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

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

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)
+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)
 	$(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) $(@:.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);
+}
-- 
2.30.2