3 files changed, 25 insertions, 6 deletions
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 40dd47970a3..e518dd53eff 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -27,7 +27,6 @@
 #define DEFSYS_CMD_SIZE		96
 #define SAVESYS_CMD_SIZE	32
 
-extern int _eshared;
 char kernel_nss_name[NSS_NAME_SIZE + 1];
 
 #ifdef CONFIG_SHARED_KERNEL
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index b2e1dc89a8c..a466bab6677 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -155,15 +155,34 @@ void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
 static int __kprobes swap_instruction(void *aref)
 {
 	struct ins_replace_args *args = aref;
+	u32 *addr;
+	u32 instr;
 	int err = -EFAULT;
 
+	/*
+	 * Text segment is read-only, hence we use stura to bypass dynamic
+	 * address translation to exchange the instruction. Since stura
+	 * always operates on four bytes, but we only want to exchange two
+	 * bytes do some calculations to get things right. In addition we
+	 * shall not cross any page boundaries (vmalloc area!) when writing
+	 * the new instruction.
+	 */
+	addr = (u32 *)ALIGN((unsigned long)args->ptr, 4);
+	if ((unsigned long)args->ptr & 2)
+		instr = ((*addr) & 0xffff0000) | args->new;
+	else
+		instr = ((*addr) & 0x0000ffff) | args->new << 16;
+
 	asm volatile(
-		"0: mvc  0(2,%2),0(%3)\n"
-		"1: la   %0,0\n"
+		"	lra	%1,0(%1)\n"
+		"0:	stura	%2,%1\n"
+		"1:	la	%0,0\n"
 		"2:\n"
 		EX_TABLE(0b,2b)
-		: "+d" (err), "=m" (*args->ptr)
-		: "a" (args->ptr), "a" (&args->new), "m" (args->new));
+		: "+d" (err)
+		: "a" (addr), "d" (instr)
+		: "memory", "cc");
+
 	return err;
 }
 
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 8fedb1f9fc9..a4890739252 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -35,9 +35,10 @@ SECTIONS
 
 #ifdef CONFIG_SHARED_KERNEL
   . = ALIGN(1048576);		/* VM shared segments are 1MB aligned */
+#endif
 
+  . = ALIGN(4096);
   _eshared = .;			/* End of shareable data */
-#endif
 
   . = ALIGN(16);		/* Exception table */
   __start___ex_table = .;