target/arm: fix exception syndrome for AArch32 bkpt insn

Debug exceptions that target AArch32 Hyp mode are reported differently
than on AAarch64. Internally, Qemu uses the AArch64 syndromes. Therefore
such exceptions need to be either converted to a prefetch abort
(breakpoints, vector catch) or a data abort (watchpoints).

Cc: qemu-stable@nongnu.org
Signed-off-by: Jan Klötzke <jan.kloetzke@kernkonzept.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240127202758.3326381-1-jan.kloetzke@kernkonzept.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/helper.c

@@ -11015,6 +11015,24 @@ static void arm_cpu_do_interrupt_aarch32(CPUState *cs)
     }
 
     if (env->exception.target_el == 2) {
+        /* Debug exceptions are reported differently on AArch32 */
+        switch (syn_get_ec(env->exception.syndrome)) {
+        case EC_BREAKPOINT:
+        case EC_BREAKPOINT_SAME_EL:
+        case EC_AA32_BKPT:
+        case EC_VECTORCATCH:
+            env->exception.syndrome = syn_insn_abort(arm_current_el(env) == 2,
+                                                     0, 0, 0x22);
+            break;
+        case EC_WATCHPOINT:
+            env->exception.syndrome = syn_set_ec(env->exception.syndrome,
+                                                 EC_DATAABORT);
+            break;
+        case EC_WATCHPOINT_SAME_EL:
+            env->exception.syndrome = syn_set_ec(env->exception.syndrome,
+                                                 EC_DATAABORT_SAME_EL);
+            break;
+        }
         arm_cpu_do_interrupt_aarch32_hyp(cs);
         return;
     }

target/arm/syndrome.h

@@ -25,6 +25,8 @@
 #ifndef TARGET_ARM_SYNDROME_H
 #define TARGET_ARM_SYNDROME_H
 
+#include "qemu/bitops.h"
+
 /* Valid Syndrome Register EC field values */
 enum arm_exception_class {
     EC_UNCATEGORIZED          = 0x00,
@@ -80,6 +82,7 @@ typedef enum {
     SME_ET_InactiveZA,
 } SMEExceptionType;
 
+#define ARM_EL_EC_LENGTH 6
 #define ARM_EL_EC_SHIFT 26
 #define ARM_EL_IL_SHIFT 25
 #define ARM_EL_ISV_SHIFT 24
@@ -94,6 +97,11 @@ static inline uint32_t syn_get_ec(uint32_t syn)
     return syn >> ARM_EL_EC_SHIFT;
 }
 
+static inline uint32_t syn_set_ec(uint32_t syn, uint32_t ec)
+{
+    return deposit32(syn, ARM_EL_EC_SHIFT, ARM_EL_EC_LENGTH, ec);
+}
+
 /*
  * Utility functions for constructing various kinds of syndrome value.
  * Note that in general we follow the AArch64 syndrome values; in a