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Viewing changes to arch/mips/mm/mmap.c

  • Committer: Bazaar Package Importer
  • Author(s): Paolo Pisati
  • Date: 2011-06-29 15:23:51 UTC
  • mfrom: (26.1.1 natty-proposed)
  • Revision ID: james.westby@ubuntu.com-20110629152351-xs96tm303d95rpbk
Tags: 3.0.0-1200.2
* Rebased against 3.0.0-6.7
* BSP from TI based on 3.0.0

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arch/mips/mm/mmap.c
 
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/*
 
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 * This file is subject to the terms and conditions of the GNU General Public
 
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 * License.  See the file "COPYING" in the main directory of this archive
 
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 * for more details.
 
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 *
 
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 * Copyright (C) 2011 Wind River Systems,
 
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 *   written by Ralf Baechle <ralf@linux-mips.org>
 
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 */
 
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#include <linux/errno.h>
 
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#include <linux/mm.h>
 
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#include <linux/mman.h>
 
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#include <linux/module.h>
 
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#include <linux/random.h>
 
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#include <linux/sched.h>
 
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unsigned long shm_align_mask = PAGE_SIZE - 1;   /* Sane caches */
 
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EXPORT_SYMBOL(shm_align_mask);
 
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#define COLOUR_ALIGN(addr,pgoff)                                \
 
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        ((((addr) + shm_align_mask) & ~shm_align_mask) +        \
 
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         (((pgoff) << PAGE_SHIFT) & shm_align_mask))
 
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unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
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        unsigned long len, unsigned long pgoff, unsigned long flags)
 
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{
 
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        struct vm_area_struct * vmm;
 
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        int do_color_align;
 
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        if (len > TASK_SIZE)
 
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                return -ENOMEM;
 
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        if (flags & MAP_FIXED) {
 
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                /* Even MAP_FIXED mappings must reside within TASK_SIZE.  */
 
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                if (TASK_SIZE - len < addr)
 
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                        return -EINVAL;
 
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                /*
 
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                 * We do not accept a shared mapping if it would violate
 
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                 * cache aliasing constraints.
 
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                 */
 
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                if ((flags & MAP_SHARED) &&
 
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                    ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
 
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                        return -EINVAL;
 
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                return addr;
 
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        }
 
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        do_color_align = 0;
 
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        if (filp || (flags & MAP_SHARED))
 
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                do_color_align = 1;
 
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        if (addr) {
 
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                if (do_color_align)
 
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                        addr = COLOUR_ALIGN(addr, pgoff);
 
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                else
 
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                        addr = PAGE_ALIGN(addr);
 
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                vmm = find_vma(current->mm, addr);
 
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                if (TASK_SIZE - len >= addr &&
 
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                    (!vmm || addr + len <= vmm->vm_start))
 
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                        return addr;
 
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        }
 
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        addr = current->mm->mmap_base;
 
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        if (do_color_align)
 
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                addr = COLOUR_ALIGN(addr, pgoff);
 
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        else
 
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                addr = PAGE_ALIGN(addr);
 
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        for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
 
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                /* At this point:  (!vmm || addr < vmm->vm_end). */
 
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                if (TASK_SIZE - len < addr)
 
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                        return -ENOMEM;
 
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                if (!vmm || addr + len <= vmm->vm_start)
 
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                        return addr;
 
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                addr = vmm->vm_end;
 
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                if (do_color_align)
 
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                        addr = COLOUR_ALIGN(addr, pgoff);
 
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        }
 
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}
 
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void arch_pick_mmap_layout(struct mm_struct *mm)
 
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{
 
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        unsigned long random_factor = 0UL;
 
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        if (current->flags & PF_RANDOMIZE) {
 
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                random_factor = get_random_int();
 
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                random_factor = random_factor << PAGE_SHIFT;
 
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                if (TASK_IS_32BIT_ADDR)
 
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                        random_factor &= 0xfffffful;
 
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                else
 
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                        random_factor &= 0xffffffful;
 
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        }
 
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        mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
 
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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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static inline unsigned long brk_rnd(void)
 
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{
 
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        unsigned long rnd = get_random_int();
 
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        rnd = rnd << PAGE_SHIFT;
 
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        /* 8MB for 32bit, 256MB for 64bit */
 
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        if (TASK_IS_32BIT_ADDR)
 
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                rnd = rnd & 0x7ffffful;
 
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        else
 
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                rnd = rnd & 0xffffffful;
 
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        return rnd;
 
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}
 
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unsigned long arch_randomize_brk(struct mm_struct *mm)
 
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{
 
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        unsigned long base = mm->brk;
 
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        unsigned long ret;
 
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        ret = PAGE_ALIGN(base + brk_rnd());
 
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        if (ret < mm->brk)
 
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                return mm->brk;
 
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        return ret;
 
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}