1/*
 
 
  2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  3 * Copyright 2003 PathScale, Inc.
  4 * Licensed under the GPL
  5 */
  6
  7#include <linux/stddef.h>
  8#include <linux/err.h>
  9#include <linux/hardirq.h>
 10#include <linux/mm.h>
 11#include <linux/module.h>
 12#include <linux/personality.h>
 13#include <linux/proc_fs.h>
 14#include <linux/ptrace.h>
 15#include <linux/random.h>
 16#include <linux/slab.h>
 17#include <linux/sched.h>
 
 
 
 18#include <linux/seq_file.h>
 19#include <linux/tick.h>
 20#include <linux/threads.h>
 21#include <linux/tracehook.h>
 22#include <asm/current.h>
 23#include <asm/pgtable.h>
 24#include <asm/mmu_context.h>
 25#include <asm/uaccess.h>
 26#include "as-layout.h"
 27#include "kern_util.h"
 28#include "os.h"
 29#include "skas.h"
 
 30
 31/*
 32 * This is a per-cpu array.  A processor only modifies its entry and it only
 33 * cares about its entry, so it's OK if another processor is modifying its
 34 * entry.
 35 */
 36struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
 37
 38static inline int external_pid(void)
 39{
 40	/* FIXME: Need to look up userspace_pid by cpu */
 41	return userspace_pid[0];
 42}
 43
 44int pid_to_processor_id(int pid)
 45{
 46	int i;
 47
 48	for (i = 0; i < ncpus; i++) {
 49		if (cpu_tasks[i].pid == pid)
 50			return i;
 51	}
 52	return -1;
 53}
 54
 55void free_stack(unsigned long stack, int order)
 56{
 57	free_pages(stack, order);
 58}
 59
 60unsigned long alloc_stack(int order, int atomic)
 61{
 62	unsigned long page;
 63	gfp_t flags = GFP_KERNEL;
 64
 65	if (atomic)
 66		flags = GFP_ATOMIC;
 67	page = __get_free_pages(flags, order);
 68
 69	return page;
 70}
 71
 72int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 73{
 74	int pid;
 75
 76	current->thread.request.u.thread.proc = fn;
 77	current->thread.request.u.thread.arg = arg;
 78	pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
 79		      &current->thread.regs, 0, NULL, NULL);
 80	return pid;
 81}
 82EXPORT_SYMBOL(kernel_thread);
 83
 84static inline void set_current(struct task_struct *task)
 85{
 86	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
 87		{ external_pid(), task });
 88}
 89
 90extern void arch_switch_to(struct task_struct *to);
 91
 92void *__switch_to(struct task_struct *from, struct task_struct *to)
 93{
 94	to->thread.prev_sched = from;
 95	set_current(to);
 96
 97	do {
 98		current->thread.saved_task = NULL;
 99
100		switch_threads(&from->thread.switch_buf,
101			       &to->thread.switch_buf);
102
103		arch_switch_to(current);
104
105		if (current->thread.saved_task)
106			show_regs(&(current->thread.regs));
107		to = current->thread.saved_task;
108		from = current;
109	} while (current->thread.saved_task);
110
111	return current->thread.prev_sched;
112}
113
114void interrupt_end(void)
115{
 
 
116	if (need_resched())
117		schedule();
118	if (test_thread_flag(TIF_SIGPENDING))
119		do_signal();
120	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
121		tracehook_notify_resume(&current->thread.regs);
122}
123
124void exit_thread(void)
125{
126}
127
128int get_current_pid(void)
129{
130	return task_pid_nr(current);
131}
132
133/*
134 * This is called magically, by its address being stuffed in a jmp_buf
135 * and being longjmp-d to.
136 */
137void new_thread_handler(void)
138{
139	int (*fn)(void *), n;
140	void *arg;
141
142	if (current->thread.prev_sched != NULL)
143		schedule_tail(current->thread.prev_sched);
144	current->thread.prev_sched = NULL;
145
146	fn = current->thread.request.u.thread.proc;
147	arg = current->thread.request.u.thread.arg;
148
149	/*
150	 * The return value is 1 if the kernel thread execs a process,
151	 * 0 if it just exits
152	 */
153	n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
154	if (n == 1) {
155		/* Handle any immediate reschedules or signals */
156		interrupt_end();
157		userspace(&current->thread.regs.regs);
158	}
159	else do_exit(0);
160}
161
162/* Called magically, see new_thread_handler above */
163void fork_handler(void)
164{
165	force_flush_all();
166
167	schedule_tail(current->thread.prev_sched);
168
169	/*
170	 * XXX: if interrupt_end() calls schedule, this call to
171	 * arch_switch_to isn't needed. We could want to apply this to
172	 * improve performance. -bb
173	 */
174	arch_switch_to(current);
175
176	current->thread.prev_sched = NULL;
177
178	/* Handle any immediate reschedules or signals */
179	interrupt_end();
180
181	userspace(&current->thread.regs.regs);
182}
183
184int copy_thread(unsigned long clone_flags, unsigned long sp,
185		unsigned long stack_top, struct task_struct * p,
186		struct pt_regs *regs)
187{
188	void (*handler)(void);
 
189	int ret = 0;
190
191	p->thread = (struct thread_struct) INIT_THREAD;
192
193	if (current->thread.forking) {
194	  	memcpy(&p->thread.regs.regs, &regs->regs,
195		       sizeof(p->thread.regs.regs));
196		UPT_SET_SYSCALL_RETURN(&p->thread.regs.regs, 0);
197		if (sp != 0)
198			REGS_SP(p->thread.regs.regs.gp) = sp;
199
200		handler = fork_handler;
201
202		arch_copy_thread(&current->thread.arch, &p->thread.arch);
203	}
204	else {
205		get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
206		p->thread.request.u.thread = current->thread.request.u.thread;
 
207		handler = new_thread_handler;
208	}
209
210	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
211
212	if (current->thread.forking) {
213		clear_flushed_tls(p);
214
215		/*
216		 * Set a new TLS for the child thread?
217		 */
218		if (clone_flags & CLONE_SETTLS)
219			ret = arch_copy_tls(p);
220	}
221
222	return ret;
223}
224
225void initial_thread_cb(void (*proc)(void *), void *arg)
226{
227	int save_kmalloc_ok = kmalloc_ok;
228
229	kmalloc_ok = 0;
230	initial_thread_cb_skas(proc, arg);
231	kmalloc_ok = save_kmalloc_ok;
232}
233
234void default_idle(void)
235{
236	unsigned long long nsecs;
237
238	while (1) {
239		/* endless idle loop with no priority at all */
240
241		/*
242		 * although we are an idle CPU, we do not want to
243		 * get into the scheduler unnecessarily.
244		 */
245		if (need_resched())
246			schedule();
247
248		tick_nohz_idle_enter();
249		rcu_idle_enter();
250		nsecs = disable_timer();
251		idle_sleep(nsecs);
252		rcu_idle_exit();
253		tick_nohz_idle_exit();
254	}
255}
256
257void cpu_idle(void)
258{
259	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
260	default_idle();
 
261}
262
263int __cant_sleep(void) {
264	return in_atomic() || irqs_disabled() || in_interrupt();
265	/* Is in_interrupt() really needed? */
266}
267
268int user_context(unsigned long sp)
269{
270	unsigned long stack;
271
272	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
273	return stack != (unsigned long) current_thread_info();
274}
275
276extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
277
278void do_uml_exitcalls(void)
279{
280	exitcall_t *call;
281
282	call = &__uml_exitcall_end;
283	while (--call >= &__uml_exitcall_begin)
284		(*call)();
285}
286
287char *uml_strdup(const char *string)
288{
289	return kstrdup(string, GFP_KERNEL);
290}
291EXPORT_SYMBOL(uml_strdup);
292
293int copy_to_user_proc(void __user *to, void *from, int size)
294{
295	return copy_to_user(to, from, size);
296}
297
298int copy_from_user_proc(void *to, void __user *from, int size)
299{
300	return copy_from_user(to, from, size);
301}
302
303int clear_user_proc(void __user *buf, int size)
304{
305	return clear_user(buf, size);
306}
307
308int strlen_user_proc(char __user *str)
309{
310	return strlen_user(str);
311}
312
313int smp_sigio_handler(void)
314{
315#ifdef CONFIG_SMP
316	int cpu = current_thread_info()->cpu;
317	IPI_handler(cpu);
318	if (cpu != 0)
319		return 1;
320#endif
321	return 0;
322}
323
324int cpu(void)
325{
326	return current_thread_info()->cpu;
327}
328
329static atomic_t using_sysemu = ATOMIC_INIT(0);
330int sysemu_supported;
331
332void set_using_sysemu(int value)
333{
334	if (value > sysemu_supported)
335		return;
336	atomic_set(&using_sysemu, value);
337}
338
339int get_using_sysemu(void)
340{
341	return atomic_read(&using_sysemu);
342}
343
344static int sysemu_proc_show(struct seq_file *m, void *v)
345{
346	seq_printf(m, "%d\n", get_using_sysemu());
347	return 0;
348}
349
350static int sysemu_proc_open(struct inode *inode, struct file *file)
351{
352	return single_open(file, sysemu_proc_show, NULL);
353}
354
355static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
356				 size_t count, loff_t *pos)
357{
358	char tmp[2];
359
360	if (copy_from_user(tmp, buf, 1))
361		return -EFAULT;
362
363	if (tmp[0] >= '0' && tmp[0] <= '2')
364		set_using_sysemu(tmp[0] - '0');
365	/* We use the first char, but pretend to write everything */
366	return count;
367}
368
369static const struct file_operations sysemu_proc_fops = {
370	.owner		= THIS_MODULE,
371	.open		= sysemu_proc_open,
372	.read		= seq_read,
373	.llseek		= seq_lseek,
374	.release	= single_release,
375	.write		= sysemu_proc_write,
376};
377
378int __init make_proc_sysemu(void)
379{
380	struct proc_dir_entry *ent;
381	if (!sysemu_supported)
382		return 0;
383
384	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
385
386	if (ent == NULL)
387	{
388		printk(KERN_WARNING "Failed to register /proc/sysemu\n");
389		return 0;
390	}
391
392	return 0;
393}
394
395late_initcall(make_proc_sysemu);
396
397int singlestepping(void * t)
398{
399	struct task_struct *task = t ? t : current;
400
401	if (!(task->ptrace & PT_DTRACE))
402		return 0;
403
404	if (task->thread.singlestep_syscall)
405		return 1;
406
407	return 2;
408}
409
410/*
411 * Only x86 and x86_64 have an arch_align_stack().
412 * All other arches have "#define arch_align_stack(x) (x)"
413 * in their asm/system.h
414 * As this is included in UML from asm-um/system-generic.h,
415 * we can use it to behave as the subarch does.
416 */
417#ifndef arch_align_stack
418unsigned long arch_align_stack(unsigned long sp)
419{
420	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
421		sp -= get_random_int() % 8192;
422	return sp & ~0xf;
423}
424#endif
425
426unsigned long get_wchan(struct task_struct *p)
427{
428	unsigned long stack_page, sp, ip;
429	bool seen_sched = 0;
430
431	if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
432		return 0;
433
434	stack_page = (unsigned long) task_stack_page(p);
435	/* Bail if the process has no kernel stack for some reason */
436	if (stack_page == 0)
437		return 0;
438
439	sp = p->thread.switch_buf->JB_SP;
440	/*
441	 * Bail if the stack pointer is below the bottom of the kernel
442	 * stack for some reason
443	 */
444	if (sp < stack_page)
445		return 0;
446
447	while (sp < stack_page + THREAD_SIZE) {
448		ip = *((unsigned long *) sp);
449		if (in_sched_functions(ip))
450			/* Ignore everything until we're above the scheduler */
451			seen_sched = 1;
452		else if (kernel_text_address(ip) && seen_sched)
453			return ip;
454
455		sp += sizeof(unsigned long);
456	}
457
458	return 0;
459}
460
461int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
462{
463	int cpu = current_thread_info()->cpu;
464
465	return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
466}
467

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  4 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  5 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  6 * Copyright 2003 PathScale, Inc.
 
  7 */
  8
  9#include <linux/stddef.h>
 10#include <linux/err.h>
 11#include <linux/hardirq.h>
 12#include <linux/mm.h>
 13#include <linux/module.h>
 14#include <linux/personality.h>
 15#include <linux/proc_fs.h>
 16#include <linux/ptrace.h>
 17#include <linux/random.h>
 18#include <linux/slab.h>
 19#include <linux/sched.h>
 20#include <linux/sched/debug.h>
 21#include <linux/sched/task.h>
 22#include <linux/sched/task_stack.h>
 23#include <linux/seq_file.h>
 24#include <linux/tick.h>
 25#include <linux/threads.h>
 26#include <linux/tracehook.h>
 27#include <asm/current.h>
 
 28#include <asm/mmu_context.h>
 29#include <linux/uaccess.h>
 30#include <as-layout.h>
 31#include <kern_util.h>
 32#include <os.h>
 33#include <skas.h>
 34#include <linux/time-internal.h>
 35
 36/*
 37 * This is a per-cpu array.  A processor only modifies its entry and it only
 38 * cares about its entry, so it's OK if another processor is modifying its
 39 * entry.
 40 */
 41struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
 42
 43static inline int external_pid(void)
 44{
 45	/* FIXME: Need to look up userspace_pid by cpu */
 46	return userspace_pid[0];
 47}
 48
 49int pid_to_processor_id(int pid)
 50{
 51	int i;
 52
 53	for (i = 0; i < ncpus; i++) {
 54		if (cpu_tasks[i].pid == pid)
 55			return i;
 56	}
 57	return -1;
 58}
 59
 60void free_stack(unsigned long stack, int order)
 61{
 62	free_pages(stack, order);
 63}
 64
 65unsigned long alloc_stack(int order, int atomic)
 66{
 67	unsigned long page;
 68	gfp_t flags = GFP_KERNEL;
 69
 70	if (atomic)
 71		flags = GFP_ATOMIC;
 72	page = __get_free_pages(flags, order);
 73
 74	return page;
 75}
 76
 
 
 
 
 
 
 
 
 
 
 
 
 77static inline void set_current(struct task_struct *task)
 78{
 79	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
 80		{ external_pid(), task });
 81}
 82
 83extern void arch_switch_to(struct task_struct *to);
 84
 85void *__switch_to(struct task_struct *from, struct task_struct *to)
 86{
 87	to->thread.prev_sched = from;
 88	set_current(to);
 89
 90	switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
 91	arch_switch_to(current);
 
 
 
 
 
 
 
 
 
 
 
 92
 93	return current->thread.prev_sched;
 94}
 95
 96void interrupt_end(void)
 97{
 98	struct pt_regs *regs = &current->thread.regs;
 99
100	if (need_resched())
101		schedule();
102	if (test_thread_flag(TIF_SIGPENDING) ||
103	    test_thread_flag(TIF_NOTIFY_SIGNAL))
104		do_signal(regs);
105	if (test_thread_flag(TIF_NOTIFY_RESUME))
106		tracehook_notify_resume(regs);
 
 
 
107}
108
109int get_current_pid(void)
110{
111	return task_pid_nr(current);
112}
113
114/*
115 * This is called magically, by its address being stuffed in a jmp_buf
116 * and being longjmp-d to.
117 */
118void new_thread_handler(void)
119{
120	int (*fn)(void *), n;
121	void *arg;
122
123	if (current->thread.prev_sched != NULL)
124		schedule_tail(current->thread.prev_sched);
125	current->thread.prev_sched = NULL;
126
127	fn = current->thread.request.u.thread.proc;
128	arg = current->thread.request.u.thread.arg;
129
130	/*
131	 * callback returns only if the kernel thread execs a process
 
132	 */
133	n = fn(arg);
134	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 
 
 
 
 
135}
136
137/* Called magically, see new_thread_handler above */
138void fork_handler(void)
139{
140	force_flush_all();
141
142	schedule_tail(current->thread.prev_sched);
143
144	/*
145	 * XXX: if interrupt_end() calls schedule, this call to
146	 * arch_switch_to isn't needed. We could want to apply this to
147	 * improve performance. -bb
148	 */
149	arch_switch_to(current);
150
151	current->thread.prev_sched = NULL;
152
153	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 
 
 
154}
155
156int copy_thread(unsigned long clone_flags, unsigned long sp,
157		unsigned long arg, struct task_struct * p, unsigned long tls)
 
158{
159	void (*handler)(void);
160	int kthread = current->flags & (PF_KTHREAD | PF_IO_WORKER);
161	int ret = 0;
162
163	p->thread = (struct thread_struct) INIT_THREAD;
164
165	if (!kthread) {
166	  	memcpy(&p->thread.regs.regs, current_pt_regs(),
167		       sizeof(p->thread.regs.regs));
168		PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
169		if (sp != 0)
170			REGS_SP(p->thread.regs.regs.gp) = sp;
171
172		handler = fork_handler;
173
174		arch_copy_thread(&current->thread.arch, &p->thread.arch);
175	} else {
 
176		get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
177		p->thread.request.u.thread.proc = (int (*)(void *))sp;
178		p->thread.request.u.thread.arg = (void *)arg;
179		handler = new_thread_handler;
180	}
181
182	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
183
184	if (!kthread) {
185		clear_flushed_tls(p);
186
187		/*
188		 * Set a new TLS for the child thread?
189		 */
190		if (clone_flags & CLONE_SETTLS)
191			ret = arch_set_tls(p, tls);
192	}
193
194	return ret;
195}
196
197void initial_thread_cb(void (*proc)(void *), void *arg)
198{
199	int save_kmalloc_ok = kmalloc_ok;
200
201	kmalloc_ok = 0;
202	initial_thread_cb_skas(proc, arg);
203	kmalloc_ok = save_kmalloc_ok;
204}
205
206void um_idle_sleep(void)
207{
208	if (time_travel_mode != TT_MODE_OFF)
209		time_travel_sleep();
210	else
211		os_idle_sleep();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
212}
213
214void arch_cpu_idle(void)
215{
216	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
217	um_idle_sleep();
218	raw_local_irq_enable();
219}
220
221int __cant_sleep(void) {
222	return in_atomic() || irqs_disabled() || in_interrupt();
223	/* Is in_interrupt() really needed? */
224}
225
226int user_context(unsigned long sp)
227{
228	unsigned long stack;
229
230	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
231	return stack != (unsigned long) current_thread_info();
232}
233
234extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
235
236void do_uml_exitcalls(void)
237{
238	exitcall_t *call;
239
240	call = &__uml_exitcall_end;
241	while (--call >= &__uml_exitcall_begin)
242		(*call)();
243}
244
245char *uml_strdup(const char *string)
246{
247	return kstrdup(string, GFP_KERNEL);
248}
249EXPORT_SYMBOL(uml_strdup);
250
251int copy_to_user_proc(void __user *to, void *from, int size)
252{
253	return copy_to_user(to, from, size);
254}
255
256int copy_from_user_proc(void *to, void __user *from, int size)
257{
258	return copy_from_user(to, from, size);
259}
260
261int clear_user_proc(void __user *buf, int size)
262{
263	return clear_user(buf, size);
264}
265
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
266int cpu(void)
267{
268	return current_thread_info()->cpu;
269}
270
271static atomic_t using_sysemu = ATOMIC_INIT(0);
272int sysemu_supported;
273
274void set_using_sysemu(int value)
275{
276	if (value > sysemu_supported)
277		return;
278	atomic_set(&using_sysemu, value);
279}
280
281int get_using_sysemu(void)
282{
283	return atomic_read(&using_sysemu);
284}
285
286static int sysemu_proc_show(struct seq_file *m, void *v)
287{
288	seq_printf(m, "%d\n", get_using_sysemu());
289	return 0;
290}
291
292static int sysemu_proc_open(struct inode *inode, struct file *file)
293{
294	return single_open(file, sysemu_proc_show, NULL);
295}
296
297static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
298				 size_t count, loff_t *pos)
299{
300	char tmp[2];
301
302	if (copy_from_user(tmp, buf, 1))
303		return -EFAULT;
304
305	if (tmp[0] >= '0' && tmp[0] <= '2')
306		set_using_sysemu(tmp[0] - '0');
307	/* We use the first char, but pretend to write everything */
308	return count;
309}
310
311static const struct proc_ops sysemu_proc_ops = {
312	.proc_open	= sysemu_proc_open,
313	.proc_read	= seq_read,
314	.proc_lseek	= seq_lseek,
315	.proc_release	= single_release,
316	.proc_write	= sysemu_proc_write,
 
317};
318
319int __init make_proc_sysemu(void)
320{
321	struct proc_dir_entry *ent;
322	if (!sysemu_supported)
323		return 0;
324
325	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_ops);
326
327	if (ent == NULL)
328	{
329		printk(KERN_WARNING "Failed to register /proc/sysemu\n");
330		return 0;
331	}
332
333	return 0;
334}
335
336late_initcall(make_proc_sysemu);
337
338int singlestepping(void * t)
339{
340	struct task_struct *task = t ? t : current;
341
342	if (!(task->ptrace & PT_DTRACE))
343		return 0;
344
345	if (task->thread.singlestep_syscall)
346		return 1;
347
348	return 2;
349}
350
351/*
352 * Only x86 and x86_64 have an arch_align_stack().
353 * All other arches have "#define arch_align_stack(x) (x)"
354 * in their asm/exec.h
355 * As this is included in UML from asm-um/system-generic.h,
356 * we can use it to behave as the subarch does.
357 */
358#ifndef arch_align_stack
359unsigned long arch_align_stack(unsigned long sp)
360{
361	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
362		sp -= get_random_int() % 8192;
363	return sp & ~0xf;
364}
365#endif
366
367unsigned long get_wchan(struct task_struct *p)
368{
369	unsigned long stack_page, sp, ip;
370	bool seen_sched = 0;
371
372	if ((p == NULL) || (p == current) || task_is_running(p))
373		return 0;
374
375	stack_page = (unsigned long) task_stack_page(p);
376	/* Bail if the process has no kernel stack for some reason */
377	if (stack_page == 0)
378		return 0;
379
380	sp = p->thread.switch_buf->JB_SP;
381	/*
382	 * Bail if the stack pointer is below the bottom of the kernel
383	 * stack for some reason
384	 */
385	if (sp < stack_page)
386		return 0;
387
388	while (sp < stack_page + THREAD_SIZE) {
389		ip = *((unsigned long *) sp);
390		if (in_sched_functions(ip))
391			/* Ignore everything until we're above the scheduler */
392			seen_sched = 1;
393		else if (kernel_text_address(ip) && seen_sched)
394			return ip;
395
396		sp += sizeof(unsigned long);
397	}
398
399	return 0;
400}
401
402int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
403{
404	int cpu = current_thread_info()->cpu;
405
406	return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
407}
408