| Date | Fri, 8 Mar 2019 13:00:38 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH 05/20] x86/uaccess/xen: Suppress SMAP warnings |
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On Thu, Mar 07, 2019 at 12:45:16PM +0100, Peter Zijlstra wrote: > drivers/xen/privcmd.o: warning: objtool: privcmd_ioctl()+0x1414: call to hypercall_page() with UACCESS enabled > > Xen needs to do HV calls with AC=1 for hysterical raisins. Make the > warning go away. > > XXX: arguably we should rename ANNOTATE_NOSPEC_ALTERNATIVE to > ANNOTATE_IGNORE_ALTERNATIVE. > > Cc: andrew.cooper3@citrix.com > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > arch/x86/include/asm/xen/hypercall.h | 26 ++++++++++++++++++++++---- > 1 file changed, 22 insertions(+), 4 deletions(-) > > --- a/arch/x86/include/asm/xen/hypercall.h > +++ b/arch/x86/include/asm/xen/hypercall.h > @@ -214,6 +214,24 @@ xen_single_call(unsigned int call, > return (long)__res; > } > > +static __always_inline void __xen_stac(void) > +{ > + /* > + * This is just about as horrible as this interface; we abuse the > + * nospec alternative annotation to supress objtool seeing the > + * STAC/CLAC and getting confused about it calling random code with > + * AC=1. > + */ > + asm volatile(ANNOTATE_NOSPEC_ALTERNATIVE > + ASM_STAC ::: "memory", "flags"); > +} > + > +static __always_inline void __xen_clac(void) > +{ > + asm volatile(ANNOTATE_NOSPEC_ALTERNATIVE > + ASM_CLAC ::: "memory", "flags"); > +} > +
Shouldn't these be using SMAP-based alternatives like stac()/clac() do?
-- Josh
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