[PATCH v4 3/4] selftests/powerpc: Add transactional syscall test

[Sam Bobroff]

Check that a syscall made during an active transaction will fail with
the correct failure code and that one made during a suspended
transaction will succeed.

Signed-off-by: Sam Bobroff <sam.bobroff at au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
---
v4:

Incorporated changes suggested by Michael Ellerman:
I added a GPL header, fixed up some formatting, and switched to
__builtin_get_texasru() which works for 32-bit.

v2:

Further testing has shown that the success or failure of the transactions was
affected by minor changes to the code, compiler optimisation and linker
settings.

To address this, I've moved the transactional part of the test to a separate
function, written in assembly. I've also extended the test to as many
transactions as it can fit into ten seconds, to better test for failures that
occur more rarely. This has stabilised the results, and it's no longer
necessary to use special compiler or linker flags.

 tools/testing/selftests/powerpc/tm/.gitignore      |    1 +
 tools/testing/selftests/powerpc/tm/Makefile        |    5 +-
 .../testing/selftests/powerpc/tm/tm-syscall-asm.S  |   27 +++++
 tools/testing/selftests/powerpc/tm/tm-syscall.c    |  121 ++++++++++++++++++++
 4 files changed, 153 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/powerpc/tm/tm-syscall-asm.S
 create mode 100644 tools/testing/selftests/powerpc/tm/tm-syscall.c

diff --git a/tools/testing/selftests/powerpc/tm/.gitignore b/tools/testing/selftests/powerpc/tm/.gitignore
index 33d02cc..2699635d 100644
--- a/tools/testing/selftests/powerpc/tm/.gitignore
+++ b/tools/testing/selftests/powerpc/tm/.gitignore
@@ -1 +1,2 @@
 tm-resched-dscr
+tm-syscall
diff --git a/tools/testing/selftests/powerpc/tm/Makefile b/tools/testing/selftests/powerpc/tm/Makefile
index 2cede23..122cf18 100644
--- a/tools/testing/selftests/powerpc/tm/Makefile
+++ b/tools/testing/selftests/powerpc/tm/Makefile
@@ -1,9 +1,12 @@
-PROGS := tm-resched-dscr
+PROGS := tm-resched-dscr tm-syscall
 
 all: $(PROGS)
 
 $(PROGS): ../harness.c
 
+tm-syscall: tm-syscall-asm.S
+tm-syscall: CFLAGS += -mhtm
+
 run_tests: all
 	@-for PROG in $(PROGS); do \
 		./$$PROG; \
diff --git a/tools/testing/selftests/powerpc/tm/tm-syscall-asm.S b/tools/testing/selftests/powerpc/tm/tm-syscall-asm.S
new file mode 100644
index 0000000..431f61a
--- /dev/null
+++ b/tools/testing/selftests/powerpc/tm/tm-syscall-asm.S
@@ -0,0 +1,27 @@
+#include <ppc-asm.h>
+#include <asm/unistd.h>
+
+	.text
+FUNC_START(getppid_tm_active)
+	tbegin.
+	beq 1f
+	li	r0, __NR_getppid
+	sc
+	tend.
+	blr
+1:
+	li	r3, -1
+	blr
+
+FUNC_START(getppid_tm_suspended)
+	tbegin.
+	beq 1f
+	li	r0, __NR_getppid
+	tsuspend.
+	sc
+	tresume.
+	tend.
+	blr
+1:
+	li	r3, -1
+	blr
diff --git a/tools/testing/selftests/powerpc/tm/tm-syscall.c b/tools/testing/selftests/powerpc/tm/tm-syscall.c
new file mode 100644
index 0000000..3ed8d4b
--- /dev/null
+++ b/tools/testing/selftests/powerpc/tm/tm-syscall.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright 2015, Sam Bobroff, IBM Corp.
+ * Licensed under GPLv2.
+ *
+ * Test the kernel's system call code to ensure that a system call
+ * made from within an active HTM transaction is aborted with the
+ * correct failure code.
+ * Conversely, ensure that a system call made from within a
+ * suspended transaction can succeed.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <asm/tm.h>
+#include <asm/cputable.h>
+#include <linux/auxvec.h>
+#include <sys/time.h>
+#include <stdlib.h>
+
+#include "utils.h"
+
+extern int getppid_tm_active(void);
+extern int getppid_tm_suspended(void);
+
+unsigned retries = 0;
+
+#define TEST_DURATION 10 /* seconds */
+#define TM_RETRIES 100
+
+long failure_code(void)
+{
+	return __builtin_get_texasru() >> 24;
+}
+
+bool failure_is_persistent(void)
+{
+	return (failure_code() & TM_CAUSE_PERSISTENT) == TM_CAUSE_PERSISTENT;
+}
+
+bool failure_is_syscall(void)
+{
+	return (failure_code() & TM_CAUSE_SYSCALL) == TM_CAUSE_SYSCALL;
+}
+
+pid_t getppid_tm(bool suspend)
+{
+	int i;
+	pid_t pid;
+
+	for (i = 0; i < TM_RETRIES; i++) {
+		if (suspend)
+			pid = getppid_tm_suspended();
+		else
+			pid = getppid_tm_active();
+
+		if (pid >= 0)
+			return pid;
+
+		if (failure_is_persistent()) {
+			if (failure_is_syscall())
+				return -1;
+
+			printf("Unexpected persistent transaction failure.\n");
+			printf("TEXASR 0x%016lx, TFIAR 0x%016lx.\n",
+			       __builtin_get_texasr(), __builtin_get_tfiar());
+			exit(-1);
+		}
+
+		retries++;
+	}
+
+	printf("Exceeded limit of %d temporary transaction failures.\n", TM_RETRIES);
+	printf("TEXASR 0x%016lx, TFIAR 0x%016lx.\n",
+	       __builtin_get_texasr(), __builtin_get_tfiar());
+
+	exit(-1);
+}
+
+int tm_syscall(void)
+{
+	unsigned count = 0;
+	struct timeval end, now;
+
+	SKIP_IF(!((long)get_auxv_entry(AT_HWCAP2) & PPC_FEATURE2_HTM));
+	setbuf(stdout, NULL);
+
+	printf("Testing transactional syscalls for %d seconds...\n", TEST_DURATION);
+
+	gettimeofday(&end, NULL);
+	now.tv_sec = TEST_DURATION;
+	now.tv_usec = 0;
+	timeradd(&end, &now, &end);
+
+	for (count = 0; timercmp(&now, &end, <); count++) {
+		/*
+		 * Test a syscall within a suspended transaction and verify
+		 * that it succeeds.
+		 */
+		FAIL_IF(getppid_tm(true) == -1); /* Should succeed. */
+
+		/*
+		 * Test a syscall within an active transaction and verify that
+		 * it fails with the correct failure code.
+		 */
+		FAIL_IF(getppid_tm(false) != -1);  /* Should fail... */
+		FAIL_IF(!failure_is_persistent()); /* ...persistently... */
+		FAIL_IF(!failure_is_syscall());    /* ...with code syscall. */
+		gettimeofday(&now, 0);
+	}
+
+	printf("%d active and suspended transactions behaved correctly.\n", count);
+	printf("(There were %d transaction retries.)\n", retries);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(tm_syscall, "tm_syscall");
+}
-- 
1.7.10.4