arch/s390/lib/test_unwind.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Test module for unwind_for_each_frame
  */

 #define pr_fmt(fmt) "test_unwind: " fmt
 #include <asm/unwind.h>
 #include <linux/completion.h>
 #include <linux/kallsyms.h>
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/kprobes.h>
 #include <linux/wait.h>
 #include <asm/irq.h>
 #include <asm/delay.h>

 #define BT_BUF_SIZE (PAGE_SIZE * 4)

 /*
  * 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;
 		pr_err("%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;
 	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) {
 		pr_err("failed to allocate backtrace buffer\n");
 		return -ENOMEM;
 	}
 	/* Unwind. */
 	frame_count = 0;
 	prev_is_func2 = 0;
 	seen_func2_func1 = 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) {
 			pr_err("unwind state reliable but addr is 0\n");
 			kfree(bt);
 			return -EINVAL;
 		}
 		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)
 				pr_err("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");
 	}

 	/* Check the results. */
 	if (unwind_error(&state)) {
 		pr_err("unwind error\n");
 		ret = -EINVAL;
 	}
 	if (!seen_func2_func1) {
 		pr_err("unwindme_func2 and unwindme_func1 not found\n");
 		ret = -EINVAL;
 	}
 	if (frame_count == max_frames) {
 		pr_err("Maximum number of frames exceeded\n");
 		ret = -EINVAL;
 	}
 	if (ret)
 		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. */

 static __always_inline unsigned long get_psw_addr(void)
 {
 	unsigned long psw_addr;

 	asm volatile(
 		"basr	%[psw_addr],0\n"
 		: [psw_addr] "=d" (psw_addr));
 	return psw_addr;
 }

 #ifdef CONFIG_KPROBES
 static int pgm_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;
 }
 #endif

 /* 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;
 #ifdef CONFIG_KPROBES
 	} else if (u->flags & UWM_PGM) {
 		struct kprobe kp;
 		int ret;

 		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) {
 			pr_err("register_kprobe failed %d\n", ret);
 			return -EINVAL;
 		}

 		/*
 		 * trigger specification exception
 		 */
 		asm volatile(
 			"	mvcl	%%r1,%%r1\n"
 			"0:	nopr	%%r7\n"
 			EX_TABLE(0b, 0b)
 			:);

 		unregister_kprobe(&kp);
 		unwindme = NULL;
 		return u->ret;
 #endif
 	} else {
 		struct pt_regs 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);
 	}
 }

 /* 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)
 {
 	int rc;

 	if (u->flags & UWM_SWITCH_STACK) {
 		preempt_disable();
 		rc = CALL_ON_STACK(unwindme_func3, S390_lowcore.nodat_stack, 1, u);
 		preempt_enable();
 		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_irq_handler(struct ext_code ext_code,
 				       unsigned int param32,
 				       unsigned long param64)
 {
 	struct unwindme *u = READ_ONCE(unwindme);

 	if (u && u->task == current) {
 		unwindme = NULL;
 		u->task = NULL;
 		u->ret = unwindme_func1(u);
 	}
 }

 static int test_unwind_irq(struct unwindme *u)
 {
 	preempt_disable();
 	if (register_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler)) {
 		pr_info("Couldn't register external interrupt handler");
 		return -1;
 	}
 	u->task = current;
 	unwindme = u;
 	udelay(1);
 	unregister_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler);
 	preempt_enable();
 	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)) {
 		pr_err("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;
 }

 static int test_unwind_flags(int flags)
 {
 	struct unwindme u;

 	u.flags = flags;
 	if (u.flags & UWM_THREAD)
 		return test_unwind_task(&u);
 	else if (u.flags & UWM_IRQ)
 		return test_unwind_irq(&u);
 	else
 		return unwindme_func1(&u);
 }

 static int test_unwind_init(void)
 {
 	int ret = 0;

 #define TEST(flags)							\
 do {									\
 	pr_info("[ RUN      ] " #flags "\n");				\
 	if (!test_unwind_flags((flags))) {				\
 		pr_info("[       OK ] " #flags "\n");			\
 	} else {							\
 		pr_err("[  FAILED  ] " #flags "\n");			\
 		ret = -EINVAL;						\
 	}								\
 } while (0)

 	TEST(UWM_DEFAULT);
 	TEST(UWM_SP);
 	TEST(UWM_REGS);
 	TEST(UWM_SWITCH_STACK);
 	TEST(UWM_SP | UWM_REGS);
 	TEST(UWM_CALLER | UWM_SP);
 	TEST(UWM_CALLER | UWM_SP | UWM_REGS);
 	TEST(UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK);
 	TEST(UWM_THREAD);
 	TEST(UWM_THREAD | UWM_SP);
 	TEST(UWM_THREAD | UWM_CALLER | UWM_SP);
 	TEST(UWM_IRQ);
 	TEST(UWM_IRQ | UWM_SWITCH_STACK);
 	TEST(UWM_IRQ | UWM_SP);
 	TEST(UWM_IRQ | UWM_REGS);
 	TEST(UWM_IRQ | UWM_SP | UWM_REGS);
 	TEST(UWM_IRQ | UWM_CALLER | UWM_SP);
 	TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS);
 	TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK);
 #ifdef CONFIG_KPROBES
 	TEST(UWM_PGM);
 	TEST(UWM_PGM | UWM_SP);
 	TEST(UWM_PGM | UWM_REGS);
 	TEST(UWM_PGM | UWM_SP | UWM_REGS);
 #endif
 #undef TEST

 	return ret;
 }

 static void test_unwind_exit(void)
 {
 }

 module_init(test_unwind_init);
 module_exit(test_unwind_exit);
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Test module for unwind_for_each_frame
	*/

	#define pr_fmt(fmt) "test_unwind: " fmt
	#include <asm/unwind.h>
	#include <linux/completion.h>
	#include <linux/kallsyms.h>
	#include <linux/kthread.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/string.h>
	#include <linux/kprobes.h>
	#include <linux/wait.h>
	#include <asm/irq.h>
	#include <asm/delay.h>

	#define BT_BUF_SIZE (PAGE_SIZE * 4)

	/*
	* 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;
	pr_err("%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;
	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) {
	pr_err("failed to allocate backtrace buffer\n");
	return -ENOMEM;
	}
	/* Unwind. */
	frame_count = 0;
	prev_is_func2 = 0;
	seen_func2_func1 = 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) {
	pr_err("unwind state reliable but addr is 0\n");
	kfree(bt);
	return -EINVAL;
	}
	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)
	pr_err("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");
	}

	/* Check the results. */
	if (unwind_error(&state)) {
	pr_err("unwind error\n");
	ret = -EINVAL;
	}
	if (!seen_func2_func1) {
	pr_err("unwindme_func2 and unwindme_func1 not found\n");
	ret = -EINVAL;
	}
	if (frame_count == max_frames) {
	pr_err("Maximum number of frames exceeded\n");
	ret = -EINVAL;
	}
	if (ret)
	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. */

	static __always_inline unsigned long get_psw_addr(void)
	{
	unsigned long psw_addr;

	asm volatile(
	"basr %[psw_addr],0\n"
	: [psw_addr] "=d" (psw_addr));
	return psw_addr;
	}

	#ifdef CONFIG_KPROBES
	static int pgm_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;
	}
	#endif

	/* 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;
	#ifdef CONFIG_KPROBES
	} else if (u->flags & UWM_PGM) {
	struct kprobe kp;
	int ret;

	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) {
	pr_err("register_kprobe failed %d\n", ret);
	return -EINVAL;
	}

	/*
	* trigger specification exception
	*/
	asm volatile(
	" mvcl %%r1,%%r1\n"
	"0: nopr %%r7\n"
	EX_TABLE(0b, 0b)
	:);

	unregister_kprobe(&kp);
	unwindme = NULL;
	return u->ret;
	#endif
	} else {
	struct pt_regs 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);
	}
	}

	/* 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)
	{
	int rc;

	if (u->flags & UWM_SWITCH_STACK) {
	preempt_disable();
	rc = CALL_ON_STACK(unwindme_func3, S390_lowcore.nodat_stack, 1, u);
	preempt_enable();
	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_irq_handler(struct ext_code ext_code,
	unsigned int param32,
	unsigned long param64)
	{
	struct unwindme *u = READ_ONCE(unwindme);

	if (u && u->task == current) {
	unwindme = NULL;
	u->task = NULL;
	u->ret = unwindme_func1(u);
	}
	}

	static int test_unwind_irq(struct unwindme *u)
	{
	preempt_disable();
	if (register_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler)) {
	pr_info("Couldn't register external interrupt handler");
	return -1;
	}
	u->task = current;
	unwindme = u;
	udelay(1);
	unregister_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler);
	preempt_enable();
	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)) {
	pr_err("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;
	}

	static int test_unwind_flags(int flags)
	{
	struct unwindme u;

	u.flags = flags;
	if (u.flags & UWM_THREAD)
	return test_unwind_task(&u);
	else if (u.flags & UWM_IRQ)
	return test_unwind_irq(&u);
	else
	return unwindme_func1(&u);
	}

	static int test_unwind_init(void)
	{
	int ret = 0;

	#define TEST(flags) \
	do { \
	pr_info("[ RUN ] " #flags "\n"); \
	if (!test_unwind_flags((flags))) { \
	pr_info("[ OK ] " #flags "\n"); \
	} else { \
	pr_err("[ FAILED ] " #flags "\n"); \
	ret = -EINVAL; \
	} \
	} while (0)

	TEST(UWM_DEFAULT);
	TEST(UWM_SP);
	TEST(UWM_REGS);
	TEST(UWM_SWITCH_STACK);
	TEST(UWM_SP \| UWM_REGS);
	TEST(UWM_CALLER \| UWM_SP);
	TEST(UWM_CALLER \| UWM_SP \| UWM_REGS);
	TEST(UWM_CALLER \| UWM_SP \| UWM_REGS \| UWM_SWITCH_STACK);
	TEST(UWM_THREAD);
	TEST(UWM_THREAD \| UWM_SP);
	TEST(UWM_THREAD \| UWM_CALLER \| UWM_SP);
	TEST(UWM_IRQ);
	TEST(UWM_IRQ \| UWM_SWITCH_STACK);
	TEST(UWM_IRQ \| UWM_SP);
	TEST(UWM_IRQ \| UWM_REGS);
	TEST(UWM_IRQ \| UWM_SP \| UWM_REGS);
	TEST(UWM_IRQ \| UWM_CALLER \| UWM_SP);
	TEST(UWM_IRQ \| UWM_CALLER \| UWM_SP \| UWM_REGS);
	TEST(UWM_IRQ \| UWM_CALLER \| UWM_SP \| UWM_REGS \| UWM_SWITCH_STACK);
	#ifdef CONFIG_KPROBES
	TEST(UWM_PGM);
	TEST(UWM_PGM \| UWM_SP);
	TEST(UWM_PGM \| UWM_REGS);
	TEST(UWM_PGM \| UWM_SP \| UWM_REGS);
	#endif
	#undef TEST

	return ret;
	}

	static void test_unwind_exit(void)
	{
	}

	module_init(test_unwind_init);
	module_exit(test_unwind_exit);
	MODULE_LICENSE("GPL");