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-rw-r--r--kernel/vm.c945
1 files changed, 0 insertions, 945 deletions
diff --git a/kernel/vm.c b/kernel/vm.c
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-/**
-** @file vm.c
-**
-** @author CSCI-452 class of 20245
-**
-** @brief Kernel VM support
-*/
-
-#define KERNEL_SRC
-
-#include <common.h>
-
-#include <vm.h>
-#include <vmtables.h>
-
-#include <kmem.h>
-#include <procs.h>
-#include <x86/arch.h>
-#include <x86/ops.h>
-
-/*
-** PUBLIC GLOBAL VARIABLES
-*/
-
-// created page directory for the kernel
-pde_t *kpdir;
-
-/*
-** PRIVATE FUNCTIONS
-*/
-
-/**
-** Name: vm_isr
-**
-** Description: Page fault handler
-**
-** @param vector Interrupt vector number
-** @param code Error code pushed onto the stack
-*/
-static void vm_isr(int vector, int code)
-{
- // get whatever information we can from the fault
- pfec_t fault;
- fault.u = (uint32_t)code;
- uint32_t addr = r_cr2();
-
- // report what we found
- sprint(b256,
- "** page fault @ 0x%08x %cP %c %cM %cRSV %c %cPK %cSS %cHLAT %cSGZ",
- addr, fault.s.p ? ' ' : '!', fault.s.w ? 'W' : 'R',
- fault.s.us ? 'U' : 'S', fault.s.rsvd ? ' ' : '!',
- fault.s.id ? 'I' : 'D', fault.s.pk ? ' ' : '!',
- fault.s.ss ? ' ' : '!', fault.s.hlat ? ' ' : '!',
- fault.s.sgz ? ' ' : '!');
-
- // and give up
- PANIC(0, b256);
-}
-
-/**
-** Name: ptcount
-**
-** Count the number of each type of entry in a page table.
-** Returns a 32-bit result containing two 16-bit counts:
-**
-** Upper half Lower half
-** PDIR: # of 4MB entries # of 'present' entries
-** PMT: zero # of 'present' entries
-**
-** The number of "not present" can be calculated from these.
-**
-** @param pt Pointer to the page table
-** @param dir Is it a page directory (vs. a page table)?
-*/
-ATTR_UNUSED
-static uint32_t ptcount(pte_t *ptr, bool_t dir)
-{
- uint16_t n_np = 0, n_p = 0, n_lg = 0;
-
- for (int i = 0; i < N_PTE; ++i) {
- pde_t entry = *ptr++;
- if (!IS_PRESENT(entry)) {
- ++n_np;
- continue;
- }
- if (dir && IS_LARGE(entry)) {
- ++n_lg;
- } else {
- ++n_p;
- }
- }
-
- // n_lg will be 0 for PMTs
- return (n_lg << 16) | n_p;
-}
-
-// decode a PDE
-static void pde_prt(uint32_t level, uint32_t i, uint32_t entry, bool_t all)
-{
- if (!IS_PRESENT(entry) && !all) {
- return;
- }
-
- // indent
- for (int n = 0; n <= level; ++n)
- cio_puts(" ");
-
- // line header
- cio_printf("[%03x] %08x", i, entry);
-
- // perms
- if (IS_LARGE(entry)) { // PS is 1
- if ((entry & PDE_PAT) != 0)
- cio_puts(" PAT");
- if ((entry & PDE_G) != 0)
- cio_puts(" G");
- cio_puts(" PS");
- if ((entry & PDE_D) != 0)
- cio_puts(" D");
- }
- if ((entry & PDE_A) != 0)
- cio_puts(" A");
- if ((entry & PDE_PCD) != 0)
- cio_puts(" CD");
- if ((entry & PDE_PWT) != 0)
- cio_puts(" WT");
- if ((entry & PDE_US) != 0)
- cio_puts(" U");
- if ((entry & PDE_RW) != 0)
- cio_puts(" W");
-
- // frame address
- cio_printf(" P --> %s %08x\n", IS_LARGE(entry) ? "Pg" : "PT",
- PDE_ADDR(entry));
-}
-
-// decode a PTE
-static void pte_prt(uint32_t level, uint32_t i, uint32_t entry, bool_t all)
-{
- if (!IS_PRESENT(entry) && !all) {
- return;
- }
-
- // indent
- for (int n = 0; n <= level; ++n)
- cio_puts(" ");
-
- // line header
- cio_printf("[%03x] %08x", i, entry);
-
- // perms
- if ((entry & PTE_G) != 0)
- cio_puts(" G");
- if ((entry & PTE_PAT) != 0)
- cio_puts(" PAT");
- if ((entry & PTE_D) != 0)
- cio_puts(" D");
- if ((entry & PTE_A) != 0)
- cio_puts(" A");
- if ((entry & PTE_PCD) != 0)
- cio_puts(" CD");
- if ((entry & PTE_PWT) != 0)
- cio_puts(" WT");
- if ((entry & PTE_US) != 0)
- cio_puts(" U");
- if ((entry & PTE_RW) != 0)
- cio_puts(" W");
-
- cio_printf(" P --> Pg %08x\n", PTE_ADDR(entry));
-}
-
-/**
-** Name: ptdump
-**
-** Recursive helper for table hierarchy dump.
-**
-** @param level Current hierarchy level
-** @param pt Page table to display
-** @param dir Is it a page directory (vs. a page table)?
-** @param mode How to display the entries
-*/
-ATTR_UNUSED
-static void ptdump(uint_t level, void *pt, bool_t dir, enum vmmode_e mode)
-{
- pte_t *ptr = (pte_t *)pt;
-
- // indent two spaces per level
- for (int n = 0; n < level; ++n)
- cio_puts(" ");
-
- cio_printf("%s at 0x%08x:", dir ? "PDir" : "PTbl", (uint32_t)pt);
- uint32_t nums = ptcount(ptr, dir);
- if (dir) {
- cio_printf(" 4MB=%u", (nums >> 16));
- }
- cio_printf(" P=%u !P=%u\n", nums & 0xffff,
- N_PTE - ((nums >> 16) + (nums & 0xffff)));
-
- for (uint32_t i = 0; i < (uint32_t)N_PTE; ++i) {
- pte_t entry = *ptr++;
-
- // only process this entry if it's not empty
- if (entry) {
- if (dir) {
- // this is a PDIR entry; could be either a 4MB
- // page, or a PMT pointer
- if (mode > Simple) {
- pde_prt(level, i, entry, false);
- if (!IS_LARGE(entry) && mode > OneLevel) {
- ptdump(level + 1, (void *)P2V(PTE_ADDR(entry)), false,
- mode);
- }
- }
- } else {
- // just a PMT entry
- if (mode > Simple) {
- pte_prt(level, i, entry, false);
- }
- }
- }
- }
-}
-
-/**
-** Name: pmt_dump
-**
-** Dump the non-zero entries of a page table or directory
-**
-** @param pt The page table
-** @param dir Is this a page directory?
-** @param start First entry to process
-** @param num Number of entries to process
-*/
-ATTR_UNUSED
-static void pmt_dump(pte_t *pt, bool_t dir, uint32_t start, uint32_t num)
-{
- cio_printf("\n\nP%c dump", dir ? 'D' : 'T');
- cio_printf(" of %08x", (uint32_t)pt);
- cio_printf(" [%03x] through [%03x]\n", start, start + num - 1);
-
- uint_t n = 0;
- uint_t z = 0;
-
- for (uint_t i = 0; i < num; ++i) {
- pte_t entry = pt[start + i];
- // four entries per line
- if (n && ((n & 0x3) == 0)) {
- cio_putchar('\n');
- }
- if (IS_PRESENT(entry)) {
- cio_printf(" %03x", start + i);
- if (IS_LARGE(entry)) {
- cio_printf(" 8 %05x", GET_4MFRAME(entry) << 10);
- } else {
- cio_printf(" 4 %05x", GET_4KFRAME(entry));
- }
- ++n;
- } else {
- ++z;
- }
- // pause after every four lines of output
- if (n && ((n & 0xf) == 0)) {
- delay(DELAY_2_SEC);
- }
- }
-
- // partial line?
- if ((n & 0x3) != 0) {
- cio_putchar('\n');
- }
-
- if (z > 0) {
- cio_printf(" %u entries were !P\n", z);
- }
-
- delay(DELAY_2_SEC);
-}
-
-/*
-** PUBLIC FUNCTIONS
-*/
-
-/**
-** Name: vm_init
-**
-** Description: Initialize the VM module
-*/
-void vm_init(void)
-{
-#if TRACING_INIT
- cio_puts(" VM");
-#endif
-
- // set up the kernel's 4K-page directory
- kpdir = vm_mkkvm();
- assert(kpdir != NULL);
-
-#if TRACING_VM
- cio_printf("vm_init: kpdir %08x, adding user pages\n", kpdir);
-#endif
-
- // add the entries for the user address space
- for (uint32_t addr = 0; addr < NUM_4MB; addr += SZ_PAGE) {
- int stat = vm_map(kpdir, (void *)addr, addr, SZ_PAGE, PTE_US | PTE_RW);
- if (stat != SUCCESS) {
- cio_printf("vm_init, map %08x->%08x failed, status %d\n", addr,
- addr, stat);
- PANIC(0, "vm_init user range map failed");
- }
-#if TRACING_VM
- cio_putchar('.');
-#endif
- }
-#if TRACING_VM
- cio_puts(" done\n");
-#endif
-
- // switch to it
- vm_set_kvm();
-
-#if TRACING_VM
- cio_puts("vm_init: running on new kpdir\n");
-#endif
-
- // install the page fault handler
- install_isr(VEC_PAGE_FAULT, vm_isr);
-}
-
-/**
-** Name: vm_uva2kva
-**
-** Convert a user VA into a kernel address. Works for all addresses -
-** if the address is a page address, the low-order nine bits will be
-** zeroes; otherwise, they are the offset into the page, which is
-** unchanged between the address spaces.
-**
-** @param pdir Pointer to the page directory to examine
-** @param va Virtual address to check
-*/
-void *vm_uva2kva(pde_t *pdir, void *va)
-{
- // find the PMT entry for this address
- pte_t *pte = vm_getpte(pdir, va, false);
- if (pte == NULL) {
- return NULL;
- }
-
- // get the entry
- pte_t entry = *pte;
-
- // is this a valid address for the user?
- if (!IS_PRESENT(entry)) {
- return NULL;
- }
-
- // is this a system-only page?
- if (IS_SYSTEM(entry)) {
- return NULL;
- }
-
- // get the physical address
- uint32_t frame = PTE_ADDR(*pte) | PERMS(va);
-
- return (void *)P2V(frame);
-}
-
-/**
-** Name: vm_pagedup
-**
-** Duplicate a page of memory
-**
-** @param old Pointer to the first byte of a page
-**
-** @return a pointer to the new, duplicate page, or NULL
-*/
-void *vm_pagedup(void *old)
-{
- void *new = (void *)km_page_alloc();
- if (new != NULL) {
- blkmov(new, old, SZ_PAGE);
- }
- return new;
-}
-
-/**
-** Name: vm_pdedup
-**
-** Duplicate a page directory entry
-**
-** @param entry The entry to be duplicated
-**
-** @return the new entry, or -1 on error
-*/
-pde_t vm_pdedup(pde_t entry)
-{
-#if TRACING_VM
- cio_printf("vm_pdedup curr %08x\n", (uint32_t)entry);
-#endif
-
- // simplest case
- if (!IS_PRESENT(entry)) {
- return 0;
- }
-
- // is this a large page?
- if (IS_LARGE(entry)) {
- // just copy it
- return entry;
- }
-
- // OK, we have a 4KB entry; allocate a page table for it
- pte_t *tblva = (pte_t *)km_page_alloc();
- if (tblva == NULL) {
- return (uint32_t)-1;
- }
-
- // make sure the entries are all initially 'not present'
- memclr(tblva, SZ_PAGE);
-
- // VA of the page table for this directory entry
- pte_t *old = (pte_t *)P2V(PDE_ADDR(entry));
-
- // pointer to the first PTE in the new table (already a VA)
- pte_t *new = tblva;
-
- for (int i = 0; i < N_PTE; ++i) {
- // only need to copy 'present' entries
- if (IS_PRESENT(*old)) {
- *new = *old;
- }
- ++old;
- ++new;
- }
-
- // replace the page table address
- // (PA of page table, lower 12 bits from '*curr')
- return (pde_t)(V2P(PTE_ADDR(tblva)) | PERMS(entry));
-}
-
-/**
-** Name: vm_getpte
-**
-** Return the address of the PTE corresponding to the virtual address
-** 'va' within the address space controlled by 'pgdir'. If there is no
-** page table for that VA and 'alloc' is true, create the necessary
-** page table entries.
-**
-** @param pdir Pointer to the page directory to be searched
-** @param va The virtual address we're looking for
-** @param alloc Should we allocate a page table if there isn't one?
-**
-** @return A pointer to the page table entry for this VA, or NULL if
-** there isn't one and we're not allocating
-*/
-pte_t *vm_getpte(pde_t *pdir, const void *va, bool_t alloc)
-{
- pte_t *ptbl;
-
- // sanity check
- assert1(pdir != NULL);
-
- // get the PDIR entry for this virtual address
- pde_t *pde_ptr = &pdir[PDIX(va)];
-
- // is it already set up?
- if (IS_PRESENT(*pde_ptr)) {
- // yes!
- ptbl = (pte_t *)P2V(PTE_ADDR(*pde_ptr));
-
- } else {
- // no - should we create it?
- if (!alloc) {
- // nope, so just return
- return NULL;
- }
-
- // yes - try to allocate a page table
- ptbl = (pte_t *)km_page_alloc();
- if (ptbl == NULL) {
- WARNING("can't allocate page table");
- return NULL;
- }
-
- // who knows what was left in this page....
- memclr(ptbl, SZ_PAGE);
-
- // add this to the page directory
- //
- // we set this up to allow general access; this could be
- // controlled by setting access control in the page table
- // entries, if necessary.
- //
- // NOTE: the allocator is serving us virtual page addresses,
- // so we must convert them to physical addresses for the
- // table entries
- *pde_ptr = V2P(ptbl) | PDE_P | PDE_RW | PDE_US;
- }
-
- // finally, return a pointer to the entry in the page table for this VA
- return &ptbl[PTIX(va)];
-}
-
-// Set up kernel part of a page table.
-pde_t *vm_mkkvm(void)
-{
- mapping_t *k;
-
- // allocate the page directory
- pde_t *pdir = km_page_alloc();
- if (pdir == NULL) {
- return NULL;
- }
-#if 0 && TRACING_VM
- cio_puts( "\nEntering vm_mkkvm\n" );
- pmt_dump( pdir, true, 0, N_PDE );
-#endif
-
- // clear it out to disable all the entries
- memclr(pdir, SZ_PAGE);
-
- if (P2V(PHYS_TOP) > DEV_BASE) {
- cio_printf("PHYS_TOP (%08x -> %08x) > DEV_BASE(%08x)\n", PHYS_TOP,
- P2V(PHYS_TOP), DEV_BASE);
- PANIC(0, "PHYS_TOP too large");
- }
-
- // map in all the page ranges
- k = kmap;
- for (int i = 0; i < n_kmap; ++i, ++k) {
- int stat = vm_map(pdir, ((void *)k->va_start), k->pa_start,
- k->pa_end - k->pa_start, k->perm);
- if (stat != SUCCESS) {
- vm_free(pdir);
- return 0;
- }
- }
-#if 0 && TRACING_VM
- cio_puts( "\nvm_mkkvm() final PD:\n" );
- pmt_dump( pdir, true, 0, 16 );
- pmt_dump( pdir, true, 0x200, 16 );
-#endif
-
- return pdir;
-}
-
-/*
-** Creates an initial user VM table hierarchy by copying the
-** system entries into a new page directory.
-**
-** @return a pointer to the new page directory, or NULL
-*/
-pde_t *vm_mkuvm(void)
-{
- // allocate the directory
- pde_t *new = (pde_t *)km_page_alloc();
- if (new == NULL) {
- return NULL;
- }
-
- // iterate through the 'system' portions of the kernel
- // page directory
- int i = PDIX(KERN_BASE);
- pde_t *curr = &kpdir[i];
- pde_t *dst = &new[i];
- while (i < N_PDE) {
- if (*curr != 0) {
- // found an active one - duplicate it
- pde_t entry = vm_pdedup(*curr);
- if (entry == (uint32_t)-1) {
- return NULL;
- }
- *dst = entry;
- } else {
- *dst = 0;
- }
-
- ++curr;
- ++dst;
- ++i;
- }
-
- return new;
-}
-
-/**
-** Name: vm_set_kvm
-**
-** Switch the page table register to the kernel's page directory.
-*/
-void vm_set_kvm(void)
-{
-#if TRACING_VM
- cio_puts("Entering vm_set_kvm()\n");
-#endif
- w_cr3(V2P(kpdir)); // switch to the kernel page table
-#if TRACING_VM
- cio_puts("Exiting vm_set_kvm()\n");
-#endif
-}
-
-/**
-** Name: vm_set_uvm
-**
-** Switch the page table register to the page directory for a user process.
-**
-** @param p PCB of the process we're switching to
-*/
-void vm_set_uvm(pcb_t *p)
-{
-#if TRACING_VM
- cio_puts("Entering vm_set_uvm()\n");
-#endif
- assert(p != NULL);
- assert(p->pdir != NULL);
-
- w_cr3(V2P(p->pdir)); // switch to process's address space
-#if TRACING_VM
- cio_puts("Entering vm_set_uvm()\n");
-#endif
-}
-
-/**
-** Name: vm_add
-**
-** Add pages to the page hierarchy for a process, copying data into
-** them if necessary.
-**
-** @param pdir Pointer to the page directory to modify
-** @param wr "Writable" flag for the PTE
-** @param sys "System" flag for the PTE
-** @param va Starting VA of the range
-** @param size Amount of physical memory to allocate (bytes)
-** @param data Pointer to data to copy, or NULL
-** @param bytes Number of bytes to copy
-**
-** @return status of the allocation attempt
-*/
-int vm_add(pde_t *pdir, bool_t wr, bool_t sys, void *va, uint32_t size,
- char *data, uint32_t bytes)
-{
- // how many pages do we need?
- uint32_t npages = ((size & MOD4K_BITS) ? PGUP(size) : size) >> MOD4K_SHIFT;
-
- // permission set for the PTEs
- uint32_t entrybase = PTE_P;
- if (wr) {
- entrybase |= PTE_RW;
- }
- if (!sys) {
- entrybase |= PTE_US;
- }
-
-#if TRACING_VM
- cio_printf("vm_add: pdir %08x, %s, va %08x size %u (%u pgs)\n",
- (uint32_t)pdir, wr ? "W" : "!W", (uint32_t)va, size, npages);
- cio_printf(" from %08x, %u bytes, perms %08x\n", (uint32_t)data,
- bytes, entrybase);
-#endif
-
- // iterate through the pages
-
- for (int i = 0; i < npages; ++i) {
- // figure out where this page will go in the hierarchy
- pte_t *pte = vm_getpte(pdir, va, true);
- if (pte == NULL) {
- // if i > 0, this isn't the first frame - is
- // there anything to do about other frames?
- // POSSIBLE MEMORY LEAK?
- return E_NO_MEMORY;
- }
-
- // allocate the frame
- void *page = km_page_alloc();
- if (page == NULL) {
- // same question here
- return E_NO_MEMORY;
- }
-
- // clear it all out
- memclr(page, SZ_PAGE);
-
- // create the PTE for this frame
- uint32_t entry = (uint32_t)(V2P(PTE_ADDR(page)) | entrybase);
- *pte = entry;
-
- // copy data if we need to
- if (data != NULL && bytes > 0) {
- // how much to copy
- uint32_t num = bytes > SZ_PAGE ? SZ_PAGE : bytes;
- // do it!
- memmove((void *)page, (void *)data, num);
- // adjust all the pointers
- data += num; // where to continue
- bytes -= num; // what's left to copy
- }
-
- // bump the virtual address
- va += SZ_PAGE;
- }
-
- return SUCCESS;
-}
-
-/**
-** Name: vm_free
-**
-** Deallocate a page table hierarchy and all physical memory frames
-** in the user portion.
-**
-** Works only for 4KB pages.
-**
-** @param pdir Pointer to the page directory
-*/
-void vm_free(pde_t *pdir)
-{
-#if TRACING_VM
- cio_printf("vm_free(%08x)\n", (uint32_t)pdir);
-#endif
-
- // do we have anything to do?
- if (pdir == NULL) {
- return;
- }
-
- // iterate through the page directory entries, freeing the
- // PMTS and the frames they point to
- pde_t *curr = pdir;
- int nf = 0;
- int nt = 0;
-
- for (int i = 0; i < N_PDE; ++i) {
- // the entry itself
- pde_t entry = *curr;
-
- // does this entry point to anything useful?
- if (IS_PRESENT(entry)) {
- // yes - large pages make us unhappy
- assert(!IS_LARGE(entry));
-
- // get the PMT pointer
- pte_t *pmt = (pte_t *)P2V(PTE_ADDR(entry));
-
- // walk the PMT
- for (int j = 0; j < N_PTE; ++j) {
- pte_t tmp = *pmt;
- // does this entry point to a frame?
- if (IS_PRESENT(tmp)) {
- // yes - free the frame
- km_page_free((void *)P2V(PTE_ADDR(tmp)));
- ++nf;
- // mark it so we don't get surprised
- *pmt = 0;
- }
- // move on
- ++pmt;
- }
- // now, free the PMT itself
- km_page_free((void *)P2V(PDE_ADDR(entry)));
- ++nt;
- *curr = 0;
- }
-
- // move to the next entry
- ++curr;
- }
-
- // finally, free the PDIR itself
- km_page_free((void *)pdir);
- ++nt;
-
-#if TRACING_VM
- cio_printf("vm_free: %d pages, %d tables\n", nf, nt);
-#endif
-}
-
-/*
-** Name: vm_map
-**
-** Create PTEs for virtual addresses starting at 'va' that refer to
-** physical addresses in the range [pa, pa+size-1]. We aren't guaranteed
-** that va is page-aligned.
-**
-** @param pdir Page directory for this address space
-** @param va The starting virtual address
-** @param pa The starting physical address
-** @param size Length of the range to be mapped
-** @param perm Permission bits for the PTEs
-**
-** @return the status of the mapping attempt
-*/
-int vm_map(pde_t *pdir, void *va, uint32_t pa, uint32_t size, int perm)
-{
- // round the VA down to its page boundary
- char *addr = (char *)PGDOWN((uint32_t)va);
-
- // round the end of the range down to its page boundary
- char *last = (char *)PGDOWN(((uint32_t)va) + size - 1);
-
-#if TRACING_VM
- cio_printf("vm_map pdir %08x va %08x pa %08x size %08x perm %03x\n",
- (uint32_t)pdir, (uint32_t)va, pa, size, perm);
-#endif
-
- while (addr <= last) {
- // get a pointer to the PTE for the current VA
- pte_t *pte = vm_getpte(pdir, addr, true);
- if (pte == NULL) {
- // couldn't find it
- return E_NO_PTE;
- }
-#if 0 && TRACING_VM
- cio_printf( " addr %08x pa %08x last %08x pte %08x *pte %08x\n",
- (uint32_t) addr, pa, (uint32_t) last, (uint32_t) pte, *pte
- );
-#endif
-
- // create the new entry for the page table
- pde_t newpte = pa | perm | PTE_P;
-
- // if this entry has already been mapped, we're in trouble
- if (IS_PRESENT(*pte)) {
- if (*pte != newpte) {
-#if TRACING_VM
- cio_printf(
- "vm_map: va %08x pa %08x pte %08x *pte %08x entry %08x\n",
- (uint32_t)va, pa, (uint32_t)pte, (uint32_t)*pte, newpte);
- cio_printf(" addr %08x PDIX 0x%x PTIX 0x%x\n", (uint32_t)addr,
- PDIX(addr), PTIX(addr));
-
- // dump the directory
- pmt_dump(pdir, true, PDIX(addr), 4);
-
- // find the relevant PDE entry
- uint32_t ix = PDIX(va);
- pde_t entry = pdir[ix];
- if (!IS_LARGE(entry)) {
- // round the PMT index down
- uint32_t ix2 = PTIX(va) & MOD4_MASK;
- // dump the PMT for the relevant directory entry
- pmt_dump((void *)P2V(PDE_ADDR(entry)), false, ix2, 4);
- }
-#endif
- PANIC(0, "mapping an already-mapped address");
- }
- }
-
- // ok, set the PTE as requested
- *pte = newpte;
-
- // nope - move to the next page
- addr += SZ_PAGE;
- pa += SZ_PAGE;
- }
- return SUCCESS;
-}
-
-/**
-** Name: vm_uvmdup
-**
-** Create a duplicate of the user portio of an existing page table
-** hierarchy. We assume that the "new" page directory exists and
-** the system portions of it should not be touched.
-**
-** Note: we do not duplicate the frames in the hierarchy - we just
-** create a duplicate of the hierarchy itself. This means that we
-** now have two sets of page tables that refer to the same physical
-** frames in memory.
-**
-** @param new New page directory
-** @param old Existing page directory
-**
-** @return status of the duplication attempt
-*/
-int vm_uvmdup(pde_t *new, pde_t *old)
-{
- if (old == NULL || new == NULL) {
- return E_BAD_PARAM;
- }
-
-#if TRACING_VM
- cio_printf("vmdup: old %08x new %08x\n", (uint32_t)old, (uint32_t)new);
-#endif
-
- // we only want to deal with the "user" half of the address space
- for (int i = 0; i < (N_PDE >> 1); ++i) {
- // the entry to copy
- pde_t entry = *old;
-
- // is this entry in use?
- if (IS_PRESENT(entry)) {
- // yes. if it points to a 4MB page, we just copy it;
- // otherwise, we must duplicate the next level PMT
-
- if (!IS_LARGE(entry)) {
- // it's a 4KB page, so we need to duplicate the PMT
- pte_t *newpt =
- (pte_t *)vm_pagedup((void *)P2V(PTE_ADDR(entry)));
- if (newpt == NULL) {
- return E_NO_MEMORY;
- }
-
- uint32_t perms = PERMS(entry);
-
- // create the new PDE entry by replacing the frame #
- entry = ((uint32_t)V2P(PTE_ADDR(newpt))) | perms;
- }
-
- } else {
- // not present, so create an empty entry
- entry = 0;
- }
-
- // send it on its way
- *new = entry;
-
- // move on down the line
- ++old;
- ++new;
- }
-
- return SUCCESS;
-}
-
-/**
-** Name: vm_print
-**
-** Print out a paging hierarchy.
-**
-** @param pt Page table to display
-** @param dir Is it a page directory (vs. a page table)?
-** @param mode How to display the entries
-*/
-void vm_print(void *pt, bool_t dir, enum vmmode_e mode)
-{
- cio_puts("\nVM hierarchy");
- if (pt == NULL) {
- cio_puts(" (NULL pointer)\n");
- return;
- }
-
- cio_printf(", starting at 0x%08x (%s):\n", (uint32_t)pt,
- dir ? "PDIR" : "PMT");
-
- ptdump(1, pt, dir, mode);
-}