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 <asm/cpu_mf.h>
33 #include <asm/io.h>
34 #include <asm/processor.h>
35 #include <asm/vtimer.h>
36 #include <asm/exec.h>
37 #include <asm/irq.h>
38 #include <asm/nmi.h>
39 #include <asm/smp.h>
40 #include <asm/stacktrace.h>
41 #include <asm/switch_to.h>
42 #include <asm/runtime_instr.h>
43 #include "entry.h"
44
45 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
46
47 extern void kernel_thread_starter(void);
48
flush_thread(void)49 void flush_thread(void)
50 {
51 }
52
arch_setup_new_exec(void)53 void arch_setup_new_exec(void)
54 {
55 if (S390_lowcore.current_pid != current->pid) {
56 S390_lowcore.current_pid = current->pid;
57 if (test_facility(40))
58 lpp(&S390_lowcore.lpp);
59 }
60 }
61
arch_release_task_struct(struct task_struct * tsk)62 void arch_release_task_struct(struct task_struct *tsk)
63 {
64 runtime_instr_release(tsk);
65 guarded_storage_release(tsk);
66 }
67
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)68 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
69 {
70 /*
71 * Save the floating-point or vector register state of the current
72 * task and set the CIF_FPU flag to lazy restore the FPU register
73 * state when returning to user space.
74 */
75 save_fpu_regs();
76
77 memcpy(dst, src, arch_task_struct_size);
78 dst->thread.fpu.regs = dst->thread.fpu.fprs;
79
80 /*
81 * Don't transfer over the runtime instrumentation or the guarded
82 * storage control block pointers. These fields are cleared here instead
83 * of in copy_thread() to avoid premature freeing of associated memory
84 * on fork() failure. Wait to clear the RI flag because ->stack still
85 * refers to the source thread.
86 */
87 dst->thread.ri_cb = NULL;
88 dst->thread.gs_cb = NULL;
89 dst->thread.gs_bc_cb = NULL;
90
91 return 0;
92 }
93
copy_thread_tls(unsigned long clone_flags,unsigned long new_stackp,unsigned long arg,struct task_struct * p,unsigned long tls)94 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
95 unsigned long arg, struct task_struct *p, unsigned long tls)
96 {
97 struct fake_frame
98 {
99 struct stack_frame sf;
100 struct pt_regs childregs;
101 } *frame;
102
103 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
104 p->thread.ksp = (unsigned long) frame;
105 /* Save access registers to new thread structure. */
106 save_access_regs(&p->thread.acrs[0]);
107 /* start new process with ar4 pointing to the correct address space */
108 p->thread.mm_segment = get_fs();
109 /* Don't copy debug registers */
110 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
111 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
112 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
113 p->thread.per_flags = 0;
114 /* Initialize per thread user and system timer values */
115 p->thread.user_timer = 0;
116 p->thread.guest_timer = 0;
117 p->thread.system_timer = 0;
118 p->thread.hardirq_timer = 0;
119 p->thread.softirq_timer = 0;
120 p->thread.last_break = 1;
121
122 frame->sf.back_chain = 0;
123 /* new return point is ret_from_fork */
124 frame->sf.gprs[8] = (unsigned long) ret_from_fork;
125 /* fake return stack for resume(), don't go back to schedule */
126 frame->sf.gprs[9] = (unsigned long) frame;
127
128 /* Store access registers to kernel stack of new process. */
129 if (unlikely(p->flags & PF_KTHREAD)) {
130 /* kernel thread */
131 memset(&frame->childregs, 0, sizeof(struct pt_regs));
132 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
133 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
134 frame->childregs.psw.addr =
135 (unsigned long) kernel_thread_starter;
136 frame->childregs.gprs[9] = new_stackp; /* function */
137 frame->childregs.gprs[10] = arg;
138 frame->childregs.gprs[11] = (unsigned long) do_exit;
139 frame->childregs.orig_gpr2 = -1;
140
141 return 0;
142 }
143 frame->childregs = *current_pt_regs();
144 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
145 frame->childregs.flags = 0;
146 if (new_stackp)
147 frame->childregs.gprs[15] = new_stackp;
148 /*
149 * Clear the runtime instrumentation flag after the above childregs
150 * copy. The CB pointer was already cleared in arch_dup_task_struct().
151 */
152 frame->childregs.psw.mask &= ~PSW_MASK_RI;
153
154 /* Set a new TLS ? */
155 if (clone_flags & CLONE_SETTLS) {
156 if (is_compat_task()) {
157 p->thread.acrs[0] = (unsigned int)tls;
158 } else {
159 p->thread.acrs[0] = (unsigned int)(tls >> 32);
160 p->thread.acrs[1] = (unsigned int)tls;
161 }
162 }
163 return 0;
164 }
165
execve_tail(void)166 asmlinkage void execve_tail(void)
167 {
168 current->thread.fpu.fpc = 0;
169 asm volatile("sfpc %0" : : "d" (0));
170 }
171
172 /*
173 * fill in the FPU structure for a core dump.
174 */
dump_fpu(struct pt_regs * regs,s390_fp_regs * fpregs)175 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
176 {
177 save_fpu_regs();
178 fpregs->fpc = current->thread.fpu.fpc;
179 fpregs->pad = 0;
180 if (MACHINE_HAS_VX)
181 convert_vx_to_fp((freg_t *)&fpregs->fprs,
182 current->thread.fpu.vxrs);
183 else
184 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
185 sizeof(fpregs->fprs));
186 return 1;
187 }
188 EXPORT_SYMBOL(dump_fpu);
189
get_wchan(struct task_struct * p)190 unsigned long get_wchan(struct task_struct *p)
191 {
192 struct stack_frame *sf, *low, *high;
193 unsigned long return_address;
194 int count;
195
196 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
197 return 0;
198
199 if (!try_get_task_stack(p))
200 return 0;
201
202 low = task_stack_page(p);
203 high = (struct stack_frame *) task_pt_regs(p);
204 sf = (struct stack_frame *) p->thread.ksp;
205 if (sf <= low || sf > high) {
206 return_address = 0;
207 goto out;
208 }
209 for (count = 0; count < 16; count++) {
210 sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain);
211 if (sf <= low || sf > high) {
212 return_address = 0;
213 goto out;
214 }
215 return_address = READ_ONCE_NOCHECK(sf->gprs[8]);
216 if (!in_sched_functions(return_address))
217 goto out;
218 }
219 out:
220 put_task_stack(p);
221 return return_address;
222 }
223
arch_align_stack(unsigned long sp)224 unsigned long arch_align_stack(unsigned long sp)
225 {
226 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
227 sp -= get_random_int() & ~PAGE_MASK;
228 return sp & ~0xf;
229 }
230
brk_rnd(void)231 static inline unsigned long brk_rnd(void)
232 {
233 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
234 }
235
arch_randomize_brk(struct mm_struct * mm)236 unsigned long arch_randomize_brk(struct mm_struct *mm)
237 {
238 unsigned long ret;
239
240 ret = PAGE_ALIGN(mm->brk + brk_rnd());
241 return (ret > mm->brk) ? ret : mm->brk;
242 }
243
set_fs_fixup(void)244 void set_fs_fixup(void)
245 {
246 struct pt_regs *regs = current_pt_regs();
247 static bool warned;
248
249 set_fs(USER_DS);
250 if (warned)
251 return;
252 WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
253 show_registers(regs);
254 warned = true;
255 }
256