linux-stable/arch/arm/mm/copypage-v6.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/mm/copypage-v6.c
*
* Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
*/
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <asm/shmparam.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/cachetype.h>
#include "mm.h"
#if SHMLBA > 16384
#error FIX ME
#endif
static DEFINE_RAW_SPINLOCK(v6_lock);
/*
* Copy the user page. No aliasing to deal with so we can just
* attack the kernel's existing mapping of these pages.
*/
static void v6_copy_user_highpage_nonaliasing(struct page *to,
struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
{
void *kto, *kfrom;
kfrom = kmap_atomic(from);
kto = kmap_atomic(to);
copy_page(kto, kfrom);
kunmap_atomic(kto);
kunmap_atomic(kfrom);
}
/*
* Clear the user page. No aliasing to deal with so we can just
* attack the kernel's existing mapping of this page.
*/
static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned long vaddr)
{
void *kaddr = kmap_atomic(page);
clear_page(kaddr);
kunmap_atomic(kaddr);
}
/*
* Discard data in the kernel mapping for the new page.
* FIXME: needs this MCRR to be supported.
*/
static void discard_old_kernel_data(void *kto)
{
__asm__("mcrr p15, 0, %1, %0, c6 @ 0xec401f06"
:
: "r" (kto),
"r" ((unsigned long)kto + PAGE_SIZE - 1)
: "cc");
}
/*
* Copy the page, taking account of the cache colour.
*/
static void v6_copy_user_highpage_aliasing(struct page *to,
struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
{
unsigned int offset = CACHE_COLOUR(vaddr);
unsigned long kfrom, kto;
if (!test_and_set_bit(PG_dcache_clean, &from->flags))
mm: fix races between swapoff and flush dcache Thanks to commit 4b3ef9daa4fc ("mm/swap: split swap cache into 64MB trunks"), after swapoff the address_space associated with the swap device will be freed. So page_mapping() users which may touch the address_space need some kind of mechanism to prevent the address_space from being freed during accessing. The dcache flushing functions (flush_dcache_page(), etc) in architecture specific code may access the address_space of swap device for anonymous pages in swap cache via page_mapping() function. But in some cases there are no mechanisms to prevent the swap device from being swapoff, for example, CPU1 CPU2 __get_user_pages() swapoff() flush_dcache_page() mapping = page_mapping() ... exit_swap_address_space() ... kvfree(spaces) mapping_mapped(mapping) The address space may be accessed after being freed. But from cachetlb.txt and Russell King, flush_dcache_page() only care about file cache pages, for anonymous pages, flush_anon_page() should be used. The implementation of flush_dcache_page() in all architectures follows this too. They will check whether page_mapping() is NULL and whether mapping_mapped() is true to determine whether to flush the dcache immediately. And they will use interval tree (mapping->i_mmap) to find all user space mappings. While mapping_mapped() and mapping->i_mmap isn't used by anonymous pages in swap cache at all. So, to fix the race between swapoff and flush dcache, __page_mapping() is add to return the address_space for file cache pages and NULL otherwise. All page_mapping() invoking in flush dcache functions are replaced with page_mapping_file(). [akpm@linux-foundation.org: simplify page_mapping_file(), per Mike] Link: http://lkml.kernel.org/r/20180305083634.15174-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Zankel <chris@zankel.net> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Ley Foon Tan <lftan@altera.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05 23:24:39 +00:00
__flush_dcache_page(page_mapping_file(from), from);
/* FIXME: not highmem safe */
discard_old_kernel_data(page_address(to));
/*
* Now copy the page using the same cache colour as the
* pages ultimate destination.
*/
raw_spin_lock(&v6_lock);
kfrom = COPYPAGE_V6_FROM + (offset << PAGE_SHIFT);
kto = COPYPAGE_V6_TO + (offset << PAGE_SHIFT);
set_top_pte(kfrom, mk_pte(from, PAGE_KERNEL));
set_top_pte(kto, mk_pte(to, PAGE_KERNEL));
copy_page((void *)kto, (void *)kfrom);
raw_spin_unlock(&v6_lock);
}
/*
* Clear the user page. We need to deal with the aliasing issues,
* so remap the kernel page into the same cache colour as the user
* page.
*/
static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
{
unsigned long to = COPYPAGE_V6_TO + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
/* FIXME: not highmem safe */
discard_old_kernel_data(page_address(page));
/*
* Now clear the page using the same cache colour as
* the pages ultimate destination.
*/
raw_spin_lock(&v6_lock);
set_top_pte(to, mk_pte(page, PAGE_KERNEL));
clear_page((void *)to);
raw_spin_unlock(&v6_lock);
}
struct cpu_user_fns v6_user_fns __initdata = {
.cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
.cpu_copy_user_highpage = v6_copy_user_highpage_nonaliasing,
};
static int __init v6_userpage_init(void)
{
if (cache_is_vipt_aliasing()) {
cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
}
return 0;
}
core_initcall(v6_userpage_init);