Hello. This bug is a result of a slip-up on my part. Attached is a fix for your it. You can apply this to the GHC-6.4.1 source code and compile it for yourself (or apply it to the Debian package too and dpkg-buildpackage, I guess).
Cheers.
Index: Linker.c
===================================================================
RCS file: /home/cvs/root/fptools/ghc/rts/Linker.c,v
retrieving revision 1.208
diff -u -p -r1.208 Linker.c
--- Linker.c 28 Oct 2005 08:10:09 -0000 1.208
+++ Linker.c 15 Dec 2005 21:41:09 -0000
@@ -1447,22 +1447,37 @@ static int ocAllocateJumpIslands( Object
n = ROUND_UP( oc->fileSize, pagesize );
m = ROUND_UP( aligned + sizeof (ppcJumpIsland) * count, pagesize );
- /* The effect of this mremap() call is only the ensure that we have
- * a sufficient number of virtually contiguous pages. As returned from
- * mremap, the pages past the end of the file are not backed. We give
- * them a backing by using MAP_FIXED to map in anonymous pages.
+ /* If we have a half-page-size file and map one page of it then
+ * the part of the page after the size of the file remains accessible.
+ * If, however, we map in 2 pages, the 2nd page is not accessible
+ * and will give a "Bus Error" on access. To get around this, we check
+ * if we need any extra pages for the jump islands and map them in
+ * anonymously. We must check that we actually require extra pages
+ * otherwise the attempt to mmap 0 pages of anonymous memory will
+ * fail -EINVAL.
*/
- if( (oc->image = mremap( oc->image, n, m, MREMAP_MAYMOVE )) == MAP_FAILED )
- {
- errorBelch( "Unable to mremap for Jump Islands\n" );
- return 0;
- }
- if( mmap( oc->image + n, m - n, PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, 0, 0 ) == MAP_FAILED )
+ if( m > n )
{
- errorBelch( "Unable to mmap( MAP_FIXED ) for Jump Islands\n" );
- return 0;
+ /* The effect of this mremap() call is only the ensure that we have
+ * a sufficient number of virtually contiguous pages. As returned from
+ * mremap, the pages past the end of the file are not backed. We give
+ * them a backing by using MAP_FIXED to map in anonymous pages.
+ */
+ oc->image = mremap( oc->image, n, m, MREMAP_MAYMOVE );
+
+ if( oc->image == MAP_FAILED )
+ {
+ errorBelch( "Unable to mremap for Jump Islands\n" );
+ return 0;
+ }
+
+ if( mmap( oc->image + n, m - n, PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, 0, 0 ) == MAP_FAILED )
+ {
+ errorBelch( "Unable to mmap( MAP_FIXED ) for Jump Islands\n" );
+ return 0;
+ }
}
#else
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