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 #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/system.h> 37 #include <asm/mipsregs.h> 38 #include <asm/processor.h> 39 #include <asm/uaccess.h> 40 #include <asm/io.h> 41 #include <asm/elf.h> 42 #include <asm/isadep.h> 43 #include <asm/inst.h> 44 #include <asm/stacktrace.h> 45 46 /* 47 * The idle thread. There's no useful work to be done, so just try to conserve 48 * power and have a low exit latency (ie sit in a loop waiting for somebody to 49 * say that they'd like to reschedule) 50 */ 51 void __noreturn cpu_idle(void) 52 { 53 /* endless idle loop with no priority at all */ 54 while (1) { 55 while (!need_resched()) { 56 #ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG 57 extern void smtc_idle_loop_hook(void); 58 59 smtc_idle_loop_hook(); 60 #endif 61 if (cpu_wait) 62 (*cpu_wait)(); 63 } 64 preempt_enable_no_resched(); 65 schedule(); 66 preempt_disable(); 67 } 68 } 69 70 asmlinkage void ret_from_fork(void); 71 72 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 73 { 74 unsigned long status; 75 76 /* New thread loses kernel privileges. */ 77 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK); 78 #ifdef CONFIG_64BIT 79 status &= ~ST0_FR; 80 status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR; 81 #endif 82 status |= KU_USER; 83 regs->cp0_status = status; 84 clear_used_math(); 85 clear_fpu_owner(); 86 if (cpu_has_dsp) 87 __init_dsp(); 88 regs->cp0_epc = pc; 89 regs->regs[29] = sp; 90 current_thread_info()->addr_limit = USER_DS; 91 } 92 93 void exit_thread(void) 94 { 95 } 96 97 void flush_thread(void) 98 { 99 } 100 101 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 102 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 103 { 104 struct thread_info *ti = task_thread_info(p); 105 struct pt_regs *childregs; 106 long childksp; 107 p->set_child_tid = p->clear_child_tid = NULL; 108 109 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 110 111 preempt_disable(); 112 113 if (is_fpu_owner()) 114 save_fp(p); 115 116 if (cpu_has_dsp) 117 save_dsp(p); 118 119 preempt_enable(); 120 121 /* set up new TSS. */ 122 childregs = (struct pt_regs *) childksp - 1; 123 *childregs = *regs; 124 childregs->regs[7] = 0; /* Clear error flag */ 125 126 #if defined(CONFIG_BINFMT_IRIX) 127 if (current->personality != PER_LINUX) { 128 /* Under IRIX things are a little different. */ 129 childregs->regs[3] = 1; 130 regs->regs[3] = 0; 131 } 132 #endif 133 childregs->regs[2] = 0; /* Child gets zero as return value */ 134 regs->regs[2] = p->pid; 135 136 if (childregs->cp0_status & ST0_CU0) { 137 childregs->regs[28] = (unsigned long) ti; 138 childregs->regs[29] = childksp; 139 ti->addr_limit = KERNEL_DS; 140 } else { 141 childregs->regs[29] = usp; 142 ti->addr_limit = USER_DS; 143 } 144 p->thread.reg29 = (unsigned long) childregs; 145 p->thread.reg31 = (unsigned long) ret_from_fork; 146 147 /* 148 * New tasks lose permission to use the fpu. This accelerates context 149 * switching for most programs since they don't use the fpu. 150 */ 151 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 152 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 153 clear_tsk_thread_flag(p, TIF_USEDFPU); 154 155 #ifdef CONFIG_MIPS_MT_FPAFF 156 /* 157 * FPU affinity support is cleaner if we track the 158 * user-visible CPU affinity from the very beginning. 159 * The generic cpus_allowed mask will already have 160 * been copied from the parent before copy_thread 161 * is invoked. 162 */ 163 p->thread.user_cpus_allowed = p->cpus_allowed; 164 #endif /* CONFIG_MIPS_MT_FPAFF */ 165 166 if (clone_flags & CLONE_SETTLS) 167 ti->tp_value = regs->regs[7]; 168 169 return 0; 170 } 171 172 /* Fill in the fpu structure for a core dump.. */ 173 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 174 { 175 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 176 177 return 1; 178 } 179 180 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 181 { 182 int i; 183 184 for (i = 0; i < EF_R0; i++) 185 gp[i] = 0; 186 gp[EF_R0] = 0; 187 for (i = 1; i <= 31; i++) 188 gp[EF_R0 + i] = regs->regs[i]; 189 gp[EF_R26] = 0; 190 gp[EF_R27] = 0; 191 gp[EF_LO] = regs->lo; 192 gp[EF_HI] = regs->hi; 193 gp[EF_CP0_EPC] = regs->cp0_epc; 194 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 195 gp[EF_CP0_STATUS] = regs->cp0_status; 196 gp[EF_CP0_CAUSE] = regs->cp0_cause; 197 #ifdef EF_UNUSED0 198 gp[EF_UNUSED0] = 0; 199 #endif 200 } 201 202 int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs) 203 { 204 elf_dump_regs(*regs, task_pt_regs(tsk)); 205 return 1; 206 } 207 208 int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr) 209 { 210 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 211 212 return 1; 213 } 214 215 /* 216 * Create a kernel thread 217 */ 218 static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) 219 { 220 do_exit(fn(arg)); 221 } 222 223 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 224 { 225 struct pt_regs regs; 226 227 memset(®s, 0, sizeof(regs)); 228 229 regs.regs[4] = (unsigned long) arg; 230 regs.regs[5] = (unsigned long) fn; 231 regs.cp0_epc = (unsigned long) kernel_thread_helper; 232 regs.cp0_status = read_c0_status(); 233 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 234 regs.cp0_status &= ~(ST0_KUP | ST0_IEC); 235 regs.cp0_status |= ST0_IEP; 236 #else 237 regs.cp0_status |= ST0_EXL; 238 #endif 239 240 /* Ok, create the new process.. */ 241 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 242 } 243 244 /* 245 * 246 */ 247 struct mips_frame_info { 248 void *func; 249 unsigned long func_size; 250 int frame_size; 251 int pc_offset; 252 }; 253 254 static inline int is_ra_save_ins(union mips_instruction *ip) 255 { 256 /* sw / sd $ra, offset($sp) */ 257 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 258 ip->i_format.rs == 29 && 259 ip->i_format.rt == 31; 260 } 261 262 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 263 { 264 if (ip->j_format.opcode == jal_op) 265 return 1; 266 if (ip->r_format.opcode != spec_op) 267 return 0; 268 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 269 } 270 271 static inline int is_sp_move_ins(union mips_instruction *ip) 272 { 273 /* addiu/daddiu sp,sp,-imm */ 274 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 275 return 0; 276 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 277 return 1; 278 return 0; 279 } 280 281 static int get_frame_info(struct mips_frame_info *info) 282 { 283 union mips_instruction *ip = info->func; 284 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 285 unsigned i; 286 287 info->pc_offset = -1; 288 info->frame_size = 0; 289 290 if (!ip) 291 goto err; 292 293 if (max_insns == 0) 294 max_insns = 128U; /* unknown function size */ 295 max_insns = min(128U, max_insns); 296 297 for (i = 0; i < max_insns; i++, ip++) { 298 299 if (is_jal_jalr_jr_ins(ip)) 300 break; 301 if (!info->frame_size) { 302 if (is_sp_move_ins(ip)) 303 info->frame_size = - ip->i_format.simmediate; 304 continue; 305 } 306 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 307 info->pc_offset = 308 ip->i_format.simmediate / sizeof(long); 309 break; 310 } 311 } 312 if (info->frame_size && info->pc_offset >= 0) /* nested */ 313 return 0; 314 if (info->pc_offset < 0) /* leaf */ 315 return 1; 316 /* prologue seems boggus... */ 317 err: 318 return -1; 319 } 320 321 static struct mips_frame_info schedule_mfi __read_mostly; 322 323 static int __init frame_info_init(void) 324 { 325 unsigned long size = 0; 326 #ifdef CONFIG_KALLSYMS 327 unsigned long ofs; 328 329 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 330 #endif 331 schedule_mfi.func = schedule; 332 schedule_mfi.func_size = size; 333 334 get_frame_info(&schedule_mfi); 335 336 /* 337 * Without schedule() frame info, result given by 338 * thread_saved_pc() and get_wchan() are not reliable. 339 */ 340 if (schedule_mfi.pc_offset < 0) 341 printk("Can't analyze schedule() prologue at %p\n", schedule); 342 343 return 0; 344 } 345 346 arch_initcall(frame_info_init); 347 348 /* 349 * Return saved PC of a blocked thread. 350 */ 351 unsigned long thread_saved_pc(struct task_struct *tsk) 352 { 353 struct thread_struct *t = &tsk->thread; 354 355 /* New born processes are a special case */ 356 if (t->reg31 == (unsigned long) ret_from_fork) 357 return t->reg31; 358 if (schedule_mfi.pc_offset < 0) 359 return 0; 360 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 361 } 362 363 364 #ifdef CONFIG_KALLSYMS 365 /* used by show_backtrace() */ 366 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 367 unsigned long pc, unsigned long *ra) 368 { 369 unsigned long stack_page; 370 struct mips_frame_info info; 371 unsigned long size, ofs; 372 int leaf; 373 extern void ret_from_irq(void); 374 extern void ret_from_exception(void); 375 376 stack_page = (unsigned long)task_stack_page(task); 377 if (!stack_page) 378 return 0; 379 380 /* 381 * If we reached the bottom of interrupt context, 382 * return saved pc in pt_regs. 383 */ 384 if (pc == (unsigned long)ret_from_irq || 385 pc == (unsigned long)ret_from_exception) { 386 struct pt_regs *regs; 387 if (*sp >= stack_page && 388 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 389 regs = (struct pt_regs *)*sp; 390 pc = regs->cp0_epc; 391 if (__kernel_text_address(pc)) { 392 *sp = regs->regs[29]; 393 *ra = regs->regs[31]; 394 return pc; 395 } 396 } 397 return 0; 398 } 399 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 400 return 0; 401 /* 402 * Return ra if an exception occured at the first instruction 403 */ 404 if (unlikely(ofs == 0)) { 405 pc = *ra; 406 *ra = 0; 407 return pc; 408 } 409 410 info.func = (void *)(pc - ofs); 411 info.func_size = ofs; /* analyze from start to ofs */ 412 leaf = get_frame_info(&info); 413 if (leaf < 0) 414 return 0; 415 416 if (*sp < stack_page || 417 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 418 return 0; 419 420 if (leaf) 421 /* 422 * For some extreme cases, get_frame_info() can 423 * consider wrongly a nested function as a leaf 424 * one. In that cases avoid to return always the 425 * same value. 426 */ 427 pc = pc != *ra ? *ra : 0; 428 else 429 pc = ((unsigned long *)(*sp))[info.pc_offset]; 430 431 *sp += info.frame_size; 432 *ra = 0; 433 return __kernel_text_address(pc) ? pc : 0; 434 } 435 #endif 436 437 /* 438 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 439 */ 440 unsigned long get_wchan(struct task_struct *task) 441 { 442 unsigned long pc = 0; 443 #ifdef CONFIG_KALLSYMS 444 unsigned long sp; 445 unsigned long ra = 0; 446 #endif 447 448 if (!task || task == current || task->state == TASK_RUNNING) 449 goto out; 450 if (!task_stack_page(task)) 451 goto out; 452 453 pc = thread_saved_pc(task); 454 455 #ifdef CONFIG_KALLSYMS 456 sp = task->thread.reg29 + schedule_mfi.frame_size; 457 458 while (in_sched_functions(pc)) 459 pc = unwind_stack(task, &sp, pc, &ra); 460 #endif 461 462 out: 463 return pc; 464 } 465 466 /* 467 * Don't forget that the stack pointer must be aligned on a 8 bytes 468 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 469 */ 470 unsigned long arch_align_stack(unsigned long sp) 471 { 472 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 473 sp -= get_random_int() & ~PAGE_MASK; 474 475 return sp & ALMASK; 476 } 477