diff options
Diffstat (limited to 'kernel/vm.c')
| -rw-r--r-- | kernel/vm.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/kernel/vm.c b/kernel/vm.c index c5da0c1..636f11a 100644 --- a/kernel/vm.c +++ b/kernel/vm.c @@ -16,9 +16,7 @@ extern char etext[]; // kernel.ld sets this to end of kernel code. extern char trampoline[]; // trampoline.S /* - * create a direct-map page table for the kernel and - * turn on paging. called early, in supervisor mode. - * the page allocator is already initialized. + * create a direct-map page table for the kernel. */ void kvminit() @@ -67,10 +65,10 @@ kvminithart() // A 64-bit virtual address is split into five fields: // 39..63 -- must be zero. // 30..38 -- 9 bits of level-2 index. -// 21..39 -- 9 bits of level-1 index. +// 21..29 -- 9 bits of level-1 index. // 12..20 -- 9 bits of level-0 index. -// 0..12 -- 12 bits of byte offset within the page. -static pte_t * +// 0..11 -- 12 bits of byte offset within the page. +pte_t * walk(pagetable_t pagetable, uint64 va, int alloc) { if(va >= MAXVA) @@ -278,7 +276,7 @@ uvmdealloc(pagetable_t pagetable, uint64 oldsz, uint64 newsz) // Recursively free page-table pages. // All leaf mappings must already have been removed. -static void +void freewalk(pagetable_t pagetable) { // there are 2^9 = 512 PTEs in a page table. @@ -301,7 +299,8 @@ freewalk(pagetable_t pagetable) void uvmfree(pagetable_t pagetable, uint64 sz) { - uvmunmap(pagetable, 0, sz, 1); + if(sz > 0) + uvmunmap(pagetable, 0, sz, 1); freewalk(pagetable); } |