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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  */
41 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
42 
external_pid(void)43 static inline int external_pid(void)
44 {
45 	/* FIXME: Need to look up userspace_pid by cpu */
46 	return userspace_pid[0];
47 }
48 
pid_to_processor_id(int pid)49 int 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 
free_stack(unsigned long stack,int order)60 void free_stack(unsigned long stack, int order)
61 {
62 	free_pages(stack, order);
63 }
64 
alloc_stack(int order,int atomic)65 unsigned 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 
set_current(struct task_struct * task)77 static 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 
83 extern void arch_switch_to(struct task_struct *to);
84 
__switch_to(struct task_struct * from,struct task_struct * to)85 void *__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 
interrupt_end(void)96 void 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 
get_current_pid(void)109 int 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  */
new_thread_handler(void)118 void 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 */
fork_handler(void)138 void 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 
copy_thread(unsigned long clone_flags,unsigned long sp,unsigned long arg,struct task_struct * p,unsigned long tls)156 int 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 
initial_thread_cb(void (* proc)(void *),void * arg)197 void 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 
um_idle_sleep(void)206 void 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 
arch_cpu_idle(void)214 void 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 
__uml_cant_sleep(void)221 int __uml_cant_sleep(void) {
222 	return in_atomic() || irqs_disabled() || in_interrupt();
223 	/* Is in_interrupt() really needed? */
224 }
225 
user_context(unsigned long sp)226 int 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 
234 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
235 
do_uml_exitcalls(void)236 void 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 
uml_strdup(const char * string)245 char *uml_strdup(const char *string)
246 {
247 	return kstrdup(string, GFP_KERNEL);
248 }
249 EXPORT_SYMBOL(uml_strdup);
250 
copy_to_user_proc(void __user * to,void * from,int size)251 int copy_to_user_proc(void __user *to, void *from, int size)
252 {
253 	return copy_to_user(to, from, size);
254 }
255 
copy_from_user_proc(void * to,void __user * from,int size)256 int copy_from_user_proc(void *to, void __user *from, int size)
257 {
258 	return copy_from_user(to, from, size);
259 }
260 
clear_user_proc(void __user * buf,int size)261 int clear_user_proc(void __user *buf, int size)
262 {
263 	return clear_user(buf, size);
264 }
265 
cpu(void)266 int cpu(void)
267 {
268 	return current_thread_info()->cpu;
269 }
270 
271 static atomic_t using_sysemu = ATOMIC_INIT(0);
272 int sysemu_supported;
273 
set_using_sysemu(int value)274 void set_using_sysemu(int value)
275 {
276 	if (value > sysemu_supported)
277 		return;
278 	atomic_set(&using_sysemu, value);
279 }
280 
get_using_sysemu(void)281 int get_using_sysemu(void)
282 {
283 	return atomic_read(&using_sysemu);
284 }
285 
sysemu_proc_show(struct seq_file * m,void * v)286 static 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 
sysemu_proc_open(struct inode * inode,struct file * file)292 static int sysemu_proc_open(struct inode *inode, struct file *file)
293 {
294 	return single_open(file, sysemu_proc_show, NULL);
295 }
296 
sysemu_proc_write(struct file * file,const char __user * buf,size_t count,loff_t * pos)297 static 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 
311 static 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 
make_proc_sysemu(void)319 int __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 
336 late_initcall(make_proc_sysemu);
337 
singlestepping(void * t)338 int singlestepping(void * t)
339 {
340 	struct task_struct *task = t ? t : current;
341 
342 	if (!test_thread_flag(TIF_SINGLESTEP))
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
arch_align_stack(unsigned long sp)359 unsigned 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 
get_wchan(struct task_struct * p)367 unsigned 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 
elf_core_copy_fpregs(struct task_struct * t,elf_fpregset_t * fpu)402 int 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 
409