make new code like old code
Variable declarations at top of function,
separate from initialization.
Use == 0 instead of ! for checking pointers.
Consistent spacing around {, *, casts.
Declare 0-parameter functions as (void) not ().
Integer valued functions return -1 on failure, 0 on success.
This commit is contained in:
Russ Cox
parent
240679608c
commit
1a81e38b17
21 changed files with 227 additions and 199 deletions
143
vm.c
143
vm.c
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@ -42,23 +42,21 @@ seginit(void)
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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()))
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return 0;
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else {
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pgtab = (pte_t*) r;
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pgtab = (pte_t*)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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// 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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*pde = PADDR(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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@ -69,13 +67,16 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
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static int
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mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
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{
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char *a = PGROUNDDOWN(la);
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char *last = PGROUNDDOWN(la + size - 1);
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char *a, *last;
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pte_t *pte;
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a = PGROUNDDOWN(la);
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last = PGROUNDDOWN(la + size - 1);
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while(1){
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pte_t *pte = walkpgdir(pgdir, a, 1);
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for(;;){
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pte = walkpgdir(pgdir, a, 1);
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if(pte == 0)
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return 0;
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return -1;
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if(*pte & PTE_P)
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panic("remap");
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*pte = pa | perm | PTE_P;
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@ -84,7 +85,7 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
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a += PGSIZE;
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pa += PGSIZE;
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}
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return 1;
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return 0;
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}
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// The mappings from logical to linear are one to one (i.e.,
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@ -122,23 +123,26 @@ kvmalloc(void)
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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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extern char etext[];
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char *rwstart = PGROUNDDOWN(etext);
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uint rwlen = (uint)rwstart - 0x100000;
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char *rwstart;
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pde_t *pgdir;
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uint rwlen;
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rwstart = PGROUNDDOWN(etext);
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rwlen = (uint)rwstart - 0x100000;
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// Allocate page directory
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if(!(pgdir = (pde_t *) kalloc()))
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if((pgdir = (pde_t*)kalloc()) == 0)
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return 0;
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memset(pgdir, 0, PGSIZE);
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if(// Map IO space from 640K to 1Mbyte
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!mappages(pgdir, (void *)USERTOP, 0x60000, USERTOP, PTE_W) ||
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mappages(pgdir, (void*)USERTOP, 0x60000, USERTOP, PTE_W) < 0 ||
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// Map kernel instructions
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!mappages(pgdir, (void *)0x100000, rwlen, 0x100000, 0) ||
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mappages(pgdir, (void*)0x100000, rwlen, 0x100000, 0) < 0 ||
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// Map kernel data and free memory pool
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!mappages(pgdir, rwstart, PHYSTOP-(uint)rwstart, (uint)rwstart, PTE_W) ||
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mappages(pgdir, rwstart, PHYSTOP-(uint)rwstart, (uint)rwstart, PTE_W) < 0 ||
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// Map devices such as ioapic, lapic, ...
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!mappages(pgdir, (void *)0xFE000000, 0x2000000, 0xFE000000, PTE_W))
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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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@ -189,14 +193,15 @@ switchuvm(struct proc *p)
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// processes directly.
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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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{
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pte_t *pte;
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pte = walkpgdir(pgdir, uva, 0);
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if((*pte & PTE_P) == 0)
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return 0;
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if((*pte & PTE_U) == 0)
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return 0;
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uint pa = PTE_ADDR(*pte);
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return (char *)pa;
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return (char*)PTE_ADDR(*pte);
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}
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// Load the initcode into address 0 of pgdir.
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@ -204,9 +209,11 @@ uva2ka(pde_t *pgdir, char *uva)
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void
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inituvm(pde_t *pgdir, char *init, uint sz)
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{
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char *mem = kalloc();
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if (sz >= PGSIZE)
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char *mem;
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if(sz >= PGSIZE)
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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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memmove(mem, init, sz);
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@ -223,15 +230,17 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
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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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if((pte = walkpgdir(pgdir, addr+i, 0)) == 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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if(sz - i < PGSIZE)
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n = sz - i;
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else
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n = PGSIZE;
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if(readi(ip, (char*)pa, offset+i, n) != n)
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return -1;
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}
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return 1;
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return 0;
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}
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// Allocate memory to the process to bring its size from oldsz to
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@ -241,12 +250,17 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
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int
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allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
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{
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char *a, *last, *mem;
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if(newsz > USERTOP)
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return 0;
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char *a = (char *)PGROUNDUP(oldsz);
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char *last = PGROUNDDOWN(newsz - 1);
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for (; a <= last; a += PGSIZE){
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char *mem = kalloc();
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if(newsz < oldsz)
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return oldsz;
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a = (char*)PGROUNDUP(oldsz);
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last = PGROUNDDOWN(newsz - 1);
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for(; a <= last; a += PGSIZE){
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mem = kalloc();
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if(mem == 0){
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cprintf("allocuvm out of memory\n");
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deallocuvm(pgdir, newsz, oldsz);
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@ -255,7 +269,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
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memset(mem, 0, PGSIZE);
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mappages(pgdir, a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
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}
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return newsz > oldsz ? newsz : oldsz;
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return newsz;
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}
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// Deallocate user pages to bring the process size from oldsz to
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@ -265,19 +279,26 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
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int
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deallocuvm(pde_t *pgdir, uint oldsz, uint newsz)
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{
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char *a = (char *)PGROUNDUP(newsz);
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char *last = PGROUNDDOWN(oldsz - 1);
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char *a, *last;
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pte_t *pte;
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uint pa;
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if(newsz >= oldsz)
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return oldsz;
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a = (char*)PGROUNDUP(newsz);
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last = PGROUNDDOWN(oldsz - 1);
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for(; a <= last; a += PGSIZE){
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pte_t *pte = walkpgdir(pgdir, a, 0);
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pte = walkpgdir(pgdir, a, 0);
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if(pte && (*pte & PTE_P) != 0){
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uint pa = PTE_ADDR(*pte);
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pa = PTE_ADDR(*pte);
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if(pa == 0)
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panic("kfree");
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kfree((void *) pa);
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kfree((char*)pa);
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*pte = 0;
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}
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}
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return newsz < oldsz ? newsz : oldsz;
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return newsz;
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}
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// Free a page table and all the physical memory pages
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@ -287,14 +308,14 @@ freevm(pde_t *pgdir)
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{
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uint i;
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if(!pgdir)
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if(pgdir == 0)
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panic("freevm: no 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((void *) PTE_ADDR(pgdir[i]));
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kfree((char*)PTE_ADDR(pgdir[i]));
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}
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kfree((void *) pgdir);
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kfree((char*)pgdir);
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}
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// Given a parent process's page table, create a copy
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@ -302,22 +323,23 @@ freevm(pde_t *pgdir)
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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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pde_t *d;
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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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if((d = setupkvm()) == 0)
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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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if((pte = walkpgdir(pgdir, (void*)i, 0)) == 0)
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panic("copyuvm: pte should exist\n");
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if(!(*pte & PTE_P))
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panic("copyuvm: page not present\n");
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pa = PTE_ADDR(*pte);
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if(!(mem = kalloc()))
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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))
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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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goto bad;
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}
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return d;
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@ -334,13 +356,16 @@ bad:
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int
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copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
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{
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char *buf = (char *) xbuf;
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char *buf, *pa0;
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uint n, va0;
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buf = (char*)xbuf;
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while(len > 0){
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uint va0 = (uint)PGROUNDDOWN(va);
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char *pa0 = uva2ka(pgdir, (char*) va0);
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va0 = (uint)PGROUNDDOWN(va);
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pa0 = uva2ka(pgdir, (char*)va0);
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if(pa0 == 0)
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return 0;
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uint n = PGSIZE - (va - va0);
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return -1;
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n = PGSIZE - (va - va0);
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if(n > len)
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n = len;
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memmove(pa0 + (va - va0), buf, n);
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@ -348,5 +373,5 @@ copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
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buf += n;
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va = va0 + PGSIZE;
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}
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return 1;
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return 0;
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}
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