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

Janosch Frank
2022-07-29T08:28:23Z

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 $<
+
+$(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");
--
2.34.1