process.c revision 4c94cada48f7c660eca582be6032427a5e367117
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 */ 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 /* 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 68struct halt_info { 69 int mode; 70 char *restart_cmd; 71}; 72 73static void 74common_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 161static void 162common_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 170void 171machine_restart(char *restart_cmd) 172{ 173 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 174} 175 176 177void 178machine_halt(void) 179{ 180 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 181} 182 183 184void 185machine_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 194void 195show_regs(struct pt_regs *regs) 196{ 197 dik_show_regs(regs, NULL); 198} 199 200/* 201 * Re-start a thread when doing execve() 202 */ 203void 204start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 205{ 206 regs->pc = pc; 207 regs->ps = 8; 208 wrusp(sp); 209} 210EXPORT_SYMBOL(start_thread); 211 212/* 213 * Free current thread data structures etc.. 214 */ 215void 216exit_thread(void) 217{ 218} 219 220void 221flush_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 232void 233release_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 */ 246int 247alpha_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 257int 258alpha_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 * Note the "stack_offset" stuff: when returning to kernel mode, we need 268 * to have some extra stack-space for the kernel stack that still exists 269 * after the "ret_from_fork". When returning to user mode, we only want 270 * the space needed by the syscall stack frame (ie "struct pt_regs"). 271 * Use the passed "regs" pointer to determine how much space we need 272 * for a kernel fork(). 273 */ 274 275int 276copy_thread(unsigned long clone_flags, unsigned long usp, 277 unsigned long unused, 278 struct task_struct * p, struct pt_regs * regs) 279{ 280 extern void ret_from_fork(void); 281 282 struct thread_info *childti = task_thread_info(p); 283 struct pt_regs * childregs; 284 struct switch_stack * childstack, *stack; 285 unsigned long stack_offset, settls; 286 287 stack_offset = PAGE_SIZE - sizeof(struct pt_regs); 288 if (!(regs->ps & 8)) 289 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs; 290 childregs = (struct pt_regs *) 291 (stack_offset + PAGE_SIZE + task_stack_page(p)); 292 293 *childregs = *regs; 294 settls = regs->r20; 295 childregs->r0 = 0; 296 childregs->r19 = 0; 297 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 298 regs->r20 = 0; 299 stack = ((struct switch_stack *) regs) - 1; 300 childstack = ((struct switch_stack *) childregs) - 1; 301 *childstack = *stack; 302 childstack->r26 = (unsigned long) ret_from_fork; 303 childti->pcb.usp = usp; 304 childti->pcb.ksp = (unsigned long) childstack; 305 childti->pcb.flags = 1; /* set FEN, clear everything else */ 306 307 /* Set a new TLS for the child thread? Peek back into the 308 syscall arguments that we saved on syscall entry. Oops, 309 except we'd have clobbered it with the parent/child set 310 of r20. Read the saved copy. */ 311 /* Note: if CLONE_SETTLS is not set, then we must inherit the 312 value from the parent, which will have been set by the block 313 copy in dup_task_struct. This is non-intuitive, but is 314 required for proper operation in the case of a threaded 315 application calling fork. */ 316 if (clone_flags & CLONE_SETTLS) 317 childti->pcb.unique = settls; 318 319 return 0; 320} 321 322/* 323 * Fill in the user structure for a ELF core dump. 324 */ 325void 326dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 327{ 328 /* switch stack follows right below pt_regs: */ 329 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 330 331 dest[ 0] = pt->r0; 332 dest[ 1] = pt->r1; 333 dest[ 2] = pt->r2; 334 dest[ 3] = pt->r3; 335 dest[ 4] = pt->r4; 336 dest[ 5] = pt->r5; 337 dest[ 6] = pt->r6; 338 dest[ 7] = pt->r7; 339 dest[ 8] = pt->r8; 340 dest[ 9] = sw->r9; 341 dest[10] = sw->r10; 342 dest[11] = sw->r11; 343 dest[12] = sw->r12; 344 dest[13] = sw->r13; 345 dest[14] = sw->r14; 346 dest[15] = sw->r15; 347 dest[16] = pt->r16; 348 dest[17] = pt->r17; 349 dest[18] = pt->r18; 350 dest[19] = pt->r19; 351 dest[20] = pt->r20; 352 dest[21] = pt->r21; 353 dest[22] = pt->r22; 354 dest[23] = pt->r23; 355 dest[24] = pt->r24; 356 dest[25] = pt->r25; 357 dest[26] = pt->r26; 358 dest[27] = pt->r27; 359 dest[28] = pt->r28; 360 dest[29] = pt->gp; 361 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 362 dest[31] = pt->pc; 363 364 /* Once upon a time this was the PS value. Which is stupid 365 since that is always 8 for usermode. Usurped for the more 366 useful value of the thread's UNIQUE field. */ 367 dest[32] = ti->pcb.unique; 368} 369EXPORT_SYMBOL(dump_elf_thread); 370 371int 372dump_elf_task(elf_greg_t *dest, struct task_struct *task) 373{ 374 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 375 return 1; 376} 377EXPORT_SYMBOL(dump_elf_task); 378 379int 380dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 381{ 382 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 383 memcpy(dest, sw->fp, 32 * 8); 384 return 1; 385} 386EXPORT_SYMBOL(dump_elf_task_fp); 387 388/* 389 * sys_execve() executes a new program. 390 */ 391asmlinkage int 392do_sys_execve(const char __user *ufilename, 393 const char __user *const __user *argv, 394 const char __user *const __user *envp, struct pt_regs *regs) 395{ 396 int error; 397 char *filename; 398 399 filename = getname(ufilename); 400 error = PTR_ERR(filename); 401 if (IS_ERR(filename)) 402 goto out; 403 error = do_execve(filename, argv, envp, regs); 404 putname(filename); 405out: 406 return error; 407} 408 409/* 410 * Return saved PC of a blocked thread. This assumes the frame 411 * pointer is the 6th saved long on the kernel stack and that the 412 * saved return address is the first long in the frame. This all 413 * holds provided the thread blocked through a call to schedule() ($15 414 * is the frame pointer in schedule() and $15 is saved at offset 48 by 415 * entry.S:do_switch_stack). 416 * 417 * Under heavy swap load I've seen this lose in an ugly way. So do 418 * some extra sanity checking on the ranges we expect these pointers 419 * to be in so that we can fail gracefully. This is just for ps after 420 * all. -- r~ 421 */ 422 423unsigned long 424thread_saved_pc(struct task_struct *t) 425{ 426 unsigned long base = (unsigned long)task_stack_page(t); 427 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 428 429 if (sp > base && sp+6*8 < base + 16*1024) { 430 fp = ((unsigned long*)sp)[6]; 431 if (fp > sp && fp < base + 16*1024) 432 return *(unsigned long *)fp; 433 } 434 435 return 0; 436} 437 438unsigned long 439get_wchan(struct task_struct *p) 440{ 441 unsigned long schedule_frame; 442 unsigned long pc; 443 if (!p || p == current || p->state == TASK_RUNNING) 444 return 0; 445 /* 446 * This one depends on the frame size of schedule(). Do a 447 * "disass schedule" in gdb to find the frame size. Also, the 448 * code assumes that sleep_on() follows immediately after 449 * interruptible_sleep_on() and that add_timer() follows 450 * immediately after interruptible_sleep(). Ugly, isn't it? 451 * Maybe adding a wchan field to task_struct would be better, 452 * after all... 453 */ 454 455 pc = thread_saved_pc(p); 456 if (in_sched_functions(pc)) { 457 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 458 return ((unsigned long *)schedule_frame)[12]; 459 } 460 return pc; 461} 462 463int kernel_execve(const char *path, const char *const argv[], const char *const envp[]) 464{ 465 /* Avoid the HAE being gratuitously wrong, which would cause us 466 to do the whole turn off interrupts thing and restore it. */ 467 struct pt_regs regs = {.hae = alpha_mv.hae_cache}; 468 int err = do_execve(path, argv, envp, ®s); 469 if (!err) { 470 struct pt_regs *p = current_pt_regs(); 471 /* copy regs to normal position and off to userland we go... */ 472 *p = regs; 473 __asm__ __volatile__ ( 474 "mov %0, $sp;" 475 "br $31, ret_from_sys_call" 476 : : "r"(p)); 477 } 478 return err; 479} 480EXPORT_SYMBOL(kernel_execve); 481