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/kernel.h> 15 #include <linux/mm.h> 16 #include <linux/stddef.h> 17 #include <linux/unistd.h> 18 #include <linux/ptrace.h> 19 #include <linux/slab.h> 20 #include <linux/mman.h> 21 #include <linux/personality.h> 22 #include <linux/sys.h> 23 #include <linux/user.h> 24 #include <linux/a.out.h> 25 #include <linux/init.h> 26 #include <linux/completion.h> 27 #include <linux/kallsyms.h> 28 29 #include <asm/abi.h> 30 #include <asm/bootinfo.h> 31 #include <asm/cpu.h> 32 #include <asm/dsp.h> 33 #include <asm/fpu.h> 34 #include <asm/pgtable.h> 35 #include <asm/system.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 #ifdef CONFIG_MIPS_MT_SMTC 45 #include <asm/mipsmtregs.h> 46 extern void smtc_idle_loop_hook(void); 47 #endif /* CONFIG_MIPS_MT_SMTC */ 48 49 /* 50 * The idle thread. There's no useful work to be done, so just try to conserve 51 * power and have a low exit latency (ie sit in a loop waiting for somebody to 52 * say that they'd like to reschedule) 53 */ 54 ATTRIB_NORET void cpu_idle(void) 55 { 56 /* endless idle loop with no priority at all */ 57 while (1) { 58 while (!need_resched()) { 59 #ifdef CONFIG_MIPS_MT_SMTC 60 smtc_idle_loop_hook(); 61 #endif /* CONFIG_MIPS_MT_SMTC */ 62 if (cpu_wait) 63 (*cpu_wait)(); 64 } 65 preempt_enable_no_resched(); 66 schedule(); 67 preempt_disable(); 68 } 69 } 70 71 /* 72 * Native o32 and N64 ABI without DSP ASE 73 */ 74 struct mips_abi mips_abi = { 75 .do_signal = do_signal, 76 #ifdef CONFIG_TRAD_SIGNALS 77 .setup_frame = setup_frame, 78 #endif 79 .setup_rt_frame = setup_rt_frame 80 }; 81 82 #ifdef CONFIG_MIPS32_O32 83 /* 84 * o32 compatibility on 64-bit kernels, without DSP ASE 85 */ 86 struct mips_abi mips_abi_32 = { 87 .do_signal = do_signal32, 88 .setup_frame = setup_frame_32, 89 .setup_rt_frame = setup_rt_frame_32 90 }; 91 #endif /* CONFIG_MIPS32_O32 */ 92 93 #ifdef CONFIG_MIPS32_N32 94 /* 95 * N32 on 64-bit kernels, without DSP ASE 96 */ 97 struct mips_abi mips_abi_n32 = { 98 .do_signal = do_signal, 99 .setup_rt_frame = setup_rt_frame_n32 100 }; 101 #endif /* CONFIG_MIPS32_N32 */ 102 103 asmlinkage void ret_from_fork(void); 104 105 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 106 { 107 unsigned long status; 108 109 /* New thread loses kernel privileges. */ 110 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK); 111 #ifdef CONFIG_64BIT 112 status &= ~ST0_FR; 113 status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR; 114 #endif 115 status |= KU_USER; 116 regs->cp0_status = status; 117 clear_used_math(); 118 clear_fpu_owner(); 119 if (cpu_has_dsp) 120 __init_dsp(); 121 regs->cp0_epc = pc; 122 regs->regs[29] = sp; 123 current_thread_info()->addr_limit = USER_DS; 124 } 125 126 void exit_thread(void) 127 { 128 } 129 130 void flush_thread(void) 131 { 132 } 133 134 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 135 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 136 { 137 struct thread_info *ti = task_thread_info(p); 138 struct pt_regs *childregs; 139 long childksp; 140 p->set_child_tid = p->clear_child_tid = NULL; 141 142 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 143 144 preempt_disable(); 145 146 if (is_fpu_owner()) 147 save_fp(p); 148 149 if (cpu_has_dsp) 150 save_dsp(p); 151 152 preempt_enable(); 153 154 /* set up new TSS. */ 155 childregs = (struct pt_regs *) childksp - 1; 156 *childregs = *regs; 157 childregs->regs[7] = 0; /* Clear error flag */ 158 159 #if defined(CONFIG_BINFMT_IRIX) 160 if (current->personality != PER_LINUX) { 161 /* Under IRIX things are a little different. */ 162 childregs->regs[3] = 1; 163 regs->regs[3] = 0; 164 } 165 #endif 166 childregs->regs[2] = 0; /* Child gets zero as return value */ 167 regs->regs[2] = p->pid; 168 169 if (childregs->cp0_status & ST0_CU0) { 170 childregs->regs[28] = (unsigned long) ti; 171 childregs->regs[29] = childksp; 172 ti->addr_limit = KERNEL_DS; 173 } else { 174 childregs->regs[29] = usp; 175 ti->addr_limit = USER_DS; 176 } 177 p->thread.reg29 = (unsigned long) childregs; 178 p->thread.reg31 = (unsigned long) ret_from_fork; 179 180 /* 181 * New tasks lose permission to use the fpu. This accelerates context 182 * switching for most programs since they don't use the fpu. 183 */ 184 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 185 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 186 clear_tsk_thread_flag(p, TIF_USEDFPU); 187 188 #ifdef CONFIG_MIPS_MT_FPAFF 189 /* 190 * FPU affinity support is cleaner if we track the 191 * user-visible CPU affinity from the very beginning. 192 * The generic cpus_allowed mask will already have 193 * been copied from the parent before copy_thread 194 * is invoked. 195 */ 196 p->thread.user_cpus_allowed = p->cpus_allowed; 197 #endif /* CONFIG_MIPS_MT_FPAFF */ 198 199 if (clone_flags & CLONE_SETTLS) 200 ti->tp_value = regs->regs[7]; 201 202 return 0; 203 } 204 205 /* Fill in the fpu structure for a core dump.. */ 206 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 207 { 208 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 209 210 return 1; 211 } 212 213 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 214 { 215 int i; 216 217 for (i = 0; i < EF_R0; i++) 218 gp[i] = 0; 219 gp[EF_R0] = 0; 220 for (i = 1; i <= 31; i++) 221 gp[EF_R0 + i] = regs->regs[i]; 222 gp[EF_R26] = 0; 223 gp[EF_R27] = 0; 224 gp[EF_LO] = regs->lo; 225 gp[EF_HI] = regs->hi; 226 gp[EF_CP0_EPC] = regs->cp0_epc; 227 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 228 gp[EF_CP0_STATUS] = regs->cp0_status; 229 gp[EF_CP0_CAUSE] = regs->cp0_cause; 230 #ifdef EF_UNUSED0 231 gp[EF_UNUSED0] = 0; 232 #endif 233 } 234 235 int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs) 236 { 237 elf_dump_regs(*regs, task_pt_regs(tsk)); 238 return 1; 239 } 240 241 int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr) 242 { 243 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 244 245 return 1; 246 } 247 248 /* 249 * Create a kernel thread 250 */ 251 ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *)) 252 { 253 do_exit(fn(arg)); 254 } 255 256 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 257 { 258 struct pt_regs regs; 259 260 memset(®s, 0, sizeof(regs)); 261 262 regs.regs[4] = (unsigned long) arg; 263 regs.regs[5] = (unsigned long) fn; 264 regs.cp0_epc = (unsigned long) kernel_thread_helper; 265 regs.cp0_status = read_c0_status(); 266 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 267 regs.cp0_status &= ~(ST0_KUP | ST0_IEC); 268 regs.cp0_status |= ST0_IEP; 269 #else 270 regs.cp0_status |= ST0_EXL; 271 #endif 272 273 /* Ok, create the new process.. */ 274 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 275 } 276 277 /* 278 * 279 */ 280 struct mips_frame_info { 281 void *func; 282 unsigned long func_size; 283 int frame_size; 284 int pc_offset; 285 }; 286 287 static inline int is_ra_save_ins(union mips_instruction *ip) 288 { 289 /* sw / sd $ra, offset($sp) */ 290 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 291 ip->i_format.rs == 29 && 292 ip->i_format.rt == 31; 293 } 294 295 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 296 { 297 if (ip->j_format.opcode == jal_op) 298 return 1; 299 if (ip->r_format.opcode != spec_op) 300 return 0; 301 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 302 } 303 304 static inline int is_sp_move_ins(union mips_instruction *ip) 305 { 306 /* addiu/daddiu sp,sp,-imm */ 307 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 308 return 0; 309 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 310 return 1; 311 return 0; 312 } 313 314 static int get_frame_info(struct mips_frame_info *info) 315 { 316 union mips_instruction *ip = info->func; 317 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 318 unsigned i; 319 320 info->pc_offset = -1; 321 info->frame_size = 0; 322 323 if (!ip) 324 goto err; 325 326 if (max_insns == 0) 327 max_insns = 128U; /* unknown function size */ 328 max_insns = min(128U, max_insns); 329 330 for (i = 0; i < max_insns; i++, ip++) { 331 332 if (is_jal_jalr_jr_ins(ip)) 333 break; 334 if (!info->frame_size) { 335 if (is_sp_move_ins(ip)) 336 info->frame_size = - ip->i_format.simmediate; 337 continue; 338 } 339 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 340 info->pc_offset = 341 ip->i_format.simmediate / sizeof(long); 342 break; 343 } 344 } 345 if (info->frame_size && info->pc_offset >= 0) /* nested */ 346 return 0; 347 if (info->pc_offset < 0) /* leaf */ 348 return 1; 349 /* prologue seems boggus... */ 350 err: 351 return -1; 352 } 353 354 static struct mips_frame_info schedule_mfi __read_mostly; 355 356 static int __init frame_info_init(void) 357 { 358 unsigned long size = 0; 359 #ifdef CONFIG_KALLSYMS 360 unsigned long ofs; 361 362 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 363 #endif 364 schedule_mfi.func = schedule; 365 schedule_mfi.func_size = size; 366 367 get_frame_info(&schedule_mfi); 368 369 /* 370 * Without schedule() frame info, result given by 371 * thread_saved_pc() and get_wchan() are not reliable. 372 */ 373 if (schedule_mfi.pc_offset < 0) 374 printk("Can't analyze schedule() prologue at %p\n", schedule); 375 376 return 0; 377 } 378 379 arch_initcall(frame_info_init); 380 381 /* 382 * Return saved PC of a blocked thread. 383 */ 384 unsigned long thread_saved_pc(struct task_struct *tsk) 385 { 386 struct thread_struct *t = &tsk->thread; 387 388 /* New born processes are a special case */ 389 if (t->reg31 == (unsigned long) ret_from_fork) 390 return t->reg31; 391 if (schedule_mfi.pc_offset < 0) 392 return 0; 393 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 394 } 395 396 397 #ifdef CONFIG_KALLSYMS 398 /* used by show_backtrace() */ 399 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 400 unsigned long pc, unsigned long *ra) 401 { 402 unsigned long stack_page; 403 struct mips_frame_info info; 404 unsigned long size, ofs; 405 int leaf; 406 extern void ret_from_irq(void); 407 extern void ret_from_exception(void); 408 409 stack_page = (unsigned long)task_stack_page(task); 410 if (!stack_page) 411 return 0; 412 413 /* 414 * If we reached the bottom of interrupt context, 415 * return saved pc in pt_regs. 416 */ 417 if (pc == (unsigned long)ret_from_irq || 418 pc == (unsigned long)ret_from_exception) { 419 struct pt_regs *regs; 420 if (*sp >= stack_page && 421 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 422 regs = (struct pt_regs *)*sp; 423 pc = regs->cp0_epc; 424 if (__kernel_text_address(pc)) { 425 *sp = regs->regs[29]; 426 *ra = regs->regs[31]; 427 return pc; 428 } 429 } 430 return 0; 431 } 432 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 433 return 0; 434 /* 435 * Return ra if an exception occured at the first instruction 436 */ 437 if (unlikely(ofs == 0)) { 438 pc = *ra; 439 *ra = 0; 440 return pc; 441 } 442 443 info.func = (void *)(pc - ofs); 444 info.func_size = ofs; /* analyze from start to ofs */ 445 leaf = get_frame_info(&info); 446 if (leaf < 0) 447 return 0; 448 449 if (*sp < stack_page || 450 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 451 return 0; 452 453 if (leaf) 454 /* 455 * For some extreme cases, get_frame_info() can 456 * consider wrongly a nested function as a leaf 457 * one. In that cases avoid to return always the 458 * same value. 459 */ 460 pc = pc != *ra ? *ra : 0; 461 else 462 pc = ((unsigned long *)(*sp))[info.pc_offset]; 463 464 *sp += info.frame_size; 465 *ra = 0; 466 return __kernel_text_address(pc) ? pc : 0; 467 } 468 #endif 469 470 /* 471 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 472 */ 473 unsigned long get_wchan(struct task_struct *task) 474 { 475 unsigned long pc = 0; 476 #ifdef CONFIG_KALLSYMS 477 unsigned long sp; 478 unsigned long ra = 0; 479 #endif 480 481 if (!task || task == current || task->state == TASK_RUNNING) 482 goto out; 483 if (!task_stack_page(task)) 484 goto out; 485 486 pc = thread_saved_pc(task); 487 488 #ifdef CONFIG_KALLSYMS 489 sp = task->thread.reg29 + schedule_mfi.frame_size; 490 491 while (in_sched_functions(pc)) 492 pc = unwind_stack(task, &sp, pc, &ra); 493 #endif 494 495 out: 496 return pc; 497 } 498