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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 ([email protected])
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/cpu.h>
19#include <linux/slab.h>
20#include <linux/sched.h>
21#include <linux/sched/debug.h>
22#include <linux/sched/task.h>
23#include <linux/sched/task_stack.h>
24#include <linux/seq_file.h>
25#include <linux/tick.h>
26#include <linux/threads.h>
27#include <linux/resume_user_mode.h>
28#include <asm/current.h>
29#include <asm/mmu_context.h>
30#include <asm/switch_to.h>
31#include <asm/exec.h>
32#include <linux/uaccess.h>
33#include <as-layout.h>
34#include <kern_util.h>
35#include <os.h>
36#include <skas.h>
37#include <registers.h>
38#include <linux/time-internal.h>
39#include <linux/elfcore.h>
40
41/*
42 * This is a per-cpu array. A processor only modifies its entry and it only
43 * cares about its entry, so it's OK if another processor is modifying its
44 * entry.
45 */
46struct task_struct *cpu_tasks[NR_CPUS] = {
47 [0 ... NR_CPUS - 1] = &init_task,
48};
49EXPORT_SYMBOL(cpu_tasks);
50
51void free_stack(unsigned long stack, int order)
52{
53 free_pages(stack, order);
54}
55
56unsigned long alloc_stack(int order, int atomic)
57{
58 unsigned long page;
59 gfp_t flags = GFP_KERNEL;
60
61 if (atomic)
62 flags = GFP_ATOMIC;
63 page = __get_free_pages(flags, order);
64
65 return page;
66}
67
68static inline void set_current(struct task_struct *task)
69{
70 cpu_tasks[task_thread_info(task)->cpu] = task;
71}
72
73struct task_struct *__switch_to(struct task_struct *from, struct task_struct *to)
74{
75 to->thread.prev_sched = from;
76 set_current(to);
77
78 switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
79 arch_switch_to(current);
80
81 return current->thread.prev_sched;
82}
83
84void interrupt_end(void)
85{
86 struct pt_regs *regs = &current->thread.regs;
87 unsigned long thread_flags;
88
89 thread_flags = read_thread_flags();
90 while (thread_flags & _TIF_WORK_MASK) {
91 if (thread_flags & _TIF_NEED_RESCHED)
92 schedule();
93 if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
94 do_signal(regs);
95 if (thread_flags & _TIF_NOTIFY_RESUME)
96 resume_user_mode_work(regs);
97 thread_flags = read_thread_flags();
98 }
99}
100
101int get_current_pid(void)
102{
103 return task_pid_nr(current);
104}
105
106/*
107 * This is called magically, by its address being stuffed in a jmp_buf
108 * and being longjmp-d to.
109 */
110void new_thread_handler(void)
111{
112 int (*fn)(void *);
113 void *arg;
114
115 if (current->thread.prev_sched != NULL)
116 schedule_tail(current->thread.prev_sched);
117 current->thread.prev_sched = NULL;
118
119 fn = current->thread.request.thread.proc;
120 arg = current->thread.request.thread.arg;
121
122 /*
123 * callback returns only if the kernel thread execs a process
124 */
125 fn(arg);
126 userspace(&current->thread.regs.regs);
127}
128
129/* Called magically, see new_thread_handler above */
130static void fork_handler(void)
131{
132 schedule_tail(current->thread.prev_sched);
133
134 /*
135 * XXX: if interrupt_end() calls schedule, this call to
136 * arch_switch_to isn't needed. We could want to apply this to
137 * improve performance. -bb
138 */
139 arch_switch_to(current);
140
141 current->thread.prev_sched = NULL;
142
143 userspace(&current->thread.regs.regs);
144}
145
146int copy_thread(struct task_struct * p, const struct kernel_clone_args *args)
147{
148 u64 clone_flags = args->flags;
149 unsigned long sp = args->stack;
150 unsigned long tls = args->tls;
151 void (*handler)(void);
152 int ret = 0;
153
154 p->thread = (struct thread_struct) INIT_THREAD;
155
156 if (!args->fn) {
157 memcpy(&p->thread.regs.regs, current_pt_regs(),
158 sizeof(p->thread.regs.regs));
159 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
160 if (sp != 0)
161 REGS_SP(p->thread.regs.regs.gp) = sp;
162
163 handler = fork_handler;
164
165 arch_copy_thread(&current->thread.arch, &p->thread.arch);
166 } else {
167 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
168 p->thread.request.thread.proc = args->fn;
169 p->thread.request.thread.arg = args->fn_arg;
170 handler = new_thread_handler;
171 }
172
173 new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
174
175 if (!args->fn) {
176 clear_flushed_tls(p);
177
178 /*
179 * Set a new TLS for the child thread?
180 */
181 if (clone_flags & CLONE_SETTLS)
182 ret = arch_set_tls(p, tls);
183 }
184
185 return ret;
186}
187
188void initial_thread_cb(void (*proc)(void *), void *arg)
189{
190 initial_thread_cb_skas(proc, arg);
191}
192
193int arch_dup_task_struct(struct task_struct *dst,
194 struct task_struct *src)
195{
196 /* init_task is not dynamically sized (missing FPU state) */
197 if (unlikely(src == &init_task)) {
198 memcpy(dst, src, sizeof(init_task));
199 memset((void *)dst + sizeof(init_task), 0,
200 arch_task_struct_size - sizeof(init_task));
201 } else {
202 memcpy(dst, src, arch_task_struct_size);
203 }
204
205 return 0;
206}
207
208void um_idle_sleep(void)
209{
210 if (time_travel_mode != TT_MODE_OFF)
211 time_travel_sleep();
212 else
213 os_idle_sleep();
214}
215
216void arch_cpu_idle(void)
217{
218 um_idle_sleep();
219}
220
221void arch_cpu_idle_prepare(void)
222{
223 os_idle_prepare();
224}
225
226int __uml_cant_sleep(void) {
227 return in_atomic() || irqs_disabled() || in_interrupt();
228 /* Is in_interrupt() really needed? */
229}
230
231int uml_need_resched(void)
232{
233 return need_resched();
234}
235
236extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
237
238void do_uml_exitcalls(void)
239{
240 exitcall_t *call;
241
242 call = &__uml_exitcall_end;
243 while (--call >= &__uml_exitcall_begin)
244 (*call)();
245}
246
247char *uml_strdup(const char *string)
248{
249 return kstrdup(string, GFP_KERNEL);
250}
251EXPORT_SYMBOL(uml_strdup);
252
253int copy_from_user_proc(void *to, void __user *from, int size)
254{
255 return copy_from_user(to, from, size);
256}
257
258int singlestepping(void)
259{
260 return test_thread_flag(TIF_SINGLESTEP);
261}
262
263/*
264 * Only x86 and x86_64 have an arch_align_stack().
265 * All other arches have "#define arch_align_stack(x) (x)"
266 * in their asm/exec.h
267 * As this is included in UML from asm-um/system-generic.h,
268 * we can use it to behave as the subarch does.
269 */
270#ifndef arch_align_stack
271unsigned long arch_align_stack(unsigned long sp)
272{
273 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
274 sp -= get_random_u32_below(8192);
275 return sp & ~0xf;
276}
277#endif
278
279unsigned long __get_wchan(struct task_struct *p)
280{
281 unsigned long stack_page, sp, ip;
282 bool seen_sched = 0;
283
284 stack_page = (unsigned long) task_stack_page(p);
285 /* Bail if the process has no kernel stack for some reason */
286 if (stack_page == 0)
287 return 0;
288
289 sp = p->thread.switch_buf->JB_SP;
290 /*
291 * Bail if the stack pointer is below the bottom of the kernel
292 * stack for some reason
293 */
294 if (sp < stack_page)
295 return 0;
296
297 while (sp < stack_page + THREAD_SIZE) {
298 ip = *((unsigned long *) sp);
299 if (in_sched_functions(ip))
300 /* Ignore everything until we're above the scheduler */
301 seen_sched = 1;
302 else if (kernel_text_address(ip) && seen_sched)
303 return ip;
304
305 sp += sizeof(unsigned long);
306 }
307
308 return 0;
309}