1 /* 2 * linux/arch/alpha/kernel/process.c 3 * 4 * Copyright (C) 1995 Linus Torvalds 5 */ 6 7 /* 8 * This file handles the architecture-dependent parts of process handling. 9 */ 10 11 #include <linux/config.h> 12 #include <linux/errno.h> 13 #include <linux/module.h> 14 #include <linux/sched.h> 15 #include <linux/kernel.h> 16 #include <linux/mm.h> 17 #include <linux/smp.h> 18 #include <linux/smp_lock.h> 19 #include <linux/stddef.h> 20 #include <linux/unistd.h> 21 #include <linux/ptrace.h> 22 #include <linux/slab.h> 23 #include <linux/user.h> 24 #include <linux/a.out.h> 25 #include <linux/utsname.h> 26 #include <linux/time.h> 27 #include <linux/major.h> 28 #include <linux/stat.h> 29 #include <linux/mman.h> 30 #include <linux/elfcore.h> 31 #include <linux/reboot.h> 32 #include <linux/tty.h> 33 #include <linux/console.h> 34 35 #include <asm/reg.h> 36 #include <asm/uaccess.h> 37 #include <asm/system.h> 38 #include <asm/io.h> 39 #include <asm/pgtable.h> 40 #include <asm/hwrpb.h> 41 #include <asm/fpu.h> 42 43 #include "proto.h" 44 #include "pci_impl.h" 45 46 void 47 cpu_idle(void) 48 { 49 set_thread_flag(TIF_POLLING_NRFLAG); 50 51 while (1) { 52 /* FIXME -- EV6 and LCA45 know how to power down 53 the CPU. */ 54 55 while (!need_resched()) 56 cpu_relax(); 57 schedule(); 58 } 59 } 60 61 62 struct halt_info { 63 int mode; 64 char *restart_cmd; 65 }; 66 67 static void 68 common_shutdown_1(void *generic_ptr) 69 { 70 struct halt_info *how = (struct halt_info *)generic_ptr; 71 struct percpu_struct *cpup; 72 unsigned long *pflags, flags; 73 int cpuid = smp_processor_id(); 74 75 /* No point in taking interrupts anymore. */ 76 local_irq_disable(); 77 78 cpup = (struct percpu_struct *) 79 ((unsigned long)hwrpb + hwrpb->processor_offset 80 + hwrpb->processor_size * cpuid); 81 pflags = &cpup->flags; 82 flags = *pflags; 83 84 /* Clear reason to "default"; clear "bootstrap in progress". */ 85 flags &= ~0x00ff0001UL; 86 87 #ifdef CONFIG_SMP 88 /* Secondaries halt here. */ 89 if (cpuid != boot_cpuid) { 90 flags |= 0x00040000UL; /* "remain halted" */ 91 *pflags = flags; 92 clear_bit(cpuid, &cpu_present_mask); 93 halt(); 94 } 95 #endif 96 97 if (how->mode == LINUX_REBOOT_CMD_RESTART) { 98 if (!how->restart_cmd) { 99 flags |= 0x00020000UL; /* "cold bootstrap" */ 100 } else { 101 /* For SRM, we could probably set environment 102 variables to get this to work. We'd have to 103 delay this until after srm_paging_stop unless 104 we ever got srm_fixup working. 105 106 At the moment, SRM will use the last boot device, 107 but the file and flags will be the defaults, when 108 doing a "warm" bootstrap. */ 109 flags |= 0x00030000UL; /* "warm bootstrap" */ 110 } 111 } else { 112 flags |= 0x00040000UL; /* "remain halted" */ 113 } 114 *pflags = flags; 115 116 #ifdef CONFIG_SMP 117 /* Wait for the secondaries to halt. */ 118 cpu_clear(boot_cpuid, cpu_possible_map); 119 while (cpus_weight(cpu_possible_map)) 120 barrier(); 121 #endif 122 123 /* If booted from SRM, reset some of the original environment. */ 124 if (alpha_using_srm) { 125 #ifdef CONFIG_DUMMY_CONSOLE 126 /* If we've gotten here after SysRq-b, leave interrupt 127 context before taking over the console. */ 128 if (in_interrupt()) 129 irq_exit(); 130 /* This has the effect of resetting the VGA video origin. */ 131 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 132 #endif 133 pci_restore_srm_config(); 134 set_hae(srm_hae); 135 } 136 137 if (alpha_mv.kill_arch) 138 alpha_mv.kill_arch(how->mode); 139 140 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 141 /* Unfortunately, since MILO doesn't currently understand 142 the hwrpb bits above, we can't reliably halt the 143 processor and keep it halted. So just loop. */ 144 return; 145 } 146 147 if (alpha_using_srm) 148 srm_paging_stop(); 149 150 halt(); 151 } 152 153 static void 154 common_shutdown(int mode, char *restart_cmd) 155 { 156 struct halt_info args; 157 args.mode = mode; 158 args.restart_cmd = restart_cmd; 159 on_each_cpu(common_shutdown_1, &args, 1, 0); 160 } 161 162 void 163 machine_restart(char *restart_cmd) 164 { 165 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 166 } 167 168 169 void 170 machine_halt(void) 171 { 172 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 173 } 174 175 176 void 177 machine_power_off(void) 178 { 179 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 180 } 181 182 183 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 184 saved in the context it's used. */ 185 186 void 187 show_regs(struct pt_regs *regs) 188 { 189 dik_show_regs(regs, NULL); 190 } 191 192 /* 193 * Re-start a thread when doing execve() 194 */ 195 void 196 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 197 { 198 set_fs(USER_DS); 199 regs->pc = pc; 200 regs->ps = 8; 201 wrusp(sp); 202 } 203 204 /* 205 * Free current thread data structures etc.. 206 */ 207 void 208 exit_thread(void) 209 { 210 } 211 212 void 213 flush_thread(void) 214 { 215 /* Arrange for each exec'ed process to start off with a clean slate 216 with respect to the FPU. This is all exceptions disabled. */ 217 current_thread_info()->ieee_state = 0; 218 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 219 220 /* Clean slate for TLS. */ 221 current_thread_info()->pcb.unique = 0; 222 } 223 224 void 225 release_thread(struct task_struct *dead_task) 226 { 227 } 228 229 /* 230 * "alpha_clone()".. By the time we get here, the 231 * non-volatile registers have also been saved on the 232 * stack. We do some ugly pointer stuff here.. (see 233 * also copy_thread) 234 * 235 * Notice that "fork()" is implemented in terms of clone, 236 * with parameters (SIGCHLD, 0). 237 */ 238 int 239 alpha_clone(unsigned long clone_flags, unsigned long usp, 240 int __user *parent_tid, int __user *child_tid, 241 unsigned long tls_value, struct pt_regs *regs) 242 { 243 if (!usp) 244 usp = rdusp(); 245 246 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid); 247 } 248 249 int 250 alpha_vfork(struct pt_regs *regs) 251 { 252 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), 253 regs, 0, NULL, NULL); 254 } 255 256 /* 257 * Copy an alpha thread.. 258 * 259 * Note the "stack_offset" stuff: when returning to kernel mode, we need 260 * to have some extra stack-space for the kernel stack that still exists 261 * after the "ret_from_fork". When returning to user mode, we only want 262 * the space needed by the syscall stack frame (ie "struct pt_regs"). 263 * Use the passed "regs" pointer to determine how much space we need 264 * for a kernel fork(). 265 */ 266 267 int 268 copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 269 unsigned long unused, 270 struct task_struct * p, struct pt_regs * regs) 271 { 272 extern void ret_from_fork(void); 273 274 struct thread_info *childti = p->thread_info; 275 struct pt_regs * childregs; 276 struct switch_stack * childstack, *stack; 277 unsigned long stack_offset, settls; 278 279 stack_offset = PAGE_SIZE - sizeof(struct pt_regs); 280 if (!(regs->ps & 8)) 281 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs; 282 childregs = (struct pt_regs *) 283 (stack_offset + PAGE_SIZE + (long) childti); 284 285 *childregs = *regs; 286 settls = regs->r20; 287 childregs->r0 = 0; 288 childregs->r19 = 0; 289 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 290 regs->r20 = 0; 291 stack = ((struct switch_stack *) regs) - 1; 292 childstack = ((struct switch_stack *) childregs) - 1; 293 *childstack = *stack; 294 childstack->r26 = (unsigned long) ret_from_fork; 295 childti->pcb.usp = usp; 296 childti->pcb.ksp = (unsigned long) childstack; 297 childti->pcb.flags = 1; /* set FEN, clear everything else */ 298 299 /* Set a new TLS for the child thread? Peek back into the 300 syscall arguments that we saved on syscall entry. Oops, 301 except we'd have clobbered it with the parent/child set 302 of r20. Read the saved copy. */ 303 /* Note: if CLONE_SETTLS is not set, then we must inherit the 304 value from the parent, which will have been set by the block 305 copy in dup_task_struct. This is non-intuitive, but is 306 required for proper operation in the case of a threaded 307 application calling fork. */ 308 if (clone_flags & CLONE_SETTLS) 309 childti->pcb.unique = settls; 310 311 return 0; 312 } 313 314 /* 315 * Fill in the user structure for an ECOFF core dump. 316 */ 317 void 318 dump_thread(struct pt_regs * pt, struct user * dump) 319 { 320 /* switch stack follows right below pt_regs: */ 321 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 322 323 dump->magic = CMAGIC; 324 dump->start_code = current->mm->start_code; 325 dump->start_data = current->mm->start_data; 326 dump->start_stack = rdusp() & ~(PAGE_SIZE - 1); 327 dump->u_tsize = ((current->mm->end_code - dump->start_code) 328 >> PAGE_SHIFT); 329 dump->u_dsize = ((current->mm->brk + PAGE_SIZE-1 - dump->start_data) 330 >> PAGE_SHIFT); 331 dump->u_ssize = (current->mm->start_stack - dump->start_stack 332 + PAGE_SIZE-1) >> PAGE_SHIFT; 333 334 /* 335 * We store the registers in an order/format that is 336 * compatible with DEC Unix/OSF/1 as this makes life easier 337 * for gdb. 338 */ 339 dump->regs[EF_V0] = pt->r0; 340 dump->regs[EF_T0] = pt->r1; 341 dump->regs[EF_T1] = pt->r2; 342 dump->regs[EF_T2] = pt->r3; 343 dump->regs[EF_T3] = pt->r4; 344 dump->regs[EF_T4] = pt->r5; 345 dump->regs[EF_T5] = pt->r6; 346 dump->regs[EF_T6] = pt->r7; 347 dump->regs[EF_T7] = pt->r8; 348 dump->regs[EF_S0] = sw->r9; 349 dump->regs[EF_S1] = sw->r10; 350 dump->regs[EF_S2] = sw->r11; 351 dump->regs[EF_S3] = sw->r12; 352 dump->regs[EF_S4] = sw->r13; 353 dump->regs[EF_S5] = sw->r14; 354 dump->regs[EF_S6] = sw->r15; 355 dump->regs[EF_A3] = pt->r19; 356 dump->regs[EF_A4] = pt->r20; 357 dump->regs[EF_A5] = pt->r21; 358 dump->regs[EF_T8] = pt->r22; 359 dump->regs[EF_T9] = pt->r23; 360 dump->regs[EF_T10] = pt->r24; 361 dump->regs[EF_T11] = pt->r25; 362 dump->regs[EF_RA] = pt->r26; 363 dump->regs[EF_T12] = pt->r27; 364 dump->regs[EF_AT] = pt->r28; 365 dump->regs[EF_SP] = rdusp(); 366 dump->regs[EF_PS] = pt->ps; 367 dump->regs[EF_PC] = pt->pc; 368 dump->regs[EF_GP] = pt->gp; 369 dump->regs[EF_A0] = pt->r16; 370 dump->regs[EF_A1] = pt->r17; 371 dump->regs[EF_A2] = pt->r18; 372 memcpy((char *)dump->regs + EF_SIZE, sw->fp, 32 * 8); 373 } 374 375 /* 376 * Fill in the user structure for a ELF core dump. 377 */ 378 void 379 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 380 { 381 /* switch stack follows right below pt_regs: */ 382 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 383 384 dest[ 0] = pt->r0; 385 dest[ 1] = pt->r1; 386 dest[ 2] = pt->r2; 387 dest[ 3] = pt->r3; 388 dest[ 4] = pt->r4; 389 dest[ 5] = pt->r5; 390 dest[ 6] = pt->r6; 391 dest[ 7] = pt->r7; 392 dest[ 8] = pt->r8; 393 dest[ 9] = sw->r9; 394 dest[10] = sw->r10; 395 dest[11] = sw->r11; 396 dest[12] = sw->r12; 397 dest[13] = sw->r13; 398 dest[14] = sw->r14; 399 dest[15] = sw->r15; 400 dest[16] = pt->r16; 401 dest[17] = pt->r17; 402 dest[18] = pt->r18; 403 dest[19] = pt->r19; 404 dest[20] = pt->r20; 405 dest[21] = pt->r21; 406 dest[22] = pt->r22; 407 dest[23] = pt->r23; 408 dest[24] = pt->r24; 409 dest[25] = pt->r25; 410 dest[26] = pt->r26; 411 dest[27] = pt->r27; 412 dest[28] = pt->r28; 413 dest[29] = pt->gp; 414 dest[30] = rdusp(); 415 dest[31] = pt->pc; 416 417 /* Once upon a time this was the PS value. Which is stupid 418 since that is always 8 for usermode. Usurped for the more 419 useful value of the thread's UNIQUE field. */ 420 dest[32] = ti->pcb.unique; 421 } 422 423 int 424 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 425 { 426 struct thread_info *ti; 427 struct pt_regs *pt; 428 429 ti = task->thread_info; 430 pt = (struct pt_regs *)((unsigned long)ti + 2*PAGE_SIZE) - 1; 431 432 dump_elf_thread(dest, pt, ti); 433 434 return 1; 435 } 436 437 int 438 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 439 { 440 struct thread_info *ti; 441 struct pt_regs *pt; 442 struct switch_stack *sw; 443 444 ti = task->thread_info; 445 pt = (struct pt_regs *)((unsigned long)ti + 2*PAGE_SIZE) - 1; 446 sw = (struct switch_stack *)pt - 1; 447 448 memcpy(dest, sw->fp, 32 * 8); 449 450 return 1; 451 } 452 453 /* 454 * sys_execve() executes a new program. 455 */ 456 asmlinkage int 457 do_sys_execve(char __user *ufilename, char __user * __user *argv, 458 char __user * __user *envp, struct pt_regs *regs) 459 { 460 int error; 461 char *filename; 462 463 filename = getname(ufilename); 464 error = PTR_ERR(filename); 465 if (IS_ERR(filename)) 466 goto out; 467 error = do_execve(filename, argv, envp, regs); 468 putname(filename); 469 out: 470 return error; 471 } 472 473 /* 474 * Return saved PC of a blocked thread. This assumes the frame 475 * pointer is the 6th saved long on the kernel stack and that the 476 * saved return address is the first long in the frame. This all 477 * holds provided the thread blocked through a call to schedule() ($15 478 * is the frame pointer in schedule() and $15 is saved at offset 48 by 479 * entry.S:do_switch_stack). 480 * 481 * Under heavy swap load I've seen this lose in an ugly way. So do 482 * some extra sanity checking on the ranges we expect these pointers 483 * to be in so that we can fail gracefully. This is just for ps after 484 * all. -- r~ 485 */ 486 487 unsigned long 488 thread_saved_pc(task_t *t) 489 { 490 unsigned long base = (unsigned long)t->thread_info; 491 unsigned long fp, sp = t->thread_info->pcb.ksp; 492 493 if (sp > base && sp+6*8 < base + 16*1024) { 494 fp = ((unsigned long*)sp)[6]; 495 if (fp > sp && fp < base + 16*1024) 496 return *(unsigned long *)fp; 497 } 498 499 return 0; 500 } 501 502 unsigned long 503 get_wchan(struct task_struct *p) 504 { 505 unsigned long schedule_frame; 506 unsigned long pc; 507 if (!p || p == current || p->state == TASK_RUNNING) 508 return 0; 509 /* 510 * This one depends on the frame size of schedule(). Do a 511 * "disass schedule" in gdb to find the frame size. Also, the 512 * code assumes that sleep_on() follows immediately after 513 * interruptible_sleep_on() and that add_timer() follows 514 * immediately after interruptible_sleep(). Ugly, isn't it? 515 * Maybe adding a wchan field to task_struct would be better, 516 * after all... 517 */ 518 519 pc = thread_saved_pc(p); 520 if (in_sched_functions(pc)) { 521 schedule_frame = ((unsigned long *)p->thread_info->pcb.ksp)[6]; 522 return ((unsigned long *)schedule_frame)[12]; 523 } 524 return pc; 525 } 526