xref: /openbmc/linux/arch/s390/kernel/process.c (revision 4da722ca)
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/elf-randomize.h>
11 #include <linux/compiler.h>
12 #include <linux/cpu.h>
13 #include <linux/sched.h>
14 #include <linux/sched/debug.h>
15 #include <linux/sched/task.h>
16 #include <linux/sched/task_stack.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.h>
19 #include <linux/elfcore.h>
20 #include <linux/smp.h>
21 #include <linux/slab.h>
22 #include <linux/interrupt.h>
23 #include <linux/tick.h>
24 #include <linux/personality.h>
25 #include <linux/syscalls.h>
26 #include <linux/compat.h>
27 #include <linux/kprobes.h>
28 #include <linux/random.h>
29 #include <linux/export.h>
30 #include <linux/init_task.h>
31 #include <asm/io.h>
32 #include <asm/processor.h>
33 #include <asm/vtimer.h>
34 #include <asm/exec.h>
35 #include <asm/irq.h>
36 #include <asm/nmi.h>
37 #include <asm/smp.h>
38 #include <asm/switch_to.h>
39 #include <asm/runtime_instr.h>
40 #include "entry.h"
41 
42 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
43 
44 extern void kernel_thread_starter(void);
45 
46 /*
47  * Free current thread data structures etc..
48  */
49 void exit_thread(struct task_struct *tsk)
50 {
51 	if (tsk == current) {
52 		exit_thread_runtime_instr();
53 		exit_thread_gs();
54 	}
55 }
56 
57 void flush_thread(void)
58 {
59 }
60 
61 void release_thread(struct task_struct *dead_task)
62 {
63 }
64 
65 void arch_release_task_struct(struct task_struct *tsk)
66 {
67 }
68 
69 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
70 {
71 	/*
72 	 * Save the floating-point or vector register state of the current
73 	 * task and set the CIF_FPU flag to lazy restore the FPU register
74 	 * state when returning to user space.
75 	 */
76 	save_fpu_regs();
77 
78 	memcpy(dst, src, arch_task_struct_size);
79 	dst->thread.fpu.regs = dst->thread.fpu.fprs;
80 	return 0;
81 }
82 
83 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
84 		    unsigned long arg, struct task_struct *p, unsigned long tls)
85 {
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 	p->thread.user_timer = 0;
104 	p->thread.guest_timer = 0;
105 	p->thread.system_timer = 0;
106 	p->thread.hardirq_timer = 0;
107 	p->thread.softirq_timer = 0;
108 
109 	frame->sf.back_chain = 0;
110 	/* new return point is ret_from_fork */
111 	frame->sf.gprs[8] = (unsigned long) ret_from_fork;
112 	/* fake return stack for resume(), don't go back to schedule */
113 	frame->sf.gprs[9] = (unsigned long) frame;
114 
115 	/* Store access registers to kernel stack of new process. */
116 	if (unlikely(p->flags & PF_KTHREAD)) {
117 		/* kernel thread */
118 		memset(&frame->childregs, 0, sizeof(struct pt_regs));
119 		frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
120 				PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
121 		frame->childregs.psw.addr =
122 				(unsigned long) kernel_thread_starter;
123 		frame->childregs.gprs[9] = new_stackp; /* function */
124 		frame->childregs.gprs[10] = arg;
125 		frame->childregs.gprs[11] = (unsigned long) do_exit;
126 		frame->childregs.orig_gpr2 = -1;
127 
128 		return 0;
129 	}
130 	frame->childregs = *current_pt_regs();
131 	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
132 	frame->childregs.flags = 0;
133 	if (new_stackp)
134 		frame->childregs.gprs[15] = new_stackp;
135 
136 	/* Don't copy runtime instrumentation info */
137 	p->thread.ri_cb = NULL;
138 	frame->childregs.psw.mask &= ~PSW_MASK_RI;
139 	/* Don't copy guarded storage control block */
140 	p->thread.gs_cb = NULL;
141 	p->thread.gs_bc_cb = NULL;
142 
143 	/* Set a new TLS ?  */
144 	if (clone_flags & CLONE_SETTLS) {
145 		if (is_compat_task()) {
146 			p->thread.acrs[0] = (unsigned int)tls;
147 		} else {
148 			p->thread.acrs[0] = (unsigned int)(tls >> 32);
149 			p->thread.acrs[1] = (unsigned int)tls;
150 		}
151 	}
152 	return 0;
153 }
154 
155 asmlinkage void execve_tail(void)
156 {
157 	current->thread.fpu.fpc = 0;
158 	asm volatile("sfpc %0" : : "d" (0));
159 }
160 
161 /*
162  * fill in the FPU structure for a core dump.
163  */
164 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
165 {
166 	save_fpu_regs();
167 	fpregs->fpc = current->thread.fpu.fpc;
168 	fpregs->pad = 0;
169 	if (MACHINE_HAS_VX)
170 		convert_vx_to_fp((freg_t *)&fpregs->fprs,
171 				 current->thread.fpu.vxrs);
172 	else
173 		memcpy(&fpregs->fprs, current->thread.fpu.fprs,
174 		       sizeof(fpregs->fprs));
175 	return 1;
176 }
177 EXPORT_SYMBOL(dump_fpu);
178 
179 unsigned long get_wchan(struct task_struct *p)
180 {
181 	struct stack_frame *sf, *low, *high;
182 	unsigned long return_address;
183 	int count;
184 
185 	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
186 		return 0;
187 	low = task_stack_page(p);
188 	high = (struct stack_frame *) task_pt_regs(p);
189 	sf = (struct stack_frame *) p->thread.ksp;
190 	if (sf <= low || sf > high)
191 		return 0;
192 	for (count = 0; count < 16; count++) {
193 		sf = (struct stack_frame *) sf->back_chain;
194 		if (sf <= low || sf > high)
195 			return 0;
196 		return_address = sf->gprs[8];
197 		if (!in_sched_functions(return_address))
198 			return return_address;
199 	}
200 	return 0;
201 }
202 
203 unsigned long arch_align_stack(unsigned long sp)
204 {
205 	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
206 		sp -= get_random_int() & ~PAGE_MASK;
207 	return sp & ~0xf;
208 }
209 
210 static inline unsigned long brk_rnd(void)
211 {
212 	return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
213 }
214 
215 unsigned long arch_randomize_brk(struct mm_struct *mm)
216 {
217 	unsigned long ret;
218 
219 	ret = PAGE_ALIGN(mm->brk + brk_rnd());
220 	return (ret > mm->brk) ? ret : mm->brk;
221 }
222 
223 void set_fs_fixup(void)
224 {
225 	struct pt_regs *regs = current_pt_regs();
226 	static bool warned;
227 
228 	set_fs(USER_DS);
229 	if (warned)
230 		return;
231 	WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
232 	show_registers(regs);
233 	warned = true;
234 }
235