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 <linux/io.h> |
34 | #include <asm/guarded_storage.h> |
35 | #include <asm/access-regs.h> |
36 | #include <asm/switch_to.h> |
37 | #include <asm/cpu_mf.h> |
38 | #include <asm/processor.h> |
39 | #include <asm/ptrace.h> |
40 | #include <asm/vtimer.h> |
41 | #include <asm/exec.h> |
42 | #include <asm/fpu.h> |
43 | #include <asm/irq.h> |
44 | #include <asm/nmi.h> |
45 | #include <asm/smp.h> |
46 | #include <asm/stacktrace.h> |
47 | #include <asm/runtime_instr.h> |
48 | #include <asm/unwind.h> |
49 | #include "entry.h" |
50 | |
51 | void ret_from_fork(void) asm("ret_from_fork" ); |
52 | |
53 | void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs) |
54 | { |
55 | void (*func)(void *arg); |
56 | |
57 | schedule_tail(prev); |
58 | |
59 | if (!user_mode(regs)) { |
60 | /* Kernel thread */ |
61 | func = (void *)regs->gprs[9]; |
62 | func((void *)regs->gprs[10]); |
63 | } |
64 | clear_pt_regs_flag(regs, PIF_SYSCALL); |
65 | syscall_exit_to_user_mode(regs); |
66 | } |
67 | |
68 | void flush_thread(void) |
69 | { |
70 | } |
71 | |
72 | void arch_setup_new_exec(void) |
73 | { |
74 | if (S390_lowcore.current_pid != current->pid) { |
75 | S390_lowcore.current_pid = current->pid; |
76 | if (test_facility(40)) |
77 | lpp(&S390_lowcore.lpp); |
78 | } |
79 | } |
80 | |
81 | void arch_release_task_struct(struct task_struct *tsk) |
82 | { |
83 | runtime_instr_release(tsk); |
84 | guarded_storage_release(tsk); |
85 | } |
86 | |
87 | int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) |
88 | { |
89 | /* |
90 | * Save the floating-point or vector register state of the current |
91 | * task and set the TIF_FPU flag to lazy restore the FPU register |
92 | * state when returning to user space. |
93 | */ |
94 | save_user_fpu_regs(); |
95 | |
96 | *dst = *src; |
97 | dst->thread.kfpu_flags = 0; |
98 | |
99 | /* |
100 | * Don't transfer over the runtime instrumentation or the guarded |
101 | * storage control block pointers. These fields are cleared here instead |
102 | * of in copy_thread() to avoid premature freeing of associated memory |
103 | * on fork() failure. Wait to clear the RI flag because ->stack still |
104 | * refers to the source thread. |
105 | */ |
106 | dst->thread.ri_cb = NULL; |
107 | dst->thread.gs_cb = NULL; |
108 | dst->thread.gs_bc_cb = NULL; |
109 | |
110 | return 0; |
111 | } |
112 | |
113 | int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) |
114 | { |
115 | unsigned long clone_flags = args->flags; |
116 | unsigned long new_stackp = args->stack; |
117 | unsigned long tls = args->tls; |
118 | struct fake_frame |
119 | { |
120 | struct stack_frame sf; |
121 | struct pt_regs childregs; |
122 | } *frame; |
123 | |
124 | frame = container_of(task_pt_regs(p), struct fake_frame, childregs); |
125 | p->thread.ksp = (unsigned long) frame; |
126 | /* Save access registers to new thread structure. */ |
127 | save_access_regs(&p->thread.acrs[0]); |
128 | /* start new process with ar4 pointing to the correct address space */ |
129 | /* Don't copy debug registers */ |
130 | memset(&p->thread.per_user, 0, sizeof(p->thread.per_user)); |
131 | memset(&p->thread.per_event, 0, sizeof(p->thread.per_event)); |
132 | clear_tsk_thread_flag(tsk: p, flag: TIF_SINGLE_STEP); |
133 | p->thread.per_flags = 0; |
134 | /* Initialize per thread user and system timer values */ |
135 | p->thread.user_timer = 0; |
136 | p->thread.guest_timer = 0; |
137 | p->thread.system_timer = 0; |
138 | p->thread.hardirq_timer = 0; |
139 | p->thread.softirq_timer = 0; |
140 | p->thread.last_break = 1; |
141 | |
142 | frame->sf.back_chain = 0; |
143 | frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; |
144 | frame->sf.gprs[12 - 6] = (unsigned long)p; |
145 | /* new return point is ret_from_fork */ |
146 | frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork; |
147 | /* fake return stack for resume(), don't go back to schedule */ |
148 | frame->sf.gprs[15 - 6] = (unsigned long)frame; |
149 | |
150 | /* Store access registers to kernel stack of new process. */ |
151 | if (unlikely(args->fn)) { |
152 | /* kernel thread */ |
153 | memset(&frame->childregs, 0, sizeof(struct pt_regs)); |
154 | frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | |
155 | PSW_MASK_EXT | PSW_MASK_MCHECK; |
156 | frame->childregs.gprs[9] = (unsigned long)args->fn; |
157 | frame->childregs.gprs[10] = (unsigned long)args->fn_arg; |
158 | frame->childregs.orig_gpr2 = -1; |
159 | frame->childregs.last_break = 1; |
160 | return 0; |
161 | } |
162 | frame->childregs = *current_pt_regs(); |
163 | frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */ |
164 | frame->childregs.flags = 0; |
165 | if (new_stackp) |
166 | frame->childregs.gprs[15] = new_stackp; |
167 | /* |
168 | * Clear the runtime instrumentation flag after the above childregs |
169 | * copy. The CB pointer was already cleared in arch_dup_task_struct(). |
170 | */ |
171 | frame->childregs.psw.mask &= ~PSW_MASK_RI; |
172 | |
173 | /* Set a new TLS ? */ |
174 | if (clone_flags & CLONE_SETTLS) { |
175 | if (is_compat_task()) { |
176 | p->thread.acrs[0] = (unsigned int)tls; |
177 | } else { |
178 | p->thread.acrs[0] = (unsigned int)(tls >> 32); |
179 | p->thread.acrs[1] = (unsigned int)tls; |
180 | } |
181 | } |
182 | /* |
183 | * s390 stores the svc return address in arch_data when calling |
184 | * sigreturn()/restart_syscall() via vdso. 1 means no valid address |
185 | * stored. |
186 | */ |
187 | p->restart_block.arch_data = 1; |
188 | return 0; |
189 | } |
190 | |
191 | void execve_tail(void) |
192 | { |
193 | current->thread.ufpu.fpc = 0; |
194 | fpu_sfpc(0); |
195 | } |
196 | |
197 | struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next) |
198 | { |
199 | save_user_fpu_regs(); |
200 | save_kernel_fpu_regs(&prev->thread); |
201 | save_access_regs(&prev->thread.acrs[0]); |
202 | save_ri_cb(prev->thread.ri_cb); |
203 | save_gs_cb(prev->thread.gs_cb); |
204 | update_cr_regs(next); |
205 | restore_kernel_fpu_regs(&next->thread); |
206 | restore_access_regs(&next->thread.acrs[0]); |
207 | restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb); |
208 | restore_gs_cb(next->thread.gs_cb); |
209 | return __switch_to_asm(prev, next); |
210 | } |
211 | |
212 | unsigned long __get_wchan(struct task_struct *p) |
213 | { |
214 | struct unwind_state state; |
215 | unsigned long ip = 0; |
216 | |
217 | if (!task_stack_page(task: p)) |
218 | return 0; |
219 | |
220 | if (!try_get_task_stack(tsk: p)) |
221 | return 0; |
222 | |
223 | unwind_for_each_frame(&state, p, NULL, 0) { |
224 | if (state.stack_info.type != STACK_TYPE_TASK) { |
225 | ip = 0; |
226 | break; |
227 | } |
228 | |
229 | ip = unwind_get_return_address(state: &state); |
230 | if (!ip) |
231 | break; |
232 | |
233 | if (!in_sched_functions(ip)) |
234 | break; |
235 | } |
236 | |
237 | put_task_stack(tsk: p); |
238 | return ip; |
239 | } |
240 | |
241 | unsigned long arch_align_stack(unsigned long sp) |
242 | { |
243 | if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) |
244 | sp -= get_random_u32_below(PAGE_SIZE); |
245 | return sp & ~0xf; |
246 | } |
247 | |
248 | static inline unsigned long brk_rnd(void) |
249 | { |
250 | return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT; |
251 | } |
252 | |
253 | unsigned long arch_randomize_brk(struct mm_struct *mm) |
254 | { |
255 | unsigned long ret; |
256 | |
257 | ret = PAGE_ALIGN(mm->brk + brk_rnd()); |
258 | return (ret > mm->brk) ? ret : mm->brk; |
259 | } |
260 | |