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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 <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
45asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
46
47extern void kernel_thread_starter(void);
48
49void flush_thread(void)
50{
51}
52
53void 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
62void arch_release_task_struct(struct task_struct *tsk)
63{
64 runtime_instr_release(tsk);
65 guarded_storage_release(tsk);
66}
67
68int 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
82int 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
155asmlinkage 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 */
164int 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}
177EXPORT_SYMBOL(dump_fpu);
178
179unsigned 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 }
208out:
209 put_task_stack(p);
210 return return_address;
211}
212
213unsigned 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
220static inline unsigned long brk_rnd(void)
221{
222 return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
223}
224
225unsigned 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
233void 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}
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}