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SubjectRe: [PATCH 1/2] x86/sgx: Resolve EAUG race where losing thread returns SIGBUS
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On Mon Apr 29, 2024 at 4:22 PM EEST, Jarkko Sakkinen wrote:
> On Mon Apr 29, 2024 at 4:04 PM EEST, Jarkko Sakkinen wrote:
> > > Fix these two bugs (1) by returning VM_FAULT_NOPAGE to the generic Linux
> > > fault handler so that no signal is sent to userspace, and (2) by
> > > replacing sgx_encl_free_epc_page() with sgx_free_epc_page() so that no
> > > EREMOVE is performed.
> >
> > What is the collateral damage caused by ENCLS[EREMOVE]?
>
> Have you measured cost of eremove on an empty page?
>
> I tried to lookup for a thread from lore because I have a faint memory
> that it was concluded that its cost irrelevant. Please correct if I'm
> wrong.

Also pseudocode for EREMOVE supports this as it just returns without
actually doing anything.

BR, Jarkko

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