[PATCH 00/23] Memory Tagging Support + AArch64 Linux implementation
Luis Machado
luis.machado@linaro.org
Fri Jul 17 12:33:24 GMT 2020
On 7/16/20 1:49 PM, Alan Hayward wrote:
>
>
>> On 15 Jul 2020, at 20:44, Luis Machado <luis.machado@linaro.org> wrote:
>>
>> This patch series implements general memory tagging support for GDB, as well
>> as an implementation for AArch64 Linux.
>>
>> Memory tagging improves memory safety by tagging various parts of memory and
>> raising exceptions when the allocation tag (the one associated with a range of
>> memory addresses) does not match the logical tag contained in a pointer that is
>> used to access the memory area.
>>
>> We already have an implementation of such a mechanism for sparc64 (ADI), but
>> it is target-specific and not exposed to the rest of GDB. This series aims to
>> make the infrastructure available to other targets that may wish to support
>> their specific memory tagging approaches. For AArch64 Linux this is called
>> MTE (Memory Tagging Extensions).
>>
>> The series is split into a set that deals with generic changes to GDB's
>> infrastructure (target methods, gdbarch hooks and remote packets), a set that
>> implements support for AArch64 Linux and one last set that implements new
>> commands, updates the documentation and adds tests.
>>
>> The goal is to make it so the architecture independent parts of GDB don't
>> need to interpret tag formats, given the formats are likely different
>> for each architecture. For this reason, GDB will handle tags as a sequence of
>> bytes and will not assume a particular format.
>>
>> The architecture-specific code can handle the sequence of bytes appropriately.
>
> I’ve reviewed earlier versions of this series, and my comments have been applied.
> I’ve still taken a look through each patch in this latest series, and I’m mostly
> happy now. Instead of replying to each patch in turn, these are my bulk set of
> comments:
>
> [PATCH 01/23] New target methods for memory tagging support
> [PATCH 02/23] New gdbarch memory tagging hooks
> - Looks good to me.
>
> [PATCH 03/23] Add GDB-side remote target support for memory tagging
> [PATCH 04/23] Unit testing for GDB-side remote memory tagging handling
> [PATCH 05/23] GDBserver remote packet support for memory tagging
> [PATCH 06/23] Unit tests for gdbserver memory tagging remote packets
> [PATCH 07/23] Documentation for memory tagging remote packets
> - Looks ok, but I’m not that familiar with the remote packet interface.
> Worth someone else looking over.
>
> [PATCH 08/23] AArch64: Add MTE CPU feature check support
> [PATCH 09/23] AArch64: Add target description/feature for MTE registers
> [PATCH 10/23] AArch64: Add MTE register set support for GDB and gdbserver
> [PATCH 11/23] AArch64: Add MTE ptrace requests
> [PATCH 12/23] AArch64: Implement memory tagging target methods for AArch64
> [PATCH 13/23] Refactor parsing of /proc/<pid>/smaps
> [PATCH 14/23] AArch64: Implement the memory tagging gdbarch hooks
> [PATCH 15/23] AArch64: Add unit testing for logical tag set/get operations
> [PATCH 16/23] AArch64: Report tag violation error information
> [PATCH 17/23] AArch64: Add gdbserver MTE support
> - These all Look good to me. My only concern here is that the Linux kernel support
> is a WIP. But given GDB is the main user of these interfaces, and that you’ve been
> reviewing the Linux patches, then I’m happy as long as they have all been tested
> together.
I have exercised the GDB series with Catalin's kernel series under QEMU.
So the GDB changes match what the kernel is exposing right now.
>
> [PATCH 18/23] New mtag commands
> [PATCH 19/23] Documentation for the new mtag commands
> - I’m happy with the new commands. But would like to know what others think, and
> I’m not familiar enough with the implementation of the commands to do a detailed
> review.
Same here. The idea is to provide some basic commands as a first step.
Other commands can be added as needed.
>
> [PATCH 20/23] Extend "x" and "print" commands to support memory tagging
> - Am I correct in thinking that p/x cannot cause a segfault? (we don’t want
> one to happen)
They can run into a segfault if, for example, you invoke a function that
segfaults. But they won't trigger one if you attempt to access variables
using invalid tags. Those will only happen when the process itself
causes a tag violation.
GDB strips the top byte of the pointer on memory operations as well, so
the addresses will have no tags in most cases.
>
> [PATCH 21/23] Document new "x" and "print" memory tagging extensions
> [PATCH 22/23] Add NEWS entry.
> - Looks good (assuming the commands aren’t changed)
>
>
>>
>> Luis Machado (23):
>> New target methods for memory tagging support
>> New gdbarch memory tagging hooks
>> Add GDB-side remote target support for memory tagging
>> Unit testing for GDB-side remote memory tagging handling
>> GDBserver remote packet support for memory tagging
>> Unit tests for gdbserver memory tagging remote packets
>> Documentation for memory tagging remote packets
>> AArch64: Add MTE CPU feature check support
>> AArch64: Add target description/feature for MTE registers
>> AArch64: Add MTE register set support for GDB and gdbserver
>> AArch64: Add MTE ptrace requests
>> AArch64: Implement memory tagging target methods for AArch64
>> Refactor parsing of /proc/<pid>/smaps
>> AArch64: Implement the memory tagging gdbarch hooks
>> AArch64: Add unit testing for logical tag set/get operations
>> AArch64: Report tag violation error information
>> AArch64: Add gdbserver MTE support
>> New mtag commands
>> Documentation for the new mtag commands
>> Extend "x" and "print" commands to support memory tagging
>> Document new "x" and "print" memory tagging extensions
>> Add NEWS entry.
>> Add memory tagging testcases
>>
>> gdb/Makefile.in | 3 +
>> gdb/NEWS | 32 ++
>> gdb/aarch64-linux-nat.c | 121 ++++++-
>> gdb/aarch64-linux-tdep.c | 330 ++++++++++++++++-
>> gdb/aarch64-tdep.c | 40 ++-
>> gdb/aarch64-tdep.h | 12 +-
>> gdb/arch-utils.c | 50 +++
>> gdb/arch-utils.h | 23 ++
>> gdb/arch/aarch64-mte-linux.c | 70 ++++
>> gdb/arch/aarch64-mte-linux.h | 66 ++++
>> gdb/arch/aarch64.c | 7 +-
>> gdb/arch/aarch64.h | 7 +-
>> gdb/configure.nat | 3 +-
>> gdb/configure.tgt | 1 +
>> gdb/doc/gdb.texinfo | 174 ++++++++-
>> gdb/features/Makefile | 1 +
>> gdb/features/aarch64-mte.c | 14 +
>> gdb/features/aarch64-mte.xml | 11 +
>> gdb/gdbarch.c | 137 ++++++++
>> gdb/gdbarch.h | 53 +++
>> gdb/gdbarch.sh | 36 ++
>> gdb/linux-tdep.c | 356 ++++++++++++-------
>> gdb/linux-tdep.h | 4 +
>> gdb/nat/aarch64-mte-linux-ptrace.c | 200 +++++++++++
>> gdb/nat/aarch64-mte-linux-ptrace.h | 50 +++
>> gdb/printcmd.c | 468 ++++++++++++++++++++++++-
>> gdb/remote.c | 230 ++++++++++++
>> gdb/target-delegates.c | 84 +++++
>> gdb/target.h | 25 ++
>> gdb/testsuite/gdb.arch/aarch64-mte.c | 107 ++++++
>> gdb/testsuite/gdb.arch/aarch64-mte.exp | 371 ++++++++++++++++++++
>> gdb/testsuite/gdb.base/memtag.c | 22 ++
>> gdb/testsuite/gdb.base/memtag.exp | 64 ++++
>> gdb/testsuite/lib/gdb.exp | 16 +
>> gdb/valprint.h | 1 +
>> gdbserver/Makefile.in | 1 +
>> gdbserver/configure.srv | 2 +
>> gdbserver/linux-aarch64-ipa.cc | 8 +-
>> gdbserver/linux-aarch64-low.cc | 89 ++++-
>> gdbserver/linux-aarch64-tdesc.cc | 10 +-
>> gdbserver/linux-aarch64-tdesc.h | 3 +-
>> gdbserver/remote-utils.cc | 40 +--
>> gdbserver/remote-utils.h | 2 +
>> gdbserver/server.cc | 214 +++++++++++
>> gdbserver/server.h | 3 +
>> gdbserver/target.cc | 20 ++
>> gdbserver/target.h | 17 +
>> gdbsupport/rsp-low.cc | 2 +-
>> include/elf/common.h | 3 +
>> 49 files changed, 3421 insertions(+), 182 deletions(-)
>> create mode 100644 gdb/arch/aarch64-mte-linux.c
>> create mode 100644 gdb/arch/aarch64-mte-linux.h
>> create mode 100644 gdb/features/aarch64-mte.c
>> create mode 100644 gdb/features/aarch64-mte.xml
>> create mode 100644 gdb/nat/aarch64-mte-linux-ptrace.c
>> create mode 100644 gdb/nat/aarch64-mte-linux-ptrace.h
>> create mode 100644 gdb/testsuite/gdb.arch/aarch64-mte.c
>> create mode 100644 gdb/testsuite/gdb.arch/aarch64-mte.exp
>> create mode 100644 gdb/testsuite/gdb.base/memtag.c
>> create mode 100644 gdb/testsuite/gdb.base/memtag.exp
>>
>> --
>> 2.17.1
>>
>
More information about the Gdb-patches
mailing list