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authorRobert Morris <[email protected]>2010-09-27 16:14:33 -0400
committerRobert Morris <[email protected]>2010-09-27 16:14:33 -0400
commit4655d42e3b65f906eae8c815fb78331790f6e423 (patch)
treede5b3e4e74c992fd3cd8fef0a2d37cb805c659ac /vm.c
parenta9183883b88bfccd1c6a62e27621b2c892d50b67 (diff)
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copyout() copies data to a va in a pagetable, for exec() &c
usertest that passes too many arguments, break exec
Diffstat (limited to 'vm.c')
-rw-r--r--vm.c32
1 files changed, 28 insertions, 4 deletions
diff --git a/vm.c b/vm.c
index cd6b255..551efbf 100644
--- a/vm.c
+++ b/vm.c
@@ -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;
+}