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https://github.com/drasko/codezero.git
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93 lines
2.6 KiB
C
93 lines
2.6 KiB
C
/*
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* Initialise the memory structures.
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*
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* Copyright (C) 2007 Bahadir Balban
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*/
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#include <kdata.h>
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#include <memory.h>
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#include <l4/macros.h>
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#include <l4/config.h>
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#include <l4/types.h>
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#include <l4/generic/space.h>
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#include <l4lib/arch/syslib.h>
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#include INC_GLUE(memory.h)
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#include INC_SUBARCH(mm.h)
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#include <memory.h>
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struct membank membank[1];
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struct page *page_array;
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void *phys_to_virt(void *addr)
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{
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return addr + INITTASK_OFFSET;
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}
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void *virt_to_phys(void *addr)
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{
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return addr - INITTASK_OFFSET;
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}
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/* Allocates page descriptors and initialises them using page_map information */
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void init_physmem(struct initdata *initdata, struct membank *membank)
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{
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struct page_bitmap *pmap = &initdata->page_map;
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int npages = pmap->pfn_end - pmap->pfn_start;
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/* Allocation marks for the struct page array */
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int pg_npages, pg_spfn, pg_epfn;
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unsigned long ffree_addr;
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/*
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* Means the page array won't map one to one to pfns. That's ok,
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* but we dont allow it for now.
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*/
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BUG_ON(pmap->pfn_start);
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membank[0].start = __pfn_to_addr(pmap->pfn_start);
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membank[0].end = __pfn_to_addr(pmap->pfn_end);
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/* First find the first free page after last used page */
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for (int i = 0; i < npages; i++)
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if ((pmap->map[BITWISE_GETWORD(i)] & BITWISE_GETBIT(i)))
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membank[0].free = (i + 1) * PAGE_SIZE;
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BUG_ON(membank[0].free >= membank[0].end);
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/*
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* One struct page for every physical page. Calculate how many pages
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* needed for page structs, start and end pfn marks.
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*/
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pg_npages = __pfn((sizeof(struct page) * npages));
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/* These are relative pfn offsets to the start of the memory bank */
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pg_spfn = __pfn(membank[0].free) - __pfn(membank[0].start);
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pg_epfn = pg_spfn + pg_npages;
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/* Use free pages from the bank as the space for struct page array */
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membank[0].page_array = l4_map_helper((void *)membank[0].free,
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pg_npages);
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/* Update free memory left */
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membank[0].free += pg_npages * PAGE_SIZE;
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/* Update page bitmap for the pages used for the page array */
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for (int i = pg_spfn; i < pg_epfn; i++)
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pmap->map[BITWISE_GETWORD(i)] |= BITWISE_GETBIT(i);
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/* Initialise the page array */
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for (int i = 0; i < npages; i++) {
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INIT_LIST_HEAD(&membank[0].page_array[i].list);
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/* Set use counts for pages the kernel has already used up */
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if (!(pmap->map[BITWISE_GETWORD(i)] & BITWISE_GETBIT(i)))
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membank[0].page_array[i].count = -1;
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else /* Last page used +1 is free */
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ffree_addr = (i + 1) * PAGE_SIZE;
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}
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/* First free address must come up the same for both */
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BUG_ON(ffree_addr != membank[0].free);
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/* Set global page array to this bank's array */
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page_array = membank[0].page_array;
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}
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