Re: FreeBSD and wine mmap

On Tue, Aug 10, 2004 at 01:53:14PM -0400, Anish Mistry wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
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> On Wednesday 04 August 2004 06:39 pm, you wrote:
> > On Wed, Aug 04, 2004 at 06:28:02PM -0400, Anish Mistry wrote:
> > > Ok, so we need something like vm_map_findspace(), but for process address
> > > mapping?  ie. pmap_findspace() that will return an address to a large
> > > enough free chunk?
> >
> > That's a good start, just to get something to work with. How this fits in
> > with the vm code and whether it is ultimately suitable in the long run is
> > probably up to Alan Cox. For now, just get something that (a) doesn't break
> > anything else; and (b) lets Wine behave the way it needs to.
> >
> > AFAIK, there are still pthread issues with Wine, but those can't be
> > addressed until the mmap issue has a work-around.
> I've got a small patch that gets by the initial problem about not being to 
> mmap the memory for the libraries, but the addresses that are mmap'ed seem to 
> seem to overlap with memory that the current pthread implementation want to 
> mmap for the "red zone" when wine tries to create a thread.  It can't mmap 
> the "red zone" addresses since all those address mapping where gobbled up 
> before the thread launched.
> I'll try to figure out a way to maybe leave a space for the "red zone" and see 
> if that works.
> Someone who actually knows what they are doing should probably take a look.

The red pages are implemented by leaving the memory space unallocated;
I don't like that one bit -- this will cause those spaces to be allocated
but given no protection, which should provide the crash feature that the
guard pages are there for, but be less bogus (and it doesn't use more
"memory," but it will use a few more vm_map_entrys.

Index: lib/libpthread/thread/thr_stack.c
===================================================================
RCS file: /usr/ncvs/src/lib/libpthread/thread/thr_stack.c,v
retrieving revision 1.8
diff -u -r1.8 thr_stack.c
--- lib/libpthread/thread/thr_stack.c	14 Sep 2003 22:39:44 -0000	1.8
+++ lib/libpthread/thread/thr_stack.c	29 Aug 2004 04:50:28 -0000
_at__at_ -214,6 +214,17 _at__at_
 		     stacksize, PROT_READ | PROT_WRITE, MAP_STACK,
 		     -1, 0)) == MAP_FAILED)
 			attr->stackaddr_attr = NULL;
+		if (attr->stackaddr_attr != NULL) {
+			void *red;
+
+			red = mmap((char *)attr->stackaddr_attr + stacksize,
+			    _thr_guard_default, PROT_NONE,
+			    MAP_ANON | MAP_FIXED | MAP_PRIVATE, -1, 0);
+			if (red == MAP_FAILED) {
+				(void)munmap(attr->stackaddr_attr, stacksize);
+				attr->stackaddr_attr = NULL;
+			}
+		}
 	}
 	if (attr->stackaddr_attr != NULL)
 		return (0);

-- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green_at_FreeBSD.org                               \  The Power to Serve! \
 Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\