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 31struct page 32{ 33 struct page* other; 34 char pad[4096-sizeof(void*)]; 35}; 36 37 38struct page p1 = { &p1 }; 39struct page p2 = { &p1 }; 40struct page p3 = { &p1 }; 41struct page p4 = { &p1 }; 42struct page p5 = { &p1 }; 43struct page p6 = { &p1 }; 44struct page p7 = { &p1 }; 45struct page p8 = { &p1 }; 46struct page p9 = { &p1 }; 47struct 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// 53bool 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 //fprintf(stderr, "dirtyPageCount=%d\n", dirtyPageCount); 70 71 // if there are too many dirty pages, then dyld is inefficient 72 return ( dirtyPageCount < 2 ); 73} 74 75 76 77 78 79