s390/test_unwind: extend kretprobe test

Verify unwinding from kretprobed function.

Reviewed-by: Tobias Huschle <huschle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Author: Vasily Gorbik

arch/s390/lib/test_unwind.c

@@ -132,36 +132,50 @@ static struct unwindme *unwindme;
 #define UWM_PGM			0x40	/* Unwind from program check handler */
 #define UWM_KPROBE_ON_FTRACE	0x80	/* Unwind from kprobe handler called via ftrace. */
 #define UWM_FTRACE		0x100	/* Unwind from ftrace handler. */
-#define UWM_KRETPROBE		0x200	/* Unwind kretprobe handlers. */
+#define UWM_KRETPROBE		0x200	/* Unwind through kretprobed function. */
+#define UWM_KRETPROBE_HANDLER	0x400	/* Unwind from kretprobe handler. */
 
-static __always_inline unsigned long get_psw_addr(void)
+static __always_inline struct pt_regs fake_pt_regs(void)
 {
-	unsigned long psw_addr;
+	struct pt_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+	regs.gprs[15] = current_stack_pointer();
 
 	asm volatile(
 		"basr	%[psw_addr],0\n"
-		: [psw_addr] "=d" (psw_addr));
-	return psw_addr;
+		: [psw_addr] "=d" (regs.psw.addr));
+	return regs;
 }
 
 static int kretprobe_ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
 	struct unwindme *u = unwindme;
 
+	if (!(u->flags & UWM_KRETPROBE_HANDLER))
+		return 0;
+
 	u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? regs : NULL,
 			     (u->flags & UWM_SP) ? u->sp : 0);
 
 	return 0;
 }
 
-static noinline notrace void test_unwind_kretprobed_func(void)
+static noinline notrace int test_unwind_kretprobed_func(struct unwindme *u)
 {
-	asm volatile("	nop\n");
+	struct pt_regs regs;
+
+	if (!(u->flags & UWM_KRETPROBE))
+		return 0;
+
+	regs = fake_pt_regs();
+	return test_unwind(NULL, (u->flags & UWM_REGS) ? &regs : NULL,
+			   (u->flags & UWM_SP) ? u->sp : 0);
 }
 
-static noinline void test_unwind_kretprobed_func_caller(void)
+static noinline int test_unwind_kretprobed_func_caller(struct unwindme *u)
 {
-	test_unwind_kretprobed_func();
+	return test_unwind_kretprobed_func(u);
 }
 
 static int test_unwind_kretprobe(struct unwindme *u)
@@ -187,10 +201,12 @@ static int test_unwind_kretprobe(struct unwindme *u)
 		return -EINVAL;
 	}
 
-	test_unwind_kretprobed_func_caller();
+	ret = test_unwind_kretprobed_func_caller(u);
 	unregister_kretprobe(&my_kretprobe);
 	unwindme = NULL;
-	return u->ret;
+	if (u->flags & UWM_KRETPROBE_HANDLER)
+		ret = u->ret;
+	return ret;
 }
 
 static int kprobe_pre_handler(struct kprobe *p, struct pt_regs *regs)
@@ -304,16 +320,13 @@ static noinline int unwindme_func4(struct unwindme *u)
 		return 0;
 	} else if (u->flags & (UWM_PGM | UWM_KPROBE_ON_FTRACE)) {
 		return test_unwind_kprobe(u);
-	} else if (u->flags & (UWM_KRETPROBE)) {
+	} else if (u->flags & (UWM_KRETPROBE | UWM_KRETPROBE_HANDLER)) {
 		return test_unwind_kretprobe(u);
 	} else if (u->flags & UWM_FTRACE) {
 		return test_unwind_ftrace(u);
 	} else {
-		struct pt_regs regs;
+		struct pt_regs regs = fake_pt_regs();
 
-		memset(&regs, 0, sizeof(regs));
-		regs.psw.addr = get_psw_addr();
-		regs.gprs[15] = current_stack_pointer();
 		return test_unwind(NULL,
 				   (u->flags & UWM_REGS) ? &regs : NULL,
 				   (u->flags & UWM_SP) ? u->sp : 0);
@@ -452,6 +465,10 @@ static const struct test_params param_list[] = {
 	TEST_WITH_FLAGS(UWM_KRETPROBE | UWM_SP),
 	TEST_WITH_FLAGS(UWM_KRETPROBE | UWM_REGS),
 	TEST_WITH_FLAGS(UWM_KRETPROBE | UWM_SP | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_KRETPROBE_HANDLER),
+	TEST_WITH_FLAGS(UWM_KRETPROBE_HANDLER | UWM_SP),
+	TEST_WITH_FLAGS(UWM_KRETPROBE_HANDLER | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_KRETPROBE_HANDLER | UWM_SP | UWM_REGS),
 };
 
 /*