Commit 9ba142f4 authored by Vasily Gorbik's avatar Vasily Gorbik
Browse files

s390/test_unwind: fix and extend kprobes test 



Running kprobe test on a kernel built with clang 14 didn't actually
trigger pgm_pre_handler() and no unwinder code was called. Even though
do_report_trap() is a global symbol, clang inlined it in several local
functions including illegal_op() handler, so that kprobbing a global
symbol didn't have a desired effect.

To achieve the same test result (unwinding from a program check
handler) introduce a local function and probe an instruction in the
middle, so that kprobe doesn't take KPROBE_ON_FTRACE path.

While at it, add another test for KPROBE_ON_FTRACE.

Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 829ec749

arch/s390/lib/test_unwind.c

+50 −33
Original line number Diff line number Diff line
@@ -129,8 +129,9 @@ static struct unwindme *unwindme; 
#define UWM_CALLER		0x8	/* Unwind starting from caller. */

#define UWM_SWITCH_STACK	0x10	/* Use call_on_stack. */

#define UWM_IRQ			0x20	/* Unwind from irq context. */

#define UWM_PGM			0x40	/* Unwind from program check handler. */

#define UWM_FTRACE		0x80	/* Unwind from ftrace handler. */

#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. */



static __always_inline unsigned long get_psw_addr(void)

{
@@ -142,7 +143,7 @@ static __always_inline unsigned long get_psw_addr(void) 
	return psw_addr;

}



static int pgm_pre_handler(struct kprobe *p, struct pt_regs *regs)

static int kprobe_pre_handler(struct kprobe *p, struct pt_regs *regs)

{

	struct unwindme *u = unwindme;
@@ -151,6 +152,46 @@ static int pgm_pre_handler(struct kprobe *p, struct pt_regs *regs) 
	return 0;

}



extern const char test_unwind_kprobed_insn[];



static noinline void test_unwind_kprobed_func(void)

{

	asm volatile(

		"	nopr	%%r7\n"

		"test_unwind_kprobed_insn:\n"

		"	nopr	%%r7\n"

		:);

}



static int test_unwind_kprobe(struct unwindme *u)

{

	struct kprobe kp;

	int ret;



	if (!IS_ENABLED(CONFIG_KPROBES))

		kunit_skip(current_test, "requires CONFIG_KPROBES");

	if (!IS_ENABLED(CONFIG_KPROBES_ON_FTRACE) && u->flags & UWM_KPROBE_ON_FTRACE)

		kunit_skip(current_test, "requires CONFIG_KPROBES_ON_FTRACE");



	u->ret = -1; /* make sure kprobe is called */

	unwindme = u;

	memset(&kp, 0, sizeof(kp));

	kp.pre_handler = kprobe_pre_handler;

	kp.addr = u->flags & UWM_KPROBE_ON_FTRACE ?

				(kprobe_opcode_t *)test_unwind_kprobed_func :

				(kprobe_opcode_t *)test_unwind_kprobed_insn;

	ret = register_kprobe(&kp);

	if (ret < 0) {

		kunit_err(current_test, "register_kprobe failed %d\n", ret);

		return -EINVAL;

	}



	test_unwind_kprobed_func();

	unregister_kprobe(&kp);

	unwindme = NULL;

	return u->ret;

}



static void notrace __used test_unwind_ftrace_handler(unsigned long ip,

						      unsigned long parent_ip,

						      struct ftrace_ops *fops,
@@ -212,36 +253,8 @@ static noinline int unwindme_func4(struct unwindme *u) 
		wait_event(u->task_wq, kthread_should_park());

		kthread_parkme();

		return 0;

	} else if (u->flags & UWM_PGM) {

		struct kprobe kp;

		int ret;



		if (!IS_ENABLED(CONFIG_KPROBES))

			kunit_skip(current_test, "requires CONFIG_KPROBES");



		unwindme = u;

		memset(&kp, 0, sizeof(kp));

		kp.symbol_name = "do_report_trap";

		kp.pre_handler = pgm_pre_handler;

		ret = register_kprobe(&kp);

		if (ret < 0) {

			kunit_err(current_test, "register_kprobe failed %d\n", ret);

			return -EINVAL;

		}



		/*

		 * Trigger operation exception; use insn notation to bypass

		 * llvm's integrated assembler sanity checks.

		 */

		asm volatile(

			"	.insn	e,0x0000\n"	/* illegal opcode */

			"0:	nopr	%%r7\n"

			EX_TABLE(0b, 0b)

			:);



		unregister_kprobe(&kp);

		unwindme = NULL;

		return u->ret;

	} else if (u->flags & (UWM_PGM | UWM_KPROBE_ON_FTRACE)) {

		return test_unwind_kprobe(u);

	} else if (u->flags & UWM_FTRACE) {

		return test_unwind_ftrace(u);

	} else {
@@ -376,6 +389,10 @@ static const struct test_params param_list[] = { 
	TEST_WITH_FLAGS(UWM_PGM | UWM_SP),

	TEST_WITH_FLAGS(UWM_PGM | UWM_REGS),

	TEST_WITH_FLAGS(UWM_PGM | UWM_SP | UWM_REGS),

	TEST_WITH_FLAGS(UWM_KPROBE_ON_FTRACE),

	TEST_WITH_FLAGS(UWM_KPROBE_ON_FTRACE | UWM_SP),

	TEST_WITH_FLAGS(UWM_KPROBE_ON_FTRACE | UWM_REGS),

	TEST_WITH_FLAGS(UWM_KPROBE_ON_FTRACE | UWM_SP | UWM_REGS),

	TEST_WITH_FLAGS(UWM_FTRACE),

	TEST_WITH_FLAGS(UWM_FTRACE | UWM_SP),

	TEST_WITH_FLAGS(UWM_FTRACE | UWM_REGS),