Messages in this thread | | | Subject | Re: [RFC PATCH] x86: Make sure verify_cpu has a good stack | From | Mika Penttilä <> | Date | Wed, 2 Mar 2016 17:55:14 +0200 |
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On 02.03.2016 13:20, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > 04633df0c43d ("x86/cpu: Call verify_cpu() after having entered long mode too") > added the call to verify_cpu() for sanitizing CPU configuration. > > The latter uses the stack minimally and it can happen that we land in > startup_64() directly from a 64-bit bootloader. Then we want to use our > own, known good stack. > > Do that. > > APs don't need this as the trampoline sets up a stack for them. > > Reported-by: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > arch/x86/kernel/head_64.S | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > index 22fbf9df61bb..d60a044c2fdc 100644 > --- a/arch/x86/kernel/head_64.S > +++ b/arch/x86/kernel/head_64.S > @@ -64,6 +64,10 @@ startup_64: > * tables and then reload them. > */ > > + /* Setup a stack for verify_cpu */ > + movq stack_start - __START_KERNEL_map, %rsp > + subq $__START_KERNEL_map, %rsp > +
You subtract __START_KERNEL_map twice ?
--Mika
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