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/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(1); 57 while (!need_resched()) { 58 #ifdef CONFIG_MIPS_MT_SMTC 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 childregs->regs[2] = 0; /* Child gets zero as return value */ 129 regs->regs[2] = p->pid; 130 131 if (childregs->cp0_status & ST0_CU0) { 132 childregs->regs[28] = (unsigned long) ti; 133 childregs->regs[29] = childksp; 134 ti->addr_limit = KERNEL_DS; 135 } else { 136 childregs->regs[29] = usp; 137 ti->addr_limit = USER_DS; 138 } 139 p->thread.reg29 = (unsigned long) childregs; 140 p->thread.reg31 = (unsigned long) ret_from_fork; 141 142 /* 143 * New tasks lose permission to use the fpu. This accelerates context 144 * switching for most programs since they don't use the fpu. 145 */ 146 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 147 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 148 149 #ifdef CONFIG_MIPS_MT_SMTC 150 /* 151 * SMTC restores TCStatus after Status, and the CU bits 152 * are aliased there. 153 */ 154 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 155 #endif 156 clear_tsk_thread_flag(p, TIF_USEDFPU); 157 158 #ifdef CONFIG_MIPS_MT_FPAFF 159 clear_tsk_thread_flag(p, TIF_FPUBOUND); 160 #endif /* CONFIG_MIPS_MT_FPAFF */ 161 162 if (clone_flags & CLONE_SETTLS) 163 ti->tp_value = regs->regs[7]; 164 165 return 0; 166 } 167 168 /* Fill in the fpu structure for a core dump.. */ 169 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 170 { 171 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 172 173 return 1; 174 } 175 176 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 177 { 178 int i; 179 180 for (i = 0; i < EF_R0; i++) 181 gp[i] = 0; 182 gp[EF_R0] = 0; 183 for (i = 1; i <= 31; i++) 184 gp[EF_R0 + i] = regs->regs[i]; 185 gp[EF_R26] = 0; 186 gp[EF_R27] = 0; 187 gp[EF_LO] = regs->lo; 188 gp[EF_HI] = regs->hi; 189 gp[EF_CP0_EPC] = regs->cp0_epc; 190 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 191 gp[EF_CP0_STATUS] = regs->cp0_status; 192 gp[EF_CP0_CAUSE] = regs->cp0_cause; 193 #ifdef EF_UNUSED0 194 gp[EF_UNUSED0] = 0; 195 #endif 196 } 197 198 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 199 { 200 elf_dump_regs(*regs, task_pt_regs(tsk)); 201 return 1; 202 } 203 204 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 205 { 206 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 207 208 return 1; 209 } 210 211 /* 212 * Create a kernel thread 213 */ 214 static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) 215 { 216 do_exit(fn(arg)); 217 } 218 219 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 220 { 221 struct pt_regs regs; 222 223 memset(®s, 0, sizeof(regs)); 224 225 regs.regs[4] = (unsigned long) arg; 226 regs.regs[5] = (unsigned long) fn; 227 regs.cp0_epc = (unsigned long) kernel_thread_helper; 228 regs.cp0_status = read_c0_status(); 229 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 230 regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 231 ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); 232 #else 233 regs.cp0_status |= ST0_EXL; 234 #endif 235 236 /* Ok, create the new process.. */ 237 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 238 } 239 240 /* 241 * 242 */ 243 struct mips_frame_info { 244 void *func; 245 unsigned long func_size; 246 int frame_size; 247 int pc_offset; 248 }; 249 250 static inline int is_ra_save_ins(union mips_instruction *ip) 251 { 252 /* sw / sd $ra, offset($sp) */ 253 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 254 ip->i_format.rs == 29 && 255 ip->i_format.rt == 31; 256 } 257 258 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 259 { 260 if (ip->j_format.opcode == jal_op) 261 return 1; 262 if (ip->r_format.opcode != spec_op) 263 return 0; 264 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 265 } 266 267 static inline int is_sp_move_ins(union mips_instruction *ip) 268 { 269 /* addiu/daddiu sp,sp,-imm */ 270 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 271 return 0; 272 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 273 return 1; 274 return 0; 275 } 276 277 static int get_frame_info(struct mips_frame_info *info) 278 { 279 union mips_instruction *ip = info->func; 280 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 281 unsigned i; 282 283 info->pc_offset = -1; 284 info->frame_size = 0; 285 286 if (!ip) 287 goto err; 288 289 if (max_insns == 0) 290 max_insns = 128U; /* unknown function size */ 291 max_insns = min(128U, max_insns); 292 293 for (i = 0; i < max_insns; i++, ip++) { 294 295 if (is_jal_jalr_jr_ins(ip)) 296 break; 297 if (!info->frame_size) { 298 if (is_sp_move_ins(ip)) 299 info->frame_size = - ip->i_format.simmediate; 300 continue; 301 } 302 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 303 info->pc_offset = 304 ip->i_format.simmediate / sizeof(long); 305 break; 306 } 307 } 308 if (info->frame_size && info->pc_offset >= 0) /* nested */ 309 return 0; 310 if (info->pc_offset < 0) /* leaf */ 311 return 1; 312 /* prologue seems boggus... */ 313 err: 314 return -1; 315 } 316 317 static struct mips_frame_info schedule_mfi __read_mostly; 318 319 static int __init frame_info_init(void) 320 { 321 unsigned long size = 0; 322 #ifdef CONFIG_KALLSYMS 323 unsigned long ofs; 324 325 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 326 #endif 327 schedule_mfi.func = schedule; 328 schedule_mfi.func_size = size; 329 330 get_frame_info(&schedule_mfi); 331 332 /* 333 * Without schedule() frame info, result given by 334 * thread_saved_pc() and get_wchan() are not reliable. 335 */ 336 if (schedule_mfi.pc_offset < 0) 337 printk("Can't analyze schedule() prologue at %p\n", schedule); 338 339 return 0; 340 } 341 342 arch_initcall(frame_info_init); 343 344 /* 345 * Return saved PC of a blocked thread. 346 */ 347 unsigned long thread_saved_pc(struct task_struct *tsk) 348 { 349 struct thread_struct *t = &tsk->thread; 350 351 /* New born processes are a special case */ 352 if (t->reg31 == (unsigned long) ret_from_fork) 353 return t->reg31; 354 if (schedule_mfi.pc_offset < 0) 355 return 0; 356 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 357 } 358 359 360 #ifdef CONFIG_KALLSYMS 361 /* used by show_backtrace() */ 362 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 363 unsigned long pc, unsigned long *ra) 364 { 365 unsigned long stack_page; 366 struct mips_frame_info info; 367 unsigned long size, ofs; 368 int leaf; 369 extern void ret_from_irq(void); 370 extern void ret_from_exception(void); 371 372 stack_page = (unsigned long)task_stack_page(task); 373 if (!stack_page) 374 return 0; 375 376 /* 377 * If we reached the bottom of interrupt context, 378 * return saved pc in pt_regs. 379 */ 380 if (pc == (unsigned long)ret_from_irq || 381 pc == (unsigned long)ret_from_exception) { 382 struct pt_regs *regs; 383 if (*sp >= stack_page && 384 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 385 regs = (struct pt_regs *)*sp; 386 pc = regs->cp0_epc; 387 if (__kernel_text_address(pc)) { 388 *sp = regs->regs[29]; 389 *ra = regs->regs[31]; 390 return pc; 391 } 392 } 393 return 0; 394 } 395 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 396 return 0; 397 /* 398 * Return ra if an exception occured at the first instruction 399 */ 400 if (unlikely(ofs == 0)) { 401 pc = *ra; 402 *ra = 0; 403 return pc; 404 } 405 406 info.func = (void *)(pc - ofs); 407 info.func_size = ofs; /* analyze from start to ofs */ 408 leaf = get_frame_info(&info); 409 if (leaf < 0) 410 return 0; 411 412 if (*sp < stack_page || 413 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 414 return 0; 415 416 if (leaf) 417 /* 418 * For some extreme cases, get_frame_info() can 419 * consider wrongly a nested function as a leaf 420 * one. In that cases avoid to return always the 421 * same value. 422 */ 423 pc = pc != *ra ? *ra : 0; 424 else 425 pc = ((unsigned long *)(*sp))[info.pc_offset]; 426 427 *sp += info.frame_size; 428 *ra = 0; 429 return __kernel_text_address(pc) ? pc : 0; 430 } 431 #endif 432 433 /* 434 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 435 */ 436 unsigned long get_wchan(struct task_struct *task) 437 { 438 unsigned long pc = 0; 439 #ifdef CONFIG_KALLSYMS 440 unsigned long sp; 441 unsigned long ra = 0; 442 #endif 443 444 if (!task || task == current || task->state == TASK_RUNNING) 445 goto out; 446 if (!task_stack_page(task)) 447 goto out; 448 449 pc = thread_saved_pc(task); 450 451 #ifdef CONFIG_KALLSYMS 452 sp = task->thread.reg29 + schedule_mfi.frame_size; 453 454 while (in_sched_functions(pc)) 455 pc = unwind_stack(task, &sp, pc, &ra); 456 #endif 457 458 out: 459 return pc; 460 } 461 462 /* 463 * Don't forget that the stack pointer must be aligned on a 8 bytes 464 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 465 */ 466 unsigned long arch_align_stack(unsigned long sp) 467 { 468 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 469 sp -= get_random_int() & ~PAGE_MASK; 470 471 return sp & ALMASK; 472 } 473