0921e8f28b
This is a reland of 517ab73fd7
Updates since original: now compressed pointers passed to the function
GetObjectProperties are required to be sign-extended. Previously, the
function allowed zero-extended values, but that led to ambiguity on
pointers like 0x88044919: is it compressed or is the heap range actually
centered on 0x100000000?
Original change's description:
> Add postmortem debugging helper library
>
> This change begins to implement the functionality described in
> https://docs.google.com/document/d/1evHnb1uLlSbvHAAsmOXyc25x3uh1DjgNa8u1RHvwVhk/edit#
> for investigating V8 state in crash dumps.
>
> This change adds a new library, v8_debug_helper, for providing platform-
> agnostic assistance with postmortem debugging. This library can be used
> by extensions built for debuggers such as WinDbg or lldb. Its public API
> is described by debug-helper.h; currently the only method it exposes is
> GetObjectProperties, but we'd like to add more functionality over time.
> The API surface is restricted to plain C-style structs and pointers, so
> that it's easy to link from a debugger extension built with a different
> toolchain.
>
> This change also adds a new cctest file to exercise some basic
> interaction with the new library.
>
> The API function GetObjectProperties takes an object pointer (which
> could be compressed, or weak, or a SMI), and returns a string
> description of the object and a list of properties the object contains.
> For now, the list of properties is entirely based on Torque object
> definitions, but we expect to add custom properties in future updates so
> that it can be easier to make sense of complex data structures such as
> dictionaries.
>
> GetObjectProperties does several things that are intended to generate
> somewhat useful results even in cases where memory may be corrupt or
> unavailable:
> - The caller may optionally provide a type string which will be used if
> the memory for the object's Map is inaccessible.
> - All object pointers are compared against the list of known objects
> generated by mkgrokdump. The caller may optionally provide the
> pointers for the first pages of various heap spaces, to avoid spurious
> matches. If those pointers are not provided, then any matches are
> prefixed with "maybe" in the resulting description string, such as
> "maybe UndefinedValue (0x4288000341 <Oddball>)".
>
> Bug: v8:9376
>
> Change-Id: Iebf3cc2dea3133c7811bcefcdf38d9458b02fded
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1628012
> Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Michael Stanton <mvstanton@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62882}
Bug: v8:9376
Change-Id: I866a1cc9d4c34bfe10c7b98462451fe69763cf3f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1717090
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#63008}
64 lines
2.1 KiB
Python
64 lines
2.1 KiB
Python
#!/usr/bin/env python
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# Copyright 2019 the V8 project authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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"""This program writes a C++ file that can be used to look up whether a given
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address matches known object locations. The first argument is the directory
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containing the file v8heapconst.py; the second argument is the output .cc file.
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"""
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import sys
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sys.path.insert(0, sys.argv[1])
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import v8heapconst
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out = """
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#include <cstdint>
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#include <string>
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namespace v8_debug_helper_internal {
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"""
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def iterate_objects(target_space, camel_space_name):
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global out
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result = []
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for (space, offset), (instance_type, name) in v8heapconst.KNOWN_MAPS.items():
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if space == target_space:
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result.append((offset, name))
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for (space, offset), name in v8heapconst.KNOWN_OBJECTS.items():
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if space == target_space:
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result.append((offset, name))
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out = out + '\nstd::string FindKnownObjectIn' + camel_space_name \
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+ '(uintptr_t offset) {\n switch (offset) {\n'
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for offset, name in result:
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out = out + ' case ' + str(offset) + ': return "' + name + '";\n'
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out = out + ' default: return "";\n }\n}\n'
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iterate_objects('map_space', 'MapSpace')
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iterate_objects('read_only_space', 'ReadOnlySpace')
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iterate_objects('old_space', 'OldSpace')
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def iterate_maps(target_space, camel_space_name):
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global out
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out = out + '\nint FindKnownMapInstanceTypeIn' + camel_space_name \
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+ '(uintptr_t offset) {\n switch (offset) {\n'
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for (space, offset), (instance_type, name) in v8heapconst.KNOWN_MAPS.items():
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if space == target_space:
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out = out + ' case ' + str(offset) + ': return ' + str(instance_type) \
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+ ';\n'
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out = out + ' default: return -1;\n }\n}\n'
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iterate_maps('map_space', 'MapSpace')
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iterate_maps('read_only_space', 'ReadOnlySpace')
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out = out + '\n}\n'
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try:
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with open(sys.argv[2], "r") as out_file:
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if out == out_file.read():
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sys.exit(0) # No modification needed.
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except:
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pass # File probably doesn't exist; write it.
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with open(sys.argv[2], "w") as out_file:
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out_file.write(out)
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