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>
31 #include <linux/rcupdate.h>
34 #include <asm/uaccess.h>
36 #include <asm/pgtable.h>
37 #include <asm/hwrpb.h>
44 * Power off function, if any
46 void (*pm_power_off)(void) = machine_power_off;
47 EXPORT_SYMBOL(pm_power_off);
52 set_thread_flag(TIF_POLLING_NRFLAG);
55 /* FIXME -- EV6 and LCA45 know how to power down
59 while (!need_resched())
63 schedule_preempt_disabled();
74 common_shutdown_1(void *generic_ptr)
76 struct halt_info *how = (struct halt_info *)generic_ptr;
77 struct percpu_struct *cpup;
78 unsigned long *pflags, flags;
79 int cpuid = smp_processor_id();
81 /* No point in taking interrupts anymore. */
84 cpup = (struct percpu_struct *)
85 ((unsigned long)hwrpb + hwrpb->processor_offset
86 + hwrpb->processor_size * cpuid);
87 pflags = &cpup->flags;
90 /* Clear reason to "default"; clear "bootstrap in progress". */
91 flags &= ~0x00ff0001UL;
94 /* Secondaries halt here. */
95 if (cpuid != boot_cpuid) {
96 flags |= 0x00040000UL; /* "remain halted" */
98 set_cpu_present(cpuid, false);
99 set_cpu_possible(cpuid, false);
104 if (how->mode == LINUX_REBOOT_CMD_RESTART) {
105 if (!how->restart_cmd) {
106 flags |= 0x00020000UL; /* "cold bootstrap" */
108 /* For SRM, we could probably set environment
109 variables to get this to work. We'd have to
110 delay this until after srm_paging_stop unless
111 we ever got srm_fixup working.
113 At the moment, SRM will use the last boot device,
114 but the file and flags will be the defaults, when
115 doing a "warm" bootstrap. */
116 flags |= 0x00030000UL; /* "warm bootstrap" */
119 flags |= 0x00040000UL; /* "remain halted" */
124 /* Wait for the secondaries to halt. */
125 set_cpu_present(boot_cpuid, false);
126 set_cpu_possible(boot_cpuid, false);
127 while (cpumask_weight(cpu_present_mask))
131 /* If booted from SRM, reset some of the original environment. */
132 if (alpha_using_srm) {
133 #ifdef CONFIG_DUMMY_CONSOLE
134 /* If we've gotten here after SysRq-b, leave interrupt
135 context before taking over the console. */
138 /* This has the effect of resetting the VGA video origin. */
139 take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
141 pci_restore_srm_config();
145 if (alpha_mv.kill_arch)
146 alpha_mv.kill_arch(how->mode);
148 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
149 /* Unfortunately, since MILO doesn't currently understand
150 the hwrpb bits above, we can't reliably halt the
151 processor and keep it halted. So just loop. */
162 common_shutdown(int mode, char *restart_cmd)
164 struct halt_info args;
166 args.restart_cmd = restart_cmd;
167 on_each_cpu(common_shutdown_1, &args, 0);
171 machine_restart(char *restart_cmd)
173 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
180 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
185 machine_power_off(void)
187 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
191 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever
192 saved in the context it's used. */
195 show_regs(struct pt_regs *regs)
197 dik_show_regs(regs, NULL);
201 * Re-start a thread when doing execve()
204 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
210 EXPORT_SYMBOL(start_thread);
213 * Free current thread data structures etc..
223 /* Arrange for each exec'ed process to start off with a clean slate
224 with respect to the FPU. This is all exceptions disabled. */
225 current_thread_info()->ieee_state = 0;
226 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
228 /* Clean slate for TLS. */
229 current_thread_info()->pcb.unique = 0;
233 release_thread(struct task_struct *dead_task)
238 * "alpha_clone()".. By the time we get here, the
239 * non-volatile registers have also been saved on the
240 * stack. We do some ugly pointer stuff here.. (see
243 * Notice that "fork()" is implemented in terms of clone,
244 * with parameters (SIGCHLD, 0).
247 alpha_clone(unsigned long clone_flags, unsigned long usp,
248 int __user *parent_tid, int __user *child_tid,
249 unsigned long tls_value, struct pt_regs *regs)
254 return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid);
258 alpha_vfork(struct pt_regs *regs)
260 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
261 regs, 0, NULL, NULL);
265 * Copy an alpha thread..
267 * Note the "stack_offset" stuff: when returning to kernel mode, we need
268 * to have some extra stack-space for the kernel stack that still exists
269 * after the "ret_from_fork". When returning to user mode, we only want
270 * the space needed by the syscall stack frame (ie "struct pt_regs").
271 * Use the passed "regs" pointer to determine how much space we need
272 * for a kernel fork().
276 copy_thread(unsigned long clone_flags, unsigned long usp,
277 unsigned long unused,
278 struct task_struct * p, struct pt_regs * regs)
280 extern void ret_from_fork(void);
282 struct thread_info *childti = task_thread_info(p);
283 struct pt_regs * childregs;
284 struct switch_stack * childstack, *stack;
285 unsigned long stack_offset, settls;
287 stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
289 stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
290 childregs = (struct pt_regs *)
291 (stack_offset + PAGE_SIZE + task_stack_page(p));
297 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
299 stack = ((struct switch_stack *) regs) - 1;
300 childstack = ((struct switch_stack *) childregs) - 1;
301 *childstack = *stack;
302 childstack->r26 = (unsigned long) ret_from_fork;
303 childti->pcb.usp = usp;
304 childti->pcb.ksp = (unsigned long) childstack;
305 childti->pcb.flags = 1; /* set FEN, clear everything else */
307 /* Set a new TLS for the child thread? Peek back into the
308 syscall arguments that we saved on syscall entry. Oops,
309 except we'd have clobbered it with the parent/child set
310 of r20. Read the saved copy. */
311 /* Note: if CLONE_SETTLS is not set, then we must inherit the
312 value from the parent, which will have been set by the block
313 copy in dup_task_struct. This is non-intuitive, but is
314 required for proper operation in the case of a threaded
315 application calling fork. */
316 if (clone_flags & CLONE_SETTLS)
317 childti->pcb.unique = settls;
323 * Fill in the user structure for a ELF core dump.
326 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
328 /* switch stack follows right below pt_regs: */
329 struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
361 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
364 /* Once upon a time this was the PS value. Which is stupid
365 since that is always 8 for usermode. Usurped for the more
366 useful value of the thread's UNIQUE field. */
367 dest[32] = ti->pcb.unique;
369 EXPORT_SYMBOL(dump_elf_thread);
372 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
374 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
377 EXPORT_SYMBOL(dump_elf_task);
380 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
382 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
383 memcpy(dest, sw->fp, 32 * 8);
386 EXPORT_SYMBOL(dump_elf_task_fp);
389 * sys_execve() executes a new program.
392 do_sys_execve(const char __user *ufilename,
393 const char __user *const __user *argv,
394 const char __user *const __user *envp, struct pt_regs *regs)
399 filename = getname(ufilename);
400 error = PTR_ERR(filename);
401 if (IS_ERR(filename))
403 error = do_execve(filename, argv, envp, regs);
410 * Return saved PC of a blocked thread. This assumes the frame
411 * pointer is the 6th saved long on the kernel stack and that the
412 * saved return address is the first long in the frame. This all
413 * holds provided the thread blocked through a call to schedule() ($15
414 * is the frame pointer in schedule() and $15 is saved at offset 48 by
415 * entry.S:do_switch_stack).
417 * Under heavy swap load I've seen this lose in an ugly way. So do
418 * some extra sanity checking on the ranges we expect these pointers
419 * to be in so that we can fail gracefully. This is just for ps after
424 thread_saved_pc(struct task_struct *t)
426 unsigned long base = (unsigned long)task_stack_page(t);
427 unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
429 if (sp > base && sp+6*8 < base + 16*1024) {
430 fp = ((unsigned long*)sp)[6];
431 if (fp > sp && fp < base + 16*1024)
432 return *(unsigned long *)fp;
439 get_wchan(struct task_struct *p)
441 unsigned long schedule_frame;
443 if (!p || p == current || p->state == TASK_RUNNING)
446 * This one depends on the frame size of schedule(). Do a
447 * "disass schedule" in gdb to find the frame size. Also, the
448 * code assumes that sleep_on() follows immediately after
449 * interruptible_sleep_on() and that add_timer() follows
450 * immediately after interruptible_sleep(). Ugly, isn't it?
451 * Maybe adding a wchan field to task_struct would be better,
455 pc = thread_saved_pc(p);
456 if (in_sched_functions(pc)) {
457 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
458 return ((unsigned long *)schedule_frame)[12];
463 int kernel_execve(const char *path, const char *const argv[], const char *const envp[])
465 /* Avoid the HAE being gratuitously wrong, which would cause us
466 to do the whole turn off interrupts thing and restore it. */
467 struct pt_regs regs = {.hae = alpha_mv.hae_cache};
468 int err = do_execve(path, argv, envp, ®s);
470 struct pt_regs *p = current_pt_regs();
471 /* copy regs to normal position and off to userland we go... */
473 __asm__ __volatile__ (
475 "br $31, ret_from_sys_call"
480 EXPORT_SYMBOL(kernel_execve);