[PATCH 2/3] s390x: snippets: Add snippet compilation

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

From: Steffen Eiden <seiden@linux.ibm.com>

This patch provides the necessary make targets to properly compile
snippets and link them into their associated host.

To define the guest-host definition, we use the make-feature
`SECONDEXPANSION` in combination with `Target specific Variable
Values`. The variable `snippets` has different values depending on the
current target. This enables us to define which snippets (=guests)
belong to which hosts. Furthermore, using the second-expansion, we can
use `snippets` in the perquisites of the host's `%.elf` rule, which
otherwise would be not set.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 s390x/Makefile | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/s390x/Makefile b/s390x/Makefile
index 8820e99..ba32f4c 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -76,11 +76,26 @@ OBJDIRS += lib/s390x
 asmlib = $(TEST_DIR)/cstart64.o $(TEST_DIR)/cpu.o
 
 FLATLIBS = $(libcflat)
-%.elf: %.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)
+
+SNIPPET_DIR = $(TEST_DIR)/snippets
+snippet_asmlib = $(SNIPPET_DIR)/c/cstart.o
+
+# perquisites (=guests) for the snippet hosts.
+# $(TEST_DIR)/<snippet-host>.elf: snippets = $(SNIPPET_DIR)/<c/asm>/<snippet>.gbin
+
+$(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.o $(FLATLIBS)
+	$(OBJCOPY) -O binary $(patsubst %.gbin,%.o,$@) $@
+	$(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $@ $@
+
+$(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_asmlib) $(FLATLIBS)
+	$(CC) $(LDFLAGS) -o $@ -T $(SNIPPET_DIR)/c/flat.lds $(patsubst %.gbin,%.o,$@) $(snippet_asmlib) $(FLATLIBS)
+	$(OBJCOPY) -O binary $@ $@
+	$(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $@ $@
+
+.SECONDEXPANSION:
+%.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) $(snippets) $(@:.elf=.aux.o)
 	$(RM) $(@:.elf=.aux.o)
 	@chmod a-x $@
 
@@ -94,7 +109,7 @@ 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} $(TEST_DIR)/.*.d $(SNIPPET_DIR)/c/*.{o,gbin} $(SNIPPET_DIR)/c/.*.d lib/s390x/.*.d
 
 generated-files = $(asm-offsets)
 $(tests:.elf=.o) $(asmlib) $(cflatobjs): $(generated-files)
-- 
2.27.0