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