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/io.h>
  35 #include <asm/pgtable.h>
  36 #include <asm/hwrpb.h>
  37 #include <asm/fpu.h>
  38
  39 #include "proto.h"
  40 #include "pci_impl.h"
  41
  42 /*
  43  * Power off function, if any
  44  */
  45 void (*pm_power_off)(void) = machine_power_off;
  46 EXPORT_SYMBOL(pm_power_off);
  47
  48 void
  49 cpu_idle(void)
  50 {
  51         set_thread_flag(TIF_POLLING_NRFLAG);
  52
  53         while (1) {
  54                 /* FIXME -- EV6 and LCA45 know how to power down
  55                    the CPU.  */
  56
  57                 while (!need_resched())
  58                         cpu_relax();
  59                 schedule();
  60         }
  61 }
  62
  63
  64 struct halt_info {
  65         int mode;
  66         char *restart_cmd;
  67 };
  68
  69 static void
  70 common_shutdown_1(void *generic_ptr)
  71 {
  72         struct halt_info *how = (struct halt_info *)generic_ptr;
  73         struct percpu_struct *cpup;
  74         unsigned long *pflags, flags;
  75         int cpuid = smp_processor_id();
  76
  77         /* No point in taking interrupts anymore. */
  78         local_irq_disable();
  79
  80         cpup = (struct percpu_struct *)
  81                         ((unsigned long)hwrpb + hwrpb->processor_offset
  82                          + hwrpb->processor_size * cpuid);
  83         pflags = &cpup->flags;
  84         flags = *pflags;
  85
  86         /* Clear reason to "default"; clear "bootstrap in progress". */
  87         flags &= ~0x00ff0001UL;
  88
  89 #ifdef CONFIG_SMP
  90         /* Secondaries halt here. */
  91         if (cpuid != boot_cpuid) {
  92                 flags |= 0x00040000UL; /* "remain halted" */
  93                 *pflags = flags;
  94                 set_cpu_present(cpuid, false);
  95                 set_cpu_possible(cpuid, false);
  96                 halt();
  97         }
  98 #endif
  99
 100         if (how->mode == LINUX_REBOOT_CMD_RESTART) {
 101                 if (!how->restart_cmd) {
 102                         flags |= 0x00020000UL; /* "cold bootstrap" */
 103                 } else {
 104                         /* For SRM, we could probably set environment
 105                            variables to get this to work.  We'd have to
 106                            delay this until after srm_paging_stop unless
 107                            we ever got srm_fixup working.
 108
 109                            At the moment, SRM will use the last boot device,
 110                            but the file and flags will be the defaults, when
 111                            doing a "warm" bootstrap.  */
 112                         flags |= 0x00030000UL; /* "warm bootstrap" */
 113                 }
 114         } else {
 115                 flags |= 0x00040000UL; /* "remain halted" */
 116         }
 117         *pflags = flags;
 118
 119 #ifdef CONFIG_SMP
 120         /* Wait for the secondaries to halt. */
 121         set_cpu_present(boot_cpuid, false);
 122         set_cpu_possible(boot_cpuid, false);
 123         while (cpumask_weight(cpu_present_mask))
 124                 barrier();
 125 #endif
 126
 127         /* If booted from SRM, reset some of the original environment. */
 128         if (alpha_using_srm) {
 129 #ifdef CONFIG_DUMMY_CONSOLE
 130                 /* If we've gotten here after SysRq-b, leave interrupt
 131                    context before taking over the console. */
 132                 if (in_interrupt())
 133                         irq_exit();
 134                 /* This has the effect of resetting the VGA video origin.  */
 135                 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
 136 #endif
 137                 pci_restore_srm_config();
 138                 set_hae(srm_hae);
 139         }
 140
 141         if (alpha_mv.kill_arch)
 142                 alpha_mv.kill_arch(how->mode);
 143
 144         if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
 145                 /* Unfortunately, since MILO doesn't currently understand
 146                    the hwrpb bits above, we can't reliably halt the
 147                    processor and keep it halted.  So just loop.  */
 148                 return;
 149         }
 150
 151         if (alpha_using_srm)
 152                 srm_paging_stop();
 153
 154         halt();
 155 }
 156
 157 static void
 158 common_shutdown(int mode, char *restart_cmd)
 159 {
 160         struct halt_info args;
 161         args.mode = mode;
 162         args.restart_cmd = restart_cmd;
 163         on_each_cpu(common_shutdown_1, &args, 0);
 164 }
 165
 166 void
 167 machine_restart(char *restart_cmd)
 168 {
 169         common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
 170 }
 171
 172
 173 void
 174 machine_halt(void)
 175 {
 176         common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
 177 }
 178
 179
 180 void
 181 machine_power_off(void)
 182 {
 183         common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
 184 }
 185
 186
 187 /* Used by sysrq-p, among others.  I don't believe r9-r15 are ever
 188    saved in the context it's used.  */
 189
 190 void
 191 show_regs(struct pt_regs *regs)
 192 {
 193         dik_show_regs(regs, NULL);
 194 }
 195
 196 /*
 197  * Re-start a thread when doing execve()
 198  */
 199 void
 200 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 201 {
 202         regs->pc = pc;
 203         regs->ps = 8;
 204         wrusp(sp);
 205 }
 206 EXPORT_SYMBOL(start_thread);
 207
 208 /*
 209  * Free current thread data structures etc..
 210  */
 211 void
 212 exit_thread(void)
 213 {
 214 }
 215
 216 void
 217 flush_thread(void)
 218 {
 219         /* Arrange for each exec'ed process to start off with a clean slate
 220            with respect to the FPU.  This is all exceptions disabled.  */
 221         current_thread_info()->ieee_state = 0;
 222         wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
 223
 224         /* Clean slate for TLS.  */
 225         current_thread_info()->pcb.unique = 0;
 226 }
 227
 228 void
 229 release_thread(struct task_struct *dead_task)
 230 {
 231 }
 232
 233 /*
 234  * "alpha_clone()".. By the time we get here, the
 235  * non-volatile registers have also been saved on the
 236  * stack. We do some ugly pointer stuff here.. (see
 237  * also copy_thread)
 238  *
 239  * Notice that "fork()" is implemented in terms of clone,
 240  * with parameters (SIGCHLD, 0).
 241  */
 242 int
 243 alpha_clone(unsigned long clone_flags, unsigned long usp,
 244             int __user *parent_tid, int __user *child_tid,
 245             unsigned long tls_value, struct pt_regs *regs)
 246 {
 247         if (!usp)
 248                 usp = rdusp();
 249
 250         return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid);
 251 }
 252
 253 int
 254 alpha_vfork(struct pt_regs *regs)
 255 {
 256         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
 257                        regs, 0, NULL, NULL);
 258 }
 259
 260 /*
 261  * Copy an alpha thread..
 262  *
 263  * Note the "stack_offset" stuff: when returning to kernel mode, we need
 264  * to have some extra stack-space for the kernel stack that still exists
 265  * after the "ret_from_fork".  When returning to user mode, we only want
 266  * the space needed by the syscall stack frame (ie "struct pt_regs").
 267  * Use the passed "regs" pointer to determine how much space we need
 268  * for a kernel fork().
 269  */
 270
 271 int
 272 copy_thread(unsigned long clone_flags, unsigned long usp,
 273             unsigned long unused,
 274             struct task_struct * p, struct pt_regs * regs)
 275 {
 276         extern void ret_from_fork(void);
 277
 278         struct thread_info *childti = task_thread_info(p);
 279         struct pt_regs * childregs;
 280         struct switch_stack * childstack, *stack;
 281         unsigned long stack_offset, settls;
 282
 283         stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
 284         if (!(regs->ps & 8))
 285                 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
 286         childregs = (struct pt_regs *)
 287           (stack_offset + PAGE_SIZE + task_stack_page(p));
 288
 289         *childregs = *regs;
 290         settls = regs->r20;
 291         childregs->r0 = 0;
 292         childregs->r19 = 0;
 293         childregs->r20 = 1;     /* OSF/1 has some strange fork() semantics.  */
 294         regs->r20 = 0;
 295         stack = ((struct switch_stack *) regs) - 1;
 296         childstack = ((struct switch_stack *) childregs) - 1;
 297         *childstack = *stack;
 298         childstack->r26 = (unsigned long) ret_from_fork;
 299         childti->pcb.usp = usp;
 300         childti->pcb.ksp = (unsigned long) childstack;
 301         childti->pcb.flags = 1; /* set FEN, clear everything else */
 302
 303         /* Set a new TLS for the child thread?  Peek back into the
 304            syscall arguments that we saved on syscall entry.  Oops,
 305            except we'd have clobbered it with the parent/child set
 306            of r20.  Read the saved copy.  */
 307         /* Note: if CLONE_SETTLS is not set, then we must inherit the
 308            value from the parent, which will have been set by the block
 309            copy in dup_task_struct.  This is non-intuitive, but is
 310            required for proper operation in the case of a threaded
 311            application calling fork.  */
 312         if (clone_flags & CLONE_SETTLS)
 313                 childti->pcb.unique = settls;
 314
 315         return 0;
 316 }
 317
 318 /*
 319  * Fill in the user structure for a ELF core dump.
 320  */
 321 void
 322 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
 323 {
 324         /* switch stack follows right below pt_regs: */
 325         struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
 326
 327         dest[ 0] = pt->r0;
 328         dest[ 1] = pt->r1;
 329         dest[ 2] = pt->r2;
 330         dest[ 3] = pt->r3;
 331         dest[ 4] = pt->r4;
 332         dest[ 5] = pt->r5;
 333         dest[ 6] = pt->r6;
 334         dest[ 7] = pt->r7;
 335         dest[ 8] = pt->r8;
 336         dest[ 9] = sw->r9;
 337         dest[10] = sw->r10;
 338         dest[11] = sw->r11;
 339         dest[12] = sw->r12;
 340         dest[13] = sw->r13;
 341         dest[14] = sw->r14;
 342         dest[15] = sw->r15;
 343         dest[16] = pt->r16;
 344         dest[17] = pt->r17;
 345         dest[18] = pt->r18;
 346         dest[19] = pt->r19;
 347         dest[20] = pt->r20;
 348         dest[21] = pt->r21;
 349         dest[22] = pt->r22;
 350         dest[23] = pt->r23;
 351         dest[24] = pt->r24;
 352         dest[25] = pt->r25;
 353         dest[26] = pt->r26;
 354         dest[27] = pt->r27;
 355         dest[28] = pt->r28;
 356         dest[29] = pt->gp;
 357         dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
 358         dest[31] = pt->pc;
 359
 360         /* Once upon a time this was the PS value.  Which is stupid
 361            since that is always 8 for usermode.  Usurped for the more
 362            useful value of the thread's UNIQUE field.  */
 363         dest[32] = ti->pcb.unique;
 364 }
 365 EXPORT_SYMBOL(dump_elf_thread);
 366
 367 int
 368 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
 369 {
 370         dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
 371         return 1;
 372 }
 373 EXPORT_SYMBOL(dump_elf_task);
 374
 375 int
 376 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
 377 {
 378         struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
 379         memcpy(dest, sw->fp, 32 * 8);
 380         return 1;
 381 }
 382 EXPORT_SYMBOL(dump_elf_task_fp);
 383
 384 /*
 385  * sys_execve() executes a new program.
 386  */
 387 asmlinkage int
 388 do_sys_execve(const char __user *ufilename,
 389               const char __user *const __user *argv,
 390               const char __user *const __user *envp, struct pt_regs *regs)
 391 {
 392         int error;
 393         char *filename;
 394
 395         filename = getname(ufilename);
 396         error = PTR_ERR(filename);
 397         if (IS_ERR(filename))
 398                 goto out;
 399         error = do_execve(filename, argv, envp, regs);
 400         putname(filename);
 401 out:
 402         return error;
 403 }
 404
 405 /*
 406  * Return saved PC of a blocked thread.  This assumes the frame
 407  * pointer is the 6th saved long on the kernel stack and that the
 408  * saved return address is the first long in the frame.  This all
 409  * holds provided the thread blocked through a call to schedule() ($15
 410  * is the frame pointer in schedule() and $15 is saved at offset 48 by
 411  * entry.S:do_switch_stack).
 412  *
 413  * Under heavy swap load I've seen this lose in an ugly way.  So do
 414  * some extra sanity checking on the ranges we expect these pointers
 415  * to be in so that we can fail gracefully.  This is just for ps after
 416  * all.  -- r~
 417  */
 418
 419 unsigned long
 420 thread_saved_pc(struct task_struct *t)
 421 {
 422         unsigned long base = (unsigned long)task_stack_page(t);
 423         unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
 424
 425         if (sp > base && sp+6*8 < base + 16*1024) {
 426                 fp = ((unsigned long*)sp)[6];
 427                 if (fp > sp && fp < base + 16*1024)
 428                         return *(unsigned long *)fp;
 429         }
 430
 431         return 0;
 432 }
 433
 434 unsigned long
 435 get_wchan(struct task_struct *p)
 436 {
 437         unsigned long schedule_frame;
 438         unsigned long pc;
 439         if (!p || p == current || p->state == TASK_RUNNING)
 440                 return 0;
 441         /*
 442          * This one depends on the frame size of schedule().  Do a
 443          * "disass schedule" in gdb to find the frame size.  Also, the
 444          * code assumes that sleep_on() follows immediately after
 445          * interruptible_sleep_on() and that add_timer() follows
 446          * immediately after interruptible_sleep().  Ugly, isn't it?
 447          * Maybe adding a wchan field to task_struct would be better,
 448          * after all...
 449          */
 450
 451         pc = thread_saved_pc(p);
 452         if (in_sched_functions(pc)) {
 453                 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
 454                 return ((unsigned long *)schedule_frame)[12];
 455         }
 456         return pc;
 457 }