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Diffstat (limited to '')
| -rw-r--r-- | kernel/old/vm.c | 625 |
1 files changed, 0 insertions, 625 deletions
diff --git a/kernel/old/vm.c b/kernel/old/vm.c deleted file mode 100644 index 749bed3..0000000 --- a/kernel/old/vm.c +++ /dev/null @@ -1,625 +0,0 @@ -/** -** @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: uva2kva -** -** Convert a user VA into a kernel address. Works for all addresses - -** if the address is a page address, the PERMS(va) value will be 0; -** otherwise, it is the offset into the page. -** -** @param pdir Pointer to the page directory to examine -** @param va Virtual address to check -*/ -ATTR_UNUSED -static void *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); -} - - -/* -** 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 ); - - // switch to it - vm_set_kvm(); - - // install the page fault handler - install_isr( VEC_PAGE_FAULT, vm_isr ); -} - -/** -** 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 dst Pointer to where the duplicate should go -** @param curr Pointer to the entry to be duplicated -** -** @return true on success, else false -*/ -bool_t vm_pdedup( pde_t *dst, pde_t *curr ) { - - assert1( curr != NULL ); - assert1( dst != NULL ); - -#if TRACING_VM - cio_printf( "vm_pdedup dst %08x curr %08x\n", - (uint32_t) dst, (uint32_t) curr ); -#endif - pde_t entry = *curr; - - // simplest case - if( !IS_PRESENT(entry) ) { - *dst = 0; - return true; - } - - // OK, we have an entry; allocate a page table for it - pte_t *newtbl = (pte_t *) km_page_alloc(); - if( newtbl == NULL ) { - return false; - } - - // we could clear the new table, but we'll be assigning to - // each entry anyway, so we'll save the execution time - - // address of the page table for this directory entry - pte_t *old = (pte_t *) PDE_ADDR(entry); - - // pointer to the first PTE in the new table - pte_t *new = newtbl; - - for( int i = 0 ; i < N_PTE; ++i ) { - if( !IS_PRESENT(*old) ) { - *new = 0; - } else { - *new = *old; - } - ++old; - ++new; - } - - // replace the page table address - // upper 22 bits from 'newtbl', lower 12 from '*curr' - *dst = (pde_t) ( PTE_ADDR(newtbl) | PERMS(entry) ); - - return true; -} - -/** -** 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 *ptab; - - // sanity check - assert1( pdir != NULL ); - - // get the PDIR entry for this virtual address - pde_t *pde = &pdir[ PDIX(va) ]; - - // is it already set up? - if( IS_PRESENT(*pde) ) { - - // yes! - ptab = (pte_t*)P2V(PTE_ADDR(*pde)); - - } else { - - // no - should we create it? - if( !alloc ) { - // nope, so just return - return NULL; - } - - // yes - try to allocate a page table - ptab = (pte_t *) km_page_alloc(); - if( ptab == NULL ) { - WARNING( "can't allocate page table" ); - return NULL; - } - - // who knows what was left in this page.... - memclr( ptab, 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 - *pde = ((uint32_t) V2P(ptab)) | PDE_P | PDE_RW; - } - - // finally, return a pointer to the entry in the - // page table for this VA - return &ptab[ 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; - } - - // 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_end - k->pa_start, - k->pa_start, k->perm ); - if( stat != SUCCESS ) { - vm_free( pdir ); - return 0; - } - } - - 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 kernel page directory - pde_t *curr = kpdir; - pde_t *dst = new; - for( int i = 0; i < N_PDE; ++i ) { - - if( *curr != 0 ) { - // found an active one - duplicate it - if( !vm_pdedup(dst,curr) ) { - return NULL; - } - } - - ++curr; - ++dst; - } - - return new; - -} - -/** -** Name: vm_set_kvm -** -** Switch the page table register to the kernel's page directory. -*/ -void vm_set_kvm( void ) { - w_cr3( V2P(kpdir) ); // switch to the kernel page table -} - -/** -** 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 ) { - assert( p != NULL ); - assert( p->pdir != NULL ); - - w_cr3( V2P(p->pdir) ); // switch to process's address space -} - -/** -** 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? - uint_t npages = ((size & MOD4K_BITS) ? PGUP(size) : size) >> MOD4K_SHIFT; - - // permission set for the PTEs - uint_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 (%u, %u pgs)\n", - (uint32_t) pdir, wr ? "W" : "!W", (uint32_t) va, size ); - 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 ) { - // TODO 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 ) { - // TODO 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) (PTE_ADDR(page) | entrybase); - *pte = entry; - - // copy data if we need to - if( data != NULL && bytes > 0 ) { - // how much to copy - uint_t num = bytes > SZ_PAGE ? SZ_PAGE : bytes; - // do it! - memcpy( (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 ) { - - // 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; - 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 *) PTE_ADDR(entry); - - // walk the PMT - for( int j = 0; j < N_PTE; ++j ) { - // does this entry point to a frame? - if( IS_PRESENT(*pmt) ) { - // yes - free the frame - km_page_free( (void *) PTE_ADDR(*pmt) ); - // mark it so we don't get surprised - *pmt = 0; - } - // move on - ++pmt; - } - // now, free the PMT itself - km_page_free( (void *) PDE_ADDR(entry) ); - *curr = 0; - } - - // move to the next entry - ++curr; - } - - // finally, free the PDIR itself - km_page_free( (void *) pdir ); -} - -/* -** 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 size Length of the range to be mapped -** @param pa The starting physical address -** @param perm Permission bits for the PTEs -** -** @return the status of the mapping attempt -*/ -int vm_map( pde_t *pdir, void *va, uint_t size, uint_t pa, int perm ) { - - // round the VA down to its page boundary - char *addr = (char*)PGDOWN((uint_t)va); - - // round the end of the range down to its page boundary - char *last = (char*)PGDOWN(((uint_t)va) + size - 1); - - 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 this entry has already been mapped, we're in trouble - if( IS_PRESENT(*pte) ) { - cio_printf( "vm_map(%08x,%08x,%u,%08x,%03x)\n", - (uint32_t) pdir, (uint32_t) va, size, pa, perm ); - cio_printf( " addr %08x last %08x pte %08x *pte %08x\n", - (uint32_t) addr, (uint32_t) last, - (uint32_t) pte, *pte ); - - PANIC( 0, "mapping an already-mapped address" ); - } - - // ok, set the PTE as requested - *pte = pa | perm | PTE_P; - - // 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 old Existing page directory -** @param new New page directory -** -** @return status of the duplication attempt -*/ -int vm_uvmdup( pde_t *old, pde_t *new ) { - - if( old == NULL || new == NULL ) { - return E_BAD_PARAM; - } - - // 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 *)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) 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; -} |