Messages in this thread | | | Subject | Re: [RFC][PATCH v2 11/21] x86/pti: Extend PTI user mappings | From | Alexandre Chartre <> | Date | Mon, 16 Nov 2020 21:21:03 +0100 |
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On 11/16/20 8:48 PM, Andy Lutomirski wrote: > On Mon, Nov 16, 2020 at 6:49 AM Alexandre Chartre > <alexandre.chartre@oracle.com> wrote: >> >> Extend PTI user mappings so that more kernel entry code can be executed >> with the user page-table. To do so, we need to map syscall and interrupt >> entry code, per cpu offsets (__per_cpu_offset, which is used some in >> entry code), the stack canary, and the PTI stack (which is defined per >> task). > > Does anything unmap the PTI stack? Mapping is easy, and unmapping > could be a pretty big mess. >
No, there's no unmap. The mapping exists as long as the task page-table does (i.e. as long as the task mm exits). I assume that the task stack and mm are freed at the same time but that's not something I have checked.
alex.
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