2dde02ab6d
ARCv2 MMU is software walked and Linux implements 2 levels of paging: pgd/pte.
Forthcoming hw will have multiple levels, so this change preps mm code
for same. It is also fun to try multi levels even on soft-walked code to
ensure generic mm code is robust to handle.
overview
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2 levels {pgd, pte} : pmd is folded but pmd_* macros are valid and operate on pgd
3 levels {pgd, pmd, pte}:
- pud is folded and pud_* macros point to pgd
- pmd_* macros operate on actual pmd
code changes
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1. #include <asm-generic/pgtable-nopud.h>
2. Define CONFIG_PGTABLE_LEVELS 3
3a. Define PMD_SHIFT, PMD_SIZE, PMD_MASK, pmd_t
3b. Define pmd_val() which actually deals with pmd
(pmd_offset(), pmd_index() are provided by generic code)
3c. pmd_alloc_one()/pmd_free() also provided by generic code
(pmd_populate/pmd_free already exist)
4. Define pud_none(), pud_bad() macros based on generic pud_val() which
internally pertains to pgd now.
4b. define pud_populate() to just setup pgd
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
154 lines
4.5 KiB
C
154 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2020 Synopsys, Inc. (www.synopsys.com)
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*/
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/*
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* Helpers for implemenintg paging levels
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*/
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#ifndef _ASM_ARC_PGTABLE_LEVELS_H
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#define _ASM_ARC_PGTABLE_LEVELS_H
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#if CONFIG_PGTABLE_LEVELS == 2
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/*
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* 2 level paging setup for software walked MMUv3 (ARC700) and MMUv4 (HS)
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*
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* [31] 32 bit virtual address [0]
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* -------------------------------------------------------
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* | | <---------- PGDIR_SHIFT ----------> |
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* | | | <-- PAGE_SHIFT --> |
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* -------------------------------------------------------
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* | | |
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* | | --> off in page frame
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* | ---> index into Page Table
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* ----> index into Page Directory
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*
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* Given software walk, the vaddr split is arbitrary set to 11:8:13
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* However enabling of super page in a 2 level regime pegs PGDIR_SHIFT to
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* super page size.
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*/
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#if defined(CONFIG_ARC_HUGEPAGE_16M)
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#define PGDIR_SHIFT 24
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#elif defined(CONFIG_ARC_HUGEPAGE_2M)
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#define PGDIR_SHIFT 21
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#else
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/*
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* No Super page case
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* Default value provides 11:8:13 (8K), 10:10:12 (4K)
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* Limits imposed by pgtable_t only PAGE_SIZE long
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* (so 4K page can only have 1K entries: or 10 bits)
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*/
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#ifdef CONFIG_ARC_PAGE_SIZE_4K
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#define PGDIR_SHIFT 22
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#else
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#define PGDIR_SHIFT 21
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#endif
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#endif
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#else /* CONFIG_PGTABLE_LEVELS != 2 */
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/*
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* A default 3 level paging testing setup in software walked MMU
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* MMUv4 (8K page): <4> : <7> : <8> : <13>
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*/
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#define PGDIR_SHIFT 28
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#if CONFIG_PGTABLE_LEVELS > 2
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#define PMD_SHIFT 21
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#endif
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#endif /* CONFIG_PGTABLE_LEVELS */
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#define PGDIR_SIZE BIT(PGDIR_SHIFT)
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#define PGDIR_MASK (~(PGDIR_SIZE - 1))
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#define PTRS_PER_PGD BIT(32 - PGDIR_SHIFT)
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#if CONFIG_PGTABLE_LEVELS > 2
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#define PMD_SIZE BIT(PMD_SHIFT)
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#define PMD_MASK (~(PMD_SIZE - 1))
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#define PTRS_PER_PMD BIT(PGDIR_SHIFT - PMD_SHIFT)
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#endif
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#define PTRS_PER_PTE BIT(PMD_SHIFT - PAGE_SHIFT)
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#ifndef __ASSEMBLY__
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#if CONFIG_PGTABLE_LEVELS > 2
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#include <asm-generic/pgtable-nopud.h>
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#else
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#include <asm-generic/pgtable-nopmd.h>
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#endif
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/*
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* 1st level paging: pgd
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*/
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#define pgd_index(addr) ((addr) >> PGDIR_SHIFT)
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#define pgd_offset(mm, addr) (((mm)->pgd) + pgd_index(addr))
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#define pgd_offset_k(addr) pgd_offset(&init_mm, addr)
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#define pgd_ERROR(e) \
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pr_crit("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
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#if CONFIG_PGTABLE_LEVELS > 2
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/* In 3 level paging, pud_* macros work on pgd */
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#define pud_none(x) (!pud_val(x))
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#define pud_bad(x) ((pud_val(x) & ~PAGE_MASK))
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#define pud_present(x) (pud_val(x))
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#define pud_clear(xp) do { pud_val(*(xp)) = 0; } while (0)
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#define pud_pgtable(pud) ((pmd_t *)(pud_val(pud) & PAGE_MASK))
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#define pud_page(pud) virt_to_page(pud_pgtable(pud))
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#define set_pud(pudp, pud) (*(pudp) = pud)
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/*
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* 2nd level paging: pmd
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*/
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#define pmd_ERROR(e) \
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pr_crit("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))
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#define pmd_pfn(pmd) ((pmd_val(pmd) & PMD_MASK) >> PAGE_SHIFT)
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#define pfn_pmd(pfn,prot) __pmd(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
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#define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot)
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#endif
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/*
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* Due to the strange way generic pgtable level folding works, the pmd_* macros
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* - are valid even for 2 levels (which supposedly only has pgd - pte)
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* - behave differently for 2 vs. 3
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* In 2 level paging (pgd -> pte), pmd_* macros work on pgd
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* In 3+ level paging (pgd -> pmd -> pte), pmd_* macros work on pmd
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*/
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#define pmd_none(x) (!pmd_val(x))
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#define pmd_bad(x) ((pmd_val(x) & ~PAGE_MASK))
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#define pmd_present(x) (pmd_val(x))
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#define pmd_clear(xp) do { pmd_val(*(xp)) = 0; } while (0)
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#define pmd_page_vaddr(pmd) (pmd_val(pmd) & PAGE_MASK)
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#define pmd_page(pmd) virt_to_page(pmd_page_vaddr(pmd))
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#define set_pmd(pmdp, pmd) (*(pmdp) = pmd)
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#define pmd_pgtable(pmd) ((pgtable_t) pmd_page_vaddr(pmd))
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/*
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* 3rd level paging: pte
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*/
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#define pte_ERROR(e) \
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pr_crit("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
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#define pte_none(x) (!pte_val(x))
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#define pte_present(x) (pte_val(x) & _PAGE_PRESENT)
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#define pte_clear(mm,addr,ptep) set_pte_at(mm, addr, ptep, __pte(0))
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#define pte_page(pte) pfn_to_page(pte_pfn(pte))
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#define set_pte(ptep, pte) ((*(ptep)) = (pte))
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#define pte_pfn(pte) (pte_val(pte) >> PAGE_SHIFT)
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#define pfn_pte(pfn, prot) __pte(__pfn_to_phys(pfn) | pgprot_val(prot))
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#define mk_pte(page, prot) pfn_pte(page_to_pfn(page), prot)
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#ifdef CONFIG_ISA_ARCV2
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#define pmd_leaf(x) (pmd_val(x) & _PAGE_HW_SZ)
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#endif
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#endif /* !__ASSEMBLY__ */
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#endif
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