linux_dsm_epyc7002/arch/unicore32/mm/flush.c

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/*
* linux/arch/unicore32/mm/flush.c
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Copyright (C) 2001-2010 GUAN Xue-tao
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
void flush_cache_mm(struct mm_struct *mm)
{
}
void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end)
{
if (vma->vm_flags & VM_EXEC)
__flush_icache_all();
}
void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr,
unsigned long pfn)
{
}
static void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
unsigned long uaddr, void *kaddr, unsigned long len)
{
/* VIPT non-aliasing D-cache */
if (vma->vm_flags & VM_EXEC) {
unsigned long addr = (unsigned long)kaddr;
__cpuc_coherent_kern_range(addr, addr + len);
}
}
/*
* Copy user data from/to a page which is mapped into a different
* processes address space. Really, we want to allow our "user
* space" model to handle this.
*
* Note that this code needs to run on the current CPU.
*/
void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
unsigned long uaddr, void *dst, const void *src,
unsigned long len)
{
memcpy(dst, src, len);
flush_ptrace_access(vma, page, uaddr, dst, len);
}
void __flush_dcache_page(struct address_space *mapping, struct page *page)
{
/*
* Writeback any data associated with the kernel mapping of this
* page. This ensures that data in the physical page is mutually
* coherent with the kernels mapping.
*/
__cpuc_flush_kern_dcache_area(page_address(page), PAGE_SIZE);
}
/*
* Ensure cache coherency between kernel mapping and userspace mapping
* of this page.
*/
void flush_dcache_page(struct page *page)
{
struct address_space *mapping;
/*
* The zero page is never written to, so never has any dirty
* cache lines, and therefore never needs to be flushed.
*/
if (page == ZERO_PAGE(0))
return;
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>
2018-04-06 06:24:39 +07:00
mapping = page_mapping_file(page);
if (mapping && !mapping_mapped(mapping))
clear_bit(PG_dcache_clean, &page->flags);
else {
__flush_dcache_page(mapping, page);
if (mapping)
__flush_icache_all();
set_bit(PG_dcache_clean, &page->flags);
}
}
EXPORT_SYMBOL(flush_dcache_page);