// 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_arch_rethook_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_arch_rethook_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, "arch_rethook_trampoline+0x0/"))
seen_arch_rethook_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_arch_rethook_trampoline) {
kunit_err(current_test, "arch_rethook_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(®s, 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) ? ®s : 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) ? ®s : 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, mflags;
int rc;
if (u->flags & UWM_SWITCH_STACK) {
local_irq_save(flags);
local_mcck_save(mflags);
rc = call_on_stack(1, get_lowcore()->nodat_stack,
int, unwindme_func3, struct unwindme *, u);
local_mcck_restore(mflags);
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_DESCRIPTION("KUnit test for unwind_for_each_frame");
MODULE_LICENSE("GPL");
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