From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Date: Tue, 8 Apr 2014 15:52:01 +0000 (+0200)
Subject: fio: fix s390 nop
X-Git-Tag: fio-2.1.8~7^2
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=1cffeb6f92dab701dfae0a6f5e52375deba422b7;hp=919e789d0999bf13ef1ae670c536d2aef3709894

fio: fix s390 nop

When trying to run rate limited fio runs we encountered that the current
definition of a nop uses a privileged instruction which is not even a nop,
but a yield call to the hipervisor.
That leads to a SIGILL as it is privileged.

To solve that issue replace it with a nop, the assembler will take care
of it (likely to become a BCR 0,0)

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/arch/arch-s390.h b/arch/arch-s390.h
index 2c205de3..56cb2302 100644
--- a/arch/arch-s390.h
+++ b/arch/arch-s390.h
@@ -18,7 +18,7 @@
 #define __NR_sys_vmsplice	309
 #endif
 
-#define nop		asm volatile ("diag 0,0,68" : : : "memory")
+#define nop		asm volatile("nop" : : : "memory")
 #define read_barrier()	asm volatile("bcr 15,0" : : : "memory")
 #define write_barrier()	asm volatile("bcr 15,0" : : : "memory")