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[Xen-devel] Set NX bit for a PTE.

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: Necrosoft <necrosoft@xxxxxx>
  • Date: Thu, 12 Jun 2008 15:08:30 +0200
  • Delivery-date: Thu, 12 Jun 2008 06:09:08 -0700
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I would set the NX bit for a kernel pte in a PV domain. I try to do that from dom0 walking the page table: when l1e = l1[l1_table_offset_pae(va)]; is reached I try to overwrite this entry (l1[l1_table_offset_pae(va)] = l1e_NX) but I receive a "segmentation fault" and PV domain crash. The address seems to be correct (l1 is not unmapped). In PAE mode page table walk work fine. For example I can print the following informations:

domU Kernel Address: c0105448
l1e: 17489063
l1 address mapped: b7fab000
l1 offset: 105
write on: b7fab105
Segmentation Fault

I can write a pte from dom0 or I must do that only from the hypervisor?

Thank you very much for any idea.

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