[PULL,08/13] arm: Correctly handle watchpoints for BE32 CPUs

diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index ca4d0fb..45bcf21 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -132,6 +132,8 @@  struct TranslationBlock;
  * @cpu_exec_exit: Callback for cpu_exec cleanup.
  * @cpu_exec_interrupt: Callback for processing interrupts in cpu_exec.
  * @disas_set_info: Setup architecture specific components of disassembly info
+ * @adjust_watchpoint_address: Perform a target-specific adjustment to an
+ * address before attempting to match it against watchpoints.
  *
  * Represents a CPU family or model.
  */
@@ -195,6 +197,7 @@  typedef struct CPUClass {
     bool (*cpu_exec_interrupt)(CPUState *cpu, int interrupt_request);
 
     void (*disas_set_info)(CPUState *cpu, disassemble_info *info);
+    vaddr (*adjust_watchpoint_address)(CPUState *cpu, vaddr addr, int len);
 } CPUClass;
 
 #ifdef HOST_WORDS_BIGENDIAN
diff --git a/target/arm/internals.h b/target/arm/internals.h
index 2e65bc1..f742a41 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -444,6 +444,11 @@  void hw_breakpoint_update_all(ARMCPU *cpu);
 /* Callback function for checking if a watchpoint should trigger. */
 bool arm_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp);
 
+/* Adjust addresses (in BE32 mode) before testing against watchpoint
+ * addresses.
+ */
+vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len);
+
 /* Callback function for when a watchpoint or breakpoint triggers. */
 void arm_debug_excp_handler(CPUState *cs);
 
diff --git a/exec.c b/exec.c
index 8b9ed73..6fa337b 100644
--- a/exec.c
+++ b/exec.c
@@ -2115,6 +2115,7 @@  static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags)
         return;
     }
     vaddr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset;
+    vaddr = cc->adjust_watchpoint_address(cpu, vaddr, len);
     QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
         if (cpu_watchpoint_address_matches(wp, vaddr, len)
             && (wp->flags & flags)) {
diff --git a/qom/cpu.c b/qom/cpu.c
index d57faf3..0e19b1a 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -391,6 +391,11 @@  static int64_t cpu_common_get_arch_id(CPUState *cpu)
     return cpu->cpu_index;
 }
 
+static vaddr cpu_adjust_watchpoint_address(CPUState *cpu, vaddr addr, int len)
+{
+    return addr;
+}
+
 static void cpu_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -415,6 +420,7 @@  static void cpu_class_init(ObjectClass *klass, void *data)
     k->cpu_exec_enter = cpu_common_noop;
     k->cpu_exec_exit = cpu_common_noop;
     k->cpu_exec_interrupt = cpu_common_exec_interrupt;
+    k->adjust_watchpoint_address = cpu_adjust_watchpoint_address;
     set_bit(DEVICE_CATEGORY_CPU, dc->categories);
     dc->realize = cpu_common_realizefn;
     dc->unrealize = cpu_common_unrealizefn;
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 81448ca..4ee250c 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1675,6 +1675,9 @@  static void arm_cpu_class_init(ObjectClass *oc, void *data)
     cc->gdb_stop_before_watchpoint = true;
     cc->debug_excp_handler = arm_debug_excp_handler;
     cc->debug_check_watchpoint = arm_debug_check_watchpoint;
+#if !defined(CONFIG_USER_ONLY)
+    cc->adjust_watchpoint_address = arm_adjust_watchpoint_address;
+#endif
 
     cc->disas_set_info = arm_disas_set_info;
 }
diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index ba796d8..fb366fd 100644
--- a/target/arm/op_helper.c
+++ b/target/arm/op_helper.c
@@ -1225,6 +1225,28 @@  bool arm_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp)
     return check_watchpoints(cpu);
 }
 
+vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+
+    /* In BE32 system mode, target memory is stored byteswapped (on a
+     * little-endian host system), and by the time we reach here (via an
+     * opcode helper) the addresses of subword accesses have been adjusted
+     * to account for that, which means that watchpoints will not match.
+     * Undo the adjustment here.
+     */
+    if (arm_sctlr_b(env)) {
+        if (len == 1) {
+            addr ^= 3;
+        } else if (len == 2) {
+            addr ^= 2;
+        }
+    }
+
+    return addr;
+}
+
 void arm_debug_excp_handler(CPUState *cs)
 {
     /* Called by core code when a watchpoint or breakpoint fires;