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/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/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 tick_nohz_stop_sched_tick(1); 56 while (!need_resched()) { 57 #ifdef CONFIG_MIPS_MT_SMTC 58 extern void smtc_idle_loop_hook(void); 59 60 smtc_idle_loop_hook(); 61 #endif 62 if (cpu_wait) 63 (*cpu_wait)(); 64 } 65 tick_nohz_restart_sched_tick(); 66 preempt_enable_no_resched(); 67 schedule(); 68 preempt_disable(); 69 } 70 } 71 72 asmlinkage void ret_from_fork(void); 73 74 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 75 { 76 unsigned long status; 77 78 /* New thread loses kernel privileges. */ 79 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 80 #ifdef CONFIG_64BIT 81 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 82 #endif 83 status |= KU_USER; 84 regs->cp0_status = status; 85 clear_used_math(); 86 clear_fpu_owner(); 87 if (cpu_has_dsp) 88 __init_dsp(); 89 regs->cp0_epc = pc; 90 regs->regs[29] = sp; 91 current_thread_info()->addr_limit = USER_DS; 92 } 93 94 void exit_thread(void) 95 { 96 } 97 98 void flush_thread(void) 99 { 100 } 101 102 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 103 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 104 { 105 struct thread_info *ti = task_thread_info(p); 106 struct pt_regs *childregs; 107 long childksp; 108 p->set_child_tid = p->clear_child_tid = NULL; 109 110 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 111 112 preempt_disable(); 113 114 if (is_fpu_owner()) 115 save_fp(p); 116 117 if (cpu_has_dsp) 118 save_dsp(p); 119 120 preempt_enable(); 121 122 /* set up new TSS. */ 123 childregs = (struct pt_regs *) childksp - 1; 124 *childregs = *regs; 125 childregs->regs[7] = 0; /* Clear error flag */ 126 127 childregs->regs[2] = 0; /* Child gets zero as return value */ 128 regs->regs[2] = p->pid; 129 130 if (childregs->cp0_status & ST0_CU0) { 131 childregs->regs[28] = (unsigned long) ti; 132 childregs->regs[29] = childksp; 133 ti->addr_limit = KERNEL_DS; 134 } else { 135 childregs->regs[29] = usp; 136 ti->addr_limit = USER_DS; 137 } 138 p->thread.reg29 = (unsigned long) childregs; 139 p->thread.reg31 = (unsigned long) ret_from_fork; 140 141 /* 142 * New tasks lose permission to use the fpu. This accelerates context 143 * switching for most programs since they don't use the fpu. 144 */ 145 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 146 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 147 148 #ifdef CONFIG_MIPS_MT_SMTC 149 /* 150 * SMTC restores TCStatus after Status, and the CU bits 151 * are aliased there. 152 */ 153 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 154 #endif 155 clear_tsk_thread_flag(p, TIF_USEDFPU); 156 157 #ifdef CONFIG_MIPS_MT_FPAFF 158 clear_tsk_thread_flag(p, TIF_FPUBOUND); 159 #endif /* CONFIG_MIPS_MT_FPAFF */ 160 161 if (clone_flags & CLONE_SETTLS) 162 ti->tp_value = regs->regs[7]; 163 164 return 0; 165 } 166 167 /* Fill in the fpu structure for a core dump.. */ 168 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 169 { 170 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 171 172 return 1; 173 } 174 175 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 176 { 177 int i; 178 179 for (i = 0; i < EF_R0; i++) 180 gp[i] = 0; 181 gp[EF_R0] = 0; 182 for (i = 1; i <= 31; i++) 183 gp[EF_R0 + i] = regs->regs[i]; 184 gp[EF_R26] = 0; 185 gp[EF_R27] = 0; 186 gp[EF_LO] = regs->lo; 187 gp[EF_HI] = regs->hi; 188 gp[EF_CP0_EPC] = regs->cp0_epc; 189 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 190 gp[EF_CP0_STATUS] = regs->cp0_status; 191 gp[EF_CP0_CAUSE] = regs->cp0_cause; 192 #ifdef EF_UNUSED0 193 gp[EF_UNUSED0] = 0; 194 #endif 195 } 196 197 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 198 { 199 elf_dump_regs(*regs, task_pt_regs(tsk)); 200 return 1; 201 } 202 203 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 204 { 205 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 206 207 return 1; 208 } 209 210 /* 211 * Create a kernel thread 212 */ 213 static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) 214 { 215 do_exit(fn(arg)); 216 } 217 218 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 219 { 220 struct pt_regs regs; 221 222 memset(®s, 0, sizeof(regs)); 223 224 regs.regs[4] = (unsigned long) arg; 225 regs.regs[5] = (unsigned long) fn; 226 regs.cp0_epc = (unsigned long) kernel_thread_helper; 227 regs.cp0_status = read_c0_status(); 228 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 229 regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 230 ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); 231 #else 232 regs.cp0_status |= ST0_EXL; 233 #endif 234 235 /* Ok, create the new process.. */ 236 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 237 } 238 239 /* 240 * 241 */ 242 struct mips_frame_info { 243 void *func; 244 unsigned long func_size; 245 int frame_size; 246 int pc_offset; 247 }; 248 249 static inline int is_ra_save_ins(union mips_instruction *ip) 250 { 251 /* sw / sd $ra, offset($sp) */ 252 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 253 ip->i_format.rs == 29 && 254 ip->i_format.rt == 31; 255 } 256 257 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 258 { 259 if (ip->j_format.opcode == jal_op) 260 return 1; 261 if (ip->r_format.opcode != spec_op) 262 return 0; 263 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 264 } 265 266 static inline int is_sp_move_ins(union mips_instruction *ip) 267 { 268 /* addiu/daddiu sp,sp,-imm */ 269 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 270 return 0; 271 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 272 return 1; 273 return 0; 274 } 275 276 static int get_frame_info(struct mips_frame_info *info) 277 { 278 union mips_instruction *ip = info->func; 279 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 280 unsigned i; 281 282 info->pc_offset = -1; 283 info->frame_size = 0; 284 285 if (!ip) 286 goto err; 287 288 if (max_insns == 0) 289 max_insns = 128U; /* unknown function size */ 290 max_insns = min(128U, max_insns); 291 292 for (i = 0; i < max_insns; i++, ip++) { 293 294 if (is_jal_jalr_jr_ins(ip)) 295 break; 296 if (!info->frame_size) { 297 if (is_sp_move_ins(ip)) 298 info->frame_size = - ip->i_format.simmediate; 299 continue; 300 } 301 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 302 info->pc_offset = 303 ip->i_format.simmediate / sizeof(long); 304 break; 305 } 306 } 307 if (info->frame_size && info->pc_offset >= 0) /* nested */ 308 return 0; 309 if (info->pc_offset < 0) /* leaf */ 310 return 1; 311 /* prologue seems boggus... */ 312 err: 313 return -1; 314 } 315 316 static struct mips_frame_info schedule_mfi __read_mostly; 317 318 static int __init frame_info_init(void) 319 { 320 unsigned long size = 0; 321 #ifdef CONFIG_KALLSYMS 322 unsigned long ofs; 323 324 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 325 #endif 326 schedule_mfi.func = schedule; 327 schedule_mfi.func_size = size; 328 329 get_frame_info(&schedule_mfi); 330 331 /* 332 * Without schedule() frame info, result given by 333 * thread_saved_pc() and get_wchan() are not reliable. 334 */ 335 if (schedule_mfi.pc_offset < 0) 336 printk("Can't analyze schedule() prologue at %p\n", schedule); 337 338 return 0; 339 } 340 341 arch_initcall(frame_info_init); 342 343 /* 344 * Return saved PC of a blocked thread. 345 */ 346 unsigned long thread_saved_pc(struct task_struct *tsk) 347 { 348 struct thread_struct *t = &tsk->thread; 349 350 /* New born processes are a special case */ 351 if (t->reg31 == (unsigned long) ret_from_fork) 352 return t->reg31; 353 if (schedule_mfi.pc_offset < 0) 354 return 0; 355 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 356 } 357 358 359 #ifdef CONFIG_KALLSYMS 360 /* used by show_backtrace() */ 361 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 362 unsigned long pc, unsigned long *ra) 363 { 364 unsigned long stack_page; 365 struct mips_frame_info info; 366 unsigned long size, ofs; 367 int leaf; 368 extern void ret_from_irq(void); 369 extern void ret_from_exception(void); 370 371 stack_page = (unsigned long)task_stack_page(task); 372 if (!stack_page) 373 return 0; 374 375 /* 376 * If we reached the bottom of interrupt context, 377 * return saved pc in pt_regs. 378 */ 379 if (pc == (unsigned long)ret_from_irq || 380 pc == (unsigned long)ret_from_exception) { 381 struct pt_regs *regs; 382 if (*sp >= stack_page && 383 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 384 regs = (struct pt_regs *)*sp; 385 pc = regs->cp0_epc; 386 if (__kernel_text_address(pc)) { 387 *sp = regs->regs[29]; 388 *ra = regs->regs[31]; 389 return pc; 390 } 391 } 392 return 0; 393 } 394 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 395 return 0; 396 /* 397 * Return ra if an exception occured at the first instruction 398 */ 399 if (unlikely(ofs == 0)) { 400 pc = *ra; 401 *ra = 0; 402 return pc; 403 } 404 405 info.func = (void *)(pc - ofs); 406 info.func_size = ofs; /* analyze from start to ofs */ 407 leaf = get_frame_info(&info); 408 if (leaf < 0) 409 return 0; 410 411 if (*sp < stack_page || 412 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 413 return 0; 414 415 if (leaf) 416 /* 417 * For some extreme cases, get_frame_info() can 418 * consider wrongly a nested function as a leaf 419 * one. In that cases avoid to return always the 420 * same value. 421 */ 422 pc = pc != *ra ? *ra : 0; 423 else 424 pc = ((unsigned long *)(*sp))[info.pc_offset]; 425 426 *sp += info.frame_size; 427 *ra = 0; 428 return __kernel_text_address(pc) ? pc : 0; 429 } 430 #endif 431 432 /* 433 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 434 */ 435 unsigned long get_wchan(struct task_struct *task) 436 { 437 unsigned long pc = 0; 438 #ifdef CONFIG_KALLSYMS 439 unsigned long sp; 440 unsigned long ra = 0; 441 #endif 442 443 if (!task || task == current || task->state == TASK_RUNNING) 444 goto out; 445 if (!task_stack_page(task)) 446 goto out; 447 448 pc = thread_saved_pc(task); 449 450 #ifdef CONFIG_KALLSYMS 451 sp = task->thread.reg29 + schedule_mfi.frame_size; 452 453 while (in_sched_functions(pc)) 454 pc = unwind_stack(task, &sp, pc, &ra); 455 #endif 456 457 out: 458 return pc; 459 } 460 461 /* 462 * Don't forget that the stack pointer must be aligned on a 8 bytes 463 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 464 */ 465 unsigned long arch_align_stack(unsigned long sp) 466 { 467 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 468 sp -= get_random_int() & ~PAGE_MASK; 469 470 return sp & ALMASK; 471 } 472