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 struct halt_info { 50 int mode; 51 char *restart_cmd; 52 }; 53 54 static void 55 common_shutdown_1(void *generic_ptr) 56 { 57 struct halt_info *how = (struct halt_info *)generic_ptr; 58 struct percpu_struct *cpup; 59 unsigned long *pflags, flags; 60 int cpuid = smp_processor_id(); 61 62 /* No point in taking interrupts anymore. */ 63 local_irq_disable(); 64 65 cpup = (struct percpu_struct *) 66 ((unsigned long)hwrpb + hwrpb->processor_offset 67 + hwrpb->processor_size * cpuid); 68 pflags = &cpup->flags; 69 flags = *pflags; 70 71 /* Clear reason to "default"; clear "bootstrap in progress". */ 72 flags &= ~0x00ff0001UL; 73 74 #ifdef CONFIG_SMP 75 /* Secondaries halt here. */ 76 if (cpuid != boot_cpuid) { 77 flags |= 0x00040000UL; /* "remain halted" */ 78 *pflags = flags; 79 set_cpu_present(cpuid, false); 80 set_cpu_possible(cpuid, false); 81 halt(); 82 } 83 #endif 84 85 if (how->mode == LINUX_REBOOT_CMD_RESTART) { 86 if (!how->restart_cmd) { 87 flags |= 0x00020000UL; /* "cold bootstrap" */ 88 } else { 89 /* For SRM, we could probably set environment 90 variables to get this to work. We'd have to 91 delay this until after srm_paging_stop unless 92 we ever got srm_fixup working. 93 94 At the moment, SRM will use the last boot device, 95 but the file and flags will be the defaults, when 96 doing a "warm" bootstrap. */ 97 flags |= 0x00030000UL; /* "warm bootstrap" */ 98 } 99 } else { 100 flags |= 0x00040000UL; /* "remain halted" */ 101 } 102 *pflags = flags; 103 104 #ifdef CONFIG_SMP 105 /* Wait for the secondaries to halt. */ 106 set_cpu_present(boot_cpuid, false); 107 set_cpu_possible(boot_cpuid, false); 108 while (cpumask_weight(cpu_present_mask)) 109 barrier(); 110 #endif 111 112 /* If booted from SRM, reset some of the original environment. */ 113 if (alpha_using_srm) { 114 #ifdef CONFIG_DUMMY_CONSOLE 115 /* If we've gotten here after SysRq-b, leave interrupt 116 context before taking over the console. */ 117 if (in_interrupt()) 118 irq_exit(); 119 /* This has the effect of resetting the VGA video origin. */ 120 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 121 #endif 122 pci_restore_srm_config(); 123 set_hae(srm_hae); 124 } 125 126 if (alpha_mv.kill_arch) 127 alpha_mv.kill_arch(how->mode); 128 129 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 130 /* Unfortunately, since MILO doesn't currently understand 131 the hwrpb bits above, we can't reliably halt the 132 processor and keep it halted. So just loop. */ 133 return; 134 } 135 136 if (alpha_using_srm) 137 srm_paging_stop(); 138 139 halt(); 140 } 141 142 static void 143 common_shutdown(int mode, char *restart_cmd) 144 { 145 struct halt_info args; 146 args.mode = mode; 147 args.restart_cmd = restart_cmd; 148 on_each_cpu(common_shutdown_1, &args, 0); 149 } 150 151 void 152 machine_restart(char *restart_cmd) 153 { 154 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 155 } 156 157 158 void 159 machine_halt(void) 160 { 161 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 162 } 163 164 165 void 166 machine_power_off(void) 167 { 168 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 169 } 170 171 172 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 173 saved in the context it's used. */ 174 175 void 176 show_regs(struct pt_regs *regs) 177 { 178 show_regs_print_info(KERN_DEFAULT); 179 dik_show_regs(regs, NULL); 180 } 181 182 /* 183 * Re-start a thread when doing execve() 184 */ 185 void 186 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 187 { 188 regs->pc = pc; 189 regs->ps = 8; 190 wrusp(sp); 191 } 192 EXPORT_SYMBOL(start_thread); 193 194 /* 195 * Free current thread data structures etc.. 196 */ 197 void 198 exit_thread(void) 199 { 200 } 201 202 void 203 flush_thread(void) 204 { 205 /* Arrange for each exec'ed process to start off with a clean slate 206 with respect to the FPU. This is all exceptions disabled. */ 207 current_thread_info()->ieee_state = 0; 208 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 209 210 /* Clean slate for TLS. */ 211 current_thread_info()->pcb.unique = 0; 212 } 213 214 void 215 release_thread(struct task_struct *dead_task) 216 { 217 } 218 219 /* 220 * Copy an alpha thread.. 221 */ 222 223 int 224 copy_thread(unsigned long clone_flags, unsigned long usp, 225 unsigned long arg, 226 struct task_struct *p) 227 { 228 extern void ret_from_fork(void); 229 extern void ret_from_kernel_thread(void); 230 231 struct thread_info *childti = task_thread_info(p); 232 struct pt_regs *childregs = task_pt_regs(p); 233 struct pt_regs *regs = current_pt_regs(); 234 struct switch_stack *childstack, *stack; 235 236 childstack = ((struct switch_stack *) childregs) - 1; 237 childti->pcb.ksp = (unsigned long) childstack; 238 childti->pcb.flags = 1; /* set FEN, clear everything else */ 239 240 if (unlikely(p->flags & PF_KTHREAD)) { 241 /* kernel thread */ 242 memset(childstack, 0, 243 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 244 childstack->r26 = (unsigned long) ret_from_kernel_thread; 245 childstack->r9 = usp; /* function */ 246 childstack->r10 = arg; 247 childregs->hae = alpha_mv.hae_cache, 248 childti->pcb.usp = 0; 249 return 0; 250 } 251 /* Note: if CLONE_SETTLS is not set, then we must inherit the 252 value from the parent, which will have been set by the block 253 copy in dup_task_struct. This is non-intuitive, but is 254 required for proper operation in the case of a threaded 255 application calling fork. */ 256 if (clone_flags & CLONE_SETTLS) 257 childti->pcb.unique = regs->r20; 258 childti->pcb.usp = usp ?: rdusp(); 259 *childregs = *regs; 260 childregs->r0 = 0; 261 childregs->r19 = 0; 262 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 263 regs->r20 = 0; 264 stack = ((struct switch_stack *) regs) - 1; 265 *childstack = *stack; 266 childstack->r26 = (unsigned long) ret_from_fork; 267 return 0; 268 } 269 270 /* 271 * Fill in the user structure for a ELF core dump. 272 */ 273 void 274 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 275 { 276 /* switch stack follows right below pt_regs: */ 277 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 278 279 dest[ 0] = pt->r0; 280 dest[ 1] = pt->r1; 281 dest[ 2] = pt->r2; 282 dest[ 3] = pt->r3; 283 dest[ 4] = pt->r4; 284 dest[ 5] = pt->r5; 285 dest[ 6] = pt->r6; 286 dest[ 7] = pt->r7; 287 dest[ 8] = pt->r8; 288 dest[ 9] = sw->r9; 289 dest[10] = sw->r10; 290 dest[11] = sw->r11; 291 dest[12] = sw->r12; 292 dest[13] = sw->r13; 293 dest[14] = sw->r14; 294 dest[15] = sw->r15; 295 dest[16] = pt->r16; 296 dest[17] = pt->r17; 297 dest[18] = pt->r18; 298 dest[19] = pt->r19; 299 dest[20] = pt->r20; 300 dest[21] = pt->r21; 301 dest[22] = pt->r22; 302 dest[23] = pt->r23; 303 dest[24] = pt->r24; 304 dest[25] = pt->r25; 305 dest[26] = pt->r26; 306 dest[27] = pt->r27; 307 dest[28] = pt->r28; 308 dest[29] = pt->gp; 309 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 310 dest[31] = pt->pc; 311 312 /* Once upon a time this was the PS value. Which is stupid 313 since that is always 8 for usermode. Usurped for the more 314 useful value of the thread's UNIQUE field. */ 315 dest[32] = ti->pcb.unique; 316 } 317 EXPORT_SYMBOL(dump_elf_thread); 318 319 int 320 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 321 { 322 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 323 return 1; 324 } 325 EXPORT_SYMBOL(dump_elf_task); 326 327 int 328 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 329 { 330 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 331 memcpy(dest, sw->fp, 32 * 8); 332 return 1; 333 } 334 EXPORT_SYMBOL(dump_elf_task_fp); 335 336 /* 337 * Return saved PC of a blocked thread. This assumes the frame 338 * pointer is the 6th saved long on the kernel stack and that the 339 * saved return address is the first long in the frame. This all 340 * holds provided the thread blocked through a call to schedule() ($15 341 * is the frame pointer in schedule() and $15 is saved at offset 48 by 342 * entry.S:do_switch_stack). 343 * 344 * Under heavy swap load I've seen this lose in an ugly way. So do 345 * some extra sanity checking on the ranges we expect these pointers 346 * to be in so that we can fail gracefully. This is just for ps after 347 * all. -- r~ 348 */ 349 350 unsigned long 351 thread_saved_pc(struct task_struct *t) 352 { 353 unsigned long base = (unsigned long)task_stack_page(t); 354 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 355 356 if (sp > base && sp+6*8 < base + 16*1024) { 357 fp = ((unsigned long*)sp)[6]; 358 if (fp > sp && fp < base + 16*1024) 359 return *(unsigned long *)fp; 360 } 361 362 return 0; 363 } 364 365 unsigned long 366 get_wchan(struct task_struct *p) 367 { 368 unsigned long schedule_frame; 369 unsigned long pc; 370 if (!p || p == current || p->state == TASK_RUNNING) 371 return 0; 372 /* 373 * This one depends on the frame size of schedule(). Do a 374 * "disass schedule" in gdb to find the frame size. Also, the 375 * code assumes that sleep_on() follows immediately after 376 * interruptible_sleep_on() and that add_timer() follows 377 * immediately after interruptible_sleep(). Ugly, isn't it? 378 * Maybe adding a wchan field to task_struct would be better, 379 * after all... 380 */ 381 382 pc = thread_saved_pc(p); 383 if (in_sched_functions(pc)) { 384 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 385 return ((unsigned long *)schedule_frame)[12]; 386 } 387 return pc; 388 } 389