linux-kernel - [PATCH] arm64/mm: Compute PTRS_PER_[PMD|PUD] independently of PTRS_PER

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Date:   Fri,  8 Apr 2022 09:40:09 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] arm64/mm: Compute PTRS_PER_[PMD|PUD] independently of PTRS_PER_PTE

Possible page table entries (or pointers) on non-zero page table levels are
dependent on a single page size i.e PAGE_SIZE and size required for each
individual page table entry i.e 8 bytes. PTRS_PER_[PMD|PUD] as such are not
related to PTRS_PER_PTE in any manner, as being implied currently. So lets
just make this very explicit and compute these macros independently.

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
This applies on v5.18-rc1

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

diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 66671ff05183..dd3d12bce07b 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -49,7 +49,7 @@
 #define PMD_SHIFT		ARM64_HW_PGTABLE_LEVEL_SHIFT(2)
 #define PMD_SIZE		(_AC(1, UL) << PMD_SHIFT)
 #define PMD_MASK		(~(PMD_SIZE-1))
-#define PTRS_PER_PMD		PTRS_PER_PTE
+#define PTRS_PER_PMD		(1 << (PAGE_SHIFT - 3))
 #endif
 
 /*
@@ -59,7 +59,7 @@
 #define PUD_SHIFT		ARM64_HW_PGTABLE_LEVEL_SHIFT(1)
 #define PUD_SIZE		(_AC(1, UL) << PUD_SHIFT)
 #define PUD_MASK		(~(PUD_SIZE-1))
-#define PTRS_PER_PUD		PTRS_PER_PTE
+#define PTRS_PER_PUD		(1 << (PAGE_SHIFT - 3))
 #endif
 
 /*
-- 
2.20.1