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 */ 46void (*pm_power_off)(void) = machine_power_off; 47EXPORT_SYMBOL(pm_power_off); 48 49void 50cpu_idle(void) 51{ 52 set_thread_flag(TIF_POLLING_NRFLAG); 53 54 while (1) { 55 56 while (!need_resched()) 57 cpu_relax(); 58 schedule(); 59 } 60} 61 62 63struct halt_info { 64 int mode; 65 char *restart_cmd; 66}; 67 68static void 69common_shutdown_1(void *generic_ptr) 70{ 71 struct halt_info *how = (struct halt_info *)generic_ptr; 72 struct percpu_struct *cpup; 73 unsigned long *pflags, flags; 74 int cpuid = smp_processor_id(); 75 76 /* No point in taking interrupts anymore. */ 77 local_irq_disable(); 78 79 cpup = (struct percpu_struct *) 80 ((unsigned long)hwrpb + hwrpb->processor_offset 81 + hwrpb->processor_size * cpuid); 82 pflags = &cpup->flags; 83 flags = *pflags; 84 85 /* Clear reason to "default"; clear "bootstrap in progress". */ 86 flags &= ~0x00ff0001UL; 87 88#ifdef CONFIG_SMP 89 /* Secondaries halt here. */ 90 if (cpuid != boot_cpuid) { 91 flags |= 0x00040000UL; /* "remain halted" */ 92 *pflags = flags; 93 set_cpu_present(cpuid, false); 94 set_cpu_possible(cpuid, false); 95 halt(); 96 } 97#endif 98 99 if (how->mode == LINUX_REBOOT_CMD_RESTART) { 100 if (!how->restart_cmd) { 101 flags |= 0x00020000UL; /* "cold bootstrap" */ 102 } else { 103 /* For SRM, we could probably set environment 104 variables to get this to work. We'd have to 105 delay this until after srm_paging_stop unless 106 we ever got srm_fixup working. 107 108 At the moment, SRM will use the last boot device, 109 but the file and flags will be the defaults, when 110 doing a "warm" bootstrap. */ 111 flags |= 0x00030000UL; /* "warm bootstrap" */ 112 } 113 } else { 114 flags |= 0x00040000UL; /* "remain halted" */ 115 } 116 *pflags = flags; 117 118#ifdef CONFIG_SMP 119 /* Wait for the secondaries to halt. */ 120 set_cpu_present(boot_cpuid, false); 121 set_cpu_possible(boot_cpuid, false); 122 while (cpus_weight(cpu_present_map)) 123 barrier(); 124#endif 125 126 /* If booted from SRM, reset some of the original environment. */ 127 if (alpha_using_srm) { 128#ifdef CONFIG_DUMMY_CONSOLE 129 /* If we've gotten here after SysRq-b, leave interrupt 130 context before taking over the console. */ 131 if (in_interrupt()) 132 irq_exit(); 133 /* This has the effect of resetting the VGA video origin. */ 134 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 135#endif 136 pci_restore_srm_config(); 137 set_hae(srm_hae); 138 } 139 140 if (alpha_mv.kill_arch) 141 alpha_mv.kill_arch(how->mode); 142 143 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 144 /* Unfortunately, since MILO doesn't currently understand 145 the hwrpb bits above, we can't reliably halt the 146 processor and keep it halted. So just loop. */ 147 return; 148 } 149 150 if (alpha_using_srm) 151 srm_paging_stop(); 152 153 halt(); 154} 155 156static void 157common_shutdown(int mode, char *restart_cmd) 158{ 159 struct halt_info args; 160 args.mode = mode; 161 args.restart_cmd = restart_cmd; 162 on_each_cpu(common_shutdown_1, &args, 0); 163} 164 165void 166machine_restart(char *restart_cmd) 167{ 168 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 169} 170 171 172void 173machine_halt(void) 174{ 175 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 176} 177 178 179void 180machine_power_off(void) 181{ 182 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 183} 184 185 186/* Used by sysrq-p, among others. I don't believe r9-r15 are ever 187 saved in the context it's used. */ 188 189void 190show_regs(struct pt_regs *regs) 191{ 192 dik_show_regs(regs, NULL); 193} 194 195/* 196 * Re-start a thread when doing execve() 197 */ 198void 199start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 200{ 201 set_fs(USER_DS); 202 regs->pc = pc; 203 regs->ps = 8; 204 wrusp(sp); 205} 206EXPORT_SYMBOL(start_thread); 207 208/* 209 * Free current thread data structures etc.. 210 */ 211void 212exit_thread(void) 213{ 214} 215 216void 217flush_thread(void) 218{ 219 /* Arrange for each exec'ed process to start off with a clean slate 220 with respect to the FPU. This is all exceptions disabled. */ 221 current_thread_info()->ieee_state = 0; 222 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 223 224 /* Clean slate for TLS. */ 225 current_thread_info()->pcb.unique = 0; 226} 227 228void 229release_thread(struct task_struct *dead_task) 230{ 231} 232 233/* 234 * "alpha_clone()".. By the time we get here, the 235 * non-volatile registers have also been saved on the 236 * stack. We do some ugly pointer stuff here.. (see 237 * also copy_thread) 238 * 239 * Notice that "fork()" is implemented in terms of clone, 240 * with parameters (SIGCHLD, 0). 241 */ 242int 243alpha_clone(unsigned long clone_flags, unsigned long usp, 244 int __user *parent_tid, int __user *child_tid, 245 unsigned long tls_value, struct pt_regs *regs) 246{ 247 if (!usp) 248 usp = rdusp(); 249 250 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid); 251} 252 253int 254alpha_vfork(struct pt_regs *regs) 255{ 256 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), 257 regs, 0, NULL, NULL); 258} 259 260/* 261 * Copy an alpha thread.. 262 * 263 * Note the "stack_offset" stuff: when returning to kernel mode, we need 264 * to have some extra stack-space for the kernel stack that still exists 265 * after the "ret_from_fork". When returning to user mode, we only want 266 * the space needed by the syscall stack frame (ie "struct pt_regs"). 267 * Use the passed "regs" pointer to determine how much space we need 268 * for a kernel fork(). 269 */ 270 271int 272copy_thread(unsigned long clone_flags, unsigned long usp, 273 unsigned long unused, 274 struct task_struct * p, struct pt_regs * regs) 275{ 276 extern void ret_from_fork(void); 277 278 struct thread_info *childti = task_thread_info(p); 279 struct pt_regs * childregs; 280 struct switch_stack * childstack, *stack; 281 unsigned long stack_offset, settls; 282 283 stack_offset = PAGE_SIZE - sizeof(struct pt_regs); 284 if (!(regs->ps & 8)) 285 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs; 286 childregs = (struct pt_regs *) 287 (stack_offset + PAGE_SIZE + task_stack_page(p)); 288 289 *childregs = *regs; 290 settls = regs->r20; 291 childregs->r0 = 0; 292 childregs->r19 = 0; 293 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 294 regs->r20 = 0; 295 stack = ((struct switch_stack *) regs) - 1; 296 childstack = ((struct switch_stack *) childregs) - 1; 297 *childstack = *stack; 298 childstack->r26 = (unsigned long) ret_from_fork; 299 childti->pcb.usp = usp; 300 childti->pcb.ksp = (unsigned long) childstack; 301 childti->pcb.flags = 1; /* set FEN, clear everything else */ 302 303 /* Set a new TLS for the child thread? Peek back into the 304 syscall arguments that we saved on syscall entry. Oops, 305 except we'd have clobbered it with the parent/child set 306 of r20. Read the saved copy. */ 307 /* Note: if CLONE_SETTLS is not set, then we must inherit the 308 value from the parent, which will have been set by the block 309 copy in dup_task_struct. This is non-intuitive, but is 310 required for proper operation in the case of a threaded 311 application calling fork. */ 312 if (clone_flags & CLONE_SETTLS) 313 childti->pcb.unique = settls; 314 315 return 0; 316} 317 318/* 319 * Fill in the user structure for a ELF core dump. 320 */ 321void 322dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 323{ 324 /* switch stack follows right below pt_regs: */ 325 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 326 327 dest[ 0] = pt->r0; 328 dest[ 1] = pt->r1; 329 dest[ 2] = pt->r2; 330 dest[ 3] = pt->r3; 331 dest[ 4] = pt->r4; 332 dest[ 5] = pt->r5; 333 dest[ 6] = pt->r6; 334 dest[ 7] = pt->r7; 335 dest[ 8] = pt->r8; 336 dest[ 9] = sw->r9; 337 dest[10] = sw->r10; 338 dest[11] = sw->r11; 339 dest[12] = sw->r12; 340 dest[13] = sw->r13; 341 dest[14] = sw->r14; 342 dest[15] = sw->r15; 343 dest[16] = pt->r16; 344 dest[17] = pt->r17; 345 dest[18] = pt->r18; 346 dest[19] = pt->r19; 347 dest[20] = pt->r20; 348 dest[21] = pt->r21; 349 dest[22] = pt->r22; 350 dest[23] = pt->r23; 351 dest[24] = pt->r24; 352 dest[25] = pt->r25; 353 dest[26] = pt->r26; 354 dest[27] = pt->r27; 355 dest[28] = pt->r28; 356 dest[29] = pt->gp; 357 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 358 dest[31] = pt->pc; 359 360 /* Once upon a time this was the PS value. Which is stupid 361 since that is always 8 for usermode. Usurped for the more 362 useful value of the thread's UNIQUE field. */ 363 dest[32] = ti->pcb.unique; 364} 365EXPORT_SYMBOL(dump_elf_thread); 366 367int 368dump_elf_task(elf_greg_t *dest, struct task_struct *task) 369{ 370 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 371 return 1; 372} 373EXPORT_SYMBOL(dump_elf_task); 374 375int 376dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 377{ 378 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 379 memcpy(dest, sw->fp, 32 * 8); 380 return 1; 381} 382EXPORT_SYMBOL(dump_elf_task_fp); 383 384/* 385 * sys_execve() executes a new program. 386 */ 387asmlinkage int 388do_sys_execve(const char __user *ufilename, 389 const char __user *const __user *argv, 390 const char __user *const __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); 401out: 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 419unsigned long 420thread_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 434unsigned long 435get_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