Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 23 Jul 2015 09:04:38 -0700 | Subject | Re: [PATCH 2/5] x86/entry/64, entry: Set up a valid sysenter stack and prepare for 32-bit merge |
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On Thu, Jul 23, 2015 at 9:01 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > On Thu, 23 Jul 2015 08:31:40 -0700 > Andy Lutomirski <luto@kernel.org> wrote: > >> Oddly, 64-bit kernels already allocate a percpu sysenter stack, but >> they don't enable it. Enable the stack and tweak the rest of the >> sysenter setup code to be similar to the 32-bit version. > > I'm curious. Did you do any investigation into the 64bit code to why it > wasn't set? Do you know if that was just overlooked with some of the > merging between i386 and x86_64 systems? > > I'm not asking you to do it if you have not, but if you have, I think > it would be more comforting to know that it was just overlooked than > there being some other subtle reason.
I think it's just that it was never necessary. #DB has always used IST on x86_64 (IIRC it was like that in the very first commit), so the sysenter stack was never actually referenced.
--Andy
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