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minix/servers/vm/arch/i386/pagetable.c
Tomas Hruby f6f20e1269 Overly restrictive assert 
- not true if APIC is enabled
2010-07-21 13:46:29 +00:00

1234 lines
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#define _SYSTEM 1
#define _POSIX_SOURCE 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/keymap.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/safecopies.h>
#include <minix/cpufeature.h>
#include <minix/bitmap.h>
#include <minix/debug.h>
#include <errno.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <env.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include "proto.h"
#include "glo.h"
#include "util.h"
#include "vm.h"
#include "sanitycheck.h"
#include "memory.h"
/* PDE used to map in kernel, kernel physical address. */
PRIVATE int id_map_high_pde = -1, pagedir_pde = -1;
PRIVATE u32_t global_bit = 0, pagedir_pde_val;
PRIVATE int proc_pde = 0;
/* 4MB page size available in hardware? */
PRIVATE int bigpage_ok = 0;
/* Our process table entry. */
struct vmproc *vmprocess = &vmproc[VM_PROC_NR];
/* Spare memory, ready to go after initialization, to avoid a
* circular dependency on allocating memory and writing it into VM's
* page table.
*/
#define SPAREPAGES 25
int missing_spares = SPAREPAGES;
PRIVATE struct {
void *page;
u32_t phys;
} sparepages[SPAREPAGES];
#define MAX_KERNMAPPINGS 10
PRIVATE struct {
phys_bytes phys_addr; /* Physical addr. */
phys_bytes len; /* Length in bytes. */
vir_bytes lin_addr; /* Offset in page table. */
int flags;
} kern_mappings[MAX_KERNMAPPINGS];
int kernmappings = 0;
/* Clicks must be pages, as
* - they must be page aligned to map them
* - they must be a multiple of the page size
* - it's inconvenient to have them bigger than pages, because we often want
* just one page
* May as well require them to be equal then.
*/
#if CLICK_SIZE != I386_PAGE_SIZE
#error CLICK_SIZE must be page size.
#endif
/* Bytes of virtual address space one pde controls. */
#define BYTESPERPDE (I386_VM_PT_ENTRIES * I386_PAGE_SIZE)
/* Nevertheless, introduce these macros to make the code readable. */
#define CLICK2PAGE(c) ((c) / CLICKSPERPAGE)
/* Page table that contains pointers to all page directories. */
u32_t page_directories_phys, *page_directories = NULL;
#define STATIC_SPAREPAGES 10
PRIVATE char static_sparepages[I386_PAGE_SIZE*STATIC_SPAREPAGES + I386_PAGE_SIZE];
#if SANITYCHECKS
/*===========================================================================*
* pt_sanitycheck *
*===========================================================================*/
PUBLIC void pt_sanitycheck(pt_t *pt, char *file, int line)
{
/* Basic pt sanity check. */
int i;
int slot;
MYASSERT(pt);
MYASSERT(pt->pt_dir);
MYASSERT(pt->pt_dir_phys);
for(slot = 0; slot < ELEMENTS(vmproc); slot++) {
if(pt == &vmproc[slot].vm_pt)
break;
}
if(slot >= ELEMENTS(vmproc)) {
panic("pt_sanitycheck: passed pt not in any proc");
}
MYASSERT(usedpages_add(pt->pt_dir_phys, I386_PAGE_SIZE) == OK);
for(i = proc_pde; i < I386_VM_DIR_ENTRIES; i++) {
if(pt->pt_pt[i]) {
int pte;
MYASSERT(vm_addrok(pt->pt_pt[i], 1));
if(!(pt->pt_dir[i] & I386_VM_PRESENT)) {
printf("slot %d: pt->pt_pt[%d] = %p, but pt_dir entry 0x%lx\n",
slot, i, pt->pt_pt[i], pt->pt_dir[i]);
}
MYASSERT(pt->pt_dir[i] & I386_VM_PRESENT);
MYASSERT(usedpages_add(I386_VM_PFA(pt->pt_dir[i]),
I386_PAGE_SIZE) == OK);
} else {
MYASSERT(!(pt->pt_dir[i] & I386_VM_PRESENT));
}
}
}
#endif
/*===========================================================================*
* findhole *
*===========================================================================*/
PRIVATE u32_t findhole(pt_t *pt, u32_t vmin, u32_t vmax)
{
/* Find a space in the virtual address space of pageteble 'pt',
* between page-aligned BYTE offsets vmin and vmax, to fit
* a page in. Return byte offset.
*/
u32_t freefound = 0, curv;
int pde = 0, try_restart;
static u32_t lastv = 0;
/* Input sanity check. */
assert(vmin + I386_PAGE_SIZE >= vmin);
assert(vmax >= vmin + I386_PAGE_SIZE);
assert((vmin % I386_PAGE_SIZE) == 0);
assert((vmax % I386_PAGE_SIZE) == 0);
#if SANITYCHECKS
curv = ((u32_t) random()) % ((vmax - vmin)/I386_PAGE_SIZE);
curv *= I386_PAGE_SIZE;
curv += vmin;
#else
curv = lastv;
if(curv < vmin || curv >= vmax)
curv = vmin;
#endif
try_restart = 1;
/* Start looking for a free page starting at vmin. */
while(curv < vmax) {
int pte;
assert(curv >= vmin);
assert(curv < vmax);
pde = I386_VM_PDE(curv);
pte = I386_VM_PTE(curv);
if(!(pt->pt_dir[pde] & I386_VM_PRESENT) ||
!(pt->pt_pt[pde][pte] & I386_VM_PRESENT)) {
lastv = curv;
return curv;
}
curv+=I386_PAGE_SIZE;
if(curv >= vmax && try_restart) {
curv = vmin;
try_restart = 0;
}
}
printf("VM: out of virtual address space in vm\n");
return NO_MEM;
}
/*===========================================================================*
* vm_freepages *
*===========================================================================*/
PRIVATE void vm_freepages(vir_bytes vir, vir_bytes phys, int pages, int reason)
{
assert(reason >= 0 && reason < VMP_CATEGORIES);
if(vir >= vmprocess->vm_stacktop) {
assert(!(vir % I386_PAGE_SIZE));
assert(!(phys % I386_PAGE_SIZE));
free_mem(ABS2CLICK(phys), pages);
if(pt_writemap(&vmprocess->vm_pt, arch_vir2map(vmprocess, vir),
MAP_NONE, pages*I386_PAGE_SIZE, 0, WMF_OVERWRITE) != OK)
panic("vm_freepages: pt_writemap failed");
} else {
printf("VM: vm_freepages not freeing VM heap pages (%d)\n",
pages);
}
#if SANITYCHECKS
/* If SANITYCHECKS are on, flush tlb so accessing freed pages is
* always trapped, also if not in tlb.
*/
if((sys_vmctl(SELF, VMCTL_FLUSHTLB, 0)) != OK) {
panic("VMCTL_FLUSHTLB failed");
}
#endif
}
/*===========================================================================*
* vm_getsparepage *
*===========================================================================*/
PRIVATE void *vm_getsparepage(u32_t *phys)
{
int s;
assert(missing_spares >= 0 && missing_spares <= SPAREPAGES);
for(s = 0; s < SPAREPAGES; s++) {
if(sparepages[s].page) {
void *sp;
sp = sparepages[s].page;
*phys = sparepages[s].phys;
sparepages[s].page = NULL;
missing_spares++;
assert(missing_spares >= 0 && missing_spares <= SPAREPAGES);
return sp;
}
}
return NULL;
}
/*===========================================================================*
* vm_checkspares *
*===========================================================================*/
PRIVATE void *vm_checkspares(void)
{
int s, n = 0;
static int total = 0, worst = 0;
assert(missing_spares >= 0 && missing_spares <= SPAREPAGES);
for(s = 0; s < SPAREPAGES && missing_spares > 0; s++)
if(!sparepages[s].page) {
n++;
if((sparepages[s].page = vm_allocpage(&sparepages[s].phys,
VMP_SPARE))) {
missing_spares--;
assert(missing_spares >= 0);
assert(missing_spares <= SPAREPAGES);
} else {
printf("VM: warning: couldn't get new spare page\n");
}
}
if(worst < n) worst = n;
total += n;
return NULL;
}
/*===========================================================================*
* vm_allocpage *
*===========================================================================*/
PUBLIC void *vm_allocpage(phys_bytes *phys, int reason)
{
/* Allocate a page for use by VM itself. */
phys_bytes newpage;
vir_bytes loc;
pt_t *pt;
int r;
static int level = 0;
void *ret;
pt = &vmprocess->vm_pt;
assert(reason >= 0 && reason < VMP_CATEGORIES);
level++;
assert(level >= 1);
assert(level <= 2);
if(level > 1 || !(vmprocess->vm_flags & VMF_HASPT) || !meminit_done) {
int r;
void *s;
s=vm_getsparepage(phys);
level--;
if(!s) {
util_stacktrace();
printf("VM: warning: out of spare pages\n");
}
return s;
}
/* VM does have a pagetable, so get a page and map it in there.
* Where in our virtual address space can we put it?
*/
loc = findhole(pt, arch_vir2map(vmprocess, vmprocess->vm_stacktop),
vmprocess->vm_arch.vm_data_top);
if(loc == NO_MEM) {
level--;
printf("VM: vm_allocpage: findhole failed\n");
return NULL;
}
/* Allocate page of memory for use by VM. As VM
* is trusted, we don't have to pre-clear it.
*/
if((newpage = alloc_mem(CLICKSPERPAGE, 0)) == NO_MEM) {
level--;
printf("VM: vm_allocpage: alloc_mem failed\n");
return NULL;
}
*phys = CLICK2ABS(newpage);
/* Map this page into our address space. */
if((r=pt_writemap(pt, loc, *phys, I386_PAGE_SIZE,
I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE, 0)) != OK) {
free_mem(newpage, CLICKSPERPAGE);
printf("vm_allocpage writemap failed\n");
level--;
return NULL;
}
if((r=sys_vmctl(SELF, VMCTL_FLUSHTLB, 0)) != OK) {
panic("VMCTL_FLUSHTLB failed: %d", r);
}
level--;
/* Return user-space-ready pointer to it. */
ret = (void *) arch_map2vir(vmprocess, loc);
return ret;
}
/*===========================================================================*
* vm_pagelock *
*===========================================================================*/
PUBLIC void vm_pagelock(void *vir, int lockflag)
{
/* Mark a page allocated by vm_allocpage() unwritable, i.e. only for VM. */
vir_bytes m;
int r;
u32_t flags = I386_VM_PRESENT | I386_VM_USER;
pt_t *pt;
pt = &vmprocess->vm_pt;
m = arch_vir2map(vmprocess, (vir_bytes) vir);
assert(!(m % I386_PAGE_SIZE));
if(!lockflag)
flags |= I386_VM_WRITE;
/* Update flags. */
if((r=pt_writemap(pt, m, 0, I386_PAGE_SIZE,
flags, WMF_OVERWRITE | WMF_WRITEFLAGSONLY)) != OK) {
panic("vm_lockpage: pt_writemap failed");
}
if((r=sys_vmctl(SELF, VMCTL_FLUSHTLB, 0)) != OK) {
panic("VMCTL_FLUSHTLB failed: %d", r);
}
return;
}
/*===========================================================================*
* vm_addrok *
*===========================================================================*/
PUBLIC int vm_addrok(void *vir, int writeflag)
{
/* Mark a page allocated by vm_allocpage() unwritable, i.e. only for VM. */
pt_t *pt = &vmprocess->vm_pt;
int pde, pte;
vir_bytes v = arch_vir2map(vmprocess, (vir_bytes) vir);
/* No PT yet? Don't bother looking. */
if(!(vmprocess->vm_flags & VMF_HASPT)) {
return 1;
}
pde = I386_VM_PDE(v);
pte = I386_VM_PTE(v);
if(!(pt->pt_dir[pde] & I386_VM_PRESENT)) {
printf("addr not ok: missing pde %d\n", pde);
return 0;
}
if(writeflag &&
!(pt->pt_dir[pde] & I386_VM_WRITE)) {
printf("addr not ok: pde %d present but pde unwritable\n", pde);
return 0;
}
if(!(pt->pt_pt[pde][pte] & I386_VM_PRESENT)) {
printf("addr not ok: missing pde %d / pte %d\n",
pde, pte);
return 0;
}
if(writeflag &&
!(pt->pt_pt[pde][pte] & I386_VM_WRITE)) {
printf("addr not ok: pde %d / pte %d present but unwritable\n",
pde, pte);
return 0;
}
return 1;
}
/*===========================================================================*
* pt_ptalloc *
*===========================================================================*/
PRIVATE int pt_ptalloc(pt_t *pt, int pde, u32_t flags)
{
/* Allocate a page table and write its address into the page directory. */
int i;
u32_t pt_phys;
/* Argument must make sense. */
assert(pde >= 0 && pde < I386_VM_DIR_ENTRIES);
assert(!(flags & ~(PTF_ALLFLAGS)));
/* We don't expect to overwrite page directory entry, nor
* storage for the page table.
*/
assert(!(pt->pt_dir[pde] & I386_VM_PRESENT));
assert(!pt->pt_pt[pde]);
/* Get storage for the page table. */
if(!(pt->pt_pt[pde] = vm_allocpage(&pt_phys, VMP_PAGETABLE)))
return ENOMEM;
for(i = 0; i < I386_VM_PT_ENTRIES; i++)
pt->pt_pt[pde][i] = 0; /* Empty entry. */
/* Make page directory entry.
* The PDE is always 'present,' 'writable,' and 'user accessible,'
* relying on the PTE for protection.
*/
pt->pt_dir[pde] = (pt_phys & I386_VM_ADDR_MASK) | flags
| I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE;
return OK;
}
/*===========================================================================*
* pt_ptalloc_in_range *
*===========================================================================*/
PUBLIC int pt_ptalloc_in_range(pt_t *pt, vir_bytes start, vir_bytes end,
u32_t flags, int verify)
{
/* Allocate all the page tables in the range specified. */
int pde, first_pde, last_pde;
first_pde = start ? I386_VM_PDE(start) : proc_pde;
last_pde = end ? I386_VM_PDE(end) : I386_VM_DIR_ENTRIES - 1;
assert(first_pde >= 0);
assert(last_pde < I386_VM_DIR_ENTRIES);
/* Scan all page-directory entries in the range. */
for(pde = first_pde; pde <= last_pde; pde++) {
assert(!(pt->pt_dir[pde] & I386_VM_BIGPAGE));
if(!(pt->pt_dir[pde] & I386_VM_PRESENT)) {
int r;
if(verify) {
printf("pt_ptalloc_in_range: no pde %d\n", pde);
return EFAULT;
}
assert(!pt->pt_dir[pde]);
if((r=pt_ptalloc(pt, pde, flags)) != OK) {
/* Couldn't do (complete) mapping.
* Don't bother freeing any previously
* allocated page tables, they're
* still writable, don't point to nonsense,
* and pt_ptalloc leaves the directory
* and other data in a consistent state.
*/
printf("pt_ptalloc_in_range: pt_ptalloc failed\n");
return r;
}
}
assert(pt->pt_dir[pde] & I386_VM_PRESENT);
}
return OK;
}
PRIVATE char *ptestr(u32_t pte)
{
#define FLAG(constant, name) { \
if(pte & (constant)) { strcat(str, name); strcat(str, " "); } \
}
static char str[30];
if(!(pte & I386_VM_PRESENT)) {
return "not present";
}
str[0] = '\0';
FLAG(I386_VM_WRITE, "W");
FLAG(I386_VM_USER, "U");
FLAG(I386_VM_PWT, "PWT");
FLAG(I386_VM_PCD, "PCD");
FLAG(I386_VM_ACC, "ACC");
FLAG(I386_VM_DIRTY, "DIRTY");
FLAG(I386_VM_PS, "PS");
FLAG(I386_VM_GLOBAL, "G");
FLAG(I386_VM_PTAVAIL1, "AV1");
FLAG(I386_VM_PTAVAIL2, "AV2");
FLAG(I386_VM_PTAVAIL3, "AV3");
return str;
}
/*===========================================================================*
* pt_map_in_range *
*===========================================================================*/
PUBLIC int pt_map_in_range(struct vmproc *src_vmp, struct vmproc *dst_vmp,
vir_bytes start, vir_bytes end)
{
/* Transfer all the mappings from the pt of the source process to the pt of
* the destination process in the range specified.
*/
int pde, pte;
int r;
vir_bytes viraddr, mapaddr;
pt_t *pt, *dst_pt;
pt = &src_vmp->vm_pt;
dst_pt = &dst_vmp->vm_pt;
end = end ? end : VM_DATATOP;
assert(start % I386_PAGE_SIZE == 0);
assert(end % I386_PAGE_SIZE == 0);
assert(I386_VM_PDE(start) >= proc_pde && start <= end);
assert(I386_VM_PDE(end) < I386_VM_DIR_ENTRIES);
#if LU_DEBUG
printf("VM: pt_map_in_range: src = %d, dst = %d\n",
src_vmp->vm_endpoint, dst_vmp->vm_endpoint);
printf("VM: pt_map_in_range: transferring from 0x%08x (pde %d pte %d) to 0x%08x (pde %d pte %d)\n",
start, I386_VM_PDE(start), I386_VM_PTE(start),
end, I386_VM_PDE(end), I386_VM_PTE(end));
#endif
/* Scan all page-table entries in the range. */
for(viraddr = start; viraddr <= end; viraddr += I386_PAGE_SIZE) {
pde = I386_VM_PDE(viraddr);
if(!(pt->pt_dir[pde] & I386_VM_PRESENT)) {
if(viraddr == VM_DATATOP) break;
continue;
}
pte = I386_VM_PTE(viraddr);
if(!(pt->pt_pt[pde][pte] & I386_VM_PRESENT)) {
if(viraddr == VM_DATATOP) break;
continue;
}
/* Transfer the mapping. */
dst_pt->pt_pt[pde][pte] = pt->pt_pt[pde][pte];
if(viraddr == VM_DATATOP) break;
}
return OK;
}
/*===========================================================================*
* pt_ptmap *
*===========================================================================*/
PUBLIC int pt_ptmap(struct vmproc *src_vmp, struct vmproc *dst_vmp)
{
/* Transfer mappings to page dir and page tables from source process and
* destination process. Make sure all the mappings are above the stack, not
* to corrupt valid mappings in the data segment of the destination process.
*/
int pde, r;
phys_bytes physaddr;
vir_bytes viraddr;
pt_t *pt;
assert(src_vmp->vm_stacktop == dst_vmp->vm_stacktop);
pt = &src_vmp->vm_pt;
#if LU_DEBUG
printf("VM: pt_ptmap: src = %d, dst = %d\n",
src_vmp->vm_endpoint, dst_vmp->vm_endpoint);
#endif
/* Transfer mapping to the page directory. */
assert((vir_bytes) pt->pt_dir >= src_vmp->vm_stacktop);
viraddr = arch_vir2map(src_vmp, (vir_bytes) pt->pt_dir);
physaddr = pt->pt_dir_phys & I386_VM_ADDR_MASK;
if((r=pt_writemap(&dst_vmp->vm_pt, viraddr, physaddr, I386_PAGE_SIZE,
I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE,
WMF_OVERWRITE)) != OK) {
return r;
}
#if LU_DEBUG
printf("VM: pt_ptmap: transferred mapping to page dir: 0x%08x (0x%08x)\n",
viraddr, physaddr);
#endif
/* Scan all non-reserved page-directory entries. */
for(pde=proc_pde; pde < I386_VM_DIR_ENTRIES; pde++) {
if(!(pt->pt_dir[pde] & I386_VM_PRESENT)) {
continue;
}
/* Transfer mapping to the page table. */
assert((vir_bytes) pt->pt_pt[pde] >= src_vmp->vm_stacktop);
viraddr = arch_vir2map(src_vmp, (vir_bytes) pt->pt_pt[pde]);
physaddr = pt->pt_dir[pde] & I386_VM_ADDR_MASK;
if((r=pt_writemap(&dst_vmp->vm_pt, viraddr, physaddr, I386_PAGE_SIZE,
I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE,
WMF_OVERWRITE)) != OK) {
return r;
}
}
#if LU_DEBUG
printf("VM: pt_ptmap: transferred mappings to page tables, pde range %d - %d\n",
proc_pde, I386_VM_DIR_ENTRIES - 1);
#endif
return OK;
}
/*===========================================================================*
* pt_writemap *
*===========================================================================*/
PUBLIC int pt_writemap(pt_t *pt, vir_bytes v, phys_bytes physaddr,
size_t bytes, u32_t flags, u32_t writemapflags)
{
/* Write mapping into page table. Allocate a new page table if necessary. */
/* Page directory and table entries for this virtual address. */
int p, r, pages;
int verify = 0;
if(writemapflags & WMF_VERIFY)
verify = 1;
assert(!(bytes % I386_PAGE_SIZE));
assert(!(flags & ~(PTF_ALLFLAGS)));
pages = bytes / I386_PAGE_SIZE;
/* MAP_NONE means to clear the mapping. It doesn't matter
* what's actually written into the PTE if I386_VM_PRESENT
* isn't on, so we can just write MAP_NONE into it.
*/
assert(physaddr == MAP_NONE || (flags & I386_VM_PRESENT));
assert(physaddr != MAP_NONE || !flags);
/* First make sure all the necessary page tables are allocated,
* before we start writing in any of them, because it's a pain
* to undo our work properly.
*/
r = pt_ptalloc_in_range(pt, v, v + I386_PAGE_SIZE*pages, flags, verify);
if(r != OK) {
return r;
}
/* Now write in them. */
for(p = 0; p < pages; p++) {
u32_t entry;
int pde = I386_VM_PDE(v);
int pte = I386_VM_PTE(v);
assert(!(v % I386_PAGE_SIZE));
assert(pte >= 0 && pte < I386_VM_PT_ENTRIES);
assert(pde >= 0 && pde < I386_VM_DIR_ENTRIES);
/* Page table has to be there. */
assert(pt->pt_dir[pde] & I386_VM_PRESENT);
/* Make sure page directory entry for this page table
* is marked present and page table entry is available.
*/
assert((pt->pt_dir[pde] & I386_VM_PRESENT));
assert(pt->pt_pt[pde]);
#if SANITYCHECKS
/* We don't expect to overwrite a page. */
if(!(writemapflags & (WMF_OVERWRITE|WMF_VERIFY)))
assert(!(pt->pt_pt[pde][pte] & I386_VM_PRESENT));
#endif
if(writemapflags & (WMF_WRITEFLAGSONLY|WMF_FREE)) {
physaddr = pt->pt_pt[pde][pte] & I386_VM_ADDR_MASK;
}
if(writemapflags & WMF_FREE) {
free_mem(ABS2CLICK(physaddr), 1);
}
/* Entry we will write. */
entry = (physaddr & I386_VM_ADDR_MASK) | flags;
if(verify) {
u32_t maskedentry;
maskedentry = pt->pt_pt[pde][pte];
maskedentry &= ~(I386_VM_ACC|I386_VM_DIRTY);
/* Verify pagetable entry. */
if(entry & I386_VM_WRITE) {
/* If we expect a writable page, allow a readonly page. */
maskedentry |= I386_VM_WRITE;
}
if(maskedentry != entry) {
printf("pt_writemap: mismatch: ");
if((entry & I386_VM_ADDR_MASK) !=
(maskedentry & I386_VM_ADDR_MASK)) {
printf("pt_writemap: physaddr mismatch (0x%lx, 0x%lx); ", entry, maskedentry);
} else printf("phys ok; ");
printf(" flags: found %s; ",
ptestr(pt->pt_pt[pde][pte]));
printf(" masked %s; ",
ptestr(maskedentry));
printf(" expected %s\n", ptestr(entry));
return EFAULT;
}
} else {
/* Write pagetable entry. */
#if SANITYCHECKS
assert(vm_addrok(pt->pt_pt[pde], 1));
#endif
pt->pt_pt[pde][pte] = entry;
}
physaddr += I386_PAGE_SIZE;
v += I386_PAGE_SIZE;
}
return OK;
}
/*===========================================================================*
* pt_checkrange *
*===========================================================================*/
PUBLIC int pt_checkrange(pt_t *pt, vir_bytes v, size_t bytes,
int write)
{
int p, pages, pde;
assert(!(bytes % I386_PAGE_SIZE));
pages = bytes / I386_PAGE_SIZE;
for(p = 0; p < pages; p++) {
u32_t entry;
int pde = I386_VM_PDE(v);
int pte = I386_VM_PTE(v);
assert(!(v % I386_PAGE_SIZE));
assert(pte >= 0 && pte < I386_VM_PT_ENTRIES);
assert(pde >= 0 && pde < I386_VM_DIR_ENTRIES);
/* Page table has to be there. */
if(!(pt->pt_dir[pde] & I386_VM_PRESENT))
return EFAULT;
/* Make sure page directory entry for this page table
* is marked present and page table entry is available.
*/
assert((pt->pt_dir[pde] & I386_VM_PRESENT) && pt->pt_pt[pde]);
if(!(pt->pt_pt[pde][pte] & I386_VM_PRESENT)) {
return EFAULT;
}
if(write && !(pt->pt_pt[pde][pte] & I386_VM_WRITE)) {
return EFAULT;
}
v += I386_PAGE_SIZE;
}
return OK;
}
/*===========================================================================*
* pt_new *
*===========================================================================*/
PUBLIC int pt_new(pt_t *pt)
{
/* Allocate a pagetable root. On i386, allocate a page-aligned page directory
* and set them to 0 (indicating no page tables are allocated). Lookup
* its physical address as we'll need that in the future. Verify it's
* page-aligned.
*/
int i;
/* Don't ever re-allocate/re-move a certain process slot's
* page directory once it's been created. This is a fraction
* faster, but also avoids having to invalidate the page
* mappings from in-kernel page tables pointing to
* the page directories (the page_directories data).
*/
if(!pt->pt_dir &&
!(pt->pt_dir = vm_allocpage(&pt->pt_dir_phys, VMP_PAGEDIR))) {
return ENOMEM;
}
for(i = 0; i < I386_VM_DIR_ENTRIES; i++) {
pt->pt_dir[i] = 0; /* invalid entry (I386_VM_PRESENT bit = 0) */
pt->pt_pt[i] = NULL;
}
/* Where to start looking for free virtual address space? */
pt->pt_virtop = 0;
/* Map in kernel. */
if(pt_mapkernel(pt) != OK)
panic("pt_new: pt_mapkernel failed");
return OK;
}
/*===========================================================================*
* pt_init *
*===========================================================================*/
PUBLIC void pt_init(phys_bytes usedlimit)
{
/* By default, the kernel gives us a data segment with pre-allocated
* memory that then can't grow. We want to be able to allocate memory
* dynamically, however. So here we copy the part of the page table
* that's ours, so we get a private page table. Then we increase the
* hardware segment size so we can allocate memory above our stack.
*/
pt_t *newpt;
int s, r;
vir_bytes v;
phys_bytes lo, hi;
vir_bytes extra_clicks;
u32_t moveup = 0;
int global_bit_ok = 0;
int free_pde;
int p;
struct vm_ep_data ep_data;
vir_bytes sparepages_mem;
phys_bytes sparepages_ph;
vir_bytes ptr;
/* Shorthand. */
newpt = &vmprocess->vm_pt;
/* Get ourselves spare pages. */
ptr = (vir_bytes) static_sparepages;
ptr += I386_PAGE_SIZE - (ptr % I386_PAGE_SIZE);
if(!(sparepages_mem = ptr))
panic("pt_init: aalloc for spare failed");
if((r=sys_umap(SELF, VM_D, (vir_bytes) sparepages_mem,
I386_PAGE_SIZE*SPAREPAGES, &sparepages_ph)) != OK)
panic("pt_init: sys_umap failed: %d", r);
missing_spares = 0;
assert(STATIC_SPAREPAGES < SPAREPAGES);
for(s = 0; s < SPAREPAGES; s++) {
if(s >= STATIC_SPAREPAGES) {
sparepages[s].page = NULL;
missing_spares++;
continue;
}
sparepages[s].page = (void *) (sparepages_mem + s*I386_PAGE_SIZE);
sparepages[s].phys = sparepages_ph + s*I386_PAGE_SIZE;
}
/* global bit and 4MB pages available? */
global_bit_ok = _cpufeature(_CPUF_I386_PGE);
bigpage_ok = _cpufeature(_CPUF_I386_PSE);
/* Set bit for PTE's and PDE's if available. */
if(global_bit_ok)
global_bit = I386_VM_GLOBAL;
/* The kernel and boot time processes need an identity mapping.
* We use full PDE's for this without separate page tables.
* Figure out which pde we can start using for other purposes.
*/
id_map_high_pde = usedlimit / I386_BIG_PAGE_SIZE;
/* We have to make mappings up till here. */
free_pde = id_map_high_pde+1;
/* Initial (current) range of our virtual address space. */
lo = CLICK2ABS(vmprocess->vm_arch.vm_seg[T].mem_phys);
hi = CLICK2ABS(vmprocess->vm_arch.vm_seg[S].mem_phys +
vmprocess->vm_arch.vm_seg[S].mem_len);
assert(!(lo % I386_PAGE_SIZE));
assert(!(hi % I386_PAGE_SIZE));
if(lo < VM_PROCSTART) {
moveup = VM_PROCSTART - lo;
assert(!(VM_PROCSTART % I386_PAGE_SIZE));
assert(!(lo % I386_PAGE_SIZE));
assert(!(moveup % I386_PAGE_SIZE));
}
/* Make new page table for ourselves, partly copied
* from the current one.
*/
if(pt_new(newpt) != OK)
panic("pt_init: pt_new failed");
/* Set up mappings for VM process. */
for(v = lo; v < hi; v += I386_PAGE_SIZE) {
phys_bytes addr;
u32_t flags;
/* We have to write the new position in the PT,
* so we can move our segments.
*/
if(pt_writemap(newpt, v+moveup, v, I386_PAGE_SIZE,
I386_VM_PRESENT|I386_VM_WRITE|I386_VM_USER, 0) != OK)
panic("pt_init: pt_writemap failed");
}
/* Move segments up too. */
vmprocess->vm_arch.vm_seg[T].mem_phys += ABS2CLICK(moveup);
vmprocess->vm_arch.vm_seg[D].mem_phys += ABS2CLICK(moveup);
vmprocess->vm_arch.vm_seg[S].mem_phys += ABS2CLICK(moveup);
/* Allocate us a page table in which to remember page directory
* pointers.
*/
if(!(page_directories = vm_allocpage(&page_directories_phys,
VMP_PAGETABLE)))
panic("no virt addr for vm mappings");
memset(page_directories, 0, I386_PAGE_SIZE);
/* Increase our hardware data segment to create virtual address
* space above our stack. We want to increase it to VM_DATATOP,
* like regular processes have.
*/
extra_clicks = ABS2CLICK(VM_DATATOP - hi);
vmprocess->vm_arch.vm_seg[S].mem_len += extra_clicks;
/* We pretend to the kernel we have a huge stack segment to
* increase our data segment.
*/
vmprocess->vm_arch.vm_data_top =
(vmprocess->vm_arch.vm_seg[S].mem_vir +
vmprocess->vm_arch.vm_seg[S].mem_len) << CLICK_SHIFT;
/* Where our free virtual address space starts.
* This is only a hint to the VM system.
*/
newpt->pt_virtop = 0;
/* Let other functions know VM now has a private page table. */
vmprocess->vm_flags |= VMF_HASPT;
/* Now reserve another pde for kernel's own mappings. */
{
int kernmap_pde;
phys_bytes addr, len;
int flags, index = 0;
u32_t offset = 0;
kernmap_pde = free_pde++;
offset = kernmap_pde * I386_BIG_PAGE_SIZE;
while(sys_vmctl_get_mapping(index, &addr, &len,
&flags) == OK) {
vir_bytes vir;
if(index >= MAX_KERNMAPPINGS)
panic("VM: too many kernel mappings: %d", index);
kern_mappings[index].phys_addr = addr;
kern_mappings[index].len = len;
kern_mappings[index].flags = flags;
kern_mappings[index].lin_addr = offset;
kern_mappings[index].flags =
I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE |
global_bit;
if(flags & VMMF_UNCACHED)
kern_mappings[index].flags |= PTF_NOCACHE;
if(addr % I386_PAGE_SIZE)
panic("VM: addr unaligned: %d", addr);
if(len % I386_PAGE_SIZE)
panic("VM: len unaligned: %d", len);
vir = arch_map2vir(&vmproc[VMP_SYSTEM], offset);
if(sys_vmctl_reply_mapping(index, vir) != OK)
panic("VM: reply failed");
offset += len;
index++;
kernmappings++;
}
}
/* Find a PDE below processes available for mapping in the
* page directories (readonly).
*/
pagedir_pde = free_pde++;
pagedir_pde_val = (page_directories_phys & I386_VM_ADDR_MASK) |
I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE;
/* Tell kernel about free pde's. */
while(free_pde*I386_BIG_PAGE_SIZE < VM_PROCSTART) {
if((r=sys_vmctl(SELF, VMCTL_I386_FREEPDE, free_pde++)) != OK) {
panic("VMCTL_I386_FREEPDE failed: %d", r);
}
}
/* first pde in use by process. */
proc_pde = free_pde;
/* Give our process the new, copied, private page table. */
pt_mapkernel(newpt); /* didn't know about vm_dir pages earlier */
pt_bind(newpt, vmprocess);
/* new segment limit for the kernel after paging is enabled */
ep_data.data_seg_limit = free_pde*I386_BIG_PAGE_SIZE;
/* the memory map which must be installed after paging is enabled */
ep_data.mem_map = vmprocess->vm_arch.vm_seg;
/* Now actually enable paging. */
if(sys_vmctl_enable_paging(&ep_data) != OK)
panic("pt_init: enable paging failed");
/* Back to reality - this is where the stack actually is. */
vmprocess->vm_arch.vm_seg[S].mem_len -= extra_clicks;
/* Pretend VM stack top is the same as any regular process, not to
* have discrepancies with new VM instances later on.
*/
vmprocess->vm_stacktop = VM_STACKTOP;
/* All OK. */
return;
}
/*===========================================================================*
* pt_init_mem *
*===========================================================================*/
PUBLIC void pt_init_mem()
{
/* Architecture-specific memory initialization. Make sure all the pages
* shared with the kernel and VM's page tables are mapped above the stack,
* so that we can easily transfer existing mappings for new VM instances.
*/
u32_t new_page_directories_phys, *new_page_directories;
u32_t new_pt_dir_phys, *new_pt_dir;
u32_t new_pt_phys, *new_pt;
pt_t *vmpt;
int i;
vmpt = &vmprocess->vm_pt;
/* We should be running this when VM has been assigned a page
* table and memory initialization has already been performed.
*/
assert(vmprocess->vm_flags & VMF_HASPT);
assert(meminit_done);
/* Throw away static spare pages. */
vm_checkspares();
for(i = 0; i < SPAREPAGES; i++) {
if(sparepages[i].page && (vir_bytes) sparepages[i].page
< vmprocess->vm_stacktop) {
sparepages[i].page = NULL;
missing_spares++;
}
}
vm_checkspares();
/* Rellocate page for page directories pointers. */
if(!(new_page_directories = vm_allocpage(&new_page_directories_phys,
VMP_PAGETABLE)))
panic("unable to reallocated page for page dir ptrs");
assert((vir_bytes) new_page_directories >= vmprocess->vm_stacktop);
memcpy(new_page_directories, page_directories, I386_PAGE_SIZE);
page_directories = new_page_directories;
pagedir_pde_val = (new_page_directories_phys & I386_VM_ADDR_MASK) |
(pagedir_pde_val & ~I386_VM_ADDR_MASK);
/* Remap in kernel. */
pt_mapkernel(vmpt);
/* Reallocate VM's page directory. */
if((vir_bytes) vmpt->pt_dir < vmprocess->vm_stacktop) {
if(!(new_pt_dir= vm_allocpage(&new_pt_dir_phys, VMP_PAGEDIR))) {
panic("unable to reallocate VM's page directory");
}
assert((vir_bytes) new_pt_dir >= vmprocess->vm_stacktop);
memcpy(new_pt_dir, vmpt->pt_dir, I386_PAGE_SIZE);
vmpt->pt_dir = new_pt_dir;
vmpt->pt_dir_phys = new_pt_dir_phys;
pt_bind(vmpt, vmprocess);
}
/* Reallocate VM's page tables. */
for(i = proc_pde; i < I386_VM_DIR_ENTRIES; i++) {
if(!(vmpt->pt_dir[i] & I386_VM_PRESENT)) {
continue;
}
assert(vmpt->pt_pt[i]);
if((vir_bytes) vmpt->pt_pt[i] >= vmprocess->vm_stacktop) {
continue;
}
vm_checkspares();
if(!(new_pt = vm_allocpage(&new_pt_phys, VMP_PAGETABLE)))
panic("unable to reallocate VM's page table");
assert((vir_bytes) new_pt >= vmprocess->vm_stacktop);
memcpy(new_pt, vmpt->pt_pt[i], I386_PAGE_SIZE);
vmpt->pt_pt[i] = new_pt;
vmpt->pt_dir[i] = (new_pt_phys & I386_VM_ADDR_MASK) |
(vmpt->pt_dir[i] & ~I386_VM_ADDR_MASK);
}
}
/*===========================================================================*
* pt_bind *
*===========================================================================*/
PUBLIC int pt_bind(pt_t *pt, struct vmproc *who)
{
int slot, ispt;
u32_t phys;
void *pdes;
/* Basic sanity checks. */
assert(who);
assert(who->vm_flags & VMF_INUSE);
assert(pt);
assert(pagedir_pde >= 0);
slot = who->vm_slot;
assert(slot >= 0);
assert(slot < ELEMENTS(vmproc));
assert(slot < I386_VM_PT_ENTRIES);
phys = pt->pt_dir_phys & I386_VM_ADDR_MASK;
assert(pt->pt_dir_phys == phys);
/* Update "page directory pagetable." */
page_directories[slot] = phys | I386_VM_PRESENT|I386_VM_WRITE;
/* This is where the PDE's will be visible to the kernel
* in its address space.
*/
pdes = (void *) arch_map2vir(&vmproc[VMP_SYSTEM],
pagedir_pde*I386_BIG_PAGE_SIZE +
slot * I386_PAGE_SIZE);
#if 0
printf("VM: slot %d endpoint %d has pde val 0x%lx at kernel address 0x%lx\n",
slot, who->vm_endpoint, page_directories[slot], pdes);
#endif
/* Tell kernel about new page table root. */
return sys_vmctl_set_addrspace(who->vm_endpoint,
pt ? pt->pt_dir_phys : 0,
pt ? pdes : 0);
}
/*===========================================================================*
* pt_free *
*===========================================================================*/
PUBLIC void pt_free(pt_t *pt)
{
/* Free memory associated with this pagetable. */
int i;
for(i = 0; i < I386_VM_DIR_ENTRIES; i++)
if(pt->pt_pt[i])
vm_freepages((vir_bytes) pt->pt_pt[i],
I386_VM_PFA(pt->pt_dir[i]), 1, VMP_PAGETABLE);
return;
}
/*===========================================================================*
* pt_mapkernel *
*===========================================================================*/
PUBLIC int pt_mapkernel(pt_t *pt)
{
int r, i;
/* Any i386 page table needs to map in the kernel address space. */
assert(vmproc[VMP_SYSTEM].vm_flags & VMF_INUSE);
if(bigpage_ok) {
int pde;
for(pde = 0; pde <= id_map_high_pde; pde++) {
phys_bytes addr;
addr = pde * I386_BIG_PAGE_SIZE;
assert((addr & I386_VM_ADDR_MASK) == addr);
pt->pt_dir[pde] = addr | I386_VM_PRESENT |
I386_VM_BIGPAGE | I386_VM_USER |
I386_VM_WRITE | global_bit;
}
} else {
panic("VM: pt_mapkernel: no bigpage");
}
if(pagedir_pde >= 0) {
/* Kernel also wants to know about all page directories. */
pt->pt_dir[pagedir_pde] = pagedir_pde_val;
}
for(i = 0; i < kernmappings; i++) {
if(pt_writemap(pt,
kern_mappings[i].lin_addr,
kern_mappings[i].phys_addr,
kern_mappings[i].len,
kern_mappings[i].flags, 0) != OK) {
panic("pt_mapkernel: pt_writemap failed");
}
}
return OK;
}
/*===========================================================================*
* pt_cycle *
*===========================================================================*/
PUBLIC void pt_cycle(void)
{
vm_checkspares();
}
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