6656109 pstack should print proper python stack traces

6933514 mdb module load assumes shared libraries have single version number
6933515 mdb should learn to print python stacks

1 files changed, 461 insertions, 0 deletions

diff --git a/usr/src/cmd/mdb/common/modules/libpython2.6/libpython26.c b/usr/src/cmd/mdb/common/modules/libpython2.6/libpython26.c
new file mode 100644
index 0000000000..9d4635326d
--- /dev/null
+++ b/usr/src/cmd/mdb/common/modules/libpython2.6/libpython26.c
@@ -0,0 +1,461 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <mdb/mdb_modapi.h>
+
+#include <pthread.h>
+#include <stddef.h>
+#include <dlfcn.h>
+#include <link.h>
+#include <libproc.h>
+
+#include <python2.6/Python.h>
+#include <python2.6/frameobject.h>
+
+/*
+ * Decoding Python Stack Frames
+ * ============================
+ *
+ * Python2.6 uses a variety of objects to construct its call chain.  An address
+ * space may have one or more PyInterpreterState objects, which are the base
+ * object in the interpreter's state.  These objects are kept in a linked list
+ * with a head pointer named interp_head.  This makes it possible for the
+ * debugger to get a toehold on data structures necessary to understand the
+ * interpreter.  Since most of these structures are linked out of the
+ * InterpreterState, traversals generally start here.
+ *
+ * In order to decode a frame, the debugger needs to walk from
+ * PyInterpreterState down to a PyCodeObject.  The diagram below shows the
+ * the objects that must be examined in order to reach a leaf PyCodeObject.
+ *
+ *                +--------------------+ next   +--------------------+ next
+ * interp_head -> | PyInterpreterState | ---->  | PyInterpreterState | ---> ...
+ *                +--------------------+        +--------------------+
+ *                  |                            | tstate_head
+ *                  | tstate_head                V
+ *                  |                 +---------------+  frame
+ *                  V                 | PyThreadState | -----> ...
+ *  +---------------+  frame          +---------------+
+ *  | PyThreadState |  ---> ...
+ *  +---------------+
+ *          | next
+ *          V
+ *  +---------------+  frame    +---------------+ f_back +---------------+
+ *  | PyThreadState |  ------>  | PyFrameObject | -----> | PyFrameObject |
+ *  +---------------+           +---------------+        +---------------+
+ *                                      |                       |
+ *                                      | f_code                | f_code
+ *                                      V                       V
+ *                              +--------------+               ...
+ *                              | PyCodeObject |
+ *                              +--------------+
+ *                 co_filename   |      |     | co_lnotab
+ *                 +-------------+      |     +-------------+
+ *                 |           co_name  |                   |
+ *                 V                    V                   V
+ * +----------------+          +----------------+         +----------------+
+ * | PyStringObject |          | PyStringObject |         | PyStringObject |
+ * +----------------+          +----------------+         +----------------+
+ *
+ * The interp_head pointer is a list of one or more PyInterpreterState
+ * objects.  Each of these objects can contain one or more PyThreadState
+ * objects.  The PyInterpreterState object keeps a pointer to the head of the
+ * list of PyThreadState objects as tstate_head.
+ *
+ * Each thread keeps ahold of its stack frames.  The PyThreadState object
+ * has a pointer to the topmost PyFrameObject, kept in frame.  The
+ * successive frames on the stack are kept linked in the PyFrameObject's
+ * f_back pointer, with each frame pointing to its caller.
+ *
+ * In order to decode each call frame, our code needs to look at the
+ * PyCodeObject for each frame.  Essentially, this is the code that is
+ * being executed in the frame.  The PyFrameObject keeps a pointer to this
+ * code object in f_code.  In order to print meaningful debug information,
+ * it's necessary to extract the Python filename (co_filename), the
+ * function name (co_name), and the line number within the file
+ * (co_lnotab).  The filename and function are stored as strings, but the
+ * line number is a mapping of bytecode offsets to line numbers.  The
+ * description of the lnotab algorithm lives here:
+ *
+ * http://svn.python.org/projects/python/trunk/Objects/lnotab_notes.txt
+ *
+ * In order to decode the frame, the debugger needs to walk each
+ * InterpreterState object.  For each InterpreterState, every PyThreadState
+ * must be traversed.  The PyThreadState objects point to the
+ * PyFrameObjects.  For every thread, we must walk the frames backwards and
+ * decode the strings that are in the PyCodeObjects.
+ */
+
+/*
+ * The Python-dependent debugging functionality lives in its own helper
+ * library.  The helper agent is provided by libpython2.6_db.so, which is also
+ * used by pstack(1) for debugging Python processes.
+ *
+ * Define needed prototypes here.
+ */
+
+#define	PYDB_VERSION	1
+typedef struct pydb_agent pydb_agent_t;
+typedef struct pydb_iter pydb_iter_t;
+
+typedef pydb_agent_t *(*pydb_agent_create_f)(struct ps_prochandle *P, int vers);
+typedef void (*pydb_agent_destroy_f)(pydb_agent_t *py);
+typedef int (*pydb_get_frameinfo_f)(pydb_agent_t *py, uintptr_t frame_addr,
+    char *fbuf, size_t bufsz, int verbose);
+typedef pydb_iter_t *(*pydb_iter_init_f)(pydb_agent_t *py, uintptr_t addr);
+typedef uintptr_t (*pydb_iter_next_f)(pydb_iter_t *iter);
+typedef void (*pydb_iter_fini_f)(pydb_iter_t *iter);
+
+static pydb_agent_create_f pydb_agent_create;
+static pydb_agent_destroy_f pydb_agent_destroy;
+static pydb_get_frameinfo_f pydb_get_frameinfo;
+static pydb_iter_init_f pydb_frame_iter_init;
+static pydb_iter_init_f pydb_interp_iter_init;
+static pydb_iter_init_f pydb_thread_iter_init;
+static pydb_iter_next_f pydb_iter_next;
+static pydb_iter_fini_f pydb_iter_fini;
+
+static pydb_agent_t *pydb_hdl = NULL;
+static void *pydb_dlhdl = NULL;
+
+/*ARGSUSED*/
+static int
+py_frame(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	char buf[1024];
+	int verbose = FALSE;
+
+	if (mdb_getopts(argc, argv,
+	    'v', MDB_OPT_SETBITS, TRUE, &verbose,
+	    NULL) != argc) {
+		return (DCMD_USAGE);
+	}
+
+	if (flags & DCMD_PIPE_OUT) {
+		mdb_warn("py_stack cannot output into a pipe\n");
+		return (DCMD_ERR);
+	}
+
+	if (!(flags & DCMD_ADDRSPEC)) {
+		mdb_warn("no address");
+		return (DCMD_USAGE);
+	}
+
+	if (pydb_get_frameinfo(pydb_hdl, addr, buf, sizeof (buf),
+	    verbose) < 0) {
+		mdb_warn("Unable to find frame at address %p\n", addr);
+		return (DCMD_ERR);
+	}
+
+	mdb_printf("%s", buf);
+
+	return (DCMD_OK);
+}
+
+int
+py_interp_walk_init(mdb_walk_state_t *wsp)
+{
+	pydb_iter_t *pdi;
+
+	pdi = pydb_interp_iter_init(pydb_hdl, wsp->walk_addr);
+
+	if (pdi == NULL) {
+		mdb_warn("unable to create interpreter iterator\n");
+		return (DCMD_ERR);
+	}
+
+	wsp->walk_data = pdi;
+
+	return (WALK_NEXT);
+}
+
+int
+py_walk_step(mdb_walk_state_t *wsp)
+{
+	pydb_iter_t *pdi = wsp->walk_data;
+	uintptr_t addr;
+	int status;
+
+	addr = pydb_iter_next(pdi);
+
+	if (addr == NULL) {
+		return (WALK_DONE);
+	}
+
+	status = wsp->walk_callback(addr, 0, wsp->walk_cbdata);
+
+	return (status);
+}
+
+void
+py_walk_fini(mdb_walk_state_t *wsp)
+{
+	pydb_iter_t *pdi = wsp->walk_data;
+	pydb_iter_fini(pdi);
+}
+
+int
+py_thread_walk_init(mdb_walk_state_t *wsp)
+{
+	pydb_iter_t *pdi;
+
+	pdi = pydb_thread_iter_init(pydb_hdl, wsp->walk_addr);
+	if (pdi == NULL) {
+		mdb_warn("unable to create thread iterator\n");
+		return (DCMD_ERR);
+	}
+
+	wsp->walk_data = pdi;
+
+	return (WALK_NEXT);
+}
+
+int
+py_frame_walk_init(mdb_walk_state_t *wsp)
+{
+	pydb_iter_t *pdi;
+
+	pdi = pydb_frame_iter_init(pydb_hdl, wsp->walk_addr);
+	if (pdi == NULL) {
+		mdb_warn("unable to create frame iterator\n");
+		return (DCMD_ERR);
+	}
+
+	wsp->walk_data = pdi;
+
+	return (WALK_NEXT);
+}
+
+/*ARGSUSED*/
+static int
+python_stack(uintptr_t addr, const PyThreadState *ts, uint_t *verbose)
+{
+	mdb_arg_t nargv;
+	uint_t nargc = (verbose != NULL && *verbose) ? 1 : 0;
+	/*
+	 * Pass the ThreadState to the frame walker. Have frame walker
+	 * call frame dcmd.
+	 */
+	mdb_printf("PyThreadState: %0?p\n", addr);
+
+	nargv.a_type = MDB_TYPE_STRING;
+	nargv.a_un.a_str = "-v";
+
+	if (mdb_pwalk_dcmd("pyframe", "pyframe", nargc, &nargv, addr) == -1) {
+		mdb_warn("can't walk 'pyframe'");
+		return (WALK_ERR);
+	}
+
+	return (WALK_NEXT);
+}
+
+/*ARGSUSED*/
+static int
+python_thread(uintptr_t addr, const PyInterpreterState *is, uint_t *verbose)
+{
+	/*
+	 * Pass the InterpreterState to the threadstate walker.
+	 */
+	if (mdb_pwalk("pythread", (mdb_walk_cb_t)python_stack, verbose,
+	    addr) == -1) {
+		mdb_warn("can't walk 'pythread'");
+		return (WALK_ERR);
+	}
+
+	return (WALK_NEXT);
+}
+
+/*ARGSUSED*/
+static int
+py_stack(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	uint_t verbose = FALSE;
+
+	if (mdb_getopts(argc, argv,
+	    'v', MDB_OPT_SETBITS, TRUE, &verbose,
+	    NULL) != argc)
+		return (DCMD_USAGE);
+
+	if (flags & DCMD_PIPE_OUT) {
+		mdb_warn("py_stack cannot output into a pipe\n");
+		return (DCMD_ERR);
+	}
+
+	if (flags & DCMD_ADDRSPEC) {
+		mdb_arg_t nargv;
+		uint_t nargc = verbose ? 1 : 0;
+
+		nargv.a_type = MDB_TYPE_STRING;
+		nargv.a_un.a_str = "-v";
+
+		if (mdb_pwalk_dcmd("pyframe", "pyframe", nargc, &nargv, addr)
+		    == -1) {
+			mdb_warn("can't walk 'pyframe'");
+			return (DCMD_ERR);
+		}
+		return (DCMD_OK);
+	}
+
+	if (mdb_walk("pyinterp", (mdb_walk_cb_t)python_thread,
+	    &verbose) == -1) {
+		mdb_warn("can't walk 'pyinterp'");
+		return (DCMD_ERR);
+	}
+
+	return (DCMD_OK);
+}
+
+static const mdb_dcmd_t dcmds[] = {
+	{ "pystack", "[-v]", "print python stacks", py_stack },
+	{ "pyframe", "[-v]", "print python frames", py_frame },
+	{ NULL }
+};
+
+static const mdb_walker_t walkers[] = {
+	{ "pyinterp", "walk python interpreter structures",
+		py_interp_walk_init, py_walk_step, py_walk_fini },
+	{ "pythread", "given an interpreter, walk the list of python threads",
+		py_thread_walk_init, py_walk_step, py_walk_fini },
+	{ "pyframe", "given a thread state, walk the list of frame objects",
+		py_frame_walk_init, py_walk_step, py_walk_fini },
+	{ NULL }
+};
+
+static const mdb_modinfo_t modinfo = {
+	MDB_API_VERSION, dcmds, walkers
+};
+
+/*ARGSUSED*/
+static int
+python_object_iter(void *cd, const prmap_t *pmp, const char *obj)
+{
+	char path[PATH_MAX];
+	char *name;
+	char *s1, *s2;
+	struct ps_prochandle *Pr = cd;
+
+	name = strstr(obj, "/libpython");
+
+	if (name) {
+		(void) strcpy(path, obj);
+		if (Pstatus(Pr)->pr_dmodel != PR_MODEL_NATIVE) {
+			s1 = name;
+			s2 = path + (s1 - obj);
+			(void) strcpy(s2, "/64");
+			s2 += 3;
+			(void) strcpy(s2, s1);
+		}
+
+		s1 = strstr(obj, ".so");
+		s2 = strstr(path, ".so");
+		(void) strcpy(s2, "_db");
+		s2 += 3;
+		(void) strcpy(s2, s1);
+
+		if ((pydb_dlhdl = dlopen(path, RTLD_LAZY|RTLD_GLOBAL)) != NULL)
+			return (1);
+	}
+
+	return (0);
+}
+
+static int
+python_db_init(void)
+{
+	struct ps_prochandle *Ph;
+
+	if (mdb_get_xdata("pshandle", &Ph, sizeof (Ph)) == -1) {
+		mdb_warn("couldn't read pshandle xdata\n");
+		dlclose(pydb_dlhdl);
+		pydb_dlhdl = NULL;
+		return (-1);
+	}
+
+	(void) Pobject_iter(Ph, python_object_iter, Ph);
+
+	pydb_agent_create = (pydb_agent_create_f)
+	    dlsym(pydb_dlhdl, "pydb_agent_create");
+	pydb_agent_destroy = (pydb_agent_destroy_f)
+	    dlsym(pydb_dlhdl, "pydb_agent_destroy");
+	pydb_get_frameinfo = (pydb_get_frameinfo_f)
+	    dlsym(pydb_dlhdl, "pydb_get_frameinfo");
+
+	pydb_frame_iter_init = (pydb_iter_init_f)
+	    dlsym(pydb_dlhdl, "pydb_frame_iter_init");
+	pydb_interp_iter_init = (pydb_iter_init_f)
+	    dlsym(pydb_dlhdl, "pydb_interp_iter_init");
+	pydb_thread_iter_init = (pydb_iter_init_f)
+	    dlsym(pydb_dlhdl, "pydb_thread_iter_init");
+	pydb_iter_next = (pydb_iter_next_f)dlsym(pydb_dlhdl, "pydb_iter_next");
+	pydb_iter_fini = (pydb_iter_fini_f)dlsym(pydb_dlhdl, "pydb_iter_fini");
+
+
+	if (pydb_agent_create == NULL || pydb_agent_destroy == NULL ||
+	    pydb_get_frameinfo == NULL || pydb_frame_iter_init == NULL ||
+	    pydb_interp_iter_init == NULL || pydb_thread_iter_init == NULL ||
+	    pydb_iter_next == NULL || pydb_iter_fini == NULL) {
+		mdb_warn("couldn't load pydb functions");
+		dlclose(pydb_dlhdl);
+		pydb_dlhdl = NULL;
+		return (-1);
+	}
+
+	pydb_hdl = pydb_agent_create(Ph, PYDB_VERSION);
+	if (pydb_hdl == NULL) {
+		mdb_warn("unable to create pydb_agent");
+		dlclose(pydb_dlhdl);
+		pydb_dlhdl = NULL;
+		return (-1);
+	}
+
+	return (0);
+}
+
+static void
+python_db_fini(void)
+{
+	if (pydb_dlhdl) {
+		pydb_agent_destroy(pydb_hdl);
+		pydb_hdl = NULL;
+
+		dlclose(pydb_dlhdl);
+		pydb_dlhdl = NULL;
+	}
+}
+
+const mdb_modinfo_t *
+_mdb_init(void)
+{
+	if (python_db_init() != 0)
+		return (NULL);
+
+	return (&modinfo);
+}
+
+void
+_mdb_fini(void)
+{
+	python_db_fini();
+}