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