Re: [XEN PATCH 1/2] xen: apply deviation for Rule 8.4 (asm-only definitions)

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 4 Sep 2023, Nicola Vetrini wrote:
> > Further in the cover letter you say "Deviating variables needs more care,
> > and
> > is therefore postponed to another patch", yet then here you annotate a
> > couple
> > of variables as well. Could you clarify what the criteria are for "needs
> > more
> > care"?
> > 
> 
> I see. I did not intend for those changes to end up in this patch, although
> those two are
> clearly only used by asm code and therefore are excepted.

I reviewed the patch checking that every function and variable is
actually only called/used from asm. Everything checks out, so:

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

However, I think we should drop the change below (could be done on
commit) because it doesn't make sense to add SAF-1-safe for l1_fixmap_x
but not for l1_fixmap.  l1_fixmap has a declaration in
xen/arch/x86/include/asm/page.h but it is not actually used.

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 28fdf820ef3b..828786932021 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -143,6 +143,7 @@
 /* Mapping of the fixmap space needed early. */
 l1_pgentry_t __section(".bss.page_aligned") __aligned(PAGE_SIZE)
     l1_fixmap[L1_PAGETABLE_ENTRIES];
+/* SAF-1-safe */
 l1_pgentry_t __section(".bss.page_aligned") __aligned(PAGE_SIZE)
     l1_fixmap_x[L1_PAGETABLE_ENTRIES];