lkml.org 
[lkml]   [2023]   [Oct]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/6] x86/entry_64: Add VERW just before userspace transition
On Fri, Oct 20, 2023 at 01:45:03PM -0700, Pawan Gupta wrote:
> + /* Mitigate CPU data sampling attacks .e.g. MDS */
> + USER_CLEAR_CPU_BUFFERS
> +
> jmp .Lnative_iret
>
>
> @@ -774,6 +780,9 @@ native_irq_return_ldt:
> */
> popq %rax /* Restore user RAX */
>
> + /* Mitigate CPU data sampling attacks .e.g. MDS */
> + USER_CLEAR_CPU_BUFFERS
> +

I'm thinking the comments add unnecessary noise here. The macro name is
self-documenting enough.

The detail about what mitigations are being done can go above the macro
definition itself, which the reader can refer to if they want more
detail about what the macro is doing and why.

Speaking of the macro name, I think just "CLEAR_CPU_BUFFERS" is
sufficient. The "USER_" prefix makes it harder to read IMO.

--
Josh

\
 
 \ /
  Last update: 2023-10-23 20:22    [W:0.263 / U:0.300 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site