On Wed, Jul 13, 2022 at 06:22:41PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 13, 2022 at 08:24:37AM -0700, Nathan Chancellor wrote:
> > Clang warns:
> >
> > arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection]
> > DEFINE_PER_CPU(u64, x86_spec_ctrl_current);
> > ^
> > arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here
> > extern u64 x86_spec_ctrl_current;
> > ^
> > 1 error generated.
> >
> > The declaration should be using DECLARE_PER_CPU instead so all
> > attributes stay in sync.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS")
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> > ---
> >
> > v1 -> v2: https://lore.kernel.org/20220713152222.1697913-1-nathan@xxxxxxxxxx/
> >
> > * Use asm/percpu.h instead of linux/percpu.h to avoid static call
> > include errors.
> >
> > arch/x86/include/asm/nospec-branch.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
> > index bb05ed4f46bd..10a3bfc1eb23 100644
> > --- a/arch/x86/include/asm/nospec-branch.h
> > +++ b/arch/x86/include/asm/nospec-branch.h
> > @@ -11,6 +11,7 @@
> > #include <asm/cpufeatures.h>
> > #include <asm/msr-index.h>
> > #include <asm/unwind_hints.h>
> > +#include <asm/percpu.h>
> >
> > #define RETPOLINE_THUNK_SIZE 32
> >
>
> When I tried this earlier today I ran into cyclic headers, you sure this
> works?
Yes, I did my regular set of x86 builds with clang and they all passed.
Cheers,
Nathan
