Re: [RFC PATCH 2/9] x86/sgx: Do not naturally align MAP_FIXED address
From: Jarkko Sakkinen
Date: Thu Jun 06 2019 - 11:41:47 EST
On Wed, Jun 05, 2019 at 01:14:04PM -0700, Andy Lutomirski wrote:
> > On Jun 5, 2019, at 8:17 AM, Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> >> On Tue, Jun 04, 2019 at 10:10:22PM +0000, Xing, Cedric wrote:
> >> A bit off topic here. This mmap()/mprotect() discussion reminds me a
> >> question (guess for Jarkko): Now that vma->vm_file->private_data keeps
> >> a pointer to the enclave, why do we store it again in vma->vm_private?
> >> It isn't a big deal but non-NULL vm_private does prevent mprotect()
> >> from merging adjacent VMAs.
> > Same semantics as with a regular mmap i.e. you can close the file and
> > still use the mapping.
> The file should be properly refcounted â vm_file should not go away while itâs mapped.
Right, makes sense. It is easy one to change essentially just removing
internal refcount from sgx_encl and using file for the same. I'll update
this to my tree along with the changes to remove LKM/ACPI bits ASAP.