[PATCH] selftests/powerpc: Add test to check is DSCR is corrupted.

[Rashmica Gupta]

If the transaction is aborted, the DSCR should be rolled back to the
checkpointed value before the transaction began.

Signed-off-by: Rashmica Gupta <rashmicy at gmail.com>
---
To check this yourself, undo the changes from the patch "powerpc/tm: Fix
context switching TAR, PPR and DSCR SPRs".

 tools/testing/selftests/powerpc/tm/.gitignore |  1 +
 tools/testing/selftests/powerpc/tm/Makefile   |  2 +-
 tools/testing/selftests/powerpc/tm/tm-dscr.c  | 91 +++++++++++++++++++++++++++
 3 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/powerpc/tm/tm-dscr.c

diff --git a/tools/testing/selftests/powerpc/tm/.gitignore b/tools/testing/selftests/powerpc/tm/.gitignore
index d0c7c97e9b13..76eae258feeb 100644
--- a/tools/testing/selftests/powerpc/tm/.gitignore
+++ b/tools/testing/selftests/powerpc/tm/.gitignore
@@ -3,3 +3,4 @@ tm-syscall
 tm-signal-msr-resv
 tm-signal-stack
 tm-fork
+tm-dscr
diff --git a/tools/testing/selftests/powerpc/tm/Makefile b/tools/testing/selftests/powerpc/tm/Makefile
index f7d4727662aa..59eec240339d 100644
--- a/tools/testing/selftests/powerpc/tm/Makefile
+++ b/tools/testing/selftests/powerpc/tm/Makefile
@@ -1,4 +1,4 @@
-TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack tm-fork
+TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack tm-fork tm-dscr
 
 all: $(TEST_PROGS)
 
diff --git a/tools/testing/selftests/powerpc/tm/tm-dscr.c b/tools/testing/selftests/powerpc/tm/tm-dscr.c
new file mode 100644
index 000000000000..ac44e259c86d
--- /dev/null
+++ b/tools/testing/selftests/powerpc/tm/tm-dscr.c
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2015, Michael Neuling, IBM Corp. 
+ * Licensed under GPLv2.
+ * Original: Michael Neuling 19/7/2013
+ * Edited: Rashmica Gupta 01/12/2015
+ *
+ * Do some transactions, see if the dscr is corrupted. 
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "tm.h"
+#include "utils.h"
+
+#define SPRN_DSCR	0x3
+
+int	num_loops	= 10000;
+
+int test_dscr(void)
+{
+	int i;
+
+	SKIP_IF(!have_htm());
+
+	for (i = 0; i < num_loops; i++)
+	{
+		uint64_t result = 0;
+		asm __volatile__(
+			"li	7, 1;"
+			"mtspr	%[dscr], 7;"	// dscr = 1
+			"tbegin.;"
+			"beq	3f ;"
+			"li	4, 0x7000;"	// Loop lots, to use time
+			"2: ;"		     	// Start loop
+			"li	7, 2;"
+			"mtspr	%[dscr], 7;"	// dscr = 2
+			"tsuspend.;"
+			"li	7, 3;"		
+			"mtspr	%[dscr], 7;"	// dscr = 3
+			"tresume.;"		
+			"subi	4, 4, 1;"
+			"cmpdi	4, 0;"
+			"bne	2b;"
+			"tend.;"
+
+			// Transaction sucess! DSCR should be 3.
+			"mfspr  7, %[dscr];" 
+			"ori	%[res], 7, 4;"	// res = 3|4 = 7
+			"b	4f;"
+			
+			// Abort handler. DSCR should be rolled back to 1.
+			"3:;" 			
+			"mfspr  7, %[dscr];" 	
+			"ori	%[res], 7, 8;"	// res = 1|8 = 9
+			"4:;"
+
+			: [res]"=r"(result)
+			: [dscr]"i"(SPRN_DSCR)
+			: "memory", "r0", "r4", "r7");
+
+		// If result is anything else other than 7 or 9, the dscr
+		// value must have been corrupted.
+		if ((result != 7) && (result != 9))
+			return 1;
+		
+	}
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	
+	// A low number of iterations (eg 100) can cause a false pass.
+	if (argc > 1) {
+		if (strcmp(argv[1], "-h") == 0) {
+			printf("Syntax:\n\t%s [<num loops>]\n",
+			       argv[0]);
+			return 0;
+		} else {
+			num_loops = atoi(argv[1]);
+		}
+	}
+
+	printf("Starting, %d loops\n", num_loops);
+
+	test_harness(test_dscr, "tm_dscr");
+}
-- 
2.5.0