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 set_cpu_present(cpuid, false); 97 set_cpu_possible(cpuid, false); 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 set_cpu_present(boot_cpuid, false); 124 set_cpu_possible(boot_cpuid, false); 125 while (cpus_weight(cpu_present_map)) 126 barrier(); 127 #endif 128 129 /* If booted from SRM, reset some of the original environment. */ 130 if (alpha_using_srm) { 131 #ifdef CONFIG_DUMMY_CONSOLE 132 /* If we've gotten here after SysRq-b, leave interrupt 133 context before taking over the console. */ 134 if (in_interrupt()) 135 irq_exit(); 136 /* This has the effect of resetting the VGA video origin. */ 137 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 138 #endif 139 pci_restore_srm_config(); 140 set_hae(srm_hae); 141 } 142 143 if (alpha_mv.kill_arch) 144 alpha_mv.kill_arch(how->mode); 145 146 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 147 /* Unfortunately, since MILO doesn't currently understand 148 the hwrpb bits above, we can't reliably halt the 149 processor and keep it halted. So just loop. */ 150 return; 151 } 152 153 if (alpha_using_srm) 154 srm_paging_stop(); 155 156 halt(); 157 } 158 159 static void 160 common_shutdown(int mode, char *restart_cmd) 161 { 162 struct halt_info args; 163 args.mode = mode; 164 args.restart_cmd = restart_cmd; 165 on_each_cpu(common_shutdown_1, &args, 0); 166 } 167 168 void 169 machine_restart(char *restart_cmd) 170 { 171 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 172 } 173 174 175 void 176 machine_halt(void) 177 { 178 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 179 } 180 181 182 void 183 machine_power_off(void) 184 { 185 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 186 } 187 188 189 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 190 saved in the context it's used. */ 191 192 void 193 show_regs(struct pt_regs *regs) 194 { 195 dik_show_regs(regs, NULL); 196 } 197 198 /* 199 * Re-start a thread when doing execve() 200 */ 201 void 202 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 203 { 204 set_fs(USER_DS); 205 regs->pc = pc; 206 regs->ps = 8; 207 wrusp(sp); 208 } 209 EXPORT_SYMBOL(start_thread); 210 211 /* 212 * Free current thread data structures etc.. 213 */ 214 void 215 exit_thread(void) 216 { 217 } 218 219 void 220 flush_thread(void) 221 { 222 /* Arrange for each exec'ed process to start off with a clean slate 223 with respect to the FPU. This is all exceptions disabled. */ 224 current_thread_info()->ieee_state = 0; 225 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 226 227 /* Clean slate for TLS. */ 228 current_thread_info()->pcb.unique = 0; 229 } 230 231 void 232 release_thread(struct task_struct *dead_task) 233 { 234 } 235 236 /* 237 * "alpha_clone()".. By the time we get here, the 238 * non-volatile registers have also been saved on the 239 * stack. We do some ugly pointer stuff here.. (see 240 * also copy_thread) 241 * 242 * Notice that "fork()" is implemented in terms of clone, 243 * with parameters (SIGCHLD, 0). 244 */ 245 int 246 alpha_clone(unsigned long clone_flags, unsigned long usp, 247 int __user *parent_tid, int __user *child_tid, 248 unsigned long tls_value, struct pt_regs *regs) 249 { 250 if (!usp) 251 usp = rdusp(); 252 253 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid); 254 } 255 256 int 257 alpha_vfork(struct pt_regs *regs) 258 { 259 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), 260 regs, 0, NULL, NULL); 261 } 262 263 /* 264 * Copy an alpha thread.. 265 * 266 * Note the "stack_offset" stuff: when returning to kernel mode, we need 267 * to have some extra stack-space for the kernel stack that still exists 268 * after the "ret_from_fork". When returning to user mode, we only want 269 * the space needed by the syscall stack frame (ie "struct pt_regs"). 270 * Use the passed "regs" pointer to determine how much space we need 271 * for a kernel fork(). 272 */ 273 274 int 275 copy_thread(unsigned long clone_flags, unsigned long usp, 276 unsigned long unused, 277 struct task_struct * p, struct pt_regs * regs) 278 { 279 extern void ret_from_fork(void); 280 281 struct thread_info *childti = task_thread_info(p); 282 struct pt_regs * childregs; 283 struct switch_stack * childstack, *stack; 284 unsigned long stack_offset, settls; 285 286 stack_offset = PAGE_SIZE - sizeof(struct pt_regs); 287 if (!(regs->ps & 8)) 288 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs; 289 childregs = (struct pt_regs *) 290 (stack_offset + PAGE_SIZE + task_stack_page(p)); 291 292 *childregs = *regs; 293 settls = regs->r20; 294 childregs->r0 = 0; 295 childregs->r19 = 0; 296 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 297 regs->r20 = 0; 298 stack = ((struct switch_stack *) regs) - 1; 299 childstack = ((struct switch_stack *) childregs) - 1; 300 *childstack = *stack; 301 childstack->r26 = (unsigned long) ret_from_fork; 302 childti->pcb.usp = usp; 303 childti->pcb.ksp = (unsigned long) childstack; 304 childti->pcb.flags = 1; /* set FEN, clear everything else */ 305 306 /* Set a new TLS for the child thread? Peek back into the 307 syscall arguments that we saved on syscall entry. Oops, 308 except we'd have clobbered it with the parent/child set 309 of r20. Read the saved copy. */ 310 /* Note: if CLONE_SETTLS is not set, then we must inherit the 311 value from the parent, which will have been set by the block 312 copy in dup_task_struct. This is non-intuitive, but is 313 required for proper operation in the case of a threaded 314 application calling fork. */ 315 if (clone_flags & CLONE_SETTLS) 316 childti->pcb.unique = settls; 317 318 return 0; 319 } 320 321 /* 322 * Fill in the user structure for a ELF core dump. 323 */ 324 void 325 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 326 { 327 /* switch stack follows right below pt_regs: */ 328 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 329 330 dest[ 0] = pt->r0; 331 dest[ 1] = pt->r1; 332 dest[ 2] = pt->r2; 333 dest[ 3] = pt->r3; 334 dest[ 4] = pt->r4; 335 dest[ 5] = pt->r5; 336 dest[ 6] = pt->r6; 337 dest[ 7] = pt->r7; 338 dest[ 8] = pt->r8; 339 dest[ 9] = sw->r9; 340 dest[10] = sw->r10; 341 dest[11] = sw->r11; 342 dest[12] = sw->r12; 343 dest[13] = sw->r13; 344 dest[14] = sw->r14; 345 dest[15] = sw->r15; 346 dest[16] = pt->r16; 347 dest[17] = pt->r17; 348 dest[18] = pt->r18; 349 dest[19] = pt->r19; 350 dest[20] = pt->r20; 351 dest[21] = pt->r21; 352 dest[22] = pt->r22; 353 dest[23] = pt->r23; 354 dest[24] = pt->r24; 355 dest[25] = pt->r25; 356 dest[26] = pt->r26; 357 dest[27] = pt->r27; 358 dest[28] = pt->r28; 359 dest[29] = pt->gp; 360 dest[30] = rdusp(); 361 dest[31] = pt->pc; 362 363 /* Once upon a time this was the PS value. Which is stupid 364 since that is always 8 for usermode. Usurped for the more 365 useful value of the thread's UNIQUE field. */ 366 dest[32] = ti->pcb.unique; 367 } 368 EXPORT_SYMBOL(dump_elf_thread); 369 370 int 371 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 372 { 373 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 374 return 1; 375 } 376 EXPORT_SYMBOL(dump_elf_task); 377 378 int 379 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 380 { 381 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 382 memcpy(dest, sw->fp, 32 * 8); 383 return 1; 384 } 385 EXPORT_SYMBOL(dump_elf_task_fp); 386 387 /* 388 * sys_execve() executes a new program. 389 */ 390 asmlinkage int 391 do_sys_execve(char __user *ufilename, char __user * __user *argv, 392 char __user * __user *envp, struct pt_regs *regs) 393 { 394 int error; 395 char *filename; 396 397 filename = getname(ufilename); 398 error = PTR_ERR(filename); 399 if (IS_ERR(filename)) 400 goto out; 401 error = do_execve(filename, argv, envp, regs); 402 putname(filename); 403 out: 404 return error; 405 } 406 407 /* 408 * Return saved PC of a blocked thread. This assumes the frame 409 * pointer is the 6th saved long on the kernel stack and that the 410 * saved return address is the first long in the frame. This all 411 * holds provided the thread blocked through a call to schedule() ($15 412 * is the frame pointer in schedule() and $15 is saved at offset 48 by 413 * entry.S:do_switch_stack). 414 * 415 * Under heavy swap load I've seen this lose in an ugly way. So do 416 * some extra sanity checking on the ranges we expect these pointers 417 * to be in so that we can fail gracefully. This is just for ps after 418 * all. -- r~ 419 */ 420 421 unsigned long 422 thread_saved_pc(struct task_struct *t) 423 { 424 unsigned long base = (unsigned long)task_stack_page(t); 425 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 426 427 if (sp > base && sp+6*8 < base + 16*1024) { 428 fp = ((unsigned long*)sp)[6]; 429 if (fp > sp && fp < base + 16*1024) 430 return *(unsigned long *)fp; 431 } 432 433 return 0; 434 } 435 436 unsigned long 437 get_wchan(struct task_struct *p) 438 { 439 unsigned long schedule_frame; 440 unsigned long pc; 441 if (!p || p == current || p->state == TASK_RUNNING) 442 return 0; 443 /* 444 * This one depends on the frame size of schedule(). Do a 445 * "disass schedule" in gdb to find the frame size. Also, the 446 * code assumes that sleep_on() follows immediately after 447 * interruptible_sleep_on() and that add_timer() follows 448 * immediately after interruptible_sleep(). Ugly, isn't it? 449 * Maybe adding a wchan field to task_struct would be better, 450 * after all... 451 */ 452 453 pc = thread_saved_pc(p); 454 if (in_sched_functions(pc)) { 455 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 456 return ((unsigned long *)schedule_frame)[12]; 457 } 458 return pc; 459 } 460