From 8808f9a2afc7eab67b761145c84fc32580c51c2f Mon Sep 17 00:00:00 2001 From: Nicola Vetrini Date: Fri, 2 May 2025 16:35:34 -0700 Subject: [PATCH] x86: x86_emulate: address violations of MISRA C Rule 19.1 Rule 19.1 states: "An object shall not be assigned or copied to an overlapping object". In the function like macro "get_rep_prefix", one member of a union is assigned the value of another member. Reading from one member and writing to the other violates the rule, while not causing Undefined Behavior due to their relative sizes. Instead, use casts combined with exactly overlapping accesses to address violations. No functional change. Signed-off-by: Nicola Vetrini Signed-off-by: Federico Serafini Signed-off-by: Victor Lira Reviewed-by: Stefano Stabellini Acked-by: Andrew Cooper --- xen/arch/x86/x86_emulate/x86_emulate.c | 6 +++--- 1 file changed, 3 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..a588435b5e 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -527,8 +527,8 @@ static inline void put_loop_count( if ( !amd_like(ctxt) && mode_64bit() && ad_bytes == 4 ) \ { \ _regs.r(cx) = 0; \ - if ( extend_si ) _regs.r(si) = _regs.esi; \ - if ( extend_di ) _regs.r(di) = _regs.edi; \ + if ( extend_si ) _regs.r(si) = (uint32_t)_regs.r(si); \ + if ( extend_di ) _regs.r(di) = (uint32_t)_regs.r(di); \ } \ goto complete_insn; \ } \ @@ -2029,7 +2029,7 @@ 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: _regs.r(ax) = (uint32_t)(int16_t)_regs.r(ax); break; /* cwde */ case 8: _regs.r(ax) = (int32_t)_regs.r(ax); break; /* cdqe */ } break;