s390/dis: use explicit buf len

Pass buffer length in extra parameter.

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/processor.h

@@ -161,7 +161,8 @@ extern unsigned long thread_saved_pc(struct task_struct *t);
 
 extern void show_code(struct pt_regs *regs);
 extern void print_fn_code(unsigned char *code, unsigned long len);
-extern int insn_to_mnemonic(unsigned char *instruction, char buf[8]);
+extern int insn_to_mnemonic(unsigned char *instruction, char *buf,
+			    unsigned int len);
 
 unsigned long get_wchan(struct task_struct *p);
 #define task_pt_regs(tsk) ((struct pt_regs *) \

arch/s390/kernel/dis.c

@@ -1696,14 +1696,15 @@ static struct insn *find_insn(unsigned char *code)
  * insn_to_mnemonic - decode an s390 instruction
  * @instruction: instruction to decode
  * @buf: buffer to fill with mnemonic
+ * @len: length of buffer
  *
  * Decode the instruction at @instruction and store the corresponding
- * mnemonic into @buf.
+ * mnemonic into @buf of length @len.
  * @buf is left unchanged if the instruction could not be decoded.
  * Returns:
  *  %0 on success, %-ENOENT if the instruction was not found.
  */
-int insn_to_mnemonic(unsigned char *instruction, char buf[8])
+int insn_to_mnemonic(unsigned char *instruction, char *buf, unsigned int len)
 {
 	struct insn *insn;
 
@@ -1711,10 +1712,10 @@ int insn_to_mnemonic(unsigned char *instruction, char buf[8])
 	if (!insn)
 		return -ENOENT;
 	if (insn->name[0] == '\0')
-		snprintf(buf, 8, "%s",
+		snprintf(buf, len, "%s",
 			 long_insn_name[(int) insn->name[1]]);
 	else
-		snprintf(buf, 8, "%.5s", insn->name);
+		snprintf(buf, len, "%.5s", insn->name);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(insn_to_mnemonic);

arch/s390/kvm/trace.h

@@ -117,7 +117,7 @@ TRACE_EVENT(kvm_s390_intercept_instruction,
 			   __entry->instruction,
 			   insn_to_mnemonic((unsigned char *)
 					    &__entry->instruction,
-					 __entry->insn) ?
+					 __entry->insn, sizeof(__entry->insn)) ?
 			   "unknown" : __entry->insn)
 	);