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