arch/s390/kernel/process.c

   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/errno.h>
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/fs.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/tick.h>
  31 #include <linux/elfcore.h>
  32 #include <linux/kernel_stat.h>
  33 #include <linux/syscalls.h>
  34 #include <linux/compat.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/pgtable.h>
  37 #include <asm/system.h>
  38 #include <asm/io.h>
  39 #include <asm/processor.h>
  40 #include <asm/irq.h>
  41 #include <asm/timer.h>
  42 #include <asm/nmi.h>
  43 #include "entry.h"
  44
  45 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  46
  47 /*
  48  * Return saved PC of a blocked thread. used in kernel/sched.
  49  * resume in entry.S does not create a new stack frame, it
  50  * just stores the registers %r6-%r15 to the frame given by
  51  * schedule. We want to return the address of the caller of
  52  * schedule, so we have to walk the backchain one time to
  53  * find the frame schedule() store its return address.
  54  */
  55 unsigned long thread_saved_pc(struct task_struct *tsk)
  56 {
  57         struct stack_frame *sf, *low, *high;
  58
  59         if (!tsk || !task_stack_page(tsk))
  60                 return 0;
  61         low = task_stack_page(tsk);
  62         high = (struct stack_frame *) task_pt_regs(tsk);
  63         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  64         if (sf <= low || sf > high)
  65                 return 0;
  66         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  67         if (sf <= low || sf > high)
  68                 return 0;
  69         return sf->gprs[8];
  70 }
  71
  72 /*
  73  * The idle loop on a S390...
  74  */
  75 static void default_idle(void)
  76 {
  77         /* CPU is going idle. */
  78         local_irq_disable();
  79         if (need_resched()) {
  80                 local_irq_enable();
  81                 return;
  82         }
  83 #ifdef CONFIG_HOTPLUG_CPU
  84         if (cpu_is_offline(smp_processor_id())) {
  85                 preempt_enable_no_resched();
  86                 cpu_die();
  87         }
  88 #endif
  89         local_mcck_disable();
  90         if (test_thread_flag(TIF_MCCK_PENDING)) {
  91                 local_mcck_enable();
  92                 local_irq_enable();
  93                 s390_handle_mcck();
  94                 return;
  95         }
  96         trace_hardirqs_on();
  97         /* Don't trace preempt off for idle. */
  98         stop_critical_timings();
  99         /* Stop virtual timer and halt the cpu. */
 100         vtime_stop_cpu();
 101         /* Reenable preemption tracer. */
 102         start_critical_timings();
 103 }
 104
 105 void cpu_idle(void)
 106 {
 107         for (;;) {
 108                 tick_nohz_stop_sched_tick(1);
 109                 while (!need_resched())
 110                         default_idle();
 111                 tick_nohz_restart_sched_tick();
 112                 preempt_enable_no_resched();
 113                 schedule();
 114                 preempt_disable();
 115         }
 116 }
 117
 118 extern void kernel_thread_starter(void);
 119
 120 asm(
 121         ".align 4\n"
 122         "kernel_thread_starter:\n"
 123         "    la    2,0(10)\n"
 124         "    basr  14,9\n"
 125         "    la    2,0\n"
 126         "    br    11\n");
 127
 128 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 129 {
 130         struct pt_regs regs;
 131
 132         memset(&regs, 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;
 138         regs.orig_gpr2 = -1;
 139
 140         /* Ok, create the new process.. */
 141         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 142                        0, &regs, 0, NULL, NULL);
 143 }
 144 EXPORT_SYMBOL(kernel_thread);
 145
 146 /*
 147  * Free current thread data structures etc..
 148  */
 149 void exit_thread(void)
 150 {
 151 }
 152
 153 void flush_thread(void)
 154 {
 155         clear_used_math();
 156         clear_tsk_thread_flag(current, TIF_USEDFPU);
 157 }
 158
 159 void release_thread(struct task_struct *dead_task)
 160 {
 161 }
 162
 163 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 164                 unsigned long unused,
 165                 struct task_struct *p, struct pt_regs *regs)
 166 {
 167         struct thread_info *ti;
 168         struct fake_frame
 169         {
 170                 struct stack_frame sf;
 171                 struct pt_regs childregs;
 172         } *frame;
 173
 174         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 175         p->thread.ksp = (unsigned long) frame;
 176         /* Store access registers to kernel stack of new process. */
 177         frame->childregs = *regs;
 178         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 179         frame->childregs.gprs[15] = new_stackp;
 180         frame->sf.back_chain = 0;
 181
 182         /* new return point is ret_from_fork */
 183         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 184
 185         /* fake return stack for resume(), don't go back to schedule */
 186         frame->sf.gprs[9] = (unsigned long) frame;
 187
 188         /* Save access registers to new thread structure. */
 189         save_access_regs(&p->thread.acrs[0]);
 190
 191 #ifndef CONFIG_64BIT
 192         /*
 193          * save fprs to current->thread.fp_regs to merge them with
 194          * the emulated registers and then copy the result to the child.
 195          */
 196         save_fp_regs(&current->thread.fp_regs);
 197         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 198                sizeof(s390_fp_regs));
 199         /* Set a new TLS ?  */
 200         if (clone_flags & CLONE_SETTLS)
 201                 p->thread.acrs[0] = regs->gprs[6];
 202 #else /* CONFIG_64BIT */
 203         /* Save the fpu registers to new thread structure. */
 204         save_fp_regs(&p->thread.fp_regs);
 205         /* Set a new TLS ?  */
 206         if (clone_flags & CLONE_SETTLS) {
 207                 if (is_compat_task()) {
 208                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 209                 } else {
 210                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 211                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 212                 }
 213         }
 214 #endif /* CONFIG_64BIT */
 215         /* start new process with ar4 pointing to the correct address space */
 216         p->thread.mm_segment = get_fs();
 217         /* Don't copy debug registers */
 218         memset(&p->thread.per_info, 0, sizeof(p->thread.per_info));
 219         /* Initialize per thread user and system timer values */
 220         ti = task_thread_info(p);
 221         ti->user_timer = 0;
 222         ti->system_timer = 0;
 223         return 0;
 224 }
 225
 226 SYSCALL_DEFINE0(fork)
 227 {
 228         struct pt_regs *regs = task_pt_regs(current);
 229         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 230 }
 231
 232 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
 233                 int __user *, parent_tidptr, int __user *, child_tidptr)
 234 {
 235         struct pt_regs *regs = task_pt_regs(current);
 236
 237         if (!newsp)
 238                 newsp = regs->gprs[15];
 239         return do_fork(clone_flags, newsp, regs, 0,
 240                        parent_tidptr, child_tidptr);
 241 }
 242
 243 /*
 244  * This is trivial, and on the face of it looks like it
 245  * could equally well be done in user mode.
 246  *
 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.
 252  */
 253 SYSCALL_DEFINE0(vfork)
 254 {
 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);
 258 }
 259
 260 asmlinkage void execve_tail(void)
 261 {
 262         current->thread.fp_regs.fpc = 0;
 263         if (MACHINE_HAS_IEEE)
 264                 asm volatile("sfpc %0,%0" : : "d" (0));
 265 }
 266
 267 /*
 268  * sys_execve() executes a new program.
 269  */
 270 SYSCALL_DEFINE3(execve, char __user *, name, char __user * __user *, argv,
 271                 char __user * __user *, envp)
 272 {
 273         struct pt_regs *regs = task_pt_regs(current);
 274         char *filename;
 275         long rc;
 276
 277         filename = getname(name);
 278         rc = PTR_ERR(filename);
 279         if (IS_ERR(filename))
 280                 return rc;
 281         rc = do_execve(filename, argv, envp, regs);
 282         if (rc)
 283                 goto out;
 284         execve_tail();
 285         rc = regs->gprs[2];
 286 out:
 287         putname(filename);
 288         return rc;
 289 }
 290
 291 /*
 292  * fill in the FPU structure for a core dump.
 293  */
 294 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 295 {
 296 #ifndef CONFIG_64BIT
 297         /*
 298          * save fprs to current->thread.fp_regs to merge them with
 299          * the emulated registers and then copy the result to the dump.
 300          */
 301         save_fp_regs(&current->thread.fp_regs);
 302         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 303 #else /* CONFIG_64BIT */
 304         save_fp_regs(fpregs);
 305 #endif /* CONFIG_64BIT */
 306         return 1;
 307 }
 308 EXPORT_SYMBOL(dump_fpu);
 309
 310 unsigned long get_wchan(struct task_struct *p)
 311 {
 312         struct stack_frame *sf, *low, *high;
 313         unsigned long return_address;
 314         int count;
 315
 316         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 317                 return 0;
 318         low = task_stack_page(p);
 319         high = (struct stack_frame *) task_pt_regs(p);
 320         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 321         if (sf <= low || sf > high)
 322                 return 0;
 323         for (count = 0; count < 16; count++) {
 324                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 325                 if (sf <= low || sf > high)
 326                         return 0;
 327                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 328                 if (!in_sched_functions(return_address))
 329                         return return_address;
 330         }
 331         return 0;
 332 }