Messages in this thread | | | Date | Fri, 25 Feb 2022 11:24:36 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 11/39] x86/ibt,kvm: Add ENDBR to fastops |
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On Thu, Feb 24, 2022 at 04:54:04PM -0800, Kees Cook wrote: > On Thu, Feb 24, 2022 at 03:51:49PM +0100, Peter Zijlstra wrote: > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > --- > > arch/x86/kvm/emulate.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > --- a/arch/x86/kvm/emulate.c > > +++ b/arch/x86/kvm/emulate.c > > @@ -189,7 +189,7 @@ > > #define X16(x...) X8(x), X8(x) > > > > #define NR_FASTOP (ilog2(sizeof(ulong)) + 1) > > -#define FASTOP_SIZE 8 > > +#define FASTOP_SIZE (8 * (1 + HAS_KERNEL_IBT)) > > Err, is this right? FASTOP_SIZE is used both as a size and an alignment. > But the ENDBR instruction is 4 bytes? Commit log maybe needed to > describe this.
Note how that comes out as 8*1 or 8*2, iow 8 or 16. Does that clarify? That is, 8+4 being 12 is ovbiuosly a fail for alignment.
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