/* vmxc.c: VIRTUAL MEMORY MAPPING FOR MacOS X
*
* $Id: //info.ravenbrook.com/project/mps/version/1.104/code/vmxc.c#1 $
* Copyright (c) 2001 Ravenbrook Limited. See end of file for license.
*
* .design: <design/vm/>
*
* .details: mmap(2) is used to reserve address space by creating a
* mapping to the swap with page access none. mmap(2) is used to map
* pages onto store by creating a copy-on-write mapping to swap.
*
* .assume.not-last: The implementation of VMCreate assumes that mmap()
* will not choose a region which contains the last page in the address
* space, so that the limit of the mapped area is representable.
*
* .assume.mmap.err: ENOMEM is the only error we really expect to get
* from mmap. The others are either caused by invalid params or
* features we don't use. See mmap(2) for details.
*
* .overcommit: Apparently, MacOS X will overcommit, instead of
* returning ENOMEM from mmap. There appears to be no way to tell
* whether the process is running out of swap and no way to reserve the
* swap, apart from actually touching every page.
*/
#include "mpm.h"
#ifndef MPS_OS_XC
#error "vmxc.c is MacOS X specific, but MPS_OS_XC is not set"
#endif
#ifdef VM_RM
#error "vmxc.c compiled with VM_RM set"
#endif /* VM_RM */
#include <sys/types.h>
#include <sys/mman.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h> /* for INT_MAX */
SRCID(vmxc, "$Id: //info.ravenbrook.com/project/mps/version/1.104/code/vmxc.c#1 $");
/* VMStruct -- virtual memory structure */
#define VMSig ((Sig)0x519B3999) /* SIGnature VM */
typedef struct VMStruct {
Sig sig; /* <design/sig/> */
Align align; /* page size */
Addr base, limit; /* boundaries of reserved space */
Size reserved; /* total reserved address space */
Size mapped; /* total mapped memory */
} VMStruct;
/* VMAlign -- return the page size */
Align VMAlign(VM vm)
{
AVERT(VM, vm);
return vm->align;
}
/* VMCheck -- check a VM structure */
Bool VMCheck(VM vm)
{
CHECKS(VM, vm);
CHECKL(vm->base != 0);
CHECKL(vm->limit != 0);
CHECKL(vm->base < vm->limit);
CHECKL(vm->mapped <= vm->reserved);
CHECKL(SizeIsP2(vm->align));
CHECKL(AddrIsAligned(vm->base, vm->align));
CHECKL(AddrIsAligned(vm->limit, vm->align));
return TRUE;
}
/* VMCreate -- reserve some virtual address space, and create a VM structure */
Res VMCreate(VM *vmReturn, Size size)
{
caddr_t addr;
Align align;
VM vm;
AVER(vmReturn != NULL);
align = (Align)getpagesize();
AVER(SizeIsP2(align));
size = SizeAlignUp(size, align);
if(size == 0)
return ResRESOURCE;
/* Map in a page to store the descriptor on. */
AVER(sizeof(caddr_t) == sizeof(Addr)); /* verify address spaces match */
addr = mmap((caddr_t)0, SizeAlignUp(sizeof(VMStruct), align),
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, (off_t)0);
if(addr == (caddr_t)-1) {
int e = errno;
AVER(e == ENOMEM); /* .assume.mmap.err */
if(e == ENOMEM)
return ResMEMORY;
else
return ResFAIL;
}
vm = (VM)addr;
vm->align = align;
addr = mmap((caddr_t)0, size, PROT_NONE, MAP_SHARED | MAP_ANON, -1, (off_t)0);
if(addr == (caddr_t)-1) {
int e = errno;
AVER(e == ENOMEM); /* .assume.mmap.err */
if(e == ENOMEM)
return ResRESOURCE;
else
return ResFAIL;
}
vm->base = (Addr)addr;
vm->limit = AddrAdd(vm->base, size); /* .assume.not-last. */
vm->reserved = size;
vm->mapped = (Size)0;
vm->sig = VMSig;
AVERT(VM, vm);
EVENT_PAA(VMCreate, vm, vm->base, vm->limit);
*vmReturn = vm;
return ResOK;
}
/* VMDestroy -- destroy the VM structure and release the address space */
void VMDestroy(VM vm)
{
int r;
AVERT(VM, vm);
AVER(vm->mapped == (Size)0);
/* This appears to be pretty pointless, since the space descriptor */
/* page is about to vanish completely. However, munmap might fail */
/* for some reason, and this would ensure that it was still */
/* discovered if sigs were being checked. */
vm->sig = SigInvalid;
r = munmap((caddr_t)vm->base, (int)AddrOffset(vm->base, vm->limit));
AVER(r == 0);
r = munmap((caddr_t)vm,
(int)SizeAlignUp(sizeof(VMStruct), vm->align));
AVER(r == 0);
}
/* VMBase, VMLimit -- return the base & limit of the memory reserved */
Addr VMBase(VM vm)
{
AVERT(VM, vm);
return vm->base;
}
Addr VMLimit(VM vm)
{
AVERT(VM, vm);
return vm->limit;
}
/* VMReserved -- return the amount of the memory reserved */
Size VMReserved(VM vm)
{
AVERT(VM, vm);
return vm->reserved;
}
/* VMMapped -- return the amount of the memory committed */
Size VMMapped(VM vm)
{
AVERT(VM, vm);
return vm->mapped;
}
/* VMMap -- commit memory between base & limit */
Res VMMap(VM vm, Addr base, Addr limit)
{
Size size;
AVERT(VM, vm);
AVER(base < limit);
AVER(base >= vm->base);
AVER(limit <= vm->limit);
AVER(AddrOffset(base, limit) <= INT_MAX);
AVER(AddrIsAligned(base, vm->align));
AVER(AddrIsAligned(limit, vm->align));
size = AddrOffset(base, limit);
if(mmap((caddr_t)base, (int)size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_FIXED | MAP_ANON,
-1, (off_t)0)
== (caddr_t)-1) {
AVER(errno == ENOMEM); /* .assume.mmap.err */
return ResMEMORY;
}
vm->mapped += size;
EVENT_PAA(VMMap, vm, base, limit);
return ResOK;
}
/* VMUnmap -- decommit memory between base & limit */
void VMUnmap(VM vm, Addr base, Addr limit)
{
Size size;
caddr_t addr;
AVERT(VM, vm);
AVER(sizeof(int) == sizeof(Addr));
AVER(base < limit);
AVER(base >= vm->base);
AVER(limit <= vm->limit);
AVER(AddrIsAligned(base, vm->align));
AVER(AddrIsAligned(limit, vm->align));
/* .unmap: Map with MAP_ANON, allowing no access. This */
/* effectively depopulates the area from memory, but keeps */
/* it "busy" as far as the OS is concerned, so that it will not */
/* be re-used by other calls to mmap which do not specify */
/* MAP_FIXED. The offset is specified to mmap so that */
/* the OS can merge this mapping with .map.reserve. */
size = AddrOffset(base, limit);
addr = mmap((caddr_t)base, (int)size,
PROT_NONE, MAP_SHARED | MAP_FIXED | MAP_ANON,
-1, (off_t)AddrOffset(vm->base, base));
AVER(addr == (caddr_t)base);
vm->mapped -= size;
EVENT_PAA(VMUnmap, vm, base, limit);
}
/* C. COPYRIGHT AND LICENSE
*
* Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
* All rights reserved. This is an open source license. Contact
* Ravenbrook for commercial licensing options.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Redistributions in any form must be accompanied by information on how
* to obtain complete source code for this software and any accompanying
* software that uses this software. The source code must either be
* included in the distribution or be available for no more than the cost
* of distribution plus a nominal fee, and must be freely redistributable
* under reasonable conditions. For an executable file, complete source
* code means the source code for all modules it contains. It does not
* include source code for modules or files that typically accompany the
* major components of the operating system on which the executable file
* runs.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
* PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/