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/slab.h> 21 #include <linux/user.h> 22 #include <linux/utsname.h> 23 #include <linux/time.h> 24 #include <linux/major.h> 25 #include <linux/stat.h> 26 #include <linux/vt.h> 27 #include <linux/mman.h> 28 #include <linux/elfcore.h> 29 #include <linux/reboot.h> 30 #include <linux/tty.h> 31 #include <linux/console.h> 32 33 #include <asm/reg.h> 34 #include <asm/uaccess.h> 35 #include <asm/system.h> 36 #include <asm/io.h> 37 #include <asm/pgtable.h> 38 #include <asm/hwrpb.h> 39 #include <asm/fpu.h> 40 41 #include "proto.h" 42 #include "pci_impl.h" 43 44 /* 45 * Power off function, if any 46 */ 47 void (*pm_power_off)(void) = machine_power_off; 48 EXPORT_SYMBOL(pm_power_off); 49 50 void 51 cpu_idle(void) 52 { 53 set_thread_flag(TIF_POLLING_NRFLAG); 54 55 while (1) { 56 /* FIXME -- EV6 and LCA45 know how to power down 57 the CPU. */ 58 59 while (!need_resched()) 60 cpu_relax(); 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 cpu_clear(cpuid, cpu_present_map); 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_present_map); 123 while (cpus_weight(cpu_present_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, 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 EXPORT_SYMBOL(start_thread); 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 a ELF core dump. 321 */ 322 void 323 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 324 { 325 /* switch stack follows right below pt_regs: */ 326 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 327 328 dest[ 0] = pt->r0; 329 dest[ 1] = pt->r1; 330 dest[ 2] = pt->r2; 331 dest[ 3] = pt->r3; 332 dest[ 4] = pt->r4; 333 dest[ 5] = pt->r5; 334 dest[ 6] = pt->r6; 335 dest[ 7] = pt->r7; 336 dest[ 8] = pt->r8; 337 dest[ 9] = sw->r9; 338 dest[10] = sw->r10; 339 dest[11] = sw->r11; 340 dest[12] = sw->r12; 341 dest[13] = sw->r13; 342 dest[14] = sw->r14; 343 dest[15] = sw->r15; 344 dest[16] = pt->r16; 345 dest[17] = pt->r17; 346 dest[18] = pt->r18; 347 dest[19] = pt->r19; 348 dest[20] = pt->r20; 349 dest[21] = pt->r21; 350 dest[22] = pt->r22; 351 dest[23] = pt->r23; 352 dest[24] = pt->r24; 353 dest[25] = pt->r25; 354 dest[26] = pt->r26; 355 dest[27] = pt->r27; 356 dest[28] = pt->r28; 357 dest[29] = pt->gp; 358 dest[30] = rdusp(); 359 dest[31] = pt->pc; 360 361 /* Once upon a time this was the PS value. Which is stupid 362 since that is always 8 for usermode. Usurped for the more 363 useful value of the thread's UNIQUE field. */ 364 dest[32] = ti->pcb.unique; 365 } 366 EXPORT_SYMBOL(dump_elf_thread); 367 368 int 369 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 370 { 371 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 372 return 1; 373 } 374 EXPORT_SYMBOL(dump_elf_task); 375 376 int 377 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 378 { 379 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 380 memcpy(dest, sw->fp, 32 * 8); 381 return 1; 382 } 383 EXPORT_SYMBOL(dump_elf_task_fp); 384 385 /* 386 * sys_execve() executes a new program. 387 */ 388 asmlinkage int 389 do_sys_execve(char __user *ufilename, char __user * __user *argv, 390 char __user * __user *envp, struct pt_regs *regs) 391 { 392 int error; 393 char *filename; 394 395 filename = getname(ufilename); 396 error = PTR_ERR(filename); 397 if (IS_ERR(filename)) 398 goto out; 399 error = do_execve(filename, argv, envp, regs); 400 putname(filename); 401 out: 402 return error; 403 } 404 405 /* 406 * Return saved PC of a blocked thread. This assumes the frame 407 * pointer is the 6th saved long on the kernel stack and that the 408 * saved return address is the first long in the frame. This all 409 * holds provided the thread blocked through a call to schedule() ($15 410 * is the frame pointer in schedule() and $15 is saved at offset 48 by 411 * entry.S:do_switch_stack). 412 * 413 * Under heavy swap load I've seen this lose in an ugly way. So do 414 * some extra sanity checking on the ranges we expect these pointers 415 * to be in so that we can fail gracefully. This is just for ps after 416 * all. -- r~ 417 */ 418 419 unsigned long 420 thread_saved_pc(struct task_struct *t) 421 { 422 unsigned long base = (unsigned long)task_stack_page(t); 423 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 424 425 if (sp > base && sp+6*8 < base + 16*1024) { 426 fp = ((unsigned long*)sp)[6]; 427 if (fp > sp && fp < base + 16*1024) 428 return *(unsigned long *)fp; 429 } 430 431 return 0; 432 } 433 434 unsigned long 435 get_wchan(struct task_struct *p) 436 { 437 unsigned long schedule_frame; 438 unsigned long pc; 439 if (!p || p == current || p->state == TASK_RUNNING) 440 return 0; 441 /* 442 * This one depends on the frame size of schedule(). Do a 443 * "disass schedule" in gdb to find the frame size. Also, the 444 * code assumes that sleep_on() follows immediately after 445 * interruptible_sleep_on() and that add_timer() follows 446 * immediately after interruptible_sleep(). Ugly, isn't it? 447 * Maybe adding a wchan field to task_struct would be better, 448 * after all... 449 */ 450 451 pc = thread_saved_pc(p); 452 if (in_sched_functions(pc)) { 453 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 454 return ((unsigned long *)schedule_frame)[12]; 455 } 456 return pc; 457 } 458