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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
51void ret_from_fork(void) asm("ret_from_fork");
52
53void __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
68void flush_thread(void)
69{
70}
71
72void arch_setup_new_exec(void)
73{
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);
78 }
79}
80
81void arch_release_task_struct(struct task_struct *tsk)
82{
83 runtime_instr_release(tsk);
84 guarded_storage_release(tsk);
85}
86
87int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
88{
89 save_user_fpu_regs();
90
91 *dst = *src;
92 dst->thread.kfpu_flags = 0;
93
94 /*
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.
100 */
101 dst->thread.ri_cb = NULL;
102 dst->thread.gs_cb = NULL;
103 dst->thread.gs_bc_cb = NULL;
104
105 return 0;
106}
107
108int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
109{
110 unsigned long clone_flags = args->flags;
111 unsigned long new_stackp = args->stack;
112 unsigned long tls = args->tls;
113 struct fake_frame
114 {
115 struct stack_frame sf;
116 struct pt_regs childregs;
117 } *frame;
118
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;
136
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;
144
145 /* Store access registers to kernel stack of new process. */
146 if (unlikely(args->fn)) {
147 /* kernel thread */
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;
155 return 0;
156 }
157 frame->childregs = *current_pt_regs();
158 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
159 frame->childregs.flags = 0;
160 if (new_stackp)
161 frame->childregs.gprs[15] = new_stackp;
162 /*
163 * Clear the runtime instrumentation flag after the above childregs
164 * copy. The CB pointer was already cleared in arch_dup_task_struct().
165 */
166 frame->childregs.psw.mask &= ~PSW_MASK_RI;
167
168 /* Set a new TLS ? */
169 if (clone_flags & CLONE_SETTLS) {
170 if (is_compat_task()) {
171 p->thread.acrs[0] = (unsigned int)tls;
172 } else {
173 p->thread.acrs[0] = (unsigned int)(tls >> 32);
174 p->thread.acrs[1] = (unsigned int)tls;
175 }
176 }
177 /*
178 * s390 stores the svc return address in arch_data when calling
179 * sigreturn()/restart_syscall() via vdso. 1 means no valid address
180 * stored.
181 */
182 p->restart_block.arch_data = 1;
183 return 0;
184}
185
186void execve_tail(void)
187{
188 current->thread.ufpu.fpc = 0;
189 fpu_sfpc(0);
190}
191
192struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
193{
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);
205}
206
207unsigned long __get_wchan(struct task_struct *p)
208{
209 struct unwind_state state;
210 unsigned long ip = 0;
211
212 if (!task_stack_page(p))
213 return 0;
214
215 if (!try_get_task_stack(p))
216 return 0;
217
218 unwind_for_each_frame(&state, p, NULL, 0) {
219 if (state.stack_info.type != STACK_TYPE_TASK) {
220 ip = 0;
221 break;
222 }
223
224 ip = unwind_get_return_address(&state);
225 if (!ip)
226 break;
227
228 if (!in_sched_functions(ip))
229 break;
230 }
231
232 put_task_stack(p);
233 return ip;
234}
235
236unsigned long arch_align_stack(unsigned long sp)
237{
238 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
239 sp -= get_random_u32_below(PAGE_SIZE);
240 return sp & ~0xf;
241}
242
243static inline unsigned long brk_rnd(void)
244{
245 return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
246}
247
248unsigned long arch_randomize_brk(struct mm_struct *mm)
249{
250 unsigned long ret;
251
252 ret = PAGE_ALIGN(mm->brk + brk_rnd());
253 return (ret > mm->brk) ? ret : mm->brk;
254}
1/*
2 * This file handles the architecture dependent parts of process handling.
3 *
4 * Copyright IBM Corp. 1999,2009
5 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
6 * Hartmut Penner <hp@de.ibm.com>,
7 * Denis Joseph Barrow,
8 */
9
10#include <linux/compiler.h>
11#include <linux/cpu.h>
12#include <linux/sched.h>
13#include <linux/kernel.h>
14#include <linux/mm.h>
15#include <linux/elfcore.h>
16#include <linux/smp.h>
17#include <linux/slab.h>
18#include <linux/interrupt.h>
19#include <linux/tick.h>
20#include <linux/personality.h>
21#include <linux/syscalls.h>
22#include <linux/compat.h>
23#include <linux/kprobes.h>
24#include <linux/random.h>
25#include <linux/module.h>
26#include <asm/io.h>
27#include <asm/processor.h>
28#include <asm/irq.h>
29#include <asm/timer.h>
30#include <asm/nmi.h>
31#include <asm/smp.h>
32#include <asm/switch_to.h>
33#include "entry.h"
34
35asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
36
37/*
38 * Return saved PC of a blocked thread. used in kernel/sched.
39 * resume in entry.S does not create a new stack frame, it
40 * just stores the registers %r6-%r15 to the frame given by
41 * schedule. We want to return the address of the caller of
42 * schedule, so we have to walk the backchain one time to
43 * find the frame schedule() store its return address.
44 */
45unsigned long thread_saved_pc(struct task_struct *tsk)
46{
47 struct stack_frame *sf, *low, *high;
48
49 if (!tsk || !task_stack_page(tsk))
50 return 0;
51 low = task_stack_page(tsk);
52 high = (struct stack_frame *) task_pt_regs(tsk);
53 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
54 if (sf <= low || sf > high)
55 return 0;
56 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
57 if (sf <= low || sf > high)
58 return 0;
59 return sf->gprs[8];
60}
61
62/*
63 * The idle loop on a S390...
64 */
65static void default_idle(void)
66{
67 if (cpu_is_offline(smp_processor_id()))
68 cpu_die();
69 local_irq_disable();
70 if (need_resched()) {
71 local_irq_enable();
72 return;
73 }
74 local_mcck_disable();
75 if (test_thread_flag(TIF_MCCK_PENDING)) {
76 local_mcck_enable();
77 local_irq_enable();
78 return;
79 }
80 /* Halt the cpu and keep track of cpu time accounting. */
81 vtime_stop_cpu();
82}
83
84void cpu_idle(void)
85{
86 for (;;) {
87 tick_nohz_idle_enter();
88 rcu_idle_enter();
89 while (!need_resched() && !test_thread_flag(TIF_MCCK_PENDING))
90 default_idle();
91 rcu_idle_exit();
92 tick_nohz_idle_exit();
93 if (test_thread_flag(TIF_MCCK_PENDING))
94 s390_handle_mcck();
95 schedule_preempt_disabled();
96 }
97}
98
99extern void __kprobes kernel_thread_starter(void);
100
101asm(
102 ".section .kprobes.text, \"ax\"\n"
103 ".global kernel_thread_starter\n"
104 "kernel_thread_starter:\n"
105 " la 2,0(10)\n"
106 " basr 14,9\n"
107 " la 2,0\n"
108 " br 11\n"
109 ".previous\n");
110
111int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
112{
113 struct pt_regs regs;
114
115 memset(®s, 0, sizeof(regs));
116 regs.psw.mask = psw_kernel_bits |
117 PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
118 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
119 regs.gprs[9] = (unsigned long) fn;
120 regs.gprs[10] = (unsigned long) arg;
121 regs.gprs[11] = (unsigned long) do_exit;
122 regs.orig_gpr2 = -1;
123
124 /* Ok, create the new process.. */
125 return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
126 0, ®s, 0, NULL, NULL);
127}
128EXPORT_SYMBOL(kernel_thread);
129
130/*
131 * Free current thread data structures etc..
132 */
133void exit_thread(void)
134{
135}
136
137void flush_thread(void)
138{
139}
140
141void release_thread(struct task_struct *dead_task)
142{
143}
144
145int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
146 unsigned long unused,
147 struct task_struct *p, struct pt_regs *regs)
148{
149 struct thread_info *ti;
150 struct fake_frame
151 {
152 struct stack_frame sf;
153 struct pt_regs childregs;
154 } *frame;
155
156 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
157 p->thread.ksp = (unsigned long) frame;
158 /* Store access registers to kernel stack of new process. */
159 frame->childregs = *regs;
160 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
161 frame->childregs.gprs[15] = new_stackp;
162 frame->sf.back_chain = 0;
163
164 /* new return point is ret_from_fork */
165 frame->sf.gprs[8] = (unsigned long) ret_from_fork;
166
167 /* fake return stack for resume(), don't go back to schedule */
168 frame->sf.gprs[9] = (unsigned long) frame;
169
170 /* Save access registers to new thread structure. */
171 save_access_regs(&p->thread.acrs[0]);
172
173#ifndef CONFIG_64BIT
174 /*
175 * save fprs to current->thread.fp_regs to merge them with
176 * the emulated registers and then copy the result to the child.
177 */
178 save_fp_regs(¤t->thread.fp_regs);
179 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs,
180 sizeof(s390_fp_regs));
181 /* Set a new TLS ? */
182 if (clone_flags & CLONE_SETTLS)
183 p->thread.acrs[0] = regs->gprs[6];
184#else /* CONFIG_64BIT */
185 /* Save the fpu registers to new thread structure. */
186 save_fp_regs(&p->thread.fp_regs);
187 /* Set a new TLS ? */
188 if (clone_flags & CLONE_SETTLS) {
189 if (is_compat_task()) {
190 p->thread.acrs[0] = (unsigned int) regs->gprs[6];
191 } else {
192 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
193 p->thread.acrs[1] = (unsigned int) regs->gprs[6];
194 }
195 }
196#endif /* CONFIG_64BIT */
197 /* start new process with ar4 pointing to the correct address space */
198 p->thread.mm_segment = get_fs();
199 /* Don't copy debug registers */
200 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
201 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
202 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
203 clear_tsk_thread_flag(p, TIF_PER_TRAP);
204 /* Initialize per thread user and system timer values */
205 ti = task_thread_info(p);
206 ti->user_timer = 0;
207 ti->system_timer = 0;
208 return 0;
209}
210
211SYSCALL_DEFINE0(fork)
212{
213 struct pt_regs *regs = task_pt_regs(current);
214 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
215}
216
217SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
218 int __user *, parent_tidptr, int __user *, child_tidptr)
219{
220 struct pt_regs *regs = task_pt_regs(current);
221
222 if (!newsp)
223 newsp = regs->gprs[15];
224 return do_fork(clone_flags, newsp, regs, 0,
225 parent_tidptr, child_tidptr);
226}
227
228/*
229 * This is trivial, and on the face of it looks like it
230 * could equally well be done in user mode.
231 *
232 * Not so, for quite unobvious reasons - register pressure.
233 * In user mode vfork() cannot have a stack frame, and if
234 * done by calling the "clone()" system call directly, you
235 * do not have enough call-clobbered registers to hold all
236 * the information you need.
237 */
238SYSCALL_DEFINE0(vfork)
239{
240 struct pt_regs *regs = task_pt_regs(current);
241 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
242 regs->gprs[15], regs, 0, NULL, NULL);
243}
244
245asmlinkage void execve_tail(void)
246{
247 current->thread.fp_regs.fpc = 0;
248 if (MACHINE_HAS_IEEE)
249 asm volatile("sfpc %0,%0" : : "d" (0));
250}
251
252/*
253 * sys_execve() executes a new program.
254 */
255SYSCALL_DEFINE3(execve, const char __user *, name,
256 const char __user *const __user *, argv,
257 const char __user *const __user *, envp)
258{
259 struct pt_regs *regs = task_pt_regs(current);
260 char *filename;
261 long rc;
262
263 filename = getname(name);
264 rc = PTR_ERR(filename);
265 if (IS_ERR(filename))
266 return rc;
267 rc = do_execve(filename, argv, envp, regs);
268 if (rc)
269 goto out;
270 execve_tail();
271 rc = regs->gprs[2];
272out:
273 putname(filename);
274 return rc;
275}
276
277/*
278 * fill in the FPU structure for a core dump.
279 */
280int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
281{
282#ifndef CONFIG_64BIT
283 /*
284 * save fprs to current->thread.fp_regs to merge them with
285 * the emulated registers and then copy the result to the dump.
286 */
287 save_fp_regs(¤t->thread.fp_regs);
288 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs));
289#else /* CONFIG_64BIT */
290 save_fp_regs(fpregs);
291#endif /* CONFIG_64BIT */
292 return 1;
293}
294EXPORT_SYMBOL(dump_fpu);
295
296unsigned long get_wchan(struct task_struct *p)
297{
298 struct stack_frame *sf, *low, *high;
299 unsigned long return_address;
300 int count;
301
302 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
303 return 0;
304 low = task_stack_page(p);
305 high = (struct stack_frame *) task_pt_regs(p);
306 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
307 if (sf <= low || sf > high)
308 return 0;
309 for (count = 0; count < 16; count++) {
310 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
311 if (sf <= low || sf > high)
312 return 0;
313 return_address = sf->gprs[8] & PSW_ADDR_INSN;
314 if (!in_sched_functions(return_address))
315 return return_address;
316 }
317 return 0;
318}
319
320unsigned long arch_align_stack(unsigned long sp)
321{
322 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
323 sp -= get_random_int() & ~PAGE_MASK;
324 return sp & ~0xf;
325}
326
327static inline unsigned long brk_rnd(void)
328{
329 /* 8MB for 32bit, 1GB for 64bit */
330 if (is_32bit_task())
331 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
332 else
333 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
334}
335
336unsigned long arch_randomize_brk(struct mm_struct *mm)
337{
338 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
339
340 if (ret < mm->brk)
341 return mm->brk;
342 return ret;
343}
344
345unsigned long randomize_et_dyn(unsigned long base)
346{
347 unsigned long ret = PAGE_ALIGN(base + brk_rnd());
348
349 if (!(current->flags & PF_RANDOMIZE))
350 return base;
351 if (ret < base)
352 return base;
353 return ret;
354}