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/compat.h>
28 #include <linux/kprobes.h>
29 #include <linux/random.h>
30 #include <linux/export.h>
31 #include <linux/init_task.h>
32 #include <linux/entry-common.h>
33 #include <asm/cpu_mf.h>
34 #include <asm/io.h>
35 #include <asm/processor.h>
36 #include <asm/vtimer.h>
37 #include <asm/exec.h>
38 #include <asm/irq.h>
39 #include <asm/nmi.h>
40 #include <asm/smp.h>
41 #include <asm/stacktrace.h>
42 #include <asm/switch_to.h>
43 #include <asm/runtime_instr.h>
44 #include <asm/unwind.h>
45 #include "entry.h"
46
47 void ret_from_fork(void) asm("ret_from_fork");
48
__ret_from_fork(struct task_struct * prev,struct pt_regs * regs)49 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
50 {
51 void (*func)(void *arg);
52
53 schedule_tail(prev);
54
55 if (!user_mode(regs)) {
56 /* Kernel thread */
57 func = (void *)regs->gprs[9];
58 func((void *)regs->gprs[10]);
59 }
60 clear_pt_regs_flag(regs, PIF_SYSCALL);
61 syscall_exit_to_user_mode(regs);
62 }
63
flush_thread(void)64 void flush_thread(void)
65 {
66 }
67
arch_setup_new_exec(void)68 void arch_setup_new_exec(void)
69 {
70 if (S390_lowcore.current_pid != current->pid) {
71 S390_lowcore.current_pid = current->pid;
72 if (test_facility(40))
73 lpp(&S390_lowcore.lpp);
74 }
75 }
76
arch_release_task_struct(struct task_struct * tsk)77 void arch_release_task_struct(struct task_struct *tsk)
78 {
79 runtime_instr_release(tsk);
80 guarded_storage_release(tsk);
81 }
82
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)83 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
84 {
85 /*
86 * Save the floating-point or vector register state of the current
87 * task and set the CIF_FPU flag to lazy restore the FPU register
88 * state when returning to user space.
89 */
90 save_fpu_regs();
91
92 memcpy(dst, src, arch_task_struct_size);
93 dst->thread.fpu.regs = dst->thread.fpu.fprs;
94 return 0;
95 }
96
copy_thread(unsigned long clone_flags,unsigned long new_stackp,unsigned long arg,struct task_struct * p,unsigned long tls)97 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
98 unsigned long arg, struct task_struct *p, unsigned long tls)
99 {
100 struct fake_frame
101 {
102 struct stack_frame sf;
103 struct pt_regs childregs;
104 } *frame;
105
106 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
107 p->thread.ksp = (unsigned long) frame;
108 /* Save access registers to new thread structure. */
109 save_access_regs(&p->thread.acrs[0]);
110 /* start new process with ar4 pointing to the correct address space */
111 /* Don't copy debug registers */
112 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
113 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
114 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
115 p->thread.per_flags = 0;
116 /* Initialize per thread user and system timer values */
117 p->thread.user_timer = 0;
118 p->thread.guest_timer = 0;
119 p->thread.system_timer = 0;
120 p->thread.hardirq_timer = 0;
121 p->thread.softirq_timer = 0;
122 p->thread.last_break = 1;
123
124 frame->sf.back_chain = 0;
125 frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame);
126 frame->sf.gprs[6] = (unsigned long)p;
127 /* new return point is ret_from_fork */
128 frame->sf.gprs[8] = (unsigned long)ret_from_fork;
129 /* fake return stack for resume(), don't go back to schedule */
130 frame->sf.gprs[9] = (unsigned long)frame;
131
132 /* Store access registers to kernel stack of new process. */
133 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
134 /* kernel thread */
135 memset(&frame->childregs, 0, sizeof(struct pt_regs));
136 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
137 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
138 frame->childregs.psw.addr =
139 (unsigned long)__ret_from_fork;
140 frame->childregs.gprs[9] = new_stackp; /* function */
141 frame->childregs.gprs[10] = arg;
142 frame->childregs.gprs[11] = (unsigned long)do_exit;
143 frame->childregs.orig_gpr2 = -1;
144
145 return 0;
146 }
147 frame->childregs = *current_pt_regs();
148 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
149 frame->childregs.flags = 0;
150 if (new_stackp)
151 frame->childregs.gprs[15] = new_stackp;
152
153 /* Don't copy runtime instrumentation info */
154 p->thread.ri_cb = NULL;
155 frame->childregs.psw.mask &= ~PSW_MASK_RI;
156 /* Don't copy guarded storage control block */
157 p->thread.gs_cb = NULL;
158 p->thread.gs_bc_cb = NULL;
159
160 /* Set a new TLS ? */
161 if (clone_flags & CLONE_SETTLS) {
162 if (is_compat_task()) {
163 p->thread.acrs[0] = (unsigned int)tls;
164 } else {
165 p->thread.acrs[0] = (unsigned int)(tls >> 32);
166 p->thread.acrs[1] = (unsigned int)tls;
167 }
168 }
169 /*
170 * s390 stores the svc return address in arch_data when calling
171 * sigreturn()/restart_syscall() via vdso. 1 means no valid address
172 * stored.
173 */
174 p->restart_block.arch_data = 1;
175 return 0;
176 }
177
execve_tail(void)178 void execve_tail(void)
179 {
180 current->thread.fpu.fpc = 0;
181 asm volatile("sfpc %0" : : "d" (0));
182 }
183
get_wchan(struct task_struct * p)184 unsigned long get_wchan(struct task_struct *p)
185 {
186 struct unwind_state state;
187 unsigned long ip = 0;
188
189 if (!p || p == current || task_is_running(p) || !task_stack_page(p))
190 return 0;
191
192 if (!try_get_task_stack(p))
193 return 0;
194
195 unwind_for_each_frame(&state, p, NULL, 0) {
196 if (state.stack_info.type != STACK_TYPE_TASK) {
197 ip = 0;
198 break;
199 }
200
201 ip = unwind_get_return_address(&state);
202 if (!ip)
203 break;
204
205 if (!in_sched_functions(ip))
206 break;
207 }
208
209 put_task_stack(p);
210 return ip;
211 }
212
arch_align_stack(unsigned long sp)213 unsigned long arch_align_stack(unsigned long sp)
214 {
215 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
216 sp -= get_random_int() & ~PAGE_MASK;
217 return sp & ~0xf;
218 }
219
brk_rnd(void)220 static inline unsigned long brk_rnd(void)
221 {
222 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
223 }
224
arch_randomize_brk(struct mm_struct * mm)225 unsigned long arch_randomize_brk(struct mm_struct *mm)
226 {
227 unsigned long ret;
228
229 ret = PAGE_ALIGN(mm->brk + brk_rnd());
230 return (ret > mm->brk) ? ret : mm->brk;
231 }
232
