debug: Add CeaseStepiTest.

Test that we work correctly when the hart we're debugging ceases to
respond during stepi.

Add wait parameter to Gdb.stepi(), in case stepi isn't expected to complete.
Parse "could not read registers" error from gdb

2 files changed, 37 insertions, 3 deletions

diff --git a/debug/gdbserver.py b/debug/gdbserver.py
index 6d7c197..6f27871 100755
--- a/debug/gdbserver.py
+++ b/debug/gdbserver.py
@@ -18,6 +18,7 @@ from testlib import assertGreater, assertRegex, assertLess
 from testlib import GdbTest, GdbSingleHartTest, TestFailed
 from testlib import TestNotApplicable, CompileError
 from testlib import UnknownThread
+from testlib import CouldNotReadRegisters
 
 MSTATUS_UIE = 0x00000001
 MSTATUS_SIE = 0x00000002
@@ -1832,6 +1833,28 @@ class CeaseMultiTest(GdbTest):
         self.gdb.p("$pc=_start")
 
         self.exit()
+class CeaseStepiTest(ProgramTest):
+    """Test that we work correctly when the hart we're debugging ceases to
+    respond."""
+    def early_applicable(self):
+        return self.hart.support_cease
+
+    def test(self):
+        self.gdb.b("main")
+        output = self.gdb.c()
+        assertIn("Breakpoint", output)
+        assertIn("main", output)
+
+        self.gdb.p("$pc=cease")
+        self.gdb.stepi(wait=False)
+        self.gdb.expect(r"\S+ became unavailable.")
+        self.gdb.interrupt()
+        try:
+            self.gdb.p("$pc")
+            assert False, ("Registers shouldn't be accessible when the hart is "
+                           "unavailable.")
+        except CouldNotReadRegisters:
+            pass
 
 class FreeRtosTest(GdbTest):
     def early_applicable(self):
diff --git a/debug/testlib.py b/debug/testlib.py
index 5c78bd7..58bb23e 100644
--- a/debug/testlib.py
+++ b/debug/testlib.py
@@ -476,6 +476,11 @@ class CouldNotFetch(Exception):
         self.regname = regname
         self.explanation = explanation
 
+class CouldNotReadRegisters(Exception):
+    def __init__(self, explanation):
+        Exception.__init__(self)
+        self.explanation = explanation
+
 class NoSymbol(Exception):
     def __init__(self, symbol):
         Exception.__init__(self)
@@ -508,6 +513,8 @@ def tokenize(text):
                 (r"<repeats (\d+) times>", lambda m: Repeat(int(m.group(1)))),
                 (r"Could not fetch register \"(\w+)\"; (.*)$",
                     lambda m: CouldNotFetch(m.group(1), m.group(2))),
+                (r"Could not read registers; (.*)$",
+                    lambda m: CouldNotReadRegisters(m.group(1))),
                 (r"Cannot access memory at address (0x[0-9a-f]+)",
                     lambda m: CannotAccess(int(m.group(1), 0))),
                 (r"Cannot insert breakpoint (\d+).",
@@ -857,9 +864,13 @@ class Gdb:
                 result[name] = parse_rhs(parts[1])
         return result
 
-    def stepi(self):
-        output = self.command("stepi", ops=10)
-        return output
+    def stepi(self, wait=True):
+        if wait:
+            return self.command("stepi", ops=10)
+        else:
+            self.active_child.sendline("stepi")
+            self.active_child.expect("stepi", timeout=self.timeout)
+            return ""
 
     def expect(self, text, ops=1):
         return self.active_child.expect(text, timeout=ops * self.timeout)