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

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

On 5/25/21 6:44 PM, Claudio Imbrenda wrote:
> On Thu, 20 May 2021 09:47:29 +0000
> Janosch Frank <frankja@linux.ibm.com> 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 =
>> +
>> +snippets = $(snippets-a)$(snippets-c)
>                           ↑↑
> I'm not a Makefile expert, but, don't you need a space between the two
> variable expansions?
> 

Yup, I already fixed that one

>> +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)
> 
> I would keep the %.o as the first in the list>
>>  	$(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)
> 
> so all the snippets are always baked in every test?

Currently yes.
Do you have better ideas?

> 
>> $(@:.elf=.aux.o) $(RM) $(@:.elf=.aux.o)
>>  	@chmod a-x $@
>>  
>> @@ -93,7 +115,7 @@ FLATLIBS = $(libcflat)
>>  	$(GENPROTIMG) --host-key-document $(HOST_KEY_DOCUMENT)
>> --no-verify --image $< -o $@ 
>>  arch_clean: asm_offsets_clean
>> -	$(RM) $(TEST_DIR)/*.{o,elf,bin} $(TEST_DIR)/.*.d
>> lib/s390x/.*.d
>> +	$(RM) $(TEST_DIR)/*.{o,elf,bin}
>> $(SNIPPET_DIR)/c/*.{o,elf,bin,gbin} $(SNIPPET_DIR)/.*.d
>> $(TEST_DIR)/.*.d lib/s390x/.*.d generated-files = $(asm-offsets)
>>  $(tests:.elf=.o) $(asmlib) $(cflatobjs): $(generated-files)
>> diff --git a/s390x/snippets/c/cstart.S b/s390x/snippets/c/cstart.S
>> new file mode 100644
>> index 00000000..02a3338b
>> --- /dev/null
>> +++ b/s390x/snippets/c/cstart.S
>> @@ -0,0 +1,13 @@
>> +#include <asm/sigp.h>
>> +
>> +.section .init
>> +	.globl start
>> +start:
>> +	/* XOR all registers with themselves to clear them fully. */
>> +	.irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
>> +	xgr \i,\i
>> +	.endr
>> +	/* 0x3000 is the stack page for now */
>> +	lghi	%r15, 0x4000
>> +	brasl	%r14, main
>> +	sigp    %r1, %r0, SIGP_STOP
>> diff --git a/s390x/snippets/c/flat.lds b/s390x/snippets/c/flat.lds
>> new file mode 100644
>> index 00000000..5e707325
>> --- /dev/null
>> +++ b/s390x/snippets/c/flat.lds
>> @@ -0,0 +1,51 @@
>> +SECTIONS
>> +{
>> +	.lowcore : {
>> +		/*
>> +		 * Initial short psw for disk boot, with 31 bit
>> addressing for
>> +		 * non z/Arch environment compatibility and the
>> instruction
>> +		 * address 0x10000 (cstart64.S .init).
>> +		 */
>> +		. = 0;
>> +		 LONG(0x00080000)
>> +		 LONG(0x80004000)
>> +		 /* Restart new PSW for booting via PSW restart. */
>> +		 . = 0x1a0;
>> +		 QUAD(0x0000000180000000)
>> +		 QUAD(0x0000000000004000)
>> +	}
>> +	. = 0x4000;
>> +	.text : {
>> +		*(.init)
>> +		*(.text)
>> +		*(.text.*)
>> +	}
>> +	. = ALIGN(64K);
>> +	etext = .;
>> +	.opd : { *(.opd) }
>> +	. = ALIGN(16);
>> +	.dynamic : {
>> +		dynamic_start = .;
>> +		*(.dynamic)
>> +	}
>> +	.dynsym : {
>> +		dynsym_start = .;
>> +		*(.dynsym)
>> +	}
>> +	.rela.dyn : { *(.rela*) }
>> +	. = ALIGN(16);
>> +	.data : {
>> +		*(.data)
>> +		*(.data.rel*)
>> +	}
>> +	. = ALIGN(16);
>> +	.rodata : { *(.rodata) *(.rodata.*) }
>> +	. = ALIGN(16);
>> +	__bss_start = .;
>> +	.bss : { *(.bss) }
>> +	__bss_end = .;
>> +	. = ALIGN(64K);
>> +	edata = .;
>> +	. += 64K;
>> +	. = ALIGN(64K);
>> +}
>