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/pgtable.h>
 29#include <asm/mmu_context.h>
 30#include <linux/uaccess.h>
 31#include <as-layout.h>
 32#include <kern_util.h>
 33#include <os.h>
 34#include <skas.h>
 35#include <timer-internal.h>
 36
 37/*
 38 * This is a per-cpu array.  A processor only modifies its entry and it only
 39 * cares about its entry, so it's OK if another processor is modifying its
 40 * entry.
 41 */
 42struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
 43
 44static inline int external_pid(void)
 45{
 46	/* FIXME: Need to look up userspace_pid by cpu */
 47	return userspace_pid[0];
 48}
 49
 50int pid_to_processor_id(int pid)
 51{
 52	int i;
 53
 54	for (i = 0; i < ncpus; i++) {
 55		if (cpu_tasks[i].pid == pid)
 56			return i;
 57	}
 58	return -1;
 59}
 60
 61void free_stack(unsigned long stack, int order)
 62{
 63	free_pages(stack, order);
 64}
 65
 66unsigned long alloc_stack(int order, int atomic)
 67{
 68	unsigned long page;
 69	gfp_t flags = GFP_KERNEL;
 70
 71	if (atomic)
 72		flags = GFP_ATOMIC;
 73	page = __get_free_pages(flags, order);
 74
 75	return page;
 76}
 77
 78static inline void set_current(struct task_struct *task)
 79{
 80	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
 81		{ external_pid(), task });
 82}
 83
 84extern void arch_switch_to(struct task_struct *to);
 85
 86void *__switch_to(struct task_struct *from, struct task_struct *to)
 87{
 88	to->thread.prev_sched = from;
 89	set_current(to);
 90
 91	switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
 92	arch_switch_to(current);
 93
 94	return current->thread.prev_sched;
 95}
 96
 97void interrupt_end(void)
 98{
 99	struct pt_regs *regs = &current->thread.regs;
100
101	if (need_resched())
102		schedule();
103	if (test_thread_flag(TIF_SIGPENDING))
104		do_signal(regs);
105	if (test_and_clear_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)
158{
159	void (*handler)(void);
160	int kthread = current->flags & PF_KTHREAD;
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_copy_tls(p);
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
206static void time_travel_sleep(unsigned long long duration)
207{
208	unsigned long long next = time_travel_time + duration;
209
210	if (time_travel_mode != TT_MODE_INFCPU)
211		os_timer_disable();
212
213	while (time_travel_timer_mode == TT_TMR_PERIODIC &&
214	       time_travel_timer_expiry < time_travel_time)
215		time_travel_set_timer_expiry(time_travel_timer_expiry +
216					     time_travel_timer_interval);
217
218	if (time_travel_timer_mode != TT_TMR_DISABLED &&
219	    time_travel_timer_expiry < next) {
220		if (time_travel_timer_mode == TT_TMR_ONESHOT)
221			time_travel_set_timer_mode(TT_TMR_DISABLED);
222		/*
223		 * In basic mode, time_travel_time will be adjusted in
224		 * the timer IRQ handler so it works even when the signal
225		 * comes from the OS timer, see there.
226		 */
227		if (time_travel_mode != TT_MODE_BASIC)
228			time_travel_set_time(time_travel_timer_expiry);
229
230		deliver_alarm();
231	} else {
232		time_travel_set_time(next);
233	}
234
235	if (time_travel_mode != TT_MODE_INFCPU) {
236		if (time_travel_timer_mode == TT_TMR_PERIODIC)
237			os_timer_set_interval(time_travel_timer_interval);
238		else if (time_travel_timer_mode == TT_TMR_ONESHOT)
239			os_timer_one_shot(time_travel_timer_expiry - next);
240	}
241}
242
243static void um_idle_sleep(void)
244{
245	unsigned long long duration = UM_NSEC_PER_SEC;
246
247	if (time_travel_mode != TT_MODE_OFF) {
248		time_travel_sleep(duration);
249	} else {
250		os_idle_sleep(duration);
251	}
252}
253
254void arch_cpu_idle(void)
255{
256	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
257	um_idle_sleep();
258	local_irq_enable();
259}
260
261int __cant_sleep(void) {
262	return in_atomic() || irqs_disabled() || in_interrupt();
263	/* Is in_interrupt() really needed? */
264}
265
266int user_context(unsigned long sp)
267{
268	unsigned long stack;
269
270	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
271	return stack != (unsigned long) current_thread_info();
272}
273
274extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
275
276void do_uml_exitcalls(void)
277{
278	exitcall_t *call;
279
280	call = &__uml_exitcall_end;
281	while (--call >= &__uml_exitcall_begin)
282		(*call)();
283}
284
285char *uml_strdup(const char *string)
286{
287	return kstrdup(string, GFP_KERNEL);
288}
289EXPORT_SYMBOL(uml_strdup);
290
291int copy_to_user_proc(void __user *to, void *from, int size)
292{
293	return copy_to_user(to, from, size);
294}
295
296int copy_from_user_proc(void *to, void __user *from, int size)
297{
298	return copy_from_user(to, from, size);
299}
300
301int clear_user_proc(void __user *buf, int size)
302{
303	return clear_user(buf, size);
 
 
 
 
 
304}
305
306int cpu(void)
307{
308	return current_thread_info()->cpu;
309}
310
311static atomic_t using_sysemu = ATOMIC_INIT(0);
312int sysemu_supported;
313
314void set_using_sysemu(int value)
315{
316	if (value > sysemu_supported)
317		return;
318	atomic_set(&using_sysemu, value);
319}
320
321int get_using_sysemu(void)
322{
323	return atomic_read(&using_sysemu);
324}
325
326static int sysemu_proc_show(struct seq_file *m, void *v)
327{
328	seq_printf(m, "%d\n", get_using_sysemu());
329	return 0;
330}
331
332static int sysemu_proc_open(struct inode *inode, struct file *file)
333{
334	return single_open(file, sysemu_proc_show, NULL);
335}
336
337static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
338				 size_t count, loff_t *pos)
339{
340	char tmp[2];
341
342	if (copy_from_user(tmp, buf, 1))
343		return -EFAULT;
344
345	if (tmp[0] >= '0' && tmp[0] <= '2')
346		set_using_sysemu(tmp[0] - '0');
347	/* We use the first char, but pretend to write everything */
348	return count;
349}
350
351static const struct file_operations sysemu_proc_fops = {
352	.owner		= THIS_MODULE,
353	.open		= sysemu_proc_open,
354	.read		= seq_read,
355	.llseek		= seq_lseek,
356	.release	= single_release,
357	.write		= sysemu_proc_write,
358};
359
360int __init make_proc_sysemu(void)
361{
362	struct proc_dir_entry *ent;
363	if (!sysemu_supported)
364		return 0;
365
366	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
367
368	if (ent == NULL)
369	{
370		printk(KERN_WARNING "Failed to register /proc/sysemu\n");
371		return 0;
372	}
373
374	return 0;
375}
376
377late_initcall(make_proc_sysemu);
378
379int singlestepping(void * t)
380{
381	struct task_struct *task = t ? t : current;
382
383	if (!(task->ptrace & PT_DTRACE))
384		return 0;
385
386	if (task->thread.singlestep_syscall)
387		return 1;
388
389	return 2;
390}
391
392/*
393 * Only x86 and x86_64 have an arch_align_stack().
394 * All other arches have "#define arch_align_stack(x) (x)"
395 * in their asm/exec.h
396 * As this is included in UML from asm-um/system-generic.h,
397 * we can use it to behave as the subarch does.
398 */
399#ifndef arch_align_stack
400unsigned long arch_align_stack(unsigned long sp)
401{
402	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
403		sp -= get_random_int() % 8192;
404	return sp & ~0xf;
405}
406#endif
407
408unsigned long get_wchan(struct task_struct *p)
409{
410	unsigned long stack_page, sp, ip;
411	bool seen_sched = 0;
412
413	if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
414		return 0;
415
416	stack_page = (unsigned long) task_stack_page(p);
417	/* Bail if the process has no kernel stack for some reason */
418	if (stack_page == 0)
419		return 0;
420
421	sp = p->thread.switch_buf->JB_SP;
422	/*
423	 * Bail if the stack pointer is below the bottom of the kernel
424	 * stack for some reason
425	 */
426	if (sp < stack_page)
427		return 0;
428
429	while (sp < stack_page + THREAD_SIZE) {
430		ip = *((unsigned long *) sp);
431		if (in_sched_functions(ip))
432			/* Ignore everything until we're above the scheduler */
433			seen_sched = 1;
434		else if (kernel_text_address(ip) && seen_sched)
435			return ip;
436
437		sp += sizeof(unsigned long);
438	}
439
440	return 0;
441}
442
443int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
444{
445	int cpu = current_thread_info()->cpu;
446
447	return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
448}
449

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