1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others. 7 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org) 8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc. 9 * Copyright (C) 2004 Thiemo Seufer 10 */ 11 #include <linux/errno.h> 12 #include <linux/module.h> 13 #include <linux/sched.h> 14 #include <linux/tick.h> 15 #include <linux/kernel.h> 16 #include <linux/mm.h> 17 #include <linux/stddef.h> 18 #include <linux/unistd.h> 19 #include <linux/ptrace.h> 20 #include <linux/mman.h> 21 #include <linux/personality.h> 22 #include <linux/sys.h> 23 #include <linux/user.h> 24 #include <linux/init.h> 25 #include <linux/completion.h> 26 #include <linux/kallsyms.h> 27 #include <linux/random.h> 28 29 #include <asm/asm.h> 30 #include <asm/bootinfo.h> 31 #include <asm/cpu.h> 32 #include <asm/dsp.h> 33 #include <asm/fpu.h> 34 #include <asm/pgtable.h> 35 #include <asm/system.h> 36 #include <asm/mipsregs.h> 37 #include <asm/processor.h> 38 #include <asm/uaccess.h> 39 #include <asm/io.h> 40 #include <asm/elf.h> 41 #include <asm/isadep.h> 42 #include <asm/inst.h> 43 #include <asm/stacktrace.h> 44 45 /* 46 * The idle thread. There's no useful work to be done, so just try to conserve 47 * power and have a low exit latency (ie sit in a loop waiting for somebody to 48 * say that they'd like to reschedule) 49 */ 50 void __noreturn cpu_idle(void) 51 { 52 int cpu; 53 54 /* CPU is going idle. */ 55 cpu = smp_processor_id(); 56 57 /* endless idle loop with no priority at all */ 58 while (1) { 59 tick_nohz_stop_sched_tick(1); 60 while (!need_resched() && cpu_online(cpu)) { 61 #ifdef CONFIG_MIPS_MT_SMTC 62 extern void smtc_idle_loop_hook(void); 63 64 smtc_idle_loop_hook(); 65 #endif 66 67 if (cpu_wait) { 68 /* Don't trace irqs off for idle */ 69 stop_critical_timings(); 70 (*cpu_wait)(); 71 start_critical_timings(); 72 } 73 } 74 #ifdef CONFIG_HOTPLUG_CPU 75 if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) && 76 (system_state == SYSTEM_RUNNING || 77 system_state == SYSTEM_BOOTING)) 78 play_dead(); 79 #endif 80 tick_nohz_restart_sched_tick(); 81 preempt_enable_no_resched(); 82 schedule(); 83 preempt_disable(); 84 } 85 } 86 87 asmlinkage void ret_from_fork(void); 88 89 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 90 { 91 unsigned long status; 92 93 /* New thread loses kernel privileges. */ 94 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 95 #ifdef CONFIG_64BIT 96 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 97 #endif 98 status |= KU_USER; 99 regs->cp0_status = status; 100 clear_used_math(); 101 clear_fpu_owner(); 102 if (cpu_has_dsp) 103 __init_dsp(); 104 regs->cp0_epc = pc; 105 regs->regs[29] = sp; 106 current_thread_info()->addr_limit = USER_DS; 107 } 108 109 void exit_thread(void) 110 { 111 } 112 113 void flush_thread(void) 114 { 115 } 116 117 int copy_thread(unsigned long clone_flags, unsigned long usp, 118 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 119 { 120 struct thread_info *ti = task_thread_info(p); 121 struct pt_regs *childregs; 122 unsigned long childksp; 123 p->set_child_tid = p->clear_child_tid = NULL; 124 125 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 126 127 preempt_disable(); 128 129 if (is_fpu_owner()) 130 save_fp(p); 131 132 if (cpu_has_dsp) 133 save_dsp(p); 134 135 preempt_enable(); 136 137 /* set up new TSS. */ 138 childregs = (struct pt_regs *) childksp - 1; 139 /* Put the stack after the struct pt_regs. */ 140 childksp = (unsigned long) childregs; 141 *childregs = *regs; 142 childregs->regs[7] = 0; /* Clear error flag */ 143 144 childregs->regs[2] = 0; /* Child gets zero as return value */ 145 regs->regs[2] = p->pid; 146 147 if (childregs->cp0_status & ST0_CU0) { 148 childregs->regs[28] = (unsigned long) ti; 149 childregs->regs[29] = childksp; 150 ti->addr_limit = KERNEL_DS; 151 } else { 152 childregs->regs[29] = usp; 153 ti->addr_limit = USER_DS; 154 } 155 p->thread.reg29 = (unsigned long) childregs; 156 p->thread.reg31 = (unsigned long) ret_from_fork; 157 158 /* 159 * New tasks lose permission to use the fpu. This accelerates context 160 * switching for most programs since they don't use the fpu. 161 */ 162 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 163 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 164 165 #ifdef CONFIG_MIPS_MT_SMTC 166 /* 167 * SMTC restores TCStatus after Status, and the CU bits 168 * are aliased there. 169 */ 170 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 171 #endif 172 clear_tsk_thread_flag(p, TIF_USEDFPU); 173 174 #ifdef CONFIG_MIPS_MT_FPAFF 175 clear_tsk_thread_flag(p, TIF_FPUBOUND); 176 #endif /* CONFIG_MIPS_MT_FPAFF */ 177 178 if (clone_flags & CLONE_SETTLS) 179 ti->tp_value = regs->regs[7]; 180 181 return 0; 182 } 183 184 /* Fill in the fpu structure for a core dump.. */ 185 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 186 { 187 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 188 189 return 1; 190 } 191 192 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 193 { 194 int i; 195 196 for (i = 0; i < EF_R0; i++) 197 gp[i] = 0; 198 gp[EF_R0] = 0; 199 for (i = 1; i <= 31; i++) 200 gp[EF_R0 + i] = regs->regs[i]; 201 gp[EF_R26] = 0; 202 gp[EF_R27] = 0; 203 gp[EF_LO] = regs->lo; 204 gp[EF_HI] = regs->hi; 205 gp[EF_CP0_EPC] = regs->cp0_epc; 206 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 207 gp[EF_CP0_STATUS] = regs->cp0_status; 208 gp[EF_CP0_CAUSE] = regs->cp0_cause; 209 #ifdef EF_UNUSED0 210 gp[EF_UNUSED0] = 0; 211 #endif 212 } 213 214 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 215 { 216 elf_dump_regs(*regs, task_pt_regs(tsk)); 217 return 1; 218 } 219 220 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 221 { 222 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 223 224 return 1; 225 } 226 227 /* 228 * Create a kernel thread 229 */ 230 static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) 231 { 232 do_exit(fn(arg)); 233 } 234 235 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 236 { 237 struct pt_regs regs; 238 239 memset(®s, 0, sizeof(regs)); 240 241 regs.regs[4] = (unsigned long) arg; 242 regs.regs[5] = (unsigned long) fn; 243 regs.cp0_epc = (unsigned long) kernel_thread_helper; 244 regs.cp0_status = read_c0_status(); 245 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 246 regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 247 ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); 248 #else 249 regs.cp0_status |= ST0_EXL; 250 #endif 251 252 /* Ok, create the new process.. */ 253 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 254 } 255 256 /* 257 * 258 */ 259 struct mips_frame_info { 260 void *func; 261 unsigned long func_size; 262 int frame_size; 263 int pc_offset; 264 }; 265 266 static inline int is_ra_save_ins(union mips_instruction *ip) 267 { 268 /* sw / sd $ra, offset($sp) */ 269 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 270 ip->i_format.rs == 29 && 271 ip->i_format.rt == 31; 272 } 273 274 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 275 { 276 if (ip->j_format.opcode == jal_op) 277 return 1; 278 if (ip->r_format.opcode != spec_op) 279 return 0; 280 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 281 } 282 283 static inline int is_sp_move_ins(union mips_instruction *ip) 284 { 285 /* addiu/daddiu sp,sp,-imm */ 286 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 287 return 0; 288 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 289 return 1; 290 return 0; 291 } 292 293 static int get_frame_info(struct mips_frame_info *info) 294 { 295 union mips_instruction *ip = info->func; 296 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 297 unsigned i; 298 299 info->pc_offset = -1; 300 info->frame_size = 0; 301 302 if (!ip) 303 goto err; 304 305 if (max_insns == 0) 306 max_insns = 128U; /* unknown function size */ 307 max_insns = min(128U, max_insns); 308 309 for (i = 0; i < max_insns; i++, ip++) { 310 311 if (is_jal_jalr_jr_ins(ip)) 312 break; 313 if (!info->frame_size) { 314 if (is_sp_move_ins(ip)) 315 info->frame_size = - ip->i_format.simmediate; 316 continue; 317 } 318 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 319 info->pc_offset = 320 ip->i_format.simmediate / sizeof(long); 321 break; 322 } 323 } 324 if (info->frame_size && info->pc_offset >= 0) /* nested */ 325 return 0; 326 if (info->pc_offset < 0) /* leaf */ 327 return 1; 328 /* prologue seems boggus... */ 329 err: 330 return -1; 331 } 332 333 static struct mips_frame_info schedule_mfi __read_mostly; 334 335 static int __init frame_info_init(void) 336 { 337 unsigned long size = 0; 338 #ifdef CONFIG_KALLSYMS 339 unsigned long ofs; 340 341 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 342 #endif 343 schedule_mfi.func = schedule; 344 schedule_mfi.func_size = size; 345 346 get_frame_info(&schedule_mfi); 347 348 /* 349 * Without schedule() frame info, result given by 350 * thread_saved_pc() and get_wchan() are not reliable. 351 */ 352 if (schedule_mfi.pc_offset < 0) 353 printk("Can't analyze schedule() prologue at %p\n", schedule); 354 355 return 0; 356 } 357 358 arch_initcall(frame_info_init); 359 360 /* 361 * Return saved PC of a blocked thread. 362 */ 363 unsigned long thread_saved_pc(struct task_struct *tsk) 364 { 365 struct thread_struct *t = &tsk->thread; 366 367 /* New born processes are a special case */ 368 if (t->reg31 == (unsigned long) ret_from_fork) 369 return t->reg31; 370 if (schedule_mfi.pc_offset < 0) 371 return 0; 372 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 373 } 374 375 376 #ifdef CONFIG_KALLSYMS 377 /* used by show_backtrace() */ 378 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 379 unsigned long pc, unsigned long *ra) 380 { 381 unsigned long stack_page; 382 struct mips_frame_info info; 383 unsigned long size, ofs; 384 int leaf; 385 extern void ret_from_irq(void); 386 extern void ret_from_exception(void); 387 388 stack_page = (unsigned long)task_stack_page(task); 389 if (!stack_page) 390 return 0; 391 392 /* 393 * If we reached the bottom of interrupt context, 394 * return saved pc in pt_regs. 395 */ 396 if (pc == (unsigned long)ret_from_irq || 397 pc == (unsigned long)ret_from_exception) { 398 struct pt_regs *regs; 399 if (*sp >= stack_page && 400 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 401 regs = (struct pt_regs *)*sp; 402 pc = regs->cp0_epc; 403 if (__kernel_text_address(pc)) { 404 *sp = regs->regs[29]; 405 *ra = regs->regs[31]; 406 return pc; 407 } 408 } 409 return 0; 410 } 411 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 412 return 0; 413 /* 414 * Return ra if an exception occured at the first instruction 415 */ 416 if (unlikely(ofs == 0)) { 417 pc = *ra; 418 *ra = 0; 419 return pc; 420 } 421 422 info.func = (void *)(pc - ofs); 423 info.func_size = ofs; /* analyze from start to ofs */ 424 leaf = get_frame_info(&info); 425 if (leaf < 0) 426 return 0; 427 428 if (*sp < stack_page || 429 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 430 return 0; 431 432 if (leaf) 433 /* 434 * For some extreme cases, get_frame_info() can 435 * consider wrongly a nested function as a leaf 436 * one. In that cases avoid to return always the 437 * same value. 438 */ 439 pc = pc != *ra ? *ra : 0; 440 else 441 pc = ((unsigned long *)(*sp))[info.pc_offset]; 442 443 *sp += info.frame_size; 444 *ra = 0; 445 return __kernel_text_address(pc) ? pc : 0; 446 } 447 #endif 448 449 /* 450 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 451 */ 452 unsigned long get_wchan(struct task_struct *task) 453 { 454 unsigned long pc = 0; 455 #ifdef CONFIG_KALLSYMS 456 unsigned long sp; 457 unsigned long ra = 0; 458 #endif 459 460 if (!task || task == current || task->state == TASK_RUNNING) 461 goto out; 462 if (!task_stack_page(task)) 463 goto out; 464 465 pc = thread_saved_pc(task); 466 467 #ifdef CONFIG_KALLSYMS 468 sp = task->thread.reg29 + schedule_mfi.frame_size; 469 470 while (in_sched_functions(pc)) 471 pc = unwind_stack(task, &sp, pc, &ra); 472 #endif 473 474 out: 475 return pc; 476 } 477 478 /* 479 * Don't forget that the stack pointer must be aligned on a 8 bytes 480 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 481 */ 482 unsigned long arch_align_stack(unsigned long sp) 483 { 484 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 485 sp -= get_random_int() & ~PAGE_MASK; 486 487 return sp & ALMASK; 488 } 489