[kvm-unit-tests PATCH v8 4/6] s390x: lib: add SPX and STPX instruction wrapper

[Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>]

Add a wrapper for the SET PREFIX and STORE PREFIX instructions, and
use it instead of using inline assembly.

Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
 lib/s390x/asm/arch_def.h | 13 +++++++++++++
 s390x/intercept.c        | 24 +++++++++---------------
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 1a5e3c6..15a4d49 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -284,4 +284,17 @@ static inline int servc(uint32_t command, unsigned long sccb)
 	return cc;
 }
 
+static inline void set_prefix(uint32_t new_prefix)
+{
+	asm volatile("	spx %0" : : "Q" (new_prefix) : "memory");
+}
+
+static inline uint32_t get_prefix(void)
+{
+	uint32_t current_prefix;
+
+	asm volatile("	stpx %0" : "=Q" (current_prefix));
+	return current_prefix;
+}
+
 #endif
diff --git a/s390x/intercept.c b/s390x/intercept.c
index 3696e33..5f46b82 100644
--- a/s390x/intercept.c
+++ b/s390x/intercept.c
@@ -13,6 +13,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/interrupt.h>
 #include <asm/page.h>
+#include <asm/facility.h>
 
 static uint8_t pagebuf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
 
@@ -26,13 +27,10 @@ static void test_stpx(void)
 	uint32_t new_prefix = (uint32_t)(intptr_t)pagebuf;
 
 	/* Can we successfully change the prefix? */
-	asm volatile (
-		" stpx	%0\n"
-		" spx	%2\n"
-		" stpx	%1\n"
-		" spx	%0\n"
-		: "+Q"(old_prefix), "+Q"(tst_prefix)
-		: "Q"(new_prefix));
+	old_prefix = get_prefix();
+	set_prefix(new_prefix);
+	tst_prefix = get_prefix();
+	set_prefix(old_prefix);
 	report(old_prefix == 0 && tst_prefix == new_prefix, "store prefix");
 
 	expect_pgm_int();
@@ -63,14 +61,10 @@ static void test_spx(void)
 	 * some facility bits there ... at least some of them should be
 	 * set in our buffer afterwards.
 	 */
-	asm volatile (
-		" stpx	%0\n"
-		" spx	%1\n"
-		" stfl	0\n"
-		" spx	%0\n"
-		: "+Q"(old_prefix)
-		: "Q"(new_prefix)
-		: "memory");
+	old_prefix = get_prefix();
+	set_prefix(new_prefix);
+	stfl();
+	set_prefix(old_prefix);
 	report(pagebuf[GEN_LC_STFL] != 0, "stfl to new prefix");
 
 	expect_pgm_int();
-- 
2.24.1