monitor,diff-test: check eflags

include/cpu/exec.h

@@ -2,6 +2,7 @@
 #define __CPU_EXEC_H__
 
 #include "nemu.h"
+#include "monitor/diff-test.h"
 
 #define make_EHelper(name) void concat(exec_, name) (vaddr_t *eip)
 typedef void (*EHelper) (vaddr_t *);

include/cpu/reg.h

@@ -8,6 +8,22 @@ enum { R_EAX, R_ECX, R_EDX, R_EBX, R_ESP, R_EBP, R_ESI, R_EDI };
 enum { R_AX, R_CX, R_DX, R_BX, R_SP, R_BP, R_SI, R_DI };
 enum { R_AL, R_CL, R_DL, R_BL, R_AH, R_CH, R_DH, R_BH };
 
+#define EFLAGS_BIT_CF 0
+#define EFLAGS_BIT_ZF 6
+#define EFLAGS_BIT_SF 7
+#define EFLAGS_BIT_IF 9
+#define EFLAGS_BIT_OF 11
+
+#define __map_eflags(f) f(OF) f(IF) f(SF) f(ZF) f(CF)
+#define __f(X) concat(EFLAGS_MASK_, X) = 1 << concat(EFLAGS_BIT_, X),
+enum {
+  __map_eflags(__f)
+#undef __f
+#define __f(X) | concat(EFLAGS_MASK_, X)
+  EFLAGS_MASK_ALL = 0 __map_eflags(__f)
+#undef __f
+};
+
 /* TODO: Re-organize the `CPU_state' structure to match the register
  * encoding scheme in i386 instruction format. For example, if we
  * access cpu.gpr[3]._16, we will get the `bx' register; if we access
@@ -34,6 +50,7 @@ typedef struct {
   };
 
   vaddr_t eip;
+  uint32_t eflags;
   uint16_t cs;
 
   rtlreg_t OF, CF, SF, ZF, IF;

src/monitor/diff-test/diff-test.h → include/monitor/diff-test.h

@@ -3,4 +3,8 @@
 
 #define DIFFTEST_REG_SIZE (sizeof(uint32_t) * 9) // GRPs + EIP
 
+void difftest_skip_ref(void);
+void difftest_skip_dut(void);
+void difftest_skip_eflags(uint32_t mask);
+
 #endif

src/cpu/exec/arith.c

@@ -140,6 +140,7 @@ make_EHelper(mul) {
     default: assert(0);
   }
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template1(mul);
 }
 
@@ -165,6 +166,7 @@ make_EHelper(imul1) {
     default: assert(0);
   }
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template1(imul);
 }
 
@@ -176,6 +178,7 @@ make_EHelper(imul2) {
   rtl_imul_lo(&t2, &t1, &t0);
   operand_write(id_dest, &t2);
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template2(imul);
 }
 
@@ -188,6 +191,7 @@ make_EHelper(imul3) {
   rtl_imul_lo(&t2, &t1, &t0);
   operand_write(id_dest, &t2);
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template3(imul);
 }
 
@@ -219,6 +223,7 @@ make_EHelper(div) {
     default: assert(0);
   }
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template1(div);
 }
 
@@ -250,5 +255,6 @@ make_EHelper(idiv) {
     default: assert(0);
   }
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template1(idiv);
 }

src/cpu/exec/eflags.c

@@ -2,37 +2,24 @@
 
 void rtl_compute_eflags(rtlreg_t *dest) {
   rtl_li(dest, 0);
-  rtl_shli(&at, &cpu.OF, 11);
-  rtl_or(dest, dest, &at);
 
-  rtl_shli(&at, &cpu.IF, 9);
+#define __f(X) \
+  rtl_shli(&at, &cpu.X, concat(EFLAGS_BIT_, X)); \
   rtl_or(dest, dest, &at);
 
-  rtl_shli(&at, &cpu.SF, 7);
-  rtl_or(dest, dest, &at);
+  __map_eflags(__f)
 
-  rtl_shli(&at, &cpu.ZF, 6);
-  rtl_or(dest, dest, &at);
-
-  rtl_shli(&at, &cpu.CF, 0);
-  rtl_or(dest, dest, &at);
+#undef __f
 
   rtl_ori(dest, dest, 0x2);
 }
 
 void rtl_set_eflags(const rtlreg_t *src) {
-  rtl_shri(&at, src, 11);
-  rtl_andi(&cpu.OF, &at, 0x1);
-
-  rtl_shri(&at, src, 9);
-  rtl_andi(&cpu.IF, &at, 0x1);
-
-  rtl_shri(&at, src, 7);
-  rtl_andi(&cpu.SF, &at, 0x1);
+#define __f(X) \
+  rtl_shri(&at, src, concat(EFLAGS_BIT_, X)); \
+  rtl_andi(&cpu.X, &at, 0x1);
 
-  rtl_shri(&at, src, 6);
-  rtl_andi(&cpu.ZF, &at, 0x1);
+  __map_eflags(__f)
 
-  rtl_shri(&at, src, 0);
-  rtl_andi(&cpu.CF, &at, 0x1);
+#undef __f
 }

src/cpu/exec/logic.c

@@ -44,6 +44,7 @@ make_EHelper(sar) {
   operand_write(id_dest, &t2);
   rtl_update_ZFSF(&t2, id_dest->width);
   // unnecessary to update CF and OF in NEMU
+  difftest_skip_eflags(EFLAGS_MASK_CF | EFLAGS_MASK_OF);
   print_asm_template2(sar);
 }
 
@@ -52,6 +53,7 @@ make_EHelper(shl) {
   operand_write(id_dest, &t2);
   rtl_update_ZFSF(&t2, id_dest->width);
   // unnecessary to update CF and OF in NEMU
+  difftest_skip_eflags(EFLAGS_MASK_CF | EFLAGS_MASK_OF);
   print_asm_template2(shl);
 }
 
@@ -60,6 +62,7 @@ make_EHelper(shr) {
   operand_write(id_dest, &t2);
   rtl_update_ZFSF(&t2, id_dest->width);
   // unnecessary to update CF and OF in NEMU
+  difftest_skip_eflags(EFLAGS_MASK_CF | EFLAGS_MASK_OF);
   print_asm_template2(shr);
 }
 
@@ -71,8 +74,8 @@ make_EHelper(rol) {
   rtl_or(&t2, &t1, &t2);
 
   operand_write(id_dest, &t2);
-  rtl_update_ZFSF(&t2, id_dest->width);
-  // unnecessary to update CF and OF in NEMU
+  // unnecessary to update eflags in NEMU
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
   print_asm_template2(rol);
 }
 
@@ -104,6 +107,7 @@ make_EHelper(shld) {
   operand_write(id_dest, &t2);
   rtl_update_ZFSF(&t2, id_dest->width);
   // unnecessary to update CF and OF in NEMU
+  difftest_skip_eflags(EFLAGS_MASK_CF | EFLAGS_MASK_OF);
   print_asm_template3(shld);
 }
 
@@ -119,5 +123,6 @@ make_EHelper(shrd) {
   operand_write(id_dest, &t2);
   rtl_update_ZFSF(&t2, id_dest->width);
   // unnecessary to update CF and OF in NEMU
+  difftest_skip_eflags(EFLAGS_MASK_CF | EFLAGS_MASK_OF);
   print_asm_template3(shrd);
 }

src/cpu/exec/special.c

@@ -38,7 +38,6 @@ make_EHelper(inv) {
 
 make_EHelper(nemu_trap) {
 #if defined(DIFF_TEST)
-  void difftest_skip_ref();
   difftest_skip_ref();
 #endif
 

src/cpu/exec/system.c

 #include "cpu/exec.h"
 
-void difftest_skip_ref();
-void difftest_skip_dut();
-
 make_EHelper(lidt) {
   cpu.idtr.limit = vaddr_read(id_dest->addr, 2);
   cpu.idtr.base = vaddr_read(id_dest->addr + 2, 4);
@@ -52,6 +49,8 @@ make_EHelper(iret) {
 
   rtl_jr(&t0);
 
+  difftest_skip_eflags(EFLAGS_MASK_ALL);
+
   print_asm("iret");
 }
 

src/monitor/diff-test/diff-test.c

@@ -2,7 +2,7 @@
 
 #include "nemu.h"
 #include "monitor/monitor.h"
-#include "diff-test.h"
+#include "monitor/diff-test.h"
 
 static void (*ref_difftest_memcpy_from_dut)(paddr_t dest, void *src, size_t n);
 static void (*ref_difftest_getregs)(void *c);
@@ -11,9 +11,11 @@ static void (*ref_difftest_exec)(uint64_t n);
 
 static bool is_skip_ref;
 static bool is_skip_dut;
+static uint32_t eflags_skip_mask;
 
 void difftest_skip_ref() { is_skip_ref = true; }
 void difftest_skip_dut() { is_skip_dut = true; }
+void difftest_skip_eflags(uint32_t mask) { eflags_skip_mask = mask; }
 
 void init_difftest(char *ref_so_file, long img_size) {
 #ifndef DIFF_TEST
@@ -57,6 +59,22 @@ void init_difftest(char *ref_so_file, long img_size) {
         str(r), eip, regs.r, cpu.r); \
   }
 
+#define check_flag(regs, f) \
+  do { \
+    uint32_t mask = concat(EFLAGS_MASK_, f); \
+    uint32_t __flag = ((regs.eflags & mask) != 0); \
+    if (mask & eflags_skip_mask) { \
+      cpu.f = __flag; \
+    } \
+    else { \
+      if (__flag != cpu.f) { \
+        Log("%s is different after executing instruction at eip = 0x%08x, right = 0x%08x, wrong = 0x%08x", \
+            "eflags." str(f), eip, __flag, cpu.f); \
+        nemu_state = NEMU_ABORT; \
+      } \
+    } \
+  } while(0)
+
 void difftest_step(uint32_t eip) {
   CPU_state ref_r;
 
@@ -67,6 +85,8 @@ void difftest_step(uint32_t eip) {
 
   if (is_skip_ref) {
     // to skip the checking of an instruction, just copy the reg state to reference design
+    ref_difftest_getregs(&ref_r);
+    cpu.eflags = ref_r.eflags;
     ref_difftest_setregs(&cpu);
     is_skip_ref = false;
     return;
@@ -91,4 +111,13 @@ void difftest_step(uint32_t eip) {
 
     nemu_state = NEMU_ABORT;
   }
+
+  check_flag(ref_r, CF);
+  check_flag(ref_r, OF);
+  check_flag(ref_r, SF);
+  check_flag(ref_r, ZF);
+
+  if (eflags_skip_mask) {
+    eflags_skip_mask = 0;
+  }
 }

src/monitor/diff-test/ref.c

 #include "nemu.h"
-#include "diff-test.h"
+#include "monitor/diff-test.h"
 
 void cpu_exec(uint64_t);
 

tools/qemu-diff/src/diff-test.c

@@ -3,7 +3,7 @@
 #include <signal.h>
 
 typedef uint32_t paddr_t;
-#define DIFFTEST_REG_SIZE (sizeof(uint32_t) * 9) // GPRs + EIP
+#define DIFFTEST_REG_SIZE (sizeof(uint32_t) * 10) // GPRs + EIP + EFLAGS
 
 bool gdb_connect_qemu(void);
 bool gdb_memcpy_to_qemu(uint32_t, void *, int);
@@ -113,9 +113,6 @@ void difftest_init(void) {
     assert(ok == 1);
 
     // execute enough instructions to enter protected mode
-    int i;
-    for (i = 0; i < 20; i ++) {
-      gdb_si();
-    }
+    difftest_exec(20);
   }
 }