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 */ 46 void (*pm_power_off)(void) = machine_power_off; 47 EXPORT_SYMBOL(pm_power_off); 48 49 #ifdef CONFIG_ALPHA_WTINT 50 /* 51 * Sleep the CPU. 52 * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts. 53 */ 54 void arch_cpu_idle(void) 55 { 56 wtint(0); 57 local_irq_enable(); 58 } 59 60 void arch_cpu_idle_dead(void) 61 { 62 wtint(INT_MAX); 63 } 64 #endif /* ALPHA_WTINT */ 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 (cpumask_weight(cpu_present_mask)) 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 console_lock(); 138 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 139 console_unlock(); 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 } 160 161 static void 162 common_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 } 169 170 void 171 machine_restart(char *restart_cmd) 172 { 173 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 174 } 175 176 177 void 178 machine_halt(void) 179 { 180 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 181 } 182 183 184 void 185 machine_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. */ 193 194 void 195 show_regs(struct pt_regs *regs) 196 { 197 show_regs_print_info(KERN_DEFAULT); 198 dik_show_regs(regs, NULL); 199 } 200 201 /* 202 * Re-start a thread when doing execve() 203 */ 204 void 205 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 206 { 207 regs->pc = pc; 208 regs->ps = 8; 209 wrusp(sp); 210 } 211 EXPORT_SYMBOL(start_thread); 212 213 void 214 flush_thread(void) 215 { 216 /* Arrange for each exec'ed process to start off with a clean slate 217 with respect to the FPU. This is all exceptions disabled. */ 218 current_thread_info()->ieee_state = 0; 219 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 220 221 /* Clean slate for TLS. */ 222 current_thread_info()->pcb.unique = 0; 223 } 224 225 void 226 release_thread(struct task_struct *dead_task) 227 { 228 } 229 230 /* 231 * Copy architecture-specific thread state 232 */ 233 int 234 copy_thread(unsigned long clone_flags, unsigned long usp, 235 unsigned long kthread_arg, 236 struct task_struct *p) 237 { 238 extern void ret_from_fork(void); 239 extern void ret_from_kernel_thread(void); 240 241 struct thread_info *childti = task_thread_info(p); 242 struct pt_regs *childregs = task_pt_regs(p); 243 struct pt_regs *regs = current_pt_regs(); 244 struct switch_stack *childstack, *stack; 245 246 childstack = ((struct switch_stack *) childregs) - 1; 247 childti->pcb.ksp = (unsigned long) childstack; 248 childti->pcb.flags = 1; /* set FEN, clear everything else */ 249 250 if (unlikely(p->flags & PF_KTHREAD)) { 251 /* kernel thread */ 252 memset(childstack, 0, 253 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 254 childstack->r26 = (unsigned long) ret_from_kernel_thread; 255 childstack->r9 = usp; /* function */ 256 childstack->r10 = kthread_arg; 257 childregs->hae = alpha_mv.hae_cache, 258 childti->pcb.usp = 0; 259 return 0; 260 } 261 /* Note: if CLONE_SETTLS is not set, then we must inherit the 262 value from the parent, which will have been set by the block 263 copy in dup_task_struct. This is non-intuitive, but is 264 required for proper operation in the case of a threaded 265 application calling fork. */ 266 if (clone_flags & CLONE_SETTLS) 267 childti->pcb.unique = regs->r20; 268 childti->pcb.usp = usp ?: rdusp(); 269 *childregs = *regs; 270 childregs->r0 = 0; 271 childregs->r19 = 0; 272 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 273 regs->r20 = 0; 274 stack = ((struct switch_stack *) regs) - 1; 275 *childstack = *stack; 276 childstack->r26 = (unsigned long) ret_from_fork; 277 return 0; 278 } 279 280 /* 281 * Fill in the user structure for a ELF core dump. 282 */ 283 void 284 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 285 { 286 /* switch stack follows right below pt_regs: */ 287 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 288 289 dest[ 0] = pt->r0; 290 dest[ 1] = pt->r1; 291 dest[ 2] = pt->r2; 292 dest[ 3] = pt->r3; 293 dest[ 4] = pt->r4; 294 dest[ 5] = pt->r5; 295 dest[ 6] = pt->r6; 296 dest[ 7] = pt->r7; 297 dest[ 8] = pt->r8; 298 dest[ 9] = sw->r9; 299 dest[10] = sw->r10; 300 dest[11] = sw->r11; 301 dest[12] = sw->r12; 302 dest[13] = sw->r13; 303 dest[14] = sw->r14; 304 dest[15] = sw->r15; 305 dest[16] = pt->r16; 306 dest[17] = pt->r17; 307 dest[18] = pt->r18; 308 dest[19] = pt->r19; 309 dest[20] = pt->r20; 310 dest[21] = pt->r21; 311 dest[22] = pt->r22; 312 dest[23] = pt->r23; 313 dest[24] = pt->r24; 314 dest[25] = pt->r25; 315 dest[26] = pt->r26; 316 dest[27] = pt->r27; 317 dest[28] = pt->r28; 318 dest[29] = pt->gp; 319 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 320 dest[31] = pt->pc; 321 322 /* Once upon a time this was the PS value. Which is stupid 323 since that is always 8 for usermode. Usurped for the more 324 useful value of the thread's UNIQUE field. */ 325 dest[32] = ti->pcb.unique; 326 } 327 EXPORT_SYMBOL(dump_elf_thread); 328 329 int 330 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 331 { 332 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 333 return 1; 334 } 335 EXPORT_SYMBOL(dump_elf_task); 336 337 int 338 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 339 { 340 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 341 memcpy(dest, sw->fp, 32 * 8); 342 return 1; 343 } 344 EXPORT_SYMBOL(dump_elf_task_fp); 345 346 /* 347 * Return saved PC of a blocked thread. This assumes the frame 348 * pointer is the 6th saved long on the kernel stack and that the 349 * saved return address is the first long in the frame. This all 350 * holds provided the thread blocked through a call to schedule() ($15 351 * is the frame pointer in schedule() and $15 is saved at offset 48 by 352 * entry.S:do_switch_stack). 353 * 354 * Under heavy swap load I've seen this lose in an ugly way. So do 355 * some extra sanity checking on the ranges we expect these pointers 356 * to be in so that we can fail gracefully. This is just for ps after 357 * all. -- r~ 358 */ 359 360 unsigned long 361 thread_saved_pc(struct task_struct *t) 362 { 363 unsigned long base = (unsigned long)task_stack_page(t); 364 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 365 366 if (sp > base && sp+6*8 < base + 16*1024) { 367 fp = ((unsigned long*)sp)[6]; 368 if (fp > sp && fp < base + 16*1024) 369 return *(unsigned long *)fp; 370 } 371 372 return 0; 373 } 374 375 unsigned long 376 get_wchan(struct task_struct *p) 377 { 378 unsigned long schedule_frame; 379 unsigned long pc; 380 if (!p || p == current || p->state == TASK_RUNNING) 381 return 0; 382 /* 383 * This one depends on the frame size of schedule(). Do a 384 * "disass schedule" in gdb to find the frame size. Also, the 385 * code assumes that sleep_on() follows immediately after 386 * interruptible_sleep_on() and that add_timer() follows 387 * immediately after interruptible_sleep(). Ugly, isn't it? 388 * Maybe adding a wchan field to task_struct would be better, 389 * after all... 390 */ 391 392 pc = thread_saved_pc(p); 393 if (in_sched_functions(pc)) { 394 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 395 return ((unsigned long *)schedule_frame)[12]; 396 } 397 return pc; 398 } 399