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 32 #include <asm/reg.h> 33 #include <asm/uaccess.h> 34 #include <asm/system.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 set_thread_flag(TIF_POLLING_NRFLAG); 53 54 while (1) { 55 /* FIXME -- EV6 and LCA45 know how to power down 56 the CPU. */ 57 58 while (!need_resched()) 59 cpu_relax(); 60 schedule(); 61 } 62 } 63 64 65 struct halt_info { 66 int mode; 67 char *restart_cmd; 68 }; 69 70 static void 71 common_shutdown_1(void *generic_ptr) 72 { 73 struct halt_info *how = (struct halt_info *)generic_ptr; 74 struct percpu_struct *cpup; 75 unsigned long *pflags, flags; 76 int cpuid = smp_processor_id(); 77 78 /* No point in taking interrupts anymore. */ 79 local_irq_disable(); 80 81 cpup = (struct percpu_struct *) 82 ((unsigned long)hwrpb + hwrpb->processor_offset 83 + hwrpb->processor_size * cpuid); 84 pflags = &cpup->flags; 85 flags = *pflags; 86 87 /* Clear reason to "default"; clear "bootstrap in progress". */ 88 flags &= ~0x00ff0001UL; 89 90 #ifdef CONFIG_SMP 91 /* Secondaries halt here. */ 92 if (cpuid != boot_cpuid) { 93 flags |= 0x00040000UL; /* "remain halted" */ 94 *pflags = flags; 95 set_cpu_present(cpuid, false); 96 set_cpu_possible(cpuid, false); 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 set_cpu_present(boot_cpuid, false); 123 set_cpu_possible(boot_cpuid, false); 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, 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 EXPORT_SYMBOL(start_thread); 209 210 /* 211 * Free current thread data structures etc.. 212 */ 213 void 214 exit_thread(void) 215 { 216 } 217 218 void 219 flush_thread(void) 220 { 221 /* Arrange for each exec'ed process to start off with a clean slate 222 with respect to the FPU. This is all exceptions disabled. */ 223 current_thread_info()->ieee_state = 0; 224 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 225 226 /* Clean slate for TLS. */ 227 current_thread_info()->pcb.unique = 0; 228 } 229 230 void 231 release_thread(struct task_struct *dead_task) 232 { 233 } 234 235 /* 236 * "alpha_clone()".. By the time we get here, the 237 * non-volatile registers have also been saved on the 238 * stack. We do some ugly pointer stuff here.. (see 239 * also copy_thread) 240 * 241 * Notice that "fork()" is implemented in terms of clone, 242 * with parameters (SIGCHLD, 0). 243 */ 244 int 245 alpha_clone(unsigned long clone_flags, unsigned long usp, 246 int __user *parent_tid, int __user *child_tid, 247 unsigned long tls_value, struct pt_regs *regs) 248 { 249 if (!usp) 250 usp = rdusp(); 251 252 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid); 253 } 254 255 int 256 alpha_vfork(struct pt_regs *regs) 257 { 258 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), 259 regs, 0, NULL, NULL); 260 } 261 262 /* 263 * Copy an alpha thread.. 264 * 265 * Note the "stack_offset" stuff: when returning to kernel mode, we need 266 * to have some extra stack-space for the kernel stack that still exists 267 * after the "ret_from_fork". When returning to user mode, we only want 268 * the space needed by the syscall stack frame (ie "struct pt_regs"). 269 * Use the passed "regs" pointer to determine how much space we need 270 * for a kernel fork(). 271 */ 272 273 int 274 copy_thread(unsigned long clone_flags, unsigned long usp, 275 unsigned long unused, 276 struct task_struct * p, struct pt_regs * regs) 277 { 278 extern void ret_from_fork(void); 279 280 struct thread_info *childti = task_thread_info(p); 281 struct pt_regs * childregs; 282 struct switch_stack * childstack, *stack; 283 unsigned long stack_offset, settls; 284 285 stack_offset = PAGE_SIZE - sizeof(struct pt_regs); 286 if (!(regs->ps & 8)) 287 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs; 288 childregs = (struct pt_regs *) 289 (stack_offset + PAGE_SIZE + task_stack_page(p)); 290 291 *childregs = *regs; 292 settls = regs->r20; 293 childregs->r0 = 0; 294 childregs->r19 = 0; 295 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 296 regs->r20 = 0; 297 stack = ((struct switch_stack *) regs) - 1; 298 childstack = ((struct switch_stack *) childregs) - 1; 299 *childstack = *stack; 300 childstack->r26 = (unsigned long) ret_from_fork; 301 childti->pcb.usp = usp; 302 childti->pcb.ksp = (unsigned long) childstack; 303 childti->pcb.flags = 1; /* set FEN, clear everything else */ 304 305 /* Set a new TLS for the child thread? Peek back into the 306 syscall arguments that we saved on syscall entry. Oops, 307 except we'd have clobbered it with the parent/child set 308 of r20. Read the saved copy. */ 309 /* Note: if CLONE_SETTLS is not set, then we must inherit the 310 value from the parent, which will have been set by the block 311 copy in dup_task_struct. This is non-intuitive, but is 312 required for proper operation in the case of a threaded 313 application calling fork. */ 314 if (clone_flags & CLONE_SETTLS) 315 childti->pcb.unique = settls; 316 317 return 0; 318 } 319 320 /* 321 * Fill in the user structure for a ELF core dump. 322 */ 323 void 324 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 325 { 326 /* switch stack follows right below pt_regs: */ 327 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 328 329 dest[ 0] = pt->r0; 330 dest[ 1] = pt->r1; 331 dest[ 2] = pt->r2; 332 dest[ 3] = pt->r3; 333 dest[ 4] = pt->r4; 334 dest[ 5] = pt->r5; 335 dest[ 6] = pt->r6; 336 dest[ 7] = pt->r7; 337 dest[ 8] = pt->r8; 338 dest[ 9] = sw->r9; 339 dest[10] = sw->r10; 340 dest[11] = sw->r11; 341 dest[12] = sw->r12; 342 dest[13] = sw->r13; 343 dest[14] = sw->r14; 344 dest[15] = sw->r15; 345 dest[16] = pt->r16; 346 dest[17] = pt->r17; 347 dest[18] = pt->r18; 348 dest[19] = pt->r19; 349 dest[20] = pt->r20; 350 dest[21] = pt->r21; 351 dest[22] = pt->r22; 352 dest[23] = pt->r23; 353 dest[24] = pt->r24; 354 dest[25] = pt->r25; 355 dest[26] = pt->r26; 356 dest[27] = pt->r27; 357 dest[28] = pt->r28; 358 dest[29] = pt->gp; 359 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 360 dest[31] = pt->pc; 361 362 /* Once upon a time this was the PS value. Which is stupid 363 since that is always 8 for usermode. Usurped for the more 364 useful value of the thread's UNIQUE field. */ 365 dest[32] = ti->pcb.unique; 366 } 367 EXPORT_SYMBOL(dump_elf_thread); 368 369 int 370 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 371 { 372 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 373 return 1; 374 } 375 EXPORT_SYMBOL(dump_elf_task); 376 377 int 378 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 379 { 380 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 381 memcpy(dest, sw->fp, 32 * 8); 382 return 1; 383 } 384 EXPORT_SYMBOL(dump_elf_task_fp); 385 386 /* 387 * sys_execve() executes a new program. 388 */ 389 asmlinkage int 390 do_sys_execve(const char __user *ufilename, 391 const char __user *const __user *argv, 392 const char __user *const __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