linux-kernel - [PATCH] MIPS: fix pmd

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Date:   Wed,  6 Jul 2022 17:07:36 +0800
From:   Hongchen Zhang <zhanghongchen@...ngson.cn>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hongchen Zhang <zhanghongchen@...ngson.cn>
Subject: [PATCH] MIPS: fix pmd_mkinvalid

When a pmd entry is invalidated by pmd_mkinvalid,pmd_present should
return true.
So introduce a _PAGE_PRESENT_INVALID_SHIFT bit to check if a pmd is
present but invalidated by pmd_mkinvalid.

Signed-off-by: Hongchen Zhang <zhanghongchen@...ngson.cn>
---
 arch/mips/include/asm/pgtable-64.h   | 2 +-
 arch/mips/include/asm/pgtable-bits.h | 5 +++++
 arch/mips/include/asm/pgtable.h      | 3 ++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
index 41921ac..1c5ef41 100644
--- a/arch/mips/include/asm/pgtable-64.h
+++ b/arch/mips/include/asm/pgtable-64.h
@@ -265,7 +265,7 @@ static inline int pmd_present(pmd_t pmd)
 {
 #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
 	if (unlikely(pmd_val(pmd) & _PAGE_HUGE))
-		return pmd_val(pmd) & _PAGE_PRESENT;
+		return pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PRESENT_INVALID);
 #endif
 
 	return pmd_val(pmd) != (unsigned long) invalid_pte_table;
diff --git a/arch/mips/include/asm/pgtable-bits.h b/arch/mips/include/asm/pgtable-bits.h
index 2362842..3c176a1e 100644
--- a/arch/mips/include/asm/pgtable-bits.h
+++ b/arch/mips/include/asm/pgtable-bits.h
@@ -49,6 +49,7 @@ enum pgtable_bits {
 
 	/* Used only by software (masked out before writing EntryLo*) */
 	_PAGE_PRESENT_SHIFT = 24,
+	_PAGE_PRESENT_INVALID_SHIFT,
 	_PAGE_WRITE_SHIFT,
 	_PAGE_ACCESSED_SHIFT,
 	_PAGE_MODIFIED_SHIFT,
@@ -80,6 +81,7 @@ enum pgtable_bits {
 
 	/* Used only by software (masked out before writing EntryLo*) */
 	_PAGE_PRESENT_SHIFT = _CACHE_SHIFT + 3,
+	_PAGE_PRESENT_INVALID_SHIFT,
 	_PAGE_NO_READ_SHIFT,
 	_PAGE_WRITE_SHIFT,
 	_PAGE_ACCESSED_SHIFT,
@@ -98,6 +100,7 @@ enum pgtable_bits {
 enum pgtable_bits {
 	/* Used only by software (writes to EntryLo ignored) */
 	_PAGE_PRESENT_SHIFT,
+	_PAGE_PRESENT_INVALID_SHIFT,
 	_PAGE_NO_READ_SHIFT,
 	_PAGE_WRITE_SHIFT,
 	_PAGE_ACCESSED_SHIFT,
@@ -122,6 +125,7 @@ enum pgtable_bits {
 enum pgtable_bits {
 	/* Used only by software (masked out before writing EntryLo*) */
 	_PAGE_PRESENT_SHIFT,
+	_PAGE_PRESENT_INVALID_SHIFT,
 #if !defined(CONFIG_CPU_HAS_RIXI)
 	_PAGE_NO_READ_SHIFT,
 #endif
@@ -152,6 +156,7 @@ enum pgtable_bits {
 
 /* Used only by software */
 #define _PAGE_PRESENT		(1 << _PAGE_PRESENT_SHIFT)
+#define _PAGE_PRESENT_INVALID	(1 << _PAGE_PRESENT_INVALID_SHIFT)
 #define _PAGE_WRITE		(1 << _PAGE_WRITE_SHIFT)
 #define _PAGE_ACCESSED		(1 << _PAGE_ACCESSED_SHIFT)
 #define _PAGE_MODIFIED		(1 << _PAGE_MODIFIED_SHIFT)
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 374c632..cc80211 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -698,7 +698,8 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 
 static inline pmd_t pmd_mkinvalid(pmd_t pmd)
 {
-	pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY);
+	pmd_val(pmd) |= _PAGE_PRESENT_INVALID;
+	pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID);
 
 	return pmd;
 }
-- 
1.8.3.1