From b364c4b88156919949aa6f3c805efae009e7459b Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@31-34-210.wireless.csail.mit.edu>
Date: Fri, 23 Jul 2010 12:52:35 -0400
Subject: [PATCH] oops, vm.c
---
vm.c | 353 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 353 insertions(+)
create mode 100644 vm.c
diff --git a/vm.c b/vm.c
new file mode 100644
index 0000000..f24d510
--- /dev/null
+++ b/vm.c
@@ -0,0 +1,353 @@
+#include "param.h"
+#include "types.h"
+#include "defs.h"
+#include "x86.h"
+#include "mmu.h"
+#include "proc.h"
+#include "elf.h"
+
+static uint kerntext; // linear/physical address of start of kernel text
+static uint kerntsz;
+static uint kerndata;
+static uint kerndsz;
+static uint kernend;
+static uint freesz;
+static pde_t *kpgdir;
+
+void
+printstack()
+{
+ uint *ebp = (uint *) rebp();
+ uint i;
+ cprintf("kernel stack: 0x%x\n", ebp);
+ while (ebp) {
+ if (ebp < (uint *) kerntext) // don't follow user ebp
+ return;
+ cprintf(" ebp %x saved ebp %x eip %x args", ebp, ebp[0], ebp[1]);
+ for (i = 0; i < 4; i++)
+ cprintf(" %x", ebp[2+i]);
+ cprintf("\n");
+ ebp = (uint *) ebp[0];
+ }
+}
+
+void
+printpgdir(pde_t *pgdir)
+{
+ uint i;
+ uint j;
+
+ cprintf("printpgdir 0x%x\n", pgdir);
+ for (i = 0; i < NPDENTRIES; i++) {
+ if (pgdir[i] != 0 && i < 100) {
+ cprintf("pgdir %d, v=0x%x\n", i, pgdir[i]);
+ pte_t *pgtab = (pte_t*) PTE_ADDR(pgdir[i]);
+ for (j = 0; j < NPTENTRIES; j++) {
+ if (pgtab[j] != 0)
+ cprintf("pgtab %d, v=0x%x, addr=0x%x\n", j, PGADDR(i, j, 0),
+ PTE_ADDR(pgtab[j]));
+ }
+ }
+ }
+ cprintf("printpgdir done\n", pgdir);
+}
+
+static pte_t *
+walkpgdir(pde_t *pgdir, const void *va, int create)
+{
+ uint r;
+ pde_t *pde;
+ pte_t *pgtab;
+
+ pde = &pgdir[PDX(va)];
+ if (*pde & PTE_P) {
+ pgtab = (pte_t*) PTE_ADDR(*pde);
+ } else if (!create || !(r = (uint) kalloc(PGSIZE)))
+ return 0;
+ else {
+ pgtab = (pte_t*) r;
+
+ // Make sure all those PTE_P bits are zero.
+ memset(pgtab, 0, PGSIZE);
+
+ // The permissions here are overly generous, but they can
+ // be further restricted by the permissions in the page table
+ // entries, if necessary.
+ *pde = PADDR(r) | PTE_P | PTE_W | PTE_U;
+ }
+ return &pgtab[PTX(va)];
+}
+
+static int
+mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm, int p)
+{
+ uint i;
+ pte_t *pte;
+
+ if (p)
+ cprintf("mappages: pgdir 0x%x la 0x%x sz %d(0x%x) pa 0x%x, perm 0x%x\n",
+ pgdir, la, size, size, pa, perm);
+ for (i = 0; i < size; i += PGSIZE) {
+ if (!(pte = walkpgdir(pgdir, (void*)(la + i), 1)))
+ return 0;
+ *pte = (pa + i) | perm | PTE_P;
+ if (p) cprintf("mappages 0x%x 0x%x pp %d\n", la+i, *pte, PPN(*pte));
+ }
+ return 1;
+}
+
+// Set up CPU's kernel segment descriptors.
+// Run once at boot time on each CPU.
+void
+ksegment(void)
+{
+ struct cpu *c;
+
+ // Map once virtual addresses to linear addresses using identity map
+ c = &cpus[cpunum()];
+ c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);
+ c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
+ c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0x0, 0xffffffff, DPL_USER);
+ c->gdt[SEG_UDATA] = SEG(STA_W, 0x0, 0xffffffff, DPL_USER);
+
+ // map cpu, and curproc
+ c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);
+
+ lgdt(c->gdt, sizeof(c->gdt));
+ loadgs(SEG_KCPU << 3);
+
+ // Initialize cpu-local storage.
+ cpu = c;
+ proc = 0;
+}
+
+// Setup address space and current process task state.
+void
+loadvm(struct proc *p)
+{
+ pushcli();
+
+ // Setup TSS
+ cpu->gdt[SEG_TSS] = SEG16(STS_T32A, &cpu->ts, sizeof(cpu->ts)-1, 0);
+ cpu->gdt[SEG_TSS].s = 0;
+ cpu->ts.ss0 = SEG_KDATA << 3;
+ cpu->ts.esp0 = (uint)proc->kstack + KSTACKSIZE;
+ ltr(SEG_TSS << 3);
+
+ if (p->pgdir == 0)
+ panic("loadvm: no pgdir\n");
+
+ lcr3(PADDR(p->pgdir)); // switch to new address space
+ popcli();
+
+ // Conservatively flush other processor's TLBs (XXX lazy--just 2 cpus)
+ if (cpu->id == 0) lapic_tlbflush(1);
+ else lapic_tlbflush(0);
+}
+
+// Setup kernel part of page table. Linear adresses map one-to-one on
+// physical addresses.
+pde_t*
+setupkvm(void)
+{
+ pde_t *pgdir;
+
+ // Allocate page directory
+ if (!(pgdir = (pde_t *) kalloc(PGSIZE)))
+ return 0;
+ memset(pgdir, 0, PGSIZE);
+ // Map IO space from 640K to 1Mbyte
+ if (!mappages(pgdir, (void *)0xA0000, 0x60000, 0xA0000, PTE_W, 0))
+ return 0;
+ // Map kernel text from kern text addr read-only
+ if (!mappages(pgdir, (void *) kerntext, kerntsz, kerntext, 0, 0))
+ return 0;
+ // Map kernel data form kern data addr R/W
+ if (!mappages(pgdir, (void *) kerndata, kerndsz, kerndata, PTE_W, 0))
+ return 0;
+ // Map dynamically-allocated memory read/write (kernel stacks, user mem)
+ if (!mappages(pgdir, (void *) kernend, freesz, PADDR(kernend), PTE_W, 0))
+ return 0;
+ // Map devices such as ioapic, lapic, ...
+ if (!mappages(pgdir, (void *)0xFE000000, 0x2000000, 0xFE000000, PTE_W, 0))
+ return 0;
+ return pgdir;
+}
+
+char*
+uva2ka(pde_t *pgdir, char *uva)
+{
+ pte_t *pte = walkpgdir(pgdir, uva, 0);
+ if (pte == 0) return 0;
+ uint pa = PTE_ADDR(*pte);
+ return (char *)pa;
+}
+
+int
+allocuvm(pde_t *pgdir, char *addr, uint sz)
+{
+ uint i, n;
+ char *mem;
+
+ n = PGROUNDUP(sz);
+ if (addr + n >= 0xA0000)
+ return 0;
+ for (i = 0; i < n; i += PGSIZE) {
+ if (!(mem = kalloc(PGSIZE))) { // XXX cleanup what we did?
+ return 0;
+ }
+ memset(mem, 0, PGSIZE);
+ mappages(pgdir, addr + i, PGSIZE, PADDR(mem), PTE_W|PTE_U, 0);
+ }
+ return 1;
+}
+
+void
+freevm(pde_t *pgdir)
+{
+ uint i, j, da;
+
+ if (!pgdir)
+ panic("freevm: no pgdir\n");
+ for (i = 0; i < NPDENTRIES; i++) {
+ da = PTE_ADDR(pgdir[i]);
+ if (da != 0) {
+ pte_t *pgtab = (pte_t*) da;
+ for (j = 0; j < NPTENTRIES; j++) {
+ if (pgtab[j] != 0) {
+ uint pa = PTE_ADDR(pgtab[j]);
+ uint va = PGADDR(i, j, 0);
+ if (va >= 0xA0000) // done with user part?
+ break;
+ kfree((void *) pa, PGSIZE);
+ pgtab[j] = 0;
+ }
+ }
+ kfree((void *) da, PGSIZE);
+ pgdir[i] = 0;
+ }
+ }
+ kfree((void *) pgdir, PGSIZE);
+}
+
+int
+loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
+{
+ uint i, pa, n;
+ pte_t *pte;
+
+ if ((uint)addr % PGSIZE != 0)
+ panic("loaduvm: addr must be page aligned\n");
+ for (i = 0; i < sz; i += PGSIZE) {
+ if (!(pte = walkpgdir(pgdir, addr+i, 0)))
+ panic("loaduvm: address should exist\n");
+ pa = PTE_ADDR(*pte);
+ if (sz - i < PGSIZE) n = sz - i;
+ else n = PGSIZE;
+ if(readi(ip, (char *)pa, offset+i, n) != n)
+ return 0;
+ }
+ return 1;
+}
+
+void
+inituvm(pde_t *pgdir, char *addr, char *init, uint sz)
+{
+ uint i, pa, n, off;
+ pte_t *pte;
+
+ for (i = 0; i < sz; i += PGSIZE) {
+ if (!(pte = walkpgdir(pgdir, (void *)(i+addr), 0)))
+ panic("inituvm: pte should exist\n");
+ off = (i+(uint)addr) % PGSIZE;
+ pa = PTE_ADDR(*pte);
+ if (sz - i < PGSIZE) n = sz - i;
+ else n = PGSIZE;
+ memmove((char *)pa+off, init+i, n);
+ }
+}
+
+pde_t*
+copyuvm(pde_t *pgdir, uint sz)
+{
+ pde_t *d = setupkvm();
+ pte_t *pte;
+ uint pa, i;
+ char *mem;
+
+ if (!d) return 0;
+ for (i = 0; i < sz; i += PGSIZE) {
+ if (!(pte = walkpgdir(pgdir, (void *)i, 0)))
+ panic("copyuvm: pte should exist\n");
+ pa = PTE_ADDR(*pte);
+ if (!(mem = kalloc(PGSIZE)))
+ return 0;
+ memmove(mem, (char *)pa, PGSIZE);
+ if (!mappages(d, (void *)i, PGSIZE, PADDR(mem), PTE_W|PTE_U, 0))
+ return 0;
+ }
+ return d;
+}
+
+void
+pminit(void)
+{
+ extern char end[];
+ struct proghdr *ph;
+ struct elfhdr *elf = (struct elfhdr*)0x10000; // scratch space
+
+ if (elf->magic != ELF_MAGIC || elf->phnum != 2)
+ panic("pminit: need a text and data segment\n");
+
+ ph = (struct proghdr*)((uchar*)elf + elf->phoff);
+ kernend = ((uint)end + PGSIZE) & ~(PGSIZE-1);
+ kerntext = ph[0].va;
+ kerndata = ph[1].va;
+ kerntsz = kerndata - kerntext;
+ kerndsz = kernend - kerndata;
+ freesz = 0x300000 - kernend; // XXX no more than 3 Mbyte of phys mem
+
+ cprintf("kerntext@0x%x(sz=0x%x), kerndata@0x%x(sz=0x%x), kernend 0x%x freesz = 0x%x\n",
+ kerntext, kerntsz, kerndata, kerndsz, kernend, freesz);
+
+ kinit((char *)kernend, freesz); // XXX should be called once on bootcpu
+}
+
+// Jump to mainc on a properly-allocated kernel stack
+void
+jkstack(void)
+{
+ char *kstack = kalloc(PGSIZE);
+ if (!kstack)
+ panic("jkstack\n");
+ char *top = kstack + PGSIZE;
+ jstack((uint) top);
+}
+
+// Allocate one page table for the machine for the kernel address space
+void
+kvmalloc(void)
+{
+ kpgdir = setupkvm();
+}
+
+// Switch to the kernel page table (used by the scheduler)
+void
+loadkvm(void)
+{
+ lcr3(PADDR(kpgdir));
+}
+
+void
+vminit(void)
+{
+ uint cr0;
+
+ loadkvm();
+ // Turn on paging.
+ cr0 = rcr0();
+ cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_TS|CR0_EM|CR0_MP;
+ cr0 &= ~(CR0_TS|CR0_EM);
+ lcr0(cr0);
+}
+
--
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