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}
52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
// 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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#include "heap-constants.h"
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#include "src/common/globals.h"
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namespace d = v8::debug_helper;
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namespace v8_debug_helper_internal {
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std::string FindKnownObject(uintptr_t address, const d::Roots& roots) {
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uintptr_t containing_page = address & ~i::kPageAlignmentMask;
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uintptr_t offset_in_page = address & i::kPageAlignmentMask;
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// If there's a match with a known root, then search only that page.
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if (containing_page == roots.map_space) {
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return FindKnownObjectInMapSpace(offset_in_page);
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}
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if (containing_page == roots.old_space) {
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return FindKnownObjectInOldSpace(offset_in_page);
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}
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if (containing_page == roots.read_only_space) {
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return FindKnownObjectInReadOnlySpace(offset_in_page);
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}
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// For any unknown roots, compile a list of things this object might be.
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std::string result;
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if (roots.map_space == 0) {
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std::string sub_result = FindKnownObjectInMapSpace(offset_in_page);
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if (!sub_result.empty()) {
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result += "maybe " + sub_result;
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}
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}
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if (roots.old_space == 0) {
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std::string sub_result = FindKnownObjectInOldSpace(offset_in_page);
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if (!sub_result.empty()) {
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result = (result.empty() ? "" : result + ", ") + "maybe " + sub_result;
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}
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}
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if (roots.read_only_space == 0) {
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std::string sub_result = FindKnownObjectInReadOnlySpace(offset_in_page);
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if (!sub_result.empty()) {
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result = (result.empty() ? "" : result + ", ") + "maybe " + sub_result;
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}
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}
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return result;
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}
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} // namespace v8_debug_helper_internal
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