Re: [PATCH v2 0/9] Add MTE stubs for aarch64 user mode

[Gustavo Romero <gustavo.romero@linaro.org>]

Hi Alex,

On 6/17/24 6:50 AM, Alex Bennée wrote:
> Gustavo Romero <gustavo.romero@linaro.org> writes:
> 
>> Hi Alex,
>>
>> On 6/14/24 12:49 PM, Alex Bennée wrote:
>>> Gustavo Romero <gustavo.romero@linaro.org> writes:
>>>
>>>> This patchset adds the stubs necessary to support GDB memory tagging
>>>> commands on QEMU aarch64 user mode.
>>>>
>>>> These new stubs handle the qIsAddressTagged, qMemTag, and QMemTag
>>>> packets, which allow GDB memory tagging subcommands 'check',
>>>> 'print-allocation-tag', and 'set-allocation-tag' to work. The remaining
>>>> memory tagging commands ('print-logical-tag' and 'with-logical-tag')
>>>> will also work, but they don't rely on any stub because they perform
>>>> local operations.
>>>>
>>>> Since the memory tagging stubs are not common to all architectures, this
>>>> patchset also introduces three functions: gdb_extend_qsupported_features,
>>>> gdb_extend_query_table, and gdb_extend_set_table. These functions can be
>>>> used to extend the target-specific 'qSupported' feature string and the
>>>> handlers for the 'q' (query) and 'Q' (set) packets. These new functions
>>>> are used to add the MTE stubs for the aarch64 gdbstub.
>>>>    Note that this patchset requires a GDB that supports the
>>>> qIsAddressTagged packet (recently added to GDB), so the gdbstub MTE
>>>> tests introduced by it must be run using GDB's master branch, since the
>>>> GDB in the distros hasn't picked up the change yet.
>>>>
>>>> Once GDB is built and installed locally, the tests can be exercised, for
>>>> example, this way:
>>>>
>>>> make GDB=~/.local/bin/gdb run-tcg-tests-aarch64-linux-user -j 32
>>> It looks like there might be some BSD build failures as well:
>>>     https://gitlab.com/stsquad/qemu/-/pipelines/1332635371/failures
>>
>> I fixed the build for the BSD target in v3, however I think that the GDB in
>> the test containers need to be bumped to GDB 15 so the MTE tests can pass,
>> because support for IsAddressTagged packet is necessary. GDB 15 branch
>> is created by it's not released yet, so I don't know to proceed..
> 
> Two potential approaches, you could extend the configure segment:
> 
> if test -n "$gdb_bin"; then
>      gdb_version=$($gdb_bin --version | head -n 1)
>      if version_ge ${gdb_version##* } 9.1; then
>          gdb_arches=$($python "$source_path/scripts/probe-gdb-support.py" $gdb_bin)
>      else
>          gdb_bin=""
>      fi
> fi
> 
> and set a variable exported to config-host.mak to then test in the tcg
> test makefiles.

Done in v4. Thanks for the suggestions!


Cheers,
Gustavo

> Or you could implement a gdb-version-test command in
> tests/tcg/Makefile.target which you could use like the existing
> cc-test/cc-option commands to extend config-cc.mak and use that to gate
> the tests.