5bba49f539
Enforce congruency of userspace shared mappings Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/*
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* ARC700 mmap
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*
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* (started from arm version - for VIPT alias handling)
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*
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* Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/sched.h>
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#include <asm/cacheflush.h>
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#define COLOUR_ALIGN(addr, pgoff) \
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((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) + \
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(((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
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/*
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* Ensure that shared mappings are correctly aligned to
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* avoid aliasing issues with VIPT caches.
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* We need to ensure that
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* a specific page of an object is always mapped at a multiple of
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* SHMLBA bytes.
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*/
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unsigned long
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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 mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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int do_align = 0;
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int aliasing = cache_is_vipt_aliasing();
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struct vm_unmapped_area_info info;
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/*
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* We only need to do colour alignment if D cache aliases.
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*/
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if (aliasing)
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do_align = filp || (flags & MAP_SHARED);
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/*
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* We enforce the MAP_FIXED case.
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*/
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if (flags & MAP_FIXED) {
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if (aliasing && flags & MAP_SHARED &&
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(addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
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return -EINVAL;
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return addr;
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}
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if (len > TASK_SIZE)
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return -ENOMEM;
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if (addr) {
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if (do_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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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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(!vma || addr + len <= vma->vm_start))
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return addr;
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}
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info.flags = 0;
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info.length = len;
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info.low_limit = mm->mmap_base;
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info.high_limit = TASK_SIZE;
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info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
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info.align_offset = pgoff << PAGE_SHIFT;
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return vm_unmapped_area(&info);
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}
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