Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 596 insertions, 0 deletions

diff --git a/js/src/gdb/mozilla/unwind.py b/js/src/gdb/mozilla/unwind.py
new file mode 100644
index 0000000000..8dd0ec8311
--- /dev/null
+++ b/js/src/gdb/mozilla/unwind.py
@@ -0,0 +1,596 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# mozilla/unwind.py --- unwinder and frame filter for SpiderMonkey
+
+import gdb
+import gdb.types
+from gdb.FrameDecorator import FrameDecorator
+import platform
+
+# For ease of use in Python 2, we use "long" instead of "int"
+# everywhere.
+try:
+    long
+except NameError:
+    long = int
+
+# The Python 3 |map| built-in works lazily, but in Python 2 we need
+# itertools.imap to get this.
+try:
+    from itertools import imap
+except ImportError:
+    imap = map
+
+_have_unwinder = True
+try:
+    from gdb.unwinder import Unwinder
+except ImportError:
+    _have_unwinder = False
+    # We need something here; it doesn't matter what as no unwinder
+    # will ever be instantiated.
+    Unwinder = object
+
+
+def debug(something):
+    # print("@@ " + something)
+    pass
+
+
+# Maps frametype enum base names to corresponding class.
+SizeOfFramePrefix = {
+    "FrameType::IonJS": "ExitFrameLayout",
+    "FrameType::BaselineJS": "JitFrameLayout",
+    "FrameType::BaselineStub": "BaselineStubFrameLayout",
+    "FrameType::IonStub": "JitStubFrameLayout",
+    "FrameType::CppToJSJit": "JitFrameLayout",
+    "FrameType::WasmToJSJit": "JitFrameLayout",
+    "FrameType::JSJitToWasm": "JitFrameLayout",
+    "FrameType::Rectifier": "RectifierFrameLayout",
+    "FrameType::IonAccessorIC": "IonAccessorICFrameLayout",
+    "FrameType::IonICCall": "IonICCallFrameLayout",
+    "FrameType::Exit": "ExitFrameLayout",
+    "FrameType::Bailout": "JitFrameLayout",
+}
+
+
+# We cannot have semi-colon as identifier names, so use a colon instead,
+# and forward the name resolution to the type cache class.
+class UnwinderTypeCacheFrameType(object):
+    def __init__(self, tc):
+        self.tc = tc
+
+    def __getattr__(self, name):
+        return self.tc.__getattr__("FrameType::" + name)
+
+
+class UnwinderTypeCache(object):
+    # All types and symbols that we need are attached to an object that we
+    # can dispose of as needed.
+
+    def __init__(self):
+        self.d = None
+        self.frame_enum_names = {}
+        self.frame_class_types = {}
+
+    # We take this bizarre approach to defer trying to look up any
+    # symbols until absolutely needed.  Without this, the loading
+    # approach taken by the gdb-tests would cause spurious exceptions.
+    def __getattr__(self, name):
+        if self.d is None:
+            self.initialize()
+        if name == "frame_type":
+            return UnwinderTypeCacheFrameType(self)
+        return self.d[name]
+
+    def value(self, name):
+        return long(gdb.lookup_symbol(name)[0].value())
+
+    def jit_value(self, name):
+        return self.value("js::jit::" + name)
+
+    def initialize(self):
+        self.d = {}
+        self.d["FRAMETYPE_MASK"] = (1 << self.jit_value("FRAMETYPE_BITS")) - 1
+        self.d["FRAMESIZE_SHIFT"] = self.jit_value("FRAMESIZE_SHIFT")
+        self.d["FRAME_HEADER_SIZE_SHIFT"] = self.jit_value("FRAME_HEADER_SIZE_SHIFT")
+        self.d["FRAME_HEADER_SIZE_MASK"] = self.jit_value("FRAME_HEADER_SIZE_MASK")
+
+        self.compute_frame_info()
+        commonFrameLayout = gdb.lookup_type("js::jit::CommonFrameLayout")
+        self.d["typeCommonFrameLayout"] = commonFrameLayout
+        self.d["typeCommonFrameLayoutPointer"] = commonFrameLayout.pointer()
+        self.d["per_tls_context"] = gdb.lookup_global_symbol("js::TlsContext")
+
+        self.d["void_starstar"] = gdb.lookup_type("void").pointer().pointer()
+
+        jitframe = gdb.lookup_type("js::jit::JitFrameLayout")
+        self.d["jitFrameLayoutPointer"] = jitframe.pointer()
+
+        self.d["CalleeToken_Function"] = self.jit_value("CalleeToken_Function")
+        self.d["CalleeToken_FunctionConstructing"] = self.jit_value(
+            "CalleeToken_FunctionConstructing"
+        )
+        self.d["CalleeToken_Script"] = self.jit_value("CalleeToken_Script")
+        self.d["JSFunction"] = gdb.lookup_type("JSFunction").pointer()
+        self.d["JSScript"] = gdb.lookup_type("JSScript").pointer()
+        self.d["Value"] = gdb.lookup_type("JS::Value")
+
+        self.d["SOURCE_SLOT"] = self.value("js::ScriptSourceObject::SOURCE_SLOT")
+        self.d["NativeObject"] = gdb.lookup_type("js::NativeObject").pointer()
+        self.d["HeapSlot"] = gdb.lookup_type("js::HeapSlot").pointer()
+        self.d["ScriptSource"] = gdb.lookup_type("js::ScriptSource").pointer()
+
+        # ProcessExecutableMemory, used to identify if a pc is in the section
+        # pre-allocated by the JIT.
+        self.d["MaxCodeBytesPerProcess"] = self.jit_value("MaxCodeBytesPerProcess")
+        self.d["execMemory"] = gdb.lookup_symbol("::execMemory")[0].value()
+
+    # Compute maps related to jit frames.
+    def compute_frame_info(self):
+        t = gdb.lookup_type("enum js::jit::FrameType")
+        for field in t.fields():
+            # Strip off "js::jit::", remains: "FrameType::*".
+            name = field.name[9:]
+            enumval = long(field.enumval)
+            self.d[name] = enumval
+            self.frame_enum_names[enumval] = name
+            class_type = gdb.lookup_type("js::jit::" + SizeOfFramePrefix[name])
+            self.frame_class_types[enumval] = class_type.pointer()
+
+
+class FrameSymbol(object):
+    "A symbol/value pair as expected from gdb frame decorators."
+
+    def __init__(self, sym, val):
+        self.sym = sym
+        self.val = val
+
+    def symbol(self):
+        return self.sym
+
+    def value(self):
+        return self.val
+
+
+class JitFrameDecorator(FrameDecorator):
+    """This represents a single JIT frame for the purposes of display.
+    That is, the frame filter creates instances of this when it sees a
+    JIT frame in the stack."""
+
+    def __init__(self, base, info, cache):
+        super(JitFrameDecorator, self).__init__(base)
+        self.info = info
+        self.cache = cache
+
+    def _decode_jitframe(self, this_frame):
+        calleetoken = long(this_frame["calleeToken_"])
+        tag = calleetoken & 3
+        calleetoken = calleetoken ^ tag
+        function = None
+        script = None
+        if (
+            tag == self.cache.CalleeToken_Function
+            or tag == self.cache.CalleeToken_FunctionConstructing
+        ):
+            fptr = gdb.Value(calleetoken).cast(self.cache.JSFunction)
+            try:
+                atom = fptr["atom_"]
+                if atom:
+                    function = str(atom)
+            except gdb.MemoryError:
+                function = "(could not read function name)"
+            script = fptr["u"]["scripted"]["s"]["script_"]
+        elif tag == self.cache.CalleeToken_Script:
+            script = gdb.Value(calleetoken).cast(self.cache.JSScript)
+        return {"function": function, "script": script}
+
+    def function(self):
+        if self.info["name"] is None:
+            return FrameDecorator.function(self)
+        name = self.info["name"]
+        result = "<<" + name
+        # If we have a frame, we can extract the callee information
+        # from it for display here.
+        this_frame = self.info["this_frame"]
+        if this_frame is not None:
+            if gdb.types.has_field(this_frame.type.target(), "calleeToken_"):
+                function = self._decode_jitframe(this_frame)["function"]
+                if function is not None:
+                    result = result + " " + function
+        return result + ">>"
+
+    def filename(self):
+        this_frame = self.info["this_frame"]
+        if this_frame is not None:
+            if gdb.types.has_field(this_frame.type.target(), "calleeToken_"):
+                script = self._decode_jitframe(this_frame)["script"]
+                if script is not None:
+                    obj = script["sourceObject_"]["value"]
+                    # Verify that this is a ScriptSource object.
+                    # FIXME should also deal with wrappers here.
+                    nativeobj = obj.cast(self.cache.NativeObject)
+                    # See bug 987069 and despair.  At least this
+                    # approach won't give exceptions.
+                    class_name = nativeobj["group_"]["value"]["clasp_"]["name"].string(
+                        "ISO-8859-1"
+                    )
+                    if class_name != "ScriptSource":
+                        return FrameDecorator.filename(self)
+                    scriptsourceobj = (nativeobj + 1).cast(self.cache.HeapSlot)[
+                        self.cache.SOURCE_SLOT
+                    ]
+                    scriptsource = scriptsourceobj["value"]["asBits_"] << 1
+                    scriptsource = scriptsource.cast(self.cache.ScriptSource)
+                    return scriptsource["filename_"]["mTuple"]["mFirstA"].string()
+        return FrameDecorator.filename(self)
+
+    def frame_args(self):
+        this_frame = self.info["this_frame"]
+        if this_frame is None:
+            return FrameDecorator.frame_args(self)
+        if not gdb.types.has_field(this_frame.type.target(), "numActualArgs_"):
+            return FrameDecorator.frame_args(self)
+        # See if this is a function call.
+        if self._decode_jitframe(this_frame)["function"] is None:
+            return FrameDecorator.frame_args(self)
+        # Construct and return an iterable of all the arguments.
+        result = []
+        num_args = long(this_frame["numActualArgs_"])
+        # Sometimes we see very large values here, so truncate it to
+        # bypass the damage.
+        if num_args > 10:
+            num_args = 10
+        args_ptr = (this_frame + 1).cast(self.cache.Value.pointer())
+        for i in range(num_args + 1):
+            # Synthesize names, since there doesn't seem to be
+            # anything better to do.
+            if i == 0:
+                name = "this"
+            else:
+                name = "arg%d" % i
+            result.append(FrameSymbol(name, args_ptr[i]))
+        return result
+
+
+class SpiderMonkeyFrameFilter(object):
+    "A frame filter for SpiderMonkey."
+
+    # |state_holder| is either None, or an instance of
+    # SpiderMonkeyUnwinder.  If the latter, then this class will
+    # reference the |unwinder_state| attribute to find the current
+    # unwinder state.
+    def __init__(self, cache, state_holder):
+        self.name = "SpiderMonkey"
+        self.enabled = True
+        self.priority = 100
+        self.state_holder = state_holder
+        self.cache = cache
+
+    def maybe_wrap_frame(self, frame):
+        if self.state_holder is None or self.state_holder.unwinder_state is None:
+            return frame
+        base = frame.inferior_frame()
+        info = self.state_holder.unwinder_state.get_frame(base)
+        if info is None:
+            return frame
+        return JitFrameDecorator(frame, info, self.cache)
+
+    def filter(self, frame_iter):
+        return imap(self.maybe_wrap_frame, frame_iter)
+
+
+class SpiderMonkeyFrameId(object):
+    "A frame id class, as specified by the gdb unwinder API."
+
+    def __init__(self, sp, pc):
+        self.sp = sp
+        self.pc = pc
+
+
+class UnwinderState(object):
+    """This holds all the state needed during a given unwind.  Each time a
+    new unwind is done, a new instance of this class is created.  It
+    keeps track of all the state needed to unwind JIT frames.  Note that
+    this class is not directly instantiated.
+
+    This is a base class, and must be specialized for each target
+    architecture, both because we need to use arch-specific register
+    names, and because entry frame unwinding is arch-specific.
+    See https://sourceware.org/bugzilla/show_bug.cgi?id=19286 for info
+    about the register name issue.
+
+    Each subclass must define SP_REGISTER, PC_REGISTER, and
+    SENTINEL_REGISTER (see x64UnwinderState for info); and implement
+    unwind_entry_frame_registers."""
+
+    def __init__(self, typecache):
+        self.next_sp = None
+        self.next_type = None
+        self.activation = None
+        # An unwinder instance is specific to a thread.  Record the
+        # selected thread for later verification.
+        self.thread = gdb.selected_thread()
+        self.frame_map = {}
+        self.typecache = typecache
+
+    # If the given gdb.Frame was created by this unwinder, return the
+    # corresponding informational dictionary for the frame.
+    # Otherwise, return None.  This is used by the frame filter to
+    # display extra information about the frame.
+    def get_frame(self, frame):
+        sp = long(frame.read_register(self.SP_REGISTER))
+        if sp in self.frame_map:
+            return self.frame_map[sp]
+        return None
+
+    # Add information about a frame to the frame map.  This map is
+    # queried by |self.get_frame|.  |sp| is the frame's stack pointer,
+    # and |name| the frame's type as a string, e.g. "FrameType::Exit".
+    def add_frame(self, sp, name=None, this_frame=None):
+        self.frame_map[long(sp)] = {"name": name, "this_frame": this_frame}
+
+    # See whether |pc| is claimed by the Jit.
+    def is_jit_address(self, pc):
+        execMem = self.typecache.execMemory
+        base = long(execMem["base_"])
+        length = self.typecache.MaxCodeBytesPerProcess
+
+        # If the base pointer is null, then no memory got allocated yet.
+        if long(base) == 0:
+            return False
+
+        # If allocated, then we allocated MaxCodeBytesPerProcess.
+        return base <= pc and pc < base + length
+
+    # Check whether |self| is valid for the selected thread.
+    def check(self):
+        return gdb.selected_thread() is self.thread
+
+    # Essentially js::TlsContext.get().
+    def get_tls_context(self):
+        return self.typecache.per_tls_context.value()["mValue"]
+
+    # |common| is a pointer to a CommonFrameLayout object.  Return a
+    # tuple (local_size, header_size, frame_type), where |size| is the
+    # integer size of the previous frame's locals; |header_size| is
+    # the size of this frame's header; and |frame_type| is an integer
+    # representing the previous frame's type.
+    def unpack_descriptor(self, common):
+        value = long(common["descriptor_"])
+        local_size = value >> self.typecache.FRAMESIZE_SHIFT
+        header_size = (
+            value >> self.typecache.FRAME_HEADER_SIZE_SHIFT
+        ) & self.typecache.FRAME_HEADER_SIZE_MASK
+        header_size = header_size * self.typecache.void_starstar.sizeof
+        frame_type = long(value & self.typecache.FRAMETYPE_MASK)
+        if frame_type == self.typecache.frame_type.CppToJSJit:
+            # Trampoline-x64.cpp pushes a JitFrameLayout object, but
+            # the stack pointer is actually adjusted as if a
+            # CommonFrameLayout object was pushed.
+            header_size = self.typecache.typeCommonFrameLayout.sizeof
+        return (local_size, header_size, frame_type)
+
+    # Create a new frame for gdb.  This makes a new unwind info object
+    # and fills it in, then returns it.  It also registers any
+    # pertinent information with the frame filter for later display.
+    #
+    # |pc| is the PC from the pending frame
+    # |sp| is the stack pointer to use
+    # |frame| points to the CommonFrameLayout object
+    # |frame_type| is a integer, one of the |enum FrameType| values,
+    # describing the current frame.
+    # |pending_frame| is the pending frame (see the gdb unwinder
+    # documentation).
+    def create_frame(self, pc, sp, frame, frame_type, pending_frame):
+        # Make a frame_id that claims that |frame| is sort of like a
+        # frame pointer for this frame.
+        frame_id = SpiderMonkeyFrameId(frame, pc)
+
+        # Read the frame layout object to find the next such object.
+        # This lets us unwind the necessary registers for the next
+        # frame, and also update our internal state to match.
+        common = frame.cast(self.typecache.typeCommonFrameLayoutPointer)
+        next_pc = common["returnAddress_"]
+        (local_size, header_size, next_type) = self.unpack_descriptor(common)
+        next_sp = frame + header_size + local_size
+
+        # Compute the type of the next oldest frame's descriptor.
+        this_class_type = self.typecache.frame_class_types[frame_type]
+        this_frame = frame.cast(this_class_type)
+
+        # Register this frame so the frame filter can find it.  This
+        # is registered using SP because we don't have any other good
+        # approach -- you can't get the frame id from a gdb.Frame.
+        # https://sourceware.org/bugzilla/show_bug.cgi?id=19800
+        frame_name = self.typecache.frame_enum_names[frame_type]
+        self.add_frame(sp, name=frame_name, this_frame=this_frame)
+
+        # Update internal state for the next unwind.
+        self.next_sp = next_sp
+        self.next_type = next_type
+
+        unwind_info = pending_frame.create_unwind_info(frame_id)
+        unwind_info.add_saved_register(self.PC_REGISTER, next_pc)
+        unwind_info.add_saved_register(self.SP_REGISTER, next_sp)
+        # FIXME it would be great to unwind any other registers here.
+        return unwind_info
+
+    # Unwind an "ordinary" JIT frame.  This is used for JIT frames
+    # other than enter and exit frames.  Returns the newly-created
+    # unwind info for gdb.
+    def unwind_ordinary(self, pc, pending_frame):
+        return self.create_frame(
+            pc, self.next_sp, self.next_sp, self.next_type, pending_frame
+        )
+
+    # Unwind an exit frame.  Returns None if this cannot be done;
+    # otherwise returns the newly-created unwind info for gdb.
+    def unwind_exit_frame(self, pc, pending_frame):
+        if self.activation == 0:
+            # Reached the end of the list.
+            return None
+        elif self.activation is None:
+            cx = self.get_tls_context()
+            self.activation = cx["jitActivation"]["value"]
+        else:
+            self.activation = self.activation["prevJitActivation_"]
+
+        packedExitFP = self.activation["packedExitFP_"]
+        if packedExitFP == 0:
+            return None
+
+        exit_sp = pending_frame.read_register(self.SP_REGISTER)
+        frame_type = self.typecache.frame_type.Exit
+        return self.create_frame(pc, exit_sp, packedExitFP, frame_type, pending_frame)
+
+    # A wrapper for unwind_entry_frame_registers that handles
+    # architecture-independent boilerplate.
+    def unwind_entry_frame(self, pc, pending_frame):
+        sp = self.next_sp
+        # Notify the frame filter.
+        self.add_frame(sp, name="FrameType::CppToJSJit")
+        # Make an unwind_info for the per-architecture code to fill in.
+        frame_id = SpiderMonkeyFrameId(sp, pc)
+        unwind_info = pending_frame.create_unwind_info(frame_id)
+        self.unwind_entry_frame_registers(sp, unwind_info)
+        self.next_sp = None
+        self.next_type = None
+        return unwind_info
+
+    # The main entry point that is called to try to unwind a JIT frame
+    # of any type.  Returns None if this cannot be done; otherwise
+    # returns the newly-created unwind info for gdb.
+    def unwind(self, pending_frame):
+        pc = pending_frame.read_register(self.PC_REGISTER)
+
+        # If the jit does not claim this address, bail.  GDB defers to our
+        # unwinder by default, but we don't really want that kind of power.
+        if not self.is_jit_address(long(pc)):
+            return None
+
+        if self.next_sp is not None:
+            if self.next_type == self.typecache.frame_type.CppToJSJit:
+                return self.unwind_entry_frame(pc, pending_frame)
+            return self.unwind_ordinary(pc, pending_frame)
+        # Maybe we've found an exit frame.  FIXME I currently don't
+        # know how to identify these precisely, so we'll just hope for
+        # the time being.
+        return self.unwind_exit_frame(pc, pending_frame)
+
+
+class x64UnwinderState(UnwinderState):
+    "The UnwinderState subclass for x86-64."
+
+    SP_REGISTER = "rsp"
+    PC_REGISTER = "rip"
+
+    # A register unique to this architecture, that is also likely to
+    # have been saved in any frame.  The best thing to use here is
+    # some arch-specific name for PC or SP.
+    SENTINEL_REGISTER = "rip"
+
+    # Must be in sync with Trampoline-x64.cpp:generateEnterJIT.  Note
+    # that rip isn't pushed there explicitly, but rather by the
+    # previous function's call.
+    PUSHED_REGS = ["r15", "r14", "r13", "r12", "rbx", "rbp", "rip"]
+
+    # Fill in the unwound registers for an entry frame.
+    def unwind_entry_frame_registers(self, sp, unwind_info):
+        sp = sp.cast(self.typecache.void_starstar)
+        # Skip the "result" push.
+        sp = sp + 1
+        for reg in self.PUSHED_REGS:
+            data = sp.dereference()
+            sp = sp + 1
+            unwind_info.add_saved_register(reg, data)
+            if reg == "rbp":
+                unwind_info.add_saved_register(self.SP_REGISTER, sp)
+
+
+class SpiderMonkeyUnwinder(Unwinder):
+    """The unwinder object.  This provides the "user interface" to the JIT
+    unwinder, and also handles constructing or destroying UnwinderState
+    objects as needed."""
+
+    # A list of all the possible unwinders.  See |self.make_unwinder|.
+    UNWINDERS = [x64UnwinderState]
+
+    def __init__(self, typecache):
+        super(SpiderMonkeyUnwinder, self).__init__("SpiderMonkey")
+        self.typecache = typecache
+        self.unwinder_state = None
+
+        # Disabled by default until we figure out issues in gdb.
+        self.enabled = False
+        gdb.write(
+            "SpiderMonkey unwinder is disabled by default, to enable it type:\n"
+            + "\tenable unwinder .* SpiderMonkey\n"
+        )
+        # Some versions of gdb did not flush the internal frame cache
+        # when enabling or disabling an unwinder.  This was fixed in
+        # the same release of gdb that added the breakpoint_created
+        # event.
+        if not hasattr(gdb.events, "breakpoint_created"):
+            gdb.write("\tflushregs\n")
+
+        # We need to invalidate the unwinder state whenever the
+        # inferior starts executing.  This avoids having a stale
+        # cache.
+        gdb.events.cont.connect(self.invalidate_unwinder_state)
+        assert self.test_sentinels()
+
+    def test_sentinels(self):
+        # Self-check.
+        regs = {}
+        for unwinder in self.UNWINDERS:
+            if unwinder.SENTINEL_REGISTER in regs:
+                return False
+            regs[unwinder.SENTINEL_REGISTER] = 1
+        return True
+
+    def make_unwinder(self, pending_frame):
+        # gdb doesn't provide a good way to find the architecture.
+        # See https://sourceware.org/bugzilla/show_bug.cgi?id=19399
+        # So, we look at each known architecture and see if the
+        # corresponding "unique register" is known.
+        for unwinder in self.UNWINDERS:
+            try:
+                pending_frame.read_register(unwinder.SENTINEL_REGISTER)
+            except Exception:
+                # Failed to read the register, so let's keep going.
+                # This is more fragile than it might seem, because it
+                # fails if the sentinel register wasn't saved in the
+                # previous frame.
+                continue
+            return unwinder(self.typecache)
+        return None
+
+    def __call__(self, pending_frame):
+        if self.unwinder_state is None or not self.unwinder_state.check():
+            self.unwinder_state = self.make_unwinder(pending_frame)
+        if not self.unwinder_state:
+            return None
+        return self.unwinder_state.unwind(pending_frame)
+
+    def invalidate_unwinder_state(self, *args, **kwargs):
+        self.unwinder_state = None
+
+
+def register_unwinder(objfile):
+    """Register the unwinder and frame filter with |objfile|.  If |objfile|
+    is None, register them globally."""
+
+    type_cache = UnwinderTypeCache()
+    unwinder = None
+    # This currently only works on Linux, due to parse_proc_maps.
+    if _have_unwinder and platform.system() == "Linux":
+        unwinder = SpiderMonkeyUnwinder(type_cache)
+        gdb.unwinder.register_unwinder(objfile, unwinder, replace=True)
+    # We unconditionally register the frame filter, because at some
+    # point we'll add interpreter frame filtering.
+    filt = SpiderMonkeyFrameFilter(type_cache, unwinder)
+    if objfile is None:
+        objfile = gdb
+    objfile.frame_filters[filt.name] = filt