Imbus/xv6-riscv-kernel
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Eliminate USERTOP; no use for it.

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This commit is contained in:
Frans Kaashoek 2011-08-24 10:24:40 -04:00
parent 194f8bf739
commit 6f2327580f
2 changed files with 3 additions and 4 deletions
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6
vm.c
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@ -99,7 +99,7 @@ mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm, char* (*alloc)(vo
// than its memory.
//
// setupkvm() and exec() set up every page table like this:
// 0..USERTOP : user memory (text, data, stack, heap), mapped to some unused phys mem
// 0..KERNBASE : user memory (text, data, stack, heap), mapped to some unused phys mem
// KERNBASE..KERNBASE+EXTMEM: mapped to 0..EXTMEM (below extended memory)
// KERNBASE+EXTMEM..KERNBASE+end : mapped to EXTMEM..end (mapped without write permission)
// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (rw data + free memory)
@ -223,7 +223,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
char *mem;
uint a;
if(newsz > USERTOP)
if(newsz >= KERNBASE)
return 0;
if(newsz < oldsz)
return oldsz;
@ -279,7 +279,7 @@ freevm(pde_t *pgdir)
if(pgdir == 0)
panic("freevm: no pgdir");
deallocuvm(pgdir, USERTOP, 0);
deallocuvm(pgdir, KERNBASE, 0);
for(i = 0; i < NPDENTRIES; i++){
if(pgdir[i] & PTE_P) {
char * v = p2v(PTE_ADDR(pgdir[i]));