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a9b3c355c2
We already have a generic implementation of alloc/free up to P4D level, as
well as pgd_free(). Let's finish the work and add a generic PGD-level
alloc helper as well.
Unlike at lower levels, almost all architectures need some specific magic
at PGD level (typically initialising PGD entries), so introducing a
generic pgd_alloc() isn't worth it. Instead we introduce two new helpers,
__pgd_alloc() and __pgd_free(), and make use of them in the arch-specific
pgd_alloc() and pgd_free() wherever possible. To accommodate as many arch
as possible, __pgd_alloc() takes a page allocation order.
Because pagetable_alloc() allocates zeroed pages, explicit zeroing in
pgd_alloc() becomes redundant and we can get rid of it. Some trivial
implementations of pgd_free() also become unnecessary once __pgd_alloc()
is used; remove them.
Another small improvement is consistent accounting of PGD pages by using
GFP_PGTABLE_{USER,KERNEL} as appropriate.
Not all PGD allocations can be handled by the generic helpers. In
particular, multiple architectures allocate PGDs from a kmem_cache, and
those PGDs may not be page-sized.
Link: https://lkml.kernel.org/r/20250103184415.2744423-6-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Page table support for the Hexagon architecture
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*
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* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
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*/
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#ifndef _ASM_PGALLOC_H
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#define _ASM_PGALLOC_H
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#include <asm/mem-layout.h>
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#include <asm/atomic.h>
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#include <asm-generic/pgalloc.h>
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extern unsigned long long kmap_generation;
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/*
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* Page table creation interface
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*/
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static inline pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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pgd_t *pgd;
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pgd = __pgd_alloc(mm, 0);
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/*
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* There may be better ways to do this, but to ensure
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* that new address spaces always contain the kernel
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* base mapping, and to ensure that the user area is
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* initially marked invalid, initialize the new map
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* map with a copy of the kernel's persistent map.
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*/
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memcpy(pgd, swapper_pg_dir, PTRS_PER_PGD*sizeof(pgd_t));
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mm->context.generation = kmap_generation;
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/* Physical version is what is passed to virtual machine on switch */
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mm->context.ptbase = __pa(pgd);
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return pgd;
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}
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static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
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pgtable_t pte)
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{
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/*
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* Conveniently, zero in 3 LSB means indirect 4K page table.
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* Not so convenient when you're trying to vary the page size.
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*/
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set_pmd(pmd, __pmd(((unsigned long)page_to_pfn(pte) << PAGE_SHIFT) |
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HEXAGON_L1_PTE_SIZE));
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}
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/*
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* Other architectures seem to have ways of making all processes
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* share the same pmd's for their kernel mappings, but the v0.3
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* Hexagon VM spec has a "monolithic" L1 table for user and kernel
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* segments. We track "generations" of the kernel map to minimize
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* overhead, and update the "slave" copies of the kernel mappings
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* as part of switch_mm. However, we still need to update the
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* kernel map of the active thread who's calling pmd_populate_kernel...
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*/
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static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
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pte_t *pte)
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{
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extern spinlock_t kmap_gen_lock;
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pmd_t *ppmd;
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int pmdindex;
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spin_lock(&kmap_gen_lock);
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kmap_generation++;
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mm->context.generation = kmap_generation;
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current->active_mm->context.generation = kmap_generation;
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spin_unlock(&kmap_gen_lock);
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set_pmd(pmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
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/*
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* Now the "slave" copy of the current thread.
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* This is pointer arithmetic, not byte addresses!
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*/
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pmdindex = (pgd_t *)pmd - mm->pgd;
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ppmd = (pmd_t *)current->active_mm->pgd + pmdindex;
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set_pmd(ppmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
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if (pmdindex > max_kernel_seg)
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max_kernel_seg = pmdindex;
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}
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#define __pte_free_tlb(tlb, pte, addr) \
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do { \
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pagetable_dtor((page_ptdesc(pte))); \
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tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \
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} while (0)
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#endif
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