1 /* 2 * linux/arch/s390/mm/mmap.c 3 * 4 * flexible mmap layout support 5 * 6 * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. 7 * All Rights Reserved. 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU General Public License for more details. 18 * 19 * You should have received a copy of the GNU General Public License 20 * along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 * 23 * 24 * Started by Ingo Molnar <mingo@elte.hu> 25 */ 26 27 #include <linux/personality.h> 28 #include <linux/mm.h> 29 #include <linux/module.h> 30 #include <asm/pgalloc.h> 31 32 /* 33 * Top of mmap area (just below the process stack). 34 * 35 * Leave an at least ~128 MB hole. 36 */ 37 #define MIN_GAP (128*1024*1024) 38 #define MAX_GAP (TASK_SIZE/6*5) 39 40 static inline unsigned long mmap_base(void) 41 { 42 unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur; 43 44 if (gap < MIN_GAP) 45 gap = MIN_GAP; 46 else if (gap > MAX_GAP) 47 gap = MAX_GAP; 48 49 return TASK_SIZE - (gap & PAGE_MASK); 50 } 51 52 static inline int mmap_is_legacy(void) 53 { 54 #ifdef CONFIG_64BIT 55 /* 56 * Force standard allocation for 64 bit programs. 57 */ 58 if (!test_thread_flag(TIF_31BIT)) 59 return 1; 60 #endif 61 return sysctl_legacy_va_layout || 62 (current->personality & ADDR_COMPAT_LAYOUT) || 63 current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY; 64 } 65 66 #ifndef CONFIG_64BIT 67 68 /* 69 * This function, called very early during the creation of a new 70 * process VM image, sets up which VM layout function to use: 71 */ 72 void arch_pick_mmap_layout(struct mm_struct *mm) 73 { 74 /* 75 * Fall back to the standard layout if the personality 76 * bit is set, or if the expected stack growth is unlimited: 77 */ 78 if (mmap_is_legacy()) { 79 mm->mmap_base = TASK_UNMAPPED_BASE; 80 mm->get_unmapped_area = arch_get_unmapped_area; 81 mm->unmap_area = arch_unmap_area; 82 } else { 83 mm->mmap_base = mmap_base(); 84 mm->get_unmapped_area = arch_get_unmapped_area_topdown; 85 mm->unmap_area = arch_unmap_area_topdown; 86 } 87 } 88 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout); 89 90 #else 91 92 static unsigned long 93 s390_get_unmapped_area(struct file *filp, unsigned long addr, 94 unsigned long len, unsigned long pgoff, unsigned long flags) 95 { 96 struct mm_struct *mm = current->mm; 97 int rc; 98 99 addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags); 100 if (addr & ~PAGE_MASK) 101 return addr; 102 if (unlikely(mm->context.asce_limit < addr + len)) { 103 rc = crst_table_upgrade(mm, addr + len); 104 if (rc) 105 return (unsigned long) rc; 106 } 107 return addr; 108 } 109 110 static unsigned long 111 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 112 const unsigned long len, const unsigned long pgoff, 113 const unsigned long flags) 114 { 115 struct mm_struct *mm = current->mm; 116 unsigned long addr = addr0; 117 int rc; 118 119 addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); 120 if (addr & ~PAGE_MASK) 121 return addr; 122 if (unlikely(mm->context.asce_limit < addr + len)) { 123 rc = crst_table_upgrade(mm, addr + len); 124 if (rc) 125 return (unsigned long) rc; 126 } 127 return addr; 128 } 129 /* 130 * This function, called very early during the creation of a new 131 * process VM image, sets up which VM layout function to use: 132 */ 133 void arch_pick_mmap_layout(struct mm_struct *mm) 134 { 135 /* 136 * Fall back to the standard layout if the personality 137 * bit is set, or if the expected stack growth is unlimited: 138 */ 139 if (mmap_is_legacy()) { 140 mm->mmap_base = TASK_UNMAPPED_BASE; 141 mm->get_unmapped_area = s390_get_unmapped_area; 142 mm->unmap_area = arch_unmap_area; 143 } else { 144 mm->mmap_base = mmap_base(); 145 mm->get_unmapped_area = s390_get_unmapped_area_topdown; 146 mm->unmap_area = arch_unmap_area_topdown; 147 } 148 } 149 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout); 150 151 #endif 152