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Address bytes shifted with a single 64 bit page table entry (any page table level) has been always hard coded as 3 (aka 2^3 = 8). Although intuitive it is not very readable or easy to reason about. Besides it is going to change with D128, where each 128 bit page table entry will shift address bytes by 4 (aka 2^4 = 16) instead. Let's just formalise this address bytes shift value into a new macro called PTDESC_ORDER establishing a logical abstraction, thus improving readability as well. While here re-organize EARLY_LEVEL macro along with its dependents for better clarity. This does not cause any functional change. Also replace all (PAGE_SHIFT - PTDESC_ORDER) instances with PTDESC_TABLE_SHIFT. Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: kasan-dev@googlegroups.com Acked-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Link: https://lore.kernel.org/r/20250311045710.550625-1-anshuman.khandual@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
87 lines
3.3 KiB
C
87 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Kernel page table mapping
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*
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* Copyright (C) 2015 ARM Ltd.
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*/
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#ifndef __ASM_KERNEL_PGTABLE_H
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#define __ASM_KERNEL_PGTABLE_H
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#include <asm/boot.h>
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#include <asm/pgtable-hwdef.h>
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#include <asm/sparsemem.h>
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/*
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* The physical and virtual addresses of the start of the kernel image are
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* equal modulo 2 MiB (per the arm64 booting.txt requirements). Hence we can
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* use section mapping with 4K (section size = 2M) but not with 16K (section
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* size = 32M) or 64K (section size = 512M).
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*/
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#if defined(PMD_SIZE) && PMD_SIZE <= MIN_KIMG_ALIGN
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#define SWAPPER_BLOCK_SHIFT PMD_SHIFT
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#define SWAPPER_SKIP_LEVEL 1
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#else
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#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT
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#define SWAPPER_SKIP_LEVEL 0
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#endif
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#define SWAPPER_BLOCK_SIZE (UL(1) << SWAPPER_BLOCK_SHIFT)
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#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - SWAPPER_SKIP_LEVEL)
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#define INIT_IDMAP_PGTABLE_LEVELS (IDMAP_LEVELS - SWAPPER_SKIP_LEVEL)
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#define IDMAP_VA_BITS 48
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#define IDMAP_LEVELS ARM64_HW_PGTABLE_LEVELS(IDMAP_VA_BITS)
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#define IDMAP_ROOT_LEVEL (4 - IDMAP_LEVELS)
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/*
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* A relocatable kernel may execute from an address that differs from the one at
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* which it was linked. In the worst case, its runtime placement may intersect
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* with two adjacent PGDIR entries, which means that an additional page table
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* may be needed at each subordinate level.
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*/
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#define EXTRA_PAGE __is_defined(CONFIG_RELOCATABLE)
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#define SPAN_NR_ENTRIES(vstart, vend, shift) \
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((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1)
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#define EARLY_ENTRIES(lvl, vstart, vend) \
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SPAN_NR_ENTRIES(vstart, vend, SWAPPER_BLOCK_SHIFT + lvl * PTDESC_TABLE_SHIFT)
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#define EARLY_LEVEL(lvl, lvls, vstart, vend, add) \
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((lvls) > (lvl) ? EARLY_ENTRIES(lvl, vstart, vend) + (add) : 0)
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#define EARLY_PAGES(lvls, vstart, vend, add) (1 /* PGDIR page */ \
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+ EARLY_LEVEL(3, (lvls), (vstart), (vend), add) /* each entry needs a next level page table */ \
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+ EARLY_LEVEL(2, (lvls), (vstart), (vend), add) /* each entry needs a next level page table */ \
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+ EARLY_LEVEL(1, (lvls), (vstart), (vend), add))/* each entry needs a next level page table */
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#define INIT_DIR_SIZE (PAGE_SIZE * (EARLY_PAGES(SWAPPER_PGTABLE_LEVELS, KIMAGE_VADDR, _end, EXTRA_PAGE) \
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+ EARLY_SEGMENT_EXTRA_PAGES))
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#define INIT_IDMAP_DIR_PAGES (EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, KIMAGE_VADDR, _end, 1))
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#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + EARLY_IDMAP_EXTRA_PAGES) * PAGE_SIZE)
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#define INIT_IDMAP_FDT_PAGES (EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, 0UL, UL(MAX_FDT_SIZE), 1) - 1)
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#define INIT_IDMAP_FDT_SIZE ((INIT_IDMAP_FDT_PAGES + EARLY_IDMAP_EXTRA_FDT_PAGES) * PAGE_SIZE)
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/* The number of segments in the kernel image (text, rodata, inittext, initdata, data+bss) */
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#define KERNEL_SEGMENT_COUNT 5
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#if SWAPPER_BLOCK_SIZE > SEGMENT_ALIGN
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#define EARLY_SEGMENT_EXTRA_PAGES (KERNEL_SEGMENT_COUNT + 1)
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/*
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* The initial ID map consists of the kernel image, mapped as two separate
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* segments, and may appear misaligned wrt the swapper block size. This means
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* we need 3 additional pages. The DT could straddle a swapper block boundary,
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* so it may need 2.
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*/
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#define EARLY_IDMAP_EXTRA_PAGES 3
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#define EARLY_IDMAP_EXTRA_FDT_PAGES 2
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#else
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#define EARLY_SEGMENT_EXTRA_PAGES 0
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#define EARLY_IDMAP_EXTRA_PAGES 0
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#define EARLY_IDMAP_EXTRA_FDT_PAGES 0
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#endif
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#endif /* __ASM_KERNEL_PGTABLE_H */
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