Bring gdb's physical memory access handling up to speed with the CPU
memory access, by setting MemTxAttribute.debug=1, and by checking for
memory transaction errors.

GDB with PhyMemMode will now report failure for memory access outside
valid system memory addresses, and it is also able to write to ROMs as
it can with virtual memory access.

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 gdbstub/system.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/gdbstub/system.c b/gdbstub/system.c
index dd22ff0fb3a..6a550e229e2 100644
--- a/gdbstub/system.c
+++ b/gdbstub/system.c
@@ -17,6 +17,7 @@
 #include "exec/gdbstub.h"
 #include "gdbstub/syscalls.h"
 #include "gdbstub/commands.h"
+#include "exec/address-spaces.h"
 #include "exec/hwaddr.h"
 #include "exec/tb-flush.h"
 #include "system/accel-ops.h"
@@ -453,16 +454,30 @@ void gdb_qemu_exit(int code)
  */
 static int phy_memory_mode;
 
+/*
+ * Like cpu_memory_rw_debug but it operates on the system address space
+ * rather than the CPU's view of memory.
+ */
+static int phys_memory_rw_debug(hwaddr addr, void *buf,
+                                hwaddr len, bool is_write)
+{
+    MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
+    MemTxResult res;
+
+    attrs.debug = 1;
+    res = address_space_rw(&address_space_memory, addr, attrs,
+                           buf, len, is_write);
+    if (res != MEMTX_OK) {
+        return -1;
+    }
+    return 0;
+}
+
 int gdb_target_memory_rw_debug(CPUState *cpu, hwaddr addr,
                                uint8_t *buf, int len, bool is_write)
 {
     if (phy_memory_mode) {
-        if (is_write) {
-            cpu_physical_memory_write(addr, buf, len);
-        } else {
-            cpu_physical_memory_read(addr, buf, len);
-        }
-        return 0;
+        return phys_memory_rw_debug(addr, buf, len, is_write);
     }
 
     if (cpu->cc->memory_rw_debug) {
-- 
2.47.1