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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copypage-v6.c (3380B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *  linux/arch/arm/mm/copypage-v6.c
      4 *
      5 *  Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
      6 */
      7#include <linux/init.h>
      8#include <linux/spinlock.h>
      9#include <linux/mm.h>
     10#include <linux/highmem.h>
     11#include <linux/pagemap.h>
     12
     13#include <asm/shmparam.h>
     14#include <asm/tlbflush.h>
     15#include <asm/cacheflush.h>
     16#include <asm/cachetype.h>
     17
     18#include "mm.h"
     19
     20#if SHMLBA > 16384
     21#error FIX ME
     22#endif
     23
     24static DEFINE_RAW_SPINLOCK(v6_lock);
     25
     26/*
     27 * Copy the user page.  No aliasing to deal with so we can just
     28 * attack the kernel's existing mapping of these pages.
     29 */
     30static void v6_copy_user_highpage_nonaliasing(struct page *to,
     31	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
     32{
     33	void *kto, *kfrom;
     34
     35	kfrom = kmap_atomic(from);
     36	kto = kmap_atomic(to);
     37	copy_page(kto, kfrom);
     38	kunmap_atomic(kto);
     39	kunmap_atomic(kfrom);
     40}
     41
     42/*
     43 * Clear the user page.  No aliasing to deal with so we can just
     44 * attack the kernel's existing mapping of this page.
     45 */
     46static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned long vaddr)
     47{
     48	void *kaddr = kmap_atomic(page);
     49	clear_page(kaddr);
     50	kunmap_atomic(kaddr);
     51}
     52
     53/*
     54 * Discard data in the kernel mapping for the new page.
     55 * FIXME: needs this MCRR to be supported.
     56 */
     57static void discard_old_kernel_data(void *kto)
     58{
     59	__asm__("mcrr	p15, 0, %1, %0, c6	@ 0xec401f06"
     60	   :
     61	   : "r" (kto),
     62	     "r" ((unsigned long)kto + PAGE_SIZE - 1)
     63	   : "cc");
     64}
     65
     66/*
     67 * Copy the page, taking account of the cache colour.
     68 */
     69static void v6_copy_user_highpage_aliasing(struct page *to,
     70	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
     71{
     72	unsigned int offset = CACHE_COLOUR(vaddr);
     73	unsigned long kfrom, kto;
     74
     75	if (!test_and_set_bit(PG_dcache_clean, &from->flags))
     76		__flush_dcache_page(page_mapping_file(from), from);
     77
     78	/* FIXME: not highmem safe */
     79	discard_old_kernel_data(page_address(to));
     80
     81	/*
     82	 * Now copy the page using the same cache colour as the
     83	 * pages ultimate destination.
     84	 */
     85	raw_spin_lock(&v6_lock);
     86
     87	kfrom = COPYPAGE_V6_FROM + (offset << PAGE_SHIFT);
     88	kto   = COPYPAGE_V6_TO + (offset << PAGE_SHIFT);
     89
     90	set_top_pte(kfrom, mk_pte(from, PAGE_KERNEL));
     91	set_top_pte(kto, mk_pte(to, PAGE_KERNEL));
     92
     93	copy_page((void *)kto, (void *)kfrom);
     94
     95	raw_spin_unlock(&v6_lock);
     96}
     97
     98/*
     99 * Clear the user page.  We need to deal with the aliasing issues,
    100 * so remap the kernel page into the same cache colour as the user
    101 * page.
    102 */
    103static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
    104{
    105	unsigned long to = COPYPAGE_V6_TO + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
    106
    107	/* FIXME: not highmem safe */
    108	discard_old_kernel_data(page_address(page));
    109
    110	/*
    111	 * Now clear the page using the same cache colour as
    112	 * the pages ultimate destination.
    113	 */
    114	raw_spin_lock(&v6_lock);
    115
    116	set_top_pte(to, mk_pte(page, PAGE_KERNEL));
    117	clear_page((void *)to);
    118
    119	raw_spin_unlock(&v6_lock);
    120}
    121
    122struct cpu_user_fns v6_user_fns __initdata = {
    123	.cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
    124	.cpu_copy_user_highpage	= v6_copy_user_highpage_nonaliasing,
    125};
    126
    127static int __init v6_userpage_init(void)
    128{
    129	if (cache_is_vipt_aliasing()) {
    130		cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
    131		cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
    132	}
    133
    134	return 0;
    135}
    136
    137core_initcall(v6_userpage_init);