xref: /openbmc/linux/arch/s390/kernel/process.c (revision 64c70b1c) 
1 /*
2  *  arch/s390/kernel/process.c
3  *
4  *  S390 version
5  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
7  *               Hartmut Penner (hp@de.ibm.com),
8  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
9  *
10  *  Derived from "arch/i386/kernel/process.c"
11  *    Copyright (C) 1995, Linus Torvalds
12  */
13 
14 /*
15  * This file handles the architecture-dependent parts of process handling..
16  */
17 
18 #include <linux/compiler.h>
19 #include <linux/cpu.h>
20 #include <linux/errno.h>
21 #include <linux/sched.h>
22 #include <linux/kernel.h>
23 #include <linux/mm.h>
24 #include <linux/smp.h>
25 #include <linux/stddef.h>
26 #include <linux/unistd.h>
27 #include <linux/ptrace.h>
28 #include <linux/slab.h>
29 #include <linux/vmalloc.h>
30 #include <linux/user.h>
31 #include <linux/a.out.h>
32 #include <linux/interrupt.h>
33 #include <linux/delay.h>
34 #include <linux/reboot.h>
35 #include <linux/init.h>
36 #include <linux/module.h>
37 #include <linux/notifier.h>
38 
39 #include <asm/uaccess.h>
40 #include <asm/pgtable.h>
41 #include <asm/system.h>
42 #include <asm/io.h>
43 #include <asm/processor.h>
44 #include <asm/irq.h>
45 #include <asm/timer.h>
46 
47 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
48 
49 /*
50  * Return saved PC of a blocked thread. used in kernel/sched.
51  * resume in entry.S does not create a new stack frame, it
52  * just stores the registers %r6-%r15 to the frame given by
53  * schedule. We want to return the address of the caller of
54  * schedule, so we have to walk the backchain one time to
55  * find the frame schedule() store its return address.
56  */
57 unsigned long thread_saved_pc(struct task_struct *tsk)
58 {
59 	struct stack_frame *sf, *low, *high;
60 
61 	if (!tsk || !task_stack_page(tsk))
62 		return 0;
63 	low = task_stack_page(tsk);
64 	high = (struct stack_frame *) task_pt_regs(tsk);
65 	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
66 	if (sf <= low || sf > high)
67 		return 0;
68 	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
69 	if (sf <= low || sf > high)
70 		return 0;
71 	return sf->gprs[8];
72 }
73 
74 /*
75  * Need to know about CPUs going idle?
76  */
77 static ATOMIC_NOTIFIER_HEAD(idle_chain);
78 
79 int register_idle_notifier(struct notifier_block *nb)
80 {
81 	return atomic_notifier_chain_register(&idle_chain, nb);
82 }
83 EXPORT_SYMBOL(register_idle_notifier);
84 
85 int unregister_idle_notifier(struct notifier_block *nb)
86 {
87 	return atomic_notifier_chain_unregister(&idle_chain, nb);
88 }
89 EXPORT_SYMBOL(unregister_idle_notifier);
90 
91 void do_monitor_call(struct pt_regs *regs, long interruption_code)
92 {
93 	/* disable monitor call class 0 */
94 	__ctl_clear_bit(8, 15);
95 
96 	atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
97 				   (void *)(long) smp_processor_id());
98 }
99 
100 extern void s390_handle_mcck(void);
101 /*
102  * The idle loop on a S390...
103  */
104 static void default_idle(void)
105 {
106 	int cpu, rc;
107 
108 	/* CPU is going idle. */
109 	cpu = smp_processor_id();
110 
111 	local_irq_disable();
112 	if (need_resched()) {
113 		local_irq_enable();
114 		return;
115 	}
116 
117 	rc = atomic_notifier_call_chain(&idle_chain,
118 					S390_CPU_IDLE, (void *)(long) cpu);
119 	if (rc != NOTIFY_OK && rc != NOTIFY_DONE)
120 		BUG();
121 	if (rc != NOTIFY_OK) {
122 		local_irq_enable();
123 		return;
124 	}
125 
126 	/* enable monitor call class 0 */
127 	__ctl_set_bit(8, 15);
128 
129 #ifdef CONFIG_HOTPLUG_CPU
130 	if (cpu_is_offline(cpu)) {
131 		preempt_enable_no_resched();
132 		cpu_die();
133 	}
134 #endif
135 
136 	local_mcck_disable();
137 	if (test_thread_flag(TIF_MCCK_PENDING)) {
138 		local_mcck_enable();
139 		local_irq_enable();
140 		s390_handle_mcck();
141 		return;
142 	}
143 
144 	trace_hardirqs_on();
145 	/* Wait for external, I/O or machine check interrupt. */
146 	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
147 			PSW_MASK_IO | PSW_MASK_EXT);
148 }
149 
150 void cpu_idle(void)
151 {
152 	for (;;) {
153 		while (!need_resched())
154 			default_idle();
155 
156 		preempt_enable_no_resched();
157 		schedule();
158 		preempt_disable();
159 	}
160 }
161 
162 void show_regs(struct pt_regs *regs)
163 {
164 	struct task_struct *tsk = current;
165 
166         printk("CPU:    %d    %s\n", task_thread_info(tsk)->cpu, print_tainted());
167         printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
168 	       current->comm, current->pid, (void *) tsk,
169 	       (void *) tsk->thread.ksp);
170 
171 	show_registers(regs);
172 	/* Show stack backtrace if pt_regs is from kernel mode */
173 	if (!(regs->psw.mask & PSW_MASK_PSTATE))
174 		show_trace(NULL, (unsigned long *) regs->gprs[15]);
175 }
176 
177 extern void kernel_thread_starter(void);
178 
179 asm(
180 	".align 4\n"
181 	"kernel_thread_starter:\n"
182 	"    la    2,0(10)\n"
183 	"    basr  14,9\n"
184 	"    la    2,0\n"
185 	"    br    11\n");
186 
187 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
188 {
189 	struct pt_regs regs;
190 
191 	memset(&regs, 0, sizeof(regs));
192 	regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
193 	regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
194 	regs.gprs[9] = (unsigned long) fn;
195 	regs.gprs[10] = (unsigned long) arg;
196 	regs.gprs[11] = (unsigned long) do_exit;
197 	regs.orig_gpr2 = -1;
198 
199 	/* Ok, create the new process.. */
200 	return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
201 		       0, &regs, 0, NULL, NULL);
202 }
203 
204 /*
205  * Free current thread data structures etc..
206  */
207 void exit_thread(void)
208 {
209 }
210 
211 void flush_thread(void)
212 {
213 	clear_used_math();
214 	clear_tsk_thread_flag(current, TIF_USEDFPU);
215 }
216 
217 void release_thread(struct task_struct *dead_task)
218 {
219 }
220 
221 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
222 	unsigned long unused,
223         struct task_struct * p, struct pt_regs * regs)
224 {
225         struct fake_frame
226           {
227 	    struct stack_frame sf;
228             struct pt_regs childregs;
229           } *frame;
230 
231         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
232         p->thread.ksp = (unsigned long) frame;
233 	/* Store access registers to kernel stack of new process. */
234         frame->childregs = *regs;
235 	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
236         frame->childregs.gprs[15] = new_stackp;
237         frame->sf.back_chain = 0;
238 
239         /* new return point is ret_from_fork */
240         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
241 
242         /* fake return stack for resume(), don't go back to schedule */
243         frame->sf.gprs[9] = (unsigned long) frame;
244 
245 	/* Save access registers to new thread structure. */
246 	save_access_regs(&p->thread.acrs[0]);
247 
248 #ifndef CONFIG_64BIT
249         /*
250 	 * save fprs to current->thread.fp_regs to merge them with
251 	 * the emulated registers and then copy the result to the child.
252 	 */
253 	save_fp_regs(&current->thread.fp_regs);
254 	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
255 	       sizeof(s390_fp_regs));
256         p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _SEGMENT_TABLE;
257 	/* Set a new TLS ?  */
258 	if (clone_flags & CLONE_SETTLS)
259 		p->thread.acrs[0] = regs->gprs[6];
260 #else /* CONFIG_64BIT */
261 	/* Save the fpu registers to new thread structure. */
262 	save_fp_regs(&p->thread.fp_regs);
263         p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _REGION_TABLE;
264 	/* Set a new TLS ?  */
265 	if (clone_flags & CLONE_SETTLS) {
266 		if (test_thread_flag(TIF_31BIT)) {
267 			p->thread.acrs[0] = (unsigned int) regs->gprs[6];
268 		} else {
269 			p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
270 			p->thread.acrs[1] = (unsigned int) regs->gprs[6];
271 		}
272 	}
273 #endif /* CONFIG_64BIT */
274 	/* start new process with ar4 pointing to the correct address space */
275 	p->thread.mm_segment = get_fs();
276         /* Don't copy debug registers */
277         memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
278 
279         return 0;
280 }
281 
282 asmlinkage long sys_fork(void)
283 {
284 	struct pt_regs *regs = task_pt_regs(current);
285 	return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
286 }
287 
288 asmlinkage long sys_clone(void)
289 {
290 	struct pt_regs *regs = task_pt_regs(current);
291 	unsigned long clone_flags;
292 	unsigned long newsp;
293 	int __user *parent_tidptr, *child_tidptr;
294 
295 	clone_flags = regs->gprs[3];
296 	newsp = regs->orig_gpr2;
297 	parent_tidptr = (int __user *) regs->gprs[4];
298 	child_tidptr = (int __user *) regs->gprs[5];
299 	if (!newsp)
300 		newsp = regs->gprs[15];
301 	return do_fork(clone_flags, newsp, regs, 0,
302 		       parent_tidptr, child_tidptr);
303 }
304 
305 /*
306  * This is trivial, and on the face of it looks like it
307  * could equally well be done in user mode.
308  *
309  * Not so, for quite unobvious reasons - register pressure.
310  * In user mode vfork() cannot have a stack frame, and if
311  * done by calling the "clone()" system call directly, you
312  * do not have enough call-clobbered registers to hold all
313  * the information you need.
314  */
315 asmlinkage long sys_vfork(void)
316 {
317 	struct pt_regs *regs = task_pt_regs(current);
318 	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
319 		       regs->gprs[15], regs, 0, NULL, NULL);
320 }
321 
322 asmlinkage void execve_tail(void)
323 {
324 	task_lock(current);
325 	current->ptrace &= ~PT_DTRACE;
326 	task_unlock(current);
327 	current->thread.fp_regs.fpc = 0;
328 	if (MACHINE_HAS_IEEE)
329 		asm volatile("sfpc %0,%0" : : "d" (0));
330 }
331 
332 /*
333  * sys_execve() executes a new program.
334  */
335 asmlinkage long sys_execve(void)
336 {
337 	struct pt_regs *regs = task_pt_regs(current);
338 	char *filename;
339 	unsigned long result;
340 	int rc;
341 
342 	filename = getname((char __user *) regs->orig_gpr2);
343 	if (IS_ERR(filename)) {
344 		result = PTR_ERR(filename);
345 		goto out;
346 	}
347 	rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
348 		       (char __user * __user *) regs->gprs[4], regs);
349 	if (rc) {
350 		result = rc;
351 		goto out_putname;
352 	}
353 	execve_tail();
354 	result = regs->gprs[2];
355 out_putname:
356 	putname(filename);
357 out:
358 	return result;
359 }
360 
361 /*
362  * fill in the FPU structure for a core dump.
363  */
364 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
365 {
366 #ifndef CONFIG_64BIT
367         /*
368 	 * save fprs to current->thread.fp_regs to merge them with
369 	 * the emulated registers and then copy the result to the dump.
370 	 */
371 	save_fp_regs(&current->thread.fp_regs);
372 	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
373 #else /* CONFIG_64BIT */
374 	save_fp_regs(fpregs);
375 #endif /* CONFIG_64BIT */
376 	return 1;
377 }
378 
379 unsigned long get_wchan(struct task_struct *p)
380 {
381 	struct stack_frame *sf, *low, *high;
382 	unsigned long return_address;
383 	int count;
384 
385 	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
386 		return 0;
387 	low = task_stack_page(p);
388 	high = (struct stack_frame *) task_pt_regs(p);
389 	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
390 	if (sf <= low || sf > high)
391 		return 0;
392 	for (count = 0; count < 16; count++) {
393 		sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
394 		if (sf <= low || sf > high)
395 			return 0;
396 		return_address = sf->gprs[8] & PSW_ADDR_INSN;
397 		if (!in_sched_functions(return_address))
398 			return return_address;
399 	}
400 	return 0;
401 }
402 
403