Messages in this thread | | | Date | Mon, 27 Nov 2017 18:33:39 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH 02/24] x86/mm/kaiser: Prepare the x86/entry assembly code for entry/exit CR3 switching |
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On Mon, 27 Nov 2017, Peter Zijlstra wrote: > On Mon, Nov 27, 2017 at 11:49:01AM +0100, Ingo Molnar wrote: > > diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S > > index caf74a1bb3de..df0152bee8a8 100644 > > > @@ -198,6 +201,14 @@ ENTRY(entry_SYSCALL_64) > > > > swapgs > > movq %rsp, PER_CPU_VAR(rsp_scratch) > > + > > + /* > > + * The kernel CR3 is needed to map the process stack, but we > > + * need a scratch register to be able to load CR3. %rsp is > > + * clobberable right now, so use it as a scratch register. > > + * %rsp will look crazy here for a couple instructions. > > + */ > > + SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp > > movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp > > > > /* Construct struct pt_regs on stack */ > > I think we can do away with this one, on account of never getting here > because of entry_SYSCALL_64_trampoline.
It's on my list already. About 5 people noticed :)
Still trying to decode that paravirt fail.....
Thanks,
tglx
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