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 * Copyright (C) 2013 Imagination Technologies Ltd. 11 */ 12 #include <linux/errno.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/export.h> 20 #include <linux/ptrace.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/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 #ifdef CONFIG_HOTPLUG_CPU 46 void arch_cpu_idle_dead(void) 47 { 48 /* What the heck is this check doing ? */ 49 if (!cpu_isset(smp_processor_id(), cpu_callin_map)) 50 play_dead(); 51 } 52 #endif 53 54 asmlinkage void ret_from_fork(void); 55 asmlinkage void ret_from_kernel_thread(void); 56 57 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 58 { 59 unsigned long status; 60 61 /* New thread loses kernel privileges. */ 62 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 63 #ifdef CONFIG_64BIT 64 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 65 #endif 66 status |= KU_USER; 67 regs->cp0_status = status; 68 clear_used_math(); 69 clear_fpu_owner(); 70 if (cpu_has_dsp) 71 __init_dsp(); 72 regs->cp0_epc = pc; 73 regs->regs[29] = sp; 74 } 75 76 void exit_thread(void) 77 { 78 } 79 80 void flush_thread(void) 81 { 82 } 83 84 int copy_thread(unsigned long clone_flags, unsigned long usp, 85 unsigned long arg, struct task_struct *p) 86 { 87 struct thread_info *ti = task_thread_info(p); 88 struct pt_regs *childregs, *regs = current_pt_regs(); 89 unsigned long childksp; 90 p->set_child_tid = p->clear_child_tid = NULL; 91 92 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 93 94 preempt_disable(); 95 96 if (is_fpu_owner()) 97 save_fp(p); 98 99 if (cpu_has_dsp) 100 save_dsp(p); 101 102 preempt_enable(); 103 104 /* set up new TSS. */ 105 childregs = (struct pt_regs *) childksp - 1; 106 /* Put the stack after the struct pt_regs. */ 107 childksp = (unsigned long) childregs; 108 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 109 if (unlikely(p->flags & PF_KTHREAD)) { 110 unsigned long status = p->thread.cp0_status; 111 memset(childregs, 0, sizeof(struct pt_regs)); 112 ti->addr_limit = KERNEL_DS; 113 p->thread.reg16 = usp; /* fn */ 114 p->thread.reg17 = arg; 115 p->thread.reg29 = childksp; 116 p->thread.reg31 = (unsigned long) ret_from_kernel_thread; 117 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 118 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 119 ((status & (ST0_KUC | ST0_IEC)) << 2); 120 #else 121 status |= ST0_EXL; 122 #endif 123 childregs->cp0_status = status; 124 return 0; 125 } 126 *childregs = *regs; 127 childregs->regs[7] = 0; /* Clear error flag */ 128 childregs->regs[2] = 0; /* Child gets zero as return value */ 129 if (usp) 130 childregs->regs[29] = usp; 131 ti->addr_limit = USER_DS; 132 133 p->thread.reg29 = (unsigned long) childregs; 134 p->thread.reg31 = (unsigned long) ret_from_fork; 135 136 /* 137 * New tasks lose permission to use the fpu. This accelerates context 138 * switching for most programs since they don't use the fpu. 139 */ 140 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 141 142 #ifdef CONFIG_MIPS_MT_SMTC 143 /* 144 * SMTC restores TCStatus after Status, and the CU bits 145 * are aliased there. 146 */ 147 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 148 #endif 149 clear_tsk_thread_flag(p, TIF_USEDFPU); 150 151 #ifdef CONFIG_MIPS_MT_FPAFF 152 clear_tsk_thread_flag(p, TIF_FPUBOUND); 153 #endif /* CONFIG_MIPS_MT_FPAFF */ 154 155 if (clone_flags & CLONE_SETTLS) 156 ti->tp_value = regs->regs[7]; 157 158 return 0; 159 } 160 161 /* Fill in the fpu structure for a core dump.. */ 162 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 163 { 164 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 165 166 return 1; 167 } 168 169 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 170 { 171 int i; 172 173 for (i = 0; i < EF_R0; i++) 174 gp[i] = 0; 175 gp[EF_R0] = 0; 176 for (i = 1; i <= 31; i++) 177 gp[EF_R0 + i] = regs->regs[i]; 178 gp[EF_R26] = 0; 179 gp[EF_R27] = 0; 180 gp[EF_LO] = regs->lo; 181 gp[EF_HI] = regs->hi; 182 gp[EF_CP0_EPC] = regs->cp0_epc; 183 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 184 gp[EF_CP0_STATUS] = regs->cp0_status; 185 gp[EF_CP0_CAUSE] = regs->cp0_cause; 186 #ifdef EF_UNUSED0 187 gp[EF_UNUSED0] = 0; 188 #endif 189 } 190 191 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 192 { 193 elf_dump_regs(*regs, task_pt_regs(tsk)); 194 return 1; 195 } 196 197 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 198 { 199 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 200 201 return 1; 202 } 203 204 /* 205 * 206 */ 207 struct mips_frame_info { 208 void *func; 209 unsigned long func_size; 210 int frame_size; 211 int pc_offset; 212 }; 213 214 #define J_TARGET(pc,target) \ 215 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) 216 217 static inline int is_ra_save_ins(union mips_instruction *ip) 218 { 219 #ifdef CONFIG_CPU_MICROMIPS 220 union mips_instruction mmi; 221 222 /* 223 * swsp ra,offset 224 * swm16 reglist,offset(sp) 225 * swm32 reglist,offset(sp) 226 * sw32 ra,offset(sp) 227 * jradiussp - NOT SUPPORTED 228 * 229 * microMIPS is way more fun... 230 */ 231 if (mm_insn_16bit(ip->halfword[0])) { 232 mmi.word = (ip->halfword[0] << 16); 233 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op && 234 mmi.mm16_r5_format.rt == 31) || 235 (mmi.mm16_m_format.opcode == mm_pool16c_op && 236 mmi.mm16_m_format.func == mm_swm16_op)); 237 } 238 else { 239 mmi.halfword[0] = ip->halfword[1]; 240 mmi.halfword[1] = ip->halfword[0]; 241 return ((mmi.mm_m_format.opcode == mm_pool32b_op && 242 mmi.mm_m_format.rd > 9 && 243 mmi.mm_m_format.base == 29 && 244 mmi.mm_m_format.func == mm_swm32_func) || 245 (mmi.i_format.opcode == mm_sw32_op && 246 mmi.i_format.rs == 29 && 247 mmi.i_format.rt == 31)); 248 } 249 #else 250 /* sw / sd $ra, offset($sp) */ 251 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 252 ip->i_format.rs == 29 && 253 ip->i_format.rt == 31; 254 #endif 255 } 256 257 static inline int is_jump_ins(union mips_instruction *ip) 258 { 259 #ifdef CONFIG_CPU_MICROMIPS 260 /* 261 * jr16,jrc,jalr16,jalr16 262 * jal 263 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb 264 * jraddiusp - NOT SUPPORTED 265 * 266 * microMIPS is kind of more fun... 267 */ 268 union mips_instruction mmi; 269 270 mmi.word = (ip->halfword[0] << 16); 271 272 if ((mmi.mm16_r5_format.opcode == mm_pool16c_op && 273 (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) || 274 ip->j_format.opcode == mm_jal32_op) 275 return 1; 276 if (ip->r_format.opcode != mm_pool32a_op || 277 ip->r_format.func != mm_pool32axf_op) 278 return 0; 279 return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op); 280 #else 281 if (ip->j_format.opcode == j_op) 282 return 1; 283 if (ip->j_format.opcode == jal_op) 284 return 1; 285 if (ip->r_format.opcode != spec_op) 286 return 0; 287 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 288 #endif 289 } 290 291 static inline int is_sp_move_ins(union mips_instruction *ip) 292 { 293 #ifdef CONFIG_CPU_MICROMIPS 294 /* 295 * addiusp -imm 296 * addius5 sp,-imm 297 * addiu32 sp,sp,-imm 298 * jradiussp - NOT SUPPORTED 299 * 300 * microMIPS is not more fun... 301 */ 302 if (mm_insn_16bit(ip->halfword[0])) { 303 union mips_instruction mmi; 304 305 mmi.word = (ip->halfword[0] << 16); 306 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op && 307 mmi.mm16_r3_format.simmediate && mm_addiusp_func) || 308 (mmi.mm16_r5_format.opcode == mm_pool16d_op && 309 mmi.mm16_r5_format.rt == 29)); 310 } 311 return (ip->mm_i_format.opcode == mm_addiu32_op && 312 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29); 313 #else 314 /* addiu/daddiu sp,sp,-imm */ 315 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 316 return 0; 317 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 318 return 1; 319 #endif 320 return 0; 321 } 322 323 static int get_frame_info(struct mips_frame_info *info) 324 { 325 #ifdef CONFIG_CPU_MICROMIPS 326 union mips_instruction *ip = (void *) (((char *) info->func) - 1); 327 #else 328 union mips_instruction *ip = info->func; 329 #endif 330 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 331 unsigned i; 332 333 info->pc_offset = -1; 334 info->frame_size = 0; 335 336 if (!ip) 337 goto err; 338 339 if (max_insns == 0) 340 max_insns = 128U; /* unknown function size */ 341 max_insns = min(128U, max_insns); 342 343 for (i = 0; i < max_insns; i++, ip++) { 344 345 if (is_jump_ins(ip)) 346 break; 347 if (!info->frame_size) { 348 if (is_sp_move_ins(ip)) 349 { 350 #ifdef CONFIG_CPU_MICROMIPS 351 if (mm_insn_16bit(ip->halfword[0])) 352 { 353 unsigned short tmp; 354 355 if (ip->halfword[0] & mm_addiusp_func) 356 { 357 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2); 358 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0)); 359 } else { 360 tmp = (ip->halfword[0] >> 1); 361 info->frame_size = -(signed short)(tmp & 0xf); 362 } 363 ip = (void *) &ip->halfword[1]; 364 ip--; 365 } else 366 #endif 367 info->frame_size = - ip->i_format.simmediate; 368 } 369 continue; 370 } 371 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 372 info->pc_offset = 373 ip->i_format.simmediate / sizeof(long); 374 break; 375 } 376 } 377 if (info->frame_size && info->pc_offset >= 0) /* nested */ 378 return 0; 379 if (info->pc_offset < 0) /* leaf */ 380 return 1; 381 /* prologue seems boggus... */ 382 err: 383 return -1; 384 } 385 386 static struct mips_frame_info schedule_mfi __read_mostly; 387 388 #ifdef CONFIG_KALLSYMS 389 static unsigned long get___schedule_addr(void) 390 { 391 return kallsyms_lookup_name("__schedule"); 392 } 393 #else 394 static unsigned long get___schedule_addr(void) 395 { 396 union mips_instruction *ip = (void *)schedule; 397 int max_insns = 8; 398 int i; 399 400 for (i = 0; i < max_insns; i++, ip++) { 401 if (ip->j_format.opcode == j_op) 402 return J_TARGET(ip, ip->j_format.target); 403 } 404 return 0; 405 } 406 #endif 407 408 static int __init frame_info_init(void) 409 { 410 unsigned long size = 0; 411 #ifdef CONFIG_KALLSYMS 412 unsigned long ofs; 413 #endif 414 unsigned long addr; 415 416 addr = get___schedule_addr(); 417 if (!addr) 418 addr = (unsigned long)schedule; 419 420 #ifdef CONFIG_KALLSYMS 421 kallsyms_lookup_size_offset(addr, &size, &ofs); 422 #endif 423 schedule_mfi.func = (void *)addr; 424 schedule_mfi.func_size = size; 425 426 get_frame_info(&schedule_mfi); 427 428 /* 429 * Without schedule() frame info, result given by 430 * thread_saved_pc() and get_wchan() are not reliable. 431 */ 432 if (schedule_mfi.pc_offset < 0) 433 printk("Can't analyze schedule() prologue at %p\n", schedule); 434 435 return 0; 436 } 437 438 arch_initcall(frame_info_init); 439 440 /* 441 * Return saved PC of a blocked thread. 442 */ 443 unsigned long thread_saved_pc(struct task_struct *tsk) 444 { 445 struct thread_struct *t = &tsk->thread; 446 447 /* New born processes are a special case */ 448 if (t->reg31 == (unsigned long) ret_from_fork) 449 return t->reg31; 450 if (schedule_mfi.pc_offset < 0) 451 return 0; 452 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 453 } 454 455 456 #ifdef CONFIG_KALLSYMS 457 /* generic stack unwinding function */ 458 unsigned long notrace unwind_stack_by_address(unsigned long stack_page, 459 unsigned long *sp, 460 unsigned long pc, 461 unsigned long *ra) 462 { 463 struct mips_frame_info info; 464 unsigned long size, ofs; 465 int leaf; 466 extern void ret_from_irq(void); 467 extern void ret_from_exception(void); 468 469 if (!stack_page) 470 return 0; 471 472 /* 473 * If we reached the bottom of interrupt context, 474 * return saved pc in pt_regs. 475 */ 476 if (pc == (unsigned long)ret_from_irq || 477 pc == (unsigned long)ret_from_exception) { 478 struct pt_regs *regs; 479 if (*sp >= stack_page && 480 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 481 regs = (struct pt_regs *)*sp; 482 pc = regs->cp0_epc; 483 if (__kernel_text_address(pc)) { 484 *sp = regs->regs[29]; 485 *ra = regs->regs[31]; 486 return pc; 487 } 488 } 489 return 0; 490 } 491 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 492 return 0; 493 /* 494 * Return ra if an exception occurred at the first instruction 495 */ 496 if (unlikely(ofs == 0)) { 497 pc = *ra; 498 *ra = 0; 499 return pc; 500 } 501 502 info.func = (void *)(pc - ofs); 503 info.func_size = ofs; /* analyze from start to ofs */ 504 leaf = get_frame_info(&info); 505 if (leaf < 0) 506 return 0; 507 508 if (*sp < stack_page || 509 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 510 return 0; 511 512 if (leaf) 513 /* 514 * For some extreme cases, get_frame_info() can 515 * consider wrongly a nested function as a leaf 516 * one. In that cases avoid to return always the 517 * same value. 518 */ 519 pc = pc != *ra ? *ra : 0; 520 else 521 pc = ((unsigned long *)(*sp))[info.pc_offset]; 522 523 *sp += info.frame_size; 524 *ra = 0; 525 return __kernel_text_address(pc) ? pc : 0; 526 } 527 EXPORT_SYMBOL(unwind_stack_by_address); 528 529 /* used by show_backtrace() */ 530 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 531 unsigned long pc, unsigned long *ra) 532 { 533 unsigned long stack_page = (unsigned long)task_stack_page(task); 534 return unwind_stack_by_address(stack_page, sp, pc, ra); 535 } 536 #endif 537 538 /* 539 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 540 */ 541 unsigned long get_wchan(struct task_struct *task) 542 { 543 unsigned long pc = 0; 544 #ifdef CONFIG_KALLSYMS 545 unsigned long sp; 546 unsigned long ra = 0; 547 #endif 548 549 if (!task || task == current || task->state == TASK_RUNNING) 550 goto out; 551 if (!task_stack_page(task)) 552 goto out; 553 554 pc = thread_saved_pc(task); 555 556 #ifdef CONFIG_KALLSYMS 557 sp = task->thread.reg29 + schedule_mfi.frame_size; 558 559 while (in_sched_functions(pc)) 560 pc = unwind_stack(task, &sp, pc, &ra); 561 #endif 562 563 out: 564 return pc; 565 } 566 567 /* 568 * Don't forget that the stack pointer must be aligned on a 8 bytes 569 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 570 */ 571 unsigned long arch_align_stack(unsigned long sp) 572 { 573 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 574 sp -= get_random_int() & ~PAGE_MASK; 575 576 return sp & ALMASK; 577 } 578