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 default_idle(void) 47 { 48 barrier(); 49 } 50 51 void 52 cpu_idle(void) 53 { 54 while (1) { 55 void (*idle)(void) = default_idle; 56 /* FIXME -- EV6 and LCA45 know how to power down 57 the CPU. */ 58 59 while (!need_resched()) 60 idle(); 61 schedule(); 62 } 63 } 64 65 66 struct halt_info { 67 int mode; 68 char *restart_cmd; 69 }; 70 71 static void 72 common_shutdown_1(void *generic_ptr) 73 { 74 struct halt_info *how = (struct halt_info *)generic_ptr; 75 struct percpu_struct *cpup; 76 unsigned long *pflags, flags; 77 int cpuid = smp_processor_id(); 78 79 /* No point in taking interrupts anymore. */ 80 local_irq_disable(); 81 82 cpup = (struct percpu_struct *) 83 ((unsigned long)hwrpb + hwrpb->processor_offset 84 + hwrpb->processor_size * cpuid); 85 pflags = &cpup->flags; 86 flags = *pflags; 87 88 /* Clear reason to "default"; clear "bootstrap in progress". */ 89 flags &= ~0x00ff0001UL; 90 91 #ifdef CONFIG_SMP 92 /* Secondaries halt here. */ 93 if (cpuid != boot_cpuid) { 94 flags |= 0x00040000UL; /* "remain halted" */ 95 *pflags = flags; 96 clear_bit(cpuid, &cpu_present_mask); 97 halt(); 98 } 99 #endif 100 101 if (how->mode == LINUX_REBOOT_CMD_RESTART) { 102 if (!how->restart_cmd) { 103 flags |= 0x00020000UL; /* "cold bootstrap" */ 104 } else { 105 /* For SRM, we could probably set environment 106 variables to get this to work. We'd have to 107 delay this until after srm_paging_stop unless 108 we ever got srm_fixup working. 109 110 At the moment, SRM will use the last boot device, 111 but the file and flags will be the defaults, when 112 doing a "warm" bootstrap. */ 113 flags |= 0x00030000UL; /* "warm bootstrap" */ 114 } 115 } else { 116 flags |= 0x00040000UL; /* "remain halted" */ 117 } 118 *pflags = flags; 119 120 #ifdef CONFIG_SMP 121 /* Wait for the secondaries to halt. */ 122 cpu_clear(boot_cpuid, cpu_possible_map); 123 while (cpus_weight(cpu_possible_map)) 124 barrier(); 125 #endif 126 127 /* If booted from SRM, reset some of the original environment. */ 128 if (alpha_using_srm) { 129 #ifdef CONFIG_DUMMY_CONSOLE 130 /* If we've gotten here after SysRq-b, leave interrupt 131 context before taking over the console. */ 132 if (in_interrupt()) 133 irq_exit(); 134 /* This has the effect of resetting the VGA video origin. */ 135 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 136 #endif 137 pci_restore_srm_config(); 138 set_hae(srm_hae); 139 } 140 141 if (alpha_mv.kill_arch) 142 alpha_mv.kill_arch(how->mode); 143 144 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 145 /* Unfortunately, since MILO doesn't currently understand 146 the hwrpb bits above, we can't reliably halt the 147 processor and keep it halted. So just loop. */ 148 return; 149 } 150 151 if (alpha_using_srm) 152 srm_paging_stop(); 153 154 halt(); 155 } 156 157 static void 158 common_shutdown(int mode, char *restart_cmd) 159 { 160 struct halt_info args; 161 args.mode = mode; 162 args.restart_cmd = restart_cmd; 163 on_each_cpu(common_shutdown_1, &args, 1, 0); 164 } 165 166 void 167 machine_restart(char *restart_cmd) 168 { 169 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 170 } 171 172 173 void 174 machine_halt(void) 175 { 176 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 177 } 178 179 180 void 181 machine_power_off(void) 182 { 183 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 184 } 185 186 187 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 188 saved in the context it's used. */ 189 190 void 191 show_regs(struct pt_regs *regs) 192 { 193 dik_show_regs(regs, NULL); 194 } 195 196 /* 197 * Re-start a thread when doing execve() 198 */ 199 void 200 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 201 { 202 set_fs(USER_DS); 203 regs->pc = pc; 204 regs->ps = 8; 205 wrusp(sp); 206 } 207 208 /* 209 * Free current thread data structures etc.. 210 */ 211 void 212 exit_thread(void) 213 { 214 } 215 216 void 217 flush_thread(void) 218 { 219 /* Arrange for each exec'ed process to start off with a clean slate 220 with respect to the FPU. This is all exceptions disabled. */ 221 current_thread_info()->ieee_state = 0; 222 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 223 224 /* Clean slate for TLS. */ 225 current_thread_info()->pcb.unique = 0; 226 } 227 228 void 229 release_thread(struct task_struct *dead_task) 230 { 231 } 232 233 /* 234 * "alpha_clone()".. By the time we get here, the 235 * non-volatile registers have also been saved on the 236 * stack. We do some ugly pointer stuff here.. (see 237 * also copy_thread) 238 * 239 * Notice that "fork()" is implemented in terms of clone, 240 * with parameters (SIGCHLD, 0). 241 */ 242 int 243 alpha_clone(unsigned long clone_flags, unsigned long usp, 244 int __user *parent_tid, int __user *child_tid, 245 unsigned long tls_value, struct pt_regs *regs) 246 { 247 if (!usp) 248 usp = rdusp(); 249 250 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid); 251 } 252 253 int 254 alpha_vfork(struct pt_regs *regs) 255 { 256 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), 257 regs, 0, NULL, NULL); 258 } 259 260 /* 261 * Copy an alpha thread.. 262 * 263 * Note the "stack_offset" stuff: when returning to kernel mode, we need 264 * to have some extra stack-space for the kernel stack that still exists 265 * after the "ret_from_fork". When returning to user mode, we only want 266 * the space needed by the syscall stack frame (ie "struct pt_regs"). 267 * Use the passed "regs" pointer to determine how much space we need 268 * for a kernel fork(). 269 */ 270 271 int 272 copy_thread(int nr, unsigned long clone_flags, unsigned long usp, 273 unsigned long unused, 274 struct task_struct * p, struct pt_regs * regs) 275 { 276 extern void ret_from_fork(void); 277 278 struct thread_info *childti = p->thread_info; 279 struct pt_regs * childregs; 280 struct switch_stack * childstack, *stack; 281 unsigned long stack_offset, settls; 282 283 stack_offset = PAGE_SIZE - sizeof(struct pt_regs); 284 if (!(regs->ps & 8)) 285 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs; 286 childregs = (struct pt_regs *) 287 (stack_offset + PAGE_SIZE + (long) childti); 288 289 *childregs = *regs; 290 settls = regs->r20; 291 childregs->r0 = 0; 292 childregs->r19 = 0; 293 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 294 regs->r20 = 0; 295 stack = ((struct switch_stack *) regs) - 1; 296 childstack = ((struct switch_stack *) childregs) - 1; 297 *childstack = *stack; 298 childstack->r26 = (unsigned long) ret_from_fork; 299 childti->pcb.usp = usp; 300 childti->pcb.ksp = (unsigned long) childstack; 301 childti->pcb.flags = 1; /* set FEN, clear everything else */ 302 303 /* Set a new TLS for the child thread? Peek back into the 304 syscall arguments that we saved on syscall entry. Oops, 305 except we'd have clobbered it with the parent/child set 306 of r20. Read the saved copy. */ 307 /* Note: if CLONE_SETTLS is not set, then we must inherit the 308 value from the parent, which will have been set by the block 309 copy in dup_task_struct. This is non-intuitive, but is 310 required for proper operation in the case of a threaded 311 application calling fork. */ 312 if (clone_flags & CLONE_SETTLS) 313 childti->pcb.unique = settls; 314 315 return 0; 316 } 317 318 /* 319 * Fill in the user structure for an ECOFF core dump. 320 */ 321 void 322 dump_thread(struct pt_regs * pt, struct user * dump) 323 { 324 /* switch stack follows right below pt_regs: */ 325 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 326 327 dump->magic = CMAGIC; 328 dump->start_code = current->mm->start_code; 329 dump->start_data = current->mm->start_data; 330 dump->start_stack = rdusp() & ~(PAGE_SIZE - 1); 331 dump->u_tsize = ((current->mm->end_code - dump->start_code) 332 >> PAGE_SHIFT); 333 dump->u_dsize = ((current->mm->brk + PAGE_SIZE-1 - dump->start_data) 334 >> PAGE_SHIFT); 335 dump->u_ssize = (current->mm->start_stack - dump->start_stack 336 + PAGE_SIZE-1) >> PAGE_SHIFT; 337 338 /* 339 * We store the registers in an order/format that is 340 * compatible with DEC Unix/OSF/1 as this makes life easier 341 * for gdb. 342 */ 343 dump->regs[EF_V0] = pt->r0; 344 dump->regs[EF_T0] = pt->r1; 345 dump->regs[EF_T1] = pt->r2; 346 dump->regs[EF_T2] = pt->r3; 347 dump->regs[EF_T3] = pt->r4; 348 dump->regs[EF_T4] = pt->r5; 349 dump->regs[EF_T5] = pt->r6; 350 dump->regs[EF_T6] = pt->r7; 351 dump->regs[EF_T7] = pt->r8; 352 dump->regs[EF_S0] = sw->r9; 353 dump->regs[EF_S1] = sw->r10; 354 dump->regs[EF_S2] = sw->r11; 355 dump->regs[EF_S3] = sw->r12; 356 dump->regs[EF_S4] = sw->r13; 357 dump->regs[EF_S5] = sw->r14; 358 dump->regs[EF_S6] = sw->r15; 359 dump->regs[EF_A3] = pt->r19; 360 dump->regs[EF_A4] = pt->r20; 361 dump->regs[EF_A5] = pt->r21; 362 dump->regs[EF_T8] = pt->r22; 363 dump->regs[EF_T9] = pt->r23; 364 dump->regs[EF_T10] = pt->r24; 365 dump->regs[EF_T11] = pt->r25; 366 dump->regs[EF_RA] = pt->r26; 367 dump->regs[EF_T12] = pt->r27; 368 dump->regs[EF_AT] = pt->r28; 369 dump->regs[EF_SP] = rdusp(); 370 dump->regs[EF_PS] = pt->ps; 371 dump->regs[EF_PC] = pt->pc; 372 dump->regs[EF_GP] = pt->gp; 373 dump->regs[EF_A0] = pt->r16; 374 dump->regs[EF_A1] = pt->r17; 375 dump->regs[EF_A2] = pt->r18; 376 memcpy((char *)dump->regs + EF_SIZE, sw->fp, 32 * 8); 377 } 378 379 /* 380 * Fill in the user structure for a ELF core dump. 381 */ 382 void 383 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 384 { 385 /* switch stack follows right below pt_regs: */ 386 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 387 388 dest[ 0] = pt->r0; 389 dest[ 1] = pt->r1; 390 dest[ 2] = pt->r2; 391 dest[ 3] = pt->r3; 392 dest[ 4] = pt->r4; 393 dest[ 5] = pt->r5; 394 dest[ 6] = pt->r6; 395 dest[ 7] = pt->r7; 396 dest[ 8] = pt->r8; 397 dest[ 9] = sw->r9; 398 dest[10] = sw->r10; 399 dest[11] = sw->r11; 400 dest[12] = sw->r12; 401 dest[13] = sw->r13; 402 dest[14] = sw->r14; 403 dest[15] = sw->r15; 404 dest[16] = pt->r16; 405 dest[17] = pt->r17; 406 dest[18] = pt->r18; 407 dest[19] = pt->r19; 408 dest[20] = pt->r20; 409 dest[21] = pt->r21; 410 dest[22] = pt->r22; 411 dest[23] = pt->r23; 412 dest[24] = pt->r24; 413 dest[25] = pt->r25; 414 dest[26] = pt->r26; 415 dest[27] = pt->r27; 416 dest[28] = pt->r28; 417 dest[29] = pt->gp; 418 dest[30] = rdusp(); 419 dest[31] = pt->pc; 420 421 /* Once upon a time this was the PS value. Which is stupid 422 since that is always 8 for usermode. Usurped for the more 423 useful value of the thread's UNIQUE field. */ 424 dest[32] = ti->pcb.unique; 425 } 426 427 int 428 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 429 { 430 struct thread_info *ti; 431 struct pt_regs *pt; 432 433 ti = task->thread_info; 434 pt = (struct pt_regs *)((unsigned long)ti + 2*PAGE_SIZE) - 1; 435 436 dump_elf_thread(dest, pt, ti); 437 438 return 1; 439 } 440 441 int 442 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 443 { 444 struct thread_info *ti; 445 struct pt_regs *pt; 446 struct switch_stack *sw; 447 448 ti = task->thread_info; 449 pt = (struct pt_regs *)((unsigned long)ti + 2*PAGE_SIZE) - 1; 450 sw = (struct switch_stack *)pt - 1; 451 452 memcpy(dest, sw->fp, 32 * 8); 453 454 return 1; 455 } 456 457 /* 458 * sys_execve() executes a new program. 459 */ 460 asmlinkage int 461 do_sys_execve(char __user *ufilename, char __user * __user *argv, 462 char __user * __user *envp, struct pt_regs *regs) 463 { 464 int error; 465 char *filename; 466 467 filename = getname(ufilename); 468 error = PTR_ERR(filename); 469 if (IS_ERR(filename)) 470 goto out; 471 error = do_execve(filename, argv, envp, regs); 472 putname(filename); 473 out: 474 return error; 475 } 476 477 /* 478 * Return saved PC of a blocked thread. This assumes the frame 479 * pointer is the 6th saved long on the kernel stack and that the 480 * saved return address is the first long in the frame. This all 481 * holds provided the thread blocked through a call to schedule() ($15 482 * is the frame pointer in schedule() and $15 is saved at offset 48 by 483 * entry.S:do_switch_stack). 484 * 485 * Under heavy swap load I've seen this lose in an ugly way. So do 486 * some extra sanity checking on the ranges we expect these pointers 487 * to be in so that we can fail gracefully. This is just for ps after 488 * all. -- r~ 489 */ 490 491 unsigned long 492 thread_saved_pc(task_t *t) 493 { 494 unsigned long base = (unsigned long)t->thread_info; 495 unsigned long fp, sp = t->thread_info->pcb.ksp; 496 497 if (sp > base && sp+6*8 < base + 16*1024) { 498 fp = ((unsigned long*)sp)[6]; 499 if (fp > sp && fp < base + 16*1024) 500 return *(unsigned long *)fp; 501 } 502 503 return 0; 504 } 505 506 unsigned long 507 get_wchan(struct task_struct *p) 508 { 509 unsigned long schedule_frame; 510 unsigned long pc; 511 if (!p || p == current || p->state == TASK_RUNNING) 512 return 0; 513 /* 514 * This one depends on the frame size of schedule(). Do a 515 * "disass schedule" in gdb to find the frame size. Also, the 516 * code assumes that sleep_on() follows immediately after 517 * interruptible_sleep_on() and that add_timer() follows 518 * immediately after interruptible_sleep(). Ugly, isn't it? 519 * Maybe adding a wchan field to task_struct would be better, 520 * after all... 521 */ 522 523 pc = thread_saved_pc(p); 524 if (in_sched_functions(pc)) { 525 schedule_frame = ((unsigned long *)p->thread_info->pcb.ksp)[6]; 526 return ((unsigned long *)schedule_frame)[12]; 527 } 528 return pc; 529 } 530