[xen master] x86/shadow: Don't use signed bitfield in sh_emulate_ctxt

[patchbot@xxxxxxx]

commit 9c0b20700103d746824687383fd330f5da97b72d
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon May 9 11:18:20 2022 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Jun 15 10:51:57 2023 +0100

    x86/shadow: Don't use signed bitfield in sh_emulate_ctxt
    
    '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@xxxxxxxxxx>
    Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 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 d02d70ab07..a0f275251f 100644
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -815,7 +815,7 @@ 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
 };
 
--
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