Re: [kvm-unit-tests RFC 1/2] s390x: Add guest snippet support

[Janosch Frank <frankja@linux.ibm.com>]

On 6/21/21 2:32 PM, Thomas Huth wrote:
> On 21/06/2021 14.19, Janosch Frank wrote:
>> On 6/21/21 12:10 PM, Thomas Huth wrote:
>>> On 20/05/2021 11.47, Janosch Frank wrote:
>>>> Snippets can be used to easily write and run guest (SIE) tests.
>>>> The snippet is linked into the test binaries and can therefore be
>>>> accessed via a ptr.
>>>>
>>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>>> ---
>>>>    .gitignore                |  2 ++
>>>>    s390x/Makefile            | 28 ++++++++++++++++++---
>>>>    s390x/snippets/c/cstart.S | 13 ++++++++++
>>>>    s390x/snippets/c/flat.lds | 51 +++++++++++++++++++++++++++++++++++++++
>>>>    4 files changed, 91 insertions(+), 3 deletions(-)
>>>>    create mode 100644 s390x/snippets/c/cstart.S
>>>>    create mode 100644 s390x/snippets/c/flat.lds
>>>>
>>>> diff --git a/.gitignore b/.gitignore
>>>> index 784cb2dd..29d3635b 100644
>>>> --- a/.gitignore
>>>> +++ b/.gitignore
>>>> @@ -22,3 +22,5 @@ cscope.*
>>>>    /api/dirty-log
>>>>    /api/dirty-log-perf
>>>>    /s390x/*.bin
>>>> +/s390x/snippets/*/*.bin
>>>> +/s390x/snippets/*/*.gbin
>>>> diff --git a/s390x/Makefile b/s390x/Makefile
>>>> index 8de926ab..fe267011 100644
>>>> --- a/s390x/Makefile
>>>> +++ b/s390x/Makefile
>>>> @@ -75,11 +75,33 @@ OBJDIRS += lib/s390x
>>>>    asmlib = $(TEST_DIR)/cstart64.o $(TEST_DIR)/cpu.o
>>>>    
>>>>    FLATLIBS = $(libcflat)
>>>> -%.elf: %.o $(FLATLIBS) $(SRCDIR)/s390x/flat.lds $(asmlib)
>>>> +
>>>> +SNIPPET_DIR = $(TEST_DIR)/snippets
>>>> +
>>>> +# C snippets that need to be linked
>>>> +snippets-c =
>>>> +
>>>> +# ASM snippets that are directly compiled and converted to a *.gbin
>>>> +snippets-a =
>>>
>>> Could you please call this snippets-s instead of ...-a ? The -a suffix looks
>>> like an archive to me otherwise.
>>
>> Sure
>>
>>>
>>>> +snippets = $(snippets-a)$(snippets-c)
>>>
>>> Shouldn't there be a space between the two?
>>
>> Yes, already fixed that a long while ago
>> I thought I had sent out a new version already, maybe that was an
>> illusion as I can't seem to find it right now.
>>
>>>
>>>> +snippets-o += $(patsubst %.gbin,%.o,$(snippets))
>>>> +
>>>> +$(snippets-a): $(snippets-o) $(FLATLIBS)
>>>> +	$(OBJCOPY) -O binary $(patsubst %.gbin,%.o,$@) $@
>>>> +	$(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $@ $@
>>>> +
>>>> +$(snippets-c): $(snippets-o) $(SNIPPET_DIR)/c/cstart.o  $(FLATLIBS)
>>>> +	$(CC) $(LDFLAGS) -o $@ -T $(SNIPPET_DIR)/c/flat.lds \
>>>> +		$(filter %.o, $^) $(FLATLIBS)
>>>> +	$(OBJCOPY) -O binary $@ $@
>>>> +	$(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $@ $@
>>>> +
>>>> +%.elf: $(snippets) %.o $(FLATLIBS) $(SRCDIR)/s390x/flat.lds $(asmlib)
>>>>    	$(CC) $(CFLAGS) -c -o $(@:.elf=.aux.o) \
>>>>    		$(SRCDIR)/lib/auxinfo.c -DPROGNAME=\"$@\"
>>>>    	$(CC) $(LDFLAGS) -o $@ -T $(SRCDIR)/s390x/flat.lds \
>>>> -		$(filter %.o, $^) $(FLATLIBS) $(@:.elf=.aux.o)
>>>> +		$(filter %.o, $^) $(FLATLIBS) $(snippets) $(@:.elf=.aux.o)
>>>
>>> Does this link the snippets into all elf files? ... wouldn't it be better to
>>> restrict it somehow to the files that really need them?
>>
>> Yes it does.
>> I'd like to avoid having to specify a makefile rule for every test that
>> uses snippets as we already have more than the mvpg one in the queue.
>>
>> So I'm having Steffen looking into a solution for this problem. My first
>> idea was to bring the used snippets into the unittests.cfg but I
>> disliked that we then would have compile instructions in another file.
>> Maybe there's a way to include that into the makefile in a clever way?
> 
> I haven't tried, but maybe you could replace the $(snippets) in the last 
> line with
> 
>   $(wildcard snippets/$@.gbin)
> 
> or something similar?

That starts falling apart when multiple tests use the same snippet, no?


> 
>   Thomas
>