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 console_lock(); 121 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1); 122 console_unlock(); 123 #endif 124 pci_restore_srm_config(); 125 set_hae(srm_hae); 126 } 127 128 if (alpha_mv.kill_arch) 129 alpha_mv.kill_arch(how->mode); 130 131 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) { 132 /* Unfortunately, since MILO doesn't currently understand 133 the hwrpb bits above, we can't reliably halt the 134 processor and keep it halted. So just loop. */ 135 return; 136 } 137 138 if (alpha_using_srm) 139 srm_paging_stop(); 140 141 halt(); 142 } 143 144 static void 145 common_shutdown(int mode, char *restart_cmd) 146 { 147 struct halt_info args; 148 args.mode = mode; 149 args.restart_cmd = restart_cmd; 150 on_each_cpu(common_shutdown_1, &args, 0); 151 } 152 153 void 154 machine_restart(char *restart_cmd) 155 { 156 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); 157 } 158 159 160 void 161 machine_halt(void) 162 { 163 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); 164 } 165 166 167 void 168 machine_power_off(void) 169 { 170 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL); 171 } 172 173 174 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever 175 saved in the context it's used. */ 176 177 void 178 show_regs(struct pt_regs *regs) 179 { 180 show_regs_print_info(KERN_DEFAULT); 181 dik_show_regs(regs, NULL); 182 } 183 184 /* 185 * Re-start a thread when doing execve() 186 */ 187 void 188 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 189 { 190 regs->pc = pc; 191 regs->ps = 8; 192 wrusp(sp); 193 } 194 EXPORT_SYMBOL(start_thread); 195 196 /* 197 * Free current thread data structures etc.. 198 */ 199 void 200 exit_thread(void) 201 { 202 } 203 204 void 205 flush_thread(void) 206 { 207 /* Arrange for each exec'ed process to start off with a clean slate 208 with respect to the FPU. This is all exceptions disabled. */ 209 current_thread_info()->ieee_state = 0; 210 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 211 212 /* Clean slate for TLS. */ 213 current_thread_info()->pcb.unique = 0; 214 } 215 216 void 217 release_thread(struct task_struct *dead_task) 218 { 219 } 220 221 /* 222 * Copy an alpha thread.. 223 */ 224 225 int 226 copy_thread(unsigned long clone_flags, unsigned long usp, 227 unsigned long arg, 228 struct task_struct *p) 229 { 230 extern void ret_from_fork(void); 231 extern void ret_from_kernel_thread(void); 232 233 struct thread_info *childti = task_thread_info(p); 234 struct pt_regs *childregs = task_pt_regs(p); 235 struct pt_regs *regs = current_pt_regs(); 236 struct switch_stack *childstack, *stack; 237 238 childstack = ((struct switch_stack *) childregs) - 1; 239 childti->pcb.ksp = (unsigned long) childstack; 240 childti->pcb.flags = 1; /* set FEN, clear everything else */ 241 242 if (unlikely(p->flags & PF_KTHREAD)) { 243 /* kernel thread */ 244 memset(childstack, 0, 245 sizeof(struct switch_stack) + sizeof(struct pt_regs)); 246 childstack->r26 = (unsigned long) ret_from_kernel_thread; 247 childstack->r9 = usp; /* function */ 248 childstack->r10 = arg; 249 childregs->hae = alpha_mv.hae_cache, 250 childti->pcb.usp = 0; 251 return 0; 252 } 253 /* Note: if CLONE_SETTLS is not set, then we must inherit the 254 value from the parent, which will have been set by the block 255 copy in dup_task_struct. This is non-intuitive, but is 256 required for proper operation in the case of a threaded 257 application calling fork. */ 258 if (clone_flags & CLONE_SETTLS) 259 childti->pcb.unique = regs->r20; 260 childti->pcb.usp = usp ?: rdusp(); 261 *childregs = *regs; 262 childregs->r0 = 0; 263 childregs->r19 = 0; 264 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ 265 regs->r20 = 0; 266 stack = ((struct switch_stack *) regs) - 1; 267 *childstack = *stack; 268 childstack->r26 = (unsigned long) ret_from_fork; 269 return 0; 270 } 271 272 /* 273 * Fill in the user structure for a ELF core dump. 274 */ 275 void 276 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti) 277 { 278 /* switch stack follows right below pt_regs: */ 279 struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 280 281 dest[ 0] = pt->r0; 282 dest[ 1] = pt->r1; 283 dest[ 2] = pt->r2; 284 dest[ 3] = pt->r3; 285 dest[ 4] = pt->r4; 286 dest[ 5] = pt->r5; 287 dest[ 6] = pt->r6; 288 dest[ 7] = pt->r7; 289 dest[ 8] = pt->r8; 290 dest[ 9] = sw->r9; 291 dest[10] = sw->r10; 292 dest[11] = sw->r11; 293 dest[12] = sw->r12; 294 dest[13] = sw->r13; 295 dest[14] = sw->r14; 296 dest[15] = sw->r15; 297 dest[16] = pt->r16; 298 dest[17] = pt->r17; 299 dest[18] = pt->r18; 300 dest[19] = pt->r19; 301 dest[20] = pt->r20; 302 dest[21] = pt->r21; 303 dest[22] = pt->r22; 304 dest[23] = pt->r23; 305 dest[24] = pt->r24; 306 dest[25] = pt->r25; 307 dest[26] = pt->r26; 308 dest[27] = pt->r27; 309 dest[28] = pt->r28; 310 dest[29] = pt->gp; 311 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp; 312 dest[31] = pt->pc; 313 314 /* Once upon a time this was the PS value. Which is stupid 315 since that is always 8 for usermode. Usurped for the more 316 useful value of the thread's UNIQUE field. */ 317 dest[32] = ti->pcb.unique; 318 } 319 EXPORT_SYMBOL(dump_elf_thread); 320 321 int 322 dump_elf_task(elf_greg_t *dest, struct task_struct *task) 323 { 324 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task)); 325 return 1; 326 } 327 EXPORT_SYMBOL(dump_elf_task); 328 329 int 330 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task) 331 { 332 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1; 333 memcpy(dest, sw->fp, 32 * 8); 334 return 1; 335 } 336 EXPORT_SYMBOL(dump_elf_task_fp); 337 338 /* 339 * Return saved PC of a blocked thread. This assumes the frame 340 * pointer is the 6th saved long on the kernel stack and that the 341 * saved return address is the first long in the frame. This all 342 * holds provided the thread blocked through a call to schedule() ($15 343 * is the frame pointer in schedule() and $15 is saved at offset 48 by 344 * entry.S:do_switch_stack). 345 * 346 * Under heavy swap load I've seen this lose in an ugly way. So do 347 * some extra sanity checking on the ranges we expect these pointers 348 * to be in so that we can fail gracefully. This is just for ps after 349 * all. -- r~ 350 */ 351 352 unsigned long 353 thread_saved_pc(struct task_struct *t) 354 { 355 unsigned long base = (unsigned long)task_stack_page(t); 356 unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 357 358 if (sp > base && sp+6*8 < base + 16*1024) { 359 fp = ((unsigned long*)sp)[6]; 360 if (fp > sp && fp < base + 16*1024) 361 return *(unsigned long *)fp; 362 } 363 364 return 0; 365 } 366 367 unsigned long 368 get_wchan(struct task_struct *p) 369 { 370 unsigned long schedule_frame; 371 unsigned long pc; 372 if (!p || p == current || p->state == TASK_RUNNING) 373 return 0; 374 /* 375 * This one depends on the frame size of schedule(). Do a 376 * "disass schedule" in gdb to find the frame size. Also, the 377 * code assumes that sleep_on() follows immediately after 378 * interruptible_sleep_on() and that add_timer() follows 379 * immediately after interruptible_sleep(). Ugly, isn't it? 380 * Maybe adding a wchan field to task_struct would be better, 381 * after all... 382 */ 383 384 pc = thread_saved_pc(p); 385 if (in_sched_functions(pc)) { 386 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6]; 387 return ((unsigned long *)schedule_frame)[12]; 388 } 389 return pc; 390 } 391