selftests/powerpc: Add transactional syscall test

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@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/tm/.gitignore

 tm-resched-dscr
+tm-syscall

tools/testing/selftests/powerpc/tm/Makefile

-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; \

tools/testing/selftests/powerpc/tm/tm-syscall-asm.S

+#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

tools/testing/selftests/powerpc/tm/tm-syscall.c

+/*
+ * 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");
+}