add pushfd, popfd, bt, cpuid

runtime/src/ops/misc.rs

@@ -12,6 +12,22 @@ impl Context {
             .write::<u16>(segofs(self.cpu.regs.ss, self.cpu.regs.get_sp()), x);
     }
 
+    /// cpuid, describing a plain Pentium: an FPU and nothing else (no TSC, no
+    /// MMX), so programs take the paths this runtime implements.
+    pub fn cpuid(&mut self) {
+        let (eax, ebx, ecx, edx) = match self.cpu.regs.eax {
+            // Highest leaf, and "GenuineIntel" in ebx:edx:ecx.
+            0 => (1, 0x756e_6547, 0x6c65_746e, 0x4965_6e69),
+            // Family 5 model 4 stepping 3; feature flags: FPU.
+            1 => (0x543, 0, 0, 0x1),
+            _ => (0, 0, 0, 0),
+        };
+        self.cpu.regs.eax = eax;
+        self.cpu.regs.ebx = ebx;
+        self.cpu.regs.ecx = ecx;
+        self.cpu.regs.edx = edx;
+    }
+
     pub fn pop32(&mut self) -> u32 {
         let x = self.memory.read::<u32>(self.cpu.regs.esp);
         self.cpu.regs.esp += 4;

tc/src/codegen/misc.rs

@@ -93,7 +93,37 @@ impl<'a> CodeGen<'a> {
                     self.todo(format!("int {:#x}", instr.immediate8()));
                 }
             }
-            Int3 | Cmpxchg | Pushfd | Cpuid | Xgetbv | Bt | Div => self.todo(instr_name(instr)),
+            Int3 | Cmpxchg | Xgetbv | Div => self.todo(instr_name(instr)),
+
+            Cpuid => self.line("ctx.cpuid();"),
+
+            Bt => {
+                // With a memory operand and a register index the hardware can
+                // address bits outside the operand; only handle the in-range forms.
+                if instr.op0_kind() == iced_x86::OpKind::Memory
+                    && instr.op1_kind() == iced_x86::OpKind::Register
+                {
+                    self.todo(format!("{instr}"));
+                    return true;
+                }
+                let size = op_size(instr, 0);
+                self.line(format!(
+                    "let bit = ({} as u32) % {size};",
+                    self.get_op(instr, 1)
+                ));
+                self.line(format!(
+                    "ctx.cpu.flags.set(Flags::CF, ({} >> bit) & 1 != 0);",
+                    self.get_op(instr, 0)
+                ));
+            }
+
+            Pushfd => self.line("ctx.push32(ctx.cpu.flags.bits());"),
+            Popfd => {
+                // Keep bits we don't model (like ID, bit 21) so that the usual
+                // "can I toggle ID?" probe for cpuid support sees them again.
+                self.line("let flags = ctx.pop32();");
+                self.line("ctx.cpu.flags = Flags::from_bits_retain(flags);");
+            }
 
             // CBW/CWDE: sign extend to next larger ax
             Cbw => self.line("ctx.cpu.regs.set_ax(ctx.cpu.regs.get_al() as i8 as i16 as u16);"),