crashpad/snapshot/elf/elf_image_reader_test_note.S
Scott Graham 7faa2ef898 Get CrashpadInfo address via a .note, rather than dynamic symtab
Embeds the address of g_crashpad_info into a .note section (which is
readable by the generic code to read notes in ElfImageReader).
Unfortunately because the note section is in libclient.a, it would
normally be dropped at link time.  To avoid that, GetCrashpadInfo() has
a reference *back* to that section, which in turn forces the linker to
include it, allowing the note reader to find it at runtime.

Previously, it was necessary to have the embedder of "client" figure out
how to cause `g_crashpad_info` to appear in the final module's dynamic
symbol table.  With this new approach, there's no manual configuration
necessary, as it's not necessary for the symbol to be exported.

This is currently only implemented in the Linux module reader (and I
believe the current set of enabled tests aren't exercising it?) but it
will also be done this way for the Fuchsia implementation of
ModuleSnapshot.

Bug: crashpad:196
Change-Id: I599db5903bc98303130d11ad850ba9ceed3b801a
Reviewed-on: https://chromium-review.googlesource.com/912284
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
2018-02-15 19:02:12 +00:00

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ArmAsm

// Copyright 2017 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "util/misc/elf_note_types.h"
#define NOTE_ALIGN 4
.section .note.crashpad.test,"a",%note
.balign NOTE_ALIGN
.type testnote, %object
testnote:
.long name_end - name // namesz
.long desc_end - desc // descsz
.long CRASHPAD_ELF_NOTE_TYPE_SNAPSHOT_TEST // type
name:
.asciz CRASHPAD_ELF_NOTE_NAME
name_end:
.balign NOTE_ALIGN
desc:
.long 42
desc_end:
.size testnote, .-testnote