[PATCH] x86_64: Bring x86-64 ia32 emul in sync with i386 on READ_IMPLIES_EXEC enabling

Currently ia32 binaries behave differently with respect to enabling
READ_IMPLIES_EXEC.  On i386 a binary with the exec_stack flag set is
executed with READ_IMPLIES_EXEC enabled as well.  The same binary
executes without READ_IMPLIES_EXEC on x86-64.

This causes binaries that work on i386 to fail on x86-64 which goes
somewhat against the whole 32 bit emulation idea.

It has been argued that READ_IMPLIES_EXEC should not be enabled at all
for binaries that have the exec_stack flag.  Which is probably a valid
point.  However until this is clarified I think x86-64 should behave the
same for ia32 binaries as i386.

The following patch brings x86-64 in sync with i386 for ia32 binaries.
Signed-off-by: Markus Schoder <lists@gammarayburst.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/ia32/ia32_binfmt.c

@@ -182,7 +182,7 @@ struct elf_prpsinfo
 #define user user32
 
 #define __ASM_X86_64_ELF_H 1
-#define elf_read_implies_exec(ex, have_pt_gnu_stack)	(!(have_pt_gnu_stack))
+#define elf_read_implies_exec(ex, executable_stack)     (executable_stack != EXSTACK_DISABLE_X)
 //#include <asm/ia32.h>
 #include <linux/elf.h>