1/*
2 * This file handles the architecture dependent parts of process handling.
3 *
4 *    Copyright IBM Corp. 1999, 2009
5 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
6 *		 Hartmut Penner <hp@de.ibm.com>,
7 *		 Denis Joseph Barrow,
8 */
9
10#include <linux/compiler.h>
11#include <linux/cpu.h>
12#include <linux/sched.h>
13#include <linux/kernel.h>
14#include <linux/mm.h>
15#include <linux/elfcore.h>
16#include <linux/smp.h>
17#include <linux/slab.h>
18#include <linux/interrupt.h>
19#include <linux/tick.h>
20#include <linux/personality.h>
21#include <linux/syscalls.h>
22#include <linux/compat.h>
23#include <linux/kprobes.h>
24#include <linux/random.h>
25#include <linux/module.h>
26#include <asm/io.h>
27#include <asm/processor.h>
28#include <asm/vtimer.h>
29#include <asm/exec.h>
30#include <asm/irq.h>
31#include <asm/nmi.h>
32#include <asm/smp.h>
33#include <asm/switch_to.h>
34#include <asm/runtime_instr.h>
35#include "entry.h"
36
37asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
38
39/*
40 * Return saved PC of a blocked thread. used in kernel/sched.
41 * resume in entry.S does not create a new stack frame, it
42 * just stores the registers %r6-%r15 to the frame given by
43 * schedule. We want to return the address of the caller of
44 * schedule, so we have to walk the backchain one time to
45 * find the frame schedule() store its return address.
46 */
47unsigned long thread_saved_pc(struct task_struct *tsk)
48{
49	struct stack_frame *sf, *low, *high;
50
51	if (!tsk || !task_stack_page(tsk))
52		return 0;
53	low = task_stack_page(tsk);
54	high = (struct stack_frame *) task_pt_regs(tsk);
55	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
56	if (sf <= low || sf > high)
57		return 0;
58	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
59	if (sf <= low || sf > high)
60		return 0;
61	return sf->gprs[8];
62}
63
64extern void __kprobes kernel_thread_starter(void);
65
66/*
67 * Free current thread data structures etc..
68 */
69void exit_thread(void)
70{
71	exit_thread_runtime_instr();
72}
73
74void flush_thread(void)
75{
76}
77
78void release_thread(struct task_struct *dead_task)
79{
80}
81
82int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
83		unsigned long arg, struct task_struct *p)
84{
85	struct thread_info *ti;
86	struct fake_frame
87	{
88		struct stack_frame sf;
89		struct pt_regs childregs;
90	} *frame;
91
92	frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
93	p->thread.ksp = (unsigned long) frame;
94	/* Save access registers to new thread structure. */
95	save_access_regs(&p->thread.acrs[0]);
96	/* start new process with ar4 pointing to the correct address space */
97	p->thread.mm_segment = get_fs();
98	/* Don't copy debug registers */
99	memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
100	memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
101	clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
102	/* Initialize per thread user and system timer values */
103	ti = task_thread_info(p);
104	ti->user_timer = 0;
105	ti->system_timer = 0;
106
107	frame->sf.back_chain = 0;
108	/* new return point is ret_from_fork */
109	frame->sf.gprs[8] = (unsigned long) ret_from_fork;
110	/* fake return stack for resume(), don't go back to schedule */
111	frame->sf.gprs[9] = (unsigned long) frame;
112
113	/* Store access registers to kernel stack of new process. */
114	if (unlikely(p->flags & PF_KTHREAD)) {
115		/* kernel thread */
116		memset(&frame->childregs, 0, sizeof(struct pt_regs));
117		frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
118				PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
119		frame->childregs.psw.addr = PSW_ADDR_AMODE |
120				(unsigned long) kernel_thread_starter;
121		frame->childregs.gprs[9] = new_stackp; /* function */
122		frame->childregs.gprs[10] = arg;
123		frame->childregs.gprs[11] = (unsigned long) do_exit;
124		frame->childregs.orig_gpr2 = -1;
125
126		return 0;
127	}
128	frame->childregs = *current_pt_regs();
129	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
130	frame->childregs.flags = 0;
131	if (new_stackp)
132		frame->childregs.gprs[15] = new_stackp;
133
134	/* Don't copy runtime instrumentation info */
135	p->thread.ri_cb = NULL;
136	p->thread.ri_signum = 0;
137	frame->childregs.psw.mask &= ~PSW_MASK_RI;
138
139#ifndef CONFIG_64BIT
140	/*
141	 * save fprs to current->thread.fp_regs to merge them with
142	 * the emulated registers and then copy the result to the child.
143	 */
144	save_fp_ctl(&current->thread.fp_regs.fpc);
145	save_fp_regs(current->thread.fp_regs.fprs);
146	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
147	       sizeof(s390_fp_regs));
148	/* Set a new TLS ?  */
149	if (clone_flags & CLONE_SETTLS)
150		p->thread.acrs[0] = frame->childregs.gprs[6];
151#else /* CONFIG_64BIT */
152	/* Save the fpu registers to new thread structure. */
153	save_fp_ctl(&p->thread.fp_regs.fpc);
154	save_fp_regs(p->thread.fp_regs.fprs);
155	p->thread.fp_regs.pad = 0;
156	/* Set a new TLS ?  */
157	if (clone_flags & CLONE_SETTLS) {
158		unsigned long tls = frame->childregs.gprs[6];
159		if (is_compat_task()) {
160			p->thread.acrs[0] = (unsigned int)tls;
161		} else {
162			p->thread.acrs[0] = (unsigned int)(tls >> 32);
163			p->thread.acrs[1] = (unsigned int)tls;
164		}
165	}
166#endif /* CONFIG_64BIT */
167	return 0;
168}
169
170asmlinkage void execve_tail(void)
171{
172	current->thread.fp_regs.fpc = 0;
173	if (MACHINE_HAS_IEEE)
174		asm volatile("sfpc %0,%0" : : "d" (0));
175}
176
177/*
178 * fill in the FPU structure for a core dump.
179 */
180int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
181{
182#ifndef CONFIG_64BIT
183	/*
184	 * save fprs to current->thread.fp_regs to merge them with
185	 * the emulated registers and then copy the result to the dump.
186	 */
187	save_fp_ctl(&current->thread.fp_regs.fpc);
188	save_fp_regs(current->thread.fp_regs.fprs);
189	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
190#else /* CONFIG_64BIT */
191	save_fp_ctl(&fpregs->fpc);
192	save_fp_regs(fpregs->fprs);
193#endif /* CONFIG_64BIT */
194	return 1;
195}
196EXPORT_SYMBOL(dump_fpu);
197
198unsigned long get_wchan(struct task_struct *p)
199{
200	struct stack_frame *sf, *low, *high;
201	unsigned long return_address;
202	int count;
203
204	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
205		return 0;
206	low = task_stack_page(p);
207	high = (struct stack_frame *) task_pt_regs(p);
208	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
209	if (sf <= low || sf > high)
210		return 0;
211	for (count = 0; count < 16; count++) {
212		sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
213		if (sf <= low || sf > high)
214			return 0;
215		return_address = sf->gprs[8] & PSW_ADDR_INSN;
216		if (!in_sched_functions(return_address))
217			return return_address;
218	}
219	return 0;
220}
221
222unsigned long arch_align_stack(unsigned long sp)
223{
224	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
225		sp -= get_random_int() & ~PAGE_MASK;
226	return sp & ~0xf;
227}
228
229static inline unsigned long brk_rnd(void)
230{
231	/* 8MB for 32bit, 1GB for 64bit */
232	if (is_32bit_task())
233		return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
234	else
235		return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
236}
237
238unsigned long arch_randomize_brk(struct mm_struct *mm)
239{
240	unsigned long ret;
241
242	ret = PAGE_ALIGN(mm->brk + brk_rnd());
243	return (ret > mm->brk) ? ret : mm->brk;
244}
245
246unsigned long randomize_et_dyn(unsigned long base)
247{
248	unsigned long ret;
249
250	if (!(current->flags & PF_RANDOMIZE))
251		return base;
252	ret = PAGE_ALIGN(base + brk_rnd());
253	return (ret > base) ? ret : base;
254}
255