oops, vm.c
This commit is contained in:
Frans Kaashoek
parent
4714c20521
commit
b364c4b881
353
vm.c
Normal file
353
vm.c
Normal file
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@ -0,0 +1,353 @@
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#include "param.h"
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#include "types.h"
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#include "defs.h"
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#include "x86.h"
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#include "mmu.h"
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#include "proc.h"
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#include "elf.h"
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static uint kerntext; // linear/physical address of start of kernel text
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static uint kerntsz;
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static uint kerndata;
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static uint kerndsz;
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static uint kernend;
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static uint freesz;
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static pde_t *kpgdir;
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void
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printstack()
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{
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uint *ebp = (uint *) rebp();
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uint i;
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cprintf("kernel stack: 0x%x\n", ebp);
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while (ebp) {
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if (ebp < (uint *) kerntext) // don't follow user ebp
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return;
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cprintf(" ebp %x saved ebp %x eip %x args", ebp, ebp[0], ebp[1]);
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for (i = 0; i < 4; i++)
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cprintf(" %x", ebp[2+i]);
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cprintf("\n");
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ebp = (uint *) ebp[0];
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}
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}
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void
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printpgdir(pde_t *pgdir)
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{
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uint i;
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uint j;
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cprintf("printpgdir 0x%x\n", pgdir);
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for (i = 0; i < NPDENTRIES; i++) {
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if (pgdir[i] != 0 && i < 100) {
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cprintf("pgdir %d, v=0x%x\n", i, pgdir[i]);
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pte_t *pgtab = (pte_t*) PTE_ADDR(pgdir[i]);
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for (j = 0; j < NPTENTRIES; j++) {
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if (pgtab[j] != 0)
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cprintf("pgtab %d, v=0x%x, addr=0x%x\n", j, PGADDR(i, j, 0),
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PTE_ADDR(pgtab[j]));
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}
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}
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}
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cprintf("printpgdir done\n", pgdir);
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}
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static pte_t *
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walkpgdir(pde_t *pgdir, const void *va, int create)
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{
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uint r;
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pde_t *pde;
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pte_t *pgtab;
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pde = &pgdir[PDX(va)];
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if (*pde & PTE_P) {
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pgtab = (pte_t*) PTE_ADDR(*pde);
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} else if (!create || !(r = (uint) kalloc(PGSIZE)))
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return 0;
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else {
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pgtab = (pte_t*) r;
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// Make sure all those PTE_P bits are zero.
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memset(pgtab, 0, PGSIZE);
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// The permissions here are overly generous, but they can
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// be further restricted by the permissions in the page table
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// entries, if necessary.
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*pde = PADDR(r) | PTE_P | PTE_W | PTE_U;
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}
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return &pgtab[PTX(va)];
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}
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static int
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mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm, int p)
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{
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uint i;
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pte_t *pte;
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if (p)
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cprintf("mappages: pgdir 0x%x la 0x%x sz %d(0x%x) pa 0x%x, perm 0x%x\n",
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pgdir, la, size, size, pa, perm);
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for (i = 0; i < size; i += PGSIZE) {
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if (!(pte = walkpgdir(pgdir, (void*)(la + i), 1)))
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return 0;
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*pte = (pa + i) | perm | PTE_P;
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if (p) cprintf("mappages 0x%x 0x%x pp %d\n", la+i, *pte, PPN(*pte));
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}
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return 1;
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}
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// Set up CPU's kernel segment descriptors.
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// Run once at boot time on each CPU.
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void
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ksegment(void)
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{
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struct cpu *c;
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// Map once virtual addresses to linear addresses using identity map
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c = &cpus[cpunum()];
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c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);
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c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
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c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0x0, 0xffffffff, DPL_USER);
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c->gdt[SEG_UDATA] = SEG(STA_W, 0x0, 0xffffffff, DPL_USER);
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// map cpu, and curproc
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c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);
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lgdt(c->gdt, sizeof(c->gdt));
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loadgs(SEG_KCPU << 3);
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// Initialize cpu-local storage.
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cpu = c;
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proc = 0;
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}
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// Setup address space and current process task state.
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void
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loadvm(struct proc *p)
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{
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pushcli();
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// Setup TSS
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cpu->gdt[SEG_TSS] = SEG16(STS_T32A, &cpu->ts, sizeof(cpu->ts)-1, 0);
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cpu->gdt[SEG_TSS].s = 0;
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cpu->ts.ss0 = SEG_KDATA << 3;
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cpu->ts.esp0 = (uint)proc->kstack + KSTACKSIZE;
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ltr(SEG_TSS << 3);
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if (p->pgdir == 0)
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panic("loadvm: no pgdir\n");
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lcr3(PADDR(p->pgdir)); // switch to new address space
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popcli();
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// Conservatively flush other processor's TLBs (XXX lazy--just 2 cpus)
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if (cpu->id == 0) lapic_tlbflush(1);
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else lapic_tlbflush(0);
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}
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// Setup kernel part of page table. Linear adresses map one-to-one on
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// physical addresses.
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pde_t*
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setupkvm(void)
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{
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pde_t *pgdir;
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// Allocate page directory
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if (!(pgdir = (pde_t *) kalloc(PGSIZE)))
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return 0;
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memset(pgdir, 0, PGSIZE);
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// Map IO space from 640K to 1Mbyte
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if (!mappages(pgdir, (void *)0xA0000, 0x60000, 0xA0000, PTE_W, 0))
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return 0;
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// Map kernel text from kern text addr read-only
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if (!mappages(pgdir, (void *) kerntext, kerntsz, kerntext, 0, 0))
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return 0;
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// Map kernel data form kern data addr R/W
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if (!mappages(pgdir, (void *) kerndata, kerndsz, kerndata, PTE_W, 0))
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return 0;
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// Map dynamically-allocated memory read/write (kernel stacks, user mem)
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if (!mappages(pgdir, (void *) kernend, freesz, PADDR(kernend), PTE_W, 0))
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return 0;
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// Map devices such as ioapic, lapic, ...
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if (!mappages(pgdir, (void *)0xFE000000, 0x2000000, 0xFE000000, PTE_W, 0))
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return 0;
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return pgdir;
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}
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char*
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uva2ka(pde_t *pgdir, char *uva)
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{
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pte_t *pte = walkpgdir(pgdir, uva, 0);
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if (pte == 0) return 0;
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uint pa = PTE_ADDR(*pte);
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return (char *)pa;
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}
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int
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allocuvm(pde_t *pgdir, char *addr, uint sz)
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{
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uint i, n;
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char *mem;
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n = PGROUNDUP(sz);
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if (addr + n >= 0xA0000)
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return 0;
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for (i = 0; i < n; i += PGSIZE) {
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if (!(mem = kalloc(PGSIZE))) { // XXX cleanup what we did?
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return 0;
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}
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memset(mem, 0, PGSIZE);
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mappages(pgdir, addr + i, PGSIZE, PADDR(mem), PTE_W|PTE_U, 0);
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}
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return 1;
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}
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void
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freevm(pde_t *pgdir)
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{
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uint i, j, da;
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if (!pgdir)
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panic("freevm: no pgdir\n");
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for (i = 0; i < NPDENTRIES; i++) {
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da = PTE_ADDR(pgdir[i]);
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if (da != 0) {
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pte_t *pgtab = (pte_t*) da;
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for (j = 0; j < NPTENTRIES; j++) {
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if (pgtab[j] != 0) {
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uint pa = PTE_ADDR(pgtab[j]);
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uint va = PGADDR(i, j, 0);
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if (va >= 0xA0000) // done with user part?
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break;
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kfree((void *) pa, PGSIZE);
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pgtab[j] = 0;
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}
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}
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kfree((void *) da, PGSIZE);
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pgdir[i] = 0;
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}
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}
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kfree((void *) pgdir, PGSIZE);
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}
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int
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loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
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{
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uint i, pa, n;
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pte_t *pte;
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if ((uint)addr % PGSIZE != 0)
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panic("loaduvm: addr must be page aligned\n");
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for (i = 0; i < sz; i += PGSIZE) {
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if (!(pte = walkpgdir(pgdir, addr+i, 0)))
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panic("loaduvm: address should exist\n");
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pa = PTE_ADDR(*pte);
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if (sz - i < PGSIZE) n = sz - i;
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else n = PGSIZE;
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if(readi(ip, (char *)pa, offset+i, n) != n)
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return 0;
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}
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return 1;
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}
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void
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inituvm(pde_t *pgdir, char *addr, char *init, uint sz)
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{
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uint i, pa, n, off;
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pte_t *pte;
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for (i = 0; i < sz; i += PGSIZE) {
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if (!(pte = walkpgdir(pgdir, (void *)(i+addr), 0)))
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panic("inituvm: pte should exist\n");
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off = (i+(uint)addr) % PGSIZE;
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pa = PTE_ADDR(*pte);
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if (sz - i < PGSIZE) n = sz - i;
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else n = PGSIZE;
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memmove((char *)pa+off, init+i, n);
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}
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}
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pde_t*
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copyuvm(pde_t *pgdir, uint sz)
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{
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pde_t *d = setupkvm();
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pte_t *pte;
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uint pa, i;
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char *mem;
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if (!d) return 0;
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for (i = 0; i < sz; i += PGSIZE) {
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if (!(pte = walkpgdir(pgdir, (void *)i, 0)))
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panic("copyuvm: pte should exist\n");
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pa = PTE_ADDR(*pte);
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if (!(mem = kalloc(PGSIZE)))
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return 0;
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memmove(mem, (char *)pa, PGSIZE);
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if (!mappages(d, (void *)i, PGSIZE, PADDR(mem), PTE_W|PTE_U, 0))
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return 0;
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}
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return d;
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}
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void
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pminit(void)
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{
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extern char end[];
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struct proghdr *ph;
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struct elfhdr *elf = (struct elfhdr*)0x10000; // scratch space
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if (elf->magic != ELF_MAGIC || elf->phnum != 2)
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panic("pminit: need a text and data segment\n");
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ph = (struct proghdr*)((uchar*)elf + elf->phoff);
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kernend = ((uint)end + PGSIZE) & ~(PGSIZE-1);
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kerntext = ph[0].va;
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kerndata = ph[1].va;
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kerntsz = kerndata - kerntext;
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kerndsz = kernend - kerndata;
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freesz = 0x300000 - kernend; // XXX no more than 3 Mbyte of phys mem
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cprintf("kerntext@0x%x(sz=0x%x), kerndata@0x%x(sz=0x%x), kernend 0x%x freesz = 0x%x\n",
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kerntext, kerntsz, kerndata, kerndsz, kernend, freesz);
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kinit((char *)kernend, freesz); // XXX should be called once on bootcpu
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}
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// Jump to mainc on a properly-allocated kernel stack
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void
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jkstack(void)
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{
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char *kstack = kalloc(PGSIZE);
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if (!kstack)
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panic("jkstack\n");
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char *top = kstack + PGSIZE;
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jstack((uint) top);
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}
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// Allocate one page table for the machine for the kernel address space
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void
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kvmalloc(void)
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{
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kpgdir = setupkvm();
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}
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// Switch to the kernel page table (used by the scheduler)
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void
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loadkvm(void)
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{
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lcr3(PADDR(kpgdir));
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}
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void
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vminit(void)
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{
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uint cr0;
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loadkvm();
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// Turn on paging.
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cr0 = rcr0();
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cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_TS|CR0_EM|CR0_MP;
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cr0 &= ~(CR0_TS|CR0_EM);
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lcr0(cr0);
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}
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