summaryrefslogtreecommitdiff
path: root/vm.c
diff options
context:
space:
mode:
authorRuss Cox <[email protected]>2011-01-11 13:01:13 -0500
committerRuss Cox <[email protected]>2011-01-11 13:01:13 -0500
commit1a81e38b17144624415d252a521fd5a06079d681 (patch)
treeea7d895bcf77aa25861c09ee490488b6f729e0f3 /vm.c
parent240679608cd46649d1144408f28f83141f9f3a86 (diff)
downloadxv6-labs-1a81e38b17144624415d252a521fd5a06079d681.tar.gz
xv6-labs-1a81e38b17144624415d252a521fd5a06079d681.tar.bz2
xv6-labs-1a81e38b17144624415d252a521fd5a06079d681.zip
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.
Diffstat (limited to 'vm.c')
-rw-r--r--vm.c143
1 files changed, 84 insertions, 59 deletions
diff --git a/vm.c b/vm.c
index 551efbf..940cc2f 100644
--- a/vm.c
+++ b/vm.c
@@ -42,23 +42,21 @@ seginit(void)
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()))
- return 0;
- else {
- pgtab = (pte_t*) r;
+ pgtab = (pte_t*)PTE_ADDR(*pde);
+ } else {
+ if(!create || (pgtab = (pte_t*)kalloc()) == 0)
+ return 0;
// 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;
+ *pde = PADDR(pgtab) | PTE_P | PTE_W | PTE_U;
}
return &pgtab[PTX(va)];
}
@@ -69,13 +67,16 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
static int
mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
{
- char *a = PGROUNDDOWN(la);
- char *last = PGROUNDDOWN(la + size - 1);
+ char *a, *last;
+ pte_t *pte;
+
+ a = PGROUNDDOWN(la);
+ last = PGROUNDDOWN(la + size - 1);
- while(1){
- pte_t *pte = walkpgdir(pgdir, a, 1);
+ for(;;){
+ pte = walkpgdir(pgdir, a, 1);
if(pte == 0)
- return 0;
+ return -1;
if(*pte & PTE_P)
panic("remap");
*pte = pa | perm | PTE_P;
@@ -84,7 +85,7 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
a += PGSIZE;
pa += PGSIZE;
}
- return 1;
+ return 0;
}
// The mappings from logical to linear are one to one (i.e.,
@@ -122,23 +123,26 @@ kvmalloc(void)
pde_t*
setupkvm(void)
{
- pde_t *pgdir;
extern char etext[];
- char *rwstart = PGROUNDDOWN(etext);
- uint rwlen = (uint)rwstart - 0x100000;
+ char *rwstart;
+ pde_t *pgdir;
+ uint rwlen;
+
+ rwstart = PGROUNDDOWN(etext);
+ rwlen = (uint)rwstart - 0x100000;
// Allocate page directory
- if(!(pgdir = (pde_t *) kalloc()))
+ if((pgdir = (pde_t*)kalloc()) == 0)
return 0;
memset(pgdir, 0, PGSIZE);
if(// Map IO space from 640K to 1Mbyte
- !mappages(pgdir, (void *)USERTOP, 0x60000, USERTOP, PTE_W) ||
+ mappages(pgdir, (void*)USERTOP, 0x60000, USERTOP, PTE_W) < 0 ||
// Map kernel instructions
- !mappages(pgdir, (void *)0x100000, rwlen, 0x100000, 0) ||
+ mappages(pgdir, (void*)0x100000, rwlen, 0x100000, 0) < 0 ||
// Map kernel data and free memory pool
- !mappages(pgdir, rwstart, PHYSTOP-(uint)rwstart, (uint)rwstart, PTE_W) ||
+ mappages(pgdir, rwstart, PHYSTOP-(uint)rwstart, (uint)rwstart, PTE_W) < 0 ||
// Map devices such as ioapic, lapic, ...
- !mappages(pgdir, (void *)0xFE000000, 0x2000000, 0xFE000000, PTE_W))
+ mappages(pgdir, (void*)0xFE000000, 0x2000000, 0xFE000000, PTE_W) < 0)
return 0;
return pgdir;
}
@@ -189,14 +193,15 @@ switchuvm(struct proc *p)
// processes directly.
char*
uva2ka(pde_t *pgdir, char *uva)
-{
- pte_t *pte = walkpgdir(pgdir, uva, 0);
+{
+ pte_t *pte;
+
+ pte = walkpgdir(pgdir, uva, 0);
if((*pte & PTE_P) == 0)
return 0;
if((*pte & PTE_U) == 0)
return 0;
- uint pa = PTE_ADDR(*pte);
- return (char *)pa;
+ return (char*)PTE_ADDR(*pte);
}
// Load the initcode into address 0 of pgdir.
@@ -204,9 +209,11 @@ uva2ka(pde_t *pgdir, char *uva)
void
inituvm(pde_t *pgdir, char *init, uint sz)
{
- char *mem = kalloc();
- if (sz >= PGSIZE)
+ char *mem;
+
+ if(sz >= PGSIZE)
panic("inituvm: more than a page");
+ mem = kalloc();
memset(mem, 0, PGSIZE);
mappages(pgdir, 0, PGSIZE, PADDR(mem), PTE_W|PTE_U);
memmove(mem, init, sz);
@@ -223,15 +230,17 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
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)))
+ if((pte = walkpgdir(pgdir, addr+i, 0)) == 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;
+ if(sz - i < PGSIZE)
+ n = sz - i;
+ else
+ n = PGSIZE;
+ if(readi(ip, (char*)pa, offset+i, n) != n)
+ return -1;
}
- return 1;
+ return 0;
}
// Allocate memory to the process to bring its size from oldsz to
@@ -241,12 +250,17 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
int
allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
{
+ char *a, *last, *mem;
+
if(newsz > USERTOP)
return 0;
- char *a = (char *)PGROUNDUP(oldsz);
- char *last = PGROUNDDOWN(newsz - 1);
- for (; a <= last; a += PGSIZE){
- char *mem = kalloc();
+ if(newsz < oldsz)
+ return oldsz;
+
+ a = (char*)PGROUNDUP(oldsz);
+ last = PGROUNDDOWN(newsz - 1);
+ for(; a <= last; a += PGSIZE){
+ mem = kalloc();
if(mem == 0){
cprintf("allocuvm out of memory\n");
deallocuvm(pgdir, newsz, oldsz);
@@ -255,7 +269,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
memset(mem, 0, PGSIZE);
mappages(pgdir, a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
}
- return newsz > oldsz ? newsz : oldsz;
+ return newsz;
}
// Deallocate user pages to bring the process size from oldsz to
@@ -265,19 +279,26 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
int
deallocuvm(pde_t *pgdir, uint oldsz, uint newsz)
{
- char *a = (char *)PGROUNDUP(newsz);
- char *last = PGROUNDDOWN(oldsz - 1);
+ char *a, *last;
+ pte_t *pte;
+ uint pa;
+
+ if(newsz >= oldsz)
+ return oldsz;
+
+ a = (char*)PGROUNDUP(newsz);
+ last = PGROUNDDOWN(oldsz - 1);
for(; a <= last; a += PGSIZE){
- pte_t *pte = walkpgdir(pgdir, a, 0);
+ pte = walkpgdir(pgdir, a, 0);
if(pte && (*pte & PTE_P) != 0){
- uint pa = PTE_ADDR(*pte);
+ pa = PTE_ADDR(*pte);
if(pa == 0)
panic("kfree");
- kfree((void *) pa);
+ kfree((char*)pa);
*pte = 0;
}
}
- return newsz < oldsz ? newsz : oldsz;
+ return newsz;
}
// Free a page table and all the physical memory pages
@@ -287,14 +308,14 @@ freevm(pde_t *pgdir)
{
uint i;
- if(!pgdir)
+ if(pgdir == 0)
panic("freevm: no pgdir");
deallocuvm(pgdir, USERTOP, 0);
for(i = 0; i < NPDENTRIES; i++){
if(pgdir[i] & PTE_P)
- kfree((void *) PTE_ADDR(pgdir[i]));
+ kfree((char*)PTE_ADDR(pgdir[i]));
}
- kfree((void *) pgdir);
+ kfree((char*)pgdir);
}
// Given a parent process's page table, create a copy
@@ -302,22 +323,23 @@ freevm(pde_t *pgdir)
pde_t*
copyuvm(pde_t *pgdir, uint sz)
{
- pde_t *d = setupkvm();
+ pde_t *d;
pte_t *pte;
uint pa, i;
char *mem;
- if(!d) return 0;
+ if((d = setupkvm()) == 0)
+ return 0;
for(i = 0; i < sz; i += PGSIZE){
- if(!(pte = walkpgdir(pgdir, (void *)i, 0)))
+ if((pte = walkpgdir(pgdir, (void*)i, 0)) == 0)
panic("copyuvm: pte should exist\n");
if(!(*pte & PTE_P))
panic("copyuvm: page not present\n");
pa = PTE_ADDR(*pte);
- if(!(mem = kalloc()))
+ if((mem = kalloc()) == 0)
goto bad;
- memmove(mem, (char *)pa, PGSIZE);
- if(!mappages(d, (void *)i, PGSIZE, PADDR(mem), PTE_W|PTE_U))
+ memmove(mem, (char*)pa, PGSIZE);
+ if(mappages(d, (void*)i, PGSIZE, PADDR(mem), PTE_W|PTE_U) < 0)
goto bad;
}
return d;
@@ -334,13 +356,16 @@ bad:
int
copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
{
- char *buf = (char *) xbuf;
+ char *buf, *pa0;
+ uint n, va0;
+
+ buf = (char*)xbuf;
while(len > 0){
- uint va0 = (uint)PGROUNDDOWN(va);
- char *pa0 = uva2ka(pgdir, (char*) va0);
+ va0 = (uint)PGROUNDDOWN(va);
+ pa0 = uva2ka(pgdir, (char*)va0);
if(pa0 == 0)
- return 0;
- uint n = PGSIZE - (va - va0);
+ return -1;
+ n = PGSIZE - (va - va0);
if(n > len)
n = len;
memmove(pa0 + (va - va0), buf, n);
@@ -348,5 +373,5 @@ copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
buf += n;
va = va0 + PGSIZE;
}
- return 1;
+ return 0;
}