/arch/s390/kernel/process.c

  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/config.h>
 19#include <linux/compiler.h>
 20#include <linux/cpu.h>
 21#include <linux/errno.h>
 22#include <linux/sched.h>
 23#include <linux/kernel.h>
 24#include <linux/mm.h>
 25#include <linux/smp.h>
 26#include <linux/smp_lock.h>
 27#include <linux/stddef.h>
 28#include <linux/unistd.h>
 29#include <linux/ptrace.h>
 30#include <linux/slab.h>
 31#include <linux/vmalloc.h>
 32#include <linux/user.h>
 33#include <linux/a.out.h>
 34#include <linux/interrupt.h>
 35#include <linux/delay.h>
 36#include <linux/reboot.h>
 37#include <linux/init.h>
 38#include <linux/module.h>
 39#include <linux/notifier.h>
 40
 41#include <asm/uaccess.h>
 42#include <asm/pgtable.h>
 43#include <asm/system.h>
 44#include <asm/io.h>
 45#include <asm/processor.h>
 46#include <asm/irq.h>
 47#include <asm/timer.h>
 48
 49asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 50
 51/*
 52 * Return saved PC of a blocked thread. used in kernel/sched.
 53 * resume in entry.S does not create a new stack frame, it
 54 * just stores the registers %r6-%r15 to the frame given by
 55 * schedule. We want to return the address of the caller of
 56 * schedule, so we have to walk the backchain one time to
 57 * find the frame schedule() store its return address.
 58 */
 59unsigned long thread_saved_pc(struct task_struct *tsk)
 60{
 61	struct stack_frame *sf;
 62
 63	sf = (struct stack_frame *) tsk->thread.ksp;
 64	sf = (struct stack_frame *) sf->back_chain;
 65	return sf->gprs[8];
 66}
 67
 68/*
 69 * Need to know about CPUs going idle?
 70 */
 71static struct notifier_block *idle_chain;
 72
 73int register_idle_notifier(struct notifier_block *nb)
 74{
 75	return notifier_chain_register(&idle_chain, nb);
 76}
 77EXPORT_SYMBOL(register_idle_notifier);
 78
 79int unregister_idle_notifier(struct notifier_block *nb)
 80{
 81	return notifier_chain_unregister(&idle_chain, nb);
 82}
 83EXPORT_SYMBOL(unregister_idle_notifier);
 84
 85void do_monitor_call(struct pt_regs *regs, long interruption_code)
 86{
 87	/* disable monitor call class 0 */
 88	__ctl_clear_bit(8, 15);
 89
 90	notifier_call_chain(&idle_chain, CPU_NOT_IDLE,
 91			    (void *)(long) smp_processor_id());
 92}
 93
 94/*
 95 * The idle loop on a S390...
 96 */
 97void default_idle(void)
 98{
 99	psw_t wait_psw;
100	unsigned long reg;
101	int cpu, rc;
102
103	local_irq_disable();
104        if (need_resched()) {
105		local_irq_enable();
106                schedule();
107                return;
108        }
109
110	/* CPU is going idle. */
111	cpu = smp_processor_id();
112	rc = notifier_call_chain(&idle_chain, CPU_IDLE, (void *)(long) cpu);
113	if (rc != NOTIFY_OK && rc != NOTIFY_DONE)
114		BUG();
115	if (rc != NOTIFY_OK) {
116		local_irq_enable();
117		return;
118	}
119
120	/* enable monitor call class 0 */
121	__ctl_set_bit(8, 15);
122
123#ifdef CONFIG_HOTPLUG_CPU
124	if (cpu_is_offline(smp_processor_id()))
125		cpu_die();
126#endif
127
128	/* 
129	 * Wait for external, I/O or machine check interrupt and
130	 * switch off machine check bit after the wait has ended.
131	 */
132	wait_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK | PSW_MASK_WAIT |
133		PSW_MASK_IO | PSW_MASK_EXT;
134#ifndef CONFIG_ARCH_S390X
135	asm volatile (
136		"    basr %0,0\n"
137		"0:  la   %0,1f-0b(%0)\n"
138		"    st   %0,4(%1)\n"
139		"    oi   4(%1),0x80\n"
140		"    lpsw 0(%1)\n"
141		"1:  la   %0,2f-1b(%0)\n"
142		"    st   %0,4(%1)\n"
143		"    oi   4(%1),0x80\n"
144		"    ni   1(%1),0xf9\n"
145		"    lpsw 0(%1)\n"
146		"2:"
147		: "=&a" (reg) : "a" (&wait_psw) : "memory", "cc" );
148#else /* CONFIG_ARCH_S390X */
149	asm volatile (
150		"    larl  %0,0f\n"
151		"    stg   %0,8(%1)\n"
152		"    lpswe 0(%1)\n"
153		"0:  larl  %0,1f\n"
154		"    stg   %0,8(%1)\n"
155		"    ni    1(%1),0xf9\n"
156		"    lpswe 0(%1)\n"
157		"1:"
158		: "=&a" (reg) : "a" (&wait_psw) : "memory", "cc" );
159#endif /* CONFIG_ARCH_S390X */
160}
161
162void cpu_idle(void)
163{
164	for (;;)
165		default_idle();
166}
167
168void show_regs(struct pt_regs *regs)
169{
170	struct task_struct *tsk = current;
171
172        printk("CPU:    %d    %s\n", tsk->thread_info->cpu, print_tainted());
173        printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
174	       current->comm, current->pid, (void *) tsk,
175	       (void *) tsk->thread.ksp);
176
177	show_registers(regs);
178	/* Show stack backtrace if pt_regs is from kernel mode */
179	if (!(regs->psw.mask & PSW_MASK_PSTATE))
180		show_trace(0,(unsigned long *) regs->gprs[15]);
181}
182
183extern void kernel_thread_starter(void);
184
185__asm__(".align 4\n"
186	"kernel_thread_starter:\n"
187	"    la    2,0(10)\n"
188	"    basr  14,9\n"
189	"    la    2,0\n"
190	"    br    11\n");
191
192int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
193{
194	struct pt_regs regs;
195
196	memset(&regs, 0, sizeof(regs));
197	regs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | PSW_MASK_EXT;
198	regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
199	regs.gprs[9] = (unsigned long) fn;
200	regs.gprs[10] = (unsigned long) arg;
201	regs.gprs[11] = (unsigned long) do_exit;
202	regs.orig_gpr2 = -1;
203
204	/* Ok, create the new process.. */
205	return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
206		       0, &regs, 0, NULL, NULL);
207}
208
209/*
210 * Free current thread data structures etc..
211 */
212void exit_thread(void)
213{
214}
215
216void flush_thread(void)
217{
218	clear_used_math();
219	clear_tsk_thread_flag(current, TIF_USEDFPU);
220}
221
222void release_thread(struct task_struct *dead_task)
223{
224}
225
226int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
227	unsigned long unused,
228        struct task_struct * p, struct pt_regs * regs)
229{
230        struct fake_frame
231          {
232	    struct stack_frame sf;
233            struct pt_regs childregs;
234          } *frame;
235
236        frame = ((struct fake_frame *)
237		 (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
238        p->thread.ksp = (unsigned long) frame;
239	/* Store access registers to kernel stack of new process. */
240        frame->childregs = *regs;
241	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
242        frame->childregs.gprs[15] = new_stackp;
243        frame->sf.back_chain = 0;
244
245        /* new return point is ret_from_fork */
246        frame->sf.gprs[8] = (unsigned long) ret_from_fork;
247
248        /* fake return stack for resume(), don't go back to schedule */
249        frame->sf.gprs[9] = (unsigned long) frame;
250
251	/* Save access registers to new thread structure. */
252	save_access_regs(&p->thread.acrs[0]);
253
254#ifndef CONFIG_ARCH_S390X
255        /*
256	 * save fprs to current->thread.fp_regs to merge them with
257	 * the emulated registers and then copy the result to the child.
258	 */
259	save_fp_regs(&current->thread.fp_regs);
260	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
261	       sizeof(s390_fp_regs));
262        p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _SEGMENT_TABLE;
263	/* Set a new TLS ?  */
264	if (clone_flags & CLONE_SETTLS)
265		p->thread.acrs[0] = regs->gprs[6];
266#else /* CONFIG_ARCH_S390X */
267	/* Save the fpu registers to new thread structure. */
268	save_fp_regs(&p->thread.fp_regs);
269        p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _REGION_TABLE;
270	/* Set a new TLS ?  */
271	if (clone_flags & CLONE_SETTLS) {
272		if (test_thread_flag(TIF_31BIT)) {
273			p->thread.acrs[0] = (unsigned int) regs->gprs[6];
274		} else {
275			p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
276			p->thread.acrs[1] = (unsigned int) regs->gprs[6];
277		}
278	}
279#endif /* CONFIG_ARCH_S390X */
280	/* start new process with ar4 pointing to the correct address space */
281	p->thread.mm_segment = get_fs();
282        /* Don't copy debug registers */
283        memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
284
285        return 0;
286}
287
288asmlinkage long sys_fork(struct pt_regs regs)
289{
290	return do_fork(SIGCHLD, regs.gprs[15], &regs, 0, NULL, NULL);
291}
292
293asmlinkage long sys_clone(struct pt_regs regs)
294{
295        unsigned long clone_flags;
296        unsigned long newsp;
297	int __user *parent_tidptr, *child_tidptr;
298
299        clone_flags = regs.gprs[3];
300        newsp = regs.orig_gpr2;
301	parent_tidptr = (int __user *) regs.gprs[4];
302	child_tidptr = (int __user *) regs.gprs[5];
303        if (!newsp)
304                newsp = regs.gprs[15];
305        return do_fork(clone_flags, newsp, &regs, 0,
306		       parent_tidptr, child_tidptr);
307}
308
309/*
310 * This is trivial, and on the face of it looks like it
311 * could equally well be done in user mode.
312 *
313 * Not so, for quite unobvious reasons - register pressure.
314 * In user mode vfork() cannot have a stack frame, and if
315 * done by calling the "clone()" system call directly, you
316 * do not have enough call-clobbered registers to hold all
317 * the information you need.
318 */
319asmlinkage long sys_vfork(struct pt_regs regs)
320{
321	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
322		       regs.gprs[15], &regs, 0, NULL, NULL);
323}
324
325/*
326 * sys_execve() executes a new program.
327 */
328asmlinkage long sys_execve(struct pt_regs regs)
329{
330        int error;
331        char * filename;
332
333        filename = getname((char __user *) regs.orig_gpr2);
334        error = PTR_ERR(filename);
335        if (IS_ERR(filename))
336                goto out;
337        error = do_execve(filename, (char __user * __user *) regs.gprs[3],
338			  (char __user * __user *) regs.gprs[4], &regs);
339	if (error == 0) {
340		task_lock(current);
341		current->ptrace &= ~PT_DTRACE;
342		task_unlock(current);
343		current->thread.fp_regs.fpc = 0;
344		if (MACHINE_HAS_IEEE)
345			asm volatile("sfpc %0,%0" : : "d" (0));
346	}
347        putname(filename);
348out:
349        return error;
350}
351
352
353/*
354 * fill in the FPU structure for a core dump.
355 */
356int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
357{
358#ifndef CONFIG_ARCH_S390X
359        /*
360	 * save fprs to current->thread.fp_regs to merge them with
361	 * the emulated registers and then copy the result to the dump.
362	 */
363	save_fp_regs(&current->thread.fp_regs);
364	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
365#else /* CONFIG_ARCH_S390X */
366	save_fp_regs(fpregs);
367#endif /* CONFIG_ARCH_S390X */
368	return 1;
369}
370
371/*
372 * fill in the user structure for a core dump..
373 */
374void dump_thread(struct pt_regs * regs, struct user * dump)
375{
376
377/* changed the size calculations - should hopefully work better. lbt */
378	dump->magic = CMAGIC;
379	dump->start_code = 0;
380	dump->start_stack = regs->gprs[15] & ~(PAGE_SIZE - 1);
381	dump->u_tsize = current->mm->end_code >> PAGE_SHIFT;
382	dump->u_dsize = (current->mm->brk + PAGE_SIZE - 1) >> PAGE_SHIFT;
383	dump->u_dsize -= dump->u_tsize;
384	dump->u_ssize = 0;
385	if (dump->start_stack < TASK_SIZE)
386		dump->u_ssize = (TASK_SIZE - dump->start_stack) >> PAGE_SHIFT;
387	memcpy(&dump->regs, regs, sizeof(s390_regs));
388	dump_fpu (regs, &dump->regs.fp_regs);
389	dump->regs.per_info = current->thread.per_info;
390}
391
392unsigned long get_wchan(struct task_struct *p)
393{
394	struct stack_frame *sf, *low, *high;
395	unsigned long return_address;
396	int count;
397
398	if (!p || p == current || p->state == TASK_RUNNING || !p->thread_info)
399		return 0;
400	low = (struct stack_frame *) p->thread_info;
401	high = (struct stack_frame *)
402		((unsigned long) p->thread_info + THREAD_SIZE) - 1;
403	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
404	if (sf <= low || sf > high)
405		return 0;
406	for (count = 0; count < 16; count++) {
407		sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
408		if (sf <= low || sf > high)
409			return 0;
410		return_address = sf->gprs[8] & PSW_ADDR_INSN;
411		if (!in_sched_functions(return_address))
412			return return_address;
413	}
414	return 0;
415}
416