8817210d4d
Another try at this. For 32bit follow the 32bit implementation from Ingo - mappings are growing down from the end of stack now and vary randomly by 1GB. Randomized mappings for 64bit just vary the normal mmap break by 1TB. I didn't bother implementing full flex mmap for 64bit because it shouldn't be needed there. Cc: mingo@elte.hu Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
31 lines
893 B
C
31 lines
893 B
C
/* Copyright 2005 Andi Kleen, SuSE Labs.
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* Licensed under GPL, v.2
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*/
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#include <linux/config.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/random.h>
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#include <asm/ia32.h>
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/* Notebook: move the mmap code from sys_x86_64.c over here. */
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void arch_pick_mmap_layout(struct mm_struct *mm)
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{
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#ifdef CONFIG_IA32_EMULATION
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if (current_thread_info()->flags & _TIF_IA32)
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return ia32_pick_mmap_layout(mm);
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#endif
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mm->mmap_base = TASK_UNMAPPED_BASE;
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if (current->flags & PF_RANDOMIZE) {
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/* Add 28bit randomness which is about 40bits of address space
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because mmap base has to be page aligned.
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or ~1/128 of the total user VM
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(total user address space is 47bits) */
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unsigned rnd = get_random_int() & 0xfffffff;
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mm->mmap_base += ((unsigned long)rnd) << PAGE_SHIFT;
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}
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mm->get_unmapped_area = arch_get_unmapped_area;
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mm->unmap_area = arch_unmap_area;
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}
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