Re: [PATCH v3 3/3] tests/tcg: Add the PROT_NONE gdbstub test

["Alex Bennée" <alex.bennee@linaro.org>]

Ilya Leoshkevich <iii@linux.ibm.com> writes:

> On Mon, Jan 22, 2024 at 03:54:32PM +0000, Alex Bennée wrote:
>> Ilya Leoshkevich <iii@linux.ibm.com> writes:
>> 
>> > Make sure that qemu gdbstub, like gdbserver, allows reading from and
>> > writing to PROT_NONE pages.
>> >
>> > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
>> > ---
>> >  tests/tcg/multiarch/Makefile.target      |  9 +++++-
>> >  tests/tcg/multiarch/gdbstub/prot-none.py | 22 +++++++++++++
>> >  tests/tcg/multiarch/prot-none.c          | 40 ++++++++++++++++++++++++
>> >  3 files changed, 70 insertions(+), 1 deletion(-)
>> >  create mode 100644 tests/tcg/multiarch/gdbstub/prot-none.py
>> >  create mode 100644 tests/tcg/multiarch/prot-none.c
>
> [...]
>
>> > +def run_test():
>> > +    """Run through the tests one by one"""
>> > +    gdb.Breakpoint("break_here")
>> > +    gdb.execute("continue")
>> > +    val = gdb.parse_and_eval("*(char[2] *)q").string()
>> 
>> Better traceback:
>> 
>>   Breakpoint 1, break_here (q=0x400000802fff) at /home/alex/lsrc/qemu.git/tests/tcg/multiarch/prot-none.c:14
>>   14      }
>>   GDB Exception:
>>   Traceback (most recent call last):
>>     File "/home/alex/lsrc/qemu.git/tests/guest-debug/test_gdbstub.py", line 42, in main
>>       test()
>>     File "./tests/tcg/multiarch/gdbstub/prot-none.py", line 14, in run_test
>>       val = gdb.parse_and_eval("*(char[2] *)q").string()
>>             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>   gdb.MemoryError: Cannot access memory at address 0x400000802fff
>>   Python 3.11.2 (main, Mar 13 2023, 12:18:29) [GCC 12.2.0] on linux
>>   Type "help", "copyright", "credits" or "license" for more information.
>>   (InteractiveConsole)
>>   >>> 
>
> Thanks for the debug output. This shows that the feature being tested
> doesn't work (the value of `q` looks sane to me). May I ask what host
> distro is this? I tried on x86_64 Fedora 38 and x86_64 Ubuntu 22.04 so
> far, and the test was successful.

Debian Bookworm (x86_64) with gdb-multiarch installed.
>
> [...]

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro