[PATCH] Windows implementation of enable_execute_stack

[Ruben Van Boxem]

2013/5/25 Aaron Ballman <aaron at aaronballman.com>

> On Fri, May 24, 2013 at 5:53 PM, Ruben Van Boxem
> <vanboxem.ruben at gmail.com> wrote:
> > Hi,
> >
> > I submitted this patch a long while ago, together with a bunch of other
> > changes (some of which got applied back then).
> >
> > If compiler-rt is in the LLVM tree, a Windows build chokes on this little
> > bit.
> >
> > The relevant test passed back then, but I can't check this right now, as
> > LLVM is being difficult (some errors I need to figure out) and
> compiler-rt
> > has since moved to be a subproject requiring the LLVM tree to be built.
> >
> >
> > Please comment or apply. Thanks!
> >
> > Ruben
> >
> > PS: I'm not subscribed, please keep me in the CC list
> >
> > Index: lib/enable_execute_stack.c
> > ===================================================================
> > --- lib/enable_execute_stack.c (revision 182667)
> > +++ lib/enable_execute_stack.c (working copy)
> > @@ -10,7 +10,11 @@
> >
> >  #include "int_lib.h"
> >
> > +#ifndef _WIN32
> >  #include <sys/mman.h>
> > +#else
> > +#include <windows.h>
> > +#endif
> >
> >  /* #include "config.h"
> >   * FIXME: CMake - include when cmake system is ready.
> > @@ -38,7 +42,7 @@
> >
> >  void __enable_execute_stack(void* addr)
> >  {
> > -
> > +#ifndef _WIN32
> >  #if __APPLE__
> >   /* On Darwin, pagesize is always 4096 bytes */
> >   const uintptr_t pageSize = 4096;
> > @@ -54,6 +58,14 @@
> >   unsigned char* endPage = (unsigned char*)((p+TRAMPOLINE_SIZE+pageSize)
> & pageAlignMask);
> >   size_t length = endPage - startPage;
> >   (void) mprotect((void *)startPage, length, PROT_READ | PROT_WRITE |
> PROT_EXEC);
> > +#else
>
> Why not simply #elif defined(_WIN32) and skip the extra level of #ifs?
>

There is an #if __APPLE__ for this part:
#if __APPLE__
    /* On Darwin, pagesize is always 4096 bytes */
    const uintptr_t pageSize = 4096;
#elif !defined(HAVE_SYSCONF)
#error "HAVE_SYSCONF not defined! See enable_execute_stack.c"
#else
        const uintptr_t pageSize = sysconf(_SC_PAGESIZE);
#endif /* __APPLE__ */

followed by the generic Unix implementation. Neither applies to Win32, so I
ifdef'ed the whole thing.


> > +    MEMORY_BASIC_INFORMATION b;
> > +
> > +    if (!VirtualQuery(addr, &b, sizeof(b)))
> > +     exit(1);
> > +   if (!VirtualProtect(b.BaseAddress, b.RegionSize,
> PAGE_EXECUTE_READWRITE, &b.Protect))
> > +     exit(1);
> > +#endif /* _WIN32 */
> >  }
>
> Aside from that, patch LGTM.
>

Great!

Ruben


>
> ~Aaron
>
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