Imbus/xv6-riscv-kernel
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copyout() copies data to a va in a pagetable, for exec() &c

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usertest that passes too many arguments, break exec
This commit is contained in:
Robert Morris 2010-09-27 16:14:33 -04:00
parent a9183883b8
commit 4655d42e3b
6 changed files with 91 additions and 41 deletions
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32
vm.c
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@ -6,8 +6,6 @@
#include "proc.h"
#include "elf.h"
#define USERTOP 0xA0000
static pde_t *kpgdir; // for use in scheduler()
// Set up CPU's kernel segment descriptors.
@ -126,7 +124,7 @@ setupkvm(void)
{
pde_t *pgdir;
extern char etext[];
char *rwstart = PGROUNDDOWN(etext) - PGSIZE;
char *rwstart = PGROUNDDOWN(etext);
uint rwlen = (uint)rwstart - 0x100000;
// Allocate page directory
@ -193,7 +191,10 @@ char*
uva2ka(pde_t *pgdir, char *uva)
{
pte_t *pte = walkpgdir(pgdir, uva, 0);
if(pte == 0) return 0;
if((*pte & PTE_P) == 0)
return 0;
if((*pte & PTE_U) == 0)
return 0;
uint pa = PTE_ADDR(*pte);
return (char *)pa;
}
@ -326,3 +327,26 @@ bad:
return 0;
}
// copy some data to user address va in page table pgdir.
// most useful when pgdir is not the current page table.
// returns 1 if everthing OK, 0 on error.
// uva2ka ensures this only works for PTE_U pages.
int
copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
{
char *buf = (char *) xbuf;
while(len > 0){
uint va0 = (uint)PGROUNDDOWN(va);
char *pa0 = uva2ka(pgdir, (char*) va0);
if(pa0 == 0)
return 0;
uint n = PGSIZE - (va - va0);
if(n > len)
n = len;
memmove(pa0 + (va - va0), buf, n);
len -= n;
buf += n;
va = va0 + PGSIZE;
}
return 1;
}