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arm64/mm: Simplify and document pte_to_phys() for 52 bit addresses

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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 <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Ard Biesheuvel <[email protected]>
Suggested-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>
This commit is contained in:
Anshuman Khandual authored and Will Deacon committed 2022-11-09 18:13:18 +00:00
1 parent f0c4d9fc9c
commit a4ee28615c
3 files changed
+6 -7
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arch/arm64/include/asm/assembler.h
+3 -5
View File
@@ -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
arch/arm64/include/asm/pgtable-hwdef.h
+1
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@@ -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
arch/arm64/include/asm/pgtable.h
+2 -2
View File
@@ -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)