Re: [kvm-unit-tests PATCH 3/6] s390x: Add a linker script to assembly snippets

[Janosch Frank <frankja@xxxxxxxxxxxxx>]

On 7/29/22 16:17, Steffen Eiden wrote:
> On 7/29/22 10:26, Janosch Frank wrote:
> > A linker script has a few benefits:
> > - We can easily define a lowcore and load the snippet from 0x0 instead
> > of 0x4000 which makes asm snippets behave like c snippets
> > - We can easily define an invalid PGM new PSW to ensure an exit on a
> > guest PGM
> >
> > As we gain another step and file extension by linking, a comment
> > explains which file extensions are generated and why.
> >
> > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> > ---
> >    lib/s390x/snippet.h |  3 +--
> >    s390x/Makefile      | 16 +++++++++++++---
> >    s390x/mvpg-sie.c    |  2 +-
> >    s390x/pv-diags.c    |  6 +++---
> >    4 files changed, 18 insertions(+), 9 deletions(-)
> >
> > diff --git a/lib/s390x/snippet.h b/lib/s390x/snippet.h
> > index b17b2a4c..57045994 100644
> > --- a/lib/s390x/snippet.h
> > +++ b/lib/s390x/snippet.h
> > @@ -32,8 +32,7 @@
> >    
> >    #define SNIPPET_PV_TWEAK0	0x42UL
> >    #define SNIPPET_PV_TWEAK1	0UL
> > -#define SNIPPET_OFF_C		0
> > -#define SNIPPET_OFF_ASM		0x4000
> > +#define SNIPPET_UNPACK_OFF	0
> >    
> >    
> >    /*
> > diff --git a/s390x/Makefile b/s390x/Makefile
> > index ee34a1d7..9a0b48e2 100644
> > --- a/s390x/Makefile
> > +++ b/s390x/Makefile
> > @@ -122,6 +122,13 @@ else
> >    snippet-hdr-obj =
> >    endif
> >    
> > +# Each snippet will generate the following files (in order): \
> > +  *.o is a snippet that has been compiled \
> > +  *.ol is a snippet that has been linked \
> > +  *.gbin is a snippet that has been converted to binary \
> > +  *.gobj is the final format after converting the binary into a elf file again, \
> > +  it will be linked into the tests
> > +
> >    # the asm/c snippets %.o have additional generated files as dependencies
> >    $(SNIPPET_DIR)/asm/%.o: $(SNIPPET_DIR)/asm/%.S $(asm-offsets)
> >    	$(CC) $(CFLAGS) -c -nostdlib -o $@ $<
> > @@ -129,8 +136,11 @@ $(SNIPPET_DIR)/asm/%.o: $(SNIPPET_DIR)/asm/%.S $(asm-offsets)
> >    $(SNIPPET_DIR)/c/%.o: $(SNIPPET_DIR)/c/%.c $(asm-offsets)
> >    	$(CC) $(CFLAGS) -c -nostdlib -o $@ $<
> >    
> > -$(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.o
> > -	$(OBJCOPY) -O binary -j ".rodata" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $(patsubst %.gbin,%.o,$@) $@
> > +$(SNIPPET_DIR)/asm/%.ol: $(SNIPPET_DIR)/asm/%.o
> > +	$(CC) $(LDFLAGS) -o $@ -T $(SRCDIR)/s390x/snippets/asm/flat.lds $<
>
> I think you forgot to include that linker script in the patch.
> Or did I miss anything?
>
> you can also use the $(SNIPPET_DIR) variable instead of searching for
> that directory yourself.

Right on both cases, I'll fix that...

> > +
> > +$(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.ol
> > +	$(OBJCOPY) -O binary -j ".rodata" -j ".lowcore" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $< $@
> >    	truncate -s '%4096' $@
> >    
> >    $(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_lib) $(FLATLIBS)
> > @@ -139,7 +149,7 @@ $(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_lib) $(FLATLIBS)
> >    	truncate -s '%4096' $@
> >    
> >    $(SNIPPET_DIR)/asm/%.hdr: $(SNIPPET_DIR)/asm/%.gbin $(HOST_KEY_DOCUMENT)
> > -	$(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x4000,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
> > +	$(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x0,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
> >    
> >    $(SNIPPET_DIR)/c/%.hdr: $(SNIPPET_DIR)/c/%.gbin $(HOST_KEY_DOCUMENT)
> >    	$(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x0,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
> > diff --git a/s390x/mvpg-sie.c b/s390x/mvpg-sie.c
> > index 46a2edb6..99f4859b 100644
> > --- a/s390x/mvpg-sie.c
> > +++ b/s390x/mvpg-sie.c
> > @@ -87,7 +87,7 @@ static void setup_guest(void)
> >    
> >    	snippet_setup_guest(&vm, false);
> >    	snippet_init(&vm, SNIPPET_NAME_START(c, mvpg_snippet),
> > -		     SNIPPET_LEN(c, mvpg_snippet), SNIPPET_OFF_C);
> > +		     SNIPPET_LEN(c, mvpg_snippet), SNIPPET_UNPACK_OFF);
> >    
> >    	/* Enable MVPG interpretation as we want to test KVM and not ourselves */
> >    	vm.sblk->eca = ECA_MVPGI;
> > diff --git a/s390x/pv-diags.c b/s390x/pv-diags.c
> > index 9ced68c7..5165937a 100644
> > --- a/s390x/pv-diags.c
> > +++ b/s390x/pv-diags.c
> > @@ -28,7 +28,7 @@ static void test_diag_500(void)
> >    
> >    	snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_500),
> >    			SNIPPET_HDR_START(asm, snippet_pv_diag_500),
> > -			size_gbin, size_hdr, SNIPPET_OFF_ASM);
> > +			size_gbin, size_hdr, SNIPPET_UNPACK_OFF);
> >    
> >    	sie(&vm);
> >    	report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 &&
> > @@ -83,7 +83,7 @@ static void test_diag_288(void)
> >    
> >    	snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_288),
> >    			SNIPPET_HDR_START(asm, snippet_pv_diag_288),
> > -			size_gbin, size_hdr, SNIPPET_OFF_ASM);
> > +			size_gbin, size_hdr, SNIPPET_UNPACK_OFF);
> >    
> >    	sie(&vm);
> >    	report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 &&
> > @@ -124,7 +124,7 @@ static void test_diag_yield(void)
> >    
> >    	snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_yield),
> >    			SNIPPET_HDR_START(asm, snippet_pv_diag_yield),
> > -			size_gbin, size_hdr, SNIPPET_OFF_ASM);
> > +			size_gbin, size_hdr, SNIPPET_UNPACK_OFF);
> >    
> >    	/* 0x44 */
> >    	report_prefix_push("0x44");
>
> Steffen Eiden