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 return 0;
80 }
81
copy_thread_tls(unsigned long clone_flags,unsigned long new_stackp,unsigned long arg,struct task_struct * p,unsigned long tls)82 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
83 unsigned long arg, struct task_struct *p, unsigned long tls)
84 {
85 struct fake_frame
86 {
87 struct stack_frame sf;
88 struct pt_regs childregs;
89 } *frame;
90
91 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
92 p->thread.ksp = (unsigned long) frame;
93 /* Save access registers to new thread structure. */
94 save_access_regs(&p->thread.acrs[0]);
95 /* start new process with ar4 pointing to the correct address space */
96 p->thread.mm_segment = get_fs();
97 /* Don't copy debug registers */
98 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
99 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
100 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
101 p->thread.per_flags = 0;
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
execve_tail(void)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 */
dump_fpu(struct pt_regs * regs,s390_fp_regs * fpregs)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
get_wchan(struct task_struct * p)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
188 if (!try_get_task_stack(p))
189 return 0;
190
191 low = task_stack_page(p);
192 high = (struct stack_frame *) task_pt_regs(p);
193 sf = (struct stack_frame *) p->thread.ksp;
194 if (sf <= low || sf > high) {
195 return_address = 0;
196 goto out;
197 }
198 for (count = 0; count < 16; count++) {
199 sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain);
200 if (sf <= low || sf > high) {
201 return_address = 0;
202 goto out;
203 }
204 return_address = READ_ONCE_NOCHECK(sf->gprs[8]);
205 if (!in_sched_functions(return_address))
206 goto out;
207 }
208 out:
209 put_task_stack(p);
210 return return_address;
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
set_fs_fixup(void)233 void set_fs_fixup(void)
234 {
235 struct pt_regs *regs = current_pt_regs();
236 static bool warned;
237
238 set_fs(USER_DS);
239 if (warned)
240 return;
241 WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
242 show_registers(regs);
243 warned = true;
244 }
245