On Mon, 2018-01-08 at 16:48 -0800, Linus Torvalds wrote: > On Mon, Jan 8, 2018 at 4:42 PM, David Woodhouse <dw...@infradead.org> wrote: > > > > > > Hm... on a context switch you're reloading the registers that were in > > the other saved context. > > Actually, iirc we used to very actively try to minimize that by having > the inline asm mark a lot of registers as clobbered.
Sure, in that case it makes sense purely as a matter of hygiene to explicitly clear the registers which were marked as clobbered. In the original patch set from that Intel were collecting — before they threw it all out the fucking window and started again from scratch on the day the embargo broke — there were patches to do the same thing on syscall entry too, for precisely the same reason.
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