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BACKPORT: arm64: mm: Make hibernation aware of KFENCE

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In the restore path, swsusp_arch_suspend_exit uses copy_page() to
over-write memory. However, with features like KFENCE enabled, there could
be situations where it may have marked some pages as not valid, due to
which it could be reported as invalid accesses.

Consider a situation where page 'P' was part of the hibernation image.
Now, when the resume kernel tries to restore the pages, the same page 'P'
is already in use in the resume kernel and is kfence protected, due to
which its mapping is removed from linear map. Since restoring pages happens
with the resume kernel page tables, we would end up accessing 'P' during
copy and results in kernel pagefault.

The proposed fix tries to solve this issue by marking PTE as valid for such
kfence protected pages.

Co-developed-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Signed-off-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Signed-off-by: Nikhil V <quic_nprakash@quicinc.com>
Link: https://lore.kernel.org/r/20230713070757.4093-1-quic_nprakash@quicinc.com
Signed-off-by: Will Deacon <will@kernel.org>

Bug: 340049585
Change-Id: I476b3bdcd13ebf66ae26c67a1ff61221e01d41e1
(cherry picked from commit a8bd38dbc57c2fe074df2c9e549b9c2ad3183c83)
[Srinivas: Resolved minor conflict to apply changes in arch/arm64/kernel/hibernate.c]
Signed-off-by: Kamati Srinivas <quic_kamasrin@quicinc.com>
This commit is contained in:
Nikhil V 2023-07-13 12:37:57 +05:30 committed by Greg Kroah-Hartman
parent d615d2d800
commit 028de5c48b
1 changed files with 3 additions and 1 deletions
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4
arch/arm64/kernel/hibernate.c
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@ -39,6 +39,7 @@
#include <asm/suspend.h>
#include <asm/sysreg.h>
#include <asm/virt.h>
#include <linux/kfence.h>
/*
* Hibernate core relies on this value being 0 on resume, and marks it
@ -473,7 +474,8 @@ static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
* the temporary mappings we use during restore.
*/
set_pte(dst_ptep, pte_mkwrite(pte));
} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
} else if ((debug_pagealloc_enabled() ||
is_kfence_address((void *)addr)) && !pte_none(pte)) {
/*
* debug_pagealloc will removed the PTE_VALID bit if
* the page isn't in use by the resume kernel. It may have