Merge branch 'user_unwind'

17 files changed, 311 insertions, 63 deletions

diff --git a/runtime/stack-arm.c b/runtime/stack-arm.c
index 9b0b772d..fcff0a3b 100644
--- a/runtime/stack-arm.c
+++ b/runtime/stack-arm.c
@@ -31,7 +31,8 @@ static int __init find_str_pc_offset(void)
 }
 
 
-static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
+static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels,
+                               struct task_struct *tsk)
 {
 #ifdef STP_USE_FRAME_POINTER
 	int		pc_offset = find_str_pc_offset();
diff --git a/runtime/stack-i386.c b/runtime/stack-i386.c
index 5a18c9d8..69623765 100644
--- a/runtime/stack-i386.c
+++ b/runtime/stack-i386.c
@@ -23,14 +23,15 @@ static void _stp_stack_print_fallback(unsigned long stack, int verbose, int leve
 			/* cannot access stack.  give up. */
 			return;
 		}
-		if (_stp_func_print(addr, verbose, 0))
+		if (_stp_func_print(addr, verbose, 0, NULL))
 			levels--;
 		stack++;
 	}
 }
 #endif
 
-static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
+static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels,
+                               struct task_struct *tsk)
 {
 	unsigned long context = (unsigned long)&REG_SP(regs) & ~(THREAD_SIZE - 1);
 
@@ -43,7 +44,7 @@ static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
 			/* cannot access stack.  give up. */
 			return;
 		}
-		_stp_func_print(addr, verbose, 1);
+		_stp_func_print(addr, verbose, 1, NULL);
 		if (unlikely(_stp_read_address(next_fp, (unsigned long *)fp, KERNEL_DS))) {
 			/* cannot access stack.  give up. */
 			return;
@@ -60,19 +61,23 @@ static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
 	struct unwind_frame_info info;
 	arch_unw_init_frame_info(&info, regs);
 
-	while (levels && !arch_unw_user_mode(&info)) {
-		int ret = unwind(&info);
+	while (levels && (tsk || !arch_unw_user_mode(&info))) {
+		int ret = unwind(&info, tsk);
 		dbug_unwind(1, "ret=%d PC=%lx SP=%lx\n", ret, UNW_PC(&info), UNW_SP(&info));
 		if (ret == 0) {
-			_stp_func_print(UNW_PC(&info), verbose, 1);
+			_stp_func_print(UNW_PC(&info), verbose, 1, tsk);
 			levels--;
 			continue;
 		}
-		/* If an error happened or we hit a kretprobe trampoline, use fallback backtrace */
-		/* FIXME: is there a way to unwind across kretprobe trampolines? */
-		if (ret < 0 || (ret > 0 && UNW_PC(&info) == _stp_kretprobe_trampoline))
+		/* If an error happened or we hit a kretprobe trampoline,
+		 * use fallback backtrace, unless user task backtrace.
+		 * FIXME: is there a way to unwind across kretprobe
+		 * trampolines? */
+		if ((ret < 0
+		     || (ret > 0 && UNW_PC(&info) == _stp_kretprobe_trampoline))
+		    && ! (tsk || arch_unw_user_mode(&info)))
 			_stp_stack_print_fallback(UNW_SP(&info), verbose, levels);
-		break;
+		return;
 	}
 #else /* ! STP_USE_DWARF_UNWINDER */
 	_stp_stack_print_fallback((unsigned long)&REG_SP(regs), verbose, levels);
diff --git a/runtime/stack-ia64.c b/runtime/stack-ia64.c
index ca9d25a6..a04355fa 100644
--- a/runtime/stack-ia64.c
+++ b/runtime/stack-ia64.c
@@ -48,7 +48,8 @@ static void __stp_show_stack_addr(struct unw_frame_info *info, void *arg)
 	} while (unw_unwind(info) >= 0);
 }
 
-static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
+static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels,
+                               struct task_struct *tsk)
 {
 	unsigned long *stack = (unsigned long *)&REG_SP(regs);
 	struct dump_para para;
diff --git a/runtime/stack-ppc64.c b/runtime/stack-ppc64.c
index 3dc38526..3267194e 100644
--- a/runtime/stack-ppc64.c
+++ b/runtime/stack-ppc64.c
@@ -7,7 +7,8 @@
  * later version.
  */
 
-static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
+static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels,
+                               struct task_struct *tsk)
 {
 	unsigned long ip, newsp, lr = 0;
 	int count = 0;
diff --git a/runtime/stack-s390.c b/runtime/stack-s390.c
index c9654102..14e9b7d8 100644
--- a/runtime/stack-s390.c
+++ b/runtime/stack-s390.c
@@ -66,7 +66,8 @@ __stp_show_stack (unsigned long sp, unsigned long low,
 }
  
 static void __stp_stack_print (struct pt_regs *regs,
-			       int verbose, int levels)
+			       int verbose, int levels,
+	                       struct task_struct *tsk)
 {
 		unsigned long *_sp = (unsigned long *)&REG_SP(regs);
 		unsigned long sp = (unsigned long)_sp;
diff --git a/runtime/stack-x86_64.c b/runtime/stack-x86_64.c
index 03d88ef0..9afdf38a 100644
--- a/runtime/stack-x86_64.c
+++ b/runtime/stack-x86_64.c
@@ -19,7 +19,7 @@ static void _stp_stack_print_fallback(unsigned long stack, int verbose, int leve
 			/* cannot access stack.  give up. */
 			return;
 		}
-		if (_stp_func_print(addr, verbose, 0))
+		if (_stp_func_print(addr, verbose, 0, NULL))
 			levels--;
 		stack++;
 	}
@@ -27,26 +27,31 @@ static void _stp_stack_print_fallback(unsigned long stack, int verbose, int leve
 #endif
 
 
-static void __stp_stack_print(struct pt_regs *regs, int verbose, int levels)
+static void __stp_stack_print(struct pt_regs *regs, int verbose, int levels,
+                              struct task_struct *tsk)
 {
 #ifdef STP_USE_DWARF_UNWINDER
 	// FIXME: large stack allocation
 	struct unwind_frame_info info;
 	arch_unw_init_frame_info(&info, regs);
 
-	while (levels && !arch_unw_user_mode(&info)) {
-		int ret = unwind(&info);
+	while (levels && (tsk || !arch_unw_user_mode(&info))) {
+		int ret = unwind(&info, tsk);
 		dbug_unwind(1, "ret=%d PC=%lx SP=%lx\n", ret, UNW_PC(&info), UNW_SP(&info));
 		if (ret == 0) {
-			_stp_func_print(UNW_PC(&info), verbose, 1);
+			_stp_func_print(UNW_PC(&info), verbose, 1, tsk);
 			levels--;
 			continue;
 		}
-		/* If an error happened or we hit a kretprobe trampoline, use fallback backtrace */
-		/* FIXME: is there a way to unwind across kretprobe trampolines? */
-		if (ret < 0 || (ret > 0 && UNW_PC(&info) == _stp_kretprobe_trampoline))
+		/* If an error happened or we hit a kretprobe trampoline,
+		 * use fallback backtrace, unless user task backtrace.
+		 * FIXME: is there a way to unwind across kretprobe
+		 * trampolines? */
+		if ((ret < 0
+		     || (ret > 0 && UNW_PC(&info) == _stp_kretprobe_trampoline))
+		    && ! (tsk || arch_unw_user_mode(&info)))
 			_stp_stack_print_fallback(UNW_SP(&info), verbose, levels);
-		break;
+		return;
 	}
 #else /* ! STP_USE_DWARF_UNWINDER */
 	_stp_stack_print_fallback(REG_SP(regs), verbose, levels);
diff --git a/runtime/stack.c b/runtime/stack.c
index 68fb9b1f..042f44c7 100644
--- a/runtime/stack.c
+++ b/runtime/stack.c
@@ -1,6 +1,6 @@
 /*  -*- linux-c -*-
  * Stack tracing functions
- * Copyright (C) 2005-2008 Red Hat Inc.
+ * Copyright (C) 2005-2009 Red Hat Inc.
  * Copyright (C) 2005 Intel Corporation.
  *
  * This file is part of systemtap, and is free software.  You can
@@ -77,7 +77,7 @@ static void print_stack_address(void *data, unsigned long addr, int reliable)
 {
 	struct print_stack_data *sdata = data;
         if (sdata->level++ < sdata->max_level)
-                _stp_func_print(addr,sdata->verbose, 0);
+                _stp_func_print(addr, sdata->verbose, 0, NULL);
 }
 
 static const struct stacktrace_ops print_stack_ops = {
@@ -107,7 +107,7 @@ static void _stp_stack_print_fallback(unsigned long stack, int verbose, int leve
  * @param regs A pointer to the struct pt_regs.
  */
 
-static void _stp_stack_print(struct pt_regs *regs, int verbose, struct kretprobe_instance *pi, int levels)
+static void _stp_stack_print(struct pt_regs *regs, int verbose, struct kretprobe_instance *pi, int levels, struct task_struct *tsk)
 {
 	if (verbose) {
 		/* print the current address */
@@ -118,7 +118,10 @@ static void _stp_stack_print(struct pt_regs *regs, int verbose, struct kretprobe
 			_stp_symbol_print((unsigned long)_stp_ret_addr_r(pi));
 		} else {
 			_stp_print_char(' ');
-			_stp_symbol_print(REG_IP(regs));
+			if (tsk)
+			  _stp_usymbol_print(REG_IP(regs), tsk);
+			else
+			  _stp_symbol_print(REG_IP(regs));
 		}
 		_stp_print_char('\n');
 	} else if (pi)
@@ -126,7 +129,7 @@ static void _stp_stack_print(struct pt_regs *regs, int verbose, struct kretprobe
 	else 
 		_stp_printf("%p ", (int64_t) REG_IP(regs));
 
-	__stp_stack_print(regs, verbose, levels);
+	__stp_stack_print(regs, verbose, levels, tsk);
 }
 
 /** Writes stack backtrace to a string
@@ -135,37 +138,20 @@ static void _stp_stack_print(struct pt_regs *regs, int verbose, struct kretprobe
  * @param regs A pointer to the struct pt_regs.
  * @returns void
  */
-static void _stp_stack_snprint(char *str, int size, struct pt_regs *regs, int verbose, struct kretprobe_instance *pi, int levels)
+static void _stp_stack_snprint(char *str, int size, struct pt_regs *regs, int verbose, struct kretprobe_instance *pi, int levels, struct task_struct *tsk)
 {
 	/* To get a string, we use a simple trick. First flush the print buffer, */
 	/* then call _stp_stack_print, then copy the result into the output string  */
 	/* and clear the print buffer. */
 	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
 	_stp_print_flush();
-	_stp_stack_print(regs, verbose, pi, levels);
+	_stp_stack_print(regs, verbose, pi, levels, tsk);
 	strlcpy(str, pb->buf, size < (int)pb->len ? size : (int)pb->len);
 	pb->len = 0;
 }
 
 #endif /* CONFIG_KPROBES */
 
-/** Prints the user stack backtrace
- * @param str string
- * @returns Same string as was input with trace info appended,
- * @note Currently limited to a depth of two. Works from jprobes and kprobes.
- */
-#if 0
-static void _stp_ustack_print(char *str)
-{
-	struct pt_regs *nregs = ((struct pt_regs *)(THREAD_SIZE + (unsigned long)current->thread_info)) - 1;
-	_stp_printf("%p : [user]\n", (int64_t) REG_IP(nregs));
-	if (REG_SP(nregs))
-		_stp_printf("%p : [user]\n", (int64_t) (*(unsigned long *)REG_SP(nregs)));
-}
-#endif /* 0 */
-
-/** @} */
-
 void _stp_stack_print_tsk(struct task_struct *tsk, int verbose, int levels)
 {
 #if defined(STAPCONF_KERNEL_STACKTRACE)
diff --git a/runtime/sym.c b/runtime/sym.c
index f6f97ac2..013edd0c 100644
--- a/runtime/sym.c
+++ b/runtime/sym.c
@@ -329,8 +329,35 @@ static void _stp_symbol_print(unsigned long address)
 	}
 }
 
+/** Print an user space address from a specific task symbolically.
+ * @param address The address to lookup.
+ * @param task The address to lookup.
+ * @note Symbolic lookups should not normally be done within
+ * a probe because it is too time-consuming. Use at module exit time.
+ */
+
+static void _stp_usymbol_print(unsigned long address, struct task_struct *task)
+{
+	const char *modname;
+	const char *name;
+	unsigned long offset, size;
+
+	name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL,
+                                    task);
+
+	_stp_printf("%p", (int64_t) address);
+
+	if (name) {
+		if (modname && *modname)
+			_stp_printf(" : %s+%#lx/%#lx [%s]", name, offset, size, modname);
+		else
+			_stp_printf(" : %s+%#lx/%#lx", name, offset, size);
+	}
+}
+
 /* Like _stp_symbol_print, except only print if the address is a valid function address */
-static int _stp_func_print(unsigned long address, int verbose, int exact)
+static int _stp_func_print(unsigned long address, int verbose, int exact,
+                           struct task_struct *task)
 {
 	const char *modname;
 	const char *name;
@@ -342,7 +369,7 @@ static int _stp_func_print(unsigned long address, int verbose, int exact)
 	else
 		exstr = " (inexact)";
 
-	name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL, NULL);
+	name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL, task);
 
 	if (name) {
 		if (verbose) {
diff --git a/runtime/unwind.c b/runtime/unwind.c
index 41af72a7..aacd56f1 100644
--- a/runtime/unwind.c
+++ b/runtime/unwind.c
@@ -435,12 +435,18 @@ adjustStartLoc (unsigned long startLoc,
 		struct _stp_module *m,
 		struct _stp_section *s)
 {
-  if (startLoc && (strcmp (m->name, "kernel") != 0))
-    {
-      startLoc = _stp_module_relocate (m->name, s->name,
-				       startLoc);
-      startLoc -= m->dwarf_module_base;
-    }
+  /* XXX - some, or all, of this should really be done by
+     _stp_module_relocate. */
+  if (startLoc == 0
+      || strcmp (m->name, "kernel")  == 0
+      || strcmp (s->name, ".absolute") == 0)
+    return startLoc;
+
+  if (strcmp (s->name, ".dynamic") == 0)
+    return startLoc + s->addr;
+
+  startLoc = _stp_module_relocate (m->name, s->name, startLoc);
+  startLoc -= m->dwarf_module_base;
   return startLoc;
 }
 
@@ -562,7 +568,7 @@ static char *_stp_eh_enc_name(signed type)
 /* Unwind to previous to frame.  Returns 0 if successful, negative
  * number in case of an error.  A positive return means unwinding is finished; 
  * don't try to fallback to dumping addresses on the stack. */
-static int unwind(struct unwind_frame_info *frame)
+static int unwind(struct unwind_frame_info *frame, struct task_struct *tsk)
 {
 #define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs])
 	const u32 *fde, *cie = NULL;
@@ -581,7 +587,7 @@ static int unwind(struct unwind_frame_info *frame)
 	if (UNW_PC(frame) == 0)
 		return -EINVAL;
 
-	m = _stp_mod_sec_lookup (pc, current, &s);
+	m = _stp_mod_sec_lookup (pc, tsk, &s);
 	if (unlikely(m == NULL)) {
 		dbug_unwind(1, "No module found for pc=%lx", pc);
 		return -EINVAL;
diff --git a/tapset/context-symbols.stp b/tapset/context-symbols.stp
index 783f1b7b..e4406d9b 100644
--- a/tapset/context-symbols.stp
+++ b/tapset/context-symbols.stp
@@ -16,10 +16,10 @@
 #define STP_NEED_SYMBOL_DATA 1
 #endif
 %}
-// weirdness with print_stack, argument appears in build as undescribed
+
 /**
  * sfunction print_stack - Print out stack from string.
- * @stk: String with list of hexidecimal addresses. (FIXME)
+ * @stk: String with list of hexidecimal addresses.
  *
  *  Perform a symbolic lookup of the addresses in the given  string,
  *  which is assumed to be the result of a prior call to 
diff --git a/tapset/context-unwind.stp b/tapset/context-unwind.stp
index b3d19e29..f1e99dc8 100644
--- a/tapset/context-unwind.stp
+++ b/tapset/context-unwind.stp
@@ -28,7 +28,7 @@
  */
 function print_backtrace () %{
 	if (CONTEXT->regs) {
-		_stp_stack_print(CONTEXT->regs, 1, CONTEXT->pi, MAXTRACE);
+		_stp_stack_print(CONTEXT->regs, 1, CONTEXT->pi, MAXTRACE, NULL);
 	} else {
 		_stp_printf("Systemtap probe: %s\n", CONTEXT->probe_point);
 	}
@@ -42,7 +42,7 @@ function print_backtrace () %{
  */
 function backtrace:string () %{ /* pure */
 	if (CONTEXT->regs)
-		_stp_stack_snprint (THIS->__retvalue, MAXSTRINGLEN, CONTEXT->regs, 0, CONTEXT->pi, MAXTRACE);
+		_stp_stack_snprint (THIS->__retvalue, MAXSTRINGLEN, CONTEXT->regs, 0, CONTEXT->pi, MAXTRACE, NULL);
 	else 
 		strlcpy (THIS->__retvalue, "", MAXSTRINGLEN);
 %}
diff --git a/tapset/ucontext-symbols.stp b/tapset/ucontext-symbols.stp
index 3813a8bf..5502f5cd 100644
--- a/tapset/ucontext-symbols.stp
+++ b/tapset/ucontext-symbols.stp
@@ -23,7 +23,7 @@
 %}
 
 /**
- * sfunction usymname - Return the symbol of an address in the current task.
+ * sfunction usymname - Return the symbol of an address in the current task. EXPERIMENTAL!
  * @addr: The address to translate.
  *
  * Description: Returns the (function) symbol name associated with the
@@ -36,7 +36,7 @@ function usymname:string (addr: long) %{ /* pure */
 %}
 
 /**
- * sfunction usymdata - Return the symbol and module offset of an address.
+ * sfunction usymdata - Return the symbol and module offset of an address. EXPERIMENTAL!
  * @addr: The address to translate.
  *
  * Description: Returns the (function) symbol name associated with the
@@ -50,3 +50,26 @@ function usymdata:string (addr: long) %{ /* pure */
 	 _stp_symbol_snprint(THIS->__retvalue, MAXSTRINGLEN, THIS->addr,
 			     current, 1);
 %}
+
+/**
+ * sfunction print_ustack - Print out stack for the current task from string. EXPERIMENTAL!
+ * @stk: String with list of hexidecimal addresses for the current task.
+ *
+ *  Perform a symbolic lookup of the addresses in the given string,
+ *  which is assumed to be the result of a prior call to 
+ *  <command>ubacktrace()</command> for the current task.
+ * 
+ *  Print one line per address, including the address, the
+ *  name  of the function containing the address, and an estimate of
+ *  its position within that function.  Return nothing.
+ */
+function print_ustack(stk:string) %{
+        char *ptr = THIS->stk;
+        char *tok = strsep(&ptr, " ");
+        while (tok && *tok) {
+                _stp_print_char(' ');
+                _stp_usymbol_print (simple_strtol(tok, NULL, 16), current);
+                _stp_print_char('\n');
+                tok = strsep(&ptr, " ");
+        }
+%}
diff --git a/tapset/ucontext-unwind.stp b/tapset/ucontext-unwind.stp
new file mode 100644
index 00000000..0801f1c9
--- /dev/null
+++ b/tapset/ucontext-unwind.stp
@@ -0,0 +1,52 @@
+// User context unwind tapset
+// Copyright (C) 2009 Red Hat Inc.
+//
+// This file is part of systemtap, and is free software.  You can
+// redistribute it and/or modify it under the terms of the GNU General
+// Public License (GPL); either version 2, or (at your option) any
+// later version.
+
+%{
+#ifndef STP_NEED_UNWIND_DATA
+#define STP_NEED_UNWIND_DATA 1
+#endif
+#ifndef STP_NEED_SYMBOL_DATA
+#define STP_NEED_SYMBOL_DATA 1
+#endif
+#ifndef STP_NEED_VMA_TRACKER
+#define STP_NEED_VMA_TRACKER 1
+#endif
+%}
+
+/**
+ * sfunction print_ubacktrace - Print stack back trace for current task. EXPERIMENTAL!
+ *
+ *  Equivalent to <command>print_ustack(ubacktrace())</command>, 
+ *  except that deeper stack nesting may be supported.  Return nothing.
+ */
+function print_ubacktrace () %{
+	if (CONTEXT->regs) {
+		_stp_stack_print(CONTEXT->regs, 1, CONTEXT->pi, MAXTRACE,
+				 current);
+	} else {
+		_stp_printf("Systemtap probe: %s\n", CONTEXT->probe_point);
+	}
+%}
+
+/**
+ * sfunction ubacktrace - Hex backtrace of current task stack. EXPERIMENTAL!
+ *
+ *  Return a string of hex addresses that are a backtrace of the 
+ *  stack of the current task.  Output may be truncated as per maximum
+ *  string length. Returns empty string when current probe point cannot
+ *  determine user backtrace.
+ */
+
+function ubacktrace:string () %{ /* pure */
+	if (CONTEXT->regs)
+		_stp_stack_snprint (THIS->__retvalue, MAXSTRINGLEN,
+				    CONTEXT->regs, 0, CONTEXT->pi, MAXTRACE,
+				    current);
+	else 
+		strlcpy (THIS->__retvalue, "", MAXSTRINGLEN);
+%}
diff --git a/testsuite/buildok/ustack.stp b/testsuite/buildok/ustack.stp
new file mode 100755
index 00000000..23af0bff
--- /dev/null
+++ b/testsuite/buildok/ustack.stp
@@ -0,0 +1,10 @@
+#! stap -p4
+#
+# Test the translatability for ubacktrace(), print_ustack()
+# and print_ubacktrace()
+#
+probe begin
+{
+   print_ustack(ubacktrace());
+   print_ubacktrace();
+}
diff --git a/testsuite/systemtap.base/uprobes_ustack.exp b/testsuite/systemtap.base/uprobes_ustack.exp
new file mode 100644
index 00000000..f085fc16
--- /dev/null
+++ b/testsuite/systemtap.base/uprobes_ustack.exp
@@ -0,0 +1,94 @@
+set test "uprobes_ustack"
+set testpath "$srcdir/$subdir"
+set testsrc  "$testpath/uprobes_exe.c"
+set testsrclib  "$testpath/uprobes_lib.c"
+set testexe  "./uprobes_exe"
+set testlibname  "uprobes_lib"
+set testlibdir "."
+set testso  "$testlibdir/lib${testlibname}.so"
+set testflags "additional_flags=-g additional_flags=-O"
+set testlibflags "$testflags additional_flags=-fPIC additional_flags=-shared"
+set maintestflags "$testflags additional_flags=-L$testlibdir additional_flags=-l$testlibname additional_flags=-Wl,-rpath,$testlibdir"
+
+# Compile our test program and library.
+set res [target_compile $testsrclib $testso executable $testlibflags]
+if { $res != "" } {
+    verbose "target_compile for $testso failed: $res" 2
+    fail "$test compile $testsrclib"
+    return
+} else {
+    pass "$test compile $testsrclib"
+}
+
+set res [target_compile $testsrc $testexe executable $maintestflags]
+if { $res != "" } {
+    verbose "target_compile failed: $res" 2
+    fail "$test compile $testsrc"
+    return
+} else {
+    pass "$test compile $testsrc"
+}
+
+set ::result_string {exe: main=main
+exe: main_func=main_func
+exe: main_func=main_func
+exe: main_func=main_func
+lib: lib_main=lib_main
+lib: lib_func=lib_func
+lib: lib_func=lib_func
+lib: lib_func=lib_func}
+
+# Only run on make installcheck
+if {! [installtest_p]} { untested "$test"; return }
+if {! [utrace_p]} { untested $test; return }
+
+# Output is:
+#print_ubacktrace exe 0
+# 0x080484ba : main_func+0xa/0x29 [.../uprobes_exe]
+# 0x080484f6 : main+0x1d/0x37 [.../uprobes_exe]
+#print_ustack exe 1
+# 0x080484ba : main_func+0xa/0x29 [.../uprobes_exe]
+# 0x080484c9 : main_func+0x19/0x29 [.../uprobes_exe]
+# 0x080484f6 : main+0x1d/0x37 [.../uprobes_exe]
+#print_ubacktrace lib 2
+# 0x00db2422 : lib_func+0x16/0x2b [.../libuprobes_lib.so]
+# 0x00db2455 : lib_main+0x1e/0x29 [.../libuprobes_lib.so]
+# 0x080484d0 : main_func+0x20/0x29 [.../uprobes_exe]
+# 0x080484c9 : main_func+0x19/0x29 [.../uprobes_exe]
+# 0x080484c9 : main_func+0x19/0x29 [.../uprobes_exe]
+# 0x080484f6 : main+0x1d/0x37 [.../uprobes_exe]
+#print_ustack lib 3
+# 0x00db2422 : lib_func+0x16/0x2b [.../libuprobes_lib.so]
+# 0x00db2431 : lib_func+0x25/0x2b [.../libuprobes_lib.so]
+# 0x00db2455 : lib_main+0x1e/0x29 [.../libuprobes_lib.so]
+# 0x080484d0 : main_func+0x20/0x29 [.../uprobes_exe]
+# 0x080484c9 : main_func+0x19/0x29 [.../uprobes_exe]
+# 0x080484c9 : main_func+0x19/0x29 [.../uprobes_exe]
+# 0x080484f6 : main+0x1d/0x37 [.../uprobes_exe]
+
+set print 0
+set main 0
+set main_func 0
+set lib_main 0
+set lib_func 0
+spawn stap $srcdir/$subdir/$test.stp -c $testexe
+
+wait
+expect {
+  -timeout 60
+  -re {^print_[^\r\n]+\r\n} {incr print; exp_continue}
+  -re {^ 0x[a-f0-9]+ : main\+0x[^\r\n]+\r\n} {incr main; exp_continue}
+  -re {^ 0x[a-f0-9]+ : main_func\+0x[^\r\n]+\r\n} {incr main_func; exp_continue}
+  -re {^ 0x[a-f0-9]+ : lib_main\+0x[^\r\n]+\r\n} {incr lib_main; exp_continue}
+  -re {^ 0x[a-f0-9]+ : lib_func\+0x[^\r\n]+\r\n} {incr lib_func; exp_continue}
+  timeout { fail "$test (timeout)" }
+  eof { }
+}
+
+if {$print == 4} {pass "$test print"} {fail "$test print ($print)"}
+if {$main == 4} {pass "$test main"} {fail "$test main ($main)"}
+if {$main_func == 9} {pass "$test main_func"} {fail "$test main_func ($main_func)"}
+if {$lib_main == 2} {pass "$test lib_main"} {fail "$test lib_main ($lib_main)"}
+if {$lib_func == 3} {pass "$test lib_func"} {fail "$test lib_func ($lib_func)"}
+
+#exec rm -f $testexe $testso
diff --git a/testsuite/systemtap.base/uprobes_ustack.stp b/testsuite/systemtap.base/uprobes_ustack.stp
new file mode 100644
index 00000000..6de03b42
--- /dev/null
+++ b/testsuite/systemtap.base/uprobes_ustack.stp
@@ -0,0 +1,35 @@
+// Prints backtrace from lib through exe twice using diffent ustack functions.
+
+global hits = 0;
+
+probe process("uprobes_exe").function("main_func")
+{
+  if (hits == 0)
+    {
+      log("print_ubacktrace exe 0");
+      print_ubacktrace();
+      hits++;
+    }
+  else if (hits == 1)
+    {
+      log("print_ustack exe 1");
+      print_ustack(ubacktrace());
+      hits++;
+    }
+}
+
+probe process("libuprobes_lib.so").function("lib_func")
+{
+  if (hits == 2)
+    {
+      log("print_ubacktrace lib 2");
+      print_ubacktrace();
+      hits++;
+    }
+  else if (hits == 3)
+    {
+      log("print_ustack lib 3");
+      print_ustack(ubacktrace());
+      hits++;
+    }
+}
diff --git a/testsuite/systemtap.context/backtrace.tcl b/testsuite/systemtap.context/backtrace.tcl
index 6edda812..975e6c4d 100644
--- a/testsuite/systemtap.context/backtrace.tcl
+++ b/testsuite/systemtap.context/backtrace.tcl
@@ -5,6 +5,7 @@ set m4 0
 set m5 0
 set m6 0
 
+#spawn stap -d kernel -d systemtap_test_module1 -DMAXSTRINGLEN=256 $srcdir/$subdir/backtrace.stp
 spawn stap -DMAXSTRINGLEN=256 $srcdir/$subdir/backtrace.stp
 #exp_internal 1
 expect {