Re: [PATCH] gdbstub: add support to Xfer:auxv:read: packet

[Lirong Yuan]

On Tue, Jul 21, 2020 at 12:50 PM Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Lirong Yuan <yuanzi@google.com> writes:
>
> > On Tue, Mar 31, 2020 at 12:20 AM Alex Bennée <alex.bennee@linaro.org> wrote:
> >>
> >>
> >> Lirong Yuan <yuanzi@google.com> writes:
> >>
> >> > On Mon, Mar 30, 2020 at 12:47 PM Alex Bennée <alex.bennee@linaro.org> 
> >> > wrote:
> >> >
> >> >>
> >> >> Lirong Yuan <yuanzi@google.com> writes:
> >> >>
> >> >> > On Sat, Mar 21, 2020 at 6:56 AM Alex Bennée <alex.bennee@linaro.org>
> >> >> wrote:
> >> >> >
> >> >> >>
> >> >> >> Lirong Yuan <yuanzi@google.com> writes:
> >> >> >>
> >> >> >> > On Fri, Mar 20, 2020 at 2:17 AM Alex Bennée 
> >> >> >> > <alex.bennee@linaro.org>
> >> >> >> wrote:
> >> >> >> <snip>
> >> >> >> >>
> >> >> >> >> Sorry I missed this on my radar. There was a minor re-factor of
> >> >> gdbstub
> >> >> >> >> that was just merged which will mean this patch needs a re-base to
> >> >> use
> >> >> >> >> g_string_* functions to expand stings.
> >> >> >> >>
> >> >> >> >> Also we have some simple gdbstub tests now - could we come up 
> >> >> >> >> with a
> >> >> >> >> multiarch gdbstub test to verify this is working properly?
> >> >> >> >>
> >> >> >> <snip>
> >> >> >> > For sure, I will re-base this patch to use g_string_* functions.
> >> >> >> >
> >> >> >> > Currently we are using qemu aarch64. I am not sure how to do this 
> >> >> >> > yet,
> >> >> >> but
> >> >> >> > I could try to add something to
> >> >> >> > https://github.com/qemu/qemu/tree/master/tests/tcg/aarch64/gdbstub
> >> >> >>
> >> >> >> If the auxv support is appropriate to all linux-user targets you can
> >> >> >> plumb it into the multiarch tests - you can even use the existing
> >> >> >> binaries.
> >> >> >>
> >> >> >> So you need:
> >> >> >>
> >> >> >>   - a stanza in the makefiles to launch the test (see
> >> >> >>     tests/tcg/aarch64/Makefile.target)
> >> >> >>
> >> >> >>   - a .py test script that manipulates gdbstub to check things are
> >> >> working
> >> >> >>
> >> >> >> So something like:
> >> >> >>
> >> >> >> .PHONY: gdbstub-foo-binary
> >> >> >> run-gdbstub-foo-binary: foo-binary
> >> >> >>         $(call run-test, $@, $(GDB_SCRIPT) \
> >> >> >>                 --gdb $(HAVE_GDB_BIN) \
> >> >> >>                 --qemu $(QEMU) --qargs "$(QEMU_OPTS)" \
> >> >> >>                 --bin $< --test 
> >> >> >> $(MULTIARCH_SRC)/gdbstub/test-foo.py, \
> >> >> >>         "basic gdbstub FOO support")
> >> >> >>
> >> >> >>
> >> >> >> >
> >> >> >> > Does this sound good?
> >> >> >>
> >> >> >> Hope that helps.
> >> >> >>
> >> >> >> >
> >> >> >> > Thanks!
> >> >> >> > Lirong
> >> >> >>
> >> >> >>
> >> >> >> --
> >> >> >> Alex Bennée
> >> >> >>
> >> >> >
> >> >> > Hi Alex,
> >> >> >
> >> >> > Thanks for the instructions, very helpful!
> >> >> >
> >> >> > I rebased this patch to use g_string_* functions, and the link to
> >> >> patchwork
> >> >> > is:
> >> >> > http://patchwork.ozlabs.org/patch/1264125/
> >> >> > Could you help take another look?
> >> >> >
> >> >> > Regarding testing, I looked at some instructions for running tests, 
> >> >> > e.g.
> >> >> > https://github.com/qemu/qemu/blob/master/docs/devel/testing.rst
> >> >> > https://wiki.qemu.org/Testing
> >> >> > However I still could not get the tests for aarch64 to run. Do you 
> >> >> > know
> >> >> how
> >> >> > to run the aarch64 or multi-arch tests?
> >> >>
> >> >> The aarch64 ones run with "make run-tcg-tests-aarch64-linux-user" add
> >> >> V=1 to see the details.
> >> >>
> >> >> > Also there aren't any existing gdb stub tests that try to read
> >> >> > uninterpreted bytes from the target’s special data area identified by 
> >> >> > a
> >> >> > keyword:
> >> >> >
> >> >> https://sourceware.org/gdb/current/onlinedocs/gdb/General-Query-Packets.html#qXfer-auxiliary-vector-read
> >> >> > I looked at some other gdb stub tests, but they did not seem to send 
> >> >> > any
> >> >> > queries:
> >> >> > https://github.com/qemu/qemu/tree/master/tests/tcg/aarch64/gdbstub
> >> >> > So I am not sure how to set up one for "Xfer:auxv:read:" packets...
> >> >> > Are there plans to add more tests for other packets like
> >> >> > "Xfer:features:read:"?
> >> >> > I'd be happy to add a test if there is an example of how to do it. :)
> >> >>
> >> >> What would you do from a normal gdb command line. At the very least you
> >> >> run the same command with gdb.execute(), e.g.:
> >> >>
> >> >>   gdb.execute("set confirm off")
> >> >>
> >> >> is the same as typing
> >> >>
> >> >>   set confirm off
> >> >>
> >> >> at the gdb command prompt.
> >> >>
> >> >> >
> >> >> > Thanks,
> >> >> > Lirong
> >> >>
> >> >>
> >> >> --
> >> >> Alex Bennée
> >> >>
> >> >
> >> > Hey Alex,
> >> >
> >> > I tried to run the test but they were skipped. Do you know if there's any
> >> > other flag that needs to be set?
> >> >
> >> > $ make run-tcg-tests-aarch64-linux-user
> >> > make[1]: Entering directory '/usr/local/google/home/yuanzi/qemu/slirp'
> >> > make[1]: Nothing to be done for 'all'.
> >> > make[1]: Leaving directory '/usr/local/google/home/yuanzi/qemu/slirp'
> >> >   BUILD   TCG tests for aarch64-linux-user
> >> >   BUILD   aarch64-linux-user guest-tests SKIPPED
> >> >   RUN     TCG tests for aarch64-linux-user
> >> >   RUN     tests for aarch64-linux-user SKIPPED
> >>
> >> Ahh you either need to have docker enabled or the aarch64 compilers in
> >> your path when you run configure so the test programs can be built. The
> >> details are in docs/devel/testing.rst
> >>
> >> > I don't think any command needs to be run. It should just send the query
> >> > automatically.
> >> > Could we assume that it will work the same in the test?
> >>
> >> If that is enough to exercise the code. Can we not validate the data 
> >> somehow?
> >>
> >>
> >> --
> >> Alex Bennée
> >
> > Hi Alex,
> >
> > Thanks for the suggestions! I just installed docker and ran the tests,
> > but got the following error messages for gdbstub tests:
> > $ make run-tcg-tests-aarch64-linux-user
> > ...
> > TEST    basic gdbstub support
> > warning: while parsing target description (at line 1): Target
> > description specified unknown architecture "aarch64"
> > warning: Could not load XML target description; ignoring
> > Truncated register 37 in remote 'g' packet
> > Traceback (most recent call last):
> >   File 
> > "/usr/local/google/home/yuanzi/Documents/gdbstub-patch/qemu/tests/tcg/multiarch/gdbstub/sha1.py",
> > line 68, in <module>
> >     if gdb.parse_and_eval('$pc') == 0:
> > gdb.error: No registers.
> >   TEST    basic gdbstub SVE support
> > warning: while parsing target description (at line 1): Target
> > description specified unknown architecture "aarch64"
> > warning: Could not load XML target description; ignoring
> > Truncated register 37 in remote 'g' packet
> >
> > I'm not sure if there is any additional setup needed to make those
> > tests pass. Do you know how to fix those errors?
>
> The error is because the gdb you have installed doesn't understand
> foreign architectures. The test should have skipped in this case so I',
> not sure why it causes it to fail.
>
> You can either ensure you have multiarch capable gdb (this is
> binutils-multiarch on debian for example) or build your own gdb and
> point at it with --gdb in configure.
>
> >
> > Thanks,
> > Lirong
>
>
> --
> Alex Bennée

Hmm I installed binutils-multiarch but it still did not work. The
error messages are the same as the previous ones.