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
72static inline void set_current(struct task_struct *task)
73{
74	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
75		{ external_pid(), task });
76}
77
78extern void arch_switch_to(struct task_struct *to);
79
80void *__switch_to(struct task_struct *from, struct task_struct *to)
81{
82	to->thread.prev_sched = from;
83	set_current(to);
84
85	switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
86	arch_switch_to(current);
87
88	return current->thread.prev_sched;
89}
90
91void interrupt_end(void)
92{
93	if (need_resched())
94		schedule();
95	if (test_thread_flag(TIF_SIGPENDING))
96		do_signal();
97	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
98		tracehook_notify_resume(&current->thread.regs);
99}
100
101void exit_thread(void)
102{
103}
104
105int get_current_pid(void)
106{
107	return task_pid_nr(current);
108}
109
110/*
111 * This is called magically, by its address being stuffed in a jmp_buf
112 * and being longjmp-d to.
113 */
114void new_thread_handler(void)
115{
116	int (*fn)(void *), n;
117	void *arg;
118
119	if (current->thread.prev_sched != NULL)
120		schedule_tail(current->thread.prev_sched);
121	current->thread.prev_sched = NULL;
122
123	fn = current->thread.request.u.thread.proc;
124	arg = current->thread.request.u.thread.arg;
125
126	/*
127	 * callback returns only if the kernel thread execs a process
128	 */
129	n = fn(arg);
130	userspace(&current->thread.regs.regs);
131}
132
133/* Called magically, see new_thread_handler above */
134void fork_handler(void)
135{
136	force_flush_all();
137
138	schedule_tail(current->thread.prev_sched);
139
140	/*
141	 * XXX: if interrupt_end() calls schedule, this call to
142	 * arch_switch_to isn't needed. We could want to apply this to
143	 * improve performance. -bb
144	 */
145	arch_switch_to(current);
146
147	current->thread.prev_sched = NULL;
148
149	userspace(&current->thread.regs.regs);
150}
151
152int copy_thread(unsigned long clone_flags, unsigned long sp,
153		unsigned long arg, struct task_struct * p)
154{
155	void (*handler)(void);
156	int kthread = current->flags & PF_KTHREAD;
157	int ret = 0;
158
159	p->thread = (struct thread_struct) INIT_THREAD;
160
161	if (!kthread) {
162	  	memcpy(&p->thread.regs.regs, current_pt_regs(),
163		       sizeof(p->thread.regs.regs));
164		PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
165		if (sp != 0)
166			REGS_SP(p->thread.regs.regs.gp) = sp;
167
168		handler = fork_handler;
169
170		arch_copy_thread(&current->thread.arch, &p->thread.arch);
171	} else {
172		get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
173		p->thread.request.u.thread.proc = (int (*)(void *))sp;
174		p->thread.request.u.thread.arg = (void *)arg;
175		handler = new_thread_handler;
176	}
177
178	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
179
180	if (!kthread) {
181		clear_flushed_tls(p);
182
183		/*
184		 * Set a new TLS for the child thread?
185		 */
186		if (clone_flags & CLONE_SETTLS)
187			ret = arch_copy_tls(p);
188	}
189
190	return ret;
191}
192
193void initial_thread_cb(void (*proc)(void *), void *arg)
194{
195	int save_kmalloc_ok = kmalloc_ok;
196
197	kmalloc_ok = 0;
198	initial_thread_cb_skas(proc, arg);
199	kmalloc_ok = save_kmalloc_ok;
200}
201
202void arch_cpu_idle(void)
203{
204	unsigned long long nsecs;
205
206	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
207	nsecs = disable_timer();
208	idle_sleep(nsecs);
209	local_irq_enable();
210}
211
212int __cant_sleep(void) {
213	return in_atomic() || irqs_disabled() || in_interrupt();
214	/* Is in_interrupt() really needed? */
215}
216
217int user_context(unsigned long sp)
218{
219	unsigned long stack;
220
221	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
222	return stack != (unsigned long) current_thread_info();
223}
224
225extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
226
227void do_uml_exitcalls(void)
228{
229	exitcall_t *call;
230
231	call = &__uml_exitcall_end;
232	while (--call >= &__uml_exitcall_begin)
233		(*call)();
234}
235
236char *uml_strdup(const char *string)
237{
238	return kstrdup(string, GFP_KERNEL);
239}
240EXPORT_SYMBOL(uml_strdup);
241
242int copy_to_user_proc(void __user *to, void *from, int size)
243{
244	return copy_to_user(to, from, size);
245}
246
247int copy_from_user_proc(void *to, void __user *from, int size)
248{
249	return copy_from_user(to, from, size);
250}
251
252int clear_user_proc(void __user *buf, int size)
253{
254	return clear_user(buf, size);
255}
256
257int strlen_user_proc(char __user *str)
258{
259	return strlen_user(str);
260}
261
262int cpu(void)
263{
264	return current_thread_info()->cpu;
265}
266
267static atomic_t using_sysemu = ATOMIC_INIT(0);
268int sysemu_supported;
269
270void set_using_sysemu(int value)
271{
272	if (value > sysemu_supported)
273		return;
274	atomic_set(&using_sysemu, value);
275}
276
277int get_using_sysemu(void)
278{
279	return atomic_read(&using_sysemu);
280}
281
282static int sysemu_proc_show(struct seq_file *m, void *v)
283{
284	seq_printf(m, "%d\n", get_using_sysemu());
285	return 0;
286}
287
288static int sysemu_proc_open(struct inode *inode, struct file *file)
289{
290	return single_open(file, sysemu_proc_show, NULL);
291}
292
293static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
294				 size_t count, loff_t *pos)
295{
296	char tmp[2];
297
298	if (copy_from_user(tmp, buf, 1))
299		return -EFAULT;
300
301	if (tmp[0] >= '0' && tmp[0] <= '2')
302		set_using_sysemu(tmp[0] - '0');
303	/* We use the first char, but pretend to write everything */
304	return count;
305}
306
307static const struct file_operations sysemu_proc_fops = {
308	.owner		= THIS_MODULE,
309	.open		= sysemu_proc_open,
310	.read		= seq_read,
311	.llseek		= seq_lseek,
312	.release	= single_release,
313	.write		= sysemu_proc_write,
314};
315
316int __init make_proc_sysemu(void)
317{
318	struct proc_dir_entry *ent;
319	if (!sysemu_supported)
320		return 0;
321
322	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
323
324	if (ent == NULL)
325	{
326		printk(KERN_WARNING "Failed to register /proc/sysemu\n");
327		return 0;
328	}
329
330	return 0;
331}
332
333late_initcall(make_proc_sysemu);
334
335int singlestepping(void * t)
336{
337	struct task_struct *task = t ? t : current;
338
339	if (!(task->ptrace & PT_DTRACE))
340		return 0;
341
342	if (task->thread.singlestep_syscall)
343		return 1;
344
345	return 2;
346}
347
348/*
349 * Only x86 and x86_64 have an arch_align_stack().
350 * All other arches have "#define arch_align_stack(x) (x)"
351 * in their asm/exec.h
352 * As this is included in UML from asm-um/system-generic.h,
353 * we can use it to behave as the subarch does.
354 */
355#ifndef arch_align_stack
356unsigned long arch_align_stack(unsigned long sp)
357{
358	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
359		sp -= get_random_int() % 8192;
360	return sp & ~0xf;
361}
362#endif
363
364unsigned long get_wchan(struct task_struct *p)
365{
366	unsigned long stack_page, sp, ip;
367	bool seen_sched = 0;
368
369	if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
370		return 0;
371
372	stack_page = (unsigned long) task_stack_page(p);
373	/* Bail if the process has no kernel stack for some reason */
374	if (stack_page == 0)
375		return 0;
376
377	sp = p->thread.switch_buf->JB_SP;
378	/*
379	 * Bail if the stack pointer is below the bottom of the kernel
380	 * stack for some reason
381	 */
382	if (sp < stack_page)
383		return 0;
384
385	while (sp < stack_page + THREAD_SIZE) {
386		ip = *((unsigned long *) sp);
387		if (in_sched_functions(ip))
388			/* Ignore everything until we're above the scheduler */
389			seen_sched = 1;
390		else if (kernel_text_address(ip) && seen_sched)
391			return ip;
392
393		sp += sizeof(unsigned long);
394	}
395
396	return 0;
397}
398
399int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
400{
401	int cpu = current_thread_info()->cpu;
402
403	return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
404}
405
406