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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>
68 lines
1.3 KiB
C
68 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* PGD allocation/freeing
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*
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* Copyright (C) 2012 ARM Ltd.
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* Author: Catalin Marinas <catalin.marinas@arm.com>
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*/
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#include <linux/mm.h>
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#include <linux/gfp.h>
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#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <asm/pgalloc.h>
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#include <asm/page.h>
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#include <asm/tlbflush.h>
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static struct kmem_cache *pgd_cache __ro_after_init;
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static bool pgdir_is_page_size(void)
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{
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if (PGD_SIZE == PAGE_SIZE)
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return true;
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if (CONFIG_PGTABLE_LEVELS == 4)
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return !pgtable_l4_enabled();
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if (CONFIG_PGTABLE_LEVELS == 5)
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return !pgtable_l5_enabled();
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return false;
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}
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pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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gfp_t gfp = GFP_PGTABLE_USER;
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if (pgdir_is_page_size())
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return __pgd_alloc(mm, 0);
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else
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return kmem_cache_alloc(pgd_cache, gfp);
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}
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void pgd_free(struct mm_struct *mm, pgd_t *pgd)
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{
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if (pgdir_is_page_size())
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__pgd_free(mm, pgd);
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else
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kmem_cache_free(pgd_cache, pgd);
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}
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void __init pgtable_cache_init(void)
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{
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if (pgdir_is_page_size())
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return;
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#ifdef CONFIG_ARM64_PA_BITS_52
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/*
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* With 52-bit physical addresses, the architecture requires the
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* top-level table to be aligned to at least 64 bytes.
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*/
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BUILD_BUG_ON(PGD_SIZE < 64);
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#endif
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/*
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* Naturally aligned pgds required by the architecture.
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*/
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pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
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SLAB_PANIC, NULL);
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}
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