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/* See COPYRIGHT for copyright information. */
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#include <inc/x86.h>
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#include <inc/mmu.h>
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#include <inc/error.h>
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#include <inc/string.h>
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#include <inc/assert.h>
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#include <kern/pmap.h>
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#include <kern/kclock.h>
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// These variables are set by i386_detect_memory()
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size_t npages; // Amount of physical memory (in pages)
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static size_t npages_basemem; // Amount of base memory (in pages)
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// These variables are set in mem_init()
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pde_t *kern_pgdir; // Kernel's initial page directory
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struct PageInfo *pages; // Physical page state array
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static struct PageInfo *page_free_list; // Free list of physical pages
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// --------------------------------------------------------------
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// Detect machine's physical memory setup.
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// --------------------------------------------------------------
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static int
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nvram_read(int r)
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{
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return mc146818_read(r) | (mc146818_read(r + 1) << 8);
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}
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static void
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i386_detect_memory(void)
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{
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size_t basemem, extmem, ext16mem, totalmem;
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// Use CMOS calls to measure available base & extended memory.
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// (CMOS calls return results in kilobytes.)
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basemem = nvram_read(NVRAM_BASELO);
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extmem = nvram_read(NVRAM_EXTLO);
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ext16mem = nvram_read(NVRAM_EXT16LO) * 64;
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// Calculate the number of physical pages available in both base
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// and extended memory.
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if (ext16mem)
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totalmem = 16 * 1024 + ext16mem;
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else if (extmem)
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totalmem = 1 * 1024 + extmem;
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else
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totalmem = basemem;
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npages = totalmem / (PGSIZE / 1024);
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npages_basemem = basemem / (PGSIZE / 1024);
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cprintf("Physical memory: %uK available, base = %uK, extended = %uK\n",
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totalmem, basemem, totalmem - basemem);
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}
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// --------------------------------------------------------------
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// Set up memory mappings above UTOP.
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// --------------------------------------------------------------
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static void boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm);
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static void check_page_free_list(bool only_low_memory);
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static void check_page_alloc(void);
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static void check_kern_pgdir(void);
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static physaddr_t check_va2pa(pde_t *pgdir, uintptr_t va);
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static void check_page(void);
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static void check_page_installed_pgdir(void);
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// This simple physical memory allocator is used only while JOS is setting
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// up its virtual memory system. page_alloc() is the real allocator.
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//
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// If n>0, allocates enough pages of contiguous physical memory to hold 'n'
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// bytes. Doesn't initialize the memory. Returns a kernel virtual address.
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//
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// If n==0, returns the address of the next free page without allocating
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// anything.
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//
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// If we're out of memory, boot_alloc should panic.
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// This function may ONLY be used during initialization,
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// before the page_free_list list has been set up.
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static void *
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boot_alloc(uint32_t n)
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{
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static char *nextfree; // virtual address of next byte of free memory
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char *result;
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// Initialize nextfree if this is the first time.
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// 'end' is a magic symbol automatically generated by the linker,
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// which points to the end of the kernel's bss segment:
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// the first virtual address that the linker did *not* assign
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// to any kernel code or global variables.
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if (!nextfree) {
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extern char end[];
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nextfree = ROUNDUP((char *) end, PGSIZE);
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}
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// Allocate a chunk large enough to hold 'n' bytes, then update
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// nextfree. Make sure nextfree is kept aligned
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// to a multiple of PGSIZE.
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//
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// LAB 2: Your code here.
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return NULL;
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}
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// Set up a two-level page table:
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// kern_pgdir is its linear (virtual) address of the root
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//
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// This function only sets up the kernel part of the address space
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// (ie. addresses >= UTOP). The user part of the address space
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// will be set up later.
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//
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// From UTOP to ULIM, the user is allowed to read but not write.
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// Above ULIM the user cannot read or write.
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void
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mem_init(void)
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{
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uint32_t cr0;
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size_t n;
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// Find out how much memory the machine has (npages & npages_basemem).
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i386_detect_memory();
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// Remove this line when you're ready to test this function.
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panic("mem_init: This function is not finished\n");
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//////////////////////////////////////////////////////////////////////
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// create initial page directory.
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kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
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memset(kern_pgdir, 0, PGSIZE);
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//////////////////////////////////////////////////////////////////////
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// Recursively insert PD in itself as a page table, to form
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// a virtual page table at virtual address UVPT.
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// (For now, you don't have understand the greater purpose of the
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// following line.)
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// Permissions: kernel R, user R
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kern_pgdir[PDX(UVPT)] = PADDR(kern_pgdir) | PTE_U | PTE_P;
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//////////////////////////////////////////////////////////////////////
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// Allocate an array of npages 'struct PageInfo's and store it in 'pages'.
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// The kernel uses this array to keep track of physical pages: for
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// each physical page, there is a corresponding struct PageInfo in this
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// array. 'npages' is the number of physical pages in memory. Use memset
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// to initialize all fields of each struct PageInfo to 0.
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// Your code goes here:
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//////////////////////////////////////////////////////////////////////
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// Now that we've allocated the initial kernel data structures, we set
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// up the list of free physical pages. Once we've done so, all further
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// memory management will go through the page_* functions. In
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// particular, we can now map memory using boot_map_region
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// or page_insert
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page_init();
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check_page_free_list(1);
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check_page_alloc();
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check_page();
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//////////////////////////////////////////////////////////////////////
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// Now we set up virtual memory
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//////////////////////////////////////////////////////////////////////
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// Map 'pages' read-only by the user at linear address UPAGES
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// Permissions:
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// - the new image at UPAGES -- kernel R, user R
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// (ie. perm = PTE_U | PTE_P)
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// - pages itself -- kernel RW, user NONE
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// Your code goes here:
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//////////////////////////////////////////////////////////////////////
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// Use the physical memory that 'bootstack' refers to as the kernel
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// stack. The kernel stack grows down from virtual address KSTACKTOP.
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// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
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// to be the kernel stack, but break this into two pieces:
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// * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
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// * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
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// the kernel overflows its stack, it will fault rather than
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// overwrite memory. Known as a "guard page".
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// Permissions: kernel RW, user NONE
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// Your code goes here:
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//////////////////////////////////////////////////////////////////////
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// Map all of physical memory at KERNBASE.
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// Ie. the VA range [KERNBASE, 2^32) should map to
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// the PA range [0, 2^32 - KERNBASE)
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// We might not have 2^32 - KERNBASE bytes of physical memory, but
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// we just set up the mapping anyway.
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// Permissions: kernel RW, user NONE
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// Your code goes here:
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// Check that the initial page directory has been set up correctly.
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check_kern_pgdir();
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// Switch from the minimal entry page directory to the full kern_pgdir
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// page table we just created. Our instruction pointer should be
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// somewhere between KERNBASE and KERNBASE+4MB right now, which is
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// mapped the same way by both page tables.
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//
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// If the machine reboots at this point, you've probably set up your
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// kern_pgdir wrong.
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lcr3(PADDR(kern_pgdir));
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check_page_free_list(0);
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// entry.S set the really important flags in cr0 (including enabling
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// paging). Here we configure the rest of the flags that we care about.
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cr0 = rcr0();
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cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_MP;
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cr0 &= ~(CR0_TS|CR0_EM);
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lcr0(cr0);
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// Some more checks, only possible after kern_pgdir is installed.
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check_page_installed_pgdir();
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}
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// --------------------------------------------------------------
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// Tracking of physical pages.
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// The 'pages' array has one 'struct PageInfo' entry per physical page.
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// Pages are reference counted, and free pages are kept on a linked list.
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// --------------------------------------------------------------
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//
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// Initialize page structure and memory free list.
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// After this is done, NEVER use boot_alloc again. ONLY use the page
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// allocator functions below to allocate and deallocate physical
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// memory via the page_free_list.
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//
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void
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page_init(void)
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{
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// The example code here marks all physical pages as free.
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// However this is not truly the case. What memory is free?
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// 1) Mark physical page 0 as in use.
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// This way we preserve the real-mode IDT and BIOS structures
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// in case we ever need them. (Currently we don't, but...)
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// 2) The rest of base memory, [PGSIZE, npages_basemem * PGSIZE)
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// is free.
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// 3) Then comes the IO hole [IOPHYSMEM, EXTPHYSMEM), which must
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// never be allocated.
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// 4) Then extended memory [EXTPHYSMEM, ...).
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// Some of it is in use, some is free. Where is the kernel
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// in physical memory? Which pages are already in use for
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// page tables and other data structures?
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//
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// Change the code to reflect this.
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// NB: DO NOT actually touch the physical memory corresponding to
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// free pages!
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size_t i;
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for (i = 0; i < npages; i++) {
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pages[i].pp_ref = 0;
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pages[i].pp_link = page_free_list;
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page_free_list = &pages[i];
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}
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}
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//
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// Allocates a physical page. If (alloc_flags & ALLOC_ZERO), fills the entire
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// returned physical page with '\0' bytes. Does NOT increment the reference
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// count of the page - the caller must do these if necessary (either explicitly
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// or via page_insert).
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//
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// Be sure to set the pp_link field of the allocated page to NULL so
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// page_free can check for double-free bugs.
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//
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// Returns NULL if out of free memory.
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//
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// Hint: use page2kva and memset
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struct PageInfo *
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page_alloc(int alloc_flags)
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{
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// Fill this function in
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return 0;
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}
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//
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// Return a page to the free list.
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// (This function should only be called when pp->pp_ref reaches 0.)
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//
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void
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page_free(struct PageInfo *pp)
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{
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// Fill this function in
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// Hint: You may want to panic if pp->pp_ref is nonzero or
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// pp->pp_link is not NULL.
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}
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//
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// Decrement the reference count on a page,
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// freeing it if there are no more refs.
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//
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void
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page_decref(struct PageInfo* pp)
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{
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if (--pp->pp_ref == 0)
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page_free(pp);
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}
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// Given 'pgdir', a pointer to a page directory, pgdir_walk returns
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// a pointer to the page table entry (PTE) for linear address 'va'.
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// This requires walking the two-level page table structure.
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//
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// The relevant page table page might not exist yet.
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// If this is true, and create == false, then pgdir_walk returns NULL.
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// Otherwise, pgdir_walk allocates a new page table page with page_alloc.
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// - If the allocation fails, pgdir_walk returns NULL.
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// - Otherwise, the new page's reference count is incremented,
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// the page is cleared,
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// and pgdir_walk returns a pointer into the new page table page.
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//
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// Hint 1: you can turn a PageInfo * into the physical address of the
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// page it refers to with page2pa() from kern/pmap.h.
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//
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// Hint 2: the x86 MMU checks permission bits in both the page directory
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// and the page table, so it's safe to leave permissions in the page
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// directory more permissive than strictly necessary.
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|
|
|
//
|
|
|
|
|
// Hint 3: look at inc/mmu.h for useful macros that manipulate page
|
|
|
|
|
// table and page directory entries.
|
|
|
|
|
//
|
|
|
|
|
pte_t *
|
|
|
|
|
pgdir_walk(pde_t *pgdir, const void *va, int create)
|
|
|
|
|
{
|
|
|
|
|
// Fill this function in
|
|
|
|
|
return NULL;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Map [va, va+size) of virtual address space to physical [pa, pa+size)
|
|
|
|
|
// in the page table rooted at pgdir. Size is a multiple of PGSIZE, and
|
|
|
|
|
// va and pa are both page-aligned.
|
|
|
|
|
// Use permission bits perm|PTE_P for the entries.
|
|
|
|
|
//
|
|
|
|
|
// This function is only intended to set up the ``static'' mappings
|
|
|
|
|
// above UTOP. As such, it should *not* change the pp_ref field on the
|
|
|
|
|
// mapped pages.
|
|
|
|
|
//
|
|
|
|
|
// Hint: the TA solution uses pgdir_walk
|
|
|
|
|
static void
|
|
|
|
|
boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm)
|
|
|
|
|
{
|
|
|
|
|
// Fill this function in
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Map the physical page 'pp' at virtual address 'va'.
|
|
|
|
|
// The permissions (the low 12 bits) of the page table entry
|
|
|
|
|
// should be set to 'perm|PTE_P'.
|
|
|
|
|
//
|
|
|
|
|
// Requirements
|
|
|
|
|
// - If there is already a page mapped at 'va', it should be page_remove()d.
|
|
|
|
|
// - If necessary, on demand, a page table should be allocated and inserted
|
|
|
|
|
// into 'pgdir'.
|
|
|
|
|
// - pp->pp_ref should be incremented if the insertion succeeds.
|
|
|
|
|
// - The TLB must be invalidated if a page was formerly present at 'va'.
|
|
|
|
|
//
|
|
|
|
|
// Corner-case hint: Make sure to consider what happens when the same
|
|
|
|
|
// pp is re-inserted at the same virtual address in the same pgdir.
|
|
|
|
|
// However, try not to distinguish this case in your code, as this
|
|
|
|
|
// frequently leads to subtle bugs; there's an elegant way to handle
|
|
|
|
|
// everything in one code path.
|
|
|
|
|
//
|
|
|
|
|
// RETURNS:
|
|
|
|
|
// 0 on success
|
|
|
|
|
// -E_NO_MEM, if page table couldn't be allocated
|
|
|
|
|
//
|
|
|
|
|
// Hint: The TA solution is implemented using pgdir_walk, page_remove,
|
|
|
|
|
// and page2pa.
|
|
|
|
|
//
|
|
|
|
|
int
|
|
|
|
|
page_insert(pde_t *pgdir, struct PageInfo *pp, void *va, int perm)
|
|
|
|
|
{
|
|
|
|
|
// Fill this function in
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Return the page mapped at virtual address 'va'.
|
|
|
|
|
// If pte_store is not zero, then we store in it the address
|
|
|
|
|
// of the pte for this page. This is used by page_remove and
|
|
|
|
|
// can be used to verify page permissions for syscall arguments,
|
|
|
|
|
// but should not be used by most callers.
|
|
|
|
|
//
|
|
|
|
|
// Return NULL if there is no page mapped at va.
|
|
|
|
|
//
|
|
|
|
|
// Hint: the TA solution uses pgdir_walk and pa2page.
|
|
|
|
|
//
|
|
|
|
|
struct PageInfo *
|
|
|
|
|
page_lookup(pde_t *pgdir, void *va, pte_t **pte_store)
|
|
|
|
|
{
|
|
|
|
|
// Fill this function in
|
|
|
|
|
return NULL;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Unmaps the physical page at virtual address 'va'.
|
|
|
|
|
// If there is no physical page at that address, silently does nothing.
|
|
|
|
|
//
|
|
|
|
|
// Details:
|
|
|
|
|
// - The ref count on the physical page should decrement.
|
|
|
|
|
// - The physical page should be freed if the refcount reaches 0.
|
|
|
|
|
// - The pg table entry corresponding to 'va' should be set to 0.
|
|
|
|
|
// (if such a PTE exists)
|
|
|
|
|
// - The TLB must be invalidated if you remove an entry from
|
|
|
|
|
// the page table.
|
|
|
|
|
//
|
|
|
|
|
// Hint: The TA solution is implemented using page_lookup,
|
|
|
|
|
// tlb_invalidate, and page_decref.
|
|
|
|
|
//
|
|
|
|
|
void
|
|
|
|
|
page_remove(pde_t *pgdir, void *va)
|
|
|
|
|
{
|
|
|
|
|
// Fill this function in
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Invalidate a TLB entry, but only if the page tables being
|
|
|
|
|
// edited are the ones currently in use by the processor.
|
|
|
|
|
//
|
|
|
|
|
void
|
|
|
|
|
tlb_invalidate(pde_t *pgdir, void *va)
|
|
|
|
|
{
|
|
|
|
|
// Flush the entry only if we're modifying the current address space.
|
|
|
|
|
// For now, there is only one address space, so always invalidate.
|
|
|
|
|
invlpg(va);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// --------------------------------------------------------------
|
|
|
|
|
// Checking functions.
|
|
|
|
|
// --------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Check that the pages on the page_free_list are reasonable.
|
|
|
|
|
//
|
|
|
|
|
static void
|
|
|
|
|
check_page_free_list(bool only_low_memory)
|
|
|
|
|
{
|
|
|
|
|
struct PageInfo *pp;
|
|
|
|
|
unsigned pdx_limit = only_low_memory ? 1 : NPDENTRIES;
|
|
|
|
|
int nfree_basemem = 0, nfree_extmem = 0;
|
|
|
|
|
char *first_free_page;
|
|
|
|
|
|
|
|
|
|
if (!page_free_list)
|
|
|
|
|
panic("'page_free_list' is a null pointer!");
|
|
|
|
|
|
|
|
|
|
if (only_low_memory) {
|
|
|
|
|
// Move pages with lower addresses first in the free
|
|
|
|
|
// list, since entry_pgdir does not map all pages.
|
|
|
|
|
struct PageInfo *pp1, *pp2;
|
|
|
|
|
struct PageInfo **tp[2] = { &pp1, &pp2 };
|
|
|
|
|
for (pp = page_free_list; pp; pp = pp->pp_link) {
|
|
|
|
|
int pagetype = PDX(page2pa(pp)) >= pdx_limit;
|
|
|
|
|
*tp[pagetype] = pp;
|
|
|
|
|
tp[pagetype] = &pp->pp_link;
|
|
|
|
|
}
|
|
|
|
|
*tp[1] = 0;
|
|
|
|
|
*tp[0] = pp2;
|
|
|
|
|
page_free_list = pp1;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// if there's a page that shouldn't be on the free list,
|
|
|
|
|
// try to make sure it eventually causes trouble.
|
|
|
|
|
for (pp = page_free_list; pp; pp = pp->pp_link)
|
|
|
|
|
if (PDX(page2pa(pp)) < pdx_limit)
|
|
|
|
|
memset(page2kva(pp), 0x97, 128);
|
|
|
|
|
|
|
|
|
|
first_free_page = (char *) boot_alloc(0);
|
|
|
|
|
for (pp = page_free_list; pp; pp = pp->pp_link) {
|
|
|
|
|
// check that we didn't corrupt the free list itself
|
|
|
|
|
assert(pp >= pages);
|
|
|
|
|
assert(pp < pages + npages);
|
|
|
|
|
assert(((char *) pp - (char *) pages) % sizeof(*pp) == 0);
|
|
|
|
|
|
|
|
|
|
// check a few pages that shouldn't be on the free list
|
|
|
|
|
assert(page2pa(pp) != 0);
|
|
|
|
|
assert(page2pa(pp) != IOPHYSMEM);
|
|
|
|
|
assert(page2pa(pp) != EXTPHYSMEM - PGSIZE);
|
|
|
|
|
assert(page2pa(pp) != EXTPHYSMEM);
|
|
|
|
|
assert(page2pa(pp) < EXTPHYSMEM || (char *) page2kva(pp) >= first_free_page);
|
|
|
|
|
|
|
|
|
|
if (page2pa(pp) < EXTPHYSMEM)
|
|
|
|
|
++nfree_basemem;
|
|
|
|
|
else
|
|
|
|
|
++nfree_extmem;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
assert(nfree_basemem > 0);
|
|
|
|
|
assert(nfree_extmem > 0);
|
|
|
|
|
|
|
|
|
|
cprintf("check_page_free_list() succeeded!\n");
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Check the physical page allocator (page_alloc(), page_free(),
|
|
|
|
|
// and page_init()).
|
|
|
|
|
//
|
|
|
|
|
static void
|
|
|
|
|
check_page_alloc(void)
|
|
|
|
|
{
|
|
|
|
|
struct PageInfo *pp, *pp0, *pp1, *pp2;
|
|
|
|
|
int nfree;
|
|
|
|
|
struct PageInfo *fl;
|
|
|
|
|
char *c;
|
|
|
|
|
int i;
|
|
|
|
|
|
|
|
|
|
if (!pages)
|
|
|
|
|
panic("'pages' is a null pointer!");
|
|
|
|
|
|
|
|
|
|
// check number of free pages
|
|
|
|
|
for (pp = page_free_list, nfree = 0; pp; pp = pp->pp_link)
|
|
|
|
|
++nfree;
|
|
|
|
|
|
|
|
|
|
// should be able to allocate three pages
|
|
|
|
|
pp0 = pp1 = pp2 = 0;
|
|
|
|
|
assert((pp0 = page_alloc(0)));
|
|
|
|
|
assert((pp1 = page_alloc(0)));
|
|
|
|
|
assert((pp2 = page_alloc(0)));
|
|
|
|
|
|
|
|
|
|
assert(pp0);
|
|
|
|
|
assert(pp1 && pp1 != pp0);
|
|
|
|
|
assert(pp2 && pp2 != pp1 && pp2 != pp0);
|
|
|
|
|
assert(page2pa(pp0) < npages*PGSIZE);
|
|
|
|
|
assert(page2pa(pp1) < npages*PGSIZE);
|
|
|
|
|
assert(page2pa(pp2) < npages*PGSIZE);
|
|
|
|
|
|
|
|
|
|
// temporarily steal the rest of the free pages
|
|
|
|
|
fl = page_free_list;
|
|
|
|
|
page_free_list = 0;
|
|
|
|
|
|
|
|
|
|
// should be no free memory
|
|
|
|
|
assert(!page_alloc(0));
|
|
|
|
|
|
|
|
|
|
// free and re-allocate?
|
|
|
|
|
page_free(pp0);
|
|
|
|
|
page_free(pp1);
|
|
|
|
|
page_free(pp2);
|
|
|
|
|
pp0 = pp1 = pp2 = 0;
|
|
|
|
|
assert((pp0 = page_alloc(0)));
|
|
|
|
|
assert((pp1 = page_alloc(0)));
|
|
|
|
|
assert((pp2 = page_alloc(0)));
|
|
|
|
|
assert(pp0);
|
|
|
|
|
assert(pp1 && pp1 != pp0);
|
|
|
|
|
assert(pp2 && pp2 != pp1 && pp2 != pp0);
|
|
|
|
|
assert(!page_alloc(0));
|
|
|
|
|
|
|
|
|
|
// test flags
|
|
|
|
|
memset(page2kva(pp0), 1, PGSIZE);
|
|
|
|
|
page_free(pp0);
|
|
|
|
|
assert((pp = page_alloc(ALLOC_ZERO)));
|
|
|
|
|
assert(pp && pp0 == pp);
|
|
|
|
|
c = page2kva(pp);
|
|
|
|
|
for (i = 0; i < PGSIZE; i++)
|
|
|
|
|
assert(c[i] == 0);
|
|
|
|
|
|
|
|
|
|
// give free list back
|
|
|
|
|
page_free_list = fl;
|
|
|
|
|
|
|
|
|
|
// free the pages we took
|
|
|
|
|
page_free(pp0);
|
|
|
|
|
page_free(pp1);
|
|
|
|
|
page_free(pp2);
|
|
|
|
|
|
|
|
|
|
// number of free pages should be the same
|
|
|
|
|
for (pp = page_free_list; pp; pp = pp->pp_link)
|
|
|
|
|
--nfree;
|
|
|
|
|
assert(nfree == 0);
|
|
|
|
|
|
|
|
|
|
cprintf("check_page_alloc() succeeded!\n");
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
//
|
|
|
|
|
// Checks that the kernel part of virtual address space
|
|
|
|
|
// has been set up roughly correctly (by mem_init()).
|
|
|
|
|
//
|
|
|
|
|
// This function doesn't test every corner case,
|
|
|
|
|
// but it is a pretty good sanity check.
|
|
|
|
|
//
|
|
|
|
|
|
|
|
|
|
static void
|
|
|
|
|
check_kern_pgdir(void)
|
|
|
|
|
{
|
|
|
|
|
uint32_t i, n;
|
|
|
|
|
pde_t *pgdir;
|
|
|
|
|
|
|
|
|
|
pgdir = kern_pgdir;
|
|
|
|
|
|
|
|
|
|
// check pages array
|
|
|
|
|
n = ROUNDUP(npages*sizeof(struct PageInfo), PGSIZE);
|
|
|
|
|
for (i = 0; i < n; i += PGSIZE)
|
|
|
|
|
assert(check_va2pa(pgdir, UPAGES + i) == PADDR(pages) + i);
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// check phys mem
|
|
|
|
|
for (i = 0; i < npages * PGSIZE; i += PGSIZE)
|
|
|
|
|
assert(check_va2pa(pgdir, KERNBASE + i) == i);
|
|
|
|
|
|
|
|
|
|
// check kernel stack
|
|
|
|
|
for (i = 0; i < KSTKSIZE; i += PGSIZE)
|
|
|
|
|
assert(check_va2pa(pgdir, KSTACKTOP - KSTKSIZE + i) == PADDR(bootstack) + i);
|
|
|
|
|
assert(check_va2pa(pgdir, KSTACKTOP - PTSIZE) == ~0);
|
|
|
|
|
|
|
|
|
|
// check PDE permissions
|
|
|
|
|
for (i = 0; i < NPDENTRIES; i++) {
|
|
|
|
|
switch (i) {
|
|
|
|
|
case PDX(UVPT):
|
|
|
|
|
case PDX(KSTACKTOP-1):
|
|
|
|
|
case PDX(UPAGES):
|
|
|
|
|
assert(pgdir[i] & PTE_P);
|
|
|
|
|
break;
|
|
|
|
|
default:
|
|
|
|
|
if (i >= PDX(KERNBASE)) {
|
|
|
|
|
assert(pgdir[i] & PTE_P);
|
|
|
|
|
assert(pgdir[i] & PTE_W);
|
|
|
|
|
} else
|
|
|
|
|
assert(pgdir[i] == 0);
|
|
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
cprintf("check_kern_pgdir() succeeded!\n");
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// This function returns the physical address of the page containing 'va',
|
|
|
|
|
// defined by the page directory 'pgdir'. The hardware normally performs
|
|
|
|
|
// this functionality for us! We define our own version to help check
|
|
|
|
|
// the check_kern_pgdir() function; it shouldn't be used elsewhere.
|
|
|
|
|
|
|
|
|
|
static physaddr_t
|
|
|
|
|
check_va2pa(pde_t *pgdir, uintptr_t va)
|
|
|
|
|
{
|
|
|
|
|
pte_t *p;
|
|
|
|
|
|
|
|
|
|
pgdir = &pgdir[PDX(va)];
|
|
|
|
|
if (!(*pgdir & PTE_P))
|
|
|
|
|
return ~0;
|
|
|
|
|
p = (pte_t*) KADDR(PTE_ADDR(*pgdir));
|
|
|
|
|
if (!(p[PTX(va)] & PTE_P))
|
|
|
|
|
return ~0;
|
|
|
|
|
return PTE_ADDR(p[PTX(va)]);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// check page_insert, page_remove, &c
|
|
|
|
|
static void
|
|
|
|
|
check_page(void)
|
|
|
|
|
{
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struct PageInfo *pp, *pp0, *pp1, *pp2;
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struct PageInfo *fl;
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pte_t *ptep, *ptep1;
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void *va;
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int i;
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extern pde_t entry_pgdir[];
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// should be able to allocate three pages
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pp0 = pp1 = pp2 = 0;
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assert((pp0 = page_alloc(0)));
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assert((pp1 = page_alloc(0)));
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assert((pp2 = page_alloc(0)));
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assert(pp0);
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assert(pp1 && pp1 != pp0);
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assert(pp2 && pp2 != pp1 && pp2 != pp0);
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// temporarily steal the rest of the free pages
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fl = page_free_list;
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page_free_list = 0;
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// should be no free memory
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assert(!page_alloc(0));
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// there is no page allocated at address 0
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assert(page_lookup(kern_pgdir, (void *) 0x0, &ptep) == NULL);
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// there is no free memory, so we can't allocate a page table
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assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) < 0);
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// free pp0 and try again: pp0 should be used for page table
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page_free(pp0);
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assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) == 0);
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assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
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assert(check_va2pa(kern_pgdir, 0x0) == page2pa(pp1));
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assert(pp1->pp_ref == 1);
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assert(pp0->pp_ref == 1);
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// should be able to map pp2 at PGSIZE because pp0 is already allocated for page table
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assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
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assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
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assert(pp2->pp_ref == 1);
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// should be no free memory
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assert(!page_alloc(0));
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// should be able to map pp2 at PGSIZE because it's already there
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assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
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assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
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assert(pp2->pp_ref == 1);
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// pp2 should NOT be on the free list
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// could happen in ref counts are handled sloppily in page_insert
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assert(!page_alloc(0));
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// check that pgdir_walk returns a pointer to the pte
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ptep = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(PGSIZE)]));
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assert(pgdir_walk(kern_pgdir, (void*)PGSIZE, 0) == ptep+PTX(PGSIZE));
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// should be able to change permissions too.
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assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W|PTE_U) == 0);
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assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
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assert(pp2->pp_ref == 1);
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assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U);
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assert(kern_pgdir[0] & PTE_U);
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// should be able to remap with fewer permissions
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assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
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assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_W);
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assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
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// should not be able to map at PTSIZE because need free page for page table
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assert(page_insert(kern_pgdir, pp0, (void*) PTSIZE, PTE_W) < 0);
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// insert pp1 at PGSIZE (replacing pp2)
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assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W) == 0);
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assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
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// should have pp1 at both 0 and PGSIZE, pp2 nowhere, ...
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assert(check_va2pa(kern_pgdir, 0) == page2pa(pp1));
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assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
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// ... and ref counts should reflect this
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assert(pp1->pp_ref == 2);
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assert(pp2->pp_ref == 0);
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// pp2 should be returned by page_alloc
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assert((pp = page_alloc(0)) && pp == pp2);
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// unmapping pp1 at 0 should keep pp1 at PGSIZE
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page_remove(kern_pgdir, 0x0);
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assert(check_va2pa(kern_pgdir, 0x0) == ~0);
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assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
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assert(pp1->pp_ref == 1);
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assert(pp2->pp_ref == 0);
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// test re-inserting pp1 at PGSIZE
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assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, 0) == 0);
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assert(pp1->pp_ref);
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assert(pp1->pp_link == NULL);
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// unmapping pp1 at PGSIZE should free it
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page_remove(kern_pgdir, (void*) PGSIZE);
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assert(check_va2pa(kern_pgdir, 0x0) == ~0);
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assert(check_va2pa(kern_pgdir, PGSIZE) == ~0);
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assert(pp1->pp_ref == 0);
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assert(pp2->pp_ref == 0);
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// so it should be returned by page_alloc
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assert((pp = page_alloc(0)) && pp == pp1);
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// should be no free memory
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assert(!page_alloc(0));
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// forcibly take pp0 back
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assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
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kern_pgdir[0] = 0;
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assert(pp0->pp_ref == 1);
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pp0->pp_ref = 0;
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// check pointer arithmetic in pgdir_walk
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page_free(pp0);
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va = (void*)(PGSIZE * NPDENTRIES + PGSIZE);
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ptep = pgdir_walk(kern_pgdir, va, 1);
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ptep1 = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(va)]));
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assert(ptep == ptep1 + PTX(va));
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kern_pgdir[PDX(va)] = 0;
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pp0->pp_ref = 0;
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// check that new page tables get cleared
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memset(page2kva(pp0), 0xFF, PGSIZE);
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page_free(pp0);
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pgdir_walk(kern_pgdir, 0x0, 1);
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ptep = (pte_t *) page2kva(pp0);
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for(i=0; i<NPTENTRIES; i++)
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assert((ptep[i] & PTE_P) == 0);
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kern_pgdir[0] = 0;
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pp0->pp_ref = 0;
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// give free list back
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page_free_list = fl;
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// free the pages we took
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page_free(pp0);
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page_free(pp1);
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page_free(pp2);
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cprintf("check_page() succeeded!\n");
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}
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// check page_insert, page_remove, &c, with an installed kern_pgdir
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static void
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check_page_installed_pgdir(void)
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{
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struct PageInfo *pp, *pp0, *pp1, *pp2;
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struct PageInfo *fl;
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pte_t *ptep, *ptep1;
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uintptr_t va;
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int i;
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// check that we can read and write installed pages
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pp1 = pp2 = 0;
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assert((pp0 = page_alloc(0)));
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assert((pp1 = page_alloc(0)));
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assert((pp2 = page_alloc(0)));
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page_free(pp0);
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memset(page2kva(pp1), 1, PGSIZE);
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memset(page2kva(pp2), 2, PGSIZE);
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page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W);
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assert(pp1->pp_ref == 1);
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assert(*(uint32_t *)PGSIZE == 0x01010101U);
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page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W);
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assert(*(uint32_t *)PGSIZE == 0x02020202U);
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assert(pp2->pp_ref == 1);
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assert(pp1->pp_ref == 0);
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*(uint32_t *)PGSIZE = 0x03030303U;
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assert(*(uint32_t *)page2kva(pp2) == 0x03030303U);
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page_remove(kern_pgdir, (void*) PGSIZE);
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assert(pp2->pp_ref == 0);
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// forcibly take pp0 back
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assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
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kern_pgdir[0] = 0;
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assert(pp0->pp_ref == 1);
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pp0->pp_ref = 0;
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// free the pages we took
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page_free(pp0);
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cprintf("check_page_installed_pgdir() succeeded!\n");
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}
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Anish Athalye