X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=debug%2Fgdbserver.py;h=17e1734010d13047c8215eba0a32b25643937b46;hb=HEAD;hp=21eea4ed521b2da90c18e301b06838784eb4c20d;hpb=a7238f6f683705a92a3216562d91cfc8979c75ed;p=riscv-tests.git

diff --git a/debug/gdbserver.py b/debug/gdbserver.py
index 21eea4e..17e1734 100755
--- a/debug/gdbserver.py
+++ b/debug/gdbserver.py
@@ -13,6 +13,7 @@ import testlib
 from testlib import assertEqual, assertNotEqual, assertIn, assertNotIn
 from testlib import assertGreater, assertRegexpMatches, assertLess
 from testlib import GdbTest, GdbSingleHartTest, TestFailed
+from testlib import assertTrue
 
 MSTATUS_UIE = 0x00000001
 MSTATUS_SIE = 0x00000002
@@ -65,15 +66,19 @@ def readable_binary_string(s):
     return "".join("%02x" % ord(c) for c in s)
 
 class SimpleRegisterTest(GdbTest):
-    def check_reg(self, name):
+    def check_reg(self, name, alias):
         a = random.randrange(1<<self.hart.xlen)
         b = random.randrange(1<<self.hart.xlen)
         self.gdb.p("$%s=0x%x" % (name, a))
+        assertEqual(self.gdb.p("$%s" % alias), a)
         self.gdb.stepi()
         assertEqual(self.gdb.p("$%s" % name), a)
-        self.gdb.p("$%s=0x%x" % (name, b))
+        assertEqual(self.gdb.p("$%s" % alias), a)
+        self.gdb.p("$%s=0x%x" % (alias, b))
+        assertEqual(self.gdb.p("$%s" % name), b)
         self.gdb.stepi()
         assertEqual(self.gdb.p("$%s" % name), b)
+        assertEqual(self.gdb.p("$%s" % alias), b)
 
     def setup(self):
         # 0x13 is nop
@@ -86,38 +91,95 @@ class SimpleRegisterTest(GdbTest):
 
 class SimpleS0Test(SimpleRegisterTest):
     def test(self):
-        self.check_reg("s0")
+        self.check_reg("s0", "x8")
 
 class SimpleS1Test(SimpleRegisterTest):
     def test(self):
-        self.check_reg("s1")
+        self.check_reg("s1", "x9")
 
 class SimpleT0Test(SimpleRegisterTest):
     def test(self):
-        self.check_reg("t0")
+        self.check_reg("t0", "x5")
 
 class SimpleT1Test(SimpleRegisterTest):
     def test(self):
-        self.check_reg("t1")
+        self.check_reg("t1", "x6")
 
 class SimpleF18Test(SimpleRegisterTest):
-    def check_reg(self, name):
-        self.gdb.p_raw("$mstatus=$mstatus | 0x00006000")
-        self.gdb.stepi()
-        a = random.random()
-        b = random.random()
-        self.gdb.p_raw("$%s=%f" % (name, a))
-        self.gdb.stepi()
-        assertLess(abs(float(self.gdb.p_raw("$%s" % name)) - a), .001)
-        self.gdb.p_raw("$%s=%f" % (name, b))
-        self.gdb.stepi()
-        assertLess(abs(float(self.gdb.p_raw("$%s" % name)) - b), .001)
+    def check_reg(self, name, alias):
+        if self.hart.extensionSupported('F'):
+            self.gdb.p_raw("$mstatus=$mstatus | 0x00006000")
+            self.gdb.stepi()
+            a = random.random()
+            b = random.random()
+            self.gdb.p_raw("$%s=%f" % (name, a))
+            assertLess(abs(float(self.gdb.p_raw("$%s" % alias)) - a), .001)
+            self.gdb.stepi()
+            assertLess(abs(float(self.gdb.p_raw("$%s" % name)) - a), .001)
+            assertLess(abs(float(self.gdb.p_raw("$%s" % alias)) - a), .001)
+            self.gdb.p_raw("$%s=%f" % (alias, b))
+            assertLess(abs(float(self.gdb.p_raw("$%s" % name)) - b), .001)
+            self.gdb.stepi()
+            assertLess(abs(float(self.gdb.p_raw("$%s" % name)) - b), .001)
+            assertLess(abs(float(self.gdb.p_raw("$%s" % alias)) - b), .001)
 
+            size = self.gdb.p("sizeof($%s)" % name)
+            if self.hart.extensionSupported('D'):
+                assertEqual(size, 8)
+            else:
+                assertEqual(size, 4)
+        else:
+            output = self.gdb.p_raw("$" + name)
+            assertEqual(output, "void")
+            output = self.gdb.p_raw("$" + alias)
+            assertEqual(output, "void")
+
+    def test(self):
+        self.check_reg("f18", "fs2")
+
+class CustomRegisterTest(SimpleRegisterTest):
     def early_applicable(self):
-        return self.hart.extensionSupported('F')
+        return self.target.implements_custom_test
+
+    def check_custom(self, magic):
+        regs = {k: v for k, v in self.gdb.info_registers("all").iteritems()
+                if k.startswith("custom")}
+        assertEqual(set(regs.keys()),
+                set(("custom1",
+                    "custom12345",
+                    "custom12346",
+                    "custom12347",
+                    "custom12348")))
+        for name, value in regs.iteritems():
+            number = int(name[6:])
+            if number % 2:
+                expect = number + magic
+                assertIn(value, (expect, expect + (1<<32)))
+            else:
+                assertIn("Could not fetch register", value)
 
     def test(self):
-        self.check_reg("f18")
+        self.check_custom(0)
+
+        # Now test writing
+        magic = 6667
+        self.gdb.p("$custom12345=%d" % (12345 + magic))
+        self.gdb.stepi()
+
+        self.check_custom(magic)
+
+class SimpleNoExistTest(GdbTest):
+    def test(self):
+        try:
+            self.gdb.p("$csr2288")
+            assert False, "Reading csr2288 should have failed"
+        except testlib.CouldNotFetch:
+            pass
+        try:
+            self.gdb.p("$csr2288=5")
+            assert False, "Writing csr2288 should have failed"
+        except testlib.CouldNotFetch:
+            pass
 
 class SimpleMemoryTest(GdbTest):
     def access_test(self, size, data_type):
@@ -184,8 +246,10 @@ class MemTestBlock(GdbTest):
             a.write(ihex_line(i * self.line_length, 0, line_data))
         a.flush()
 
+        self.gdb.command("shell cat %s" % a.name)
         self.gdb.command("restore %s 0x%x" % (a.name, self.hart.ram))
-        for offset in range(0, self.length, 19*4) + [self.length-4]:
+        increment = 19 * 4
+        for offset in range(0, self.length, increment) + [self.length-4]:
             value = self.gdb.p("*((int*)0x%x)" % (self.hart.ram + offset))
             written = ord(data[offset]) | \
                     (ord(data[offset+1]) << 8) | \
@@ -196,7 +260,8 @@ class MemTestBlock(GdbTest):
         b = tempfile.NamedTemporaryFile(suffix=".ihex")
         self.gdb.command("dump ihex memory %s 0x%x 0x%x" % (b.name,
             self.hart.ram, self.hart.ram + self.length))
-        for line in b:
+        self.gdb.command("shell cat %s" % b.name)
+        for line in b.xreadlines():
             record_type, address, line_data = ihex_parse(line)
             if record_type == 0:
                 written_data = data[address:address+len(line_data)]
@@ -217,7 +282,7 @@ class InstantHaltTest(GdbTest):
             self.gdb.thread(t)
             pcs.append(self.gdb.p("$pc"))
         for pc in pcs:
-            assertEqual(self.hart.reset_vector, pc)
+            assertIn(pc, self.hart.reset_vectors)
         # mcycle and minstret have no defined reset value.
         mstatus = self.gdb.p("$mstatus")
         assertEqual(mstatus & (MSTATUS_MIE | MSTATUS_MPRV |
@@ -363,7 +428,7 @@ class Hwbp2(DebugTest):
         self.exit()
 
 class TooManyHwbp(DebugTest):
-    def run(self):
+    def test(self):
         for i in range(30):
             self.gdb.hbreak("*rot13 + %d" % (i * 4))
 
@@ -385,6 +450,8 @@ class Registers(DebugTest):
             output = self.gdb.command(cmd)
             for reg in ('zero', 'ra', 'sp', 'gp', 'tp'):
                 assertIn(reg, output)
+            for line in output.splitlines():
+                assertRegexpMatches(line, r"^\S")
 
         #TODO
         # mcpuid is one of the few registers that should have the high bit set
@@ -419,6 +486,49 @@ class UserInterrupt(DebugTest):
         self.gdb.p("i=0")
         self.exit()
 
+class InterruptTest(GdbSingleHartTest):
+    compile_args = ("programs/interrupt.c",)
+
+    def early_applicable(self):
+        return self.target.supports_clint_mtime
+
+    def setup(self):
+        self.gdb.load()
+
+    def test(self):
+        self.gdb.b("main")
+        output = self.gdb.c()
+        assertIn(" main ", output)
+        self.gdb.b("trap_entry")
+        output = self.gdb.c()
+        assertIn(" trap_entry ", output)
+        assertEqual(self.gdb.p("$mip") & 0x80, 0x80)
+        assertEqual(self.gdb.p("interrupt_count"), 0)
+        # You'd expect local to still be 0, but it looks like spike doesn't
+        # jump to the interrupt handler immediately after the write to
+        # mtimecmp.
+        assertLess(self.gdb.p("local"), 1000)
+        self.gdb.command("delete breakpoints")
+        for _ in range(10):
+            self.gdb.c(wait=False)
+            time.sleep(2)
+            self.gdb.interrupt()
+            interrupt_count = self.gdb.p("interrupt_count")
+            local = self.gdb.p("local")
+            if interrupt_count > 1000 and \
+                    local > 1000:
+                return
+
+        assertGreater(interrupt_count, 1000)
+        assertGreater(local, 1000)
+
+    def postMortem(self):
+        GdbSingleHartTest.postMortem(self)
+        self.gdb.p("*((long long*) 0x200bff8)")
+        self.gdb.p("*((long long*) 0x2004000)")
+        self.gdb.p("interrupt_count")
+        self.gdb.p("local")
+
 class MulticoreRegTest(GdbTest):
     compile_args = ("programs/infinite_loop.S", "-DMULTICORE")
 
@@ -433,21 +543,24 @@ class MulticoreRegTest(GdbTest):
 
     def test(self):
         # Run to main
-        self.gdb.b("main")
-        self.gdb.c()
-        for t in self.gdb.threads():
-            assertIn("main", t.frame)
-        self.gdb.command("delete breakpoints")
+        for hart in self.target.harts:
+            self.gdb.select_hart(hart)
+            self.gdb.b("main")
+            self.gdb.c()
+            assertIn("main", self.gdb.where())
+            self.gdb.command("delete breakpoints")
 
         # Run through the entire loop.
-        self.gdb.b("main_end")
-        self.gdb.c()
+        for hart in self.target.harts:
+            self.gdb.select_hart(hart)
+            self.gdb.b("main_end")
+            self.gdb.c()
+            assertIn("main_end", self.gdb.where())
 
         hart_ids = []
-        for t in self.gdb.threads():
-            assertIn("main_end", t.frame)
+        for hart in self.target.harts:
+            self.gdb.select_hart(hart)
             # Check register values.
-            self.gdb.thread(t)
             hart_id = self.gdb.p("$x1")
             assertNotIn(hart_id, hart_ids)
             hart_ids.append(hart_id)
@@ -462,45 +575,126 @@ class MulticoreRegTest(GdbTest):
             self.gdb.select_hart(hart)
             self.gdb.p("$x1=0x%x" % (hart.index * 0x800))
             self.gdb.p("$pc=main_post_csrr")
-        self.gdb.c()
-        for t in self.gdb.threads():
-            assertIn("main_end", t.frame)
+            self.gdb.c()
         for hart in self.target.harts:
-            # Check register values.
             self.gdb.select_hart(hart)
+            assertIn("main", self.gdb.where())
+            # Check register values.
             for n in range(1, 32):
                 value = self.gdb.p("$x%d" % n)
                 assertEqual(value, hart.index * 0x800 + n - 1)
 
-class MulticoreRunHaltStepiTest(GdbTest):
+#class MulticoreRunHaltStepiTest(GdbTest):
+#    compile_args = ("programs/multicore.c", "-DMULTICORE")
+#
+#    def early_applicable(self):
+#        return len(self.target.harts) > 1
+#
+#    def setup(self):
+#        self.gdb.load()
+#        for hart in self.target.harts:
+#            self.gdb.select_hart(hart)
+#            self.gdb.p("$mhartid")
+#            self.gdb.p("$pc=_start")
+#
+#    def test(self):
+#        previous_hart_count = [0 for h in self.target.harts]
+#        previous_interrupt_count = [0 for h in self.target.harts]
+#        # Check 10 times
+#        for i in range(10):
+#            # 3 attempts for each time we want the check to pass
+#            for attempt in range(3):
+#                self.gdb.global_command("echo round %d attempt %d\\n" % (i,
+#                    attempt))
+#                self.gdb.c_all(wait=False)
+#                time.sleep(2)
+#                self.gdb.interrupt_all()
+#                hart_count = self.gdb.p("hart_count")
+#                interrupt_count = self.gdb.p("interrupt_count")
+#                ok = True
+#                for i, h in enumerate(self.target.harts):
+#                    if hart_count[i] <= previous_hart_count[i]:
+#                        ok = False
+#                        break
+#                    if interrupt_count[i] <= previous_interrupt_count[i]:
+#                        ok = False
+#                        break
+#                    self.gdb.p("$mie")
+#                    self.gdb.p("$mip")
+#                    self.gdb.p("$mstatus")
+#                    self.gdb.p("$priv")
+#                    self.gdb.p("buf", fmt="")
+#                    self.gdb.select_hart(h)
+#                    pc = self.gdb.p("$pc")
+#                    self.gdb.stepi()
+#                    stepped_pc = self.gdb.p("$pc")
+#                    assertNotEqual(pc, stepped_pc)
+#                previous_hart_count = hart_count
+#                previous_interrupt_count = interrupt_count
+#                if ok:
+#                    break
+#            else:
+#                assert False, \
+#                        "hart count or interrupt didn't increment as expected"
+
+class MulticoreRunAllHaltOne(GdbTest):
     compile_args = ("programs/multicore.c", "-DMULTICORE")
 
     def early_applicable(self):
         return len(self.target.harts) > 1
 
     def setup(self):
+        self.gdb.select_hart(self.target.harts[0])
         self.gdb.load()
         for hart in self.target.harts:
             self.gdb.select_hart(hart)
             self.gdb.p("$pc=_start")
 
     def test(self):
-        previous_hart_count = [0 for h in self.target.harts]
-        for _ in range(10):
+        if not self.gdb.one_hart_per_gdb():
+            return 'not_applicable'
+
+        # Run harts in reverse order
+        for h in reversed(self.target.harts):
+            self.gdb.select_hart(h)
             self.gdb.c(wait=False)
-            time.sleep(1)
-            self.gdb.interrupt()
-            self.gdb.p("buf", fmt="")
-            hart_count = self.gdb.p("hart_count")
-            for i, h in enumerate(self.target.harts):
-                assertGreater(hart_count[i], previous_hart_count[i])
-                self.gdb.select_hart(h)
-                pc = self.gdb.p("$pc")
-                self.gdb.stepi()
-                stepped_pc = self.gdb.p("$pc")
-                assertNotEqual(pc, stepped_pc)
-
-class StepTest(GdbTest):
+
+        self.gdb.interrupt()
+        # Give OpenOCD time to call poll() on both harts, which is what causes
+        # the bug.
+        time.sleep(1)
+        self.gdb.p("buf", fmt="")
+
+class MulticoreRtosSwitchActiveHartTest(GdbTest):
+    compile_args = ("programs/multicore.c", "-DMULTICORE")
+
+    def early_applicable(self):
+        return len(self.target.harts) > 1
+
+    def setup(self):
+        self.gdb.select_hart(self.target.harts[0])
+        self.gdb.load()
+        for hart in self.target.harts:
+            self.gdb.select_hart(hart)
+            self.gdb.p("$pc=_start")
+
+    def test(self):
+        if self.gdb.one_hart_per_gdb():
+            return 'not_applicable'
+
+        # Set breakpoint near '_start' label to increase the chances of a
+        # situation when all harts hit breakpoint immediately and
+        # simultaneously.
+        self.gdb.b("set_trap_handler")
+
+        # Check that all harts hit breakpoint one by one.
+        for _ in range(len(self.target.harts)):
+            output = self.gdb.c()
+            assertIn("hit Breakpoint", output)
+            assertIn("set_trap_handler", output)
+            assertNotIn("received signal SIGTRAP", output)
+
+class StepTest(GdbSingleHartTest):
     compile_args = ("programs/step.S", )
 
     def setup(self):
@@ -519,7 +713,30 @@ class StepTest(GdbTest):
             pc = self.gdb.p("$pc")
             assertEqual("%x" % (pc - main_address), "%x" % expected)
 
-class TriggerTest(GdbTest):
+class JumpHbreak(GdbSingleHartTest):
+    """'jump' resumes execution at location. Execution stops again immediately
+    if there is a breakpoint there.
+    That second line can be trouble."""
+    compile_args = ("programs/trigger.S", )
+
+    def early_applicable(self):
+        return self.hart.instruction_hardware_breakpoint_count >= 1
+
+    def setup(self):
+        self.gdb.load()
+        self.gdb.hbreak("main")
+        self.gdb.c()
+        self.gdb.command("delete 1")
+
+    def test(self):
+        self.gdb.b("read_loop")
+        self.gdb.command("hbreak just_before_read_loop")
+        output = self.gdb.command("jump just_before_read_loop")
+        assertRegexpMatches(output, r"Breakpoint \d, just_before_read_loop ")
+        output = self.gdb.c()
+        assertRegexpMatches(output, r"Breakpoint \d, read_loop ")
+
+class TriggerTest(GdbSingleHartTest):
     compile_args = ("programs/trigger.S", )
     def setup(self):
         self.gdb.load()
@@ -558,12 +775,18 @@ class TriggerLoadAddressInstant(TriggerTest):
         self.gdb.command("b just_before_read_loop")
         self.gdb.c()
         read_loop = self.gdb.p("&read_loop")
-        self.gdb.command("rwatch data")
+        read_again = self.gdb.p("&read_again")
+        data = self.gdb.p("&data")
+        self.gdb.command("rwatch *0x%x" % data)
         self.gdb.c()
         # Accept hitting the breakpoint before or after the load instruction.
         assertIn(self.gdb.p("$pc"), [read_loop, read_loop + 4])
         assertEqual(self.gdb.p("$a0"), self.gdb.p("&data"))
 
+        self.gdb.c()
+        assertIn(self.gdb.p("$pc"), [read_again, read_again + 4])
+        assertEqual(self.gdb.p("$a0"), self.gdb.p("&data"))
+
 # FIXME: Triggers aren't quite working yet
 #class TriggerStoreAddress(TriggerTest):
 #    def test(self):
@@ -581,8 +804,21 @@ class TriggerStoreAddressInstant(TriggerTest):
         self.gdb.command("b just_before_write_loop")
         self.gdb.c()
         write_loop = self.gdb.p("&write_loop")
-        self.gdb.command("watch data")
-        self.gdb.c()
+        data = self.gdb.p("&data")
+        self.gdb.command("watch *0x%x" % data)
+        output = self.gdb.c()
+        if "_exit (status=0)" in output:
+            # We ran to _exit. It looks as if we didn't hit the trigger at all.
+            # However this can be "correct" behavior. gdb's definition of
+            # "watch" is to run until the value in memory changes. To do this
+            # it reads the memory value when the trigger is set, and then when
+            # the halt happens. Because our triggers can fire just before the
+            # write happens, when gdb does this check the memory hasn't
+            # changed. So it silently resumes running.
+            # https://github.com/riscv/riscv-openocd/issues/295 tracks this
+            # problem. Until it's fixed, we're going to allow running to _exit.
+            return
+
         # Accept hitting the breakpoint before or after the store instruction.
         assertIn(self.gdb.p("$pc"), [write_loop, write_loop + 4])
         assertEqual(self.gdb.p("$a0"), self.gdb.p("&data"))
@@ -633,7 +869,7 @@ class TriggerDmode(TriggerTest):
         assertIn("clear_triggers", output)
         self.check_triggers((1<<6) | (1<<0), 0xfeedac00)
 
-class RegsTest(GdbTest):
+class RegsTest(GdbSingleHartTest):
     compile_args = ("programs/regs.S", )
     def setup(self):
         self.gdb.load()
@@ -710,17 +946,17 @@ class DownloadTest(GdbTest):
 
         self.binary = self.target.compile(self.hart, self.download_c.name,
                 "programs/checksum.c")
-        self.gdb.command("file %s" % self.binary)
+        self.gdb.global_command("file %s" % self.binary)
 
     def test(self):
         self.gdb.load()
+        self.parkOtherHarts()
         self.gdb.command("b _exit")
-        self.gdb.c(timeout=60)
+        self.gdb.c()
         assertEqual(self.gdb.p("status"), self.crc)
         os.unlink(self.download_c.name)
 
-# FIXME: PRIV isn't implemented in the current OpenOCD
-#class MprvTest(GdbTest):
+#class MprvTest(GdbSingleHartTest):
 #    compile_args = ("programs/mprv.S", )
 #    def setup(self):
 #        self.gdb.load()
@@ -732,56 +968,76 @@ class DownloadTest(GdbTest):
 #        self.gdb.interrupt()
 #        output = self.gdb.command("p/x *(int*)(((char*)&data)-0x80000000)")
 #        assertIn("0xbead", output)
-#
-#class PrivTest(GdbTest):
-#    compile_args = ("programs/priv.S", )
-#    def setup(self):
-#        # pylint: disable=attribute-defined-outside-init
-#        self.gdb.load()
-#
-#        misa = self.hart.misa
-#        self.supported = set()
-#        if misa & (1<<20):
-#            self.supported.add(0)
-#        if misa & (1<<18):
-#            self.supported.add(1)
-#        if misa & (1<<7):
-#            self.supported.add(2)
-#        self.supported.add(3)
-#
-#class PrivRw(PrivTest):
-#    def test(self):
-#        """Test reading/writing priv."""
-#        for privilege in range(4):
-#            self.gdb.p("$priv=%d" % privilege)
-#            self.gdb.stepi()
-#            actual = self.gdb.p("$priv")
-#            assertIn(actual, self.supported)
-#            if privilege in self.supported:
-#                assertEqual(actual, privilege)
-#
-#class PrivChange(PrivTest):
-#    def test(self):
-#        """Test that the core's privilege level actually changes."""
-#
-#        if 0 not in self.supported:
-#            return 'not_applicable'
-#
-#        self.gdb.b("main")
-#        self.gdb.c()
-#
-#        # Machine mode
-#        self.gdb.p("$priv=3")
-#        main_address = self.gdb.p("$pc")
-#        self.gdb.stepi()
-#        assertEqual("%x" % self.gdb.p("$pc"), "%x" % (main_address+4))
-#
-#        # User mode
-#        self.gdb.p("$priv=0")
-#        self.gdb.stepi()
-#        # Should have taken an exception, so be nowhere near main.
-#        pc = self.gdb.p("$pc")
-#        assertTrue(pc < main_address or pc > main_address + 0x100)
+
+class PrivTest(GdbSingleHartTest):
+    compile_args = ("programs/priv.S", )
+    def setup(self):
+        # pylint: disable=attribute-defined-outside-init
+        self.gdb.load()
+
+        misa = self.hart.misa
+        self.supported = set()
+        if misa & (1<<20):
+            self.supported.add(0)
+        if misa & (1<<18):
+            self.supported.add(1)
+        if misa & (1<<7):
+            self.supported.add(2)
+        self.supported.add(3)
+
+        # Disable physical memory protection by allowing U mode access to all
+        # memory.
+        try:
+            self.gdb.p("$pmpcfg0=0xf")  # TOR, R, W, X
+            self.gdb.p("$pmpaddr0=0x%x" %
+                    ((self.hart.ram + self.hart.ram_size) >> 2))
+        except testlib.CouldNotFetch:
+            # PMP registers are optional
+            pass
+
+        # Ensure Virtual Memory is disabled if applicable (SATP register is not
+        # reset)
+        try:
+            self.gdb.p("$satp=0")
+        except testlib.CouldNotFetch:
+            # SATP only exists if you have S mode.
+            pass
+
+class PrivRw(PrivTest):
+    def test(self):
+        """Test reading/writing priv."""
+        # Leave the PC at _start, where the first 4 instructions should be
+        # legal in any mode.
+        for privilege in range(4):
+            self.gdb.p("$priv=%d" % privilege)
+            self.gdb.stepi()
+            actual = self.gdb.p("$priv")
+            assertIn(actual, self.supported)
+            if privilege in self.supported:
+                assertEqual(actual, privilege)
+
+class PrivChange(PrivTest):
+    def test(self):
+        """Test that the core's privilege level actually changes."""
+
+        if 0 not in self.supported:
+            return 'not_applicable'
+
+        self.gdb.b("main")
+        self.gdb.c()
+
+        # Machine mode
+        self.gdb.p("$priv=3")
+        main_address = self.gdb.p("$pc")
+        self.gdb.stepi()
+        assertEqual("%x" % self.gdb.p("$pc"), "%x" % (main_address+4))
+
+        # User mode
+        self.gdb.p("$priv=0")
+        self.gdb.stepi()
+        # Should have taken an exception, so be nowhere near main.
+        pc = self.gdb.p("$pc")
+        assertTrue(pc < main_address or pc > main_address + 0x100)
 
 parsed = None
 def main():
@@ -800,9 +1056,7 @@ def main():
     global parsed   # pylint: disable=global-statement
     parsed = parser.parse_args()
     target = targets.target(parsed)
-
-    if parsed.xlen:
-        target.xlen = parsed.xlen
+    testlib.print_log_names = parsed.print_log_names
 
     module = sys.modules[__name__]