plugin: add qemu_plugin_insn_disas helper

Give the plugins access to the QEMU dissasembler so they don't have to
re-invent the wheel. We generate a warning when there are spare bytes
in the decode buffer. This is usually due to the front end loading in
more bytes than decoded.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

include/disas/disas.h

@@ -14,6 +14,8 @@ void target_disas(FILE *out, CPUState *cpu, target_ulong code,
 void monitor_disas(Monitor *mon, CPUState *cpu,
                    target_ulong pc, int nb_insn, int is_physical);
 
+char *plugin_disas(CPUState *cpu, uint64_t addr, size_t size);
+
 /* Look up symbol for debugging purpose.  Returns "" if unknown. */
 const char *lookup_symbol(target_ulong orig_addr);
 #endif

include/qemu/qemu-plugin.h

@@ -351,6 +351,15 @@ qemu_plugin_register_vcpu_syscall_ret_cb(qemu_plugin_id_t id,
                                          qemu_plugin_vcpu_syscall_ret_cb_t cb);
 
 
+/**
+ * qemu_plugin_insn_disas() - return disassembly string for instruction
+ * @insn: instruction reference
+ *
+ * Returns an allocated string containing the disassembly
+ */
+
+char *qemu_plugin_insn_disas(const struct qemu_plugin_insn *insn);
+
 /**
  * qemu_plugin_vcpu_for_each() - iterate over the existing vCPU
  * @id: plugin ID