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minix/servers/vm/arch/i386/pagetable.c
Ben Gras 6d7b770761 VM: static data structure for mem allocation 
. allocate physical memory using a fixed, pre-allocated bitmap so there
   are no call cycles and it's avilable earlier
2012-09-18 13:17:48 +02:00

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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. */
static int pagedir_pde = -1;
static u32_t global_bit = 0, pagedir_pde_val;
static multiboot_module_t *kern_mb_mod = NULL;
static size_t kern_size = 0;
static int kern_start_pde = -1;
/* 4MB page size available in hardware? */
static 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.
*/
#if SANITYCHECKS
#define SPAREPAGES 100
#define STATIC_SPAREPAGES 90
#else
#define SPAREPAGES 15
#define STATIC_SPAREPAGES 10
#endif
int missing_spares = SPAREPAGES;
static struct {
void *page;
phys_bytes phys;
} sparepages[SPAREPAGES];
#define MAX_KERNMAPPINGS 10
static struct {
phys_bytes phys_addr; /* Physical addr. */
phys_bytes len; /* Length in bytes. */
vir_bytes vir_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
/* Page table that contains pointers to all page directories. */
phys_bytes page_directories_phys;
u32_t *page_directories = NULL;
static char static_sparepages[I386_PAGE_SIZE*STATIC_SPAREPAGES]
__aligned(I386_PAGE_SIZE);
#if SANITYCHECKS
/*===========================================================================*
* pt_sanitycheck *
*===========================================================================*/
void pt_sanitycheck(pt_t *pt, char *file, int line)
{
/* Basic pt sanity check. */
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);
}
#endif
/*===========================================================================*
* findhole *
*===========================================================================*/
static u32_t findhole(void)
{
/* Find a space in the virtual address space of VM. */
u32_t curv;
int pde = 0, try_restart;
static u32_t lastv = 0;
pt_t *pt = &vmprocess->vm_pt;
extern char _end;
vir_bytes vmin, vmax;
vmin = (vir_bytes) (&_end) & I386_VM_ADDR_MASK; /* marks end of VM BSS */
vmax = VM_STACKTOP;
/* 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 *
*===========================================================================*/
static void vm_freepages(vir_bytes vir, vir_bytes phys, int pages, int reason)
{
assert(reason >= 0 && reason < VMP_CATEGORIES);
assert(!(vir % I386_PAGE_SIZE));
assert(!(phys % I386_PAGE_SIZE));
extern char _end;
if(vir < (vir_bytes) &_end) {
printf("VM: not freeing static page\n");
return;
}
free_mem(ABS2CLICK(phys), pages);
if(pt_writemap(vmprocess, &vmprocess->vm_pt, vir,
MAP_NONE, pages*I386_PAGE_SIZE, 0, WMF_OVERWRITE) != OK)
panic("vm_freepages: pt_writemap failed");
#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 *
*===========================================================================*/
static void *vm_getsparepage(phys_bytes *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 *
*===========================================================================*/
static 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;
}
static int pt_init_done;
/*===========================================================================*
* vm_allocpage *
*===========================================================================*/
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) || !pt_init_done) {
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();
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(vmprocess, 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 *) loc;
return ret;
}
/*===========================================================================*
* vm_pagelock *
*===========================================================================*/
void vm_pagelock(void *vir, int lockflag)
{
/* Mark a page allocated by vm_allocpage() unwritable, i.e. only for VM. */
vir_bytes m = (vir_bytes) vir;
int r;
u32_t flags = I386_VM_PRESENT | I386_VM_USER;
pt_t *pt;
pt = &vmprocess->vm_pt;
assert(!(m % I386_PAGE_SIZE));
if(!lockflag)
flags |= I386_VM_WRITE;
/* Update flags. */
if((r=pt_writemap(vmprocess, 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 *
*===========================================================================*/
int vm_addrok(void *vir, int writeflag)
{
pt_t *pt = &vmprocess->vm_pt;
int pde, pte;
vir_bytes v = (vir_bytes) vir;
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 *
*===========================================================================*/
static 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;
phys_bytes 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 *
*===========================================================================*/
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 = I386_VM_PDE(start);
last_pde = I386_VM_PDE(end-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]);
assert(pt->pt_dir[pde] & I386_VM_PRESENT);
}
return OK;
}
static 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 *
*===========================================================================*/
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;
vir_bytes viraddr;
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(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 *
*===========================================================================*/
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;
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. */
viraddr = (vir_bytes) pt->pt_dir;
physaddr = pt->pt_dir_phys & I386_VM_ADDR_MASK;
if((r=pt_writemap(dst_vmp, &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=0; pde < I386_VM_DIR_ENTRIES; pde++) {
if(!(pt->pt_dir[pde] & I386_VM_PRESENT)) {
continue;
}
/* Transfer mapping to the page table. */
viraddr = (vir_bytes) pt->pt_pt[pde];
physaddr = pt->pt_dir[pde] & I386_VM_ADDR_MASK;
if((r=pt_writemap(dst_vmp, &dst_vmp->vm_pt, viraddr, physaddr, I386_PAGE_SIZE,
I386_VM_PRESENT | I386_VM_USER | I386_VM_WRITE,
WMF_OVERWRITE)) != OK) {
return r;
}
}
return OK;
}
void pt_clearmapcache(void)
{
/* Make sure kernel will invalidate tlb when using current
* pagetable (i.e. vm's) to make new mappings before new cr3
* is loaded.
*/
if(sys_vmctl(SELF, VMCTL_CLEARMAPCACHE, 0) != OK)
panic("VMCTL_CLEARMAPCACHE failed");
}
/*===========================================================================*
* pt_writemap *
*===========================================================================*/
int pt_writemap(struct vmproc * vmp,
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, pages;
int verify = 0;
int ret = OK;
#ifdef CONFIG_SMP
int vminhibit_clear = 0;
/* FIXME
* don't do it everytime, stop the process only on the first change and
* resume the execution on the last change. Do in a wrapper of this
* function
*/
if (vmp && vmp->vm_endpoint != NONE && vmp->vm_endpoint != VM_PROC_NR &&
!(vmp->vm_flags & VMF_EXITING)) {
sys_vmctl(vmp->vm_endpoint, VMCTL_VMINHIBIT_SET, 0);
vminhibit_clear = 1;
}
#endif
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.
*/
ret = pt_ptalloc_in_range(pt, v, v + I386_PAGE_SIZE*pages, flags, verify);
if(ret != OK) {
printf("VM: writemap: pt_ptalloc_in_range failed\n");
goto resume_exit;
}
/* 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);
if(!v) { printf("VM: warning: making zero page for %d\n",
vmp->vm_endpoint); }
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);
/* We do not expect it to be a bigpage. */
assert(!(pt->pt_dir[pde] & I386_VM_BIGPAGE));
/* Make sure page directory entry for this page table
* is marked present and page table entry is available.
*/
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); ",
(long)entry, (long)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));
ret = EFAULT;
goto resume_exit;
}
} else {
/* Write pagetable entry. */
pt->pt_pt[pde][pte] = entry;
}
physaddr += I386_PAGE_SIZE;
v += I386_PAGE_SIZE;
}
resume_exit:
#ifdef CONFIG_SMP
if (vminhibit_clear) {
assert(vmp && vmp->vm_endpoint != NONE && vmp->vm_endpoint != VM_PROC_NR &&
!(vmp->vm_flags & VMF_EXITING));
sys_vmctl(vmp->vm_endpoint, VMCTL_VMINHIBIT_CLEAR, 0);
}
#endif
return ret;
}
/*===========================================================================*
* pt_checkrange *
*===========================================================================*/
int pt_checkrange(pt_t *pt, vir_bytes v, size_t bytes,
int write)
{
int p, pages;
assert(!(bytes % I386_PAGE_SIZE));
pages = bytes / I386_PAGE_SIZE;
for(p = 0; p < pages; p++) {
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 *
*===========================================================================*/
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((phys_bytes *)&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;
}
static int freepde(void)
{
int p = kernel_boot_info.freepde_start++;
assert(kernel_boot_info.freepde_start < I386_VM_DIR_ENTRIES);
return p;
}
/*===========================================================================*
* pt_init *
*===========================================================================*/
void pt_init(void)
{
pt_t *newpt;
int s, r, p;
int global_bit_ok = 0;
vir_bytes sparepages_mem;
static u32_t currentpagedir[I386_VM_DIR_ENTRIES];
int m = kernel_boot_info.kern_mod;
u32_t mypdbr; /* Page Directory Base Register (cr3) value */
/* Find what the physical location of the kernel is. */
assert(m >= 0);
assert(m < kernel_boot_info.mods_with_kernel);
assert(kernel_boot_info.mods_with_kernel < MULTIBOOT_MAX_MODS);
kern_mb_mod = &kernel_boot_info.module_list[m];
kern_size = kern_mb_mod->mod_end - kern_mb_mod->mod_start;
assert(!(kern_mb_mod->mod_start % I386_BIG_PAGE_SIZE));
assert(!(kernel_boot_info.vir_kern_start % I386_BIG_PAGE_SIZE));
kern_start_pde = kernel_boot_info.vir_kern_start / I386_BIG_PAGE_SIZE;
/* Get ourselves spare pages. */
sparepages_mem = (vir_bytes) static_sparepages;
assert(!(sparepages_mem % I386_PAGE_SIZE));
/* Spare pages are used to allocate memory before VM has its own page
* table that things (i.e. arbitrary physical memory) can be mapped into.
* We get it by pre-allocating it in our bss (allocated and mapped in by
* the kernel) in static_sparepages. We also need the physical addresses
* though; we look them up now so they are ready for use.
*/
missing_spares = 0;
assert(STATIC_SPAREPAGES < SPAREPAGES);
for(s = 0; s < SPAREPAGES; s++) {
vir_bytes v = (sparepages_mem + s*I386_PAGE_SIZE);;
phys_bytes ph;
if((r=sys_umap(SELF, VM_D, (vir_bytes) v,
I386_PAGE_SIZE*SPAREPAGES, &ph)) != OK)
panic("pt_init: sys_umap failed: %d", r);
if(s >= STATIC_SPAREPAGES) {
sparepages[s].page = NULL;
missing_spares++;
continue;
}
sparepages[s].page = (void *) v;
sparepages[s].phys = ph;
}
/* 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;
/* 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);
/* 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 = freepde();
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].vir_addr = offset;
kern_mappings[index].flags =
I386_VM_PRESENT;
if(flags & VMMF_UNCACHED)
kern_mappings[index].flags |= PTF_NOCACHE;
if(flags & VMMF_USER)
kern_mappings[index].flags |= I386_VM_USER;
if(flags & VMMF_WRITE)
kern_mappings[index].flags |= I386_VM_WRITE;
if(flags & VMMF_GLO)
kern_mappings[index].flags |= I386_VM_GLOBAL;
if(addr % I386_PAGE_SIZE)
panic("VM: addr unaligned: %d", addr);
if(len % I386_PAGE_SIZE)
panic("VM: len unaligned: %d", len);
vir = 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.
*/
pagedir_pde = freepde();
pagedir_pde_val = (page_directories_phys & I386_VM_ADDR_MASK) |
I386_VM_PRESENT | I386_VM_WRITE;
/* Allright. Now. We have to make our own page directory and page tables,
* that the kernel has already set up, accessible to us. It's easier to
* understand if we just copy all the required pages (i.e. page directory
* and page tables), and set up the pointers as if VM had done it itself.
*
* This allocation will happen without using any page table, and just
* uses spare pages.
*/
newpt = &vmprocess->vm_pt;
if(pt_new(newpt) != OK)
panic("vm pt_new failed");
/* Get our current pagedir so we can see it. */
if(sys_vmctl_get_pdbr(SELF, &mypdbr) != OK)
panic("VM: sys_vmctl_get_pdbr failed");
if(sys_vircopy(NONE, mypdbr, SELF,
(vir_bytes) currentpagedir, I386_PAGE_SIZE) != OK)
panic("VM: sys_vircopy failed");
/* We have mapped in kernel ourselves; now copy mappings for VM
* that kernel made, including allocations for BSS. Skip identity
* mapping bits; just map in VM.
*/
for(p = 0; p < I386_VM_DIR_ENTRIES; p++) {
u32_t entry = currentpagedir[p];
phys_bytes ptaddr_kern, ptaddr_us;
/* BIGPAGEs are kernel mapping (do ourselves) or boot
* identity mapping (don't want).
*/
if(!(entry & I386_VM_PRESENT)) continue;
if((entry & I386_VM_BIGPAGE)) continue;
if(pt_ptalloc(newpt, p, 0) != OK)
panic("pt_ptalloc failed");
assert(newpt->pt_dir[p] & I386_VM_PRESENT);
ptaddr_kern = entry & I386_VM_ADDR_MASK;
ptaddr_us = newpt->pt_dir[p] & I386_VM_ADDR_MASK;
/* Copy kernel-initialized pagetable contents into our
* normally accessible pagetable.
*/
if(sys_abscopy(ptaddr_kern, ptaddr_us, I386_PAGE_SIZE) != OK)
panic("pt_init: abscopy failed");
}
/* Inform kernel vm has a newly built page table. */
assert(vmproc[VM_PROC_NR].vm_endpoint == VM_PROC_NR);
pt_bind(newpt, &vmproc[VM_PROC_NR]);
pt_init_done = 1;
/* All OK. */
return;
}
/*===========================================================================*
* pt_bind *
*===========================================================================*/
int pt_bind(pt_t *pt, struct vmproc *who)
{
int slot;
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 *) (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_dir_phys, pdes);
}
/*===========================================================================*
* pt_free *
*===========================================================================*/
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 *
*===========================================================================*/
int pt_mapkernel(pt_t *pt)
{
int i;
int kern_pde = kern_start_pde;
phys_bytes addr, mapped = 0;
/* Any i386 page table needs to map in the kernel address space. */
assert(bigpage_ok);
assert(pagedir_pde >= 0);
assert(kern_pde >= 0);
/* pt_init() has made sure this is ok. */
addr = kern_mb_mod->mod_start;
/* Actually mapping in kernel */
while(mapped < kern_size) {
pt->pt_dir[kern_pde] = addr | I386_VM_PRESENT |
I386_VM_BIGPAGE | I386_VM_WRITE | global_bit;
kern_pde++;
mapped += I386_BIG_PAGE_SIZE;
addr += I386_BIG_PAGE_SIZE;
}
/* Kernel also wants to know about all page directories. */
assert(pagedir_pde > kern_pde);
pt->pt_dir[pagedir_pde] = pagedir_pde_val;
/* Kernel also wants various mappings of its own. */
for(i = 0; i < kernmappings; i++) {
if(pt_writemap(NULL, pt,
kern_mappings[i].vir_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 *
*===========================================================================*/
void pt_cycle(void)
{
vm_checkspares();
}
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