On Wed, May 25, 2016 at 09:00:49AM -0600, Jan Beulich wrote: > Correct the number of single byte NOPs we want to be replaced in case > neither SMEP nor SMAP are available. > > Also simplify the expression adding these NOPs - at that location . > equals .Lcr4_orig, and removing that part of the expression fixes a > bogus ".space or fill with negative value, ignored" warning by very old > gas (which actually is what made me look at those constructs again). > > Signed-off-by: Jan Beulich <jbeul...@suse.com> > > --- a/xen/arch/x86/x86_64/compat/entry.S > +++ b/xen/arch/x86/x86_64/compat/entry.S > @@ -175,7 +175,7 @@ compat_bad_hypercall: > ENTRY(compat_restore_all_guest) > ASSERT_INTERRUPTS_DISABLED > .Lcr4_orig: > - .skip (.Lcr4_alt_end - .Lcr4_alt) - (. - .Lcr4_orig), 0x90 > + .skip .Lcr4_alt_end - .Lcr4_alt, 0x90 > .Lcr4_orig_end: > .pushsection .altinstr_replacement, "ax" > .Lcr4_alt: > @@ -200,7 +200,8 @@ ENTRY(compat_restore_all_guest) > jne 1b > .Lcr4_alt_end: > .section .altinstructions, "a" > - altinstruction_entry .Lcr4_orig, .Lcr4_orig, X86_FEATURE_ALWAYS, 12, > 0 > + altinstruction_entry .Lcr4_orig, .Lcr4_orig, X86_FEATURE_ALWAYS, \ > + (.Lcr4_orig_end - .Lcr4_orig), 0 > altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMEP, \ > (.Lcr4_orig_end - .Lcr4_orig), \ > (.Lcr4_alt_end - .Lcr4_alt) > > >
FWIW: Reviewed-by: Wei Liu <wei.l...@citrix.com> And subject to review from Andrew: Release-acked-by: Wei Liu <wei.l...@citrix.com> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
