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| author | Frans Kaashoek <[email protected]> | 2019-07-22 15:38:08 -0400 |
|---|---|---|
| committer | Frans Kaashoek <[email protected]> | 2019-07-22 15:38:08 -0400 |
| commit | b2e9c8eea5d4f4edb43ae7be9e15986dbfce5b95 (patch) | |
| tree | 22f78e4caee4b4481d30a1b83acd13b84841a06e /kernel/vm.c | |
| parent | 38b430687cc248d7d2928e3b7cedf9d220b96013 (diff) | |
| download | xv6-labs-b2e9c8eea5d4f4edb43ae7be9e15986dbfce5b95.tar.gz xv6-labs-b2e9c8eea5d4f4edb43ae7be9e15986dbfce5b95.tar.bz2 xv6-labs-b2e9c8eea5d4f4edb43ae7be9e15986dbfce5b95.zip | |
Clear U bit for second stack page so that it functions as a guard page
Diffstat (limited to 'kernel/vm.c')
| -rw-r--r-- | kernel/vm.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/vm.c b/kernel/vm.c index 96f2ffa..cbea684 100644 --- a/kernel/vm.c +++ b/kernel/vm.c @@ -436,3 +436,13 @@ kernelpa(uint64 va) { pa = PTE2PA(*pte); return pa+off; } + +void +clearpteu(pagetable_t pagetable, uint64 va) { + pte_t *pte; + + pte = walk(pagetable, va, 0); + if(pte == 0) + panic("clearpteu"); + *pte &= ~PTE_U; +} |