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

Janosch Frank
2022-07-29T14:42:22Z

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@linux.ibm.com>
>> ---
>> 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