1 // SPDX-License-Identifier: GPL-2.0-or-later
3  *  flexible mmap layout support
5  * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
16 #include <linux/elf-randomize.h>
30 	if (current->personality & ADDR_COMPAT_LAYOUT)  in mmap_is_legacy()
33 	if (rlim_stack->rlim_cur == RLIM_INFINITY)  in mmap_is_legacy()
55 	if (!(current->flags & PF_RANDOMIZE))  in stack_maxrandom_size()
68 	unsigned long gap = rlim_stack->rlim_cur;  in mmap_base()
80 	return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);  in mmap_base()
94 	struct mm_struct *mm = current->mm;  in radix__arch_get_unmapped_area()
96 	int fixed = (flags & MAP_FIXED);  in radix__arch_get_unmapped_area()  local
101 	if (addr >= high_limit || (fixed && (addr + len > high_limit)))  in radix__arch_get_unmapped_area()
105 		return -ENOMEM;  in radix__arch_get_unmapped_area()
107 	if (fixed) {  in radix__arch_get_unmapped_area()
108 		if (addr > high_limit - len)  in radix__arch_get_unmapped_area()
109 			return -ENOMEM;  in radix__arch_get_unmapped_area()
116 		if (high_limit - len >= addr && addr >= mmap_min_addr &&  in radix__arch_get_unmapped_area()
123 	info.low_limit = mm->mmap_base;  in radix__arch_get_unmapped_area()
138 	struct mm_struct *mm = current->mm;  in radix__arch_get_unmapped_area_topdown()
140 	int fixed = (flags & MAP_FIXED);  in radix__arch_get_unmapped_area_topdown()  local
145 	if (addr >= high_limit || (fixed && (addr + len > high_limit)))  in radix__arch_get_unmapped_area_topdown()
149 		return -ENOMEM;  in radix__arch_get_unmapped_area_topdown()
151 	if (fixed) {  in radix__arch_get_unmapped_area_topdown()
152 		if (addr > high_limit - len)  in radix__arch_get_unmapped_area_topdown()
153 			return -ENOMEM;  in radix__arch_get_unmapped_area_topdown()
160 		if (high_limit - len >= addr && addr >= mmap_min_addr &&  in radix__arch_get_unmapped_area_topdown()
168 	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);  in radix__arch_get_unmapped_area_topdown()
174 	VM_BUG_ON(addr != -ENOMEM);  in radix__arch_get_unmapped_area_topdown()
178 	 * so fall back to the bottom-up function here. This scenario  in radix__arch_get_unmapped_area_topdown()
190 		mm->mmap_base = TASK_UNMAPPED_BASE;  in radix__arch_pick_mmap_layout()
191 		mm->get_unmapped_area = radix__arch_get_unmapped_area;  in radix__arch_pick_mmap_layout()
193 		mm->mmap_base = mmap_base(random_factor, rlim_stack);  in radix__arch_pick_mmap_layout()
194 		mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;  in radix__arch_pick_mmap_layout()
205  * process VM image, sets up which VM layout function to use:
211 	if (current->flags & PF_RANDOMIZE)  in arch_pick_mmap_layout()
218 	 * Fall back to the standard layout if the personality  in arch_pick_mmap_layout()
222 		mm->mmap_base = TASK_UNMAPPED_BASE;  in arch_pick_mmap_layout()
223 		mm->get_unmapped_area = arch_get_unmapped_area;  in arch_pick_mmap_layout()
225 		mm->mmap_base = mmap_base(random_factor, rlim_stack);  in arch_pick_mmap_layout()
226 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;  in arch_pick_mmap_layout()