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