1 // SPDX-License-Identifier: GPL-2.0-or-later
8  * Copyright 2003-2009 Red Hat Inc.
21 #include <linux/elf-randomize.h>
28 	.flags = -1,
44 	if (current->flags & PF_RANDOMIZE) {  in stack_maxrandom_size()
45 		max = (-1UL) & __STACK_RND_MASK(task_size == task_size_32bit());  in stack_maxrandom_size()
64 	if (current->personality & ADDR_COMPAT_LAYOUT)  in mmap_is_legacy()
65 		return 1;  in mmap_is_legacy()
72 	if (!(current->flags & PF_RANDOMIZE))  in arch_rnd()
74 	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;  in arch_rnd()
85 	unsigned long gap = rlim_stack->rlim_cur;  in mmap_base()
105 	return PAGE_ALIGN(task_size - gap - rnd);  in mmap_base()
132 		clear_bit(MMF_TOPDOWN, &mm->flags);  in arch_pick_mmap_layout()
134 		set_bit(MMF_TOPDOWN, &mm->flags);  in arch_pick_mmap_layout()
136 	arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base,  in arch_pick_mmap_layout()
143 	 * syscall type (64-bit or compat). This applies for 64bit  in arch_pick_mmap_layout()
147 	arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base,  in arch_pick_mmap_layout()
155 	struct mm_struct *mm = current->mm;  in get_mmap_base()
159 		return is_legacy ? mm->mmap_compat_legacy_base  in get_mmap_base()
160 				 : mm->mmap_compat_base;  in get_mmap_base()
163 	return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;  in get_mmap_base()
167  * mmap_address_hint_valid - Validate the address hint of mmap
175  * On 64bit with 5-level page tables another sanity check is required
176  * because mappings requested by mmap(@addr, 0) which cross the 47-bit
180  *  is below the border of the 47-bit address space and @addr + @len is
183  *  With 4-level paging this request succeeds, but the resulting mapping
184  *  address will always be within the 47-bit virtual address space, because
187  *  addresses above 47-bit work correctly.
189  *  With 5-level paging this request would be granted and result in a
190  *  mapping which crosses the border of the 47-bit virtual address
191  *  space. If the application cannot handle addresses above 47-bit this
195  * the 47-bit virtual address boundary.
198  * different. The request with @addr < 47-bit and @addr + @len > 47-bit
199  * fails on a 4-level paging machine but succeeds on a 5-level paging
206 	if (TASK_SIZE - len < addr)  in mmap_address_hint_valid()
215 	return addr + count - 1 <= __pa(high_memory - 1);  in valid_phys_addr_range()
223 	return phys_addr_valid(addr + count - 1);  in valid_mmap_phys_addr_range()