release/src-rt-6.x.4708/linux/linux-2.6.36/arch/cris/arch-v10/kernel/process.c

   1 /*
   2  *  linux/arch/cris/kernel/process.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  *  Copyright (C) 2000-2002  Axis Communications AB
   6  *
   7  *  Authors:   Bjorn Wesen (bjornw@axis.com)
   8  *             Mikael Starvik (starvik@axis.com)
   9  *
  10  * This file handles the architecture-dependent parts of process handling..
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/err.h>
  16 #include <linux/fs.h>
  17 #include <arch/svinto.h>
  18 #include <linux/init.h>
  19
  20 #ifdef CONFIG_ETRAX_GPIO
  21 void etrax_gpio_wake_up_check(void); /* drivers/gpio.c */
  22 #endif
  23
  24 /*
  25  * We use this if we don't have any better
  26  * idle routine..
  27  */
  28 void default_idle(void)
  29 {
  30 #ifdef CONFIG_ETRAX_GPIO
  31   etrax_gpio_wake_up_check();
  32 #endif
  33 }
  34
  35 /*
  36  * Free current thread data structures etc..
  37  */
  38
  39 void exit_thread(void)
  40 {
  41         /* Nothing needs to be done.  */
  42 }
  43
  44 /* if the watchdog is enabled, we can simply disable interrupts and go
  45  * into an eternal loop, and the watchdog will reset the CPU after 0.1s
  46  * if on the other hand the watchdog wasn't enabled, we just enable it and wait
  47  */
  48
  49 void hard_reset_now (void)
  50 {
  51         /*
  52          * Don't declare this variable elsewhere.  We don't want any other
  53          * code to know about it than the watchdog handler in entry.S and
  54          * this code, implementing hard reset through the watchdog.
  55          */
  56 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
  57         extern int cause_of_death;
  58 #endif
  59
  60         printk("*** HARD RESET ***\n");
  61         local_irq_disable();
  62
  63 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
  64         cause_of_death = 0xbedead;
  65 #else
  66         /* Since we dont plan to keep on resetting the watchdog,
  67            the key can be arbitrary hence three */
  68         *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, 3) |
  69                 IO_STATE(R_WATCHDOG, enable, start);
  70 #endif
  71
  72         while(1) /* waiting for RETRIBUTION! */ ;
  73 }
  74
  75 /*
  76  * Return saved PC of a blocked thread.
  77  */
  78 unsigned long thread_saved_pc(struct task_struct *t)
  79 {
  80         return task_pt_regs(t)->irp;
  81 }
  82
  83 static void kernel_thread_helper(void* dummy, int (*fn)(void *), void * arg)
  84 {
  85   fn(arg);
  86   do_exit(-1); /* Should never be called, return bad exit value */
  87 }
  88
  89 /*
  90  * Create a kernel thread
  91  */
  92 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  93 {
  94         struct pt_regs regs;
  95
  96         memset(&regs, 0, sizeof(regs));
  97
  98         /* Don't use r10 since that is set to 0 in copy_thread */
  99         regs.r11 = (unsigned long)fn;
 100         regs.r12 = (unsigned long)arg;
 101         regs.irp = (unsigned long)kernel_thread_helper;
 102         regs.dccr = 1 << I_DCCR_BITNR;
 103
 104         /* Ok, create the new process.. */
 105         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 106 }
 107
 108 /* setup the child's kernel stack with a pt_regs and switch_stack on it.
 109  * it will be un-nested during _resume and _ret_from_sys_call when the
 110  * new thread is scheduled.
 111  *
 112  * also setup the thread switching structure which is used to keep
 113  * thread-specific data during _resumes.
 114  *
 115  */
 116 asmlinkage void ret_from_fork(void);
 117
 118 int copy_thread(unsigned long clone_flags, unsigned long usp,
 119                 unsigned long unused,
 120                 struct task_struct *p, struct pt_regs *regs)
 121 {
 122         struct pt_regs * childregs;
 123         struct switch_stack *swstack;
 124
 125         /* put the pt_regs structure at the end of the new kernel stack page and fix it up
 126          * remember that the task_struct doubles as the kernel stack for the task
 127          */
 128
 129         childregs = task_pt_regs(p);
 130
 131         *childregs = *regs;  /* struct copy of pt_regs */
 132
 133         p->set_child_tid = p->clear_child_tid = NULL;
 134
 135         childregs->r10 = 0;  /* child returns 0 after a fork/clone */
 136
 137         /* put the switch stack right below the pt_regs */
 138
 139         swstack = ((struct switch_stack *)childregs) - 1;
 140
 141         swstack->r9 = 0; /* parameter to ret_from_sys_call, 0 == dont restart the syscall */
 142
 143         /* we want to return into ret_from_sys_call after the _resume */
 144
 145         swstack->return_ip = (unsigned long) ret_from_fork; /* Will call ret_from_sys_call */
 146
 147         /* fix the user-mode stackpointer */
 148
 149         p->thread.usp = usp;
 150
 151         /* and the kernel-mode one */
 152
 153         p->thread.ksp = (unsigned long) swstack;
 154
 155 #ifdef DEBUG
 156         printk("copy_thread: new regs at 0x%p, as shown below:\n", childregs);
 157         show_registers(childregs);
 158 #endif
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * Be aware of the "magic" 7th argument in the four system-calls below.
 165  * They need the latest stackframe, which is put as the 7th argument by
 166  * entry.S. The previous arguments are dummies or actually used, but need
 167  * to be defined to reach the 7th argument.
 168  *
 169  * N.B.: Another method to get the stackframe is to use current_regs(). But
 170  * it returns the latest stack-frame stacked when going from _user mode_ and
 171  * some of these (at least sys_clone) are called from kernel-mode sometimes
 172  * (for example during kernel_thread, above) and thus cannot use it. Thus,
 173  * to be sure not to get any surprises, we use the method for the other calls
 174  * as well.
 175  */
 176
 177 asmlinkage int sys_fork(long r10, long r11, long r12, long r13, long mof, long srp,
 178                         struct pt_regs *regs)
 179 {
 180         return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
 181 }
 182
 183 /* if newusp is 0, we just grab the old usp */
 184 asmlinkage int sys_clone(unsigned long newusp, unsigned long flags,
 185                          int* parent_tid, int* child_tid, long mof, long srp,
 186                          struct pt_regs *regs)
 187 {
 188         if (!newusp)
 189                 newusp = rdusp();
 190         return do_fork(flags, newusp, regs, 0, parent_tid, child_tid);
 191 }
 192
 193 /* vfork is a system call in i386 because of register-pressure - maybe
 194  * we can remove it and handle it in libc but we put it here until then.
 195  */
 196
 197 asmlinkage int sys_vfork(long r10, long r11, long r12, long r13, long mof, long srp,
 198                          struct pt_regs *regs)
 199 {
 200         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL, NULL);
 201 }
 202
 203 /*
 204  * sys_execve() executes a new program.
 205  */
 206 asmlinkage int sys_execve(const char *fname,
 207                           const char *const *argv,
 208                           const char *const *envp,
 209                           long r13, long mof, long srp,
 210                           struct pt_regs *regs)
 211 {
 212         int error;
 213         char *filename;
 214
 215         filename = getname(fname);
 216         error = PTR_ERR(filename);
 217
 218         if (IS_ERR(filename))
 219                 goto out;
 220         error = do_execve(filename, argv, envp, regs);
 221         putname(filename);
 222  out:
 223         return error;
 224 }
 225
 226 unsigned long get_wchan(struct task_struct *p)
 227 {
 228         return 0;
 229 }
 230 #undef last_sched
 231 #undef first_sched
 232
 233 void show_regs(struct pt_regs * regs)
 234 {
 235         unsigned long usp = rdusp();
 236         printk("IRP: %08lx SRP: %08lx DCCR: %08lx USP: %08lx MOF: %08lx\n",
 237                regs->irp, regs->srp, regs->dccr, usp, regs->mof );
 238         printk(" r0: %08lx  r1: %08lx   r2: %08lx  r3: %08lx\n",
 239                regs->r0, regs->r1, regs->r2, regs->r3);
 240         printk(" r4: %08lx  r5: %08lx   r6: %08lx  r7: %08lx\n",
 241                regs->r4, regs->r5, regs->r6, regs->r7);
 242         printk(" r8: %08lx  r9: %08lx  r10: %08lx r11: %08lx\n",
 243                regs->r8, regs->r9, regs->r10, regs->r11);
 244         printk("r12: %08lx r13: %08lx oR10: %08lx\n",
 245                regs->r12, regs->r13, regs->orig_r10);
 246 }