From: Nicola Vetrini <nicola.vetr...@bugseng.com>
Rule 19.1 states: "An object shall not be assigned or copied
to an overlapping object". Since the "call" and "compat_call" are
fields of the same union, reading from one member and writing to
the other violates the rule, while not causing Undefined Behavior
due to their relative sizes. However, a dummy variables are used to
address the violations and prevent the future possibility of
incurring in UB.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetr...@bugseng.com>
Signed-off-by: Federico Serafini <federico.seraf...@bugseng.com>
Signed-off-by: Victor Lira <victorm.l...@amd.com>
---
Cc: Andrew Cooper <andrew.coop...@citrix.com>
Cc: Anthony PERARD <anthony.per...@vates.tech>
Cc: Michal Orzel <michal.or...@amd.com>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Julien Grall <jul...@xen.org>
Cc: Roger Pau Monné <roger....@citrix.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Nicola Vetrini <nicola.vetr...@bugseng.com>
Cc: Federico Serafini <federico.seraf...@bugseng.com>
Cc: Bertrand Marquis <bertrand.marq...@arm.com>
---
xen/arch/x86/x86_emulate/x86_emulate.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 8e14ebb35b..44dc3039f3 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -526,9 +526,19 @@ static inline void put_loop_count(
*/ \
if ( !amd_like(ctxt) && mode_64bit() && ad_bytes == 4 ) \
{ \
+ uint64_t tmp; \
+ \
_regs.r(cx) = 0; \
- if ( extend_si ) _regs.r(si) = _regs.esi; \
- if ( extend_di ) _regs.r(di) = _regs.edi; \
+ if ( extend_si ) \
+ { \
+ tmp = _regs.esi; \
+ _regs.r(si) = tmp; \
+ } \
+ if ( extend_di ) \
+ { \
+ tmp = _regs.edi; \
+ _regs.r(di) = tmp; \
+ } \
} \
goto complete_insn; \
} \
@@ -2029,7 +2039,12 @@ x86_emulate(
switch ( op_bytes )
{
case 2: _regs.ax = (int8_t)_regs.ax; break; /* cbw */
- case 4: _regs.r(ax) = (uint32_t)(int16_t)_regs.ax; break; /* cwde */
+ case 4:
+ {
+ uint32_t tmp = (uint32_t)(int16_t)_regs.ax;
+ _regs.r(ax) = tmp;
+ break; /* cwde */
+ }
case 8: _regs.r(ax) = (int32_t)_regs.r(ax); break; /* cdqe */
}
break;
--
2.47.0
