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/sched.h> 13 #include <linux/tick.h> 14 #include <linux/kernel.h> 15 #include <linux/mm.h> 16 #include <linux/stddef.h> 17 #include <linux/unistd.h> 18 #include <linux/export.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/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 #ifdef CONFIG_HOTPLUG_CPU 45 void arch_cpu_idle_dead(void) 46 { 47 /* What the heck is this check doing ? */ 48 if (!cpu_isset(smp_processor_id(), cpu_callin_map)) 49 play_dead(); 50 } 51 #endif 52 53 void arch_cpu_idle(void) 54 { 55 #ifdef CONFIG_MIPS_MT_SMTC 56 extern void smtc_idle_loop_hook(void); 57 58 smtc_idle_loop_hook(); 59 #endif 60 if (cpu_wait) 61 (*cpu_wait)(); 62 else 63 local_irq_enable(); 64 } 65 66 asmlinkage void ret_from_fork(void); 67 asmlinkage void ret_from_kernel_thread(void); 68 69 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 70 { 71 unsigned long status; 72 73 /* New thread loses kernel privileges. */ 74 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 75 #ifdef CONFIG_64BIT 76 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 77 #endif 78 status |= KU_USER; 79 regs->cp0_status = status; 80 clear_used_math(); 81 clear_fpu_owner(); 82 if (cpu_has_dsp) 83 __init_dsp(); 84 regs->cp0_epc = pc; 85 regs->regs[29] = sp; 86 } 87 88 void exit_thread(void) 89 { 90 } 91 92 void flush_thread(void) 93 { 94 } 95 96 int copy_thread(unsigned long clone_flags, unsigned long usp, 97 unsigned long arg, struct task_struct *p) 98 { 99 struct thread_info *ti = task_thread_info(p); 100 struct pt_regs *childregs, *regs = current_pt_regs(); 101 unsigned long childksp; 102 p->set_child_tid = p->clear_child_tid = NULL; 103 104 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 105 106 preempt_disable(); 107 108 if (is_fpu_owner()) 109 save_fp(p); 110 111 if (cpu_has_dsp) 112 save_dsp(p); 113 114 preempt_enable(); 115 116 /* set up new TSS. */ 117 childregs = (struct pt_regs *) childksp - 1; 118 /* Put the stack after the struct pt_regs. */ 119 childksp = (unsigned long) childregs; 120 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 121 if (unlikely(p->flags & PF_KTHREAD)) { 122 unsigned long status = p->thread.cp0_status; 123 memset(childregs, 0, sizeof(struct pt_regs)); 124 ti->addr_limit = KERNEL_DS; 125 p->thread.reg16 = usp; /* fn */ 126 p->thread.reg17 = arg; 127 p->thread.reg29 = childksp; 128 p->thread.reg31 = (unsigned long) ret_from_kernel_thread; 129 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 130 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 131 ((status & (ST0_KUC | ST0_IEC)) << 2); 132 #else 133 status |= ST0_EXL; 134 #endif 135 childregs->cp0_status = status; 136 return 0; 137 } 138 *childregs = *regs; 139 childregs->regs[7] = 0; /* Clear error flag */ 140 childregs->regs[2] = 0; /* Child gets zero as return value */ 141 if (usp) 142 childregs->regs[29] = usp; 143 ti->addr_limit = USER_DS; 144 145 p->thread.reg29 = (unsigned long) childregs; 146 p->thread.reg31 = (unsigned long) ret_from_fork; 147 148 /* 149 * New tasks lose permission to use the fpu. This accelerates context 150 * switching for most programs since they don't use the fpu. 151 */ 152 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 153 154 #ifdef CONFIG_MIPS_MT_SMTC 155 /* 156 * SMTC restores TCStatus after Status, and the CU bits 157 * are aliased there. 158 */ 159 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 160 #endif 161 clear_tsk_thread_flag(p, TIF_USEDFPU); 162 163 #ifdef CONFIG_MIPS_MT_FPAFF 164 clear_tsk_thread_flag(p, TIF_FPUBOUND); 165 #endif /* CONFIG_MIPS_MT_FPAFF */ 166 167 if (clone_flags & CLONE_SETTLS) 168 ti->tp_value = regs->regs[7]; 169 170 return 0; 171 } 172 173 /* Fill in the fpu structure for a core dump.. */ 174 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 175 { 176 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 177 178 return 1; 179 } 180 181 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 182 { 183 int i; 184 185 for (i = 0; i < EF_R0; i++) 186 gp[i] = 0; 187 gp[EF_R0] = 0; 188 for (i = 1; i <= 31; i++) 189 gp[EF_R0 + i] = regs->regs[i]; 190 gp[EF_R26] = 0; 191 gp[EF_R27] = 0; 192 gp[EF_LO] = regs->lo; 193 gp[EF_HI] = regs->hi; 194 gp[EF_CP0_EPC] = regs->cp0_epc; 195 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 196 gp[EF_CP0_STATUS] = regs->cp0_status; 197 gp[EF_CP0_CAUSE] = regs->cp0_cause; 198 #ifdef EF_UNUSED0 199 gp[EF_UNUSED0] = 0; 200 #endif 201 } 202 203 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 204 { 205 elf_dump_regs(*regs, task_pt_regs(tsk)); 206 return 1; 207 } 208 209 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 210 { 211 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 212 213 return 1; 214 } 215 216 /* 217 * 218 */ 219 struct mips_frame_info { 220 void *func; 221 unsigned long func_size; 222 int frame_size; 223 int pc_offset; 224 }; 225 226 static inline int is_ra_save_ins(union mips_instruction *ip) 227 { 228 /* sw / sd $ra, offset($sp) */ 229 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 230 ip->i_format.rs == 29 && 231 ip->i_format.rt == 31; 232 } 233 234 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) 235 { 236 if (ip->j_format.opcode == jal_op) 237 return 1; 238 if (ip->r_format.opcode != spec_op) 239 return 0; 240 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 241 } 242 243 static inline int is_sp_move_ins(union mips_instruction *ip) 244 { 245 /* addiu/daddiu sp,sp,-imm */ 246 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 247 return 0; 248 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 249 return 1; 250 return 0; 251 } 252 253 static int get_frame_info(struct mips_frame_info *info) 254 { 255 union mips_instruction *ip = info->func; 256 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 257 unsigned i; 258 259 info->pc_offset = -1; 260 info->frame_size = 0; 261 262 if (!ip) 263 goto err; 264 265 if (max_insns == 0) 266 max_insns = 128U; /* unknown function size */ 267 max_insns = min(128U, max_insns); 268 269 for (i = 0; i < max_insns; i++, ip++) { 270 271 if (is_jal_jalr_jr_ins(ip)) 272 break; 273 if (!info->frame_size) { 274 if (is_sp_move_ins(ip)) 275 info->frame_size = - ip->i_format.simmediate; 276 continue; 277 } 278 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 279 info->pc_offset = 280 ip->i_format.simmediate / sizeof(long); 281 break; 282 } 283 } 284 if (info->frame_size && info->pc_offset >= 0) /* nested */ 285 return 0; 286 if (info->pc_offset < 0) /* leaf */ 287 return 1; 288 /* prologue seems boggus... */ 289 err: 290 return -1; 291 } 292 293 static struct mips_frame_info schedule_mfi __read_mostly; 294 295 static int __init frame_info_init(void) 296 { 297 unsigned long size = 0; 298 #ifdef CONFIG_KALLSYMS 299 unsigned long ofs; 300 301 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); 302 #endif 303 schedule_mfi.func = schedule; 304 schedule_mfi.func_size = size; 305 306 get_frame_info(&schedule_mfi); 307 308 /* 309 * Without schedule() frame info, result given by 310 * thread_saved_pc() and get_wchan() are not reliable. 311 */ 312 if (schedule_mfi.pc_offset < 0) 313 printk("Can't analyze schedule() prologue at %p\n", schedule); 314 315 return 0; 316 } 317 318 arch_initcall(frame_info_init); 319 320 /* 321 * Return saved PC of a blocked thread. 322 */ 323 unsigned long thread_saved_pc(struct task_struct *tsk) 324 { 325 struct thread_struct *t = &tsk->thread; 326 327 /* New born processes are a special case */ 328 if (t->reg31 == (unsigned long) ret_from_fork) 329 return t->reg31; 330 if (schedule_mfi.pc_offset < 0) 331 return 0; 332 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 333 } 334 335 336 #ifdef CONFIG_KALLSYMS 337 /* generic stack unwinding function */ 338 unsigned long notrace unwind_stack_by_address(unsigned long stack_page, 339 unsigned long *sp, 340 unsigned long pc, 341 unsigned long *ra) 342 { 343 struct mips_frame_info info; 344 unsigned long size, ofs; 345 int leaf; 346 extern void ret_from_irq(void); 347 extern void ret_from_exception(void); 348 349 if (!stack_page) 350 return 0; 351 352 /* 353 * If we reached the bottom of interrupt context, 354 * return saved pc in pt_regs. 355 */ 356 if (pc == (unsigned long)ret_from_irq || 357 pc == (unsigned long)ret_from_exception) { 358 struct pt_regs *regs; 359 if (*sp >= stack_page && 360 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 361 regs = (struct pt_regs *)*sp; 362 pc = regs->cp0_epc; 363 if (__kernel_text_address(pc)) { 364 *sp = regs->regs[29]; 365 *ra = regs->regs[31]; 366 return pc; 367 } 368 } 369 return 0; 370 } 371 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 372 return 0; 373 /* 374 * Return ra if an exception occurred at the first instruction 375 */ 376 if (unlikely(ofs == 0)) { 377 pc = *ra; 378 *ra = 0; 379 return pc; 380 } 381 382 info.func = (void *)(pc - ofs); 383 info.func_size = ofs; /* analyze from start to ofs */ 384 leaf = get_frame_info(&info); 385 if (leaf < 0) 386 return 0; 387 388 if (*sp < stack_page || 389 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 390 return 0; 391 392 if (leaf) 393 /* 394 * For some extreme cases, get_frame_info() can 395 * consider wrongly a nested function as a leaf 396 * one. In that cases avoid to return always the 397 * same value. 398 */ 399 pc = pc != *ra ? *ra : 0; 400 else 401 pc = ((unsigned long *)(*sp))[info.pc_offset]; 402 403 *sp += info.frame_size; 404 *ra = 0; 405 return __kernel_text_address(pc) ? pc : 0; 406 } 407 EXPORT_SYMBOL(unwind_stack_by_address); 408 409 /* used by show_backtrace() */ 410 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 411 unsigned long pc, unsigned long *ra) 412 { 413 unsigned long stack_page = (unsigned long)task_stack_page(task); 414 return unwind_stack_by_address(stack_page, sp, pc, ra); 415 } 416 #endif 417 418 /* 419 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 420 */ 421 unsigned long get_wchan(struct task_struct *task) 422 { 423 unsigned long pc = 0; 424 #ifdef CONFIG_KALLSYMS 425 unsigned long sp; 426 unsigned long ra = 0; 427 #endif 428 429 if (!task || task == current || task->state == TASK_RUNNING) 430 goto out; 431 if (!task_stack_page(task)) 432 goto out; 433 434 pc = thread_saved_pc(task); 435 436 #ifdef CONFIG_KALLSYMS 437 sp = task->thread.reg29 + schedule_mfi.frame_size; 438 439 while (in_sched_functions(pc)) 440 pc = unwind_stack(task, &sp, pc, &ra); 441 #endif 442 443 out: 444 return pc; 445 } 446 447 /* 448 * Don't forget that the stack pointer must be aligned on a 8 bytes 449 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 450 */ 451 unsigned long arch_align_stack(unsigned long sp) 452 { 453 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 454 sp -= get_random_int() & ~PAGE_MASK; 455 456 return sp & ALMASK; 457 } 458