1 // SPDX-License-Identifier: GPL-2.0-only
3 * Test module for unwind_for_each_frame
6 #define pr_fmt(fmt) "test_unwind: " fmt
7 #include <asm/unwind.h>
8 #include <linux/completion.h>
9 #include <linux/kallsyms.h>
10 #include <linux/kthread.h>
11 #include <linux/module.h>
12 #include <linux/string.h>
13 #include <linux/kprobes.h>
14 #include <linux/wait.h>
16 #include <asm/delay.h>
18 #define BT_BUF_SIZE (PAGE_SIZE * 4)
21 * To avoid printk line limit split backtrace by lines
23 static void print_backtrace(char *bt)
28 p = strsep(&bt, "\n");
36 * Calls unwind_for_each_frame(task, regs, sp) and verifies that the result
37 * contains unwindme_func2 followed by unwindme_func1.
39 static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
42 int frame_count, prev_is_func2, seen_func2_func1;
43 const int max_frames = 128;
44 struct unwind_state state;
49 bt = kmalloc(BT_BUF_SIZE, GFP_ATOMIC);
51 pr_err("failed to allocate backtrace buffer\n");
58 unwind_for_each_frame(&state, task, regs, sp) {
59 unsigned long addr = unwind_get_return_address(&state);
60 char sym[KSYM_SYMBOL_LEN];
62 if (frame_count++ == max_frames)
64 if (state.reliable && !addr) {
65 pr_err("unwind state reliable but addr is 0\n");
68 sprint_symbol(sym, addr);
69 if (bt_pos < BT_BUF_SIZE) {
70 bt_pos += snprintf(bt + bt_pos, BT_BUF_SIZE - bt_pos,
71 state.reliable ? " [%-7s%px] %pSR\n" :
73 stack_type_name(state.stack_info.type),
74 (void *)state.sp, (void *)state.ip);
75 if (bt_pos >= BT_BUF_SIZE)
76 pr_err("backtrace buffer is too small\n");
79 if (prev_is_func2 && str_has_prefix(sym, "unwindme_func1"))
81 prev_is_func2 = str_has_prefix(sym, "unwindme_func2");
84 /* Check the results. */
85 if (unwind_error(&state)) {
86 pr_err("unwind error\n");
89 if (!seen_func2_func1) {
90 pr_err("unwindme_func2 and unwindme_func1 not found\n");
93 if (frame_count == max_frames) {
94 pr_err("Maximum number of frames exceeded\n");
103 /* State of the task being unwound. */
107 struct task_struct *task;
108 struct completion task_ready;
109 wait_queue_head_t task_wq;
113 static struct unwindme *unwindme;
115 /* Values of unwindme.flags. */
116 #define UWM_DEFAULT 0x0
117 #define UWM_THREAD 0x1 /* Unwind a separate task. */
118 #define UWM_REGS 0x2 /* Pass regs to test_unwind(). */
119 #define UWM_SP 0x4 /* Pass sp to test_unwind(). */
120 #define UWM_CALLER 0x8 /* Unwind starting from caller. */
121 #define UWM_SWITCH_STACK 0x10 /* Use CALL_ON_STACK. */
122 #define UWM_IRQ 0x20 /* Unwind from irq context. */
123 #define UWM_PGM 0x40 /* Unwind from program check handler. */
125 static __always_inline unsigned long get_psw_addr(void)
127 unsigned long psw_addr;
130 "basr %[psw_addr],0\n"
131 : [psw_addr] "=d" (psw_addr));
135 #ifdef CONFIG_KPROBES
136 static int pgm_pre_handler(struct kprobe *p, struct pt_regs *regs)
138 struct unwindme *u = unwindme;
140 u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? regs : NULL,
141 (u->flags & UWM_SP) ? u->sp : 0);
146 /* This function may or may not appear in the backtrace. */
147 static noinline int unwindme_func4(struct unwindme *u)
149 if (!(u->flags & UWM_CALLER))
150 u->sp = current_frame_address();
151 if (u->flags & UWM_THREAD) {
152 complete(&u->task_ready);
153 wait_event(u->task_wq, kthread_should_park());
156 #ifdef CONFIG_KPROBES
157 } else if (u->flags & UWM_PGM) {
162 memset(&kp, 0, sizeof(kp));
163 kp.symbol_name = "do_report_trap";
164 kp.pre_handler = pgm_pre_handler;
165 ret = register_kprobe(&kp);
167 pr_err("register_kprobe failed %d\n", ret);
172 * trigger specification exception
180 unregister_kprobe(&kp);
187 memset(®s, 0, sizeof(regs));
188 regs.psw.addr = get_psw_addr();
189 regs.gprs[15] = current_stack_pointer();
190 return test_unwind(NULL,
191 (u->flags & UWM_REGS) ? ®s : NULL,
192 (u->flags & UWM_SP) ? u->sp : 0);
196 /* This function may or may not appear in the backtrace. */
197 static noinline int unwindme_func3(struct unwindme *u)
199 u->sp = current_frame_address();
200 return unwindme_func4(u);
203 /* This function must appear in the backtrace. */
204 static noinline int unwindme_func2(struct unwindme *u)
208 if (u->flags & UWM_SWITCH_STACK) {
210 rc = CALL_ON_STACK(unwindme_func3, S390_lowcore.nodat_stack, 1, u);
214 return unwindme_func3(u);
218 /* This function must follow unwindme_func2 in the backtrace. */
219 static noinline int unwindme_func1(void *u)
221 return unwindme_func2((struct unwindme *)u);
224 static void unwindme_irq_handler(struct ext_code ext_code,
225 unsigned int param32,
226 unsigned long param64)
228 struct unwindme *u = READ_ONCE(unwindme);
230 if (u && u->task == current) {
233 u->ret = unwindme_func1(u);
237 static int test_unwind_irq(struct unwindme *u)
240 if (register_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler)) {
241 pr_info("Couldn't reqister external interrupt handler");
247 unregister_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler);
252 /* Spawns a task and passes it to test_unwind(). */
253 static int test_unwind_task(struct unwindme *u)
255 struct task_struct *task;
258 /* Initialize thread-related fields. */
259 init_completion(&u->task_ready);
260 init_waitqueue_head(&u->task_wq);
263 * Start the task and wait until it reaches unwindme_func4() and sleeps
264 * in (task_ready, unwind_done] range.
266 task = kthread_run(unwindme_func1, u, "%s", __func__);
268 pr_err("kthread_run() failed\n");
269 return PTR_ERR(task);
272 * Make sure task reaches unwindme_func4 before parking it,
273 * we might park it before kthread function has been executed otherwise
275 wait_for_completion(&u->task_ready);
278 ret = test_unwind(task, NULL, (u->flags & UWM_SP) ? u->sp : 0);
283 static int test_unwind_flags(int flags)
288 if (u.flags & UWM_THREAD)
289 return test_unwind_task(&u);
290 else if (u.flags & UWM_IRQ)
291 return test_unwind_irq(&u);
293 return unwindme_func1(&u);
296 static int test_unwind_init(void)
300 #define TEST(flags) \
302 pr_info("[ RUN ] " #flags "\n"); \
303 if (!test_unwind_flags((flags))) { \
304 pr_info("[ OK ] " #flags "\n"); \
306 pr_err("[ FAILED ] " #flags "\n"); \
314 TEST(UWM_SWITCH_STACK);
315 TEST(UWM_SP | UWM_REGS);
316 TEST(UWM_CALLER | UWM_SP);
317 TEST(UWM_CALLER | UWM_SP | UWM_REGS);
318 TEST(UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK);
320 TEST(UWM_THREAD | UWM_SP);
321 TEST(UWM_THREAD | UWM_CALLER | UWM_SP);
323 TEST(UWM_IRQ | UWM_SWITCH_STACK);
324 TEST(UWM_IRQ | UWM_SP);
325 TEST(UWM_IRQ | UWM_REGS);
326 TEST(UWM_IRQ | UWM_SP | UWM_REGS);
327 TEST(UWM_IRQ | UWM_CALLER | UWM_SP);
328 TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS);
329 TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK);
330 #ifdef CONFIG_KPROBES
332 TEST(UWM_PGM | UWM_SP);
333 TEST(UWM_PGM | UWM_REGS);
334 TEST(UWM_PGM | UWM_SP | UWM_REGS);
341 static void test_unwind_exit(void)
345 module_init(test_unwind_init);
346 module_exit(test_unwind_exit);
347 MODULE_LICENSE("GPL");