[v3] selftests/powerpc: Add test to check if TAR is corrupted

[Rashmica Gupta]

If the transaction is aborted, the TAR should be rolled back to the
checkpointed value before the transaction began. The value written to the
TAR when the transaction is suspended should only remain there if the
transaction completes successfully.

Signed-off-by: Rashmica Gupta <rashmicy at gmail.com>
---
Added more explanation and fixed up styling issue. No functional
changes.

 tools/testing/selftests/powerpc/tm/.gitignore |  1 +
 tools/testing/selftests/powerpc/tm/Makefile   |  2 +-
 tools/testing/selftests/powerpc/tm/tm-tar.c   | 92 +++++++++++++++++++++++++++
 3 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/powerpc/tm/tm-tar.c

diff --git a/tools/testing/selftests/powerpc/tm/.gitignore b/tools/testing/selftests/powerpc/tm/.gitignore
index 76eae258feeb..9bf6749550e3 100644
--- a/tools/testing/selftests/powerpc/tm/.gitignore
+++ b/tools/testing/selftests/powerpc/tm/.gitignore
@@ -4,3 +4,4 @@ tm-signal-msr-resv
 tm-signal-stack
 tm-fork
 tm-dscr
+tm-tar
diff --git a/tools/testing/selftests/powerpc/tm/Makefile b/tools/testing/selftests/powerpc/tm/Makefile
index 59eec240339d..ab2992f69b4c 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 tm-dscr
+TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack tm-fork tm-dscr tm-tar
 
 all: $(TEST_PROGS)
 
diff --git a/tools/testing/selftests/powerpc/tm/tm-tar.c b/tools/testing/selftests/powerpc/tm/tm-tar.c
new file mode 100644
index 000000000000..732f518c95cf
--- /dev/null
+++ b/tools/testing/selftests/powerpc/tm/tm-tar.c
@@ -0,0 +1,92 @@
+/*
+ * 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 tar is corrupted.
+ * If the transaction is aborted, the TAR should be rolled back to the
+ * checkpointed value before the transaction began. The value written to
+ * TAR in suspended mode should only remain in TAR if the transaction
+ * completes.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "tm.h"
+#include "utils.h"
+
+#define SPRN_TAR	0x32f
+
+int	num_loops	= 10000;
+
+int test_tar(void)
+{
+	int i;
+
+	SKIP_IF(!have_htm());
+
+	for (i = 0; i < num_loops; i++)
+	{
+		uint64_t result = 0;
+		asm __volatile__(
+			"li	7, 1;"
+			"mtspr	%[tar], 7;"	/* tar = 1 */
+			"tbegin.;"
+			"beq	3f;"
+			"li	4, 0x7000;"	/* Loop lots, to use time */
+			"2:;"			/* Start loop */
+			"li	7, 2;"
+			"mtspr	%[tar], 7;"	/* tar = 2 */
+			"tsuspend.;"
+			"li	7, 3;"
+			"mtspr	%[tar], 7;"	/* tar = 3 */
+			"tresume.;"
+			"subi	4, 4, 1;"
+			"cmpdi	4, 0;"
+			"bne	2b;"
+			"tend.;"
+
+			/* Transaction sucess! TAR should be 3 */
+			"mfspr  7, %[tar];"
+			"ori	%[res], 7, 4;"  // res = 3|4 = 7
+			"b	4f;"
+
+			/* Abort handler. TAR should be rolled back to 1 */
+			"3:;"
+			"mfspr  7, %[tar];"
+			"ori	%[res], 7, 8;"	// res = 1|8 = 9
+			"4:;"
+
+			: [res]"=r"(result)
+			: [tar]"i"(SPRN_TAR)
+			   : "memory", "r0", "r4", "r7");
+
+		/* If result is anything else other than 7 or 9, the tar
+		 * 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_tar, "tm_tar");
+}
-- 
2.5.0