97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
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/*
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* arch/i386/mm/boot_ioremap.c
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*
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* Re-map functions for early boot-time before paging_init() when the
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* boot-time pagetables are still in use
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*
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* Written by Dave Hansen <haveblue@us.ibm.com>
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*/
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/*
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* We need to use the 2-level pagetable functions, but CONFIG_X86_PAE
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* keeps that from happenning. If anyone has a better way, I'm listening.
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*
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* boot_pte_t is defined only if this all works correctly
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*/
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#undef CONFIG_X86_PAE
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <linux/init.h>
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#include <linux/stddef.h>
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/*
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* I'm cheating here. It is known that the two boot PTE pages are
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* allocated next to each other. I'm pretending that they're just
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* one big array.
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*/
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#define BOOT_PTE_PTRS (PTRS_PER_PTE*2)
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#define boot_pte_index(address) \
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(((address) >> PAGE_SHIFT) & (BOOT_PTE_PTRS - 1))
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static inline boot_pte_t* boot_vaddr_to_pte(void *address)
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{
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boot_pte_t* boot_pg = (boot_pte_t*)pg0;
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return &boot_pg[boot_pte_index((unsigned long)address)];
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}
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/*
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* This is only for a caller who is clever enough to page-align
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* phys_addr and virtual_source, and who also has a preference
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* about which virtual address from which to steal ptes
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*/
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static void __boot_ioremap(unsigned long phys_addr, unsigned long nrpages,
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void* virtual_source)
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{
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boot_pte_t* pte;
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int i;
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char *vaddr = virtual_source;
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pte = boot_vaddr_to_pte(virtual_source);
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for (i=0; i < nrpages; i++, phys_addr += PAGE_SIZE, pte++) {
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set_pte(pte, pfn_pte(phys_addr>>PAGE_SHIFT, PAGE_KERNEL));
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__flush_tlb_one(&vaddr[i*PAGE_SIZE]);
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}
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}
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/* the virtual space we're going to remap comes from this array */
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#define BOOT_IOREMAP_PAGES 4
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#define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE)
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static __initdata char boot_ioremap_space[BOOT_IOREMAP_SIZE]
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__attribute__ ((aligned (PAGE_SIZE)));
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/*
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* This only applies to things which need to ioremap before paging_init()
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* bt_ioremap() and plain ioremap() are both useless at this point.
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*
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* When used, we're still using the boot-time pagetables, which only
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* have 2 PTE pages mapping the first 8MB
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*
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* There is no unmap. The boot-time PTE pages aren't used after boot.
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* If you really want the space back, just remap it yourself.
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* boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE)
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*/
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__init void* boot_ioremap(unsigned long phys_addr, unsigned long size)
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{
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unsigned long last_addr, offset;
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unsigned int nrpages;
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last_addr = phys_addr + size - 1;
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/* page align the requested address */
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offset = phys_addr & ~PAGE_MASK;
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phys_addr &= PAGE_MASK;
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size = PAGE_ALIGN(last_addr) - phys_addr;
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nrpages = size >> PAGE_SHIFT;
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if (nrpages > BOOT_IOREMAP_PAGES)
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return NULL;
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__boot_ioremap(phys_addr, nrpages, boot_ioremap_space);
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return &boot_ioremap_space[offset];
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}
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