acrn-kernel/arch/arm64/mm/copypage.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Based on arch/arm/mm/copypage.c
*
* Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/bitops.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
#include <asm/mte.h>
void copy_highpage(struct page *to, struct page *from)
{
void *kto = page_address(to);
void *kfrom = page_address(from);
copy_page(kto, kfrom);
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if (kasan_hw_tags_enabled())
page_kasan_tag_reset(to);
arm64: mte: Fix/clarify the PG_mte_tagged semantics commit e059853d14ca4ed0f6a190d7109487918a22a976 upstream. Currently the PG_mte_tagged page flag mostly means the page contains valid tags and it should be set after the tags have been cleared or restored. However, in mte_sync_tags() it is set before setting the tags to avoid, in theory, a race with concurrent mprotect(PROT_MTE) for shared pages. However, a concurrent mprotect(PROT_MTE) with a copy on write in another thread can cause the new page to have stale tags. Similarly, tag reading via ptrace() can read stale tags if the PG_mte_tagged flag is set before actually clearing/restoring the tags. Fix the PG_mte_tagged semantics so that it is only set after the tags have been cleared or restored. This is safe for swap restoring into a MAP_SHARED or CoW page since the core code takes the page lock. Add two functions to test and set the PG_mte_tagged flag with acquire and release semantics. The downside is that concurrent mprotect(PROT_MTE) on a MAP_SHARED page may cause tag loss. This is already the case for KVM guests if a VMM changes the page protection while the guest triggers a user_mem_abort(). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> [pcc@google.com: fix build with CONFIG_ARM64_MTE disabled] Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: Steven Price <steven.price@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Peter Collingbourne <pcc@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221104011041.290951-3-pcc@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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if (system_supports_mte() && page_mte_tagged(from)) {
mte_copy_page_tags(kto, kfrom);
arm64: mte: Fix/clarify the PG_mte_tagged semantics commit e059853d14ca4ed0f6a190d7109487918a22a976 upstream. Currently the PG_mte_tagged page flag mostly means the page contains valid tags and it should be set after the tags have been cleared or restored. However, in mte_sync_tags() it is set before setting the tags to avoid, in theory, a race with concurrent mprotect(PROT_MTE) for shared pages. However, a concurrent mprotect(PROT_MTE) with a copy on write in another thread can cause the new page to have stale tags. Similarly, tag reading via ptrace() can read stale tags if the PG_mte_tagged flag is set before actually clearing/restoring the tags. Fix the PG_mte_tagged semantics so that it is only set after the tags have been cleared or restored. This is safe for swap restoring into a MAP_SHARED or CoW page since the core code takes the page lock. Add two functions to test and set the PG_mte_tagged flag with acquire and release semantics. The downside is that concurrent mprotect(PROT_MTE) on a MAP_SHARED page may cause tag loss. This is already the case for KVM guests if a VMM changes the page protection while the guest triggers a user_mem_abort(). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> [pcc@google.com: fix build with CONFIG_ARM64_MTE disabled] Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: Steven Price <steven.price@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Peter Collingbourne <pcc@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221104011041.290951-3-pcc@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-04 09:10:35 +08:00
set_page_mte_tagged(to);
}
}
EXPORT_SYMBOL(copy_highpage);
void copy_user_highpage(struct page *to, struct page *from,
unsigned long vaddr, struct vm_area_struct *vma)
{
copy_highpage(to, from);
flush_dcache_page(to);
}
EXPORT_SYMBOL_GPL(copy_user_highpage);