linux-kernel - [PATCH v2] arm64: mm: fix pmd

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Message-Id: <20220411122653.40284-1-songmuchun@bytedance.com>
Date:   Mon, 11 Apr 2022 20:26:53 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     will@...nel.org, catalin.marinas@....com,
        akpm@...ux-foundation.org, anshuman.khandual@....com,
        steven.price@....com, lengxujun2007@....com, arnd@...db.de,
        smuchun@...il.com, duanxiongchun@...edance.com,
        quic_qiancai@...cinc.com, aneesh.kumar@...ux.ibm.com
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v2] arm64: mm: fix pmd_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.

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>
---
v2:
- Replace pmd_present() with pmd_val() since we expect pmd_leaf() works
  well on non-present pmd case.

 arch/arm64/include/asm/pgtable.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index ad9b221963d4..00cdd2d895d3 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_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
 #define pmd_bad(pmd)		(!pmd_table(pmd))
 
 #define pmd_leaf_size(pmd)	(pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE)
-- 
2.11.0