linux-kernel - [PATCH] ARM: update __swp_entry_to_pte() to use PTE_TYPE

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Date:   Thu, 13 May 2021 12:27:43 +0100
From:   Russell King <rmk+kernel@...linux.org.uk>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Allison Randal <allison@...utok.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] ARM: update __swp_entry_to_pte() to use PTE_TYPE_FAULT

Swap entries use a faulting PTE which have the least two significant
bits as zero. Due to this, the use of PTE_TYPE_FAULT was overlooked,
but really should have been included in __swp_entry_to_pte().

Convert this macro to use PTE_TYPE_FAULT to properly document what is
going on here, and use __pte() to convert the swp_entry_t to a pte_t.

This results in no change to the resulting kernel text.

Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
---
 arch/arm/include/asm/pgtable.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index c02f24400369..c43e07d6046d 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -303,7 +303,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << __SWP_TYPE_SHIFT) | ((offset) << __SWP_OFFSET_SHIFT) })
 
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
-#define __swp_entry_to_pte(swp)	((pte_t) { (swp).val })
+#define __swp_entry_to_pte(swp)	__pte((swp).val | PTE_TYPE_FAULT)
 
 /*
  * It is an error for the kernel to have more swap files than we can
-- 
2.20.1