[PATCH 2/3] x86/shadow: Don't use signed bitfield in sh_emulate_ctxt

[Andrew Cooper <andrew.cooper3@citrix.com>]

'int' bitfields in particular have implementation defined behaviour under gcc
and can change signed-ness with -funsigned-bitfields.

There is no need for low_bit_was_clear to be a bitfield in the first place; it
is only used as a boolean.  Doing so even improves the code generation in
sh_emulate_map_dest() to avoid emitting a merge with structure padding.

Spotted by Eclair MISRA scanner.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien@xen.org>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
CC: Bertrand Marquis <bertrand.marquis@arm.com>
---
 xen/arch/x86/mm/shadow/private.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/shadow/private.h b/xen/arch/x86/mm/shadow/private.h
index 3dc024e30f20..772521b55dd3 100644
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -827,7 +827,7 @@ struct sh_emulate_ctxt {
 #if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
     /* Special case for avoiding having to verify writes: remember
      * whether the old value had its low bit (_PAGE_PRESENT) clear. */
-    int low_bit_was_clear:1;
+    bool low_bit_was_clear;
 #endif
 };
 
-- 
2.11.0