[Qemu-devel] [PATCH v2 2/2] s390/bios: Make the s390-ccw.img relocatable

[Thomas Huth <thuth@linux.vnet.ibm.com>]

The current bios sits at location 0x7e00000 in the guest RAM
and thus prevents loading of bigger ramdisks. By making the
image relocatable we can move it to the end of the RAM so that
it is getting out of the way.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
---
 hw/s390x/ipl.c            |   23 +++++++++++++++++++++--
 pc-bios/s390-ccw/Makefile |   11 ++++++-----
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index b57adbd..ab7fd8a 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -14,6 +14,7 @@
 #include "sysemu/sysemu.h"
 #include "cpu.h"
 #include "elf.h"
+#include "exec/ram_addr.h"
 #include "hw/loader.h"
 #include "hw/sysbus.h"
 #include "hw/s390x/virtio-ccw.h"
@@ -95,6 +96,16 @@ static const VMStateDescription vmstate_ipl = {
      }
 };
 
+static uint64_t bios_translate_addr(void *opaque, uint64_t srcaddr)
+{
+    uint64_t dstaddr = (uint64_t)opaque;
+    /*
+     * Assuming that our s390-ccw.img was linked for starting at address 0,
+     * we can simply add the destination address for the final location
+     */
+    return srcaddr + dstaddr;
+}
+
 static int s390_ipl_init(SysBusDevice *dev)
 {
     S390IPLState *ipl = S390_IPL(dev);
@@ -109,6 +120,8 @@ static int s390_ipl_init(SysBusDevice *dev)
      * even if an external kernel has been defined.
      */
     if (!ipl->kernel || ipl->enforce_bios) {
+        uint64_t fwbase = (MIN(ram_size, 0x80000000U) - 0x200000) & ~0xffffUL;
+
         if (bios_name == NULL) {
             bios_name = ipl->firmware;
         }
@@ -118,9 +131,15 @@ static int s390_ipl_init(SysBusDevice *dev)
             hw_error("could not find stage1 bootloader\n");
         }
 
-        bios_size = load_elf(bios_filename, NULL, NULL, &ipl->bios_start_addr,
+        bios_size = load_elf(bios_filename, bios_translate_addr,
+                             (void *)fwbase, &ipl->bios_start_addr,
                              NULL, NULL, 1, ELF_MACHINE, 0);
-        if (bios_size < 0) {
+
+        if (bios_size > 0) {
+            /* Adjust ELF start address to final location */
+            ipl->bios_start_addr += fwbase;
+        } else {
+            /* Try to load non-ELF file (e.g. s390-zipl.rom) */
             bios_size = load_image_targphys(bios_filename, ZIPL_IMAGE_START,
                                             4096);
             ipl->bios_start_addr = ZIPL_IMAGE_START;
diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index ad55a14..009bb8d 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -9,10 +9,9 @@ $(call set-vpath, $(SRC_PATH)/pc-bios/s390-ccw)
 
 .PHONY : all clean build-all
 
-OBJECTS=main.o bootmap.o sclp-ascii.o virtio.o start.o
-CFLAGS += -fno-stack-protector
-# XXX find a more clever to locate the bootloader
-LDFLAGS += -Wl,-Ttext,0x7e00000,-Tbss,0x7f00000 -nostdlib
+OBJECTS = start.o main.o bootmap.o sclp-ascii.o virtio.o
+CFLAGS += -fPIE -fno-stack-protector -ffreestanding
+LDFLAGS += -Wl,-pie -nostdlib
 
 build-all: s390-ccw.img
 
@@ -20,7 +19,9 @@ s390-ccw.elf: $(OBJECTS)
 	$(call quiet-command,$(CC) $(LDFLAGS) -o $@ $(OBJECTS),"  Building $(TARGET_DIR)$@")
 
 s390-ccw.img: s390-ccw.elf
-	$(call quiet-command,strip $< -o $@,"  Stripping $(TARGET_DIR)$@")
+	$(call quiet-command,strip --strip-unneeded $< -o $@,"  Stripping $(TARGET_DIR)$@")
+
+$(OBJECTS): Makefile
 
 clean:
 	rm -f *.o *.d *.img *.elf *~
-- 
1.7.1