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/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mm.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>
  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 "entry.h"
  33
  34 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  35
  36 /*
  37  * Return saved PC of a blocked thread. used in kernel/sched.
  38  * resume in entry.S does not create a new stack frame, it
  39  * just stores the registers %r6-%r15 to the frame given by
  40  * schedule. We want to return the address of the caller of
  41  * schedule, so we have to walk the backchain one time to
  42  * find the frame schedule() store its return address.
  43  */
  44 unsigned long thread_saved_pc(struct task_struct *tsk)
  45 {
  46         struct stack_frame *sf, *low, *high;
  47
  48         if (!tsk || !task_stack_page(tsk))
  49                 return 0;
  50         low = task_stack_page(tsk);
  51         high = (struct stack_frame *) task_pt_regs(tsk);
  52         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  53         if (sf <= low || sf > high)
  54                 return 0;
  55         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  56         if (sf <= low || sf > high)
  57                 return 0;
  58         return sf->gprs[8];
  59 }
  60
  61 /*
  62  * The idle loop on a S390...
  63  */
  64 static void default_idle(void)
  65 {
  66         if (cpu_is_offline(smp_processor_id()))
  67                 cpu_die();
  68         local_irq_disable();
  69         if (need_resched()) {
  70                 local_irq_enable();
  71                 return;
  72         }
  73         local_mcck_disable();
  74         if (test_thread_flag(TIF_MCCK_PENDING)) {
  75                 local_mcck_enable();
  76                 local_irq_enable();
  77                 s390_handle_mcck();
  78                 return;
  79         }
  80         trace_hardirqs_on();
  81         /* Don't trace preempt off for idle. */
  82         stop_critical_timings();
  83         /* Stop virtual timer and halt the cpu. */
  84         vtime_stop_cpu();
  85         /* Reenable preemption tracer. */
  86         start_critical_timings();
  87 }
  88
  89 void cpu_idle(void)
  90 {
  91         for (;;) {
  92                 tick_nohz_stop_sched_tick(1);
  93                 while (!need_resched())
  94                         default_idle();
  95                 tick_nohz_restart_sched_tick();
  96                 preempt_enable_no_resched();
  97                 schedule();
  98                 preempt_disable();
  99         }
 100 }
 101
 102 extern void __kprobes kernel_thread_starter(void);
 103
 104 asm(
 105         ".section .kprobes.text, \"ax\"\n"
 106         ".global kernel_thread_starter\n"
 107         "kernel_thread_starter:\n"
 108         "    la    2,0(10)\n"
 109         "    basr  14,9\n"
 110         "    la    2,0\n"
 111         "    br    11\n"
 112         ".previous\n");
 113
 114 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 115 {
 116         struct pt_regs regs;
 117
 118         memset(&regs, 0, sizeof(regs));
 119         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 120         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 121         regs.gprs[9] = (unsigned long) fn;
 122         regs.gprs[10] = (unsigned long) arg;
 123         regs.gprs[11] = (unsigned long) do_exit;
 124         regs.orig_gpr2 = -1;
 125
 126         /* Ok, create the new process.. */
 127         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 128                        0, &regs, 0, NULL, NULL);
 129 }
 130 EXPORT_SYMBOL(kernel_thread);
 131
 132 /*
 133  * Free current thread data structures etc..
 134  */
 135 void exit_thread(void)
 136 {
 137 }
 138
 139 void flush_thread(void)
 140 {
 141 }
 142
 143 void release_thread(struct task_struct *dead_task)
 144 {
 145 }
 146
 147 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 148                 unsigned long unused,
 149                 struct task_struct *p, struct pt_regs *regs)
 150 {
 151         struct thread_info *ti;
 152         struct fake_frame
 153         {
 154                 struct stack_frame sf;
 155                 struct pt_regs childregs;
 156         } *frame;
 157
 158         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 159         p->thread.ksp = (unsigned long) frame;
 160         /* Store access registers to kernel stack of new process. */
 161         frame->childregs = *regs;
 162         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 163         frame->childregs.gprs[15] = new_stackp;
 164         frame->sf.back_chain = 0;
 165
 166         /* new return point is ret_from_fork */
 167         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 168
 169         /* fake return stack for resume(), don't go back to schedule */
 170         frame->sf.gprs[9] = (unsigned long) frame;
 171
 172         /* Save access registers to new thread structure. */
 173         save_access_regs(&p->thread.acrs[0]);
 174
 175 #ifndef CONFIG_64BIT
 176         /*
 177          * save fprs to current->thread.fp_regs to merge them with
 178          * the emulated registers and then copy the result to the child.
 179          */
 180         save_fp_regs(&current->thread.fp_regs);
 181         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 182                sizeof(s390_fp_regs));
 183         /* Set a new TLS ?  */
 184         if (clone_flags & CLONE_SETTLS)
 185                 p->thread.acrs[0] = regs->gprs[6];
 186 #else /* CONFIG_64BIT */
 187         /* Save the fpu registers to new thread structure. */
 188         save_fp_regs(&p->thread.fp_regs);
 189         /* Set a new TLS ?  */
 190         if (clone_flags & CLONE_SETTLS) {
 191                 if (is_compat_task()) {
 192                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 193                 } else {
 194                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 195                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 196                 }
 197         }
 198 #endif /* CONFIG_64BIT */
 199         /* start new process with ar4 pointing to the correct address space */
 200         p->thread.mm_segment = get_fs();
 201         /* Don't copy debug registers */
 202         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 203         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 204         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 205         clear_tsk_thread_flag(p, TIF_PER_TRAP);
 206         /* Initialize per thread user and system timer values */
 207         ti = task_thread_info(p);
 208         ti->user_timer = 0;
 209         ti->system_timer = 0;
 210         return 0;
 211 }
 212
 213 SYSCALL_DEFINE0(fork)
 214 {
 215         struct pt_regs *regs = task_pt_regs(current);
 216         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 217 }
 218
 219 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
 220                 int __user *, parent_tidptr, int __user *, child_tidptr)
 221 {
 222         struct pt_regs *regs = task_pt_regs(current);
 223
 224         if (!newsp)
 225                 newsp = regs->gprs[15];
 226         return do_fork(clone_flags, newsp, regs, 0,
 227                        parent_tidptr, child_tidptr);
 228 }
 229
 230 /*
 231  * This is trivial, and on the face of it looks like it
 232  * could equally well be done in user mode.
 233  *
 234  * Not so, for quite unobvious reasons - register pressure.
 235  * In user mode vfork() cannot have a stack frame, and if
 236  * done by calling the "clone()" system call directly, you
 237  * do not have enough call-clobbered registers to hold all
 238  * the information you need.
 239  */
 240 SYSCALL_DEFINE0(vfork)
 241 {
 242         struct pt_regs *regs = task_pt_regs(current);
 243         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 244                        regs->gprs[15], regs, 0, NULL, NULL);
 245 }
 246
 247 asmlinkage void execve_tail(void)
 248 {
 249         current->thread.fp_regs.fpc = 0;
 250         if (MACHINE_HAS_IEEE)
 251                 asm volatile("sfpc %0,%0" : : "d" (0));
 252 }
 253
 254 /*
 255  * sys_execve() executes a new program.
 256  */
 257 SYSCALL_DEFINE3(execve, const char __user *, name,
 258                 const char __user *const __user *, argv,
 259                 const char __user *const __user *, envp)
 260 {
 261         struct pt_regs *regs = task_pt_regs(current);
 262         char *filename;
 263         long rc;
 264
 265         filename = getname(name);
 266         rc = PTR_ERR(filename);
 267         if (IS_ERR(filename))
 268                 return rc;
 269         rc = do_execve(filename, argv, envp, regs);
 270         if (rc)
 271                 goto out;
 272         execve_tail();
 273         rc = regs->gprs[2];
 274 out:
 275         putname(filename);
 276         return rc;
 277 }
 278
 279 /*
 280  * fill in the FPU structure for a core dump.
 281  */
 282 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 283 {
 284 #ifndef CONFIG_64BIT
 285         /*
 286          * save fprs to current->thread.fp_regs to merge them with
 287          * the emulated registers and then copy the result to the dump.
 288          */
 289         save_fp_regs(&current->thread.fp_regs);
 290         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 291 #else /* CONFIG_64BIT */
 292         save_fp_regs(fpregs);
 293 #endif /* CONFIG_64BIT */
 294         return 1;
 295 }
 296 EXPORT_SYMBOL(dump_fpu);
 297
 298 unsigned long get_wchan(struct task_struct *p)
 299 {
 300         struct stack_frame *sf, *low, *high;
 301         unsigned long return_address;
 302         int count;
 303
 304         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 305                 return 0;
 306         low = task_stack_page(p);
 307         high = (struct stack_frame *) task_pt_regs(p);
 308         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 309         if (sf <= low || sf > high)
 310                 return 0;
 311         for (count = 0; count < 16; count++) {
 312                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 313                 if (sf <= low || sf > high)
 314                         return 0;
 315                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 316                 if (!in_sched_functions(return_address))
 317                         return return_address;
 318         }
 319         return 0;
 320 }
 321
 322 unsigned long arch_align_stack(unsigned long sp)
 323 {
 324         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 325                 sp -= get_random_int() & ~PAGE_MASK;
 326         return sp & ~0xf;
 327 }
 328
 329 static inline unsigned long brk_rnd(void)
 330 {
 331         /* 8MB for 32bit, 1GB for 64bit */
 332         if (is_32bit_task())
 333                 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
 334         else
 335                 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
 336 }
 337
 338 unsigned long arch_randomize_brk(struct mm_struct *mm)
 339 {
 340         unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
 341
 342         if (ret < mm->brk)
 343                 return mm->brk;
 344         return ret;
 345 }
 346
 347 unsigned long randomize_et_dyn(unsigned long base)
 348 {
 349         unsigned long ret = PAGE_ALIGN(base + brk_rnd());
 350
 351         if (!(current->flags & PF_RANDOMIZE))
 352                 return base;
 353         if (ret < base)
 354                 return base;
 355         return ret;
 356 }