From b364c4b88156919949aa6f3c805efae009e7459b Mon Sep 17 00:00:00 2001 From: Frans Kaashoek 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); +} +