| From | Jürgen Groß <> | Subject | Re: [PATCH 15/21] x86/xen/pvh: Convert indirect jump to retpoline | Date | Fri, 15 Jan 2021 06:24:10 +0100 |
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On 14.01.21 20:40, Josh Poimboeuf wrote: > It's kernel policy to not have (unannotated) indirect jumps because of > Spectre v2. This one's probably harmless, but better safe than sorry. > Convert it to a retpoline. > > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: Juergen Gross <jgross@suse.com> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > arch/x86/platform/pvh/head.S | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S > index 43b4d864817e..d87cebd08d32 100644 > --- a/arch/x86/platform/pvh/head.S > +++ b/arch/x86/platform/pvh/head.S > @@ -16,6 +16,7 @@ > #include <asm/boot.h> > #include <asm/processor-flags.h> > #include <asm/msr.h> > +#include <asm/nospec-branch.h> > #include <xen/interface/elfnote.h> > > __HEAD > @@ -105,7 +106,7 @@ SYM_CODE_START_LOCAL(pvh_start_xen) > /* startup_64 expects boot_params in %rsi. */ > mov $_pa(pvh_bootparams), %rsi > mov $_pa(startup_64), %rax > - jmp *%rax > + JMP_NOSPEC rax
I'd rather have it annotated only.
Using ALTERNATIVE in very early boot code is just adding needless clutter, as the retpoline variant won't ever be active.
Juergen [unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] |