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/sched.h>
13 #include <linux/kernel.h>
15 #include <linux/smp.h>
16 #include <linux/slab.h>
17 #include <linux/interrupt.h>
18 #include <linux/tick.h>
19 #include <linux/personality.h>
20 #include <linux/syscalls.h>
21 #include <linux/compat.h>
22 #include <linux/kprobes.h>
23 #include <linux/random.h>
24 #include <linux/module.h>
25 #include <asm/system.h>
27 #include <asm/processor.h>
29 #include <asm/timer.h>
31 #include <asm/compat.h>
35 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
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.
45 unsigned long thread_saved_pc(struct task_struct *tsk)
47 struct stack_frame *sf, *low, *high;
49 if (!tsk || !task_stack_page(tsk))
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)
56 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
57 if (sf <= low || sf > high)
63 * The idle loop on a S390...
65 static void default_idle(void)
67 if (cpu_is_offline(smp_processor_id()))
75 if (test_thread_flag(TIF_MCCK_PENDING)) {
82 /* Don't trace preempt off for idle. */
83 stop_critical_timings();
84 /* Stop virtual timer and halt the cpu. */
86 /* Reenable preemption tracer. */
87 start_critical_timings();
93 tick_nohz_stop_sched_tick(1);
94 while (!need_resched())
96 tick_nohz_restart_sched_tick();
97 preempt_enable_no_resched();
103 extern void __kprobes kernel_thread_starter(void);
106 ".section .kprobes.text, \"ax\"\n"
107 ".global kernel_thread_starter\n"
108 "kernel_thread_starter:\n"
115 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
119 memset(®s, 0, sizeof(regs));
120 regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
121 regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
122 regs.gprs[9] = (unsigned long) fn;
123 regs.gprs[10] = (unsigned long) arg;
124 regs.gprs[11] = (unsigned long) do_exit;
127 /* Ok, create the new process.. */
128 return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
129 0, ®s, 0, NULL, NULL);
131 EXPORT_SYMBOL(kernel_thread);
134 * Free current thread data structures etc..
136 void exit_thread(void)
140 void flush_thread(void)
144 void release_thread(struct task_struct *dead_task)
148 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
149 unsigned long unused,
150 struct task_struct *p, struct pt_regs *regs)
152 struct thread_info *ti;
155 struct stack_frame sf;
156 struct pt_regs childregs;
159 frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
160 p->thread.ksp = (unsigned long) frame;
161 /* Store access registers to kernel stack of new process. */
162 frame->childregs = *regs;
163 frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
164 frame->childregs.gprs[15] = new_stackp;
165 frame->sf.back_chain = 0;
167 /* new return point is ret_from_fork */
168 frame->sf.gprs[8] = (unsigned long) ret_from_fork;
170 /* fake return stack for resume(), don't go back to schedule */
171 frame->sf.gprs[9] = (unsigned long) frame;
173 /* Save access registers to new thread structure. */
174 save_access_regs(&p->thread.acrs[0]);
178 * save fprs to current->thread.fp_regs to merge them with
179 * the emulated registers and then copy the result to the child.
181 save_fp_regs(¤t->thread.fp_regs);
182 memcpy(&p->thread.fp_regs, ¤t->thread.fp_regs,
183 sizeof(s390_fp_regs));
184 /* Set a new TLS ? */
185 if (clone_flags & CLONE_SETTLS)
186 p->thread.acrs[0] = regs->gprs[6];
187 #else /* CONFIG_64BIT */
188 /* Save the fpu registers to new thread structure. */
189 save_fp_regs(&p->thread.fp_regs);
190 /* Set a new TLS ? */
191 if (clone_flags & CLONE_SETTLS) {
192 if (is_compat_task()) {
193 p->thread.acrs[0] = (unsigned int) regs->gprs[6];
195 p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
196 p->thread.acrs[1] = (unsigned int) regs->gprs[6];
199 #endif /* CONFIG_64BIT */
200 /* start new process with ar4 pointing to the correct address space */
201 p->thread.mm_segment = get_fs();
202 /* Don't copy debug registers */
203 memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
204 memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
205 clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
206 clear_tsk_thread_flag(p, TIF_PER_TRAP);
207 /* Initialize per thread user and system timer values */
208 ti = task_thread_info(p);
210 ti->system_timer = 0;
214 SYSCALL_DEFINE0(fork)
216 struct pt_regs *regs = task_pt_regs(current);
217 return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
220 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
221 int __user *, parent_tidptr, int __user *, child_tidptr)
223 struct pt_regs *regs = task_pt_regs(current);
226 newsp = regs->gprs[15];
227 return do_fork(clone_flags, newsp, regs, 0,
228 parent_tidptr, child_tidptr);
232 * This is trivial, and on the face of it looks like it
233 * could equally well be done in user mode.
235 * Not so, for quite unobvious reasons - register pressure.
236 * In user mode vfork() cannot have a stack frame, and if
237 * done by calling the "clone()" system call directly, you
238 * do not have enough call-clobbered registers to hold all
239 * the information you need.
241 SYSCALL_DEFINE0(vfork)
243 struct pt_regs *regs = task_pt_regs(current);
244 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
245 regs->gprs[15], regs, 0, NULL, NULL);
248 asmlinkage void execve_tail(void)
250 current->thread.fp_regs.fpc = 0;
251 if (MACHINE_HAS_IEEE)
252 asm volatile("sfpc %0,%0" : : "d" (0));
256 * sys_execve() executes a new program.
258 SYSCALL_DEFINE3(execve, const char __user *, name,
259 const char __user *const __user *, argv,
260 const char __user *const __user *, envp)
262 struct pt_regs *regs = task_pt_regs(current);
266 filename = getname(name);
267 rc = PTR_ERR(filename);
268 if (IS_ERR(filename))
270 rc = do_execve(filename, argv, envp, regs);
281 * fill in the FPU structure for a core dump.
283 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
287 * save fprs to current->thread.fp_regs to merge them with
288 * the emulated registers and then copy the result to the dump.
290 save_fp_regs(¤t->thread.fp_regs);
291 memcpy(fpregs, ¤t->thread.fp_regs, sizeof(s390_fp_regs));
292 #else /* CONFIG_64BIT */
293 save_fp_regs(fpregs);
294 #endif /* CONFIG_64BIT */
297 EXPORT_SYMBOL(dump_fpu);
299 unsigned long get_wchan(struct task_struct *p)
301 struct stack_frame *sf, *low, *high;
302 unsigned long return_address;
305 if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
307 low = task_stack_page(p);
308 high = (struct stack_frame *) task_pt_regs(p);
309 sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
310 if (sf <= low || sf > high)
312 for (count = 0; count < 16; count++) {
313 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
314 if (sf <= low || sf > high)
316 return_address = sf->gprs[8] & PSW_ADDR_INSN;
317 if (!in_sched_functions(return_address))
318 return return_address;
323 unsigned long arch_align_stack(unsigned long sp)
325 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
326 sp -= get_random_int() & ~PAGE_MASK;
330 static inline unsigned long brk_rnd(void)
332 /* 8MB for 32bit, 1GB for 64bit */
334 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
336 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
339 unsigned long arch_randomize_brk(struct mm_struct *mm)
341 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
348 unsigned long randomize_et_dyn(unsigned long base)
350 unsigned long ret = PAGE_ALIGN(base + brk_rnd());
352 if (!(current->flags & PF_RANDOMIZE))