        mappingblok     *mb, *mbn;
        spl_t                   s;
        unsigned int    full, mindx, lists;

        mindx = ((unsigned int)mp & (PAGE_SIZE - 1)) >> 6;                      /* Get index to mapping */
        mb = (mappingblok *)((unsigned int)mp & -PAGE_SIZE);            /* Point to the mapping block */
    lists = (mp->mpFlags & mpLists);                                                    /* get #lists */
    if ((lists == 0) || (lists > kSkipListMaxLists))                    /* panic if out of range */
        panic("mapping_free: mpLists invalid\n");

#if 0
        mp->mpFlags = 0x99999999;                                                                       /* (BRINGUP) */ 
        mp->mpSpace = 0x9999;                                                                           /* (BRINGUP) */ 
        mp->mpBSize = 0x9999;                                                                           /* (BRINGUP) */ 
        mp->mpPte   = 0x99999998;                                                                       /* (BRINGUP) */ 
        mp->mpPAddr = 0x99999999;                                                                       /* (BRINGUP) */ 
        mp->mpVAddr = 0x9999999999999999ULL;                                            /* (BRINGUP) */ 
        mp->mpAlias = 0x9999999999999999ULL;                                            /* (BRINGUP) */ 
        mp->mpList0 = 0x9999999999999999ULL;                                            /* (BRINGUP) */ 
        mp->mpList[0] = 0x9999999999999999ULL;                                          /* (BRINGUP) */ 
        mp->mpList[1] = 0x9999999999999999ULL;                                          /* (BRINGUP) */ 
        mp->mpList[2] = 0x9999999999999999ULL;                                          /* (BRINGUP) */ 

        if(lists > mpBasicLists) {                                                                      /* (BRINGUP) */ 
                mp->mpList[3] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[4] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[5] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[6] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[7] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[8] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[9] = 0x9999999999999999ULL;                                  /* (BRINGUP) */ 
                mp->mpList[10] = 0x9999999999999999ULL;                                 /* (BRINGUP) */ 
        }
#endif  
        

        s = splhigh();                                                                                          /* Don't bother from now on */
        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                panic("mapping_free - timeout getting control lock\n"); /* Tell all and die */
        }
        
        full = !(mb->mapblokfree[0] | mb->mapblokfree[1]);                      /* See if full now */ 
        mb->mapblokfree[mindx >> 5] |= (0x80000000 >> (mindx & 31));    /* Flip on the free bit */
    if ( lists > mpBasicLists ) {                                                               /* if big block, lite the 2nd bit too */
        mindx++;
        mb->mapblokfree[mindx >> 5] |= (0x80000000 >> (mindx & 31));
        mapCtl.mapcfree++;
        mapCtl.mapcinuse--;
    }
        
        if(full) {                                                                                                      /* If it was full before this: */
                mb->nextblok = mapCtl.mapcnext;                                                 /* Move head of list to us */
                mapCtl.mapcnext = mb;                                                                   /* Chain us to the head of the list */
                if(!((unsigned int)mapCtl.mapclast))
                        mapCtl.mapclast = mb;
        }

        mapCtl.mapcfree++;                                                                                      /* Bump free count */
        mapCtl.mapcinuse--;                                                                                     /* Decriment in use count */
        
        mapCtl.mapcfreec++;                                                                                     /* Count total calls */

        if(mapCtl.mapcfree > mapCtl.mapcmin) {                                          /* Should we consider releasing this? */
                if(((mb->mapblokfree[0] | 0x80000000) & mb->mapblokfree[1]) == 0xFFFFFFFF) {    /* See if empty now */ 

                        if(mapCtl.mapcnext == mb) {                                                     /* Are we first on the list? */
                                mapCtl.mapcnext = mb->nextblok;                                 /* Unchain us */
                                if(!((unsigned int)mapCtl.mapcnext)) mapCtl.mapclast = 0;       /* If last, remove last */
                        }
                        else {                                                                                          /* We're not first */
                                for(mbn = mapCtl.mapcnext; mbn != 0; mbn = mbn->nextblok) {     /* Search for our block */
                                        if(mbn->nextblok == mb) break;                          /* Is the next one our's? */
                                }
                                if(!mbn) panic("mapping_free: attempt to release mapping block (%08X) not on list\n", mp);
                                mbn->nextblok = mb->nextblok;                                   /* Dequeue us */
                                if(mapCtl.mapclast == mb) mapCtl.mapclast = mbn;        /* If last, make our predecessor last */
                        }
                        
                        if(mb->mapblokflags & mbPerm) {                                         /* Is this permanently assigned? */
                                mb->nextblok = mapCtl.mapcnext;                                 /* Move chain head to us */
                                mapCtl.mapcnext = mb;                                                   /* Chain us to the head */
                                if(!((unsigned int)mb->nextblok)) mapCtl.mapclast = mb; /* If last, make us so */
                        }
                        else {
                                mapCtl.mapcfree -= MAPPERBLOK;                                  /* Remove the block from the free count */
                                mapCtl.mapcreln++;                                                              /* Count on release list */
                                mb->nextblok = mapCtl.mapcrel;                                  /* Move pointer */
                                mapCtl.mapcrel = mb;                                                    /* Chain us in front */
                        }
                }
        }

        if(mapCtl.mapcreln > MAPFRTHRSH) {                                                      /* Do we have way too many releasable mappings? */
                if(hw_compare_and_store(0, 1, &mapCtl.mapcrecurse)) {   /* Make sure we aren't recursing */
                        thread_call_enter(mapping_adjust_call);                         /* Go toss some */
                }
        }
        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                            /* Unlock our stuff */
        splx(s);                                                                                                        /* Restore 'rupts */

        return;                                                                                                         /* Bye, dude... */
}


/*
 *              mapping_alloc(lists) - obtain a mapping from the free list 
 *
 *              This routine takes a mapping off of the free list and returns its address.
 *              The mapping is zeroed, and its mpLists count is set.  The caller passes in
 *              the number of skiplists it would prefer; if this number is greater than 
 *              mpBasicLists (ie, 4) then we need to allocate a 128-byte mapping, which is
 *              just two consequtive free entries coallesced into one.  If we cannot find
 *              two consequtive free entries, we clamp the list count down to mpBasicLists
 *              and return a basic 64-byte node.  Our caller never knows the difference.
 *
 *              If this allocation empties a block, we remove it from the free list.
 *              If this allocation drops the total number of free entries below a threshold,
 *              we allocate a new block.
 *
 */

mapping *mapping_alloc(int lists) {                                                             /* Obtain a mapping */

        register mapping *mp;
        mappingblok     *mb, *mbn;
        spl_t                   s;
        int                             mindx;
        kern_return_t   retr;
    int                         big = (lists > mpBasicLists);                           /* set flag if big block req'd */
        pmap_t                  refpmap, ckpmap;
        unsigned int    space, i;
        int                             ref_count;
        addr64_t                va, nextva;
        extern  pmap_t  free_pmap_list;
        extern  int             free_pmap_count;
        decl_simple_lock_data(extern,free_pmap_lock)
        boolean_t               found_mapping;
        boolean_t               do_rescan;
    
        s = splhigh();                                                                                          /* Don't bother from now on */
        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                panic("mapping_alloc - timeout getting control lock\n");        /* Tell all and die */
        }

        if(!((unsigned int)mapCtl.mapcnext)) {                                          /* Are there any free mappings? */
        
/*
 *              No free mappings.  First, there may be some mapping blocks on the "to be released"
 *              list.  If so, rescue one.  Otherwise, try to steal a couple blocks worth.
 */

                if(mbn = mapCtl.mapcrel) {                                                              /* Try to rescue a block from impending doom */
                        mapCtl.mapcrel = mbn->nextblok;                                         /* Pop the queue */
                        mapCtl.mapcreln--;                                                                      /* Back off the count */
                        mapping_free_init((vm_offset_t)mbn, 0, 1);                      /* Initialize a non-permanent block */
                        goto rescued;
                }

                hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);

                simple_lock(&free_pmap_lock);

                if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                        panic("mapping_alloc - timeout getting control lock\n");        /* Tell all and die */
                }

                if (!((unsigned int)mapCtl.mapcnext)) {

                        refpmap = (pmap_t)cursor_pmap->pmap_link.next;
                        space = mapCtl.mapcflush.spacenum;
                        while (refpmap != cursor_pmap) {
                                if(((pmap_t)(refpmap->pmap_link.next))->spaceNum > space) break;
                                refpmap = (pmap_t)refpmap->pmap_link.next;
                        }

                        ckpmap = refpmap;
                        va = mapCtl.mapcflush.addr;
                        found_mapping = FALSE;

                        while (mapCtl.mapcfree <= (MAPPERBLOK*2)) {

                                hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);

                                ckpmap = (pmap_t)ckpmap->pmap_link.next;

                                if ((ckpmap->stats.resident_count != 0) && (ckpmap != kernel_pmap)) {
                                        do_rescan = TRUE;
                                        for (i=0;i<8;i++) {
                                                mp = hw_purge_map(ckpmap, va, &nextva);

                                                if((unsigned int)mp & mapRetCode) {
                                                        panic("mapping_alloc: hw_purge_map failed - pmap = %08X, va = %16llX, code = %08X\n", ckpmap, va, mp);
                                                }

                                                if(!mp) { 
                                                        if (do_rescan)
                                                                do_rescan = FALSE;
                                                        else
                                                                break;
                                                } else {
                                                        mapping_free(mp);
                                                        found_mapping = TRUE;
                                                }

                                                va = nextva;
                                        }
                                }

                                if (ckpmap == refpmap) {
                                        if (found_mapping == FALSE)
                                                panic("no valid pmap to purge mappings\n");
                                        else
                                                found_mapping = FALSE;
                                }

                                if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                                        panic("mapping_alloc - timeout getting control lock\n");        /* Tell all and die */
                                }

                        }

                        mapCtl.mapcflush.spacenum = ckpmap->spaceNum;
                        mapCtl.mapcflush.addr = nextva;
                }

                simple_unlock(&free_pmap_lock);
        }

rescued:

        mb = mapCtl.mapcnext;
    
    if ( big ) {                                                                                                /* if we need a big (128-byte) mapping */
        mapCtl.mapcbig++;                                                                               /* count attempts to allocate a big mapping */
        mbn = NULL;                                                                                             /* this will be prev ptr */
        mindx = 0;
        while( mb ) {                                                                                   /* loop over mapping blocks with free entries */
            mindx = mapalc2(mb);                                                                /* try for 2 consequtive free bits in this block */

           if ( mindx ) break;                                                                  /* exit loop if we found them */
            mbn = mb;                                                                                   /* remember previous block */
            mb = mb->nextblok;                                                                  /* move on to next block */
        }
        if ( mindx == 0 ) {                                                                             /* if we couldn't find 2 consequtive bits... */
            mapCtl.mapcbigfails++;                                                              /* count failures */
            big = 0;                                                                                    /* forget that we needed a big mapping */
            lists = mpBasicLists;                                                               /* clamp list count down to the max in a 64-byte mapping */
            mb = mapCtl.mapcnext;                                                               /* back to the first block with a free entry */
        }
        else {                                                                                                  /* if we did find a big mapping */
            mapCtl.mapcfree--;                                                                  /* Decrement free count twice */
            mapCtl.mapcinuse++;                                                                 /* Bump in use count twice */
            if ( mindx < 0 ) {                                                                  /* if we just used the last 2 free bits in this block */
                if (mbn) {                                                                              /* if this wasn't the first block */
                    mindx = -mindx;                                                             /* make positive */
                    mbn->nextblok = mb->nextblok;                               /* unlink this one from the middle of block list */
                    if (mb ==  mapCtl.mapclast) {                               /* if we emptied last block */
                        mapCtl.mapclast = mbn;                                  /* then prev block is now last */
                    }
                }
            }
        }
    }
    
    if ( !big ) {                                                                                               /* if we need a small (64-byte) mapping */
        if(!(mindx = mapalc1(mb)))                                                              /* Allocate a 1-bit slot */
            panic("mapping_alloc - empty mapping block detected at %08X\n", mb);
    }
        
        if(mindx < 0) {                                                                                         /* Did we just take the last one */
                mindx = -mindx;                                                                                 /* Make positive */
                mapCtl.mapcnext = mb->nextblok;                                                 /* Remove us from the list */
                if(!((unsigned int)mapCtl.mapcnext)) mapCtl.mapclast = 0;       /* Removed the last one */
        }
        
        mapCtl.mapcfree--;                                                                                      /* Decrement free count */
        mapCtl.mapcinuse++;                                                                                     /* Bump in use count */
        
        mapCtl.mapcallocc++;                                                                            /* Count total calls */

/*
 *      Note: in the following code, we will attempt to rescue blocks only one at a time.
 *      Eventually, after a few more mapping_alloc calls, we will catch up.  If there are none
 *      rescueable, we will kick the misc scan who will allocate some for us.  We only do this
 *      if we haven't already done it.
 *      For early boot, we are set up to only rescue one block at a time.  This is because we prime
 *      the release list with as much as we need until threads start.
 */

        if(mapCtl.mapcfree < mapCtl.mapcmin) {                                          /* See if we need to replenish */
                if(mbn = mapCtl.mapcrel) {                                                              /* Try to rescue a block from impending doom */
                        mapCtl.mapcrel = mbn->nextblok;                                         /* Pop the queue */
                        mapCtl.mapcreln--;                                                                      /* Back off the count */
                        mapping_free_init((vm_offset_t)mbn, 0, 1);                      /* Initialize a non-permanent block */
                }
                else {                                                                                                  /* We need to replenish */
                        if (mapCtl.mapcfree < (mapCtl.mapcmin / 4)) {
                                if(hw_compare_and_store(0, 1, &mapCtl.mapcrecurse)) {   /* Make sure we aren't recursing */
                                        thread_call_enter(mapping_adjust_call);                 /* Go allocate some more */
                                }
                        }
                }
        }

        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                            /* Unlock our stuff */
        splx(s);                                                                                                        /* Restore 'rupts */
        
        mp = &((mapping *)mb)[mindx];                                                           /* Point to the allocated mapping */
    mp->mpFlags = lists;                                                                                /* set the list count */


        return mp;                                                                                                      /* Send it back... */
}


void
consider_mapping_adjust()
{
        spl_t                   s;

        s = splhigh();                                                                                          /* Don't bother from now on */
        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {     /* Lock the control header */ 
                panic("consider_mapping_adjust -- lock timeout\n");
        }

        if (mapCtl.mapcfree < (mapCtl.mapcmin / 4)) {
                if(hw_compare_and_store(0, 1, &mapCtl.mapcrecurse)) {   /* Make sure we aren't recursing */
                        thread_call_enter(mapping_adjust_call);                 /* Go allocate some more */
                }
        }

        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                            /* Unlock our stuff */
        splx(s);                                                                                                        /* Restore 'rupts */
        
}



/*
 *              void mapping_free_init(mb, perm) - Adds a block of storage to the free mapping list
 *
 *              The mapping block is a page size area on a page boundary.  It contains 1 header and 63
 *              mappings.  This call adds and initializes a block for use.  Mappings come in two sizes,
 *              64 and 128 bytes (the only difference is the number of skip-lists.)  When we allocate a
 *              128-byte mapping we just look for two consequtive free 64-byte mappings, so most of the
 *              code only deals with "basic" 64-byte mappings.  This works for two reasons:
 *                      - Only one in 256 mappings is big, so they are rare.
 *                      - If we cannot find two consequtive free mappings, we just return a small one.
 *                        There is no problem with doing this, except a minor performance degredation.
 *              Therefore, all counts etc in the mapping control structure are in units of small blocks.
 *      
 *              The header contains a chain link, bit maps, a virtual to real translation mask, and
 *              some statistics. Bit maps map each slot on the page (bit 0 is not used because it 
 *              corresponds to the header).  The translation mask is the XOR of the virtual and real
 *              addresses (needless to say, the block must be wired).
 *
 *              We handle these mappings the same way as saveareas: the block is only on the chain so
 *              long as there are free entries in it.
 *
 *              Empty blocks are garbage collected when there are at least mapCtl.mapcmin pages worth of free 
 *              mappings. Blocks marked PERM won't ever be released.
 *
 *              If perm is negative, the mapping is initialized, but immediately queued to the mapCtl.mapcrel
 *              list.  We do this only at start up time. This is done because we only allocate blocks 
 *              in the pageout scan and it doesn't start up until after we run out of the initial mappings.
 *              Therefore, we need to preallocate a bunch, but we don't want them to be permanent.  If we put
 *              them on the release queue, the allocate routine will rescue them.  Then when the
 *              pageout scan starts, all extra ones will be released.
 *
 */


void mapping_free_init(vm_offset_t mbl, int perm, boolean_t locked) {           
                                                                                                                        /* Set's start and end of a block of mappings
                                                                                                                           perm indicates if the block can be released 
                                                                                                                           or goes straight to the release queue .
                                                                                                                           locked indicates if the lock is held already */
                                                                                                                   
        mappingblok     *mb;
        spl_t           s;
        int                     i;
        addr64_t        raddr;
        ppnum_t         pp;

        mb = (mappingblok *)mbl;                                                                /* Start of area */     
        
        if(perm >= 0) {                                                                                 /* See if we need to initialize the block */
                if(perm) {
                        raddr = (addr64_t)((unsigned int)mbl);                  /* Perm means V=R */
                        mb->mapblokflags = mbPerm;                                              /* Set perm */
//                      mb->mapblokflags |= (unsigned int)mb;                   /* (BRINGUP) */
                }
                else {
                        pp = pmap_find_phys(kernel_pmap, (addr64_t)mbl);        /* Get the physical page */
                        if(!pp) {                                                                               /* What gives?  Where's the page? */
                                panic("mapping_free_init: could not find translation for vaddr %016llX\n", (addr64_t)mbl);
                        }
                        
                        raddr = (addr64_t)pp << 12;                                             /* Convert physical page to physical address */
                        mb->mapblokflags = 0;                                                   /* Set not perm */
//                      mb->mapblokflags |= (unsigned int)mb;                   /* (BRINGUP) */
                }
                
                mb->mapblokvrswap = raddr ^ (addr64_t)((unsigned int)mbl);              /* Form translation mask */
                
                mb->mapblokfree[0] = 0x7FFFFFFF;                                        /* Set first 32 (minus 1) free */
                mb->mapblokfree[1] = 0xFFFFFFFF;                                        /* Set next 32 free */
        }
        
        s = splhigh();                                                                                  /* Don't bother from now on */
        if(!locked) {                                                                                   /* Do we need the lock? */
                if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {             /* Lock the control header */ 
                        panic("mapping_free_init: timeout getting control lock\n");     /* Tell all and die */
                }
        }
        
        if(perm < 0) {                                                                                  /* Direct to release queue? */
                mb->nextblok = mapCtl.mapcrel;                                          /* Move forward pointer */
                mapCtl.mapcrel = mb;                                                            /* Queue us on in */
                mapCtl.mapcreln++;                                                                      /* Count the free block */
        }
        else {                                                                                                  /* Add to the free list */
                
                mb->nextblok = 0;                                                                       /* We always add to the end */
                mapCtl.mapcfree += MAPPERBLOK;                                          /* Bump count */
                
                if(!((unsigned int)mapCtl.mapcnext)) {                          /* First entry on list? */
                        mapCtl.mapcnext = mapCtl.mapclast = mb;                 /* Chain to us */
                }
                else {                                                                                          /* We are not the first */
                        mapCtl.mapclast->nextblok = mb;                                 /* Point the last to us */
                        mapCtl.mapclast = mb;                                                   /* We are now last */
                }
        }
                
        if(!locked) {                                                                                   /* Do we need to unlock? */
                hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);            /* Unlock our stuff */
        }

        splx(s);                                                                                                /* Restore 'rupts */
        return;                                                                                                 /* All done, leave... */
}


/*
 *              void mapping_prealloc(unsigned int) - Preallocates mapppings for large request
 *      
 *              No locks can be held, because we allocate memory here.
 *              This routine needs a corresponding mapping_relpre call to remove the
 *              hold off flag so that the adjust routine will free the extra mapping
 *              blocks on the release list.  I don't like this, but I don't know
 *              how else to do this for now...
 *
 */

void mapping_prealloc(unsigned int size) {                                      /* Preallocates mapppings for large request */

        int     nmapb, i;
        kern_return_t   retr;
        mappingblok     *mbn;
        spl_t           s;

        s = splhigh();                                                                                  /* Don't bother from now on */
        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {             /* Lock the control header */ 
                panic("mapping_prealloc - timeout getting control lock\n");     /* Tell all and die */
        }

        nmapb = (size >> 12) + mapCtl.mapcmin;                                  /* Get number of entries needed for this and the minimum */
        
        mapCtl.mapcholdoff++;                                                                   /* Bump the hold off count */
        
        if((nmapb = (nmapb - mapCtl.mapcfree)) <= 0) {                  /* Do we already have enough? */
                hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);            /* Unlock our stuff */
                splx(s);                                                                                        /* Restore 'rupts */
                return;
        }
        if (!hw_compare_and_store(0, 1, &mapCtl.mapcrecurse)) {     /* Make sure we aren't recursing */
                hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                    /* Unlock our stuff */
                splx(s);                                                                                        /* Restore 'rupts */
                return;
        }
        nmapb = (nmapb + MAPPERBLOK - 1) / MAPPERBLOK;                  /* Get number of blocks to get */
        
        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                    /* Unlock our stuff */
        splx(s);                                                                                                /* Restore 'rupts */
        
        for(i = 0; i < nmapb; i++) {                                                    /* Allocate 'em all */
                retr = kmem_alloc_wired(mapping_map, (vm_offset_t *)&mbn, PAGE_SIZE);   /* Find a virtual address to use */
                if(retr != KERN_SUCCESS)                                                        /* Did we get some memory? */
                        break;
                mapping_free_init((vm_offset_t)mbn, -1, 0);                     /* Initialize on to the release queue */
        }
        if ((mapCtl.mapcinuse + mapCtl.mapcfree + (mapCtl.mapcreln * (MAPPERBLOK + 1))) > mapCtl.mapcmaxalloc)
                mapCtl.mapcmaxalloc = mapCtl.mapcinuse + mapCtl.mapcfree + (mapCtl.mapcreln * (MAPPERBLOK + 1));

        mapCtl.mapcrecurse = 0;                                                                         /* We are done now */
}

/*
 *              void mapping_relpre(void) - Releases preallocation release hold off
 *      
 *              This routine removes the
 *              hold off flag so that the adjust routine will free the extra mapping
 *              blocks on the release list.  I don't like this, but I don't know
 *              how else to do this for now...
 *
 */

void mapping_relpre(void) {                                                                     /* Releases release hold off */

        spl_t           s;

        s = splhigh();                                                                                  /* Don't bother from now on */
        if(!hw_lock_to((hw_lock_t)&mapCtl.mapclock, LockTimeOut)) {             /* Lock the control header */ 
                panic("mapping_relpre - timeout getting control lock\n");       /* Tell all and die */
        }
        if(--mapCtl.mapcholdoff < 0) {                                                  /* Back down the hold off count */
                panic("mapping_relpre: hold-off count went negative\n");
        }

        hw_lock_unlock((hw_lock_t)&mapCtl.mapclock);                    /* Unlock our stuff */
        splx(s);                                                                                                /* Restore 'rupts */
}

/*
 *              void mapping_free_prime(void) - Primes the mapping block release list
 *
 *              See mapping_free_init.
 *              No locks can be held, because we allocate memory here.
 *              One processor running only.
 *
 */

void mapping_free_prime(void) {                                                                 /* Primes the mapping block release list */

        int     nmapb, i;
        kern_return_t   retr;
        mappingblok     *mbn;
        vm_offset_t     mapping_min;
        
        retr = kmem_suballoc(kernel_map, &mapping_min, sane_size / 16,
                             FALSE, TRUE, &mapping_map);

        if (retr != KERN_SUCCESS)
                panic("mapping_free_prime: kmem_suballoc failed");


        nmapb = (mapCtl.mapcfree + mapCtl.mapcinuse + MAPPERBLOK - 1) / MAPPERBLOK;     /* Get permanent allocation */
        nmapb = nmapb * 4;                                                                                      /* Get 4 times our initial allocation */

#if DEBUG
        kprintf("mapping_free_prime: free = %08X; in use = %08X; priming = %08X\n", 
          mapCtl.mapcfree, mapCtl.mapcinuse, nmapb);
#endif
        
        for(i = 0; i < nmapb; i++) {                                                            /* Allocate 'em all */
                retr = kmem_alloc_wired(mapping_map, (vm_offset_t *)&mbn, PAGE_SIZE);   /* Find a virtual address to use */
                if(retr != KERN_SUCCESS) {                                                              /* Did we get some memory? */
                        panic("Whoops...  Not a bit of wired memory left for anyone\n");
                }
                mapping_free_init((vm_offset_t)mbn, -1, 0);                             /* Initialize onto release queue */
        }
        if ((mapCtl.mapcinuse + mapCtl.mapcfree + (mapCtl.mapcreln * (MAPPERBLOK + 1))) > mapCtl.mapcmaxalloc)
                mapCtl.mapcmaxalloc = mapCtl.mapcinuse + mapCtl.mapcfree + (mapCtl.mapcreln * (MAPPERBLOK + 1));
}



mapping_fake_zone_info(int *count, vm_size_t *cur_size, vm_size_t *max_size, vm_size_t *elem_size,
                       vm_size_t *alloc_size, int *collectable, int *exhaustable)
{
        *count      = mapCtl.mapcinuse;
        *cur_size   = ((PAGE_SIZE / (MAPPERBLOK + 1)) * (mapCtl.mapcinuse + mapCtl.mapcfree)) + (PAGE_SIZE * mapCtl.mapcreln);
        *max_size   = (PAGE_SIZE / (MAPPERBLOK + 1)) * mapCtl.mapcmaxalloc;
        *elem_size  = (PAGE_SIZE / (MAPPERBLOK + 1));
        *alloc_size = PAGE_SIZE;

        *collectable = 1;
        *exhaustable = 0;
}


/*
 *              addr64_t        mapping_p2v(pmap_t pmap, ppnum_t pa) - Finds first virtual mapping of a physical page in a space
 *
 *              First looks up  the physical entry associated witht the physical page.  Then searches the alias
 *              list for a matching pmap.  It grabs the virtual address from the mapping, drops busy, and returns 
 *              that.
 *
 */

addr64_t        mapping_p2v(pmap_t pmap, ppnum_t pa) {                          /* Finds first virtual mapping of a physical page in a space */

        spl_t s;
        mapping *mp;
        unsigned int pindex;
        phys_entry *physent;
        addr64_t va;

        physent = mapping_phys_lookup(pa, &pindex);                                     /* Get physical entry */
        if(!physent) {                                                                                          /* Did we find the physical page? */
                panic("mapping_p2v: invalid physical page %08X\n", pa);
        }

        s = splhigh();                                                                                  /* Make sure interruptions are disabled */

        mp = (mapping *) hw_find_space(physent, pmap->space);   /* Go find the first mapping to the page from the requested pmap */

        if(mp) {                                                                                                /* Did we find one? */
                va = mp->mpVAddr & -4096;                                                       /* If so, get the cleaned up vaddr */
                mapping_drop_busy(mp);                                                          /* Go ahead and relase the mapping now */
        }
        else va = 0;                                                                                    /* Return failure */

        splx(s);                                                                                                /* Restore 'rupts */
        
        return va;                                                                                              /* Bye, bye... */
        
}

/*
 *      phystokv(addr)
 *
 *      Convert a physical address to a kernel virtual address if
 *      there is a mapping, otherwise return NULL
 */

vm_offset_t phystokv(vm_offset_t pa) {

        addr64_t        va;
        ppnum_t pp;

        pp = pa >> 12;                                                                                  /* Convert to a page number */
        
        if(!(va = mapping_p2v(kernel_pmap, pp))) {
                return 0;                                                                                       /* Can't find it, return 0... */
        }
        
        return (va | (pa & (PAGE_SIZE - 1)));                                   /* Build and return VADDR... */

}

/*
 *      kvtophys(addr)
 *
 *      Convert a kernel virtual address to a physical address
 */
vm_offset_t kvtophys(vm_offset_t va) {

        return pmap_extract(kernel_pmap, va);                                   /* Find mapping and lock the physical entry for this mapping */

}

/*
 *              void ignore_zero_fault(boolean_t) - Sets up to ignore or honor any fault on 
 *              page 0 access for the current thread.
 *
 *              If parameter is TRUE, faults are ignored
 *              If parameter is FALSE, faults are honored
 *
 */

void ignore_zero_fault(boolean_t type) {                                /* Sets up to ignore or honor any fault on page 0 access for the current thread */

        if(type) current_act()->mact.specFlags |= ignoreZeroFault;      /* Ignore faults on page 0 */
        else     current_act()->mact.specFlags &= ~ignoreZeroFault;     /* Honor faults on page 0 */
        
        return;                                                                                         /* Return the result or 0... */
}


/* 
 *              Copies data between a physical page and a virtual page, or 2 physical.  This is used to 
 *              move data from the kernel to user state. Note that the "which" parm
 *              says which of the parameters is physical and if we need to flush sink/source.  
 *              Note that both addresses may be physicical but only one may be virtual
 *
 *              The rules are that the size can be anything.  Either address can be on any boundary
 *              and span pages.  The physical data must be congiguous as must the virtual.
 *
 *              We can block when we try to resolve the virtual address at each page boundary.
 *              We don't check protection on the physical page.
 *
 *              Note that we will not check the entire range and if a page translation fails,
 *              we will stop with partial contents copied.
 *
 */
 
kern_return_t copypv(addr64_t source, addr64_t sink, unsigned int size, int which) {
 
        vm_map_t map;
        kern_return_t ret;
        addr64_t pa, nextva, vaddr, paddr;
        register mapping *mp;
        spl_t s;
        unsigned int sz, left, lop, csize;
        int needtran, bothphys;
        unsigned int pindex;
        phys_entry *physent;
        vm_prot_t prot;
        int orig_which;

        orig_which = which;

        map = (which & cppvKmap) ? kernel_map : current_map_fast();

        if((which & (cppvPsrc | cppvPsnk)) == 0 ) {             /* Make sure that only one is virtual */
                panic("copypv: no more than 1 parameter may be virtual\n");     /* Not allowed */
        }
        
        bothphys = 1;                                                                   /* Assume both are physical */
        
        if(!(which & cppvPsnk)) {                                               /* Is there a virtual page here? */
                vaddr = sink;                                                           /* Sink side is virtual */
                bothphys = 0;                                                           /* Show both aren't physical */
                prot = VM_PROT_READ | VM_PROT_WRITE;            /* Sink always must be read/write */
        } else if(!(which & cppvPsrc)) {                                /* Source side is virtual */
                vaddr = source;                                                         /* Source side is virtual */
                bothphys = 0;                                                           /* Show both aren't physical */
                prot = VM_PROT_READ;                                            /* Virtual source is always read only */
        }

        needtran = 1;                                                                   /* Show we need to map the virtual the first time */
        s = splhigh();                                                                  /* Don't bother me */

        while(size) {

                if(!bothphys && (needtran || !(vaddr & 4095LL))) {      /* If first time or we stepped onto a new page, we need to translate */
                        if(!needtran) {                                                 /* If this is not the first translation, we need to drop the old busy */
                                mapping_drop_busy(mp);                          /* Release the old mapping now */
                        }
                        needtran = 0;
                        
                        while(1) {
                                mp = mapping_find(map->pmap, vaddr, &nextva, 1);        /* Find and busy the mapping */
                                if(!mp) {                                                       /* Was it there? */
                                        if(per_proc_info[cpu_number()].istackptr == 0)
                                                panic("copypv: No vaild mapping on memory %s %x", "RD", vaddr);

                                        splx(s);                                                /* Restore the interrupt level */
                                        ret = vm_fault(map, trunc_page_32((vm_offset_t)vaddr), prot, FALSE, FALSE, NULL, 0);    /* Didn't find it, try to fault it in... */
                                
                                        if(ret != KERN_SUCCESS)return KERN_FAILURE;     /* Didn't find any, return no good... */
                                        
                                        s = splhigh();                                  /* Don't bother me */
                                        continue;                                               /* Go try for the map again... */
        
                                }
                                if (mp->mpVAddr & mpI) {                 /* cache inhibited, so force the appropriate page to be flushed before */
                                        if (which & cppvPsrc)            /* and after the copy to avoid cache paradoxes */
                                                which |= cppvFsnk;
                                        else
                                                which |= cppvFsrc;
                                } else
                                        which = orig_which;

                                /* Note that we have to have the destination writable.  So, if we already have it, or we are mapping the source,
                                        we can just leave.
                                */              
                                if((which & cppvPsnk) || !(mp->mpVAddr & 1)) break;             /* We got it mapped R/W or the source is not virtual, leave... */
                        
                                mapping_drop_busy(mp);                          /* Go ahead and release the mapping for now */
                                if(per_proc_info[cpu_number()].istackptr == 0)
                                        panic("copypv: No vaild mapping on memory %s %x", "RDWR", vaddr);
                                splx(s);                                                        /* Restore the interrupt level */
                                
                                ret = vm_fault(map, trunc_page_32((vm_offset_t)vaddr), VM_PROT_READ | VM_PROT_WRITE, FALSE, FALSE, NULL, 0);    /* check for a COW area */
                                if (ret != KERN_SUCCESS) return KERN_FAILURE;   /* We couldn't get it R/W, leave in disgrace... */
                                s = splhigh();                                          /* Don't bother me */
                        }
                        paddr = ((addr64_t)mp->mpPAddr << 12) + (vaddr - (mp->mpVAddr & -4096LL));        /* construct the physical address... this calculation works */
                                                                                                          /* properly on both single page and block mappings */
                        if(which & cppvPsrc) sink = paddr;              /* If source is physical, then the sink is virtual */
                        else source = paddr;                                    /* Otherwise the source is */
                }
                        
                lop = (unsigned int)(4096LL - (sink & 4095LL));         /* Assume sink smallest */
                if(lop > (unsigned int)(4096LL - (source & 4095LL))) lop = (unsigned int)(4096LL - (source & 4095LL));  /* No, source is smaller */
                
                csize = size;                                                           /* Assume we can copy it all */
                if(lop < size) csize = lop;                                     /* Nope, we can't do it all */
                
                if(which & cppvFsrc) flush_dcache64(source, csize, 1);  /* If requested, flush source before move */
                if(which & cppvFsnk) flush_dcache64(sink, csize, 1);    /* If requested, flush sink before move */

                bcopy_physvir(source, sink, csize);                     /* Do a physical copy, virtually */
                
                if(which & cppvFsrc) flush_dcache64(source, csize, 1);  /* If requested, flush source after move */
                if(which & cppvFsnk) flush_dcache64(sink, csize, 1);    /* If requested, flush sink after move */

/*
 *              Note that for certain ram disk flavors, we may be copying outside of known memory.
 *              Therefore, before we try to mark it modifed, we check if it exists.
 */

                if( !(which & cppvNoModSnk)) {
                        physent = mapping_phys_lookup(sink >> 12, &pindex);     /* Get physical entry for sink */
                        if(physent) mapping_set_mod((ppnum_t)(sink >> 12));             /* Make sure we know that it is modified */
                }
                if( !(which & cppvNoRefSrc)) {
                        physent = mapping_phys_lookup(source >> 12, &pindex);   /* Get physical entry for source */
                        if(physent) mapping_set_ref((ppnum_t)(source >> 12));           /* Make sure we know that it is modified */
                }
                size = size - csize;                                            /* Calculate what is left */
                vaddr = vaddr + csize;                                          /* Move to next sink address */
                source = source + csize;                                        /* Bump source to next physical address */
                sink = sink + csize;                                            /* Bump sink to next physical address */
        }
        
        if(!bothphys) mapping_drop_busy(mp);                    /* Go ahead and release the mapping of the virtual page if any */
        splx(s);                                                                                /* Open up for interrupts */

        return KERN_SUCCESS;
}


/*
 *      Debug code 
 */

void mapping_verify(void) {

        spl_t           s;
        mappingblok     *mb, *mbn;
        int                     relncnt;
        unsigned int    dumbodude;

        dumbodude = 0;
        
        s = splhigh();                                                                                  /* Don't bother from now on */

        mbn = 0;                                                                                                /* Start with none */
        for(mb = mapCtl.mapcnext; mb; mb = mb->nextblok) {              /* Walk the free chain */
                if((mappingblok *)(mb->mapblokflags & 0x7FFFFFFF) != mb) {      /* Is tag ok? */
                        panic("mapping_verify: flags tag bad, free chain; mb = %08X, tag = %08X\n", mb, mb->mapblokflags);
                }
                mbn = mb;                                                                                       /* Remember the last one */
        }
        
        if(mapCtl.mapcnext && (mapCtl.mapclast != mbn)) {               /* Do we point to the last one? */
                panic("mapping_verify: last pointer bad; mb = %08X, mapclast = %08X\n", mb, mapCtl.mapclast);
        }
        
        relncnt = 0;                                                                                    /* Clear count */
        for(mb = mapCtl.mapcrel; mb; mb = mb->nextblok) {               /* Walk the release chain */
                dumbodude |= mb->mapblokflags;                                          /* Just touch it to make sure it is mapped */
                relncnt++;                                                                                      /* Count this one */
        }
        
        if(mapCtl.mapcreln != relncnt) {                                                        /* Is the count on release queue ok? */
                panic("mapping_verify: bad release queue count; mapcreln = %d, cnt = %d, ignore this = %08X\n", mapCtl.mapcreln, relncnt, dumbodude);
        }

        splx(s);                                                                                                /* Restore 'rupts */

        return;
}

void mapping_phys_unused(ppnum_t pa) {

        unsigned int pindex;
        phys_entry *physent;

        physent = mapping_phys_lookup(pa, &pindex);                             /* Get physical entry */
        if(!physent) return;                                                                    /* Did we find the physical page? */

        if(!(physent->ppLink & ~(ppLock | ppN | ppFlags))) return;      /* No one else is here */
        
        panic("mapping_phys_unused: physical page (%08X) in use, physent = %08X\n", pa, physent);
        
}