Avoid page_set_flags() assert in qemu-user host page protection code

V2 that uses endaddr = end-of-guest-address-space if !h2g_valid(endaddr)
after I found out that indeed works; and also disables the FreeBSD 6.x
/compat/linux/proc/self/maps fallback because it can return partial lines
if (at least I think that's the reason) the mappings change between
subsequent read() calls.
Signed-off-by: NJuergen Lock <nox@jelal.kn-bremen.de>
Acked-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

exec.c

@@ -307,13 +307,14 @@ static void page_init(void)
 
                     if (h2g_valid(endaddr)) {
                         endaddr = h2g(endaddr);
-                        page_set_flags(startaddr, endaddr, PAGE_RESERVED);
                     } else {
 #if TARGET_ABI_BITS <= L1_MAP_ADDR_SPACE_BITS
                         endaddr = ~0ul;
-                        page_set_flags(startaddr, endaddr, PAGE_RESERVED);
+#else
+                        endaddr = ((abi_ulong)1 << L1_MAP_ADDR_SPACE_BITS) - 1;
 #endif
                     }
+                    page_set_flags(startaddr, endaddr, PAGE_RESERVED);
                 }
             }
             free(freep);
@@ -324,11 +325,7 @@ static void page_init(void)
 
         last_brk = (unsigned long)sbrk(0);
 
-#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
-        f = fopen("/compat/linux/proc/self/maps", "r");
-#else
         f = fopen("/proc/self/maps", "r");
-#endif
         if (f) {
             mmap_lock();
 
@@ -344,7 +341,11 @@ static void page_init(void)
                     if (h2g_valid(endaddr)) {
                         endaddr = h2g(endaddr);
                     } else {
+#if TARGET_ABI_BITS <= L1_MAP_ADDR_SPACE_BITS
                         endaddr = ~0ul;
+#else
+                        endaddr = ((abi_ulong)1 << L1_MAP_ADDR_SPACE_BITS) - 1;
+#endif
                     }
                     page_set_flags(startaddr, endaddr, PAGE_RESERVED);
                 }