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8b81576c16
Add HIGHMEM (High Memory) support for LoongArch, mostly needed by 32BIT kernel because the size of kernel virtual memory space is only 512MB and the size of usable physical memory is only 256MB in this case. HIGHMEM adds permanent kernel mapping (PKMAP) and fixed kernel mapping (FIX_KMAP), which increase usable physical memory up to 2.25GB (2304MB). We can just use the generic copy_user_highpage(), so remove the custom version. Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* highmem.h: virtual kernel memory mappings for high memory
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*
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* Used in CONFIG_HIGHMEM systems for memory pages which
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* are not addressable by direct kernel virtual addresses.
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*
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* Copyright (C) 2025 Loongson Technology Corporation Limited
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*/
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#ifndef _ASM_HIGHMEM_H
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#define _ASM_HIGHMEM_H
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#ifdef __KERNEL__
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#include <asm/kmap_size.h>
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#ifndef __ASSEMBLER__
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extern pte_t *pkmap_page_table;
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#define ARCH_HAS_KMAP_FLUSH_TLB
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void kmap_flush_tlb(unsigned long addr);
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#endif /* !__ASSEMBLER__ */
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/*
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* Right now we initialize only a single pte table. It can be extended
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* easily, subsequent pte tables have to be allocated in one physical
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* chunk of RAM.
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*/
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#define LAST_PKMAP 1024
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#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
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#define PKMAP_NR(virt) ((virt - PKMAP_BASE) >> PAGE_SHIFT)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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#define flush_cache_kmaps() do {} while (0)
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#define arch_kmap_local_post_map(vaddr, pteval) local_flush_tlb_one(vaddr)
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#define arch_kmap_local_post_unmap(vaddr) local_flush_tlb_one(vaddr)
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#endif /* __KERNEL__ */
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#endif /* _ASM_HIGHMEM_H */
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