Imbus/xv6-riscv-kernel
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xv6: formatting, cleanup, rev5 (take 2)

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This commit is contained in:
Russ Cox 2011-02-19 21:17:55 -05:00
parent 9c4fe7ba10
commit cf4b1ad90b
17 changed files with 193 additions and 197 deletions
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115
vm.c
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@ -6,8 +6,18 @@
#include "proc.h"
#include "elf.h"
extern char data[]; // defined in data.S
static pde_t *kpgdir; // for use in scheduler()
// Allocate one page table for the machine for the kernel address
// space for scheduler processes.
void
kvmalloc(void)
{
kpgdir = setupkvm();
}
// Set up CPU's kernel segment descriptors.
// Run once at boot time on each CPU.
void
@ -72,7 +82,6 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
a = PGROUNDDOWN(la);
last = PGROUNDDOWN(la + size - 1);
for(;;){
pte = walkpgdir(pgdir, a, 1);
if(pte == 0)
@ -110,40 +119,32 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
// range from 0 till 640KB (USERTOP), which where the I/O hole starts
// (both in physical memory and in the kernel's virtual address
// space).
// Allocate one page table for the machine for the kernel address
// space for scheduler processes.
void
kvmalloc(void)
{
kpgdir = setupkvm();
}
static struct kmap {
void *p;
void *e;
int perm;
} kmap[] = {
{(void*)USERTOP, (void*)0x100000, PTE_W}, // I/O space
{(void*)0x100000, data, 0 }, // kernel text, rodata
{data, (void*)PHYSTOP, PTE_W}, // kernel data, memory
{(void*)0xFE000000, 0, PTE_W}, // device mappings
};
// Set up kernel part of a page table.
pde_t*
setupkvm(void)
{
extern char etext[];
char *rwstart;
pde_t *pgdir;
uint rwlen;
struct kmap *k;
rwstart = PGROUNDDOWN(etext);
rwlen = (uint)rwstart - 0x100000;
// Allocate page directory
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) < 0 ||
// Map kernel instructions
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) < 0 ||
// Map devices such as ioapic, lapic, ...
mappages(pgdir, (void*)0xFE000000, 0x2000000, 0xFE000000, PTE_W) < 0)
return 0;
k = kmap;
for(k = kmap; k < &kmap[NELEM(kmap)]; k++)
if(mappages(pgdir, k->p, k->e - k->p, (uint)k->p, k->perm) < 0)
return 0;
return pgdir;
}
@ -162,48 +163,27 @@ vmenable(void)
// Switch h/w page table register to the kernel-only page table,
// for when no process is running.
void
switchkvm()
switchkvm(void)
{
lcr3(PADDR(kpgdir)); // switch to the kernel page table
}
// Switch h/w page table and TSS registers to point to process p.
// Switch TSS and h/w page table to correspond to process p.
void
switchuvm(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("switchuvm: no pgdir\n");
panic("switchuvm: no pgdir");
lcr3(PADDR(p->pgdir)); // switch to new address space
popcli();
}
// Return the physical address that a given user address
// maps to. The result is also a kernel logical address,
// since the kernel maps the physical memory allocated to user
// processes directly.
char*
uva2ka(pde_t *pgdir, char *uva)
{
pte_t *pte;
pte = walkpgdir(pgdir, uva, 0);
if((*pte & PTE_P) == 0)
return 0;
if((*pte & PTE_U) == 0)
return 0;
return (char*)PTE_ADDR(*pte);
}
// Load the initcode into address 0 of pgdir.
// sz must be less than a page.
void
@ -228,10 +208,10 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
pte_t *pte;
if((uint)addr % PGSIZE != 0)
panic("loaduvm: addr must be page aligned\n");
panic("loaduvm: addr must be page aligned");
for(i = 0; i < sz; i += PGSIZE){
if((pte = walkpgdir(pgdir, addr+i, 0)) == 0)
panic("loaduvm: address should exist\n");
panic("loaduvm: address should exist");
pa = PTE_ADDR(*pte);
if(sz - i < PGSIZE)
n = sz - i;
@ -243,10 +223,8 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
return 0;
}
// Allocate memory to the process to bring its size from oldsz to
// newsz. Allocates physical memory and page table entries. oldsz and
// newsz need not be page-aligned, nor does newsz have to be larger
// than oldsz. Returns the new process size or 0 on error.
// Allocate page tables and physical memory to grow process from oldsz to
// newsz, which need not be page aligned. Returns new size or 0 on error.
int
allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
{
@ -330,9 +308,9 @@ copyuvm(pde_t *pgdir, uint sz)
return 0;
for(i = 0; i < sz; i += PGSIZE){
if((pte = walkpgdir(pgdir, (void*)i, 0)) == 0)
panic("copyuvm: pte should exist\n");
panic("copyuvm: pte should exist");
if(!(*pte & PTE_P))
panic("copyuvm: page not present\n");
panic("copyuvm: page not present");
pa = PTE_ADDR(*pte);
if((mem = kalloc()) == 0)
goto bad;
@ -347,16 +325,31 @@ bad:
return 0;
}
// copy some data to user address va in page table pgdir.
// most useful when pgdir is not the current page table.
//PAGEBREAK!
// Map user virtual address to kernel physical address.
char*
uva2ka(pde_t *pgdir, char *uva)
{
pte_t *pte;
pte = walkpgdir(pgdir, uva, 0);
if((*pte & PTE_P) == 0)
return 0;
if((*pte & PTE_U) == 0)
return 0;
return (char*)PTE_ADDR(*pte);
}
// Copy len bytes from p to user address va in page table pgdir.
// Most useful when pgdir is not the current page table.
// uva2ka ensures this only works for PTE_U pages.
int
copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
copyout(pde_t *pgdir, uint va, void *p, uint len)
{
char *buf, *pa0;
uint n, va0;
buf = (char*)xbuf;
buf = (char*)p;
while(len > 0){
va0 = (uint)PGROUNDDOWN(va);
pa0 = uva2ka(pgdir, (char*)va0);