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-rw-r--r--arch/s390/lib/test_unwind.c522
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");