crashpad/snapshot/crashpad_info_size_test_note.S

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// Copyright 2018 The Crashpad Authors
//
// 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.
// This note section is used on ELF platforms to give ElfImageReader a method
// of finding the instance of CrashpadInfo g_crashpad_info without requiring
// that symbol to be in the dynamic symbol table.
#include "util/misc/elf_note_types.h"
#include "util/misc/arm64_pac_bti.S"
// namespace crashpad {
// CrashpadInfo g_test_crashpad_info;
// } // namespace crashpad
#define TEST_CRASHPAD_INFO_SYMBOL _ZN8crashpad20g_test_crashpad_infoE
#define NOTE_ALIGN 4
// This section must be "a"llocated so that it appears in the final binary at
Reland "Use a relative address in .note.crashpad.info" This is a reland of 95e97a32eba4d505ab9591e683d2147c441eea48 Original change's description: > Use a relative address in .note.crashpad.info > > The desc value in the note is now the offset of CRASHPAD_INFO_SYMBOL > from desc. > > Making this note writable can trigger a linker error resulting in > the binary embedding .note.crashpad.info to be rejected by the > kernel during program loading. > > The error was observed with: > GNU ld (GNU Binutils for Debian) 2.30 > clang version 4.0.1-10 (tags/RELEASE_401/final) > Debian 4.17.17-1rodete2 > > When the note is made writable, crashpad_snapshot_test contains two > PT_LOAD segments which map to the same page. > > LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000 > 0x0000000000000258 0x0000000000000258 R 0x200000 > LOAD 0x0000000000000258 0x0000000000000258 0x0000000000000258 > 0x00000000002b84d8 0x00000000002b8950 RWE 0x200000 > > Executing this binary with the execv system call triggers a segfault > during program loading (an error can't be returned because the original > process vm has already been discarded). > > I suspect (I haven't set up a debuggable kernel) the failure occurs > while attempting to map the second load segment because its virtual > address, 0x258, is in the same page as the first load segment. > https://elixir.bootlin.com/linux/v4.17.17/source/fs/binfmt_elf.c#L380 > > The linker normally produces consecutive load segments where the second > segment is loaded 0x200000 bytes after the first, which I think is the > maximum expected page size. Modifying the test executable to load the > second segment at 0x1258 (4096 byte page size) allows program loading > to succeed (but of course crashes after control is given to it). > > Bug: crashpad:260 > Change-Id: I2b9f1e66e98919138baef3da991a9710bd970dc4 > Reviewed-on: https://chromium-review.googlesource.com/c/1292232 > Reviewed-by: Scott Graham <scottmg@chromium.org> > Reviewed-by: Mark Mentovai <mark@chromium.org> > Commit-Queue: Joshua Peraza <jperaza@chromium.org> Bug: crashpad:260 Change-Id: I66713de84cc26c9119e0454d19c9c189263fe054 Reviewed-on: https://chromium-review.googlesource.com/c/1318066 Commit-Queue: Joshua Peraza <jperaza@chromium.org> Reviewed-by: Mark Mentovai <mark@chromium.org> Reviewed-by: Scott Graham <scottmg@chromium.org>
2018-11-06 13:19:06 -08:00
// runtime. The reference to TEST_CRASHPAD_INFO_SYMBOL uses an offset relative
// to this note to avoid making this note writable, which triggers a bug in
// GNU ld, or adding text relocations which require the target system to allow
// making text segments writable. https://crbug.com/crashpad/260.
.section .note.crashpad.info,"a",%note
.balign NOTE_ALIGN
.type info_size_test_note, %object
info_size_test_note:
.long name_end - name // namesz
.long desc_end - desc // descsz
.long CRASHPAD_ELF_NOTE_TYPE_CRASHPAD_INFO // type
name:
.asciz CRASHPAD_ELF_NOTE_NAME
name_end:
.balign NOTE_ALIGN
desc:
#if defined(__LP64__)
Reland "Use a relative address in .note.crashpad.info" This is a reland of 95e97a32eba4d505ab9591e683d2147c441eea48 Original change's description: > Use a relative address in .note.crashpad.info > > The desc value in the note is now the offset of CRASHPAD_INFO_SYMBOL > from desc. > > Making this note writable can trigger a linker error resulting in > the binary embedding .note.crashpad.info to be rejected by the > kernel during program loading. > > The error was observed with: > GNU ld (GNU Binutils for Debian) 2.30 > clang version 4.0.1-10 (tags/RELEASE_401/final) > Debian 4.17.17-1rodete2 > > When the note is made writable, crashpad_snapshot_test contains two > PT_LOAD segments which map to the same page. > > LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000 > 0x0000000000000258 0x0000000000000258 R 0x200000 > LOAD 0x0000000000000258 0x0000000000000258 0x0000000000000258 > 0x00000000002b84d8 0x00000000002b8950 RWE 0x200000 > > Executing this binary with the execv system call triggers a segfault > during program loading (an error can't be returned because the original > process vm has already been discarded). > > I suspect (I haven't set up a debuggable kernel) the failure occurs > while attempting to map the second load segment because its virtual > address, 0x258, is in the same page as the first load segment. > https://elixir.bootlin.com/linux/v4.17.17/source/fs/binfmt_elf.c#L380 > > The linker normally produces consecutive load segments where the second > segment is loaded 0x200000 bytes after the first, which I think is the > maximum expected page size. Modifying the test executable to load the > second segment at 0x1258 (4096 byte page size) allows program loading > to succeed (but of course crashes after control is given to it). > > Bug: crashpad:260 > Change-Id: I2b9f1e66e98919138baef3da991a9710bd970dc4 > Reviewed-on: https://chromium-review.googlesource.com/c/1292232 > Reviewed-by: Scott Graham <scottmg@chromium.org> > Reviewed-by: Mark Mentovai <mark@chromium.org> > Commit-Queue: Joshua Peraza <jperaza@chromium.org> Bug: crashpad:260 Change-Id: I66713de84cc26c9119e0454d19c9c189263fe054 Reviewed-on: https://chromium-review.googlesource.com/c/1318066 Commit-Queue: Joshua Peraza <jperaza@chromium.org> Reviewed-by: Mark Mentovai <mark@chromium.org> Reviewed-by: Scott Graham <scottmg@chromium.org>
2018-11-06 13:19:06 -08:00
.quad TEST_CRASHPAD_INFO_SYMBOL - desc
#else
Reland "Use a relative address in .note.crashpad.info" This is a reland of 95e97a32eba4d505ab9591e683d2147c441eea48 Original change's description: > Use a relative address in .note.crashpad.info > > The desc value in the note is now the offset of CRASHPAD_INFO_SYMBOL > from desc. > > Making this note writable can trigger a linker error resulting in > the binary embedding .note.crashpad.info to be rejected by the > kernel during program loading. > > The error was observed with: > GNU ld (GNU Binutils for Debian) 2.30 > clang version 4.0.1-10 (tags/RELEASE_401/final) > Debian 4.17.17-1rodete2 > > When the note is made writable, crashpad_snapshot_test contains two > PT_LOAD segments which map to the same page. > > LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000 > 0x0000000000000258 0x0000000000000258 R 0x200000 > LOAD 0x0000000000000258 0x0000000000000258 0x0000000000000258 > 0x00000000002b84d8 0x00000000002b8950 RWE 0x200000 > > Executing this binary with the execv system call triggers a segfault > during program loading (an error can't be returned because the original > process vm has already been discarded). > > I suspect (I haven't set up a debuggable kernel) the failure occurs > while attempting to map the second load segment because its virtual > address, 0x258, is in the same page as the first load segment. > https://elixir.bootlin.com/linux/v4.17.17/source/fs/binfmt_elf.c#L380 > > The linker normally produces consecutive load segments where the second > segment is loaded 0x200000 bytes after the first, which I think is the > maximum expected page size. Modifying the test executable to load the > second segment at 0x1258 (4096 byte page size) allows program loading > to succeed (but of course crashes after control is given to it). > > Bug: crashpad:260 > Change-Id: I2b9f1e66e98919138baef3da991a9710bd970dc4 > Reviewed-on: https://chromium-review.googlesource.com/c/1292232 > Reviewed-by: Scott Graham <scottmg@chromium.org> > Reviewed-by: Mark Mentovai <mark@chromium.org> > Commit-Queue: Joshua Peraza <jperaza@chromium.org> Bug: crashpad:260 Change-Id: I66713de84cc26c9119e0454d19c9c189263fe054 Reviewed-on: https://chromium-review.googlesource.com/c/1318066 Commit-Queue: Joshua Peraza <jperaza@chromium.org> Reviewed-by: Mark Mentovai <mark@chromium.org> Reviewed-by: Scott Graham <scottmg@chromium.org>
2018-11-06 13:19:06 -08:00
.long TEST_CRASHPAD_INFO_SYMBOL - desc
#endif // __LP64__
desc_end:
.size info_size_test_note, .-info_size_test_note