2 * Physical memory allocation
3 * Copyright (c) 2001,2003,2004 David H. Hovemeyer <daveho@cs.umd.edu>
4 * Copyright (c) 2003, Jeffrey K. Hollingsworth <hollings@cs.umd.edu>
7 * This is free software. You are permitted to use,
8 * redistribute, and modify it as specified in the file "COPYING".
11 #include <geekos/defs.h>
12 #include <geekos/ktypes.h>
13 #include <geekos/kassert.h>
14 #include <geekos/bootinfo.h>
15 #include <geekos/gdt.h>
16 #include <geekos/screen.h>
17 #include <geekos/int.h>
18 #include <geekos/malloc.h>
19 #include <geekos/string.h>
20 #include <geekos/mem.h>
22 #include <geekos/vmm_sizes.h>
23 #include <geekos/serial.h>
25 /* ----------------------------------------------------------------------
27 * ---------------------------------------------------------------------- */
30 * List of Page structures representing each page of physical memory.
32 struct Page* g_pageList;
35 * Number of pages currently available on the freelist.
37 uint_t g_freePageCount = 0;
39 /* ----------------------------------------------------------------------
40 * Private data and functions
41 * ---------------------------------------------------------------------- */
46 extern int debugFaults;
47 #define Debug(args...) if (debugFaults) Print(args)
50 * List of pages available for allocation.
52 static struct Page_List s_freeList;
55 * Total number of physical pages.
57 int unsigned s_numPages;
60 * Add a range of pages to the inventory of physical memory.
62 static void Add_Page_Range(ulong_t start, ulong_t end, int flags)
66 PrintBoth("Start: %u, End: %u\n", (unsigned int)start, (unsigned int)end);
68 KASSERT(Is_Page_Multiple(start));
69 KASSERT(Is_Page_Multiple(end));
72 //Print("Adding %lu pages\n", (end - start) / PAGE_SIZE);
74 for (addr = start; addr < end; addr += PAGE_SIZE) {
75 // Print("Adding Page at %u\n", (unsigned int)addr);
76 struct Page *page = Get_Page(addr);
80 if (flags == PAGE_AVAIL) {
81 /* Add the page to the freelist */
82 Add_To_Back_Of_Page_List(&s_freeList, page);
84 /* Update free page count */
87 Set_Next_In_Page_List(page, 0);
88 Set_Prev_In_Page_List(page, 0);
92 // Print("%d pages now in freelist\n", g_freePageCount);
96 /* ----------------------------------------------------------------------
98 * ---------------------------------------------------------------------- */
101 * The linker defines this symbol to indicate the end of
102 * the executable image.
107 * Initialize memory management data structures.
108 * Enables the use of Alloc_Page() and Free_Page() functions.
110 void Init_Mem(struct Boot_Info* bootInfo)
112 ulong_t numPages = bootInfo->memSizeKB >> 2;
113 // ulong_t endOfMem = numPages * PAGE_SIZE;
114 unsigned numPageListBytes = sizeof(struct Page) * numPages;
115 ulong_t pageListAddr;
120 KASSERT(bootInfo->memSizeKB > 0);
122 if (bootInfo->memSizeKB != TOP_OF_MEM/1024) {
123 PrintBoth("Kernel compiled for %d KB machine, but machine claims %d KB\n",TOP_OF_MEM/1024,bootInfo->memSizeKB);
124 if (bootInfo->memSizeKB < TOP_OF_MEM/1024) {
125 PrintBoth("Kernel compiled for more memory than machine has. Panicking\n");
131 // if there is not enough memory between START_OF_VM+VM_SIZE and TOP_OF_MEM
132 // to store the kernel and kernel structures, we need to panick
133 PrintBoth("Kernel is not compiled with sufficient memory above the VM to support the memory\n");
138 bootInfo->memSizeKB = TOP_OF_MEM / 1024;
141 * Before we do anything, switch from setup.asm's temporary GDT
142 * to the kernel's permanent GDT.
147 * We'll put the list of Page objects right after the end
148 * of the kernel, and mark it as "kernel". This will bootstrap
149 * us sufficiently that we can start allocating pages and
150 * keeping track of them.
153 // JRL: This is stupid...
154 // with large mem sizes the page list overruns into the ISA
155 // hole. By blind luck this causes an unrelated assertion failure, otherwise
156 // I might never have caught it...
157 // We fix it by moving the page list after the kernel heap...
158 // For now we'll make our own stupid assumption that the mem size
159 // is large enough to accomodate the list in high mem.
161 PrintBoth("Total Memory Size: %u MBytes\n", bootInfo->memSizeKB/1024);
162 PrintBoth("VM Start: %x\n",START_OF_VM);
163 PrintBoth("VM End: %x\n",START_OF_VM+VM_SIZE-1);
166 PrintBoth("Page struct size: %u bytes\n", sizeof(struct Page));
167 PrintBoth("Page List Size: %u bytes\n", numPageListBytes);
170 //pageListAddr = Round_Up_To_Page((ulong_t) &end);
171 //pageListAddr = Round_Up_To_Page(HIGHMEM_START + KERNEL_HEAP_SIZE);
173 // Note that this is now moved to be just above the kernel heap
174 // see defs.h for layout
175 pageListAddr=Round_Up_To_Page(KERNEL_PAGELIST);
177 pageListEnd = Round_Up_To_Page(pageListAddr + numPageListBytes);
179 g_pageList = (struct Page*) pageListAddr;
180 // kernEnd = Round_Up_To_Page(pageListAddr + numPageListBytes);
182 // PAD - Note: I am changing this so that everything through the end of
183 // the VM boot package (bioses/vmxassist) is off limits
184 //kernEnd = Round_Up_To_Page((ulong_t) &end);
185 kernEnd = Round_Up_To_Page(VM_BOOT_PACKAGE_END);
186 s_numPages = numPages;
188 PrintBoth("Pagelist addr: %p\n", g_pageList);
189 PrintBoth("index: %p\n", &g_pageList[3]);
190 PrintBoth("direct offset: %p\n", g_pageList + (sizeof(struct Page) * 2));
191 // PrintBoth("Kernel Size=%lx\n", (kernEnd - KERNEL_START_ADDR));
192 // PrintBoth("Kernel Start=%x\n", KERNEL_START_ADDR);
193 PrintBoth("Kernel End=%lx\n", kernEnd);
194 //PrintBoth("end=%x\n", end);
195 PrintBoth("VM Boot Package Start=%x\n", VM_BOOT_PACKAGE_START);
196 PrintBoth("VM Boot Package End=%x\n", VM_BOOT_PACKAGE_END);
199 * The initial kernel thread and its stack are placed
200 * just beyond the ISA hole.
202 // This is no longer true
203 // KASSERT(ISA_HOLE_END == KERN_THREAD_OBJ);
205 //KASSERT(KERN_THREAD_OBJ==(START_OF_VM+VM_SIZE));
206 //KASSERT(KERN_STACK == KERN_THREAD_OBJ + PAGE_SIZE);
209 * Memory looks like this:
210 * 0 - start: available (might want to preserve BIOS data area)
211 * start - end: kernel
212 * end - ISA_HOLE_START: available
213 * ISA_HOLE_START - ISA_HOLE_END: used by hardware (and ROM BIOS?)
214 * ISA_HOLE_END - HIGHMEM_START: used by initial kernel thread
215 * HIGHMEM_START - end of memory: available
216 * (the kernel heap is located at HIGHMEM_START; any unused memory
217 * beyond that is added to the freelist)
220 // The VM region... 0 .. VM size is out of bounds
221 KASSERT(START_OF_VM==0);
223 Add_Page_Range(START_OF_VM, START_OF_VM+VM_SIZE, PAGE_VM);
224 //PrintBoth("hello1\n");
225 // The kernel is still in low memory at this point, in the VM region
226 // Thus we will mark it as kernel use
227 // Add_Page_Range(KERNEL_START_ADDR, kernEnd, PAGE_KERN);
230 //Add_Page_Range(kernEnd, ISA_HOLE_START, PAGE_AVAIL);
231 // ISA hole remains closed (no actual memory)
232 // Add_Page_Range(ISA_HOLE_START, ISA_HOLE_END, PAGE_HW);
234 //Add_Page_Range(ISA_HOLE_END, HIGHMEM_START, PAGE_ALLOCATED);
235 // Add_Page_Range(HIGHMEM_START, HIGHMEM_START + KERNEL_HEAP_SIZE, PAGE_HEAP);
236 //Add_Page_Range(HIGHMEM_START + KERNEL_HEAP_SIZE, endOfMem, PAGE_AVAIL);
237 /* JRL: move page list after kernel heap */
239 //Now, above the VM region...
241 // Kernel thread object
242 Add_Page_Range(KERNEL_THREAD_OBJECT,KERNEL_THREAD_OBJECT+KERNEL_THREAD_OBJECT_SIZE,PAGE_ALLOCATED);
244 Add_Page_Range(KERNEL_STACK,KERNEL_STACK+KERNEL_STACK_SIZE,PAGE_ALLOCATED);
246 Add_Page_Range(KERNEL_HEAP,KERNEL_HEAP+KERNEL_HEAP_SIZE,PAGE_HEAP);
248 Add_Page_Range(pageListAddr, pageListEnd, PAGE_KERN);
250 Add_Page_Range(pageListEnd,Round_Down_To_Page(FINAL_KERNEL_START), PAGE_AVAIL);
252 Add_Page_Range(Round_Down_To_Page(FINAL_KERNEL_START),Round_Up_To_Page(FINAL_VMBOOTEND+1),PAGE_KERN);
254 // IDT (this should be one page)
255 Add_Page_Range(IDT_LOCATION,TSS_LOCATION,PAGE_KERN);
256 // TSS (this should be one page)
257 Add_Page_Range(TSS_LOCATION,GDT_LOCATION, PAGE_KERN);
258 // GDT (this should be one page)
259 Add_Page_Range(GDT_LOCATION,TOP_OF_MEM, PAGE_KERN);
261 /* Initialize the kernel heap */
262 Init_Heap(KERNEL_HEAP, KERNEL_HEAP_SIZE);
264 PrintBoth("%uKB memory detected, %u pages in freelist, %d bytes in kernel heap\n",
265 bootInfo->memSizeKB, g_freePageCount, KERNEL_HEAP_SIZE);
267 PrintBoth("Memory Layout:\n");
268 PrintBoth("%x to %x - VM\n",START_OF_VM,START_OF_VM+VM_SIZE-1);
269 PrintBoth("%x to %x - INITIAL THREAD\n",KERNEL_THREAD_OBJECT,KERNEL_THREAD_OBJECT+KERNEL_THREAD_OBJECT_SIZE-1);
270 PrintBoth("%x to %x - KERNEL STACK\n",KERNEL_STACK,KERNEL_STACK+KERNEL_STACK_SIZE-1);
271 PrintBoth("%x to %x - KERNEL HEAP\n",KERNEL_HEAP,KERNEL_HEAP+KERNEL_HEAP_SIZE-1);
272 PrintBoth("%lx to %lx - PAGE LIST\n",pageListAddr,pageListEnd-1);
273 PrintBoth("%lx to %x - FREE\n",pageListEnd,FINAL_KERNEL_START-1);
274 PrintBoth("%x to %x - KERNEL CODE\n",FINAL_KERNEL_START,FINAL_KERNEL_END);
275 PrintBoth("%x to %x - VM_KERNEL\n", FINAL_VM_KERNEL_START, FINAL_VM_KERNEL_END);
276 PrintBoth("%x to %x - IDT\n",IDT_LOCATION,TSS_LOCATION-1);
277 PrintBoth("%x to %x - TSS\n",TSS_LOCATION,GDT_LOCATION-1);
278 PrintBoth("%x to %x - GDT\n",GDT_LOCATION,TOP_OF_MEM-1);
284 * Initialize the .bss section of the kernel executable image.
288 extern char BSS_START, BSS_END;
290 /* Fill .bss with zeroes */
291 memset(&BSS_START, '\0', &BSS_END - &BSS_START);
292 PrintBoth("BSS Inited, BSS_START=%x, BSS_END=%x\n",BSS_START,BSS_END);
296 * Allocate a page of physical memory.
298 void* Alloc_Page(void)
303 bool iflag = Begin_Int_Atomic();
305 /* See if we have a free page */
306 if (!Is_Page_List_Empty(&s_freeList)) {
307 /* Remove the first page on the freelist. */
308 page = Get_Front_Of_Page_List(&s_freeList);
309 KASSERT((page->flags & PAGE_ALLOCATED) == 0);
310 Remove_From_Front_Of_Page_List(&s_freeList);
312 /* Mark page as having been allocated. */
313 page->flags |= PAGE_ALLOCATED;
315 result = (void*) Get_Page_Address(page);
318 End_Int_Atomic(iflag);
324 * Free a page of physical memory.
326 void Free_Page(void* pageAddr)
328 ulong_t addr = (ulong_t) pageAddr;
332 iflag = Begin_Int_Atomic();
334 KASSERT(Is_Page_Multiple(addr));
336 /* Get the Page object for this page */
337 page = Get_Page(addr);
338 KASSERT((page->flags & PAGE_ALLOCATED) != 0);
340 /* Clear the allocation bit */
341 page->flags &= ~(PAGE_ALLOCATED);
343 /* Put the page back on the freelist */
344 Add_To_Back_Of_Page_List(&s_freeList, page);
347 End_Int_Atomic(iflag);