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|KU_MASK); 81 #ifdef CONFIG_64BIT 82 status &= ~ST0_FR; 83 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 84 #endif 85 status |= KU_USER; 86 regs->cp0_status = status; 87 clear_used_math(); 88 clear_fpu_owner(); 89 if (cpu_has_dsp) 90 __init_dsp(); 91 regs->cp0_epc = pc; 92 regs->regs[29] = sp; 93 current_thread_info()->addr_limit = USER_DS; 94 } 95 96 void exit_thread(void) 97 { 98 } 99 100 void flush_thread(void) 101 { 102 } 103 104 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 105 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 106 { 107 struct thread_info *ti = task_thread_info(p); 108 struct pt_regs *childregs; 109 long childksp; 110 p->set_child_tid = p->clear_child_tid = NULL; 111 112 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 113 114 preempt_disable(); 115 116 if (is_fpu_owner()) 117 save_fp(p); 118 119 if (cpu_has_dsp) 120 save_dsp(p); 121 122 preempt_enable(); 123 124 /* set up new TSS. */ 125 childregs = (struct pt_regs *) childksp - 1; 126 *childregs = *regs; 127 childregs->regs[7] = 0; /* Clear error flag */ 128 129 #if defined(CONFIG_BINFMT_IRIX) 130 if (current->personality != PER_LINUX) { 131 /* Under IRIX things are a little different. */ 132 childregs->regs[3] = 1; 133 regs->regs[3] = 0; 134 } 135 #endif 136 childregs->regs[2] = 0; /* Child gets zero as return value */ 137 regs->regs[2] = p->pid; 138 139 if (childregs->cp0_status & ST0_CU0) { 140 childregs->regs[28] = (unsigned long) ti; 141 childregs->regs[29] = childksp; 142 ti->addr_limit = KERNEL_DS; 143 } else { 144 childregs->regs[29] = usp; 145 ti->addr_limit = USER_DS; 146 } 147 p->thread.reg29 = (unsigned long) childregs; 148 p->thread.reg31 = (unsigned long) ret_from_fork; 149 150 /* 151 * New tasks lose permission to use the fpu. This accelerates context 152 * switching for most programs since they don't use the fpu. 153 */ 154 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 155 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 156 clear_tsk_thread_flag(p, TIF_USEDFPU); 157 158 #ifdef CONFIG_MIPS_MT_FPAFF 159 /* 160 * FPU affinity support is cleaner if we track the 161 * user-visible CPU affinity from the very beginning. 162 * The generic cpus_allowed mask will already have 163 * been copied from the parent before copy_thread 164 * is invoked. 165 */ 166 p->thread.user_cpus_allowed = p->cpus_allowed; 167 #endif /* CONFIG_MIPS_MT_FPAFF */ 168 169 if (clone_flags & CLONE_SETTLS) 170 ti->tp_value = regs->regs[7]; 171 172 return 0; 173 } 174 175 /* Fill in the fpu structure for a core dump.. */ 176 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 177 { 178 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 179 180 return 1; 181 } 182 183 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 184 { 185 int i; 186 187 for (i = 0; i < EF_R0; i++) 188 gp[i] = 0; 189 gp[EF_R0] = 0; 190 for (i = 1; i <= 31; i++) 191 gp[EF_R0 + i] = regs->regs[i]; 192 gp[EF_R26] = 0; 193 gp[EF_R27] = 0; 194 gp[EF_LO] = regs->lo; 195 gp[EF_HI] = regs->hi; 196 gp[EF_CP0_EPC] = regs->cp0_epc; 197 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 198 gp[EF_CP0_STATUS] = regs->cp0_status; 199 gp[EF_CP0_CAUSE] = regs->cp0_cause; 200 #ifdef EF_UNUSED0 201 gp[EF_UNUSED0] = 0; 202 #endif 203 } 204 205 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 206 { 207 elf_dump_regs(*regs, task_pt_regs(tsk)); 208 return 1; 209 } 210 211 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 212 { 213 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 214 215 return 1; 216 } 217 218 /* 219 * Create a kernel thread 220 */ 221 static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) 222 { 223 do_exit(fn(arg)); 224 } 225 226 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 227 { 228 struct pt_regs regs; 229 230 memset(®s, 0, sizeof(regs)); 231 232 regs.regs[4] = (unsigned long) arg; 233 regs.regs[5] = (unsigned long) fn; 234 regs.cp0_epc = (unsigned long) kernel_thread_helper; 235 regs.cp0_status = read_c0_status(); 236 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 237 regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 238 ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); 239 #else 240 regs.cp0_status |= ST0_EXL; 241 #endif 242 243 /* Ok, create the new process.. */ 244 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 245 } 246 247 /* 248 * 249 */ 250 struct mips_frame_info { 251 void *func; 252 unsigned long func_size; 253 int frame_size; 254 int pc_offset; 255 }; 256 257 static inline int is_ra_save_ins(union mips_instruction *ip) 258 { 259 /* sw / sd $ra, offset($sp) */ 260 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 261 ip->i_format.rs == 29 && 262 ip->i_format.rt == 31; 263 } 264 265 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 266 { 267 if (ip->j_format.opcode == jal_op) 268 return 1; 269 if (ip->r_format.opcode != spec_op) 270 return 0; 271 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 272 } 273 274 static inline int is_sp_move_ins(union mips_instruction *ip) 275 { 276 /* addiu/daddiu sp,sp,-imm */ 277 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 278 return 0; 279 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 280 return 1; 281 return 0; 282 } 283 284 static int get_frame_info(struct mips_frame_info *info) 285 { 286 union mips_instruction *ip = info->func; 287 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 288 unsigned i; 289 290 info->pc_offset = -1; 291 info->frame_size = 0; 292 293 if (!ip) 294 goto err; 295 296 if (max_insns == 0) 297 max_insns = 128U; /* unknown function size */ 298 max_insns = min(128U, max_insns); 299 300 for (i = 0; i < max_insns; i++, ip++) { 301 302 if (is_jal_jalr_jr_ins(ip)) 303 break; 304 if (!info->frame_size) { 305 if (is_sp_move_ins(ip)) 306 info->frame_size = - ip->i_format.simmediate; 307 continue; 308 } 309 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 310 info->pc_offset = 311 ip->i_format.simmediate / sizeof(long); 312 break; 313 } 314 } 315 if (info->frame_size && info->pc_offset >= 0) /* nested */ 316 return 0; 317 if (info->pc_offset < 0) /* leaf */ 318 return 1; 319 /* prologue seems boggus... */ 320 err: 321 return -1; 322 } 323 324 static struct mips_frame_info schedule_mfi __read_mostly; 325 326 static int __init frame_info_init(void) 327 { 328 unsigned long size = 0; 329 #ifdef CONFIG_KALLSYMS 330 unsigned long ofs; 331 332 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 333 #endif 334 schedule_mfi.func = schedule; 335 schedule_mfi.func_size = size; 336 337 get_frame_info(&schedule_mfi); 338 339 /* 340 * Without schedule() frame info, result given by 341 * thread_saved_pc() and get_wchan() are not reliable. 342 */ 343 if (schedule_mfi.pc_offset < 0) 344 printk("Can't analyze schedule() prologue at %p\n", schedule); 345 346 return 0; 347 } 348 349 arch_initcall(frame_info_init); 350 351 /* 352 * Return saved PC of a blocked thread. 353 */ 354 unsigned long thread_saved_pc(struct task_struct *tsk) 355 { 356 struct thread_struct *t = &tsk->thread; 357 358 /* New born processes are a special case */ 359 if (t->reg31 == (unsigned long) ret_from_fork) 360 return t->reg31; 361 if (schedule_mfi.pc_offset < 0) 362 return 0; 363 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 364 } 365 366 367 #ifdef CONFIG_KALLSYMS 368 /* used by show_backtrace() */ 369 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 370 unsigned long pc, unsigned long *ra) 371 { 372 unsigned long stack_page; 373 struct mips_frame_info info; 374 unsigned long size, ofs; 375 int leaf; 376 extern void ret_from_irq(void); 377 extern void ret_from_exception(void); 378 379 stack_page = (unsigned long)task_stack_page(task); 380 if (!stack_page) 381 return 0; 382 383 /* 384 * If we reached the bottom of interrupt context, 385 * return saved pc in pt_regs. 386 */ 387 if (pc == (unsigned long)ret_from_irq || 388 pc == (unsigned long)ret_from_exception) { 389 struct pt_regs *regs; 390 if (*sp >= stack_page && 391 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 392 regs = (struct pt_regs *)*sp; 393 pc = regs->cp0_epc; 394 if (__kernel_text_address(pc)) { 395 *sp = regs->regs[29]; 396 *ra = regs->regs[31]; 397 return pc; 398 } 399 } 400 return 0; 401 } 402 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 403 return 0; 404 /* 405 * Return ra if an exception occured at the first instruction 406 */ 407 if (unlikely(ofs == 0)) { 408 pc = *ra; 409 *ra = 0; 410 return pc; 411 } 412 413 info.func = (void *)(pc - ofs); 414 info.func_size = ofs; /* analyze from start to ofs */ 415 leaf = get_frame_info(&info); 416 if (leaf < 0) 417 return 0; 418 419 if (*sp < stack_page || 420 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 421 return 0; 422 423 if (leaf) 424 /* 425 * For some extreme cases, get_frame_info() can 426 * consider wrongly a nested function as a leaf 427 * one. In that cases avoid to return always the 428 * same value. 429 */ 430 pc = pc != *ra ? *ra : 0; 431 else 432 pc = ((unsigned long *)(*sp))[info.pc_offset]; 433 434 *sp += info.frame_size; 435 *ra = 0; 436 return __kernel_text_address(pc) ? pc : 0; 437 } 438 #endif 439 440 /* 441 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 442 */ 443 unsigned long get_wchan(struct task_struct *task) 444 { 445 unsigned long pc = 0; 446 #ifdef CONFIG_KALLSYMS 447 unsigned long sp; 448 unsigned long ra = 0; 449 #endif 450 451 if (!task || task == current || task->state == TASK_RUNNING) 452 goto out; 453 if (!task_stack_page(task)) 454 goto out; 455 456 pc = thread_saved_pc(task); 457 458 #ifdef CONFIG_KALLSYMS 459 sp = task->thread.reg29 + schedule_mfi.frame_size; 460 461 while (in_sched_functions(pc)) 462 pc = unwind_stack(task, &sp, pc, &ra); 463 #endif 464 465 out: 466 return pc; 467 } 468 469 /* 470 * Don't forget that the stack pointer must be aligned on a 8 bytes 471 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 472 */ 473 unsigned long arch_align_stack(unsigned long sp) 474 { 475 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 476 sp -= get_random_int() & ~PAGE_MASK; 477 478 return sp & ALMASK; 479 } 480