1 // SPDX-License-Identifier: GPL-2.0
3 * This file handles the architecture dependent parts of process handling.
5 * Copyright IBM Corp. 1999, 2009
6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 * Hartmut Penner <hp@de.ibm.com>,
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>
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>
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>
46 #include <asm/stacktrace.h>
47 #include <asm/runtime_instr.h>
48 #include <asm/unwind.h>
51 void ret_from_fork(void) asm("ret_from_fork");
53 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
55 void (*func)(void *arg);
59 if (!user_mode(regs)) {
61 func = (void *)regs->gprs[9];
62 func((void *)regs->gprs[10]);
64 clear_pt_regs_flag(regs, PIF_SYSCALL);
65 syscall_exit_to_user_mode(regs);
68 void flush_thread(void)
72 void arch_setup_new_exec(void)
74 if (get_lowcore()->current_pid != current->pid) {
75 get_lowcore()->current_pid = current->pid;
76 if (test_facility(40))
77 lpp(&get_lowcore()->lpp);
81 void arch_release_task_struct(struct task_struct *tsk)
83 runtime_instr_release(tsk);
84 guarded_storage_release(tsk);
87 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
92 dst->thread.kfpu_flags = 0;
95 * Don't transfer over the runtime instrumentation or the guarded
96 * storage control block pointers. These fields are cleared here instead
97 * of in copy_thread() to avoid premature freeing of associated memory
98 * on fork() failure. Wait to clear the RI flag because ->stack still
99 * refers to the source thread.
101 dst->thread.ri_cb = NULL;
102 dst->thread.gs_cb = NULL;
103 dst->thread.gs_bc_cb = NULL;
108 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
110 unsigned long clone_flags = args->flags;
111 unsigned long new_stackp = args->stack;
112 unsigned long tls = args->tls;
115 struct stack_frame sf;
116 struct pt_regs childregs;
119 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
120 p->thread.ksp = (unsigned long) frame;
121 /* Save access registers to new thread structure. */
122 save_access_regs(&p->thread.acrs[0]);
123 /* start new process with ar4 pointing to the correct address space */
124 /* Don't copy debug registers */
125 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
126 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
127 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
128 p->thread.per_flags = 0;
129 /* Initialize per thread user and system timer values */
130 p->thread.user_timer = 0;
131 p->thread.guest_timer = 0;
132 p->thread.system_timer = 0;
133 p->thread.hardirq_timer = 0;
134 p->thread.softirq_timer = 0;
135 p->thread.last_break = 1;
137 frame->sf.back_chain = 0;
138 frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs;
139 frame->sf.gprs[12 - 6] = (unsigned long)p;
140 /* new return point is ret_from_fork */
141 frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;
142 /* fake return stack for resume(), don't go back to schedule */
143 frame->sf.gprs[15 - 6] = (unsigned long)frame;
145 /* Store access registers to kernel stack of new process. */
146 if (unlikely(args->fn)) {
148 memset(&frame->childregs, 0, sizeof(struct pt_regs));
149 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO |
150 PSW_MASK_EXT | PSW_MASK_MCHECK;
151 frame->childregs.gprs[9] = (unsigned long)args->fn;
152 frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
153 frame->childregs.orig_gpr2 = -1;
154 frame->childregs.last_break = 1;
157 frame->childregs = *current_pt_regs();
158 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
159 frame->childregs.flags = 0;
161 frame->childregs.gprs[15] = new_stackp;
163 * Clear the runtime instrumentation flag after the above childregs
164 * copy. The CB pointer was already cleared in arch_dup_task_struct().
166 frame->childregs.psw.mask &= ~PSW_MASK_RI;
168 /* Set a new TLS ? */
169 if (clone_flags & CLONE_SETTLS) {
170 if (is_compat_task()) {
171 p->thread.acrs[0] = (unsigned int)tls;
173 p->thread.acrs[0] = (unsigned int)(tls >> 32);
174 p->thread.acrs[1] = (unsigned int)tls;
178 * s390 stores the svc return address in arch_data when calling
179 * sigreturn()/restart_syscall() via vdso. 1 means no valid address
182 p->restart_block.arch_data = 1;
186 void execve_tail(void)
188 current->thread.ufpu.fpc = 0;
192 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
194 save_user_fpu_regs();
195 save_kernel_fpu_regs(&prev->thread);
196 save_access_regs(&prev->thread.acrs[0]);
197 save_ri_cb(prev->thread.ri_cb);
198 save_gs_cb(prev->thread.gs_cb);
199 update_cr_regs(next);
200 restore_kernel_fpu_regs(&next->thread);
201 restore_access_regs(&next->thread.acrs[0]);
202 restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);
203 restore_gs_cb(next->thread.gs_cb);
204 return __switch_to_asm(prev, next);
207 unsigned long __get_wchan(struct task_struct *p)
209 struct unwind_state state;
210 unsigned long ip = 0;
212 if (!task_stack_page(p))
215 if (!try_get_task_stack(p))
218 unwind_for_each_frame(&state, p, NULL, 0) {
219 if (state.stack_info.type != STACK_TYPE_TASK) {
224 ip = unwind_get_return_address(&state);
228 if (!in_sched_functions(ip))
236 unsigned long arch_align_stack(unsigned long sp)
238 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
239 sp -= get_random_u32_below(PAGE_SIZE);
243 static inline unsigned long brk_rnd(void)
245 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
248 unsigned long arch_randomize_brk(struct mm_struct *mm)
252 ret = PAGE_ALIGN(mm->brk + brk_rnd());
253 return (ret > mm->brk) ? ret : mm->brk;