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4d8e74ad45
The final part of [data, end) segment may overflow into the next page of
init_pg_end[1] which is the gap page before early_init_stack[2]:
[1]
crash_arm64_v9.0.1> vtop ffffffed00601000
VIRTUAL PHYSICAL
ffffffed00601000 83401000
PAGE DIRECTORY: ffffffecffd62000
PGD: ffffffecffd62da0 => 10000000833fb003
PMD: ffffff80033fb018 => 10000000833fe003
PTE: ffffff80033fe008 => 68000083401f03
PAGE: 83401000
PTE PHYSICAL FLAGS
68000083401f03 83401000 (VALID|SHARED|AF|NG|PXN|UXN)
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffffec00d0040 83401000 0 0 1 4000 reserved
[2]
ffffffed002c8000 (r) __pi__data
ffffffed0054e000 (d) __pi___bss_start
ffffffed005f5000 (b) __pi_init_pg_dir
ffffffed005fe000 (b) __pi_init_pg_end
ffffffed005ff000 (B) early_init_stack
ffffffed00608000 (b) __pi__end
For 4K pages, the early kernel mapping may use 2MB block entries but the
kernel segments are only 64KB aligned. Segment boundaries that fall
within a 2MB block therefore require a PTE table so that different
attributes can be applied on either side of the boundary.
KERNEL_SEGMENT_COUNT still correctly counts the five permanent kernel
VMAs registered by declare_kernel_vmas(). However, since commit
5973a62efa ("arm64: map [_text, _stext) virtual address range
non-executable+read-only"), the early mapper also maps [_text, _stext)
separately from [_stext, _etext). This adds one more early-only split
and can require one more page-table page than the existing
EARLY_SEGMENT_EXTRA_PAGES allowance reserves.
Increase the 4K-page early mapping allowance by one page to cover that
additional split.
Fixes: 5973a62efa ("arm64: map [_text, _stext) virtual address range non-executable+read-only")
Assisted-by: TRAE:GLM-5.1
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
[catalin.marinas@arm.com: rewrote part of the commit log]
[catalin.marinas@arm.com: expanded the code comment]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
92 lines
3.5 KiB
C
92 lines
3.5 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, kimage_limit, 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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/*
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* KERNEL_SEGMENT_COUNT counts the permanent kernel VMAs. The early mapping
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* has one additional split, [_text, _stext). Reserve one more page for the
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* SWAPPER_BLOCK_SIZE-unaligned boundaries.
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*/
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#define EARLY_SEGMENT_EXTRA_PAGES (KERNEL_SEGMENT_COUNT + 2)
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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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