arch/alpha/kernel/process.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/alpha/kernel/process.c
   4  *
   5  *  Copyright (C) 1995  Linus Torvalds
   6  */
   7
   8 /*
   9  * This file handles the architecture-dependent parts of process handling.
  10  */
  11
  12 #include <linux/errno.h>
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/sched/debug.h>
  16 #include <linux/sched/task.h>
  17 #include <linux/sched/task_stack.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mm.h>
  20 #include <linux/smp.h>
  21 #include <linux/stddef.h>
  22 #include <linux/unistd.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/user.h>
  25 #include <linux/time.h>
  26 #include <linux/major.h>
  27 #include <linux/stat.h>
  28 #include <linux/vt.h>
  29 #include <linux/mman.h>
  30 #include <linux/elfcore.h>
  31 #include <linux/reboot.h>
  32 #include <linux/tty.h>
  33 #include <linux/console.h>
  34 #include <linux/slab.h>
  35 #include <linux/rcupdate.h>
  36
  37 #include <asm/reg.h>
  38 #include <linux/uaccess.h>
  39 #include <asm/io.h>
  40 #include <asm/hwrpb.h>
  41 #include <asm/fpu.h>
  42
  43 #include "proto.h"
  44 #include "pci_impl.h"
  45
  46 /*
  47  * Power off function, if any
  48  */
  49 void (*pm_power_off)(void) = machine_power_off;
  50 EXPORT_SYMBOL(pm_power_off);
  51
  52 #ifdef CONFIG_ALPHA_WTINT
  53 /*
  54  * Sleep the CPU.
  55  * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts.
  56  */
  57 void arch_cpu_idle(void)
  58 {
  59         wtint(0);
  60         raw_local_irq_enable();
  61 }
  62
  63 void arch_cpu_idle_dead(void)
  64 {
  65         wtint(INT_MAX);
  66 }
  67 #endif /* ALPHA_WTINT */
  68
  69 struct halt_info {
  70         int mode;
  71         char *restart_cmd;
  72 };
  73
  74 static void
  75 common_shutdown_1(void *generic_ptr)
  76 {
  77         struct halt_info *how = (struct halt_info *)generic_ptr;
  78         struct percpu_struct *cpup;
  79         unsigned long *pflags, flags;
  80         int cpuid = smp_processor_id();
  81
  82         /* No point in taking interrupts anymore. */
  83         local_irq_disable();
  84
  85         cpup = (struct percpu_struct *)
  86                         ((unsigned long)hwrpb + hwrpb->processor_offset
  87                          + hwrpb->processor_size * cpuid);
  88         pflags = &cpup->flags;
  89         flags = *pflags;
  90
  91         /* Clear reason to "default"; clear "bootstrap in progress". */
  92         flags &= ~0x00ff0001UL;
  93
  94 #ifdef CONFIG_SMP
  95         /* Secondaries halt here. */
  96         if (cpuid != boot_cpuid) {
  97                 flags |= 0x00040000UL; /* "remain halted" */
  98                 *pflags = flags;
  99                 set_cpu_present(cpuid, false);
 100                 set_cpu_possible(cpuid, false);
 101                 halt();
 102         }
 103 #endif
 104
 105         if (how->mode == LINUX_REBOOT_CMD_RESTART) {
 106                 if (!how->restart_cmd) {
 107                         flags |= 0x00020000UL; /* "cold bootstrap" */
 108                 } else {
 109                         /* For SRM, we could probably set environment
 110                            variables to get this to work.  We'd have to
 111                            delay this until after srm_paging_stop unless
 112                            we ever got srm_fixup working.
 113
 114                            At the moment, SRM will use the last boot device,
 115                            but the file and flags will be the defaults, when
 116                            doing a "warm" bootstrap.  */
 117                         flags |= 0x00030000UL; /* "warm bootstrap" */
 118                 }
 119         } else {
 120                 flags |= 0x00040000UL; /* "remain halted" */
 121         }
 122         *pflags = flags;
 123
 124 #ifdef CONFIG_SMP
 125         /* Wait for the secondaries to halt. */
 126         set_cpu_present(boot_cpuid, false);
 127         set_cpu_possible(boot_cpuid, false);
 128         while (cpumask_weight(cpu_present_mask))
 129                 barrier();
 130 #endif
 131
 132         /* If booted from SRM, reset some of the original environment. */
 133         if (alpha_using_srm) {
 134 #ifdef CONFIG_DUMMY_CONSOLE
 135                 /* If we've gotten here after SysRq-b, leave interrupt
 136                    context before taking over the console. */
 137                 if (in_irq())
 138                         irq_exit();
 139                 /* This has the effect of resetting the VGA video origin.  */
 140                 console_lock();
 141                 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
 142                 console_unlock();
 143 #endif
 144                 pci_restore_srm_config();
 145                 set_hae(srm_hae);
 146         }
 147
 148         if (alpha_mv.kill_arch)
 149                 alpha_mv.kill_arch(how->mode);
 150
 151         if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
 152                 /* Unfortunately, since MILO doesn't currently understand
 153                    the hwrpb bits above, we can't reliably halt the
 154                    processor and keep it halted.  So just loop.  */
 155                 return;
 156         }
 157
 158         if (alpha_using_srm)
 159                 srm_paging_stop();
 160
 161         halt();
 162 }
 163
 164 static void
 165 common_shutdown(int mode, char *restart_cmd)
 166 {
 167         struct halt_info args;
 168         args.mode = mode;
 169         args.restart_cmd = restart_cmd;
 170         on_each_cpu(common_shutdown_1, &args, 0);
 171 }
 172
 173 void
 174 machine_restart(char *restart_cmd)
 175 {
 176         common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
 177 }
 178
 179
 180 void
 181 machine_halt(void)
 182 {
 183         common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
 184 }
 185
 186
 187 void
 188 machine_power_off(void)
 189 {
 190         common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
 191 }
 192
 193
 194 /* Used by sysrq-p, among others.  I don't believe r9-r15 are ever
 195    saved in the context it's used.  */
 196
 197 void
 198 show_regs(struct pt_regs *regs)
 199 {
 200         show_regs_print_info(KERN_DEFAULT);
 201         dik_show_regs(regs, NULL);
 202 }
 203
 204 /*
 205  * Re-start a thread when doing execve()
 206  */
 207 void
 208 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 209 {
 210         regs->pc = pc;
 211         regs->ps = 8;
 212         wrusp(sp);
 213 }
 214 EXPORT_SYMBOL(start_thread);
 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  * Copy architecture-specific thread state
 235  */
 236 int copy_thread(unsigned long clone_flags, unsigned long usp,
 237                 unsigned long kthread_arg, struct task_struct *p,
 238                 unsigned long tls)
 239 {
 240         extern void ret_from_fork(void);
 241         extern void ret_from_kernel_thread(void);
 242
 243         struct thread_info *childti = task_thread_info(p);
 244         struct pt_regs *childregs = task_pt_regs(p);
 245         struct pt_regs *regs = current_pt_regs();
 246         struct switch_stack *childstack, *stack;
 247
 248         childstack = ((struct switch_stack *) childregs) - 1;
 249         childti->pcb.ksp = (unsigned long) childstack;
 250         childti->pcb.flags = 1; /* set FEN, clear everything else */
 251
 252         if (unlikely(p->flags & PF_KTHREAD)) {
 253                 /* kernel thread */
 254                 memset(childstack, 0,
 255                         sizeof(struct switch_stack) + sizeof(struct pt_regs));
 256                 childstack->r26 = (unsigned long) ret_from_kernel_thread;
 257                 childstack->r9 = usp;   /* function */
 258                 childstack->r10 = kthread_arg;
 259                 childregs->hae = alpha_mv.hae_cache,
 260                 childti->pcb.usp = 0;
 261                 return 0;
 262         }
 263         /* Note: if CLONE_SETTLS is not set, then we must inherit the
 264            value from the parent, which will have been set by the block
 265            copy in dup_task_struct.  This is non-intuitive, but is
 266            required for proper operation in the case of a threaded
 267            application calling fork.  */
 268         if (clone_flags & CLONE_SETTLS)
 269                 childti->pcb.unique = tls;
 270         else
 271                 regs->r20 = 0;  /* OSF/1 has some strange fork() semantics.  */
 272         childti->pcb.usp = usp ?: rdusp();
 273         *childregs = *regs;
 274         childregs->r0 = 0;
 275         childregs->r19 = 0;
 276         childregs->r20 = 1;     /* OSF/1 has some strange fork() semantics.  */
 277         stack = ((struct switch_stack *) regs) - 1;
 278         *childstack = *stack;
 279         childstack->r26 = (unsigned long) ret_from_fork;
 280         return 0;
 281 }
 282
 283 /*
 284  * Fill in the user structure for a ELF core dump.
 285  */
 286 void
 287 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
 288 {
 289         /* switch stack follows right below pt_regs: */
 290         struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
 291
 292         dest[ 0] = pt->r0;
 293         dest[ 1] = pt->r1;
 294         dest[ 2] = pt->r2;
 295         dest[ 3] = pt->r3;
 296         dest[ 4] = pt->r4;
 297         dest[ 5] = pt->r5;
 298         dest[ 6] = pt->r6;
 299         dest[ 7] = pt->r7;
 300         dest[ 8] = pt->r8;
 301         dest[ 9] = sw->r9;
 302         dest[10] = sw->r10;
 303         dest[11] = sw->r11;
 304         dest[12] = sw->r12;
 305         dest[13] = sw->r13;
 306         dest[14] = sw->r14;
 307         dest[15] = sw->r15;
 308         dest[16] = pt->r16;
 309         dest[17] = pt->r17;
 310         dest[18] = pt->r18;
 311         dest[19] = pt->r19;
 312         dest[20] = pt->r20;
 313         dest[21] = pt->r21;
 314         dest[22] = pt->r22;
 315         dest[23] = pt->r23;
 316         dest[24] = pt->r24;
 317         dest[25] = pt->r25;
 318         dest[26] = pt->r26;
 319         dest[27] = pt->r27;
 320         dest[28] = pt->r28;
 321         dest[29] = pt->gp;
 322         dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
 323         dest[31] = pt->pc;
 324
 325         /* Once upon a time this was the PS value.  Which is stupid
 326            since that is always 8 for usermode.  Usurped for the more
 327            useful value of the thread's UNIQUE field.  */
 328         dest[32] = ti->pcb.unique;
 329 }
 330 EXPORT_SYMBOL(dump_elf_thread);
 331
 332 int
 333 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
 334 {
 335         dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
 336         return 1;
 337 }
 338 EXPORT_SYMBOL(dump_elf_task);
 339
 340 int
 341 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
 342 {
 343         struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
 344         memcpy(dest, sw->fp, 32 * 8);
 345         return 1;
 346 }
 347 EXPORT_SYMBOL(dump_elf_task_fp);
 348
 349 /*
 350  * Return saved PC of a blocked thread.  This assumes the frame
 351  * pointer is the 6th saved long on the kernel stack and that the
 352  * saved return address is the first long in the frame.  This all
 353  * holds provided the thread blocked through a call to schedule() ($15
 354  * is the frame pointer in schedule() and $15 is saved at offset 48 by
 355  * entry.S:do_switch_stack).
 356  *
 357  * Under heavy swap load I've seen this lose in an ugly way.  So do
 358  * some extra sanity checking on the ranges we expect these pointers
 359  * to be in so that we can fail gracefully.  This is just for ps after
 360  * all.  -- r~
 361  */
 362
 363 static unsigned long
 364 thread_saved_pc(struct task_struct *t)
 365 {
 366         unsigned long base = (unsigned long)task_stack_page(t);
 367         unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
 368
 369         if (sp > base && sp+6*8 < base + 16*1024) {
 370                 fp = ((unsigned long*)sp)[6];
 371                 if (fp > sp && fp < base + 16*1024)
 372                         return *(unsigned long *)fp;
 373         }
 374
 375         return 0;
 376 }
 377
 378 unsigned long
 379 get_wchan(struct task_struct *p)
 380 {
 381         unsigned long schedule_frame;
 382         unsigned long pc;
 383         if (!p || p == current || p->state == TASK_RUNNING)
 384                 return 0;
 385         /*
 386          * This one depends on the frame size of schedule().  Do a
 387          * "disass schedule" in gdb to find the frame size.  Also, the
 388          * code assumes that sleep_on() follows immediately after
 389          * interruptible_sleep_on() and that add_timer() follows
 390          * immediately after interruptible_sleep().  Ugly, isn't it?
 391          * Maybe adding a wchan field to task_struct would be better,
 392          * after all...
 393          */
 394
 395         pc = thread_saved_pc(p);
 396         if (in_sched_functions(pc)) {
 397                 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
 398                 return ((unsigned long *)schedule_frame)[12];
 399         }
 400         return pc;
 401 }