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/init_task.h>
31 #include <linux/entry-common.h>
32 #include <linux/io.h>
33 #include <asm/guarded_storage.h>
34 #include <asm/access-regs.h>
35 #include <asm/switch_to.h>
36 #include <asm/cpu_mf.h>
37 #include <asm/processor.h>
38 #include <asm/ptrace.h>
39 #include <asm/vtimer.h>
40 #include <asm/exec.h>
41 #include <asm/fpu.h>
42 #include <asm/irq.h>
43 #include <asm/nmi.h>
44 #include <asm/smp.h>
45 #include <asm/stacktrace.h>
46 #include <asm/runtime_instr.h>
47 #include <asm/unwind.h>
48 #include "entry.h"
49
50 void ret_from_fork(void) asm("ret_from_fork");
51
__ret_from_fork(struct task_struct * prev,struct pt_regs * regs)52 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
53 {
54 void (*func)(void *arg);
55
56 schedule_tail(prev);
57
58 if (!user_mode(regs)) {
59 /* Kernel thread */
60 func = (void *)regs->gprs[9];
61 func((void *)regs->gprs[10]);
62 }
63 clear_pt_regs_flag(regs, PIF_SYSCALL);
64 syscall_exit_to_user_mode(regs);
65 }
66
flush_thread(void)67 void flush_thread(void)
68 {
69 }
70
arch_setup_new_exec(void)71 void arch_setup_new_exec(void)
72 {
73 if (get_lowcore()->current_pid != current->pid) {
74 get_lowcore()->current_pid = current->pid;
75 if (test_facility(40))
76 lpp(&get_lowcore()->lpp);
77 }
78 }
79
arch_release_task_struct(struct task_struct * tsk)80 void arch_release_task_struct(struct task_struct *tsk)
81 {
82 runtime_instr_release(tsk);
83 guarded_storage_release(tsk);
84 }
85
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)86 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
87 {
88 save_user_fpu_regs();
89
90 *dst = *src;
91 dst->thread.kfpu_flags = 0;
92
93 /*
94 * Don't transfer over the runtime instrumentation or the guarded
95 * storage control block pointers. These fields are cleared here instead
96 * of in copy_thread() to avoid premature freeing of associated memory
97 * on fork() failure. Wait to clear the RI flag because ->stack still
98 * refers to the source thread.
99 */
100 dst->thread.ri_cb = NULL;
101 dst->thread.gs_cb = NULL;
102 dst->thread.gs_bc_cb = NULL;
103
104 return 0;
105 }
106
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)107 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
108 {
109 unsigned long clone_flags = args->flags;
110 unsigned long new_stackp = args->stack;
111 unsigned long tls = args->tls;
112 struct fake_frame
113 {
114 struct stack_frame sf;
115 struct pt_regs childregs;
116 } *frame;
117
118 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
119 p->thread.ksp = (unsigned long) frame;
120 /* Save access registers to new thread structure. */
121 save_access_regs(&p->thread.acrs[0]);
122 /* start new process with ar4 pointing to the correct address space */
123 /* Don't copy debug registers */
124 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
125 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
126 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
127 p->thread.per_flags = 0;
128 /* Initialize per thread user and system timer values */
129 p->thread.user_timer = 0;
130 p->thread.guest_timer = 0;
131 p->thread.system_timer = 0;
132 p->thread.hardirq_timer = 0;
133 p->thread.softirq_timer = 0;
134 p->thread.last_break = 1;
135
136 frame->sf.back_chain = 0;
137 frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs;
138 frame->sf.gprs[12 - 6] = (unsigned long)p;
139 /* new return point is ret_from_fork */
140 frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;
141 /* fake return stack for resume(), don't go back to schedule */
142 frame->sf.gprs[15 - 6] = (unsigned long)frame;
143
144 /* Store access registers to kernel stack of new process. */
145 if (unlikely(args->fn)) {
146 /* kernel thread */
147 memset(&frame->childregs, 0, sizeof(struct pt_regs));
148 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO |
149 PSW_MASK_EXT | PSW_MASK_MCHECK;
150 frame->childregs.gprs[9] = (unsigned long)args->fn;
151 frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
152 frame->childregs.orig_gpr2 = -1;
153 frame->childregs.last_break = 1;
154 return 0;
155 }
156 frame->childregs = *current_pt_regs();
157 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
158 frame->childregs.flags = 0;
159 if (new_stackp)
160 frame->childregs.gprs[15] = new_stackp;
161 /*
162 * Clear the runtime instrumentation flag after the above childregs
163 * copy. The CB pointer was already cleared in arch_dup_task_struct().
164 */
165 frame->childregs.psw.mask &= ~PSW_MASK_RI;
166
167 /* Set a new TLS ? */
168 if (clone_flags & CLONE_SETTLS) {
169 if (is_compat_task()) {
170 p->thread.acrs[0] = (unsigned int)tls;
171 } else {
172 p->thread.acrs[0] = (unsigned int)(tls >> 32);
173 p->thread.acrs[1] = (unsigned int)tls;
174 }
175 }
176 /*
177 * s390 stores the svc return address in arch_data when calling
178 * sigreturn()/restart_syscall() via vdso. 1 means no valid address
179 * stored.
180 */
181 p->restart_block.arch_data = 1;
182 return 0;
183 }
184
execve_tail(void)185 void execve_tail(void)
186 {
187 current->thread.ufpu.fpc = 0;
188 fpu_sfpc(0);
189 }
190
__switch_to(struct task_struct * prev,struct task_struct * next)191 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
192 {
193 save_user_fpu_regs();
194 save_kernel_fpu_regs(&prev->thread);
195 save_access_regs(&prev->thread.acrs[0]);
196 save_ri_cb(prev->thread.ri_cb);
197 save_gs_cb(prev->thread.gs_cb);
198 update_cr_regs(next);
199 restore_kernel_fpu_regs(&next->thread);
200 restore_access_regs(&next->thread.acrs[0]);
201 restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);
202 restore_gs_cb(next->thread.gs_cb);
203 return __switch_to_asm(prev, next);
204 }
205
__get_wchan(struct task_struct * p)206 unsigned long __get_wchan(struct task_struct *p)
207 {
208 struct unwind_state state;
209 unsigned long ip = 0;
210
211 if (!task_stack_page(p))
212 return 0;
213
214 if (!try_get_task_stack(p))
215 return 0;
216
217 unwind_for_each_frame(&state, p, NULL, 0) {
218 if (state.stack_info.type != STACK_TYPE_TASK) {
219 ip = 0;
220 break;
221 }
222
223 ip = unwind_get_return_address(&state);
224 if (!ip)
225 break;
226
227 if (!in_sched_functions(ip))
228 break;
229 }
230
231 put_task_stack(p);
232 return ip;
233 }
234
arch_align_stack(unsigned long sp)235 unsigned long arch_align_stack(unsigned long sp)
236 {
237 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
238 sp -= get_random_u32_below(PAGE_SIZE);
239 return sp & ~0xf;
240 }
241
brk_rnd(void)242 static inline unsigned long brk_rnd(void)
243 {
244 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
245 }
246
arch_randomize_brk(struct mm_struct * mm)247 unsigned long arch_randomize_brk(struct mm_struct *mm)
248 {
249 unsigned long ret;
250
251 ret = PAGE_ALIGN(mm->brk + brk_rnd());
252 return (ret > mm->brk) ? ret : mm->brk;
253 }
254