[commit: ghc] master: Fix segfaults on SELinux machines; fixes #7629 (27cf625)

[Ian Lynagh]

Repository : http://darcs.haskell.org/ghc.git/

On branch  : master

https://github.com/ghc/ghc/commit/27cf625ab871f34434d9fe86cecf85a31f73f0e5

>---------------------------------------------------------------

commit 27cf625ab871f34434d9fe86cecf85a31f73f0e5
Author: Ian Lynagh <ian at well-typed.com>
Date:   Tue Apr 9 13:53:28 2013 +0100

    Fix segfaults on SELinux machines; fixes #7629
    
    Patch from wgmitchener.
    
    From the ticket:
    The two addresses (adjustorStub and code) contain the same memory
    (double-mapped), but one is writable while the other is executable.
    This is how libffi works around the SELinux restrictions. On
    non-SELinux systems the code and data addresses are probably the same.

>---------------------------------------------------------------

 rts/Adjustor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rts/Adjustor.c b/rts/Adjustor.c
index 1a0bc28..fbf95df 100644
--- a/rts/Adjustor.c
+++ b/rts/Adjustor.c
@@ -389,7 +389,7 @@ createAdjustor(int cconv, StgStablePtr hptr,
         int sz = totalArgumentSize(typeString);
         
         adjustorStub->call[0] = 0xe8;
-        *(long*)&adjustorStub->call[1] = ((char*)&adjustorCode) - ((char*)adjustorStub + 5);
+        *(long*)&adjustorStub->call[1] = ((char*)&adjustorCode) - ((char*)code + 5);
         adjustorStub->hptr = hptr;
         adjustorStub->wptr = wptr;