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>
24 #include <geekos/debug.h>
26 /* ----------------------------------------------------------------------
28 * ---------------------------------------------------------------------- */
31 * List of Page structures representing each page of physical memory.
33 struct Page* g_pageList;
36 * Number of pages currently available on the freelist.
38 uint_t g_freePageCount = 0;
40 /* ----------------------------------------------------------------------
41 * Private data and functions
42 * ---------------------------------------------------------------------- */
47 extern int debugFaults;
48 #define Debug(args...) if (debugFaults) Print(args)
51 * List of pages available for allocation.
53 static struct Page_List s_freeList;
56 * Total number of physical pages.
58 int unsigned s_numPages;
61 * Add a range of pages to the inventory of physical memory.
63 static void Add_Page_Range(ulong_t start, ulong_t end, int flags)
67 PrintBoth("Start: %u, End: %u\n", (unsigned int)start, (unsigned int)end);
69 KASSERT(Is_Page_Multiple(start));
70 KASSERT(Is_Page_Multiple(end));
73 //Print("Adding %lu pages\n", (end - start) / PAGE_SIZE);
75 for (addr = start; addr < end; addr += PAGE_SIZE) {
76 // Print("Adding Page at %u\n", (unsigned int)addr);
77 struct Page *page = Get_Page(addr);
81 if (flags == PAGE_AVAIL) {
82 /* Add the page to the freelist */
83 Add_To_Back_Of_Page_List(&s_freeList, page);
85 /* Update free page count */
88 Set_Next_In_Page_List(page, 0);
89 Set_Prev_In_Page_List(page, 0);
93 // Print("%d pages now in freelist\n", g_freePageCount);
97 /* ----------------------------------------------------------------------
99 * ---------------------------------------------------------------------- */
102 * The linker defines this symbol to indicate the end of
103 * the executable image.
108 * Initialize memory management data structures.
109 * Enables the use of Alloc_Page() and Free_Page() functions.
111 void Init_Mem(struct Boot_Info* bootInfo)
113 ulong_t numPages = bootInfo->memSizeKB >> 2;
114 // ulong_t endOfMem = numPages * PAGE_SIZE;
115 unsigned numPageListBytes = sizeof(struct Page) * numPages;
116 ulong_t pageListAddr;
121 KASSERT(bootInfo->memSizeKB > 0);
123 if (bootInfo->memSizeKB != TOP_OF_MEM/1024) {
124 PrintBoth("Kernel compiled for %d KB machine, but machine claims %d KB\n",TOP_OF_MEM/1024,bootInfo->memSizeKB);
125 if (bootInfo->memSizeKB < TOP_OF_MEM/1024) {
126 PrintBoth("Kernel compiled for more memory than machine has. Panicking\n");
132 // if there is not enough memory between START_OF_VM+VM_SIZE and TOP_OF_MEM
133 // to store the kernel and kernel structures, we need to panick
134 PrintBoth("Kernel is not compiled with sufficient memory above the VM to support the memory\n");
139 bootInfo->memSizeKB = TOP_OF_MEM / 1024;
142 * Before we do anything, switch from setup.asm's temporary GDT
143 * to the kernel's permanent GDT.
148 * We'll put the list of Page objects right after the end
149 * of the kernel, and mark it as "kernel". This will bootstrap
150 * us sufficiently that we can start allocating pages and
151 * keeping track of them.
154 // JRL: This is stupid...
155 // with large mem sizes the page list overruns into the ISA
156 // hole. By blind luck this causes an unrelated assertion failure, otherwise
157 // I might never have caught it...
158 // We fix it by moving the page list after the kernel heap...
159 // For now we'll make our own stupid assumption that the mem size
160 // is large enough to accomodate the list in high mem.
162 PrintBoth("Total Memory Size: %u MBytes\n", bootInfo->memSizeKB/1024);
163 PrintBoth("VM Start: %x\n",START_OF_VM);
164 PrintBoth("VM End: %x\n",START_OF_VM+VM_SIZE-1);
167 PrintBoth("Page struct size: %lu bytes\n", sizeof(struct Page));
168 PrintBoth("Page List Size: %u bytes\n", numPageListBytes);
171 //pageListAddr = Round_Up_To_Page((ulong_t) &end);
172 //pageListAddr = Round_Up_To_Page(HIGHMEM_START + KERNEL_HEAP_SIZE);
174 // Note that this is now moved to be just above the kernel heap
175 // see defs.h for layout
176 pageListAddr=Round_Up_To_Page(KERNEL_PAGELIST);
178 pageListEnd = Round_Up_To_Page(pageListAddr + numPageListBytes);
180 g_pageList = (struct Page*) pageListAddr;
181 // kernEnd = Round_Up_To_Page(pageListAddr + numPageListBytes);
183 // PAD - Note: I am changing this so that everything through the end of
184 // the VM boot package (bioses/vmxassist) is off limits
185 //kernEnd = Round_Up_To_Page((ulong_t) &end);
186 kernEnd = Round_Up_To_Page(VM_BOOT_PACKAGE_END);
187 s_numPages = numPages;
189 PrintBoth("Pagelist addr: %p\n", g_pageList);
190 PrintBoth("index: %p\n", &g_pageList[3]);
191 PrintBoth("direct offset: %p\n", g_pageList + (sizeof(struct Page) * 2));
192 // PrintBoth("Kernel Size=%lx\n", (kernEnd - KERNEL_START_ADDR));
193 // PrintBoth("Kernel Start=%x\n", KERNEL_START_ADDR);
194 PrintBoth("Kernel End=%lx\n", kernEnd);
195 //PrintBoth("end=%x\n", end);
196 PrintBoth("VM Boot Package Start=%x\n", VM_BOOT_PACKAGE_START);
197 PrintBoth("VM Boot Package End=%x\n", VM_BOOT_PACKAGE_END);
200 * The initial kernel thread and its stack are placed
201 * just beyond the ISA hole.
203 // This is no longer true
204 // KASSERT(ISA_HOLE_END == KERN_THREAD_OBJ);
206 //KASSERT(KERN_THREAD_OBJ==(START_OF_VM+VM_SIZE));
207 //KASSERT(KERN_STACK == KERN_THREAD_OBJ + PAGE_SIZE);
210 * Memory looks like this:
211 * 0 - start: available (might want to preserve BIOS data area)
212 * start - end: kernel
213 * end - ISA_HOLE_START: available
214 * ISA_HOLE_START - ISA_HOLE_END: used by hardware (and ROM BIOS?)
215 * ISA_HOLE_END - HIGHMEM_START: used by initial kernel thread
216 * HIGHMEM_START - end of memory: available
217 * (the kernel heap is located at HIGHMEM_START; any unused memory
218 * beyond that is added to the freelist)
221 // The VM region... 0 .. VM size is out of bounds
222 KASSERT(START_OF_VM==0);
224 Add_Page_Range(START_OF_VM, START_OF_VM+VM_SIZE, PAGE_VM);
225 //PrintBoth("hello1\n");
226 // The kernel is still in low memory at this point, in the VM region
227 // Thus we will mark it as kernel use
228 // Add_Page_Range(KERNEL_START_ADDR, kernEnd, PAGE_KERN);
231 //Add_Page_Range(kernEnd, ISA_HOLE_START, PAGE_AVAIL);
232 // ISA hole remains closed (no actual memory)
233 // Add_Page_Range(ISA_HOLE_START, ISA_HOLE_END, PAGE_HW);
235 //Add_Page_Range(ISA_HOLE_END, HIGHMEM_START, PAGE_ALLOCATED);
236 // Add_Page_Range(HIGHMEM_START, HIGHMEM_START + KERNEL_HEAP_SIZE, PAGE_HEAP);
237 //Add_Page_Range(HIGHMEM_START + KERNEL_HEAP_SIZE, endOfMem, PAGE_AVAIL);
238 /* JRL: move page list after kernel heap */
240 //Now, above the VM region...
242 // Kernel thread object
243 Add_Page_Range(KERNEL_THREAD_OBJECT,KERNEL_THREAD_OBJECT+KERNEL_THREAD_OBJECT_SIZE,PAGE_ALLOCATED);
245 Add_Page_Range(KERNEL_STACK,KERNEL_STACK+KERNEL_STACK_SIZE,PAGE_ALLOCATED);
247 Add_Page_Range(KERNEL_HEAP,KERNEL_HEAP+KERNEL_HEAP_SIZE,PAGE_HEAP);
249 Add_Page_Range(pageListAddr, pageListEnd, PAGE_KERN);
251 Add_Page_Range(pageListEnd,Round_Down_To_Page(FINAL_KERNEL_START), PAGE_AVAIL);
253 Add_Page_Range(Round_Down_To_Page(FINAL_KERNEL_START),Round_Up_To_Page(FINAL_VMBOOTEND+1),PAGE_KERN);
255 // IDT (this should be one page)
256 Add_Page_Range(IDT_LOCATION,TSS_LOCATION,PAGE_KERN);
257 // TSS (this should be one page)
258 Add_Page_Range(TSS_LOCATION,GDT_LOCATION, PAGE_KERN);
259 // GDT (this should be one page)
260 Add_Page_Range(GDT_LOCATION,TOP_OF_MEM, PAGE_KERN);
262 /* Initialize the kernel heap */
263 Init_Heap(KERNEL_HEAP, KERNEL_HEAP_SIZE);
265 PrintBoth("%uKB memory detected, %u pages in freelist, %d bytes in kernel heap\n",
266 bootInfo->memSizeKB, g_freePageCount, KERNEL_HEAP_SIZE);
268 PrintBoth("Memory Layout:\n");
269 PrintBoth("%x to %x - VM\n",START_OF_VM,START_OF_VM+VM_SIZE-1);
270 PrintBoth("%x to %x - INITIAL THREAD\n",KERNEL_THREAD_OBJECT,KERNEL_THREAD_OBJECT+KERNEL_THREAD_OBJECT_SIZE-1);
271 PrintBoth("%x to %x - KERNEL STACK\n",KERNEL_STACK,KERNEL_STACK+KERNEL_STACK_SIZE-1);
272 PrintBoth("%x to %x - KERNEL HEAP\n",KERNEL_HEAP,KERNEL_HEAP+KERNEL_HEAP_SIZE-1);
273 PrintBoth("%lx to %lx - PAGE LIST\n",pageListAddr,pageListEnd-1);
274 PrintBoth("%lx to %x - FREE\n",pageListEnd,FINAL_KERNEL_START-1);
275 PrintBoth("%x to %x - KERNEL CODE\n",FINAL_KERNEL_START,FINAL_KERNEL_END);
276 PrintBoth("%x to %x - VM_KERNEL\n", FINAL_VM_KERNEL_START, FINAL_VM_KERNEL_END);
277 PrintBoth("%x to %x - IDT\n",IDT_LOCATION,TSS_LOCATION-1);
278 PrintBoth("%x to %x - TSS\n",TSS_LOCATION,GDT_LOCATION-1);
279 PrintBoth("%x to %x - GDT\n",GDT_LOCATION,TOP_OF_MEM-1);
285 * Initialize the .bss section of the kernel executable image.
289 extern char BSS_START, BSS_END;
291 /* Fill .bss with zeroes */
292 memset(&BSS_START, '\0', &BSS_END - &BSS_START);
293 PrintBoth("BSS Inited, BSS_START=%x, BSS_END=%x\n",BSS_START,BSS_END);
297 * Allocate a page of physical memory.
299 void* Alloc_Page(void)
304 bool iflag = Begin_Int_Atomic();
306 /* See if we have a free page */
307 if (!Is_Page_List_Empty(&s_freeList)) {
308 /* Remove the first page on the freelist. */
309 page = Get_Front_Of_Page_List(&s_freeList);
310 KASSERT((page->flags & PAGE_ALLOCATED) == 0);
311 Remove_From_Front_Of_Page_List(&s_freeList);
313 /* Mark page as having been allocated. */
314 page->flags |= PAGE_ALLOCATED;
316 result = (void*) Get_Page_Address(page);
319 End_Int_Atomic(iflag);
325 * Free a page of physical memory.
327 void Free_Page(void* pageAddr)
329 ulong_t addr = (ulong_t) pageAddr;
333 iflag = Begin_Int_Atomic();
335 KASSERT(Is_Page_Multiple(addr));
337 /* Get the Page object for this page */
338 page = Get_Page(addr);
339 KASSERT((page->flags & PAGE_ALLOCATED) != 0);
341 /* Clear the allocation bit */
342 page->flags &= ~(PAGE_ALLOCATED);
344 /* Put the page back on the freelist */
345 Add_To_Back_Of_Page_List(&s_freeList, page);
348 End_Int_Atomic(iflag);