Revert "[mmalloc] Use mremap to expand heaps (heap collision prevention)"

This is really how is should be handled. However, this does not work
if someone has split the VMA in parts: this is done when creating
stacks on the heap without MC, mprotect() is used to create a guard
page for the stack.

This reverts commit ba3185d8a4f0a56804d3b1ff24e596096f06a37c.

diff --git a/src/xbt/mmalloc/mmorecore.c b/src/xbt/mmalloc/mmorecore.c
index f47c539..9fbf7a9 100644 (file)
--- a/src/xbt/mmalloc/mmorecore.c
+++ b/src/xbt/mmalloc/mmorecore.c
@@ -109,14 +109,9 @@ void *mmorecore(struct mdesc *mdp, ssize_t size)
 
       /* Let's call mmap. Note that it is possible that mdp->top
          is 0. In this case mmap will choose the address for us */
 
       /* Let's call mmap. Note that it is possible that mdp->top
          is 0. In this case mmap will choose the address for us */

-      if(mdp->base==mdp->top)
-        mapto = mmap(mdp->top, mapbytes, PROT_READ | PROT_WRITE,
+      mapto = mmap(mdp->top, mapbytes, PROT_READ | PROT_WRITE,

                    MAP_PRIVATE_OR_SHARED(mdp) | MAP_IS_ANONYMOUS(mdp) |
                    MAP_FIXED, MAP_ANON_OR_FD(mdp), foffset);
                    MAP_PRIVATE_OR_SHARED(mdp) | MAP_IS_ANONYMOUS(mdp) |
                    MAP_FIXED, MAP_ANON_OR_FD(mdp), foffset);

-      else {
-        size_t old_size = (char*)mdp->top - (char*)mdp->base;
-        mapto = mremap(mdp->base, old_size, old_size+size, 0);
-      }

 
       if (mapto == (void *) -1/* That's MAP_FAILED */) {
         char buff[1024];
 
       if (mapto == (void *) -1/* That's MAP_FAILED */) {
         char buff[1024];


@@ -129,6 +124,9 @@ void *mmorecore(struct mdesc *mdp, ssize_t size)
         abort();
       }
 
         abort();
       }
 

+      if (mdp->top == 0)
+        mdp->base = mdp->breakval = mapto;
+

       mdp->top = PAGE_ALIGN((char *) mdp->breakval + size);
       result = (void *) mdp->breakval;
       mdp->breakval = (char *) mdp->breakval + size;
       mdp->top = PAGE_ALIGN((char *) mdp->breakval + size);
       result = (void *) mdp->breakval;
       mdp->breakval = (char *) mdp->breakval + size;