target/m68k: Fix exception frame format for 68010

From the 68010 a word with the frame format and exception vector
are placed on the stack before the PC and SR.

M68K_FEATURE_QUAD_MULDIV is currently checked to workout if to do
this or not for the configured CPU but that flag isn't set for
68010 so currently the exception stack when 68010 is configured
is incorrect.

It seems like checking M68K_FEATURE_MOVEFROMSR_PRIV would do but
adding a new flag that shows exactly what is going on here is
maybe clearer.

Add a new flag for the behaviour, M68K_FEATURE_EXCEPTION_FORMAT_VEC,
and set it for 68010 and above, and then use it to control if the
format and vector word are pushed/pop during exception entry/exit.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2164
Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Message-ID: <20240115101643.2165387-1-daniel@0x0f.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index 8a8392e6945b0824526e2beabf1a5c5079bf3191..d5a71c63152bcd559b24a4c19cb4bf36b66d4190 100644 (file)
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -142,7 +142,8 @@ static void m68000_cpu_initfn(Object *obj)
 }
 
 /*
- * Adds BKPT, MOVE-from-SR *now priv instr, and MOVEC, MOVES, RTD
+ * Adds BKPT, MOVE-from-SR *now priv instr, and MOVEC, MOVES, RTD,
+ *      format+vector in exception frame.
  */
 static void m68010_cpu_initfn(Object *obj)
 {
@@ -155,6 +156,7 @@ static void m68010_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_BKPT);
     m68k_set_feature(env, M68K_FEATURE_MOVEC);
     m68k_set_feature(env, M68K_FEATURE_MOVEFROMSR_PRIV);
+    m68k_set_feature(env, M68K_FEATURE_EXCEPTION_FORMAT_VEC);
 }
 
 /*

diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 646cacbdf164245228a26d3449ef6169d0e30af6..346427e144201867269a516009d74c219292ea4a 100644 (file)
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -550,6 +550,8 @@ enum m68k_features {
     M68K_FEATURE_TRAPCC,
     /* MOVE from SR privileged (from 68010) */
     M68K_FEATURE_MOVEFROMSR_PRIV,
+    /* Exception frame with format+vector (from 68010) */
+    M68K_FEATURE_EXCEPTION_FORMAT_VEC,
 };
 
 static inline bool m68k_feature(CPUM68KState *env, int feature)

diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c
index 47b4173bb97b56fffe5172ec2c1d00739dea73e8..956e76eb5f3f55479ae7f7e6001b5ddbab210679 100644 (file)
--- a/target/m68k/op_helper.c
+++ b/target/m68k/op_helper.c
@@ -52,7 +52,7 @@ throwaway:
     sp += 2;
     env->pc = cpu_ldl_mmuidx_ra(env, sp, MMU_KERNEL_IDX, 0);
     sp += 4;
-    if (m68k_feature(env, M68K_FEATURE_QUAD_MULDIV)) {
+    if (m68k_feature(env, M68K_FEATURE_EXCEPTION_FORMAT_VEC)) {
         /*  all except 68000 */
         fmt = cpu_lduw_mmuidx_ra(env, sp, MMU_KERNEL_IDX, 0);
         sp += 2;
@@ -256,7 +256,7 @@ static inline void do_stack_frame(CPUM68KState *env, uint32_t *sp,
                                   uint16_t format, uint16_t sr,
                                   uint32_t addr, uint32_t retaddr)
 {
-    if (m68k_feature(env, M68K_FEATURE_QUAD_MULDIV)) {
+    if (m68k_feature(env, M68K_FEATURE_EXCEPTION_FORMAT_VEC)) {
         /*  all except 68000 */
         CPUState *cs = env_cpu(env);
         switch (format) {