From a4ee28615c7a1e2925e1fcb4ba0fa1aeee633d78 Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Mon, 7 Nov 2022 19:47:53 +0530 Subject: [PATCH] arm64/mm: Simplify and document pte_to_phys() for 52 bit addresses pte_to_phys() assembly definition does multiple bits field transformations to derive physical address, embedded inside a page table entry. Unlike its C counter part i.e __pte_to_phys(), pte_to_phys() is not very apparent. It simplifies these operations via a new macro PTE_ADDR_HIGH_SHIFT indicating how far the pte encoded higher address bits need to be left shifted. While here, this also updates __pte_to_phys() and __phys_to_pte_val(). Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Brown Cc: Mark Rutland Cc: Ard Biesheuvel Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Ard Biesheuvel Suggested-by: Ard Biesheuvel Signed-off-by: Anshuman Khandual Link: https://lore.kernel.org/r/20221107141753.2938621-1-anshuman.khandual@arm.com Signed-off-by: Will Deacon --- arch/arm64/include/asm/assembler.h | 8 +++----- arch/arm64/include/asm/pgtable-hwdef.h | 1 + arch/arm64/include/asm/pgtable.h | 4 ++-- 3 files changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index e5957a53be398..89038067ef342 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -660,12 +660,10 @@ alternative_endif .endm .macro pte_to_phys, phys, pte -#ifdef CONFIG_ARM64_PA_BITS_52 - ubfiz \phys, \pte, #(48 - 16 - 12), #16 - bfxil \phys, \pte, #16, #32 - lsl \phys, \phys, #16 -#else and \phys, \pte, #PTE_ADDR_MASK +#ifdef CONFIG_ARM64_PA_BITS_52 + orr \phys, \phys, \phys, lsl #PTE_ADDR_HIGH_SHIFT + and \phys, \phys, GENMASK_ULL(PHYS_MASK_SHIFT - 1, PAGE_SHIFT) #endif .endm diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index 5ab8d163198fd..f658aafc47dfa 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -159,6 +159,7 @@ #ifdef CONFIG_ARM64_PA_BITS_52 #define PTE_ADDR_HIGH (_AT(pteval_t, 0xf) << 12) #define PTE_ADDR_MASK (PTE_ADDR_LOW | PTE_ADDR_HIGH) +#define PTE_ADDR_HIGH_SHIFT 36 #else #define PTE_ADDR_MASK PTE_ADDR_LOW #endif diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 71a1af42f0e89..daedd6172227f 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -77,11 +77,11 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; static inline phys_addr_t __pte_to_phys(pte_t pte) { return (pte_val(pte) & PTE_ADDR_LOW) | - ((pte_val(pte) & PTE_ADDR_HIGH) << 36); + ((pte_val(pte) & PTE_ADDR_HIGH) << PTE_ADDR_HIGH_SHIFT); } static inline pteval_t __phys_to_pte_val(phys_addr_t phys) { - return (phys | (phys >> 36)) & PTE_ADDR_MASK; + return (phys | (phys >> PTE_ADDR_HIGH_SHIFT)) & PTE_ADDR_MASK; } #else #define __pte_to_phys(pte) (pte_val(pte) & PTE_ADDR_MASK) -- 2.30.2