2 * linux/arch/alpha/kernel/process.c
4 * Copyright (C) 1995 Linus Torvalds
8 * This file handles the architecture-dependent parts of process handling.
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/kernel.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>
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>
33 #include <asm/uaccess.h>
35 #include <asm/pgtable.h>
36 #include <asm/hwrpb.h>
43 * Power off function, if any
45 void (*pm_power_off)(void) = machine_power_off;
46 EXPORT_SYMBOL(pm_power_off);
51 set_thread_flag(TIF_POLLING_NRFLAG);
54 /* FIXME -- EV6 and LCA45 know how to power down
57 while (!need_resched())
70 common_shutdown_1(void *generic_ptr)
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();
77 /* No point in taking interrupts anymore. */
80 cpup = (struct percpu_struct *)
81 ((unsigned long)hwrpb + hwrpb->processor_offset
82 + hwrpb->processor_size * cpuid);
83 pflags = &cpup->flags;
86 /* Clear reason to "default"; clear "bootstrap in progress". */
87 flags &= ~0x00ff0001UL;
90 /* Secondaries halt here. */
91 if (cpuid != boot_cpuid) {
92 flags |= 0x00040000UL; /* "remain halted" */
94 set_cpu_present(cpuid, false);
95 set_cpu_possible(cpuid, false);
100 if (how->mode == LINUX_REBOOT_CMD_RESTART) {
101 if (!how->restart_cmd) {
102 flags |= 0x00020000UL; /* "cold bootstrap" */
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.
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" */
115 flags |= 0x00040000UL; /* "remain halted" */
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))
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. */
134 /* This has the effect of resetting the VGA video origin. */
135 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
137 pci_restore_srm_config();
141 if (alpha_mv.kill_arch)
142 alpha_mv.kill_arch(how->mode);
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. */
158 common_shutdown(int mode, char *restart_cmd)
160 struct halt_info args;
162 args.restart_cmd = restart_cmd;
163 on_each_cpu(common_shutdown_1, &args, 0);
167 machine_restart(char *restart_cmd)
169 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
176 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
181 machine_power_off(void)
183 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
187 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever
188 saved in the context it's used. */
191 show_regs(struct pt_regs *regs)
193 dik_show_regs(regs, NULL);
197 * Re-start a thread when doing execve()
200 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
206 EXPORT_SYMBOL(start_thread);
209 * Free current thread data structures etc..
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));
224 /* Clean slate for TLS. */
225 current_thread_info()->pcb.unique = 0;
229 release_thread(struct task_struct *dead_task)
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
239 * Notice that "fork()" is implemented in terms of clone,
240 * with parameters (SIGCHLD, 0).
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)
250 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid);
254 alpha_vfork(struct pt_regs *regs)
256 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
257 regs, 0, NULL, NULL);
261 * Copy an alpha thread..
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().
272 copy_thread(unsigned long clone_flags, unsigned long usp,
273 unsigned long unused,
274 struct task_struct * p, struct pt_regs * regs)
276 extern void ret_from_fork(void);
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;
283 stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
285 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
286 childregs = (struct pt_regs *)
287 (stack_offset + PAGE_SIZE + task_stack_page(p));
293 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
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 */
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;
319 * Fill in the user structure for a ELF core dump.
322 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
324 /* switch stack follows right below pt_regs: */
325 struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
357 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
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;
365 EXPORT_SYMBOL(dump_elf_thread);
368 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
370 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
373 EXPORT_SYMBOL(dump_elf_task);
376 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
378 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
379 memcpy(dest, sw->fp, 32 * 8);
382 EXPORT_SYMBOL(dump_elf_task_fp);
385 * sys_execve() executes a new program.
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)
395 filename = getname(ufilename);
396 error = PTR_ERR(filename);
397 if (IS_ERR(filename))
399 error = do_execve(filename, argv, envp, regs);
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).
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
420 thread_saved_pc(struct task_struct *t)
422 unsigned long base = (unsigned long)task_stack_page(t);
423 unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
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;
435 get_wchan(struct task_struct *p)
437 unsigned long schedule_frame;
439 if (!p || p == current || p->state == TASK_RUNNING)
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,
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];
459 int kernel_execve(const char *path, const char *const argv[], const char *const envp[])
461 /* Avoid the HAE being gratuitously wrong, which would cause us
462 to do the whole turn off interrupts thing and restore it. */
463 struct pt_regs regs = {.hae = alpha_mv.hae_cache};
464 int err = do_execve(path, argv, envp, ®s);
466 struct pt_regs *p = current_pt_regs();
467 /* copy regs to normal position and off to userland we go... */
469 __asm__ __volatile__ (
471 "br $31, ret_from_sys_call"
476 EXPORT_SYMBOL(kernel_execve);