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/bootinfo.h> 30 #include <asm/cpu.h> 31 #include <asm/dsp.h> 32 #include <asm/fpu.h> 33 #include <asm/pgtable.h> 34 #include <asm/system.h> 35 #include <asm/mipsregs.h> 36 #include <asm/processor.h> 37 #include <asm/uaccess.h> 38 #include <asm/io.h> 39 #include <asm/elf.h> 40 #include <asm/isadep.h> 41 #include <asm/inst.h> 42 #include <asm/stacktrace.h> 43 44 /* 45 * The idle thread. There's no useful work to be done, so just try to conserve 46 * power and have a low exit latency (ie sit in a loop waiting for somebody to 47 * say that they'd like to reschedule) 48 */ 49 ATTRIB_NORET void cpu_idle(void) 50 { 51 /* endless idle loop with no priority at all */ 52 while (1) { 53 while (!need_resched()) { 54 #ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG 55 extern void smtc_idle_loop_hook(void); 56 57 smtc_idle_loop_hook(); 58 #endif 59 if (cpu_wait) 60 (*cpu_wait)(); 61 } 62 preempt_enable_no_resched(); 63 schedule(); 64 preempt_disable(); 65 } 66 } 67 68 asmlinkage void ret_from_fork(void); 69 70 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 71 { 72 unsigned long status; 73 74 /* New thread loses kernel privileges. */ 75 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK); 76 #ifdef CONFIG_64BIT 77 status &= ~ST0_FR; 78 status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR; 79 #endif 80 status |= KU_USER; 81 regs->cp0_status = status; 82 clear_used_math(); 83 clear_fpu_owner(); 84 if (cpu_has_dsp) 85 __init_dsp(); 86 regs->cp0_epc = pc; 87 regs->regs[29] = sp; 88 current_thread_info()->addr_limit = USER_DS; 89 } 90 91 void exit_thread(void) 92 { 93 } 94 95 void flush_thread(void) 96 { 97 } 98 99 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 100 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 101 { 102 struct thread_info *ti = task_thread_info(p); 103 struct pt_regs *childregs; 104 long childksp; 105 p->set_child_tid = p->clear_child_tid = NULL; 106 107 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 108 109 preempt_disable(); 110 111 if (is_fpu_owner()) 112 save_fp(p); 113 114 if (cpu_has_dsp) 115 save_dsp(p); 116 117 preempt_enable(); 118 119 /* set up new TSS. */ 120 childregs = (struct pt_regs *) childksp - 1; 121 *childregs = *regs; 122 childregs->regs[7] = 0; /* Clear error flag */ 123 124 #if defined(CONFIG_BINFMT_IRIX) 125 if (current->personality != PER_LINUX) { 126 /* Under IRIX things are a little different. */ 127 childregs->regs[3] = 1; 128 regs->regs[3] = 0; 129 } 130 #endif 131 childregs->regs[2] = 0; /* Child gets zero as return value */ 132 regs->regs[2] = p->pid; 133 134 if (childregs->cp0_status & ST0_CU0) { 135 childregs->regs[28] = (unsigned long) ti; 136 childregs->regs[29] = childksp; 137 ti->addr_limit = KERNEL_DS; 138 } else { 139 childregs->regs[29] = usp; 140 ti->addr_limit = USER_DS; 141 } 142 p->thread.reg29 = (unsigned long) childregs; 143 p->thread.reg31 = (unsigned long) ret_from_fork; 144 145 /* 146 * New tasks lose permission to use the fpu. This accelerates context 147 * switching for most programs since they don't use the fpu. 148 */ 149 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 150 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 151 clear_tsk_thread_flag(p, TIF_USEDFPU); 152 153 #ifdef CONFIG_MIPS_MT_FPAFF 154 /* 155 * FPU affinity support is cleaner if we track the 156 * user-visible CPU affinity from the very beginning. 157 * The generic cpus_allowed mask will already have 158 * been copied from the parent before copy_thread 159 * is invoked. 160 */ 161 p->thread.user_cpus_allowed = p->cpus_allowed; 162 #endif /* CONFIG_MIPS_MT_FPAFF */ 163 164 if (clone_flags & CLONE_SETTLS) 165 ti->tp_value = regs->regs[7]; 166 167 return 0; 168 } 169 170 /* Fill in the fpu structure for a core dump.. */ 171 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 172 { 173 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 174 175 return 1; 176 } 177 178 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 179 { 180 int i; 181 182 for (i = 0; i < EF_R0; i++) 183 gp[i] = 0; 184 gp[EF_R0] = 0; 185 for (i = 1; i <= 31; i++) 186 gp[EF_R0 + i] = regs->regs[i]; 187 gp[EF_R26] = 0; 188 gp[EF_R27] = 0; 189 gp[EF_LO] = regs->lo; 190 gp[EF_HI] = regs->hi; 191 gp[EF_CP0_EPC] = regs->cp0_epc; 192 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 193 gp[EF_CP0_STATUS] = regs->cp0_status; 194 gp[EF_CP0_CAUSE] = regs->cp0_cause; 195 #ifdef EF_UNUSED0 196 gp[EF_UNUSED0] = 0; 197 #endif 198 } 199 200 int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs) 201 { 202 elf_dump_regs(*regs, task_pt_regs(tsk)); 203 return 1; 204 } 205 206 int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr) 207 { 208 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 209 210 return 1; 211 } 212 213 /* 214 * Create a kernel thread 215 */ 216 static ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *)) 217 { 218 do_exit(fn(arg)); 219 } 220 221 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 222 { 223 struct pt_regs regs; 224 225 memset(®s, 0, sizeof(regs)); 226 227 regs.regs[4] = (unsigned long) arg; 228 regs.regs[5] = (unsigned long) fn; 229 regs.cp0_epc = (unsigned long) kernel_thread_helper; 230 regs.cp0_status = read_c0_status(); 231 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 232 regs.cp0_status &= ~(ST0_KUP | ST0_IEC); 233 regs.cp0_status |= ST0_IEP; 234 #else 235 regs.cp0_status |= ST0_EXL; 236 #endif 237 238 /* Ok, create the new process.. */ 239 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 240 } 241 242 /* 243 * 244 */ 245 struct mips_frame_info { 246 void *func; 247 unsigned long func_size; 248 int frame_size; 249 int pc_offset; 250 }; 251 252 static inline int is_ra_save_ins(union mips_instruction *ip) 253 { 254 /* sw / sd $ra, offset($sp) */ 255 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 256 ip->i_format.rs == 29 && 257 ip->i_format.rt == 31; 258 } 259 260 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 261 { 262 if (ip->j_format.opcode == jal_op) 263 return 1; 264 if (ip->r_format.opcode != spec_op) 265 return 0; 266 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 267 } 268 269 static inline int is_sp_move_ins(union mips_instruction *ip) 270 { 271 /* addiu/daddiu sp,sp,-imm */ 272 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 273 return 0; 274 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 275 return 1; 276 return 0; 277 } 278 279 static int get_frame_info(struct mips_frame_info *info) 280 { 281 union mips_instruction *ip = info->func; 282 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 283 unsigned i; 284 285 info->pc_offset = -1; 286 info->frame_size = 0; 287 288 if (!ip) 289 goto err; 290 291 if (max_insns == 0) 292 max_insns = 128U; /* unknown function size */ 293 max_insns = min(128U, max_insns); 294 295 for (i = 0; i < max_insns; i++, ip++) { 296 297 if (is_jal_jalr_jr_ins(ip)) 298 break; 299 if (!info->frame_size) { 300 if (is_sp_move_ins(ip)) 301 info->frame_size = - ip->i_format.simmediate; 302 continue; 303 } 304 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 305 info->pc_offset = 306 ip->i_format.simmediate / sizeof(long); 307 break; 308 } 309 } 310 if (info->frame_size && info->pc_offset >= 0) /* nested */ 311 return 0; 312 if (info->pc_offset < 0) /* leaf */ 313 return 1; 314 /* prologue seems boggus... */ 315 err: 316 return -1; 317 } 318 319 static struct mips_frame_info schedule_mfi __read_mostly; 320 321 static int __init frame_info_init(void) 322 { 323 unsigned long size = 0; 324 #ifdef CONFIG_KALLSYMS 325 unsigned long ofs; 326 327 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 328 #endif 329 schedule_mfi.func = schedule; 330 schedule_mfi.func_size = size; 331 332 get_frame_info(&schedule_mfi); 333 334 /* 335 * Without schedule() frame info, result given by 336 * thread_saved_pc() and get_wchan() are not reliable. 337 */ 338 if (schedule_mfi.pc_offset < 0) 339 printk("Can't analyze schedule() prologue at %p\n", schedule); 340 341 return 0; 342 } 343 344 arch_initcall(frame_info_init); 345 346 /* 347 * Return saved PC of a blocked thread. 348 */ 349 unsigned long thread_saved_pc(struct task_struct *tsk) 350 { 351 struct thread_struct *t = &tsk->thread; 352 353 /* New born processes are a special case */ 354 if (t->reg31 == (unsigned long) ret_from_fork) 355 return t->reg31; 356 if (schedule_mfi.pc_offset < 0) 357 return 0; 358 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 359 } 360 361 362 #ifdef CONFIG_KALLSYMS 363 /* used by show_backtrace() */ 364 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 365 unsigned long pc, unsigned long *ra) 366 { 367 unsigned long stack_page; 368 struct mips_frame_info info; 369 unsigned long size, ofs; 370 int leaf; 371 extern void ret_from_irq(void); 372 extern void ret_from_exception(void); 373 374 stack_page = (unsigned long)task_stack_page(task); 375 if (!stack_page) 376 return 0; 377 378 /* 379 * If we reached the bottom of interrupt context, 380 * return saved pc in pt_regs. 381 */ 382 if (pc == (unsigned long)ret_from_irq || 383 pc == (unsigned long)ret_from_exception) { 384 struct pt_regs *regs; 385 if (*sp >= stack_page && 386 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 387 regs = (struct pt_regs *)*sp; 388 pc = regs->cp0_epc; 389 if (__kernel_text_address(pc)) { 390 *sp = regs->regs[29]; 391 *ra = regs->regs[31]; 392 return pc; 393 } 394 } 395 return 0; 396 } 397 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 398 return 0; 399 /* 400 * Return ra if an exception occured at the first instruction 401 */ 402 if (unlikely(ofs == 0)) { 403 pc = *ra; 404 *ra = 0; 405 return pc; 406 } 407 408 info.func = (void *)(pc - ofs); 409 info.func_size = ofs; /* analyze from start to ofs */ 410 leaf = get_frame_info(&info); 411 if (leaf < 0) 412 return 0; 413 414 if (*sp < stack_page || 415 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 416 return 0; 417 418 if (leaf) 419 /* 420 * For some extreme cases, get_frame_info() can 421 * consider wrongly a nested function as a leaf 422 * one. In that cases avoid to return always the 423 * same value. 424 */ 425 pc = pc != *ra ? *ra : 0; 426 else 427 pc = ((unsigned long *)(*sp))[info.pc_offset]; 428 429 *sp += info.frame_size; 430 *ra = 0; 431 return __kernel_text_address(pc) ? pc : 0; 432 } 433 #endif 434 435 /* 436 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 437 */ 438 unsigned long get_wchan(struct task_struct *task) 439 { 440 unsigned long pc = 0; 441 #ifdef CONFIG_KALLSYMS 442 unsigned long sp; 443 unsigned long ra = 0; 444 #endif 445 446 if (!task || task == current || task->state == TASK_RUNNING) 447 goto out; 448 if (!task_stack_page(task)) 449 goto out; 450 451 pc = thread_saved_pc(task); 452 453 #ifdef CONFIG_KALLSYMS 454 sp = task->thread.reg29 + schedule_mfi.frame_size; 455 456 while (in_sched_functions(pc)) 457 pc = unwind_stack(task, &sp, pc, &ra); 458 #endif 459 460 out: 461 return pc; 462 } 463