3 files changed, 10 insertions, 1 deletions
diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
index fbae45b03c..b9c70d64a5 100644
--- a/pc-bios/s390-ccw/jump2ipl.c
+++ b/pc-bios/s390-ccw/jump2ipl.c
@@ -78,7 +78,7 @@ void jump_to_low_kernel(void)
      * kernel start address (when jumping to the PSW-at-zero address instead,
      * the kernel startup code fails when we booted from a network device).
      */
-    if (!memcmp((char *)0x10008, "S390EP", 6)) {
+    if (!memcmp((char *)S390EP, "S390EP", 6)) {
         jump_to_IPL_code(KERN_IMAGE_START);
     }
 
diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index fc4bfaa455..5d2b7ba94d 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -178,6 +178,12 @@ static void boot_setup(void)
     memcpy(lpmsg + 10, loadparm_str, 8);
     sclp_print(lpmsg);
 
+    /*
+     * Clear out any potential S390EP magic (see jump_to_low_kernel()),
+     * so we don't taint our decision-making process during a reboot.
+     */
+    memset((char *)S390EP, 0, 6);
+
     have_iplb = store_iplb(&iplb);
 }
 
diff --git a/pc-bios/s390-ccw/s390-arch.h b/pc-bios/s390-ccw/s390-arch.h
index 6da44d4436..a741488aaa 100644
--- a/pc-bios/s390-ccw/s390-arch.h
+++ b/pc-bios/s390-ccw/s390-arch.h
@@ -95,6 +95,9 @@ typedef struct LowCore {
 
 extern LowCore *lowcore;
 
+/* Location of "S390EP" in a Linux binary (see arch/s390/boot/head.S) */
+#define S390EP 0x10008
+
 static inline void set_prefix(uint32_t address)
 {
     asm volatile("spx %0" : : "m" (address) : "memory");