Re: [Qemu-devel] [PATCH] fix interaction with noexecstack

[Filip Navara]

Fabrice Bellard wrote:

> The patch seems OK for me, at least until the instruction cache is 
> dynamically allocated.

I haven't tried the patch, but there isn't any "mprotect" function on 
Windows so I guess it would break MinGW builds. See the code below. It 
should work, but *I HAVEN'T TESTED IT*:

Regards,
Filip

> Lennert Buytenhek wrote:

[snip]

> > --- qemu-20040804.orig/exec.c    2004-07-06 02:00:18.000000000 +0300
> > +++ qemu-20040804.test/exec.c    2004-09-04 02:49:25.414945456 +0300
> > @@ -127,6 +127,9 @@
> >  
> >  static void page_init(void)
> >  {
> > +    unsigned long address;
> > +    unsigned long length;
#ifdef _WIN32
  DWORD old_protect;
#endif

> > +
> >      /* NOTE: we can always suppose that qemu_host_page_size >=
> >         TARGET_PAGE_SIZE */
> >  #ifdef _WIN32
> > @@ -134,6 +137,17 @@
> >  #else
> >      qemu_real_host_page_size = getpagesize();
> >  #endif
> > +
> > +    address = (unsigned long)code_gen_buffer;
> > +    address &= ~(qemu_real_host_page_size - 1);
> > +
> > +    length = (unsigned long)code_gen_buffer + sizeof(code_gen_buffer);
> > +    length -= address;
> > +    length += qemu_real_host_page_size - 1;
> > +    length &= ~(qemu_real_host_page_size - 1);
> > +
#ifdef _WIN32
*   *VirtualProtect(address, length, PAGE_EXECUTE_READWRITE, &old_protect);
#else

> > +    mprotect(address, length, PROT_READ | PROT_WRITE | PROT_EXEC);
#endif

> > +
> >      if (qemu_host_page_size == 0)
> >          qemu_host_page_size = qemu_real_host_page_size;
> >      if (qemu_host_page_size < TARGET_PAGE_SIZE)