1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Test module for unwind_for_each_frame 4 */ 5 6 #include <kunit/test.h> 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/timer.h> 13 #include <linux/slab.h> 14 #include <linux/string.h> 15 #include <linux/kprobes.h> 16 #include <linux/wait.h> 17 #include <asm/irq.h> 18 19 struct kunit *current_test; 20 21 #define BT_BUF_SIZE (PAGE_SIZE * 4) 22 23 /* 24 * To avoid printk line limit split backtrace by lines 25 */ 26 static void print_backtrace(char *bt) 27 { 28 char *p; 29 30 while (true) { 31 p = strsep(&bt, "\n"); 32 if (!p) 33 break; 34 kunit_err(current_test, "%s\n", p); 35 } 36 } 37 38 /* 39 * Calls unwind_for_each_frame(task, regs, sp) and verifies that the result 40 * contains unwindme_func2 followed by unwindme_func1. 41 */ 42 static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs, 43 unsigned long sp) 44 { 45 int frame_count, prev_is_func2, seen_func2_func1; 46 const int max_frames = 128; 47 struct unwind_state state; 48 size_t bt_pos = 0; 49 int ret = 0; 50 char *bt; 51 52 bt = kmalloc(BT_BUF_SIZE, GFP_ATOMIC); 53 if (!bt) { 54 kunit_err(current_test, "failed to allocate backtrace buffer\n"); 55 return -ENOMEM; 56 } 57 /* Unwind. */ 58 frame_count = 0; 59 prev_is_func2 = 0; 60 seen_func2_func1 = 0; 61 unwind_for_each_frame(&state, task, regs, sp) { 62 unsigned long addr = unwind_get_return_address(&state); 63 char sym[KSYM_SYMBOL_LEN]; 64 65 if (frame_count++ == max_frames) 66 break; 67 if (state.reliable && !addr) { 68 kunit_err(current_test, "unwind state reliable but addr is 0\n"); 69 ret = -EINVAL; 70 break; 71 } 72 sprint_symbol(sym, addr); 73 if (bt_pos < BT_BUF_SIZE) { 74 bt_pos += snprintf(bt + bt_pos, BT_BUF_SIZE - bt_pos, 75 state.reliable ? " [%-7s%px] %pSR\n" : 76 "([%-7s%px] %pSR)\n", 77 stack_type_name(state.stack_info.type), 78 (void *)state.sp, (void *)state.ip); 79 if (bt_pos >= BT_BUF_SIZE) 80 kunit_err(current_test, "backtrace buffer is too small\n"); 81 } 82 frame_count += 1; 83 if (prev_is_func2 && str_has_prefix(sym, "unwindme_func1")) 84 seen_func2_func1 = 1; 85 prev_is_func2 = str_has_prefix(sym, "unwindme_func2"); 86 } 87 88 /* Check the results. */ 89 if (unwind_error(&state)) { 90 kunit_err(current_test, "unwind error\n"); 91 ret = -EINVAL; 92 } 93 if (!seen_func2_func1) { 94 kunit_err(current_test, "unwindme_func2 and unwindme_func1 not found\n"); 95 ret = -EINVAL; 96 } 97 if (frame_count == max_frames) { 98 kunit_err(current_test, "Maximum number of frames exceeded\n"); 99 ret = -EINVAL; 100 } 101 if (ret) 102 print_backtrace(bt); 103 kfree(bt); 104 return ret; 105 } 106 107 /* State of the task being unwound. */ 108 struct unwindme { 109 int flags; 110 int ret; 111 struct task_struct *task; 112 struct completion task_ready; 113 wait_queue_head_t task_wq; 114 unsigned long sp; 115 }; 116 117 static struct unwindme *unwindme; 118 119 /* Values of unwindme.flags. */ 120 #define UWM_DEFAULT 0x0 121 #define UWM_THREAD 0x1 /* Unwind a separate task. */ 122 #define UWM_REGS 0x2 /* Pass regs to test_unwind(). */ 123 #define UWM_SP 0x4 /* Pass sp to test_unwind(). */ 124 #define UWM_CALLER 0x8 /* Unwind starting from caller. */ 125 #define UWM_SWITCH_STACK 0x10 /* Use call_on_stack. */ 126 #define UWM_IRQ 0x20 /* Unwind from irq context. */ 127 #define UWM_PGM 0x40 /* Unwind from program check handler. */ 128 129 static __always_inline unsigned long get_psw_addr(void) 130 { 131 unsigned long psw_addr; 132 133 asm volatile( 134 "basr %[psw_addr],0\n" 135 : [psw_addr] "=d" (psw_addr)); 136 return psw_addr; 137 } 138 139 static int pgm_pre_handler(struct kprobe *p, struct pt_regs *regs) 140 { 141 struct unwindme *u = unwindme; 142 143 u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? regs : NULL, 144 (u->flags & UWM_SP) ? u->sp : 0); 145 return 0; 146 } 147 148 /* This function may or may not appear in the backtrace. */ 149 static noinline int unwindme_func4(struct unwindme *u) 150 { 151 if (!(u->flags & UWM_CALLER)) 152 u->sp = current_frame_address(); 153 if (u->flags & UWM_THREAD) { 154 complete(&u->task_ready); 155 wait_event(u->task_wq, kthread_should_park()); 156 kthread_parkme(); 157 return 0; 158 } else if (u->flags & UWM_PGM) { 159 struct kprobe kp; 160 int ret; 161 162 if (!IS_ENABLED(CONFIG_KPROBES)) 163 kunit_skip(current_test, "requires CONFIG_KPROBES"); 164 165 unwindme = u; 166 memset(&kp, 0, sizeof(kp)); 167 kp.symbol_name = "do_report_trap"; 168 kp.pre_handler = pgm_pre_handler; 169 ret = register_kprobe(&kp); 170 if (ret < 0) { 171 kunit_err(current_test, "register_kprobe failed %d\n", ret); 172 return -EINVAL; 173 } 174 175 /* 176 * Trigger operation exception; use insn notation to bypass 177 * llvm's integrated assembler sanity checks. 178 */ 179 asm volatile( 180 " .insn e,0x0000\n" /* illegal opcode */ 181 "0: nopr %%r7\n" 182 EX_TABLE(0b, 0b) 183 :); 184 185 unregister_kprobe(&kp); 186 unwindme = NULL; 187 return u->ret; 188 } else { 189 struct pt_regs regs; 190 191 memset(®s, 0, sizeof(regs)); 192 regs.psw.addr = get_psw_addr(); 193 regs.gprs[15] = current_stack_pointer(); 194 return test_unwind(NULL, 195 (u->flags & UWM_REGS) ? ®s : NULL, 196 (u->flags & UWM_SP) ? u->sp : 0); 197 } 198 } 199 200 /* This function may or may not appear in the backtrace. */ 201 static noinline int unwindme_func3(struct unwindme *u) 202 { 203 u->sp = current_frame_address(); 204 return unwindme_func4(u); 205 } 206 207 /* This function must appear in the backtrace. */ 208 static noinline int unwindme_func2(struct unwindme *u) 209 { 210 unsigned long flags; 211 int rc; 212 213 if (u->flags & UWM_SWITCH_STACK) { 214 local_irq_save(flags); 215 local_mcck_disable(); 216 rc = call_on_stack(1, S390_lowcore.nodat_stack, 217 int, unwindme_func3, struct unwindme *, u); 218 local_mcck_enable(); 219 local_irq_restore(flags); 220 return rc; 221 } else { 222 return unwindme_func3(u); 223 } 224 } 225 226 /* This function must follow unwindme_func2 in the backtrace. */ 227 static noinline int unwindme_func1(void *u) 228 { 229 return unwindme_func2((struct unwindme *)u); 230 } 231 232 static void unwindme_timer_fn(struct timer_list *unused) 233 { 234 struct unwindme *u = READ_ONCE(unwindme); 235 236 if (u) { 237 unwindme = NULL; 238 u->task = NULL; 239 u->ret = unwindme_func1(u); 240 complete(&u->task_ready); 241 } 242 } 243 244 static struct timer_list unwind_timer; 245 246 static int test_unwind_irq(struct unwindme *u) 247 { 248 unwindme = u; 249 init_completion(&u->task_ready); 250 timer_setup(&unwind_timer, unwindme_timer_fn, 0); 251 mod_timer(&unwind_timer, jiffies + 1); 252 wait_for_completion(&u->task_ready); 253 return u->ret; 254 } 255 256 /* Spawns a task and passes it to test_unwind(). */ 257 static int test_unwind_task(struct kunit *test, struct unwindme *u) 258 { 259 struct task_struct *task; 260 int ret; 261 262 /* Initialize thread-related fields. */ 263 init_completion(&u->task_ready); 264 init_waitqueue_head(&u->task_wq); 265 266 /* 267 * Start the task and wait until it reaches unwindme_func4() and sleeps 268 * in (task_ready, unwind_done] range. 269 */ 270 task = kthread_run(unwindme_func1, u, "%s", __func__); 271 if (IS_ERR(task)) { 272 kunit_err(test, "kthread_run() failed\n"); 273 return PTR_ERR(task); 274 } 275 /* 276 * Make sure task reaches unwindme_func4 before parking it, 277 * we might park it before kthread function has been executed otherwise 278 */ 279 wait_for_completion(&u->task_ready); 280 kthread_park(task); 281 /* Unwind. */ 282 ret = test_unwind(task, NULL, (u->flags & UWM_SP) ? u->sp : 0); 283 kthread_stop(task); 284 return ret; 285 } 286 287 struct test_params { 288 int flags; 289 char *name; 290 }; 291 292 /* 293 * Create required parameter list for tests 294 */ 295 static const struct test_params param_list[] = { 296 {.flags = UWM_DEFAULT, .name = "UWM_DEFAULT"}, 297 {.flags = UWM_SP, .name = "UWM_SP"}, 298 {.flags = UWM_REGS, .name = "UWM_REGS"}, 299 {.flags = UWM_SWITCH_STACK, 300 .name = "UWM_SWITCH_STACK"}, 301 {.flags = UWM_SP | UWM_REGS, 302 .name = "UWM_SP | UWM_REGS"}, 303 {.flags = UWM_CALLER | UWM_SP, 304 .name = "WM_CALLER | UWM_SP"}, 305 {.flags = UWM_CALLER | UWM_SP | UWM_REGS, 306 .name = "UWM_CALLER | UWM_SP | UWM_REGS"}, 307 {.flags = UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK, 308 .name = "UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK"}, 309 {.flags = UWM_THREAD, .name = "UWM_THREAD"}, 310 {.flags = UWM_THREAD | UWM_SP, 311 .name = "UWM_THREAD | UWM_SP"}, 312 {.flags = UWM_THREAD | UWM_CALLER | UWM_SP, 313 .name = "UWM_THREAD | UWM_CALLER | UWM_SP"}, 314 {.flags = UWM_IRQ, .name = "UWM_IRQ"}, 315 {.flags = UWM_IRQ | UWM_SWITCH_STACK, 316 .name = "UWM_IRQ | UWM_SWITCH_STACK"}, 317 {.flags = UWM_IRQ | UWM_SP, 318 .name = "UWM_IRQ | UWM_SP"}, 319 {.flags = UWM_IRQ | UWM_REGS, 320 .name = "UWM_IRQ | UWM_REGS"}, 321 {.flags = UWM_IRQ | UWM_SP | UWM_REGS, 322 .name = "UWM_IRQ | UWM_SP | UWM_REGS"}, 323 {.flags = UWM_IRQ | UWM_CALLER | UWM_SP, 324 .name = "UWM_IRQ | UWM_CALLER | UWM_SP"}, 325 {.flags = UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS, 326 .name = "UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS"}, 327 {.flags = UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK, 328 .name = "UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK"}, 329 {.flags = UWM_PGM, .name = "UWM_PGM"}, 330 {.flags = UWM_PGM | UWM_SP, 331 .name = "UWM_PGM | UWM_SP"}, 332 {.flags = UWM_PGM | UWM_REGS, 333 .name = "UWM_PGM | UWM_REGS"}, 334 {.flags = UWM_PGM | UWM_SP | UWM_REGS, 335 .name = "UWM_PGM | UWM_SP | UWM_REGS"}, 336 }; 337 338 /* 339 * Parameter description generator: required for KUNIT_ARRAY_PARAM() 340 */ 341 static void get_desc(const struct test_params *params, char *desc) 342 { 343 strscpy(desc, params->name, KUNIT_PARAM_DESC_SIZE); 344 } 345 346 /* 347 * Create test_unwind_gen_params 348 */ 349 KUNIT_ARRAY_PARAM(test_unwind, param_list, get_desc); 350 351 static void test_unwind_flags(struct kunit *test) 352 { 353 struct unwindme u; 354 const struct test_params *params; 355 356 current_test = test; 357 params = (const struct test_params *)test->param_value; 358 u.flags = params->flags; 359 if (u.flags & UWM_THREAD) 360 KUNIT_EXPECT_EQ(test, 0, test_unwind_task(test, &u)); 361 else if (u.flags & UWM_IRQ) 362 KUNIT_EXPECT_EQ(test, 0, test_unwind_irq(&u)); 363 else 364 KUNIT_EXPECT_EQ(test, 0, unwindme_func1(&u)); 365 } 366 367 static struct kunit_case unwind_test_cases[] = { 368 KUNIT_CASE_PARAM(test_unwind_flags, test_unwind_gen_params), 369 {} 370 }; 371 372 static struct kunit_suite test_unwind_suite = { 373 .name = "test_unwind", 374 .test_cases = unwind_test_cases, 375 }; 376 377 kunit_test_suites(&test_unwind_suite); 378 379 MODULE_LICENSE("GPL"); 380