ARM: kprobes: Add basic API tests

These test that the different kinds of probes can be successfully placed
into ARM and Thumb code and that the handlers are called correctly when
this code is executed.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

arch/arm/kernel/Makefile

@@ -43,6 +43,8 @@ obj-$(CONFIG_KPROBES)		+= kprobes-thumb.o
 else
 obj-$(CONFIG_KPROBES)		+= kprobes-arm.o
 endif
+obj-$(CONFIG_ARM_KPROBES_TEST)	+= test-kprobes.o
+test-kprobes-objs		:= kprobes-test.o
 obj-$(CONFIG_ATAGS_PROC)	+= atags.o
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o

arch/arm/kernel/kprobes-test.c

+/*
+ * arch/arm/kernel/kprobes-test.c
+ *
+ * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+
+#include "kprobes.h"
+
+
+/*
+ * Test basic API
+ */
+
+static bool test_regs_ok;
+static int test_func_instance;
+static int pre_handler_called;
+static int post_handler_called;
+static int jprobe_func_called;
+static int kretprobe_handler_called;
+
+#define FUNC_ARG1 0x12345678
+#define FUNC_ARG2 0xabcdef
+
+
+#ifndef CONFIG_THUMB2_KERNEL
+
+long arm_func(long r0, long r1);
+
+static void __used __naked __arm_kprobes_test_func(void)
+{
+	__asm__ __volatile__ (
+		".arm					\n\t"
+		".type arm_func, %%function		\n\t"
+		"arm_func:				\n\t"
+		"adds	r0, r0, r1			\n\t"
+		"bx	lr				\n\t"
+		".code "NORMAL_ISA	 /* Back to Thumb if necessary */
+		: : : "r0", "r1", "cc"
+	);
+}
+
+#else /* CONFIG_THUMB2_KERNEL */
+
+long thumb16_func(long r0, long r1);
+long thumb32even_func(long r0, long r1);
+long thumb32odd_func(long r0, long r1);
+
+static void __used __naked __thumb_kprobes_test_funcs(void)
+{
+	__asm__ __volatile__ (
+		".type thumb16_func, %%function		\n\t"
+		"thumb16_func:				\n\t"
+		"adds.n	r0, r0, r1			\n\t"
+		"bx	lr				\n\t"
+
+		".align					\n\t"
+		".type thumb32even_func, %%function	\n\t"
+		"thumb32even_func:			\n\t"
+		"adds.w	r0, r0, r1			\n\t"
+		"bx	lr				\n\t"
+
+		".align					\n\t"
+		"nop.n					\n\t"
+		".type thumb32odd_func, %%function	\n\t"
+		"thumb32odd_func:			\n\t"
+		"adds.w	r0, r0, r1			\n\t"
+		"bx	lr				\n\t"
+
+		: : : "r0", "r1", "cc"
+	);
+}
+
+#endif /* CONFIG_THUMB2_KERNEL */
+
+
+static int call_test_func(long (*func)(long, long), bool check_test_regs)
+{
+	long ret;
+
+	++test_func_instance;
+	test_regs_ok = false;
+
+	ret = (*func)(FUNC_ARG1, FUNC_ARG2);
+	if (ret != FUNC_ARG1 + FUNC_ARG2) {
+		pr_err("FAIL: call_test_func: func returned %lx\n", ret);
+		return false;
+	}
+
+	if (check_test_regs && !test_regs_ok) {
+		pr_err("FAIL: test regs not OK\n");
+		return false;
+	}
+
+	return true;
+}
+
+static int __kprobes pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	pre_handler_called = test_func_instance;
+	if (regs->ARM_r0 == FUNC_ARG1 && regs->ARM_r1 == FUNC_ARG2)
+		test_regs_ok = true;
+	return 0;
+}
+
+static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs,
+				unsigned long flags)
+{
+	post_handler_called = test_func_instance;
+	if (regs->ARM_r0 != FUNC_ARG1 + FUNC_ARG2 || regs->ARM_r1 != FUNC_ARG2)
+		test_regs_ok = false;
+}
+
+static struct kprobe the_kprobe = {
+	.addr		= 0,
+	.pre_handler	= pre_handler,
+	.post_handler	= post_handler
+};
+
+static int test_kprobe(long (*func)(long, long))
+{
+	int ret;
+
+	the_kprobe.addr = (kprobe_opcode_t *)func;
+	ret = register_kprobe(&the_kprobe);
+	if (ret < 0) {
+		pr_err("FAIL: register_kprobe failed with %d\n", ret);
+		return ret;
+	}
+
+	ret = call_test_func(func, true);
+
+	unregister_kprobe(&the_kprobe);
+	the_kprobe.flags = 0; /* Clear disable flag to allow reuse */
+
+	if (!ret)
+		return -EINVAL;
+	if (pre_handler_called != test_func_instance) {
+		pr_err("FAIL: kprobe pre_handler not called\n");
+		return -EINVAL;
+	}
+	if (post_handler_called != test_func_instance) {
+		pr_err("FAIL: kprobe post_handler not called\n");
+		return -EINVAL;
+	}
+	if (!call_test_func(func, false))
+		return -EINVAL;
+	if (pre_handler_called == test_func_instance ||
+				post_handler_called == test_func_instance) {
+		pr_err("FAIL: probe called after unregistering\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void __kprobes jprobe_func(long r0, long r1)
+{
+	jprobe_func_called = test_func_instance;
+	if (r0 == FUNC_ARG1 && r1 == FUNC_ARG2)
+		test_regs_ok = true;
+	jprobe_return();
+}
+
+static struct jprobe the_jprobe = {
+	.entry		= jprobe_func,
+};
+
+static int test_jprobe(long (*func)(long, long))
+{
+	int ret;
+
+	the_jprobe.kp.addr = (kprobe_opcode_t *)func;
+	ret = register_jprobe(&the_jprobe);
+	if (ret < 0) {
+		pr_err("FAIL: register_jprobe failed with %d\n", ret);
+		return ret;
+	}
+
+	ret = call_test_func(func, true);
+
+	unregister_jprobe(&the_jprobe);
+	the_jprobe.kp.flags = 0; /* Clear disable flag to allow reuse */
+
+	if (!ret)
+		return -EINVAL;
+	if (jprobe_func_called != test_func_instance) {
+		pr_err("FAIL: jprobe handler function not called\n");
+		return -EINVAL;
+	}
+	if (!call_test_func(func, false))
+		return -EINVAL;
+	if (jprobe_func_called == test_func_instance) {
+		pr_err("FAIL: probe called after unregistering\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int __kprobes
+kretprobe_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	kretprobe_handler_called = test_func_instance;
+	if (regs_return_value(regs) == FUNC_ARG1 + FUNC_ARG2)
+		test_regs_ok = true;
+	return 0;
+}
+
+static struct kretprobe the_kretprobe = {
+	.handler	= kretprobe_handler,
+};
+
+static int test_kretprobe(long (*func)(long, long))
+{
+	int ret;
+
+	the_kretprobe.kp.addr = (kprobe_opcode_t *)func;
+	ret = register_kretprobe(&the_kretprobe);
+	if (ret < 0) {
+		pr_err("FAIL: register_kretprobe failed with %d\n", ret);
+		return ret;
+	}
+
+	ret = call_test_func(func, true);
+
+	unregister_kretprobe(&the_kretprobe);
+	the_kretprobe.kp.flags = 0; /* Clear disable flag to allow reuse */
+
+	if (!ret)
+		return -EINVAL;
+	if (kretprobe_handler_called != test_func_instance) {
+		pr_err("FAIL: kretprobe handler not called\n");
+		return -EINVAL;
+	}
+	if (!call_test_func(func, false))
+		return -EINVAL;
+	if (jprobe_func_called == test_func_instance) {
+		pr_err("FAIL: kretprobe called after unregistering\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int run_api_tests(long (*func)(long, long))
+{
+	int ret;
+
+	pr_info("    kprobe\n");
+	ret = test_kprobe(func);
+	if (ret < 0)
+		return ret;
+
+	pr_info("    jprobe\n");
+	ret = test_jprobe(func);
+	if (ret < 0)
+		return ret;
+
+	pr_info("    kretprobe\n");
+	ret = test_kretprobe(func);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+
+/*
+ * Top level test functions
+ */
+
+static int __init run_all_tests(void)
+{
+	int ret = 0;
+
+	pr_info("Begining kprobe tests...\n");
+
+#ifndef CONFIG_THUMB2_KERNEL
+
+	pr_info("Probe ARM code\n");
+	ret = run_api_tests(arm_func);
+	if (ret)
+		goto out;
+
+#else /* CONFIG_THUMB2_KERNEL */
+
+	pr_info("Probe 16-bit Thumb code\n");
+	ret = run_api_tests(thumb16_func);
+	if (ret)
+		goto out;
+
+	pr_info("Probe 32-bit Thumb code, even halfword\n");
+	ret = run_api_tests(thumb32even_func);
+	if (ret)
+		goto out;
+
+	pr_info("Probe 32-bit Thumb code, odd halfword\n");
+	ret = run_api_tests(thumb32odd_func);
+	if (ret)
+		goto out;
+
+#endif
+
+out:
+	if (ret == 0)
+		pr_info("Finished kprobe tests OK\n");
+	else
+		pr_err("kprobe tests failed\n");
+
+	return ret;
+}
+
+
+/*
+ * Module setup
+ */
+
+#ifdef MODULE
+
+static void __exit kprobe_test_exit(void)
+{
+}
+
+module_init(run_all_tests)
+module_exit(kprobe_test_exit)
+MODULE_LICENSE("GPL");
+
+#else /* !MODULE */
+
+late_initcall(run_all_tests);
+
+#endif