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                 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 }