arch/avr32/kernel/process.c

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #include <linux/sched.h>
   9 #include <linux/module.h>
  10 #include <linux/kallsyms.h>
  11 #include <linux/fs.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/reboot.h>
  14 #include <linux/unistd.h>
  15
  16 #include <asm/sysreg.h>
  17 #include <asm/ocd.h>
  18
  19 void (*pm_power_off)(void) = NULL;
  20 EXPORT_SYMBOL(pm_power_off);
  21
  22 /*
  23  * This file handles the architecture-dependent parts of process handling..
  24  */
  25
  26 void cpu_idle(void)
  27 {
  28         /* endless idle loop with no priority at all */
  29         while (1) {
  30                 /* TODO: Enter sleep mode */
  31                 while (!need_resched())
  32                         cpu_relax();
  33                 preempt_enable_no_resched();
  34                 schedule();
  35                 preempt_disable();
  36         }
  37 }
  38
  39 void machine_halt(void)
  40 {
  41         /*
  42          * Enter Stop mode. The 32 kHz oscillator will keep running so
  43          * the RTC will keep the time properly and the system will
  44          * boot quickly.
  45          */
  46         asm volatile("sleep 3\n\t"
  47                      "sub pc, -2");
  48 }
  49
  50 void machine_power_off(void)
  51 {
  52 }
  53
  54 void machine_restart(char *cmd)
  55 {
  56         __mtdr(DBGREG_DC, DC_DBE);
  57         __mtdr(DBGREG_DC, DC_RES);
  58         while (1) ;
  59 }
  60
  61 /*
  62  * PC is actually discarded when returning from a system call -- the
  63  * return address must be stored in LR. This function will make sure
  64  * LR points to do_exit before starting the thread.
  65  *
  66  * Also, when returning from fork(), r12 is 0, so we must copy the
  67  * argument as well.
  68  *
  69  *  r0 : The argument to the main thread function
  70  *  r1 : The address of do_exit
  71  *  r2 : The address of the main thread function
  72  */
  73 asmlinkage extern void kernel_thread_helper(void);
  74 __asm__("       .type   kernel_thread_helper, @function\n"
  75         "kernel_thread_helper:\n"
  76         "       mov     r12, r0\n"
  77         "       mov     lr, r2\n"
  78         "       mov     pc, r1\n"
  79         "       .size   kernel_thread_helper, . - kernel_thread_helper");
  80
  81 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
  82 {
  83         struct pt_regs regs;
  84
  85         memset(&regs, 0, sizeof(regs));
  86
  87         regs.r0 = (unsigned long)arg;
  88         regs.r1 = (unsigned long)fn;
  89         regs.r2 = (unsigned long)do_exit;
  90         regs.lr = (unsigned long)kernel_thread_helper;
  91         regs.pc = (unsigned long)kernel_thread_helper;
  92         regs.sr = MODE_SUPERVISOR;
  93
  94         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
  95                        0, &regs, 0, NULL, NULL);
  96 }
  97 EXPORT_SYMBOL(kernel_thread);
  98
  99 /*
 100  * Free current thread data structures etc
 101  */
 102 void exit_thread(void)
 103 {
 104         /* nothing to do */
 105 }
 106
 107 void flush_thread(void)
 108 {
 109         /* nothing to do */
 110 }
 111
 112 void release_thread(struct task_struct *dead_task)
 113 {
 114         /* do nothing */
 115 }
 116
 117 static const char *cpu_modes[] = {
 118         "Application", "Supervisor", "Interrupt level 0", "Interrupt level 1",
 119         "Interrupt level 2", "Interrupt level 3", "Exception", "NMI"
 120 };
 121
 122 void show_regs(struct pt_regs *regs)
 123 {
 124         unsigned long sp = regs->sp;
 125         unsigned long lr = regs->lr;
 126         unsigned long mode = (regs->sr & MODE_MASK) >> MODE_SHIFT;
 127
 128         if (!user_mode(regs))
 129                 sp = (unsigned long)regs + FRAME_SIZE_FULL;
 130
 131         print_symbol("PC is at %s\n", instruction_pointer(regs));
 132         print_symbol("LR is at %s\n", lr);
 133         printk("pc : [<%08lx>]    lr : [<%08lx>]    %s\n"
 134                "sp : %08lx  r12: %08lx  r11: %08lx\n",
 135                instruction_pointer(regs),
 136                lr, print_tainted(), sp, regs->r12, regs->r11);
 137         printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
 138                regs->r10, regs->r9, regs->r8);
 139         printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
 140                regs->r7, regs->r6, regs->r5, regs->r4);
 141         printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
 142                regs->r3, regs->r2, regs->r1, regs->r0);
 143         printk("Flags: %c%c%c%c%c\n",
 144                regs->sr & SR_Q ? 'Q' : 'q',
 145                regs->sr & SR_V ? 'V' : 'v',
 146                regs->sr & SR_N ? 'N' : 'n',
 147                regs->sr & SR_Z ? 'Z' : 'z',
 148                regs->sr & SR_C ? 'C' : 'c');
 149         printk("Mode bits: %c%c%c%c%c%c%c%c%c\n",
 150                regs->sr & SR_H ? 'H' : 'h',
 151                regs->sr & SR_R ? 'R' : 'r',
 152                regs->sr & SR_J ? 'J' : 'j',
 153                regs->sr & SR_EM ? 'E' : 'e',
 154                regs->sr & SR_I3M ? '3' : '.',
 155                regs->sr & SR_I2M ? '2' : '.',
 156                regs->sr & SR_I1M ? '1' : '.',
 157                regs->sr & SR_I0M ? '0' : '.',
 158                regs->sr & SR_GM ? 'G' : 'g');
 159         printk("CPU Mode: %s\n", cpu_modes[mode]);
 160
 161         show_trace(NULL, (unsigned long *)sp, regs);
 162 }
 163 EXPORT_SYMBOL(show_regs);
 164
 165 /* Fill in the fpu structure for a core dump. This is easy -- we don't have any */
 166 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 167 {
 168         /* Not valid */
 169         return 0;
 170 }
 171
 172 asmlinkage void ret_from_fork(void);
 173
 174 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 175                 unsigned long unused,
 176                 struct task_struct *p, struct pt_regs *regs)
 177 {
 178         struct pt_regs *childregs;
 179
 180         childregs = ((struct pt_regs *)(THREAD_SIZE + (unsigned long)p->thread_info)) - 1;
 181         *childregs = *regs;
 182
 183         if (user_mode(regs))
 184                 childregs->sp = usp;
 185         else
 186                 childregs->sp = (unsigned long)p->thread_info + THREAD_SIZE;
 187
 188         childregs->r12 = 0; /* Set return value for child */
 189
 190         p->thread.cpu_context.sr = MODE_SUPERVISOR | SR_GM;
 191         p->thread.cpu_context.ksp = (unsigned long)childregs;
 192         p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
 193
 194         return 0;
 195 }
 196
 197 /* r12-r8 are dummy parameters to force the compiler to use the stack */
 198 asmlinkage int sys_fork(struct pt_regs *regs)
 199 {
 200         return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
 201 }
 202
 203 asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
 204                          unsigned long parent_tidptr,
 205                          unsigned long child_tidptr, struct pt_regs *regs)
 206 {
 207         if (!newsp)
 208                 newsp = regs->sp;
 209         return do_fork(clone_flags, newsp, regs, 0,
 210                        (int __user *)parent_tidptr,
 211                        (int __user *)child_tidptr);
 212 }
 213
 214 asmlinkage int sys_vfork(struct pt_regs *regs)
 215 {
 216         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs,
 217                        0, NULL, NULL);
 218 }
 219
 220 asmlinkage int sys_execve(char __user *ufilename, char __user *__user *uargv,
 221                           char __user *__user *uenvp, struct pt_regs *regs)
 222 {
 223         int error;
 224         char *filename;
 225
 226         filename = getname(ufilename);
 227         error = PTR_ERR(filename);
 228         if (IS_ERR(filename))
 229                 goto out;
 230
 231         error = do_execve(filename, uargv, uenvp, regs);
 232         if (error == 0)
 233                 current->ptrace &= ~PT_DTRACE;
 234         putname(filename);
 235
 236 out:
 237         return error;
 238 }
 239
 240
 241 /*
 242  * This function is supposed to answer the question "who called
 243  * schedule()?"
 244  */
 245 unsigned long get_wchan(struct task_struct *p)
 246 {
 247         unsigned long pc;
 248         unsigned long stack_page;
 249
 250         if (!p || p == current || p->state == TASK_RUNNING)
 251                 return 0;
 252
 253         stack_page = (unsigned long)p->thread_info;
 254         BUG_ON(!stack_page);
 255
 256         /*
 257          * The stored value of PC is either the address right after
 258          * the call to __switch_to() or ret_from_fork.
 259          */
 260         pc = thread_saved_pc(p);
 261         if (in_sched_functions(pc)) {
 262 #ifdef CONFIG_FRAME_POINTER
 263                 unsigned long fp = p->thread.cpu_context.r7;
 264                 BUG_ON(fp < stack_page || fp > (THREAD_SIZE + stack_page));
 265                 pc = *(unsigned long *)fp;
 266 #else
 267                 /*
 268                  * We depend on the frame size of schedule here, which
 269                  * is actually quite ugly. It might be possible to
 270                  * determine the frame size automatically at build
 271                  * time by doing this:
 272                  *   - compile sched.c
 273                  *   - disassemble the resulting sched.o
 274                  *   - look for 'sub sp,??' shortly after '<schedule>:'
 275                  */
 276                 unsigned long sp = p->thread.cpu_context.ksp + 16;
 277                 BUG_ON(sp < stack_page || sp > (THREAD_SIZE + stack_page));
 278                 pc = *(unsigned long *)sp;
 279 #endif
 280         }
 281
 282         return pc;
 283 }