Map kernel high
Very important to give qemu memory through PHYSTOP :(
This commit is contained in:
Frans Kaashoek
parent
dccb915282
commit
9aa0337dc1
20 changed files with 208 additions and 71 deletions
129
vm.c
129
vm.c
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@ -2,20 +2,71 @@
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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 "memlayout.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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extern char data[]; // defined in data.S
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static pde_t *kpgdir; // for use in scheduler()
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struct segdesc gdt[NSEGS];
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// Allocate one page table for the machine for the kernel address
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// space for scheduler processes.
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void
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kvmalloc(void)
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// page map for during boot
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// XXX build a static page table in assembly
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static void
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pgmap(void *va, void *last, uint pa)
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{
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kpgdir = setupkvm();
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pde_t *pde;
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pte_t *pgtab;
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pte_t *pte;
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for(;;){
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pde = &kpgdir[PDX(va)];
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pde_t pdev = *pde;
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if (pdev == 0) {
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pgtab = (pte_t *) pgalloc();
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*pde = v2p(pgtab) | PTE_P | PTE_W;
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} else {
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pgtab = (pte_t*)p2v(PTE_ADDR(pdev));
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}
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pte = &pgtab[PTX(va)];
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*pte = pa | PTE_W | PTE_P;
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if(va == last)
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break;
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va += PGSIZE;
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pa += PGSIZE;
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}
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}
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// set up a page table to get off the ground
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void
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pginit(char* (*alloc)(void))
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{
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uint cr0;
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kpgdir = (pde_t *) alloc();
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pgmap((void *) 0, (void *) PHYSTOP, 0); // map pa 0 at va 0
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pgmap((void *) KERNBASE, (void *) (KERNBASE+PHYSTOP), 0); // map pa 0 at va KERNBASE
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pgmap((void*)0xFE000000, 0, 0xFE000000);
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switchkvm(); // load kpgdir into cr3
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cr0 = rcr0();
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cr0 |= CR0_PG;
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lcr0(cr0); // paging on
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// new gdt
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gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);
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gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
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lgdt((void *)v2p(gdt), sizeof(gdt));
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loadgs(SEG_KDATA << 3);
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loadfs(SEG_KDATA << 3);
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loades(SEG_KDATA << 3);
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loadds(SEG_KDATA << 3);
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loadss(SEG_KDATA << 3);
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__asm volatile("ljmp %0,$1f\n 1:\n" :: "i" (SEG_KCODE << 3)); // reload cs
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}
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// Set up CPU's kernel segment descriptors.
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@ -57,7 +108,7 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
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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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pgtab = (pte_t*)p2v(PTE_ADDR(*pde));
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} else {
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if(!create || (pgtab = (pte_t*)kalloc()) == 0)
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return 0;
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@ -66,7 +117,7 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
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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(pgtab) | PTE_P | PTE_W | PTE_U;
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*pde = v2p(pgtab) | 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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@ -105,29 +156,30 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
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// page protection bits prevent it from using anything other
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// than its memory.
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//
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//
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// setupkvm() and exec() set up every page table like this:
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// 0..640K : user memory (text, data, stack, heap)
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// 640K..1M : mapped direct (for IO space)
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// 1M..end : mapped direct (for the kernel's text and data)
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// end..PHYSTOP : mapped direct (kernel heap and user pages)
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// 0..KERNBASE : user memory (text, data, stack, heap), mapped to some phys mem
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// KERNBASE+640K..KERNBASE+1M: mapped to 640K..1M
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// KERNBASE+1M..KERNBASE+end : mapped to 1M..end
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// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (free memory)
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// 0xfe000000..0 : mapped direct (devices such as ioapic)
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//
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// The kernel allocates memory for its heap and for user memory
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// between kernend and the end of physical memory (PHYSTOP).
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// The virtual address space of each user program includes the kernel
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// (which is inaccessible in user mode). The user program addresses
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// range from 0 till 640KB (USERTOP), which where the I/O hole starts
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// (both in physical memory and in the kernel's virtual address
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// space).
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// (which is inaccessible in user mode). The user program sits in
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// the bottom of the address space, and the kernel at the top at KERNBASE.
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static struct kmap {
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void *p;
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void *e;
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void *l;
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uint p;
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uint e;
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int perm;
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} kmap[] = {
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{(void*)USERTOP, (void*)0x100000, PTE_W}, // I/O space
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{(void*)0x100000, data, 0 }, // kernel text, rodata
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{data, (void*)PHYSTOP, PTE_W}, // kernel data, memory
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{(void*)0xFE000000, 0, PTE_W}, // device mappings
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{ (void *)IOSPACEB, IOSPACEB, IOSPACEE, PTE_W}, // I/O space
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{ P2V(IOSPACEB), IOSPACEB, IOSPACEE, PTE_W}, // I/O space
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{ (void *)KERNLINK, V2P(KERNLINK), V2P(data), 0}, // kernel text, rodata
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{ data, V2P(data), PHYSTOP, PTE_W}, // kernel data, memory
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{ (void*)0xFE000000, 0xFE000000, 0, PTE_W}, // device mappings
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};
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// Set up kernel part of a page table.
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@ -142,12 +194,21 @@ setupkvm(void)
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memset(pgdir, 0, PGSIZE);
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k = kmap;
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for(k = kmap; k < &kmap[NELEM(kmap)]; k++)
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if(mappages(pgdir, k->p, k->e - k->p, (uint)k->p, k->perm) < 0)
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if(mappages(pgdir, k->l, k->e - k->p, (uint)k->p, k->perm) < 0)
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return 0;
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return pgdir;
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}
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// Allocate one page table for the machine for the kernel address
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// space for scheduler processes.
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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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switchkvm();
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}
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// Turn on paging.
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void
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vmenable(void)
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@ -158,6 +219,16 @@ vmenable(void)
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cr0 = rcr0();
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cr0 |= CR0_PG;
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lcr0(cr0);
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struct cpu *c = &cpus[0];
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lgdt((void *)v2p((void *)(c->gdt)), sizeof(c->gdt));
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loadgs(SEG_KCPU << 3);
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loadfs(SEG_KDATA << 3);
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loades(SEG_KDATA << 3);
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loadds(SEG_KDATA << 3);
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loadss(SEG_KDATA << 3);
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__asm volatile("ljmp %0,$1f\n 1:\n" :: "i" (SEG_KCODE << 3)); // reload cs
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}
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// Switch h/w page table register to the kernel-only page table,
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@ -165,7 +236,7 @@ vmenable(void)
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void
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switchkvm(void)
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{
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lcr3(PADDR(kpgdir)); // switch to the kernel page table
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lcr3(v2p(kpgdir)); // switch to the kernel page table
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}
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// Switch TSS and h/w page table to correspond to process p.
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@ -180,7 +251,7 @@ switchuvm(struct proc *p)
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ltr(SEG_TSS << 3);
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if(p->pgdir == 0)
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panic("switchuvm: no pgdir");
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lcr3(PADDR(p->pgdir)); // switch to new address space
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lcr3(v2p(p->pgdir)); // switch to new address space
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popcli();
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}
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@ -195,7 +266,7 @@ inituvm(pde_t *pgdir, char *init, uint sz)
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panic("inituvm: more than a page");
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mem = kalloc();
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memset(mem, 0, PGSIZE);
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mappages(pgdir, 0, PGSIZE, PADDR(mem), PTE_W|PTE_U);
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mappages(pgdir, 0, PGSIZE, v2p(mem), PTE_W|PTE_U);
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memmove(mem, init, sz);
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}
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@ -245,7 +316,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
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return 0;
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}
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memset(mem, 0, PGSIZE);
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mappages(pgdir, (char*)a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
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mappages(pgdir, (char*)a, PGSIZE, v2p(mem), PTE_W|PTE_U);
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}
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return newsz;
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}
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@ -289,7 +360,7 @@ freevm(pde_t *pgdir)
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deallocuvm(pgdir, USERTOP, 0);
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for(i = 0; i < NPDENTRIES; i++){
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if(pgdir[i] & PTE_P)
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kfree((char*)PTE_ADDR(pgdir[i]));
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kfree(p2v(PTE_ADDR(pgdir[i])));
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}
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kfree((char*)pgdir);
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}
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@ -315,7 +386,7 @@ copyuvm(pde_t *pgdir, uint sz)
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if((mem = kalloc()) == 0)
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goto bad;
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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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if(mappages(d, (void*)i, PGSIZE, v2p(mem), PTE_W|PTE_U) < 0)
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goto bad;
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}
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return d;
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