diff options
| -rw-r--r-- | mmu.h | 26 | ||||
| -rw-r--r-- | vm.c | 58 |
2 files changed, 24 insertions, 60 deletions
@@ -91,26 +91,22 @@ struct segdesc { // +------+-------+--------------+----------+------------+-------------+ // \-PMX(va)-/\-PDPX(va)--/ \-PDX(va)-/ \-PTX(va)-/ -#define PMX(va) (((uint64)(va) >> PML4XSHIFT) & PXMASK) -#define PDPX(va) (((uint64)(va) >> PDPXSHIFT) & PXMASK) -// page directory index -#define PDX(va) (((uint64)(va) >> PDXSHIFT) & PXMASK) -// page table index -#define PTX(va) (((uint64)(va) >> PTXSHIFT) & PXMASK) - -// construct virtual address from indexes and offset -#define PGADDR(d, t, o) ((uint64)((d) << PDXSHIFT | (t) << PTXSHIFT | (o))) - // Page directory and page table constants. #define NPDENTRIES 512 // # directory entries per page directory #define NPTENTRIES 512 // # PTEs per page table #define PGSIZE 4096 // bytes mapped by a page - -#define PTXSHIFT 12 // offset of PTX in a linear address +#define PGSHIFT 12 // offset of PTX in a linear address #define PDXSHIFT 21 // offset of PDX in a linear address -#define PDPXSHIFT 30 // offset of PDPX in a linear address -#define PML4XSHIFT 39 // offset of PML4X in a linear address -#define PXMASK 0X1FF + +#define PXMASK 0x1FF +#define PXSHIFT(n) (PGSHIFT+(9*(n))) +#define PDX(va) (((uint64)(va) >> PDXSHIFT) & PXMASK) +#define PTX(va) (((uint64)(va) >> PGSHIFT) & PXMASK) +#define PX(n, va) ((((uint64) (va)) >> PXSHIFT(n)) & PXMASK) +#define L_PML4 3 + +// construct virtual address from indexes and offset +#define PGADDR(d, t, o) ((uint64)((d) << PDXSHIFT | (t) << PGSHIFT | (o))) #define PGROUNDUP(sz) (((sz)+PGSIZE-1) & ~(PGSIZE-1)) #define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1)) @@ -66,53 +66,21 @@ seginit(void) static pte_t * walkpgdir(pde_t *pml4, const void *va, int alloc) { - pml4e_t *pml4e; - pdpe_t *pdp; - pdpe_t *pdpe; + pde_t *pgtab = pml4; pde_t *pde; - pde_t *pd; - pte_t *pgtab; - - // level 4 - pml4e = &pml4[PMX(va)]; - if(*pml4e & PTE_P) - pdp = (pdpe_t*)P2V(PTE_ADDR(*pml4e)); - else { - if(!alloc || (pdp = (pdpe_t*)kalloc()) == 0) - return 0; - // Make sure all those PTE_P bits are zero. - memset(pdp, 0, PGSIZE); - // The permissions here are overly generous, but they can - // be further restricted by the permissions in the page table - // entries, if necessary. - *pml4e = V2P(pdp) | PTE_P | PTE_W | PTE_U; - } - - // XXX avoid repetition - - // level 3 - pdpe = &pdp[PDPX(va)]; - if(*pdpe & PTE_P) - pd = (pde_t*)P2V(PTE_ADDR(*pdpe)); - else { - if(!alloc || (pd = (pde_t*)kalloc()) == 0) - return 0; - memset(pd, 0, PGSIZE); - *pdpe = V2P(pd) | PTE_P | PTE_W | PTE_U; - } - - // level 2 - pde = &pd[PDX(va)]; - if(*pde & PTE_P) - pgtab = (pte_t*)P2V(PTE_ADDR(*pde)); - else { - if(!alloc || (pgtab = (pte_t*)kalloc()) == 0) - return 0; - memset(pgtab, 0, PGSIZE); - *pde = V2P(pgtab) | PTE_P | PTE_W | PTE_U; + int level; + + for (level = L_PML4; level > 0; level--) { + pde = &pgtab[PX(level, va)]; + if(*pde & PTE_P) + pgtab = (pte_t*)P2V(PTE_ADDR(*pde)); + else { + if(!alloc || (pgtab = (pte_t*)kalloc()) == 0) + return 0; + memset(pgtab, 0, PGSIZE); + *pde = V2P(pgtab) | PTE_P | PTE_W | PTE_U; + } } - - // level 1 return &pgtab[PTX(va)]; } |