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
  32 #include <asm/reg.h>
  33 #include <asm/uaccess.h>
  34 #include <asm/system.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         set_thread_flag(TIF_POLLING_NRFLAG);
  53
  54         while (1) {
  55                 /* FIXME -- EV6 and LCA45 know how to power down
  56                    the CPU.  */
  57
  58                 while (!need_resched())
  59                         cpu_relax();
  60                 schedule();
  61         }
  62 }
  63
  64
  65 struct halt_info {
  66         int mode;
  67         char *restart_cmd;
  68 };
  69
  70 static void
  71 common_shutdown_1(void *generic_ptr)
  72 {
  73         struct halt_info *how = (struct halt_info *)generic_ptr;
  74         struct percpu_struct *cpup;
  75         unsigned long *pflags, flags;
  76         int cpuid = smp_processor_id();
  77
  78         /* No point in taking interrupts anymore. */
  79         local_irq_disable();
  80
  81         cpup = (struct percpu_struct *)
  82                         ((unsigned long)hwrpb + hwrpb->processor_offset
  83                          + hwrpb->processor_size * cpuid);
  84         pflags = &cpup->flags;
  85         flags = *pflags;
  86
  87         /* Clear reason to "default"; clear "bootstrap in progress". */
  88         flags &= ~0x00ff0001UL;
  89
  90 #ifdef CONFIG_SMP
  91         /* Secondaries halt here. */
  92         if (cpuid != boot_cpuid) {
  93                 flags |= 0x00040000UL; /* "remain halted" */
  94                 *pflags = flags;
  95                 set_cpu_present(cpuid, false);
  96                 set_cpu_possible(cpuid, false);
  97                 halt();
  98         }
  99 #endif
 100
 101         if (how->mode == LINUX_REBOOT_CMD_RESTART) {
 102                 if (!how->restart_cmd) {
 103                         flags |= 0x00020000UL; /* "cold bootstrap" */
 104                 } else {
 105                         /* For SRM, we could probably set environment
 106                            variables to get this to work.  We'd have to
 107                            delay this until after srm_paging_stop unless
 108                            we ever got srm_fixup working.
 109
 110                            At the moment, SRM will use the last boot device,
 111                            but the file and flags will be the defaults, when
 112                            doing a "warm" bootstrap.  */
 113                         flags |= 0x00030000UL; /* "warm bootstrap" */
 114                 }
 115         } else {
 116                 flags |= 0x00040000UL; /* "remain halted" */
 117         }
 118         *pflags = flags;
 119
 120 #ifdef CONFIG_SMP
 121         /* Wait for the secondaries to halt. */
 122         set_cpu_present(boot_cpuid, false);
 123         set_cpu_possible(boot_cpuid, false);
 124         while (cpus_weight(cpu_present_map))
 125                 barrier();
 126 #endif
 127
 128         /* If booted from SRM, reset some of the original environment. */
 129         if (alpha_using_srm) {
 130 #ifdef CONFIG_DUMMY_CONSOLE
 131                 /* If we've gotten here after SysRq-b, leave interrupt
 132                    context before taking over the console. */
 133                 if (in_interrupt())
 134                         irq_exit();
 135                 /* This has the effect of resetting the VGA video origin.  */
 136                 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
 137 #endif
 138                 pci_restore_srm_config();
 139                 set_hae(srm_hae);
 140         }
 141
 142         if (alpha_mv.kill_arch)
 143                 alpha_mv.kill_arch(how->mode);
 144
 145         if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
 146                 /* Unfortunately, since MILO doesn't currently understand
 147                    the hwrpb bits above, we can't reliably halt the
 148                    processor and keep it halted.  So just loop.  */
 149                 return;
 150         }
 151
 152         if (alpha_using_srm)
 153                 srm_paging_stop();
 154
 155         halt();
 156 }
 157
 158 static void
 159 common_shutdown(int mode, char *restart_cmd)
 160 {
 161         struct halt_info args;
 162         args.mode = mode;
 163         args.restart_cmd = restart_cmd;
 164         on_each_cpu(common_shutdown_1, &args, 0);
 165 }
 166
 167 void
 168 machine_restart(char *restart_cmd)
 169 {
 170         common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
 171 }
 172
 173
 174 void
 175 machine_halt(void)
 176 {
 177         common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
 178 }
 179
 180
 181 void
 182 machine_power_off(void)
 183 {
 184         common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
 185 }
 186
 187
 188 /* Used by sysrq-p, among others.  I don't believe r9-r15 are ever
 189    saved in the context it's used.  */
 190
 191 void
 192 show_regs(struct pt_regs *regs)
 193 {
 194         dik_show_regs(regs, NULL);
 195 }
 196
 197 /*
 198  * Re-start a thread when doing execve()
 199  */
 200 void
 201 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 202 {
 203         set_fs(USER_DS);
 204         regs->pc = pc;
 205         regs->ps = 8;
 206         wrusp(sp);
 207 }
 208 EXPORT_SYMBOL(start_thread);
 209
 210 /*
 211  * Free current thread data structures etc..
 212  */
 213 void
 214 exit_thread(void)
 215 {
 216 }
 217
 218 void
 219 flush_thread(void)
 220 {
 221         /* Arrange for each exec'ed process to start off with a clean slate
 222            with respect to the FPU.  This is all exceptions disabled.  */
 223         current_thread_info()->ieee_state = 0;
 224         wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
 225
 226         /* Clean slate for TLS.  */
 227         current_thread_info()->pcb.unique = 0;
 228 }
 229
 230 void
 231 release_thread(struct task_struct *dead_task)
 232 {
 233 }
 234
 235 /*
 236  * "alpha_clone()".. By the time we get here, the
 237  * non-volatile registers have also been saved on the
 238  * stack. We do some ugly pointer stuff here.. (see
 239  * also copy_thread)
 240  *
 241  * Notice that "fork()" is implemented in terms of clone,
 242  * with parameters (SIGCHLD, 0).
 243  */
 244 int
 245 alpha_clone(unsigned long clone_flags, unsigned long usp,
 246             int __user *parent_tid, int __user *child_tid,
 247             unsigned long tls_value, struct pt_regs *regs)
 248 {
 249         if (!usp)
 250                 usp = rdusp();
 251
 252         return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid);
 253 }
 254
 255 int
 256 alpha_vfork(struct pt_regs *regs)
 257 {
 258         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
 259                        regs, 0, NULL, NULL);
 260 }
 261
 262 /*
 263  * Copy an alpha thread..
 264  *
 265  * Note the "stack_offset" stuff: when returning to kernel mode, we need
 266  * to have some extra stack-space for the kernel stack that still exists
 267  * after the "ret_from_fork".  When returning to user mode, we only want
 268  * the space needed by the syscall stack frame (ie "struct pt_regs").
 269  * Use the passed "regs" pointer to determine how much space we need
 270  * for a kernel fork().
 271  */
 272
 273 int
 274 copy_thread(unsigned long clone_flags, unsigned long usp,
 275             unsigned long unused,
 276             struct task_struct * p, struct pt_regs * regs)
 277 {
 278         extern void ret_from_fork(void);
 279
 280         struct thread_info *childti = task_thread_info(p);
 281         struct pt_regs * childregs;
 282         struct switch_stack * childstack, *stack;
 283         unsigned long stack_offset, settls;
 284
 285         stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
 286         if (!(regs->ps & 8))
 287                 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
 288         childregs = (struct pt_regs *)
 289           (stack_offset + PAGE_SIZE + task_stack_page(p));
 290
 291         *childregs = *regs;
 292         settls = regs->r20;
 293         childregs->r0 = 0;
 294         childregs->r19 = 0;
 295         childregs->r20 = 1;     /* OSF/1 has some strange fork() semantics.  */
 296         regs->r20 = 0;
 297         stack = ((struct switch_stack *) regs) - 1;
 298         childstack = ((struct switch_stack *) childregs) - 1;
 299         *childstack = *stack;
 300         childstack->r26 = (unsigned long) ret_from_fork;
 301         childti->pcb.usp = usp;
 302         childti->pcb.ksp = (unsigned long) childstack;
 303         childti->pcb.flags = 1; /* set FEN, clear everything else */
 304
 305         /* Set a new TLS for the child thread?  Peek back into the
 306            syscall arguments that we saved on syscall entry.  Oops,
 307            except we'd have clobbered it with the parent/child set
 308            of r20.  Read the saved copy.  */
 309         /* Note: if CLONE_SETTLS is not set, then we must inherit the
 310            value from the parent, which will have been set by the block
 311            copy in dup_task_struct.  This is non-intuitive, but is
 312            required for proper operation in the case of a threaded
 313            application calling fork.  */
 314         if (clone_flags & CLONE_SETTLS)
 315                 childti->pcb.unique = settls;
 316
 317         return 0;
 318 }
 319
 320 /*
 321  * Fill in the user structure for a ELF core dump.
 322  */
 323 void
 324 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
 325 {
 326         /* switch stack follows right below pt_regs: */
 327         struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
 328
 329         dest[ 0] = pt->r0;
 330         dest[ 1] = pt->r1;
 331         dest[ 2] = pt->r2;
 332         dest[ 3] = pt->r3;
 333         dest[ 4] = pt->r4;
 334         dest[ 5] = pt->r5;
 335         dest[ 6] = pt->r6;
 336         dest[ 7] = pt->r7;
 337         dest[ 8] = pt->r8;
 338         dest[ 9] = sw->r9;
 339         dest[10] = sw->r10;
 340         dest[11] = sw->r11;
 341         dest[12] = sw->r12;
 342         dest[13] = sw->r13;
 343         dest[14] = sw->r14;
 344         dest[15] = sw->r15;
 345         dest[16] = pt->r16;
 346         dest[17] = pt->r17;
 347         dest[18] = pt->r18;
 348         dest[19] = pt->r19;
 349         dest[20] = pt->r20;
 350         dest[21] = pt->r21;
 351         dest[22] = pt->r22;
 352         dest[23] = pt->r23;
 353         dest[24] = pt->r24;
 354         dest[25] = pt->r25;
 355         dest[26] = pt->r26;
 356         dest[27] = pt->r27;
 357         dest[28] = pt->r28;
 358         dest[29] = pt->gp;
 359         dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
 360         dest[31] = pt->pc;
 361
 362         /* Once upon a time this was the PS value.  Which is stupid
 363            since that is always 8 for usermode.  Usurped for the more
 364            useful value of the thread's UNIQUE field.  */
 365         dest[32] = ti->pcb.unique;
 366 }
 367 EXPORT_SYMBOL(dump_elf_thread);
 368
 369 int
 370 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
 371 {
 372         dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
 373         return 1;
 374 }
 375 EXPORT_SYMBOL(dump_elf_task);
 376
 377 int
 378 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
 379 {
 380         struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
 381         memcpy(dest, sw->fp, 32 * 8);
 382         return 1;
 383 }
 384 EXPORT_SYMBOL(dump_elf_task_fp);
 385
 386 /*
 387  * sys_execve() executes a new program.
 388  */
 389 asmlinkage int
 390 do_sys_execve(const char __user *ufilename,
 391               const char __user *const __user *argv,
 392               const char __user *const __user *envp, struct pt_regs *regs)
 393 {
 394         int error;
 395         char *filename;
 396
 397         filename = getname(ufilename);
 398         error = PTR_ERR(filename);
 399         if (IS_ERR(filename))
 400                 goto out;
 401         error = do_execve(filename, argv, envp, regs);
 402         putname(filename);
 403 out:
 404         return error;
 405 }
 406
 407 /*
 408  * Return saved PC of a blocked thread.  This assumes the frame
 409  * pointer is the 6th saved long on the kernel stack and that the
 410  * saved return address is the first long in the frame.  This all
 411  * holds provided the thread blocked through a call to schedule() ($15
 412  * is the frame pointer in schedule() and $15 is saved at offset 48 by
 413  * entry.S:do_switch_stack).
 414  *
 415  * Under heavy swap load I've seen this lose in an ugly way.  So do
 416  * some extra sanity checking on the ranges we expect these pointers
 417  * to be in so that we can fail gracefully.  This is just for ps after
 418  * all.  -- r~
 419  */
 420
 421 unsigned long
 422 thread_saved_pc(struct task_struct *t)
 423 {
 424         unsigned long base = (unsigned long)task_stack_page(t);
 425         unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
 426
 427         if (sp > base && sp+6*8 < base + 16*1024) {
 428                 fp = ((unsigned long*)sp)[6];
 429                 if (fp > sp && fp < base + 16*1024)
 430                         return *(unsigned long *)fp;
 431         }
 432
 433         return 0;
 434 }
 435
 436 unsigned long
 437 get_wchan(struct task_struct *p)
 438 {
 439         unsigned long schedule_frame;
 440         unsigned long pc;
 441         if (!p || p == current || p->state == TASK_RUNNING)
 442                 return 0;
 443         /*
 444          * This one depends on the frame size of schedule().  Do a
 445          * "disass schedule" in gdb to find the frame size.  Also, the
 446          * code assumes that sleep_on() follows immediately after
 447          * interruptible_sleep_on() and that add_timer() follows
 448          * immediately after interruptible_sleep().  Ugly, isn't it?
 449          * Maybe adding a wchan field to task_struct would be better,
 450          * after all...
 451          */
 452
 453         pc = thread_saved_pc(p);
 454         if (in_sched_functions(pc)) {
 455                 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
 456                 return ((unsigned long *)schedule_frame)[12];
 457         }
 458         return pc;
 459 }