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