unit-tests/test-cases/prebased-performance/foo.c

   1 /*
   2  * Copyright (c) 2006 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <stdbool.h>
  25 #include <stdint.h>
  26 #include <stdio.h>
  27 #include <sys/types.h>
  28 #include <unistd.h>
  29 #include <mach/mach.h>
  30
  31 struct page
  32 {
  33         struct page*    other;
  34         char                    pad[4096-sizeof(void*)];
  35 };
  36
  37
  38 struct page p1 = { &p1 };
  39 struct page p2 = { &p1 };
  40 struct page p3 = { &p1 };
  41 struct page p4 = { &p1 };
  42 struct page p5 = { &p1 };
  43 struct page p6 = { &p1 };
  44 struct page p7 = { &p1 };
  45 struct page p8 = { &p1 };
  46 struct page p9 = { &p1 };
  47 struct page p10 = { &p1 };
  48
  49 //
  50 // This dylib has 10 pages of data and each page will be adjusted
  51 // by dyld if this dylib is not loaded at its preferred address.
  52 //
  53 bool checkRebasing()
  54 {
  55         int dirtyPageCount = 0;
  56         vm_address_t start = (((uintptr_t)&p1) + 4095) & (-4096);
  57         vm_address_t end = (((uintptr_t)&p10) + 4095) & (-4096);
  58         task_port_t task;
  59         task_for_pid(mach_task_self(), getpid(), &task);
  60
  61         for (vm_address_t addr = start; addr < end; addr += 4096) {
  62                 integer_t disposition = 0;
  63                 integer_t ref_count = 0;
  64                 vm_map_page_query(task, start, &disposition, &ref_count);
  65                 if ( disposition & VM_PAGE_QUERY_PAGE_DIRTY )
  66                         ++dirtyPageCount;
  67         }
  68
  69         // if there are too many dirty pages, then dyld is inefficient
  70         return ( dirtyPageCount < 2 );
  71 }
  72
  73
  74
  75
  76