From fe60494b7722ecedbf96cea507b0d37e2abe994e Mon Sep 17 00:00:00 2001
From: Laurent Vivier <laurent@vivier.eu>
Date: Tue, 14 Jan 2020 08:17:06 -0500
Subject: [PATCH] target/m68k: only change valid bits in CACR

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

Backports commit 18b6102e51bb317d25ee61b49b7b56702b79560c from qemu
---
 qemu/target/m68k/cpu.c    | 28 ++++++++++++++++++++++------
 qemu/target/m68k/cpu.h    |  5 ++++-
 qemu/target/m68k/helper.c | 10 +++++++++-
 3 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/qemu/target/m68k/cpu.c b/qemu/target/m68k/cpu.c
index 34794cd8..6993cb5a 100644
--- a/qemu/target/m68k/cpu.c
+++ b/qemu/target/m68k/cpu.c
@@ -110,11 +110,9 @@ static void m68000_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
 
-static void m68020_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
+/* common features for 68020, 68030 and 68040 */
+static void m680x0_cpu_common(CPUM68KState *env)
 {
-    M68kCPU *cpu = M68K_CPU(uc, 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);
@@ -132,14 +130,31 @@ static void m68020_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     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(struct uc_struct *uc, Object *obj, void *opaque)
+{
+    M68kCPU *cpu = M68K_CPU(uc, obj);
+    CPUM68KState *env = &cpu->env;
+
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_M68020);
+}
+
+static void m68030_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
+{
+    M68kCPU *cpu = M68K_CPU(uc, obj);
+    CPUM68KState *env = &cpu->env;
+
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_M68030);
+}
 
 static void m68040_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
 {
     M68kCPU *cpu = M68K_CPU(uc, obj);
     CPUM68KState *env = &cpu->env;
 
-    m68020_cpu_initfn(uc, obj, opaque);
+    m680x0_cpu_common(env);
     m68k_set_feature(env, M68K_FEATURE_M68040);
 }
 
@@ -162,6 +177,7 @@ static void m68060_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     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(struct uc_struct *uc, Object *obj, void *opaque)
diff --git a/qemu/target/m68k/cpu.h b/qemu/target/m68k/cpu.h
index 29d9fbe0..19e67fc4 100644
--- a/qemu/target/m68k/cpu.h
+++ b/qemu/target/m68k/cpu.h
@@ -456,6 +456,10 @@ 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).  */
@@ -477,7 +481,6 @@ 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/qemu/target/m68k/helper.c b/qemu/target/m68k/helper.c
index a6a398b9..301fba89 100644
--- a/qemu/target/m68k/helper.c
+++ b/qemu/target/m68k/helper.c
@@ -68,7 +68,15 @@ void HELPER(m68k_movec_to)(CPUM68KState *env, uint32_t reg, uint32_t val)
         return;
     /* MC680[234]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 */