1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file handles the architecture dependent parts of process handling.
4 *
5 * Copyright IBM Corp. 1999, 2009
6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 * Hartmut Penner <hp@de.ibm.com>,
8 * Denis Joseph Barrow,
9 */
10
11#include <linux/elf-randomize.h>
12#include <linux/compiler.h>
13#include <linux/cpu.h>
14#include <linux/sched.h>
15#include <linux/sched/debug.h>
16#include <linux/sched/task.h>
17#include <linux/sched/task_stack.h>
18#include <linux/kernel.h>
19#include <linux/mm.h>
20#include <linux/elfcore.h>
21#include <linux/smp.h>
22#include <linux/slab.h>
23#include <linux/interrupt.h>
24#include <linux/tick.h>
25#include <linux/personality.h>
26#include <linux/syscalls.h>
27#include <linux/kprobes.h>
28#include <linux/random.h>
29#include <linux/init_task.h>
30#include <linux/entry-common.h>
31#include <linux/io.h>
32#include <asm/guarded_storage.h>
33#include <asm/access-regs.h>
34#include <asm/switch_to.h>
35#include <asm/cpu_mf.h>
36#include <asm/processor.h>
37#include <asm/ptrace.h>
38#include <asm/vtimer.h>
39#include <asm/exec.h>
40#include <asm/fpu.h>
41#include <asm/irq.h>
42#include <asm/nmi.h>
43#include <asm/smp.h>
44#include <asm/stacktrace.h>
45#include <asm/runtime_instr.h>
46#include <asm/unwind.h>
47#include "entry.h"
48
49void ret_from_fork(void) asm("ret_from_fork");
50
51void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
52{
53 void (*func)(void *arg);
54
55 schedule_tail(prev);
56
57 if (!user_mode(regs)) {
58 /* Kernel thread */
59 func = (void *)regs->gprs[9];
60 func((void *)regs->gprs[10]);
61 }
62 clear_pt_regs_flag(regs, PIF_SYSCALL);
63 syscall_exit_to_user_mode(regs);
64}
65
66void flush_thread(void)
67{
68}
69
70void arch_setup_new_exec(void)
71{
72 if (get_lowcore()->current_pid != current->pid) {
73 get_lowcore()->current_pid = current->pid;
74 if (test_facility(40))
75 lpp(&get_lowcore()->lpp);
76 }
77}
78
79void arch_release_task_struct(struct task_struct *tsk)
80{
81 runtime_instr_release(tsk);
82 guarded_storage_release(tsk);
83}
84
85int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
86{
87 save_user_fpu_regs();
88
89 *dst = *src;
90 dst->thread.kfpu_flags = 0;
91
92 /*
93 * Don't transfer over the runtime instrumentation or the guarded
94 * storage control block pointers. These fields are cleared here instead
95 * of in copy_thread() to avoid premature freeing of associated memory
96 * on fork() failure. Wait to clear the RI flag because ->stack still
97 * refers to the source thread.
98 */
99 dst->thread.ri_cb = NULL;
100 dst->thread.gs_cb = NULL;
101 dst->thread.gs_bc_cb = NULL;
102
103 return 0;
104}
105
106int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
107{
108 u64 clone_flags = args->flags;
109 unsigned long new_stackp = args->stack;
110 unsigned long tls = args->tls;
111 struct fake_frame
112 {
113 struct stack_frame sf;
114 struct pt_regs childregs;
115 } *frame;
116
117 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
118 p->thread.ksp = (unsigned long) frame;
119 /* Save access registers to new thread structure. */
120 save_access_regs(&p->thread.acrs[0]);
121 /* start new process with ar4 pointing to the correct address space */
122 /* Don't copy debug registers */
123 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
124 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
125 clear_tsk_thread_flag(tsk: p, flag: TIF_SINGLE_STEP);
126 p->thread.per_flags = 0;
127 /* Initialize per thread user and system timer values */
128 p->thread.user_timer = 0;
129 p->thread.guest_timer = 0;
130 p->thread.system_timer = 0;
131 p->thread.hardirq_timer = 0;
132 p->thread.softirq_timer = 0;
133 p->thread.last_break = 1;
134
135 frame->sf.back_chain = 0;
136 frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs;
137 frame->sf.gprs[12 - 6] = (unsigned long)p;
138 /* new return point is ret_from_fork */
139 frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;
140 /* fake return stack for resume(), don't go back to schedule */
141 frame->sf.gprs[15 - 6] = (unsigned long)frame;
142
143 /* Store access registers to kernel stack of new process. */
144 if (unlikely(args->fn)) {
145 /* kernel thread */
146 memset(&frame->childregs, 0, sizeof(struct pt_regs));
147 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO |
148 PSW_MASK_EXT | PSW_MASK_MCHECK;
149 frame->childregs.gprs[9] = (unsigned long)args->fn;
150 frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
151 frame->childregs.orig_gpr2 = -1;
152 frame->childregs.last_break = 1;
153 return 0;
154 }
155 frame->childregs = *current_pt_regs();
156 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
157 frame->childregs.flags = 0;
158 if (new_stackp)
159 frame->childregs.gprs[15] = new_stackp;
160 /*
161 * Clear the runtime instrumentation flag after the above childregs
162 * copy. The CB pointer was already cleared in arch_dup_task_struct().
163 */
164 frame->childregs.psw.mask &= ~PSW_MASK_RI;
165
166 /* Set a new TLS ? */
167 if (clone_flags & CLONE_SETTLS) {
168 p->thread.acrs[0] = (unsigned int)(tls >> 32);
169 p->thread.acrs[1] = (unsigned int)tls;
170 }
171 /*
172 * s390 stores the svc return address in arch_data when calling
173 * sigreturn()/restart_syscall() via vdso. 1 means no valid address
174 * stored.
175 */
176 p->restart_block.arch_data = 1;
177 return 0;
178}
179
180void execve_tail(void)
181{
182 current->thread.ufpu.fpc = 0;
183 fpu_sfpc(0);
184}
185
186struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
187{
188 save_user_fpu_regs();
189 save_kernel_fpu_regs(&prev->thread);
190 save_access_regs(&prev->thread.acrs[0]);
191 save_ri_cb(prev->thread.ri_cb);
192 save_gs_cb(prev->thread.gs_cb);
193 update_cr_regs(next);
194 restore_kernel_fpu_regs(&next->thread);
195 restore_access_regs(&next->thread.acrs[0]);
196 restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);
197 restore_gs_cb(next->thread.gs_cb);
198 return __switch_to_asm(prev, next);
199}
200
201unsigned long __get_wchan(struct task_struct *p)
202{
203 struct unwind_state state;
204 unsigned long ip = 0;
205
206 if (!task_stack_page(task: p))
207 return 0;
208
209 if (!try_get_task_stack(tsk: p))
210 return 0;
211
212 unwind_for_each_frame(&state, p, NULL, 0) {
213 if (state.stack_info.type != STACK_TYPE_TASK) {
214 ip = 0;
215 break;
216 }
217
218 ip = unwind_get_return_address(state: &state);
219 if (!ip)
220 break;
221
222 if (!in_sched_functions(ip))
223 break;
224 }
225
226 put_task_stack(tsk: p);
227 return ip;
228}
229
230unsigned long arch_align_stack(unsigned long sp)
231{
232 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
233 sp -= get_random_u32_below(PAGE_SIZE);
234 return sp & ~0xf;
235}
236
237static inline unsigned long brk_rnd(void)
238{
239 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
240}
241
242unsigned long arch_randomize_brk(struct mm_struct *mm)
243{
244 unsigned long ret;
245
246 ret = PAGE_ALIGN(mm->brk + brk_rnd());
247 return (ret > mm->brk) ? ret : mm->brk;
248}
249

source code of linux/arch/s390/kernel/process.c