lkml.org 
[lkml]   [2021]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 15/21] x86/xen/pvh: Convert indirect jump to retpoline
Date
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]
\
 
 \ /
  Last update: 2021-01-15 06:26    [W:0.346 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site