plugins: Copy memory in qemu_plugin_insn_data

Instead of returning a host pointer, copy the data into
storage provided by the caller.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

contrib/plugins/execlog.c

@@ -258,8 +258,9 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
                                                        NULL);
             }
         } else {
-            uint32_t insn_opcode;
-            insn_opcode = *((uint32_t *)qemu_plugin_insn_data(insn));
+            uint32_t insn_opcode = 0;
+            qemu_plugin_insn_data(insn, &insn_opcode, sizeof(insn_opcode));
+
             char *output = g_strdup_printf("0x%"PRIx64", 0x%"PRIx32", \"%s\"",
                                            insn_vaddr, insn_opcode, insn_disas);
 

contrib/plugins/howvec.c

@@ -252,7 +252,7 @@ static struct qemu_plugin_scoreboard *find_counter(
 {
     int i;
     uint64_t *cnt = NULL;
-    uint32_t opcode;
+    uint32_t opcode = 0;
     InsnClassExecCount *class = NULL;
 
     /*
@@ -261,7 +261,7 @@ static struct qemu_plugin_scoreboard *find_counter(
      * They would probably benefit from a more tailored plugin.
      * However we can fall back to individual instruction counting.
      */
-    opcode = *((uint32_t *)qemu_plugin_insn_data(insn));
+    qemu_plugin_insn_data(insn, &opcode, sizeof(opcode));
 
     for (i = 0; !cnt && i < class_table_sz; i++) {
         class = &class_table[i];

include/qemu/qemu-plugin.h

@@ -61,7 +61,7 @@ typedef uint64_t qemu_plugin_id_t;
 
 extern QEMU_PLUGIN_EXPORT int qemu_plugin_version;
 
-#define QEMU_PLUGIN_VERSION 2
+#define QEMU_PLUGIN_VERSION 3
 
 /**
  * struct qemu_info_t - system information for plugins
@@ -394,17 +394,16 @@ struct qemu_plugin_insn *
 qemu_plugin_tb_get_insn(const struct qemu_plugin_tb *tb, size_t idx);
 
 /**
- * qemu_plugin_insn_data() - return ptr to instruction data
+ * qemu_plugin_insn_data() - copy instruction data
  * @insn: opaque instruction handle from qemu_plugin_tb_get_insn()
+ * @dest: destination into which data is copied
+ * @len: length of dest
  *
- * Note: data is only valid for duration of callback. See
- * qemu_plugin_insn_size() to calculate size of stream.
- *
- * Returns: pointer to a stream of bytes containing the value of this
- * instructions opcode.
+ * Returns the number of bytes copied, minimum of @len and insn size.
  */
 QEMU_PLUGIN_API
-const void *qemu_plugin_insn_data(const struct qemu_plugin_insn *insn);
+size_t qemu_plugin_insn_data(const struct qemu_plugin_insn *insn,
+                             void *dest, size_t len);
 
 /**
  * qemu_plugin_insn_size() - return size of instruction

plugins/api.c

@@ -216,9 +216,12 @@ qemu_plugin_tb_get_insn(const struct qemu_plugin_tb *tb, size_t idx)
  * instruction being translated.
  */
 
-const void *qemu_plugin_insn_data(const struct qemu_plugin_insn *insn)
+size_t qemu_plugin_insn_data(const struct qemu_plugin_insn *insn,
+                             void *dest, size_t len)
 {
-    return insn->data->data;
+    len = MIN(len, insn->data->len);
+    memcpy(dest, insn->data->data, len);
+    return len;
 }
 
 size_t qemu_plugin_insn_size(const struct qemu_plugin_insn *insn)