arch/alpha/kernel/process.c

   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 void
  50 cpu_idle(void)
  51 {
  52         current_thread_info()->status |= TS_POLLING;
  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
  68 struct halt_info {
  69         int mode;
  70         char *restart_cmd;
  71 };
  72
  73 static void
  74 common_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
 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         dik_show_regs(regs, NULL);
 198 }
 199
 200 /*
 201  * Re-start a thread when doing execve()
 202  */
 203 void
 204 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 205 {
 206         regs->pc = pc;
 207         regs->ps = 8;
 208         wrusp(sp);
 209 }
 210 EXPORT_SYMBOL(start_thread);
 211
 212 /*
 213  * Free current thread data structures etc..
 214  */
 215 void
 216 exit_thread(void)
 217 {
 218 }
 219
 220 void
 221 flush_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
 232 void
 233 release_thread(struct task_struct *dead_task)
 234 {
 235 }
 236
 237 /*
 238  * Copy an alpha thread..
 239  */
 240
 241 int
 242 copy_thread(unsigned long clone_flags, unsigned long usp,
 243             unsigned long arg,
 244             struct task_struct *p)
 245 {
 246         extern void ret_from_fork(void);
 247         extern void ret_from_kernel_thread(void);
 248
 249         struct thread_info *childti = task_thread_info(p);
 250         struct pt_regs *childregs = task_pt_regs(p);
 251         struct pt_regs *regs = current_pt_regs();
 252         struct switch_stack *childstack, *stack;
 253
 254         childstack = ((struct switch_stack *) childregs) - 1;
 255         childti->pcb.ksp = (unsigned long) childstack;
 256         childti->pcb.flags = 1; /* set FEN, clear everything else */
 257
 258         if (unlikely(p->flags & PF_KTHREAD)) {
 259                 /* kernel thread */
 260                 memset(childstack, 0,
 261                         sizeof(struct switch_stack) + sizeof(struct pt_regs));
 262                 childstack->r26 = (unsigned long) ret_from_kernel_thread;
 263                 childstack->r9 = usp;   /* function */
 264                 childstack->r10 = arg;
 265                 childregs->hae = alpha_mv.hae_cache,
 266                 childti->pcb.usp = 0;
 267                 return 0;
 268         }
 269         /* Note: if CLONE_SETTLS is not set, then we must inherit the
 270            value from the parent, which will have been set by the block
 271            copy in dup_task_struct.  This is non-intuitive, but is
 272            required for proper operation in the case of a threaded
 273            application calling fork.  */
 274         if (clone_flags & CLONE_SETTLS)
 275                 childti->pcb.unique = regs->r20;
 276         childti->pcb.usp = usp ?: rdusp();
 277         *childregs = *regs;
 278         childregs->r0 = 0;
 279         childregs->r19 = 0;
 280         childregs->r20 = 1;     /* OSF/1 has some strange fork() semantics.  */
 281         regs->r20 = 0;
 282         stack = ((struct switch_stack *) regs) - 1;
 283         *childstack = *stack;
 284         childstack->r26 = (unsigned long) ret_from_fork;
 285         return 0;
 286 }
 287
 288 /*
 289  * Fill in the user structure for a ELF core dump.
 290  */
 291 void
 292 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
 293 {
 294         /* switch stack follows right below pt_regs: */
 295         struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
 296
 297         dest[ 0] = pt->r0;
 298         dest[ 1] = pt->r1;
 299         dest[ 2] = pt->r2;
 300         dest[ 3] = pt->r3;
 301         dest[ 4] = pt->r4;
 302         dest[ 5] = pt->r5;
 303         dest[ 6] = pt->r6;
 304         dest[ 7] = pt->r7;
 305         dest[ 8] = pt->r8;
 306         dest[ 9] = sw->r9;
 307         dest[10] = sw->r10;
 308         dest[11] = sw->r11;
 309         dest[12] = sw->r12;
 310         dest[13] = sw->r13;
 311         dest[14] = sw->r14;
 312         dest[15] = sw->r15;
 313         dest[16] = pt->r16;
 314         dest[17] = pt->r17;
 315         dest[18] = pt->r18;
 316         dest[19] = pt->r19;
 317         dest[20] = pt->r20;
 318         dest[21] = pt->r21;
 319         dest[22] = pt->r22;
 320         dest[23] = pt->r23;
 321         dest[24] = pt->r24;
 322         dest[25] = pt->r25;
 323         dest[26] = pt->r26;
 324         dest[27] = pt->r27;
 325         dest[28] = pt->r28;
 326         dest[29] = pt->gp;
 327         dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
 328         dest[31] = pt->pc;
 329
 330         /* Once upon a time this was the PS value.  Which is stupid
 331            since that is always 8 for usermode.  Usurped for the more
 332            useful value of the thread's UNIQUE field.  */
 333         dest[32] = ti->pcb.unique;
 334 }
 335 EXPORT_SYMBOL(dump_elf_thread);
 336
 337 int
 338 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
 339 {
 340         dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
 341         return 1;
 342 }
 343 EXPORT_SYMBOL(dump_elf_task);
 344
 345 int
 346 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
 347 {
 348         struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
 349         memcpy(dest, sw->fp, 32 * 8);
 350         return 1;
 351 }
 352 EXPORT_SYMBOL(dump_elf_task_fp);
 353
 354 /*
 355  * Return saved PC of a blocked thread.  This assumes the frame
 356  * pointer is the 6th saved long on the kernel stack and that the
 357  * saved return address is the first long in the frame.  This all
 358  * holds provided the thread blocked through a call to schedule() ($15
 359  * is the frame pointer in schedule() and $15 is saved at offset 48 by
 360  * entry.S:do_switch_stack).
 361  *
 362  * Under heavy swap load I've seen this lose in an ugly way.  So do
 363  * some extra sanity checking on the ranges we expect these pointers
 364  * to be in so that we can fail gracefully.  This is just for ps after
 365  * all.  -- r~
 366  */
 367
 368 unsigned long
 369 thread_saved_pc(struct task_struct *t)
 370 {
 371         unsigned long base = (unsigned long)task_stack_page(t);
 372         unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
 373
 374         if (sp > base && sp+6*8 < base + 16*1024) {
 375                 fp = ((unsigned long*)sp)[6];
 376                 if (fp > sp && fp < base + 16*1024)
 377                         return *(unsigned long *)fp;
 378         }
 379
 380         return 0;
 381 }
 382
 383 unsigned long
 384 get_wchan(struct task_struct *p)
 385 {
 386         unsigned long schedule_frame;
 387         unsigned long pc;
 388         if (!p || p == current || p->state == TASK_RUNNING)
 389                 return 0;
 390         /*
 391          * This one depends on the frame size of schedule().  Do a
 392          * "disass schedule" in gdb to find the frame size.  Also, the
 393          * code assumes that sleep_on() follows immediately after
 394          * interruptible_sleep_on() and that add_timer() follows
 395          * immediately after interruptible_sleep().  Ugly, isn't it?
 396          * Maybe adding a wchan field to task_struct would be better,
 397          * after all...
 398          */
 399
 400         pc = thread_saved_pc(p);
 401         if (in_sched_functions(pc)) {
 402                 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
 403                 return ((unsigned long *)schedule_frame)[12];
 404         }
 405         return pc;
 406 }