/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/config.h>
 12#include <linux/errno.h>
 13#include <linux/module.h>
 14#include <linux/sched.h>
 15#include <linux/kernel.h>
 16#include <linux/mm.h>
 17#include <linux/smp.h>
 18#include <linux/smp_lock.h>
 19#include <linux/stddef.h>
 20#include <linux/unistd.h>
 21#include <linux/ptrace.h>
 22#include <linux/slab.h>
 23#include <linux/user.h>
 24#include <linux/a.out.h>
 25#include <linux/utsname.h>
 26#include <linux/time.h>
 27#include <linux/major.h>
 28#include <linux/stat.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
 35#include <asm/reg.h>
 36#include <asm/uaccess.h>
 37#include <asm/system.h>
 38#include <asm/io.h>
 39#include <asm/pgtable.h>
 40#include <asm/hwrpb.h>
 41#include <asm/fpu.h>
 42
 43#include "proto.h"
 44#include "pci_impl.h"
 45
 46void default_idle(void)
 47{
 48	barrier();
 49}
 50
 51void
 52cpu_idle(void)
 53{
 54	while (1) {
 55		void (*idle)(void) = default_idle;
 56		/* FIXME -- EV6 and LCA45 know how to power down
 57		   the CPU.  */
 58
 59		while (!need_resched())
 60			idle();
 61		schedule();
 62	}
 63}
 64
 65
 66struct halt_info {
 67	int mode;
 68	char *restart_cmd;
 69};
 70
 71static void
 72common_shutdown_1(void *generic_ptr)
 73{
 74	struct halt_info *how = (struct halt_info *)generic_ptr;
 75	struct percpu_struct *cpup;
 76	unsigned long *pflags, flags;
 77	int cpuid = smp_processor_id();
 78
 79	/* No point in taking interrupts anymore. */
 80	local_irq_disable();
 81
 82	cpup = (struct percpu_struct *)
 83			((unsigned long)hwrpb + hwrpb->processor_offset
 84			 + hwrpb->processor_size * cpuid);
 85	pflags = &cpup->flags;
 86	flags = *pflags;
 87
 88	/* Clear reason to "default"; clear "bootstrap in progress". */
 89	flags &= ~0x00ff0001UL;
 90
 91#ifdef CONFIG_SMP
 92	/* Secondaries halt here. */
 93	if (cpuid != boot_cpuid) {
 94		flags |= 0x00040000UL; /* "remain halted" */
 95		*pflags = flags;
 96		clear_bit(cpuid, &cpu_present_mask);
 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	cpu_clear(boot_cpuid, cpu_possible_map);
123	while (cpus_weight(cpu_possible_map))
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		/* This has the effect of resetting the VGA video origin.  */
131		take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
132#endif
133		pci_restore_srm_config();
134		set_hae(srm_hae);
135	}
136
137	if (alpha_mv.kill_arch)
138		alpha_mv.kill_arch(how->mode);
139
140	if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
141		/* Unfortunately, since MILO doesn't currently understand
142		   the hwrpb bits above, we can't reliably halt the 
143		   processor and keep it halted.  So just loop.  */
144		return;
145	}
146
147	if (alpha_using_srm)
148		srm_paging_stop();
149
150	halt();
151}
152
153static void
154common_shutdown(int mode, char *restart_cmd)
155{
156	struct halt_info args;
157	args.mode = mode;
158	args.restart_cmd = restart_cmd;
159	on_each_cpu(common_shutdown_1, &args, 1, 0);
160}
161
162void
163machine_restart(char *restart_cmd)
164{
165	common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
166}
167
168EXPORT_SYMBOL(machine_restart);
169
170void
171machine_halt(void)
172{
173	common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
174}
175
176EXPORT_SYMBOL(machine_halt);
177
178void
179machine_power_off(void)
180{
181	common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
182}
183
184EXPORT_SYMBOL(machine_power_off);
185
186/* Used by sysrq-p, among others.  I don't believe r9-r15 are ever
187   saved in the context it's used.  */
188
189void
190show_regs(struct pt_regs *regs)
191{
192	dik_show_regs(regs, NULL);
193}
194
195/*
196 * Re-start a thread when doing execve()
197 */
198void
199start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
200{
201	set_fs(USER_DS);
202	regs->pc = pc;
203	regs->ps = 8;
204	wrusp(sp);
205}
206
207/*
208 * Free current thread data structures etc..
209 */
210void
211exit_thread(void)
212{
213}
214
215void
216flush_thread(void)
217{
218	/* Arrange for each exec'ed process to start off with a clean slate
219	   with respect to the FPU.  This is all exceptions disabled.  */
220	current_thread_info()->ieee_state = 0;
221	wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
222
223	/* Clean slate for TLS.  */
224	current_thread_info()->pcb.unique = 0;
225}
226
227void
228release_thread(struct task_struct *dead_task)
229{
230}
231
232/*
233 * "alpha_clone()".. By the time we get here, the
234 * non-volatile registers have also been saved on the
235 * stack. We do some ugly pointer stuff here.. (see
236 * also copy_thread)
237 *
238 * Notice that "fork()" is implemented in terms of clone,
239 * with parameters (SIGCHLD, 0).
240 */
241int
242alpha_clone(unsigned long clone_flags, unsigned long usp,
243	    int __user *parent_tid, int __user *child_tid,
244	    unsigned long tls_value, struct pt_regs *regs)
245{
246	if (!usp)
247		usp = rdusp();
248
249	return do_fork(clone_flags, usp, regs, 0, parent_tid, child_tid);
250}
251
252int
253alpha_vfork(struct pt_regs *regs)
254{
255	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
256		       regs, 0, NULL, NULL);
257}
258
259/*
260 * Copy an alpha thread..
261 *
262 * Note the "stack_offset" stuff: when returning to kernel mode, we need
263 * to have some extra stack-space for the kernel stack that still exists
264 * after the "ret_from_fork".  When returning to user mode, we only want
265 * the space needed by the syscall stack frame (ie "struct pt_regs").
266 * Use the passed "regs" pointer to determine how much space we need
267 * for a kernel fork().
268 */
269
270int
271copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
272	    unsigned long unused,
273	    struct task_struct * p, struct pt_regs * regs)
274{
275	extern void ret_from_fork(void);
276
277	struct thread_info *childti = p->thread_info;
278	struct pt_regs * childregs;
279	struct switch_stack * childstack, *stack;
280	unsigned long stack_offset, settls;
281
282	stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
283	if (!(regs->ps & 8))
284		stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
285	childregs = (struct pt_regs *)
286	  (stack_offset + PAGE_SIZE + (long) childti);
287		
288	*childregs = *regs;
289	settls = regs->r20;
290	childregs->r0 = 0;
291	childregs->r19 = 0;
292	childregs->r20 = 1;	/* OSF/1 has some strange fork() semantics.  */
293	regs->r20 = 0;
294	stack = ((struct switch_stack *) regs) - 1;
295	childstack = ((struct switch_stack *) childregs) - 1;
296	*childstack = *stack;
297	childstack->r26 = (unsigned long) ret_from_fork;
298	childti->pcb.usp = usp;
299	childti->pcb.ksp = (unsigned long) childstack;
300	childti->pcb.flags = 1;	/* set FEN, clear everything else */
301
302	/* Set a new TLS for the child thread?  Peek back into the
303	   syscall arguments that we saved on syscall entry.  Oops,
304	   except we'd have clobbered it with the parent/child set
305	   of r20.  Read the saved copy.  */
306	/* Note: if CLONE_SETTLS is not set, then we must inherit the
307	   value from the parent, which will have been set by the block
308	   copy in dup_task_struct.  This is non-intuitive, but is
309	   required for proper operation in the case of a threaded
310	   application calling fork.  */
311	if (clone_flags & CLONE_SETTLS)
312		childti->pcb.unique = settls;
313
314	return 0;
315}
316
317/*
318 * Fill in the user structure for an ECOFF core dump.
319 */
320void
321dump_thread(struct pt_regs * pt, struct user * dump)
322{
323	/* switch stack follows right below pt_regs: */
324	struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
325
326	dump->magic = CMAGIC;
327	dump->start_code  = current->mm->start_code;
328	dump->start_data  = current->mm->start_data;
329	dump->start_stack = rdusp() & ~(PAGE_SIZE - 1);
330	dump->u_tsize = ((current->mm->end_code - dump->start_code)
331			 >> PAGE_SHIFT);
332	dump->u_dsize = ((current->mm->brk + PAGE_SIZE-1 - dump->start_data)
333			 >> PAGE_SHIFT);
334	dump->u_ssize = (current->mm->start_stack - dump->start_stack
335			 + PAGE_SIZE-1) >> PAGE_SHIFT;
336
337	/*
338	 * We store the registers in an order/format that is
339	 * compatible with DEC Unix/OSF/1 as this makes life easier
340	 * for gdb.
341	 */
342	dump->regs[EF_V0]  = pt->r0;
343	dump->regs[EF_T0]  = pt->r1;
344	dump->regs[EF_T1]  = pt->r2;
345	dump->regs[EF_T2]  = pt->r3;
346	dump->regs[EF_T3]  = pt->r4;
347	dump->regs[EF_T4]  = pt->r5;
348	dump->regs[EF_T5]  = pt->r6;
349	dump->regs[EF_T6]  = pt->r7;
350	dump->regs[EF_T7]  = pt->r8;
351	dump->regs[EF_S0]  = sw->r9;
352	dump->regs[EF_S1]  = sw->r10;
353	dump->regs[EF_S2]  = sw->r11;
354	dump->regs[EF_S3]  = sw->r12;
355	dump->regs[EF_S4]  = sw->r13;
356	dump->regs[EF_S5]  = sw->r14;
357	dump->regs[EF_S6]  = sw->r15;
358	dump->regs[EF_A3]  = pt->r19;
359	dump->regs[EF_A4]  = pt->r20;
360	dump->regs[EF_A5]  = pt->r21;
361	dump->regs[EF_T8]  = pt->r22;
362	dump->regs[EF_T9]  = pt->r23;
363	dump->regs[EF_T10] = pt->r24;
364	dump->regs[EF_T11] = pt->r25;
365	dump->regs[EF_RA]  = pt->r26;
366	dump->regs[EF_T12] = pt->r27;
367	dump->regs[EF_AT]  = pt->r28;
368	dump->regs[EF_SP]  = rdusp();
369	dump->regs[EF_PS]  = pt->ps;
370	dump->regs[EF_PC]  = pt->pc;
371	dump->regs[EF_GP]  = pt->gp;
372	dump->regs[EF_A0]  = pt->r16;
373	dump->regs[EF_A1]  = pt->r17;
374	dump->regs[EF_A2]  = pt->r18;
375	memcpy((char *)dump->regs + EF_SIZE, sw->fp, 32 * 8);
376}
377
378/*
379 * Fill in the user structure for a ELF core dump.
380 */
381void
382dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
383{
384	/* switch stack follows right below pt_regs: */
385	struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
386
387	dest[ 0] = pt->r0;
388	dest[ 1] = pt->r1;
389	dest[ 2] = pt->r2;
390	dest[ 3] = pt->r3;
391	dest[ 4] = pt->r4;
392	dest[ 5] = pt->r5;
393	dest[ 6] = pt->r6;
394	dest[ 7] = pt->r7;
395	dest[ 8] = pt->r8;
396	dest[ 9] = sw->r9;
397	dest[10] = sw->r10;
398	dest[11] = sw->r11;
399	dest[12] = sw->r12;
400	dest[13] = sw->r13;
401	dest[14] = sw->r14;
402	dest[15] = sw->r15;
403	dest[16] = pt->r16;
404	dest[17] = pt->r17;
405	dest[18] = pt->r18;
406	dest[19] = pt->r19;
407	dest[20] = pt->r20;
408	dest[21] = pt->r21;
409	dest[22] = pt->r22;
410	dest[23] = pt->r23;
411	dest[24] = pt->r24;
412	dest[25] = pt->r25;
413	dest[26] = pt->r26;
414	dest[27] = pt->r27;
415	dest[28] = pt->r28;
416	dest[29] = pt->gp;
417	dest[30] = rdusp();
418	dest[31] = pt->pc;
419
420	/* Once upon a time this was the PS value.  Which is stupid
421	   since that is always 8 for usermode.  Usurped for the more
422	   useful value of the thread's UNIQUE field.  */
423	dest[32] = ti->pcb.unique;
424}
425
426int
427dump_elf_task(elf_greg_t *dest, struct task_struct *task)
428{
429	struct thread_info *ti;
430	struct pt_regs *pt;
431
432	ti = task->thread_info;
433	pt = (struct pt_regs *)((unsigned long)ti + 2*PAGE_SIZE) - 1;
434
435	dump_elf_thread(dest, pt, ti);
436
437	return 1;
438}
439
440int
441dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
442{
443	struct thread_info *ti;
444	struct pt_regs *pt;
445	struct switch_stack *sw;
446
447	ti = task->thread_info;
448	pt = (struct pt_regs *)((unsigned long)ti + 2*PAGE_SIZE) - 1;
449	sw = (struct switch_stack *)pt - 1;
450
451	memcpy(dest, sw->fp, 32 * 8);
452
453	return 1;
454}
455
456/*
457 * sys_execve() executes a new program.
458 */
459asmlinkage int
460do_sys_execve(char __user *ufilename, char __user * __user *argv,
461	      char __user * __user *envp, struct pt_regs *regs)
462{
463	int error;
464	char *filename;
465
466	filename = getname(ufilename);
467	error = PTR_ERR(filename);
468	if (IS_ERR(filename))
469		goto out;
470	error = do_execve(filename, argv, envp, regs);
471	putname(filename);
472out:
473	return error;
474}
475
476/*
477 * Return saved PC of a blocked thread.  This assumes the frame
478 * pointer is the 6th saved long on the kernel stack and that the
479 * saved return address is the first long in the frame.  This all
480 * holds provided the thread blocked through a call to schedule() ($15
481 * is the frame pointer in schedule() and $15 is saved at offset 48 by
482 * entry.S:do_switch_stack).
483 *
484 * Under heavy swap load I've seen this lose in an ugly way.  So do
485 * some extra sanity checking on the ranges we expect these pointers
486 * to be in so that we can fail gracefully.  This is just for ps after
487 * all.  -- r~
488 */
489
490unsigned long
491thread_saved_pc(task_t *t)
492{
493	unsigned long base = (unsigned long)t->thread_info;
494	unsigned long fp, sp = t->thread_info->pcb.ksp;
495
496	if (sp > base && sp+6*8 < base + 16*1024) {
497		fp = ((unsigned long*)sp)[6];
498		if (fp > sp && fp < base + 16*1024)
499			return *(unsigned long *)fp;
500	}
501
502	return 0;
503}
504
505unsigned long
506get_wchan(struct task_struct *p)
507{
508	unsigned long schedule_frame;
509	unsigned long pc;
510	if (!p || p == current || p->state == TASK_RUNNING)
511		return 0;
512	/*
513	 * This one depends on the frame size of schedule().  Do a
514	 * "disass schedule" in gdb to find the frame size.  Also, the
515	 * code assumes that sleep_on() follows immediately after
516	 * interruptible_sleep_on() and that add_timer() follows
517	 * immediately after interruptible_sleep().  Ugly, isn't it?
518	 * Maybe adding a wchan field to task_struct would be better,
519	 * after all...
520	 */
521
522	pc = thread_saved_pc(p);
523	if (in_sched_functions(pc)) {
524		schedule_frame = ((unsigned long *)p->thread_info->pcb.ksp)[6];
525		return ((unsigned long *)schedule_frame)[12];
526	}
527	return pc;
528}