linux-kernel - [PATCH v3] arm64: mm: fix p?d

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Message-Id: <20220422060033.48711-1-songmuchun@bytedance.com>
Date:   Fri, 22 Apr 2022 14:00:33 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     will@...nel.org, steven.price@....com, catalin.marinas@....com,
        akpm@...ux-foundation.org, anshuman.khandual@....com,
        lengxujun2007@....com, arnd@...db.de, quic_qiancai@...cinc.com,
        aneesh.kumar@...ux.ibm.com
Cc:     smuchun@...il.com, duanxiongchun@...edance.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v3] arm64: mm: fix p?d_leaf()

The pmd_leaf() is used to test a leaf mapped PMD, however, it misses
the PROT_NONE mapped PMD on arm64.  Fix it.  A real world issue [1]
caused by this was reported by Qian Cai. Also fix pud_leaf().

Link: https://patchwork.kernel.org/comment/24798260/ [1]
Fixes: 8aa82df3c123 ("arm64: mm: add p?d_leaf() definitions")
Reported-by: Qian Cai <quic_qiancai@...cinc.com>
Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
v3:
 - Fix pud_leaf() as well.
 - Rework pmd_leaf() as present && !table.

 arch/arm64/include/asm/pgtable.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 930077f7b572..9aae3773b6c4 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -551,7 +551,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 				 PMD_TYPE_TABLE)
 #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
 				 PMD_TYPE_SECT)
-#define pmd_leaf(pmd)		pmd_sect(pmd)
+#define pmd_leaf(pmd)		(pmd_present(pmd) && !pmd_table(pmd))
 #define pmd_bad(pmd)		(!pmd_table(pmd))
 
 #define pmd_leaf_size(pmd)	(pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE)
@@ -641,7 +641,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 #define pud_none(pud)		(!pud_val(pud))
 #define pud_bad(pud)		(!pud_table(pud))
 #define pud_present(pud)	pte_present(pud_pte(pud))
-#define pud_leaf(pud)		pud_sect(pud)
+#define pud_leaf(pud)		(pud_present(pud) && !pud_table(pud))
 #define pud_valid(pud)		pte_valid(pud_pte(pud))
 
 static inline void set_pud(pud_t *pudp, pud_t pud)
-- 
2.11.0