[PATCH-for-5.0] gdbstub: Do not use memset() on GByteArray

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Introduce gdb_get_zeroes() to fill a GByteArray with zeroes.

Fixes: a010bdbe719 ("extend GByteArray to read register helpers")
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/exec/gdbstub.h  | 9 +++++++++
 target/arm/gdbstub.c    | 3 +--
 target/xtensa/gdbstub.c | 6 ++----
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 30b909ebd2..b52d9933ee 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -125,6 +125,15 @@ static inline int gdb_get_reg128(GByteArray *buf, uint64_t val_hi,
     return 16;
 }
 
+static inline int gdb_get_zeroes(GByteArray *array, size_t len)
+{
+    for (size_t i = 0; i < len; i++) {
+        gdb_get_reg8(array, '\0');
+    }
+
+    return len;
+}
+
 /**
  * gdb_get_reg_ptr: get pointer to start of last element
  * @len: length of element
diff --git a/target/arm/gdbstub.c b/target/arm/gdbstub.c
index 8efc535f2a..063551df23 100644
--- a/target/arm/gdbstub.c
+++ b/target/arm/gdbstub.c
@@ -47,8 +47,7 @@ int arm_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
         if (gdb_has_xml) {
             return 0;
         }
-        memset(mem_buf, 0, 12);
-        return 12;
+        return gdb_get_zeroes(mem_buf, 12);
     }
     switch (n) {
     case 24:
diff --git a/target/xtensa/gdbstub.c b/target/xtensa/gdbstub.c
index 0ee3feabe5..4d43f1340a 100644
--- a/target/xtensa/gdbstub.c
+++ b/target/xtensa/gdbstub.c
@@ -105,8 +105,7 @@ int xtensa_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
         default:
             qemu_log_mask(LOG_UNIMP, "%s from reg %d of unsupported size %d\n",
                           __func__, n, reg->size);
-            memset(mem_buf, 0, reg->size);
-            return reg->size;
+            return gdb_get_zeroes(mem_buf, reg->size);
         }
 
     case xtRegisterTypeWindow: /*a*/
@@ -115,8 +114,7 @@ int xtensa_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
     default:
         qemu_log_mask(LOG_UNIMP, "%s from reg %d of unsupported type %d\n",
                       __func__, n, reg->type);
-        memset(mem_buf, 0, reg->size);
-        return reg->size;
+        return gdb_get_zeroes(mem_buf, reg->size);
     }
 }
 
-- 
2.21.1