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