118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
#include "paging.h"
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#include "context.h"
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#include "io.h"
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u32 g_FramePointer;
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u64 *g_PML4;
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void _zero_paging_structure(u64 *Structure)
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{
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for (unsigned i = 0; i < 512; i++)
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Structure[i] = 0;
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}
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u32 _allocate_frame_4k(void)
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{
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u32 Frame = g_FramePointer;
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if (Frame > 0xEFFFFF)
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{
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puts("BUG: Out of extended memory.\n");
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for (;;) {}
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}
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g_FramePointer += 0x1000;
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return Frame;
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}
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void paging_setup(u32 AllocateFramesFrom)
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{
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g_FramePointer = AllocateFramesFrom;
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// set up PML4
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g_PML4 = (u64*)_allocate_frame_4k();
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_zero_paging_structure(g_PML4);
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}
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void paging_map_page(u64 Virtual, u64 Physical)
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{
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if (Virtual % 0x1000 || Physical % 0x1000)
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{
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puts("BUG: Requsted allocation of unaligned address.\n");
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print_hex(Virtual);
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for (;;) {}
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}
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u64 PML4I = GET_PML4_ENTRY(Virtual);
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u64 PDPI = GET_PDP_ENTRY(Virtual);
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u64 DIRI = GET_DIR_ENTRY(Virtual);
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u64 TABI = GET_TAB_ENTRY(Virtual);
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u64 *PDP = (u64 *)(g_PML4[PML4I] & 0xFFFFF000);
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if (PDP == 0)
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{
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PDP = (u64 *)_allocate_frame_4k();
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_zero_paging_structure(PDP);
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g_PML4[PML4I] = ((u64)PDP) | 3;
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}
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u64 *Directory = (u64 *)(PDP[PDPI] & 0xFFFFF000);
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if (Directory == 0)
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{
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Directory = (u64 *)_allocate_frame_4k();
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_zero_paging_structure(Directory);
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PDP[PDPI] = ((u64)Directory) | 3;
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}
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u64 *Table = (u64 *)(Directory[DIRI] & 0xFFFFF000);
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if (Table == 0)
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{
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Table = (u64 *)_allocate_frame_4k();
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_zero_paging_structure(Table);
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Directory[DIRI] = ((u64)Table) | 3;
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}
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Table[TABI] = ((u64)Physical) | 3;
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}
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void paging_map_address(u64 PhysicalStart, u64 VirtualStart, u64 Size)
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{
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if (VirtualStart % 0x1000 || PhysicalStart % 0x1000)
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{
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puts("BUG: Requsted allocation of unaligned address.\n");
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for (;;) {}
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}
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u64 AlignedSize = Size;
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if (AlignedSize % 0x1000)
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AlignedSize = (AlignedSize + 0x1000) & 0xFFFFF000;
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for (u64 i = 0; i < AlignedSize; i += 0x1000)
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{
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paging_map_page(VirtualStart + i, PhysicalStart + i);
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}
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}
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void *paging_allocate(u64 VirtualStart, u64 Size)
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{
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// let's first allocate all the pages for the actual data
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u32 Start = 0;
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for (u64 i = 0; i < Size; i += 0x1000)
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{
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u64 Frame = _allocate_frame_4k();
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if (!Start)
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Start = Frame;
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}
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// and now let's map the data (and allocate frames for mapping structures)
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u32 Frame = Start;
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for (u64 Virtual = VirtualStart; (Virtual - VirtualStart) < Size; Virtual += 0x1000)
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{
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paging_map_page(Virtual, Frame);
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Frame += 0x1000;
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}
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return (void *)Start;
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}
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u32 paging_get_last_frame(void)
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{
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return g_FramePointer;
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}
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void *paging_get_pml4(void)
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{
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return g_PML4;
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} |