/* vmli.c: VIRTUAL MEMORY MAPPING FOR LINUX
*
* $Id: //info.ravenbrook.com/project/mps/version/1.103/code/vmli.c#1 $
* Copyright (c) 2001 Ravenbrook Limited. See end of file for license.
*
* .purpose: This is the implementation of the virtual memory mapping
* interface (vm.h) for Linux. It was created by copying vmo1.c (the
* DIGITAL UNIX implementation) as that seemed to be closest.
*
* .design: See <design/vm/>. .design.linux: mmap(2) is used to
* reserve address space by creating a mapping with page access none.
* mmap(2) is used to map pages onto store by creating a copy-on-write
* (MAP_PRIVATE) mapping with the flag MAP_ANONYMOUS.
*
* .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.
*
* .assume.off_t: We assume that the Size type (defined by the MM) fits
* in the off_t type (define by the system (POSIX?)). In fact we test
* the more stringent requirement that they are the same size. This
* assumption is made in VMUnmap.
*
* .remap: Possibly this should use mremap to reduce the number of
* distinct mappings. According to our current testing, it doesn't
* seem to be a problem.
*/
/* Use all extensions */
#define _GNU_SOURCE 1
/* for open(2) */
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
/* for mmap(2), munmap(2) */
#include <sys/mman.h>
/* for errno(2) */
#include <errno.h>
/* for sysconf(2), close(2) */
#include <unistd.h>
#include "mpm.h"
#ifndef MPS_OS_LI
#error "vmli.c is LINUX specific, but MPS_OS_LI is not set"
#endif
SRCID(vmli, "$Id: //info.ravenbrook.com/project/mps/version/1.103/code/vmli.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 page size */
Align VMAlign(VM vm)
{
AVERT(VM, vm);
return vm->align;
}
/* VMCheck -- check a VM */
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)
{
Align align;
VM vm;
long pagesize;
void *addr;
Res res;
AVER(vmReturn != NULL);
/* sysconf code copied wholesale from vmso.c */
/* Find out the page size from the OS */
pagesize = sysconf(_SC_PAGESIZE);
/* check the actual returned pagesize will fit in an object of */
/* type Align. */
AVER(pagesize > 0);
AVER((unsigned long)pagesize <= (unsigned long)(Align)-1);
/* Note implicit conversion from "long" to "Align". */
align = pagesize;
AVER(SizeIsP2(align));
size = SizeAlignUp(size, align);
if((size == 0) || (size > (Size)(size_t)-1))
return ResRESOURCE;
/* Map in a page to store the descriptor on. */
addr = mmap(0, (size_t)SizeAlignUp(sizeof(VMStruct), align),
PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE,
-1, 0);
if(addr == MAP_FAILED) {
int e = errno;
AVER(e == ENOMEM); /* .assume.mmap.err */
return ResMEMORY;
}
vm = (VM)addr;
vm->align = align;
/* See .assume.not-last. */
addr = mmap(0, (size_t)size,
PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE,
-1, 0);
if(addr == MAP_FAILED) {
int e = errno;
AVER(e == ENOMEM); /* .assume.mmap.err */
res = ResRESOURCE;
goto failReserve;
}
vm->base = (Addr)addr;
vm->limit = AddrAdd(vm->base, size);
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;
failReserve:
(void)munmap((void *)vm, (size_t)SizeAlignUp(sizeof(VMStruct), align));
return res;
}
/* VMDestroy -- release all address space and destroy VM structure */
void VMDestroy(VM vm)
{
int r;
AVERT(VM, vm);
AVER(vm->mapped == (Size)0);
/* This appears to be pretty pointless, since the 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((void *)vm->base, (size_t)AddrOffset(vm->base, vm->limit));
AVER(r == 0);
r = munmap((void *)vm,
(size_t)SizeAlignUp(sizeof(VMStruct), vm->align));
AVER(r == 0);
EVENT_P(VMDestroy, vm);
}
/* VMBase -- return the base address of the memory reserved */
Addr VMBase(VM vm)
{
AVERT(VM, vm);
return vm->base;
}
/* VMLimit -- return the limit address of the memory reserved */
Addr VMLimit(VM vm)
{
AVERT(VM, vm);
return vm->limit;
}
/* VMReserved -- return the amount of memory reserved */
Size VMReserved(VM vm)
{
AVERT(VM, vm);
return vm->reserved;
}
/* VMMapped -- return the amount of memory actually mapped */
Size VMMapped(VM vm)
{
AVERT(VM, vm);
return vm->mapped;
}
/* VMMap -- map the given range of memory */
Res VMMap(VM vm, Addr base, Addr limit)
{
Size size;
AVERT(VM, vm);
AVER(sizeof(void *) == sizeof(Addr));
AVER(base < limit);
AVER(base >= vm->base);
AVER(limit <= vm->limit);
AVER(AddrIsAligned(base, vm->align));
AVER(AddrIsAligned(limit, vm->align));
size = AddrOffset(base, limit);
if(mmap((void *)base, (size_t)size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED,
-1, 0)
== MAP_FAILED) {
AVER(errno == ENOMEM); /* .assume.mmap.err */
return ResMEMORY;
}
vm->mapped += size;
EVENT_PAA(VMMap, vm, base, limit);
return ResOK;
}
/* VMUnmap -- unmap the given range of memory */
void VMUnmap(VM vm, Addr base, Addr limit)
{
Size size;
void *addr;
AVERT(VM, vm);
AVER(base < limit);
AVER(base >= vm->base);
AVER(limit <= vm->limit);
AVER(AddrIsAligned(base, vm->align));
AVER(AddrIsAligned(limit, vm->align));
AVER(sizeof(off_t) == sizeof(Size)); /* .assume.off_t */
size = AddrOffset(base, limit);
/* see <design/vmo1/#fun.unmap.offset> */
addr = mmap((void *)base, (size_t)size,
PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED,
-1, 0);
AVER(addr == (void *)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.
*/