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