2 * This file handles the architecture dependent parts of process handling.
4 * Copyright IBM Corp. 1999,2009
5 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
6 * Hartmut Penner <hp@de.ibm.com>,
10 #include <linux/compiler.h>
11 #include <linux/cpu.h>
12 #include <linux/errno.h>
13 #include <linux/sched.h>
14 #include <linux/kernel.h>
17 #include <linux/smp.h>
18 #include <linux/stddef.h>
19 #include <linux/unistd.h>
20 #include <linux/ptrace.h>
21 #include <linux/slab.h>
22 #include <linux/vmalloc.h>
23 #include <linux/user.h>
24 #include <linux/interrupt.h>
25 #include <linux/delay.h>
26 #include <linux/reboot.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/notifier.h>
30 #include <linux/utsname.h>
31 #include <linux/tick.h>
32 #include <linux/elfcore.h>
33 #include <linux/kernel_stat.h>
34 #include <linux/syscalls.h>
35 #include <asm/uaccess.h>
36 #include <asm/pgtable.h>
37 #include <asm/system.h>
39 #include <asm/processor.h>
41 #include <asm/timer.h>
44 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
47 * Return saved PC of a blocked thread. used in kernel/sched.
48 * resume in entry.S does not create a new stack frame, it
49 * just stores the registers %r6-%r15 to the frame given by
50 * schedule. We want to return the address of the caller of
51 * schedule, so we have to walk the backchain one time to
52 * find the frame schedule() store its return address.
54 unsigned long thread_saved_pc(struct task_struct *tsk)
56 struct stack_frame *sf, *low, *high;
58 if (!tsk || !task_stack_page(tsk))
60 low = task_stack_page(tsk);
61 high = (struct stack_frame *) task_pt_regs(tsk);
62 sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
63 if (sf <= low || sf > high)
65 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
66 if (sf <= low || sf > high)
71 extern void s390_handle_mcck(void);
73 * The idle loop on a S390...
75 static void default_idle(void)
77 /* CPU is going idle. */
83 #ifdef CONFIG_HOTPLUG_CPU
84 if (cpu_is_offline(smp_processor_id())) {
85 preempt_enable_no_resched();
90 if (test_thread_flag(TIF_MCCK_PENDING)) {
97 /* Don't trace preempt off for idle. */
98 stop_critical_timings();
99 /* Stop virtual timer and halt the cpu. */
101 /* Reenable preemption tracer. */
102 start_critical_timings();
108 tick_nohz_stop_sched_tick(1);
109 while (!need_resched())
111 tick_nohz_restart_sched_tick();
112 preempt_enable_no_resched();
118 extern void kernel_thread_starter(void);
122 "kernel_thread_starter:\n"
128 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
132 memset(®s, 0, sizeof(regs));
133 regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
134 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
135 regs.gprs[9] = (unsigned long) fn;
136 regs.gprs[10] = (unsigned long) arg;
137 regs.gprs[11] = (unsigned long) do_exit;
140 /* Ok, create the new process.. */
141 return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
142 0, ®s, 0, NULL, NULL);
146 * Free current thread data structures etc..
148 void exit_thread(void)
152 void flush_thread(void)
155 clear_tsk_thread_flag(current, TIF_USEDFPU);
158 void release_thread(struct task_struct *dead_task)
162 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
163 unsigned long unused,
164 struct task_struct *p, struct pt_regs *regs)
168 struct stack_frame sf;
169 struct pt_regs childregs;
172 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
173 p->thread.ksp = (unsigned long) frame;
174 /* Store access registers to kernel stack of new process. */
175 frame->childregs = *regs;
176 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
177 frame->childregs.gprs[15] = new_stackp;
178 frame->sf.back_chain = 0;
180 /* new return point is ret_from_fork */
181 frame->sf.gprs[8] = (unsigned long) ret_from_fork;
183 /* fake return stack for resume(), don't go back to schedule */
184 frame->sf.gprs[9] = (unsigned long) frame;
186 /* Save access registers to new thread structure. */
187 save_access_regs(&p->thread.acrs[0]);
191 * save fprs to current->thread.fp_regs to merge them with
192 * the emulated registers and then copy the result to the child.
194 save_fp_regs(¤t->thread.fp_regs);
195 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs,
196 sizeof(s390_fp_regs));
197 /* Set a new TLS ? */
198 if (clone_flags & CLONE_SETTLS)
199 p->thread.acrs[0] = regs->gprs[6];
200 #else /* CONFIG_64BIT */
201 /* Save the fpu registers to new thread structure. */
202 save_fp_regs(&p->thread.fp_regs);
203 /* Set a new TLS ? */
204 if (clone_flags & CLONE_SETTLS) {
205 if (test_thread_flag(TIF_31BIT)) {
206 p->thread.acrs[0] = (unsigned int) regs->gprs[6];
208 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
209 p->thread.acrs[1] = (unsigned int) regs->gprs[6];
212 #endif /* CONFIG_64BIT */
213 /* start new process with ar4 pointing to the correct address space */
214 p->thread.mm_segment = get_fs();
215 /* Don't copy debug registers */
216 memset(&p->thread.per_info, 0, sizeof(p->thread.per_info));
220 SYSCALL_DEFINE0(fork)
222 struct pt_regs *regs = task_pt_regs(current);
223 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
226 SYSCALL_DEFINE0(clone)
228 struct pt_regs *regs = task_pt_regs(current);
229 unsigned long clone_flags;
231 int __user *parent_tidptr, *child_tidptr;
233 clone_flags = regs->gprs[3];
234 newsp = regs->orig_gpr2;
235 parent_tidptr = (int __user *) regs->gprs[4];
236 child_tidptr = (int __user *) regs->gprs[5];
238 newsp = regs->gprs[15];
239 return do_fork(clone_flags, newsp, regs, 0,
240 parent_tidptr, child_tidptr);
244 * This is trivial, and on the face of it looks like it
245 * could equally well be done in user mode.
247 * Not so, for quite unobvious reasons - register pressure.
248 * In user mode vfork() cannot have a stack frame, and if
249 * done by calling the "clone()" system call directly, you
250 * do not have enough call-clobbered registers to hold all
251 * the information you need.
253 SYSCALL_DEFINE0(vfork)
255 struct pt_regs *regs = task_pt_regs(current);
256 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
257 regs->gprs[15], regs, 0, NULL, NULL);
260 asmlinkage void execve_tail(void)
263 current->ptrace &= ~PT_DTRACE;
264 task_unlock(current);
265 current->thread.fp_regs.fpc = 0;
266 if (MACHINE_HAS_IEEE)
267 asm volatile("sfpc %0,%0" : : "d" (0));
271 * sys_execve() executes a new program.
273 SYSCALL_DEFINE0(execve)
275 struct pt_regs *regs = task_pt_regs(current);
277 unsigned long result;
280 filename = getname((char __user *) regs->orig_gpr2);
281 if (IS_ERR(filename)) {
282 result = PTR_ERR(filename);
285 rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
286 (char __user * __user *) regs->gprs[4], regs);
292 result = regs->gprs[2];
300 * fill in the FPU structure for a core dump.
302 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
306 * save fprs to current->thread.fp_regs to merge them with
307 * the emulated registers and then copy the result to the dump.
309 save_fp_regs(¤t->thread.fp_regs);
310 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs));
311 #else /* CONFIG_64BIT */
312 save_fp_regs(fpregs);
313 #endif /* CONFIG_64BIT */
317 unsigned long get_wchan(struct task_struct *p)
319 struct stack_frame *sf, *low, *high;
320 unsigned long return_address;
323 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
325 low = task_stack_page(p);
326 high = (struct stack_frame *) task_pt_regs(p);
327 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
328 if (sf <= low || sf > high)
330 for (count = 0; count < 16; count++) {
331 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
332 if (sf <= low || sf > high)
334 return_address = sf->gprs[8] & PSW_ADDR_INSN;
335 if (!in_sched_functions(return_address))
336 return return_address;