cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mmap.c (1757B)

      1// SPDX-License-Identifier: GPL-2.0
      2// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
      3
      4#include <linux/fs.h>
      5#include <linux/mm.h>
      6#include <linux/mman.h>
      7#include <linux/shm.h>
      8#include <linux/sched.h>
      9#include <linux/random.h>
     10#include <linux/io.h>
     11
     12#define COLOUR_ALIGN(addr,pgoff)		\
     13	((((addr)+SHMLBA-1)&~(SHMLBA-1)) +	\
     14	 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
     15
     16/*
     17 * We need to ensure that shared mappings are correctly aligned to
     18 * avoid aliasing issues with VIPT caches.  We need to ensure that
     19 * a specific page of an object is always mapped at a multiple of
     20 * SHMLBA bytes.
     21 *
     22 * We unconditionally provide this function for all cases.
     23 */
     24unsigned long
     25arch_get_unmapped_area(struct file *filp, unsigned long addr,
     26		unsigned long len, unsigned long pgoff, unsigned long flags)
     27{
     28	struct mm_struct *mm = current->mm;
     29	struct vm_area_struct *vma;
     30	int do_align = 0;
     31	struct vm_unmapped_area_info info;
     32
     33	/*
     34	 * We only need to do colour alignment if either the I or D
     35	 * caches alias.
     36	 */
     37	do_align = filp || (flags & MAP_SHARED);
     38
     39	/*
     40	 * We enforce the MAP_FIXED case.
     41	 */
     42	if (flags & MAP_FIXED) {
     43		if (flags & MAP_SHARED &&
     44		    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
     45			return -EINVAL;
     46		return addr;
     47	}
     48
     49	if (len > TASK_SIZE)
     50		return -ENOMEM;
     51
     52	if (addr) {
     53		if (do_align)
     54			addr = COLOUR_ALIGN(addr, pgoff);
     55		else
     56			addr = PAGE_ALIGN(addr);
     57
     58		vma = find_vma(mm, addr);
     59		if (TASK_SIZE - len >= addr &&
     60		    (!vma || addr + len <= vm_start_gap(vma)))
     61			return addr;
     62	}
     63
     64	info.flags = 0;
     65	info.length = len;
     66	info.low_limit = mm->mmap_base;
     67	info.high_limit = TASK_SIZE;
     68	info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
     69	info.align_offset = pgoff << PAGE_SHIFT;
     70	return vm_unmapped_area(&info);
     71}