Mercurial > lcfOS
annotate cos/kernel/mm.c @ 299:674789d9ff37
Added a doc
| author | Windel Bouwman |
|---|---|
| date | Sun, 01 Dec 2013 18:37:23 +0100 |
| parents | 35cc54e078dd |
| children |
| rev | line source |
|---|---|
| 28 | 1 /* Memory manager functions, |
| 2 * | |
| 3 * Uses a bitmap to keep track of 4k pages that are in use. | |
| 4 * | |
| 5 * */ | |
| 26 | 6 |
| 7 #include "kernel.h" | |
| 8 | |
| 40 | 9 #define HEAP_START 0xC000000000000000 |
| 10 #define HEAP_INITIAL_SIZE 0x100000 | |
| 11 | |
| 37 | 12 // Bitmap that keeps track of all the 4 kB memory pages in the system: |
| 29 | 13 static uint64_t *frames = 0; |
| 14 static uint64_t nframes = 0; | |
| 26 | 15 |
| 29 | 16 memmap_t* kernel_map = 0; // kernel memory mapping |
| 40 | 17 // TODO: determine if this is required. |
| 29 | 18 memmap_t* current_map = 0; // The currently active memory mapping |
| 19 | |
| 40 | 20 heap_t* kernel_heap = 0; |
| 21 | |
| 29 | 22 static void set_frame(uint64_t frame) |
| 26 | 23 { |
| 24 uint64_t idx = frame / 64; | |
| 25 uint64_t off = frame % 64; | |
| 26 frames[idx] |= (0x1 << off); | |
| 27 } | |
| 28 | |
| 29 | 29 static void clear_frame(uint64_t frame) |
| 26 | 30 { |
| 31 uint64_t idx = frame / 64; | |
| 32 uint64_t off = frame % 64; | |
| 33 frames[idx] &= ~(0x1 << off); | |
| 34 } | |
| 35 | |
| 36 uint64_t test_frame(uint64_t frame) | |
| 37 { | |
| 38 uint64_t idx = frame / 64; | |
| 39 uint64_t off = frame % 64; | |
| 40 return (frames[idx] & (0x1 << off)); | |
| 41 } | |
| 42 | |
| 29 | 43 static uint64_t first_frame() |
| 26 | 44 { |
| 45 uint64_t i, j; | |
| 28 | 46 for (i = 0; i < nframes / 64; i++) |
| 26 | 47 { |
| 48 if (frames[i] != 0xFFFFFFFFFFFFFFFF) | |
| 49 { | |
| 50 for (j = 0; j < 64; j++) | |
| 51 { | |
| 52 uint64_t dut = 0x1 << j; | |
| 53 if ((frames[i] & dut) != dut) | |
| 54 { | |
| 55 return i*64+j; | |
| 56 } | |
| 57 } | |
| 58 } | |
| 59 } | |
| 29 | 60 |
| 61 // No frame found: | |
| 62 return (uint64_t) -1; | |
| 26 | 63 } |
| 64 | |
| 40 | 65 void memory_status(void) |
| 66 { | |
| 67 // Determine amount of used memory. | |
| 68 uint64_t i, j; | |
| 69 uint64_t inuse = 0; | |
| 70 for (i = 0; i < nframes / 64; i++) | |
| 71 { | |
| 72 for (j = 0; j < 64; j++) | |
| 73 { | |
| 74 if ((frames[i] & (1UL<<j)) == (1UL<<j)) | |
| 75 { | |
| 76 inuse++; | |
| 77 } | |
| 78 } | |
| 79 } | |
| 80 printf("Memory: %d, in use: %d\n", nframes/0x100, inuse/0x100); | |
| 81 } | |
| 82 | |
| 37 | 83 /* |
| 84 * Initializes the memory manager, allocating a bitmap once. | |
| 85 */ | |
| 28 | 86 void init_memory(uint64_t total_mem_size) |
| 87 { | |
| 37 | 88 printf("Running with %d MB ram\n", total_mem_size / 1000000); |
| 89 | |
| 40 | 90 // Memory size is from address 0x100000 |
| 91 total_mem_size += 0x100000; | |
| 92 | |
|
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3a6a9b929db0
Added initial ramdisk and some virtual file system functions
windel
parents:
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changeset
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93 // Only here placement malloc is used! |
|
3a6a9b929db0
Added initial ramdisk and some virtual file system functions
windel
parents:
30
diff
changeset
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94 // |
| 37 | 95 // Allocate and clear bits to remember which 4KiB-frames are in use: |
| 40 | 96 // Calculate number of frames. memory size is indicated from address 0x100000 |
| 97 nframes = (total_mem_size) / 0x1000; // Calculate number of frames | |
| 98 int numbytes = ((nframes / 64) + 1) * sizeof(uint64_t); | |
| 99 frames = (uint64_t*)kmalloc(numbytes); | |
| 100 memset(frames, 0, numbytes); | |
| 29 | 101 |
| 102 // Create kernel map: | |
| 40 | 103 kernel_map = (memmap_t*)kmalloc_a(sizeof(memmap_t)); |
| 29 | 104 memset(kernel_map, 0, sizeof(memmap_t)); |
| 105 | |
| 106 // Identity map lower memory and mark as used by the kernel. | |
| 107 // Mark as used by the kernel: | |
| 108 uint64_t i; | |
| 109 i = 0; | |
| 40 | 110 while ( i <= placement_address + 0x100000) |
| 29 | 111 { |
| 112 page_t *page; | |
| 113 | |
| 114 page = get_page(i, kernel_map); // Get page for address | |
| 115 page->address = i >> 12; // Set the address of this page. | |
| 116 page->present = 1; | |
| 117 page->rw = 1; | |
| 118 page->us = 1; // Make all things accessable for users for now. | |
| 30 | 119 //page->pwt = 1; // Is this bit required? |
| 29 | 120 |
| 121 set_frame(i / 0x1000); | |
| 122 | |
| 123 i += 0x1000; // Increase a 4 k frame | |
| 124 } | |
| 125 | |
| 126 // Set the created mapping as active: | |
| 41 | 127 switch_mapping(kernel_map); // Loads cr3 |
| 30 | 128 |
| 29 | 129 // TODO: set the use of placement malloc to invalid after here. |
| 40 | 130 // kernel_heap = create_heap(HEAP_START, HEAP_INITIAL_SIZE); |
| 28 | 131 } |
| 132 | |
| 29 | 133 void alloc_frame(page_t *page) |
| 26 | 134 { |
| 29 | 135 if (page->address != 0) |
| 136 { | |
| 137 return; | |
| 138 } | |
| 26 | 139 uint64_t idx = first_frame(); |
| 140 if (idx == (uint64_t) -1) | |
| 141 { | |
| 142 panic("No more memory!"); | |
| 143 } | |
| 144 set_frame(idx); | |
| 29 | 145 |
| 146 page->present = 1; | |
| 147 page->rw = 1; | |
| 148 page->us = 0; | |
| 149 page->address = idx; // set address in frame number, the byte address is 0x1000 times this value. | |
| 26 | 150 } |
| 151 | |
| 28 | 152 void free_frame(page_t *page) |
| 153 { | |
| 29 | 154 clear_frame(page->address / 0x1000); |
| 155 page->address = 0; | |
| 156 page->present = 0; | |
| 157 } | |
| 158 | |
| 159 void switch_mapping(memmap_t* mapping) | |
| 160 { | |
| 161 current_map = mapping; | |
| 162 | |
| 40 | 163 // Load table address: |
| 29 | 164 asm volatile("mov %0, %%cr3" :: "r"(&mapping->table)); |
| 165 | |
| 166 // Enable paging (and flush cache): | |
| 167 uint64_t cr0; | |
| 168 asm volatile("mov %%cr0, %0": "=r"(cr0)); | |
| 169 cr0 |= 0x80000000; | |
| 170 asm volatile("mov %0, %%cr0":: "r"(cr0)); | |
| 28 | 171 } |
| 26 | 172 |
| 29 | 173 /* Get a page for a virtual address, and create other tables if required */ |
| 174 page_t* get_page(uint64_t address, memmap_t *mapping) | |
| 175 { | |
| 176 // Retrieve the correct PDP (page dir pointer table): | |
| 177 uint64_t pml4index = (address >> 39) & 0x1FF; | |
| 178 PDPT_t *pdpt = 0; | |
| 179 if (mapping->table[pml4index].present == 1) | |
| 180 { | |
| 181 pdpt = (PDPT_t*)((uint64_t)mapping->table[pml4index].address << 12); | |
| 182 } | |
| 183 else | |
| 184 { | |
| 185 // Create new table: | |
| 40 | 186 printf("Get page for address %x\n", address); |
| 187 // TODO: make sure that this function calls kmalloc instead of placement malloc. | |
| 188 pdpt = (PDPT_t*)kmalloc_a(sizeof(PDPT_t)); | |
| 29 | 189 memset(pdpt, 0, sizeof(PDPT_t)); |
| 190 | |
| 191 // TODO: get function like virt2phys or something here | |
| 192 uint64_t address = (uint64_t)pdpt; // get the physical address | |
| 193 mapping->table[pml4index].address = address >> 12; // shift right | |
| 194 mapping->table[pml4index].rw = 1; | |
| 195 mapping->table[pml4index].us = 1; | |
| 196 mapping->table[pml4index].present = 1; | |
| 197 } | |
| 198 | |
| 199 uint64_t pdptindex = (address >> 30) & 0x1FF; | |
| 200 // Retrieve the correct page directory: | |
| 201 PD_t *pd = 0; | |
| 202 if (pdpt->table[pdptindex].present == 1) | |
| 203 { | |
| 204 pd = (PD_t*)((uint64_t)pdpt->table[pdptindex].address << 12); | |
| 205 } | |
| 206 else | |
| 207 { | |
| 208 // Create a new table: | |
| 40 | 209 pd = (PD_t*)kmalloc_a(sizeof(PD_t)); |
| 29 | 210 memset(pd, 0, sizeof(PD_t)); |
| 211 | |
| 212 // Enter table into PDPT: | |
| 213 // TODO: make virt2phys function: | |
| 214 uint64_t address = (uint64_t)pd; | |
| 215 pdpt->table[pdptindex].address = address >> 12; | |
| 216 pdpt->table[pdptindex].rw = 1; | |
| 217 pdpt->table[pdptindex].us = 1; | |
| 218 pdpt->table[pdptindex].present = 1; | |
| 219 } | |
| 220 | |
| 221 // Retrieve the correct page table: | |
| 222 uint64_t pdindex = (address >> 21) & 0x1FF; | |
| 223 PT_t *pt = 0; | |
| 224 if (pd->table[pdindex].present == 1) | |
| 225 { | |
| 226 pt = (PT_t*)((uint64_t)pd->table[pdindex].address << 12); | |
| 227 } | |
| 228 else | |
| 229 { | |
| 230 // Create table: | |
| 40 | 231 pt = (PT_t*)kmalloc_a(sizeof(PD_t)); |
| 29 | 232 memset(pt, 0, sizeof(PT_t)); |
| 233 | |
| 234 // Enter PT into PD: | |
| 235 uint64_t address = (uint64_t)pt; | |
| 236 pd->table[pdindex].address = address >> 12; | |
| 237 pd->table[pdindex].rw = 1; | |
| 238 pd->table[pdindex].us = 1; | |
| 239 pd->table[pdindex].present = 1; | |
| 240 } | |
| 241 | |
| 242 // Finally get the page from the directory: | |
| 243 // TODO: convert from physical address to virtual address: | |
| 244 uint64_t ptindex = (address >> 12) & 0x1FF; | |
| 245 return &pt->table[ptindex]; | |
| 246 } | |
| 247 |