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/mman.h> 21#include <linux/personality.h> 22#include <linux/sys.h> 23#include <linux/user.h> 24#include <linux/init.h> 25#include <linux/completion.h> 26#include <linux/kallsyms.h> 27#include <linux/random.h> 28 29#include <asm/asm.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 */ 50void __noreturn cpu_idle(void) 51{ 52 int cpu; 53 54 /* CPU is going idle. */ 55 cpu = smp_processor_id(); 56 57 /* endless idle loop with no priority at all */ 58 while (1) { 59 tick_nohz_stop_sched_tick(1); 60 while (!need_resched() && cpu_online(cpu)) { 61#ifdef CONFIG_MIPS_MT_SMTC 62 extern void smtc_idle_loop_hook(void); 63 64 smtc_idle_loop_hook(); 65#endif 66 67 if (cpu_wait) { 68 /* Don't trace irqs off for idle */ 69 stop_critical_timings(); 70 (*cpu_wait)(); 71 start_critical_timings(); 72 } 73 } 74#ifdef CONFIG_HOTPLUG_CPU 75 if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) && 76 (system_state == SYSTEM_RUNNING || 77 system_state == SYSTEM_BOOTING)) 78 play_dead(); 79#endif 80 tick_nohz_restart_sched_tick(); 81 preempt_enable_no_resched(); 82 schedule(); 83 preempt_disable(); 84 } 85} 86 87asmlinkage void ret_from_fork(void); 88 89void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 90{ 91 unsigned long status; 92 93 /* New thread loses kernel privileges. */ 94 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 95#ifdef CONFIG_64BIT 96 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 97#endif 98 status |= KU_USER; 99 regs->cp0_status = status; 100 clear_used_math(); 101 clear_fpu_owner(); 102 if (cpu_has_dsp) 103 __init_dsp(); 104 regs->cp0_epc = pc; 105 regs->regs[29] = sp; 106 current_thread_info()->addr_limit = USER_DS; 107} 108 109void exit_thread(void) 110{ 111} 112 113void flush_thread(void) 114{ 115} 116 117int copy_thread(unsigned long clone_flags, unsigned long usp, 118 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 119{ 120 struct thread_info *ti = task_thread_info(p); 121 struct pt_regs *childregs; 122 unsigned long childksp; 123 p->set_child_tid = p->clear_child_tid = NULL; 124 125 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 126 127 preempt_disable(); 128 129 if (is_fpu_owner()) 130 save_fp(p); 131 132 if (cpu_has_dsp) 133 save_dsp(p); 134 135 preempt_enable(); 136 137 /* set up new TSS. */ 138 childregs = (struct pt_regs *) childksp - 1; 139 /* Put the stack after the struct pt_regs. */ 140 childksp = (unsigned long) childregs; 141 *childregs = *regs; 142 childregs->regs[7] = 0; /* Clear error flag */ 143 144 childregs->regs[2] = 0; /* Child gets zero as return value */ 145 146 if (childregs->cp0_status & ST0_CU0) { 147 childregs->regs[28] = (unsigned long) ti; 148 childregs->regs[29] = childksp; 149 ti->addr_limit = KERNEL_DS; 150 } else { 151 childregs->regs[29] = usp; 152 ti->addr_limit = USER_DS; 153 } 154 p->thread.reg29 = (unsigned long) childregs; 155 p->thread.reg31 = (unsigned long) ret_from_fork; 156 157 /* 158 * New tasks lose permission to use the fpu. This accelerates context 159 * switching for most programs since they don't use the fpu. 160 */ 161 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 162 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 163 164#ifdef CONFIG_MIPS_MT_SMTC 165 /* 166 * SMTC restores TCStatus after Status, and the CU bits 167 * are aliased there. 168 */ 169 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 170#endif 171 clear_tsk_thread_flag(p, TIF_USEDFPU); 172 173#ifdef CONFIG_MIPS_MT_FPAFF 174 clear_tsk_thread_flag(p, TIF_FPUBOUND); 175#endif /* CONFIG_MIPS_MT_FPAFF */ 176 177 if (clone_flags & CLONE_SETTLS) 178 ti->tp_value = regs->regs[7]; 179 180 return 0; 181} 182 183/* Fill in the fpu structure for a core dump.. */ 184int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 185{ 186 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 187 188 return 1; 189} 190 191void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 192{ 193 int i; 194 195 for (i = 0; i < EF_R0; i++) 196 gp[i] = 0; 197 gp[EF_R0] = 0; 198 for (i = 1; i <= 31; i++) 199 gp[EF_R0 + i] = regs->regs[i]; 200 gp[EF_R26] = 0; 201 gp[EF_R27] = 0; 202 gp[EF_LO] = regs->lo; 203 gp[EF_HI] = regs->hi; 204 gp[EF_CP0_EPC] = regs->cp0_epc; 205 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 206 gp[EF_CP0_STATUS] = regs->cp0_status; 207 gp[EF_CP0_CAUSE] = regs->cp0_cause; 208#ifdef EF_UNUSED0 209 gp[EF_UNUSED0] = 0; 210#endif 211} 212 213int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 214{ 215 elf_dump_regs(*regs, task_pt_regs(tsk)); 216 return 1; 217} 218 219int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 220{ 221 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 222 223 return 1; 224} 225 226/* 227 * Create a kernel thread 228 */ 229static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) 230{ 231 do_exit(fn(arg)); 232} 233 234long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 235{ 236 struct pt_regs regs; 237 238 memset(®s, 0, sizeof(regs)); 239 240 regs.regs[4] = (unsigned long) arg; 241 regs.regs[5] = (unsigned long) fn; 242 regs.cp0_epc = (unsigned long) kernel_thread_helper; 243 regs.cp0_status = read_c0_status(); 244#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 245 regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 246 ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); 247#else 248 regs.cp0_status |= ST0_EXL; 249#endif 250 251 /* Ok, create the new process.. */ 252 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 253} 254 255/* 256 * 257 */ 258struct mips_frame_info { 259 void *func; 260 unsigned long func_size; 261 int frame_size; 262 int pc_offset; 263}; 264 265static inline int is_ra_save_ins(union mips_instruction *ip) 266{ 267 /* sw / sd $ra, offset($sp) */ 268 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 269 ip->i_format.rs == 29 && 270 ip->i_format.rt == 31; 271} 272 273static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 274{ 275 if (ip->j_format.opcode == jal_op) 276 return 1; 277 if (ip->r_format.opcode != spec_op) 278 return 0; 279 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 280} 281 282static inline int is_sp_move_ins(union mips_instruction *ip) 283{ 284 /* addiu/daddiu sp,sp,-imm */ 285 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 286 return 0; 287 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 288 return 1; 289 return 0; 290} 291 292static int get_frame_info(struct mips_frame_info *info) 293{ 294 union mips_instruction *ip = info->func; 295 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 296 unsigned i; 297 298 info->pc_offset = -1; 299 info->frame_size = 0; 300 301 if (!ip) 302 goto err; 303 304 if (max_insns == 0) 305 max_insns = 128U; /* unknown function size */ 306 max_insns = min(128U, max_insns); 307 308 for (i = 0; i < max_insns; i++, ip++) { 309 310 if (is_jal_jalr_jr_ins(ip)) 311 break; 312 if (!info->frame_size) { 313 if (is_sp_move_ins(ip)) 314 info->frame_size = - ip->i_format.simmediate; 315 continue; 316 } 317 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 318 info->pc_offset = 319 ip->i_format.simmediate / sizeof(long); 320 break; 321 } 322 } 323 if (info->frame_size && info->pc_offset >= 0) /* nested */ 324 return 0; 325 if (info->pc_offset < 0) /* leaf */ 326 return 1; 327 /* prologue seems boggus... */ 328err: 329 return -1; 330} 331 332static struct mips_frame_info schedule_mfi __read_mostly; 333 334static int __init frame_info_init(void) 335{ 336 unsigned long size = 0; 337#ifdef CONFIG_KALLSYMS 338 unsigned long ofs; 339 340 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 341#endif 342 schedule_mfi.func = schedule; 343 schedule_mfi.func_size = size; 344 345 get_frame_info(&schedule_mfi); 346 347 /* 348 * Without schedule() frame info, result given by 349 * thread_saved_pc() and get_wchan() are not reliable. 350 */ 351 if (schedule_mfi.pc_offset < 0) 352 printk("Can't analyze schedule() prologue at %p\n", schedule); 353 354 return 0; 355} 356 357arch_initcall(frame_info_init); 358 359/* 360 * Return saved PC of a blocked thread. 361 */ 362unsigned long thread_saved_pc(struct task_struct *tsk) 363{ 364 struct thread_struct *t = &tsk->thread; 365 366 /* New born processes are a special case */ 367 if (t->reg31 == (unsigned long) ret_from_fork) 368 return t->reg31; 369 if (schedule_mfi.pc_offset < 0) 370 return 0; 371 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 372} 373 374 375#ifdef CONFIG_KALLSYMS 376/* used by show_backtrace() */ 377unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 378 unsigned long pc, unsigned long *ra) 379{ 380 unsigned long stack_page; 381 struct mips_frame_info info; 382 unsigned long size, ofs; 383 int leaf; 384 extern void ret_from_irq(void); 385 extern void ret_from_exception(void); 386 387 stack_page = (unsigned long)task_stack_page(task); 388 if (!stack_page) 389 return 0; 390 391 /* 392 * If we reached the bottom of interrupt context, 393 * return saved pc in pt_regs. 394 */ 395 if (pc == (unsigned long)ret_from_irq || 396 pc == (unsigned long)ret_from_exception) { 397 struct pt_regs *regs; 398 if (*sp >= stack_page && 399 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 400 regs = (struct pt_regs *)*sp; 401 pc = regs->cp0_epc; 402 if (__kernel_text_address(pc)) { 403 *sp = regs->regs[29]; 404 *ra = regs->regs[31]; 405 return pc; 406 } 407 } 408 return 0; 409 } 410 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 411 return 0; 412 /* 413 * Return ra if an exception occured at the first instruction 414 */ 415 if (unlikely(ofs == 0)) { 416 pc = *ra; 417 *ra = 0; 418 return pc; 419 } 420 421 info.func = (void *)(pc - ofs); 422 info.func_size = ofs; /* analyze from start to ofs */ 423 leaf = get_frame_info(&info); 424 if (leaf < 0) 425 return 0; 426 427 if (*sp < stack_page || 428 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 429 return 0; 430 431 if (leaf) 432 /* 433 * For some extreme cases, get_frame_info() can 434 * consider wrongly a nested function as a leaf 435 * one. In that cases avoid to return always the 436 * same value. 437 */ 438 pc = pc != *ra ? *ra : 0; 439 else 440 pc = ((unsigned long *)(*sp))[info.pc_offset]; 441 442 *sp += info.frame_size; 443 *ra = 0; 444 return __kernel_text_address(pc) ? pc : 0; 445} 446#endif 447 448/* 449 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 450 */ 451unsigned long get_wchan(struct task_struct *task) 452{ 453 unsigned long pc = 0; 454#ifdef CONFIG_KALLSYMS 455 unsigned long sp; 456 unsigned long ra = 0; 457#endif 458 459 if (!task || task == current || task->state == TASK_RUNNING) 460 goto out; 461 if (!task_stack_page(task)) 462 goto out; 463 464 pc = thread_saved_pc(task); 465 466#ifdef CONFIG_KALLSYMS 467 sp = task->thread.reg29 + schedule_mfi.frame_size; 468 469 while (in_sched_functions(pc)) 470 pc = unwind_stack(task, &sp, pc, &ra); 471#endif 472 473out: 474 return pc; 475} 476 477/* 478 * Don't forget that the stack pointer must be aligned on a 8 bytes 479 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 480 */ 481unsigned long arch_align_stack(unsigned long sp) 482{ 483 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 484 sp -= get_random_int() & ~PAGE_MASK; 485 486 return sp & ALMASK; 487} 488