linux-kernel - [PATCH v16 04/25] arm64: mm: Add p?d

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Message-Id: <20191206135316.47703-5-steven.price@arm.com>
Date:   Fri,  6 Dec 2019 13:52:55 +0000
From:   Steven Price <steven.price@....com>
To:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc:     Steven Price <steven.price@....com>,
        Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        James Morse <james.morse@....com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mark Rutland <Mark.Rutland@....com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>
Subject: [PATCH v16 04/25] arm64: mm: Add p?d_leaf() definitions

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information will be provided by the
p?d_leaf() functions/macros.

For arm64, we already have p?d_sect() macros which we can reuse for
p?d_leaf().

pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3
or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is
configured this way then architecturally it isn't allowed to have a
large page at this level, and any code using these page walking macros
is implicitly relying on the page size/number of levels being the same as
the kernel. So it is safe to reuse this for p?d_leaf() as it is an
architectural restriction.

CC: Catalin Marinas <catalin.marinas@....com>
CC: Will Deacon <will@...nel.org>
Acked-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/include/asm/pgtable.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 5d15b4735a0e..40df7e16d397 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -445,6 +445,7 @@ 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)
 
 #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3
 static inline bool pud_sect(pud_t pud) { return false; }
@@ -529,6 +530,7 @@ static inline void pte_unmap(pte_t *pte) { }
 #define pud_none(pud)		(!pud_val(pud))
 #define pud_bad(pud)		(!(pud_val(pud) & PUD_TABLE_BIT))
 #define pud_present(pud)	pte_present(pud_pte(pud))
+#define pud_leaf(pud)		pud_sect(pud)
 #define pud_valid(pud)		pte_valid(pud_pte(pud))
 
 static inline void set_pud(pud_t *pudp, pud_t pud)
-- 
2.20.1