target/m68k: only change valid bits in CACR

This is used by netBSD (and MacOS ROM) to detect the MMU type

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Thomas Huth <huth@tuxfamily.org>
Message-Id: <20191220172415.35838-1-laurent@vivier.eu>
[lv: add a comment before m680x0_cpu_common()]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

3 files changed, 36 insertions, 9 deletions

diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index e6596de29c..f276335faf 100644
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -114,11 +114,9 @@ static void m68000_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
 
-static void m68020_cpu_initfn(Object *obj)
+/* common features for 68020, 68030 and 68040 */
+static void m680x0_cpu_common(CPUM68KState *env)
 {
-    M68kCPU *cpu = M68K_CPU(obj);
-    CPUM68KState *env = &cpu->env;
-
     m68k_set_feature(env, M68K_FEATURE_M68000);
     m68k_set_feature(env, M68K_FEATURE_USP);
     m68k_set_feature(env, M68K_FEATURE_WORD_INDEX);
@@ -136,14 +134,31 @@ static void m68020_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_CHK2);
     m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
-#define m68030_cpu_initfn m68020_cpu_initfn
+
+static void m68020_cpu_initfn(Object *obj)
+{
+    M68kCPU *cpu = M68K_CPU(obj);
+    CPUM68KState *env = &cpu->env;
+
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_M68020);
+}
+
+static void m68030_cpu_initfn(Object *obj)
+{
+    M68kCPU *cpu = M68K_CPU(obj);
+    CPUM68KState *env = &cpu->env;
+
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_M68030);
+}
 
 static void m68040_cpu_initfn(Object *obj)
 {
     M68kCPU *cpu = M68K_CPU(obj);
     CPUM68KState *env = &cpu->env;
 
-    m68020_cpu_initfn(obj);
+    m680x0_cpu_common(env);
     m68k_set_feature(env, M68K_FEATURE_M68040);
 }
 
@@ -166,6 +181,7 @@ static void m68060_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_BKPT);
     m68k_set_feature(env, M68K_FEATURE_RTD);
     m68k_set_feature(env, M68K_FEATURE_CHK2);
+    m68k_set_feature(env, M68K_FEATURE_M68060);
 }
 
 static void m5208_cpu_initfn(Object *obj)
diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 20de3c379a..11c71fa962 100644
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -460,6 +460,10 @@ void do_m68k_semihosting(CPUM68KState *env, int nr);
 
 enum m68k_features {
     M68K_FEATURE_M68000,
+    M68K_FEATURE_M68020,
+    M68K_FEATURE_M68030,
+    M68K_FEATURE_M68040,
+    M68K_FEATURE_M68060,
     M68K_FEATURE_CF_ISA_A,
     M68K_FEATURE_CF_ISA_B, /* (ISA B or C).  */
     M68K_FEATURE_CF_ISA_APLUSC, /* BIT/BITREV, FF1, STRLDSR (ISA A+ or C).  */
@@ -481,7 +485,6 @@ enum m68k_features {
     M68K_FEATURE_BKPT,
     M68K_FEATURE_RTD,
     M68K_FEATURE_CHK2,
-    M68K_FEATURE_M68040, /* instructions specific to MC68040 */
     M68K_FEATURE_MOVEP,
 };
 
diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index ae766a6cb0..baf7729af0 100644
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -203,9 +203,17 @@ void HELPER(m68k_movec_to)(CPUM68KState *env, uint32_t reg, uint32_t val)
     case M68K_CR_VBR:
         env->vbr = val;
         return;
-    /* MC680[234]0 */
+    /* MC680[2346]0 */
     case M68K_CR_CACR:
-        env->cacr = val;
+        if (m68k_feature(env, M68K_FEATURE_M68020)) {
+            env->cacr = val & 0x0000000f;
+        } else if (m68k_feature(env, M68K_FEATURE_M68030)) {
+            env->cacr = val & 0x00003f1f;
+        } else if (m68k_feature(env, M68K_FEATURE_M68040)) {
+            env->cacr = val & 0x80008000;
+        } else if (m68k_feature(env, M68K_FEATURE_M68060)) {
+            env->cacr = val & 0xf8e0e000;
+        }
         m68k_switch_sp(env);
         return;
     /* MC680[34]0 */