[09/10] btrace, python: Enable calling the ptwrite listener.
Commit Message
From: Felix Willgerodt <felix.willgerodt@intel.com>
Adding a new function to btinfo that allows to call the python ptwrite listener
from inside GDB.
2019-05-29 Felix Willgerodt <felix.willgerodt@intel.com>
gdb/ChangeLog:
* btrace.h (btrace_thread_info): New member ptw_callback_fun.
* python/py-record-btrace.c (recpy_call_listener): New function.
(recpy_initialize_listener): Save recpy_call_listener in btinfo.
---
gdb/btrace.h | 8 +++++
gdb/python/py-record-btrace.c | 63 +++++++++++++++++++++++++++++++++++
2 files changed, 71 insertions(+)
Comments
Hello Felix,
> diff --git a/gdb/btrace.h b/gdb/btrace.h
> index 7a80f5a44e1..7ad3cb65a28 100644
> --- a/gdb/btrace.h
> +++ b/gdb/btrace.h
> @@ -354,6 +354,14 @@ struct btrace_thread_info
> stepping through the execution history. */
> std::vector<std::string> aux_data;
>
> + /* Function pointer to the ptwrite callback. Returns the string returned
> + by the ptwrite listener function or nullptr if no string is supposed to
> + be printed. */
> + gdb::unique_xmalloc_ptr<char> (*ptw_callback_fun) (
> + const uint64_t *payload,
> + const uint64_t *ip,
> + const void *ptw_listener);
> +
> /* PyObject pointer to the ptwrite listener function. */
> void *ptw_listener = nullptr;
>
> diff --git a/gdb/python/py-record-btrace.c b/gdb/python/py-record-btrace.c
> index c7ad47d64a0..42a0c29a348 100644
> --- a/gdb/python/py-record-btrace.c
> +++ b/gdb/python/py-record-btrace.c
> @@ -772,6 +772,68 @@ recpy_bt_function_call_history (PyObject *self, void
> *closure)
> return btpy_list_new (tinfo, first, last, 1, &recpy_func_type);
> }
>
> +/* Calling the ptwrite listener. Returns a pointer to the string that will be
> + printed or nullptr if nothing should be printed. */
> +gdb::unique_xmalloc_ptr<char>
> +recpy_call_listener (const uint64_t *payload, const uint64_t *ip,
> + const void *ptw_listener)
> +{
> + if ((PyObject *) ptw_listener == Py_None)
> + return nullptr;
> + else if ((PyObject *) ptw_listener == nullptr)
> + error (_("No valid ptwrite listener."));
PTW_LISTENER is declared void * in struct btrace_info. Couldn't we treat nullptr
as not-present?
> +
> + /* As Python is started as a seperate thread, we need to
> + acquire the GIL to safely call the listener function. */
> + PyGILState_STATE gstate = PyGILState_Ensure ();
> +
> + PyObject *py_ip = Py_None;
> + PyObject *py_payload = PyLong_FromUnsignedLongLong (*payload);
> + Py_INCREF (Py_None);
Are we dropping that reference again in the case that PY_IP gets overwritten?
> +
> + if (ip != nullptr)
> + py_ip = PyLong_FromUnsignedLongLong (*ip);
It wouldn't hurt to document that IP can be NULL whereas PAYLOAD cannot
in the function's comment.
> +
> + PyObject *py_result = PyObject_CallFunctionObjArgs ((PyObject *)
> ptw_listener,
> + py_payload, py_ip, NULL);
> +
> + if (PyErr_Occurred ())
> + {
> + gdbpy_print_stack ();
> + gdb_Py_DECREF (py_ip);
> + gdb_Py_DECREF (py_payload);
> + gdb_Py_DECREF (py_result);
> + PyGILState_Release (gstate);
> + error (_("Error while executing Python code."));
> + }
> +
> + gdb_Py_DECREF (py_ip);
> + gdb_Py_DECREF (py_payload);
> +
> + if (py_result == Py_None)
> + {
> + gdb_Py_DECREF (py_result);
> + PyGILState_Release (gstate);
> + return nullptr;
> + }
> +
> + gdb::unique_xmalloc_ptr<char> resultstring = gdbpy_obj_to_string
> (py_result);
> +
> + if (PyErr_Occurred ())
> + {
> + gdbpy_print_stack ();
> + gdb_Py_DECREF (py_result);
> + PyGILState_Release (gstate);
> + error (_("Error while executing Python code."));
> + }
> +
> + if (py_result != nullptr)
> + gdb_Py_DECREF (py_result);
Shouldn't we check that before using PY_RESULT above?
> + PyGILState_Release (gstate);
> +
> + return resultstring;
> +}
> +
> /* Helper function returning the current ptwrite listener. Returns nullptr
> in case of errors. */
>
> @@ -807,6 +869,7 @@ recpy_initialize_listener (ptid_t inferior_ptid)
>
> gdb_assert (tinfo != nullptr);
>
> + tinfo->btrace.ptw_callback_fun = &recpy_call_listener;
> tinfo->btrace.ptw_listener = get_ptwrite_listener ();
>
> return (PyObject *) tinfo->btrace.ptw_listener;
> --
> 2.20.1
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@@ -354,6 +354,14 @@ struct btrace_thread_info
stepping through the execution history. */
std::vector<std::string> aux_data;
+ /* Function pointer to the ptwrite callback. Returns the string returned
+ by the ptwrite listener function or nullptr if no string is supposed to
+ be printed. */
+ gdb::unique_xmalloc_ptr<char> (*ptw_callback_fun) (
+ const uint64_t *payload,
+ const uint64_t *ip,
+ const void *ptw_listener);
+
/* PyObject pointer to the ptwrite listener function. */
void *ptw_listener = nullptr;
@@ -772,6 +772,68 @@ recpy_bt_function_call_history (PyObject *self, void *closure)
return btpy_list_new (tinfo, first, last, 1, &recpy_func_type);
}
+/* Calling the ptwrite listener. Returns a pointer to the string that will be
+ printed or nullptr if nothing should be printed. */
+gdb::unique_xmalloc_ptr<char>
+recpy_call_listener (const uint64_t *payload, const uint64_t *ip,
+ const void *ptw_listener)
+{
+ if ((PyObject *) ptw_listener == Py_None)
+ return nullptr;
+ else if ((PyObject *) ptw_listener == nullptr)
+ error (_("No valid ptwrite listener."));
+
+ /* As Python is started as a seperate thread, we need to
+ acquire the GIL to safely call the listener function. */
+ PyGILState_STATE gstate = PyGILState_Ensure ();
+
+ PyObject *py_ip = Py_None;
+ PyObject *py_payload = PyLong_FromUnsignedLongLong (*payload);
+ Py_INCREF (Py_None);
+
+ if (ip != nullptr)
+ py_ip = PyLong_FromUnsignedLongLong (*ip);
+
+ PyObject *py_result = PyObject_CallFunctionObjArgs ((PyObject *) ptw_listener,
+ py_payload, py_ip, NULL);
+
+ if (PyErr_Occurred ())
+ {
+ gdbpy_print_stack ();
+ gdb_Py_DECREF (py_ip);
+ gdb_Py_DECREF (py_payload);
+ gdb_Py_DECREF (py_result);
+ PyGILState_Release (gstate);
+ error (_("Error while executing Python code."));
+ }
+
+ gdb_Py_DECREF (py_ip);
+ gdb_Py_DECREF (py_payload);
+
+ if (py_result == Py_None)
+ {
+ gdb_Py_DECREF (py_result);
+ PyGILState_Release (gstate);
+ return nullptr;
+ }
+
+ gdb::unique_xmalloc_ptr<char> resultstring = gdbpy_obj_to_string (py_result);
+
+ if (PyErr_Occurred ())
+ {
+ gdbpy_print_stack ();
+ gdb_Py_DECREF (py_result);
+ PyGILState_Release (gstate);
+ error (_("Error while executing Python code."));
+ }
+
+ if (py_result != nullptr)
+ gdb_Py_DECREF (py_result);
+ PyGILState_Release (gstate);
+
+ return resultstring;
+}
+
/* Helper function returning the current ptwrite listener. Returns nullptr
in case of errors. */
@@ -807,6 +869,7 @@ recpy_initialize_listener (ptid_t inferior_ptid)
gdb_assert (tinfo != nullptr);
+ tinfo->btrace.ptw_callback_fun = &recpy_call_listener;
tinfo->btrace.ptw_listener = get_ptwrite_listener ();
return (PyObject *) tinfo->btrace.ptw_listener;