1 files changed, 522 insertions, 0 deletions

diff --git a/arch/s390/lib/test_unwind.c b/arch/s390/lib/test_unwind.c
new file mode 100644
index 000000000..5a053b393
--- /dev/null
+++ b/arch/s390/lib/test_unwind.c
@@ -0,0 +1,522 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test module for unwind_for_each_frame
+ */
+
+#include <kunit/test.h>
+#include <asm/unwind.h>
+#include <linux/completion.h>
+#include <linux/kallsyms.h>
+#include <linux/kthread.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/kprobes.h>
+#include <linux/wait.h>
+#include <asm/irq.h>
+
+static struct kunit *current_test;
+
+#define BT_BUF_SIZE (PAGE_SIZE * 4)
+
+static bool force_bt;
+module_param_named(backtrace, force_bt, bool, 0444);
+MODULE_PARM_DESC(backtrace, "print backtraces for all tests");
+
+/*
+ * To avoid printk line limit split backtrace by lines
+ */
+static void print_backtrace(char *bt)
+{
+	char *p;
+
+	while (true) {
+		p = strsep(&bt, "\n");
+		if (!p)
+			break;
+		kunit_err(current_test, "%s\n", p);
+	}
+}
+
+/*
+ * Calls unwind_for_each_frame(task, regs, sp) and verifies that the result
+ * contains unwindme_func2 followed by unwindme_func1.
+ */
+static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
+				unsigned long sp)
+{
+	int frame_count, prev_is_func2, seen_func2_func1, seen_kretprobe_trampoline;
+	const int max_frames = 128;
+	struct unwind_state state;
+	size_t bt_pos = 0;
+	int ret = 0;
+	char *bt;
+
+	bt = kmalloc(BT_BUF_SIZE, GFP_ATOMIC);
+	if (!bt) {
+		kunit_err(current_test, "failed to allocate backtrace buffer\n");
+		return -ENOMEM;
+	}
+	/* Unwind. */
+	frame_count = 0;
+	prev_is_func2 = 0;
+	seen_func2_func1 = 0;
+	seen_kretprobe_trampoline = 0;
+	unwind_for_each_frame(&state, task, regs, sp) {
+		unsigned long addr = unwind_get_return_address(&state);
+		char sym[KSYM_SYMBOL_LEN];
+
+		if (frame_count++ == max_frames)
+			break;
+		if (state.reliable && !addr) {
+			kunit_err(current_test, "unwind state reliable but addr is 0\n");
+			ret = -EINVAL;
+			break;
+		}
+		sprint_symbol(sym, addr);
+		if (bt_pos < BT_BUF_SIZE) {
+			bt_pos += snprintf(bt + bt_pos, BT_BUF_SIZE - bt_pos,
+					   state.reliable ? " [%-7s%px] %pSR\n" :
+							    "([%-7s%px] %pSR)\n",
+					   stack_type_name(state.stack_info.type),
+					   (void *)state.sp, (void *)state.ip);
+			if (bt_pos >= BT_BUF_SIZE)
+				kunit_err(current_test, "backtrace buffer is too small\n");
+		}
+		frame_count += 1;
+		if (prev_is_func2 && str_has_prefix(sym, "unwindme_func1"))
+			seen_func2_func1 = 1;
+		prev_is_func2 = str_has_prefix(sym, "unwindme_func2");
+		if (str_has_prefix(sym, "__kretprobe_trampoline+0x0/"))
+			seen_kretprobe_trampoline = 1;
+	}
+
+	/* Check the results. */
+	if (unwind_error(&state)) {
+		kunit_err(current_test, "unwind error\n");
+		ret = -EINVAL;
+	}
+	if (!seen_func2_func1) {
+		kunit_err(current_test, "unwindme_func2 and unwindme_func1 not found\n");
+		ret = -EINVAL;
+	}
+	if (frame_count == max_frames) {
+		kunit_err(current_test, "Maximum number of frames exceeded\n");
+		ret = -EINVAL;
+	}
+	if (seen_kretprobe_trampoline) {
+		kunit_err(current_test, "__kretprobe_trampoline+0x0 in unwinding results\n");
+		ret = -EINVAL;
+	}
+	if (ret || force_bt)
+		print_backtrace(bt);
+	kfree(bt);
+	return ret;
+}
+
+/* State of the task being unwound. */
+struct unwindme {
+	int flags;
+	int ret;
+	struct task_struct *task;
+	struct completion task_ready;
+	wait_queue_head_t task_wq;
+	unsigned long sp;
+};
+
+static struct unwindme *unwindme;
+
+/* Values of unwindme.flags. */
+#define UWM_DEFAULT		0x0
+#define UWM_THREAD		0x1	/* Unwind a separate task. */
+#define UWM_REGS		0x2	/* Pass regs to test_unwind(). */
+#define UWM_SP			0x4	/* Pass sp to test_unwind(). */
+#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_KPROBE_ON_FTRACE	0x80	/* Unwind from kprobe handler called via ftrace. */
+#define UWM_FTRACE		0x100	/* Unwind from ftrace handler. */
+#define UWM_KRETPROBE		0x200	/* Unwind through kretprobed function. */
+#define UWM_KRETPROBE_HANDLER	0x400	/* Unwind from kretprobe handler. */
+
+static __always_inline struct pt_regs fake_pt_regs(void)
+{
+	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" (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 int test_unwind_kretprobed_func(struct unwindme *u)
+{
+	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 int test_unwind_kretprobed_func_caller(struct unwindme *u)
+{
+	return test_unwind_kretprobed_func(u);
+}
+
+static int test_unwind_kretprobe(struct unwindme *u)
+{
+	int ret;
+	struct kretprobe my_kretprobe;
+
+	if (!IS_ENABLED(CONFIG_KPROBES))
+		kunit_skip(current_test, "requires CONFIG_KPROBES");
+
+	u->ret = -1; /* make sure kprobe is called */
+	unwindme = u;
+
+	memset(&my_kretprobe, 0, sizeof(my_kretprobe));
+	my_kretprobe.handler = kretprobe_ret_handler;
+	my_kretprobe.maxactive = 1;
+	my_kretprobe.kp.addr = (kprobe_opcode_t *)test_unwind_kretprobed_func;
+
+	ret = register_kretprobe(&my_kretprobe);
+
+	if (ret < 0) {
+		kunit_err(current_test, "register_kretprobe failed %d\n", ret);
+		return -EINVAL;
+	}
+
+	ret = test_unwind_kretprobed_func_caller(u);
+	unregister_kretprobe(&my_kretprobe);
+	unwindme = NULL;
+	if (u->flags & UWM_KRETPROBE_HANDLER)
+		ret = u->ret;
+	return ret;
+}
+
+static int kprobe_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct unwindme *u = unwindme;
+
+	u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? regs : NULL,
+			     (u->flags & UWM_SP) ? u->sp : 0);
+	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,
+						      struct ftrace_regs *fregs)
+{
+	struct unwindme *u = (struct unwindme *)fregs->regs.gprs[2];
+
+	u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? &fregs->regs : NULL,
+			     (u->flags & UWM_SP) ? u->sp : 0);
+}
+
+static noinline int test_unwind_ftraced_func(struct unwindme *u)
+{
+	return READ_ONCE(u)->ret;
+}
+
+static int test_unwind_ftrace(struct unwindme *u)
+{
+	int ret;
+#ifdef CONFIG_DYNAMIC_FTRACE
+	struct ftrace_ops *fops;
+
+	fops = kunit_kzalloc(current_test, sizeof(*fops), GFP_KERNEL);
+	fops->func = test_unwind_ftrace_handler;
+	fops->flags = FTRACE_OPS_FL_DYNAMIC |
+		     FTRACE_OPS_FL_RECURSION |
+		     FTRACE_OPS_FL_SAVE_REGS |
+		     FTRACE_OPS_FL_PERMANENT;
+#else
+	kunit_skip(current_test, "requires CONFIG_DYNAMIC_FTRACE");
+#endif
+
+	ret = ftrace_set_filter_ip(fops, (unsigned long)test_unwind_ftraced_func, 0, 0);
+	if (ret) {
+		kunit_err(current_test, "failed to set ftrace filter (%d)\n", ret);
+		return -1;
+	}
+
+	ret = register_ftrace_function(fops);
+	if (!ret) {
+		ret = test_unwind_ftraced_func(u);
+		unregister_ftrace_function(fops);
+	} else {
+		kunit_err(current_test, "failed to register ftrace handler (%d)\n", ret);
+	}
+
+	ftrace_set_filter_ip(fops, (unsigned long)test_unwind_ftraced_func, 1, 0);
+	return ret;
+}
+
+/* This function may or may not appear in the backtrace. */
+static noinline int unwindme_func4(struct unwindme *u)
+{
+	if (!(u->flags & UWM_CALLER))
+		u->sp = current_frame_address();
+	if (u->flags & UWM_THREAD) {
+		complete(&u->task_ready);
+		wait_event(u->task_wq, kthread_should_park());
+		kthread_parkme();
+		return 0;
+	} else if (u->flags & (UWM_PGM | UWM_KPROBE_ON_FTRACE)) {
+		return test_unwind_kprobe(u);
+	} 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 = fake_pt_regs();
+
+		return test_unwind(NULL,
+				   (u->flags & UWM_REGS) ? &regs : NULL,
+				   (u->flags & UWM_SP) ? u->sp : 0);
+	}
+}
+
+/* This function may or may not appear in the backtrace. */
+static noinline int unwindme_func3(struct unwindme *u)
+{
+	u->sp = current_frame_address();
+	return unwindme_func4(u);
+}
+
+/* This function must appear in the backtrace. */
+static noinline int unwindme_func2(struct unwindme *u)
+{
+	unsigned long flags;
+	int rc;
+
+	if (u->flags & UWM_SWITCH_STACK) {
+		local_irq_save(flags);
+		local_mcck_disable();
+		rc = call_on_stack(1, S390_lowcore.nodat_stack,
+				   int, unwindme_func3, struct unwindme *, u);
+		local_mcck_enable();
+		local_irq_restore(flags);
+		return rc;
+	} else {
+		return unwindme_func3(u);
+	}
+}
+
+/* This function must follow unwindme_func2 in the backtrace. */
+static noinline int unwindme_func1(void *u)
+{
+	return unwindme_func2((struct unwindme *)u);
+}
+
+static void unwindme_timer_fn(struct timer_list *unused)
+{
+	struct unwindme *u = READ_ONCE(unwindme);
+
+	if (u) {
+		unwindme = NULL;
+		u->task = NULL;
+		u->ret = unwindme_func1(u);
+		complete(&u->task_ready);
+	}
+}
+
+static struct timer_list unwind_timer;
+
+static int test_unwind_irq(struct unwindme *u)
+{
+	unwindme = u;
+	init_completion(&u->task_ready);
+	timer_setup(&unwind_timer, unwindme_timer_fn, 0);
+	mod_timer(&unwind_timer, jiffies + 1);
+	wait_for_completion(&u->task_ready);
+	return u->ret;
+}
+
+/* Spawns a task and passes it to test_unwind(). */
+static int test_unwind_task(struct unwindme *u)
+{
+	struct task_struct *task;
+	int ret;
+
+	/* Initialize thread-related fields. */
+	init_completion(&u->task_ready);
+	init_waitqueue_head(&u->task_wq);
+
+	/*
+	 * Start the task and wait until it reaches unwindme_func4() and sleeps
+	 * in (task_ready, unwind_done] range.
+	 */
+	task = kthread_run(unwindme_func1, u, "%s", __func__);
+	if (IS_ERR(task)) {
+		kunit_err(current_test, "kthread_run() failed\n");
+		return PTR_ERR(task);
+	}
+	/*
+	 * Make sure task reaches unwindme_func4 before parking it,
+	 * we might park it before kthread function has been executed otherwise
+	 */
+	wait_for_completion(&u->task_ready);
+	kthread_park(task);
+	/* Unwind. */
+	ret = test_unwind(task, NULL, (u->flags & UWM_SP) ? u->sp : 0);
+	kthread_stop(task);
+	return ret;
+}
+
+struct test_params {
+	int flags;
+	char *name;
+};
+
+/*
+ * Create required parameter list for tests
+ */
+#define TEST_WITH_FLAGS(f) { .flags = f, .name = #f }
+static const struct test_params param_list[] = {
+	TEST_WITH_FLAGS(UWM_DEFAULT),
+	TEST_WITH_FLAGS(UWM_SP),
+	TEST_WITH_FLAGS(UWM_REGS),
+	TEST_WITH_FLAGS(UWM_SWITCH_STACK),
+	TEST_WITH_FLAGS(UWM_SP | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_CALLER | UWM_SP),
+	TEST_WITH_FLAGS(UWM_CALLER | UWM_SP | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK),
+	TEST_WITH_FLAGS(UWM_THREAD),
+	TEST_WITH_FLAGS(UWM_THREAD | UWM_SP),
+	TEST_WITH_FLAGS(UWM_THREAD | UWM_CALLER | UWM_SP),
+	TEST_WITH_FLAGS(UWM_IRQ),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_SWITCH_STACK),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_SP),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_SP | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_CALLER | UWM_SP),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK),
+	TEST_WITH_FLAGS(UWM_PGM),
+	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),
+	TEST_WITH_FLAGS(UWM_FTRACE | UWM_SP | UWM_REGS),
+	TEST_WITH_FLAGS(UWM_KRETPROBE),
+	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),
+};
+
+/*
+ * Parameter description generator: required for KUNIT_ARRAY_PARAM()
+ */
+static void get_desc(const struct test_params *params, char *desc)
+{
+	strscpy(desc, params->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+/*
+ * Create test_unwind_gen_params
+ */
+KUNIT_ARRAY_PARAM(test_unwind, param_list, get_desc);
+
+static void test_unwind_flags(struct kunit *test)
+{
+	struct unwindme u;
+	const struct test_params *params;
+
+	current_test = test;
+	params = (const struct test_params *)test->param_value;
+	u.flags = params->flags;
+	if (u.flags & UWM_THREAD)
+		KUNIT_EXPECT_EQ(test, 0, test_unwind_task(&u));
+	else if (u.flags & UWM_IRQ)
+		KUNIT_EXPECT_EQ(test, 0, test_unwind_irq(&u));
+	else
+		KUNIT_EXPECT_EQ(test, 0, unwindme_func1(&u));
+}
+
+static struct kunit_case unwind_test_cases[] = {
+	KUNIT_CASE_PARAM(test_unwind_flags, test_unwind_gen_params),
+	{}
+};
+
+static struct kunit_suite test_unwind_suite = {
+	.name = "test_unwind",
+	.test_cases = unwind_test_cases,
+};
+
+kunit_test_suites(&test_unwind_suite);
+
+MODULE_LICENSE("GPL");