Re: [PATCH 05/20] x86/uaccess/xen: Suppress SMAP warnings

From: Juergen Gross
Date: Thu Mar 07 2019 - 07:22:59 EST

On 07/03/2019 12:45, 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.

No, this is a hypercall with parameters passed through from user land
(Xen tools). So setting AC=1 is not related to hysterical reasons, but
to indicate that unprivileged buffers are okay here. So please change
the commit message to something like:

Some Xen hypercalls allow parameter buffers in user land, so they need
to set AC=1. Avoid the warning for those cases.

> XXX: arguably we should rename ANNOTATE_NOSPEC_ALTERNATIVE to
> Cc: andrew.cooper3@xxxxxxxxxx
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

Mind Cc-ing the maintainers of the code you are touching in future

With the commit message adjusted:

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>