arch/openrisc/kernel/process.c

   1 /*
   2  * OpenRISC process.c
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * Modifications for the OpenRISC architecture:
   9  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  10  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  *
  17  * This file handles the architecture-dependent parts of process handling...
  18  */
  19
  20 #define __KERNEL_SYSCALLS__
  21 #include <stdarg.h>
  22
  23 #include <linux/errno.h>
  24 #include <linux/sched.h>
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/mm.h>
  28 #include <linux/stddef.h>
  29 #include <linux/unistd.h>
  30 #include <linux/ptrace.h>
  31 #include <linux/slab.h>
  32 #include <linux/elfcore.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/delay.h>
  35 #include <linux/init_task.h>
  36 #include <linux/mqueue.h>
  37 #include <linux/fs.h>
  38
  39 #include <asm/uaccess.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/io.h>
  42 #include <asm/processor.h>
  43 #include <asm/spr_defs.h>
  44
  45 #include <linux/smp.h>
  46
  47 /*
  48  * Pointer to Current thread info structure.
  49  *
  50  * Used at user space -> kernel transitions.
  51  */
  52 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
  53
  54 void machine_restart(void)
  55 {
  56         printk(KERN_INFO "*** MACHINE RESTART ***\n");
  57         __asm__("l.nop 1");
  58 }
  59
  60 /*
  61  * Similar to machine_power_off, but don't shut off power.  Add code
  62  * here to freeze the system for e.g. post-mortem debug purpose when
  63  * possible.  This halt has nothing to do with the idle halt.
  64  */
  65 void machine_halt(void)
  66 {
  67         printk(KERN_INFO "*** MACHINE HALT ***\n");
  68         __asm__("l.nop 1");
  69 }
  70
  71 /* If or when software power-off is implemented, add code here.  */
  72 void machine_power_off(void)
  73 {
  74         printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
  75         __asm__("l.nop 1");
  76 }
  77
  78 void (*pm_power_off) (void) = machine_power_off;
  79
  80 /*
  81  * When a process does an "exec", machine state like FPU and debug
  82  * registers need to be reset.  This is a hook function for that.
  83  * Currently we don't have any such state to reset, so this is empty.
  84  */
  85 void flush_thread(void)
  86 {
  87 }
  88
  89 void show_regs(struct pt_regs *regs)
  90 {
  91         extern void show_registers(struct pt_regs *regs);
  92
  93         /* __PHX__ cleanup this mess */
  94         show_registers(regs);
  95 }
  96
  97 unsigned long thread_saved_pc(struct task_struct *t)
  98 {
  99         return (unsigned long)user_regs(t->stack)->pc;
 100 }
 101
 102 void release_thread(struct task_struct *dead_task)
 103 {
 104 }
 105
 106 /*
 107  * Copy the thread-specific (arch specific) info from the current
 108  * process to the new one p
 109  */
 110 extern asmlinkage void ret_from_fork(void);
 111
 112 /*
 113  * copy_thread
 114  * @clone_flags: flags
 115  * @usp: user stack pointer or fn for kernel thread
 116  * @arg: arg to fn for kernel thread; always NULL for userspace thread
 117  * @p: the newly created task
 118  * @regs: CPU context to copy for userspace thread; always NULL for kthread
 119  *
 120  * At the top of a newly initialized kernel stack are two stacked pt_reg
 121  * structures.  The first (topmost) is the userspace context of the thread.
 122  * The second is the kernelspace context of the thread.
 123  *
 124  * A kernel thread will not be returning to userspace, so the topmost pt_regs
 125  * struct can be uninitialized; it _does_ need to exist, though, because
 126  * a kernel thread can become a userspace thread by doing a kernel_execve, in
 127  * which case the topmost context will be initialized and used for 'returning'
 128  * to userspace.
 129  *
 130  * The second pt_reg struct needs to be initialized to 'return' to
 131  * ret_from_fork.  A kernel thread will need to set r20 to the address of
 132  * a function to call into (with arg in r22); userspace threads need to set
 133  * r20 to NULL in which case ret_from_fork will just continue a return to
 134  * userspace.
 135  *
 136  * A kernel thread 'fn' may return; this is effectively what happens when
 137  * kernel_execve is called.  In that case, the userspace pt_regs must have
 138  * been initialized (which kernel_execve takes care of, see start_thread
 139  * below); ret_from_fork will then continue its execution causing the
 140  * 'kernel thread' to return to userspace as a userspace thread.
 141  */
 142
 143 int
 144 copy_thread(unsigned long clone_flags, unsigned long usp,
 145             unsigned long arg, struct task_struct *p)
 146 {
 147         struct pt_regs *userregs;
 148         struct pt_regs *kregs;
 149         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 150         unsigned long top_of_kernel_stack;
 151
 152         top_of_kernel_stack = sp;
 153
 154         p->set_child_tid = p->clear_child_tid = NULL;
 155
 156         /* Locate userspace context on stack... */
 157         sp -= STACK_FRAME_OVERHEAD;     /* redzone */
 158         sp -= sizeof(struct pt_regs);
 159         userregs = (struct pt_regs *) sp;
 160
 161         /* ...and kernel context */
 162         sp -= STACK_FRAME_OVERHEAD;     /* redzone */
 163         sp -= sizeof(struct pt_regs);
 164         kregs = (struct pt_regs *)sp;
 165
 166         if (unlikely(p->flags & PF_KTHREAD)) {
 167                 memset(kregs, 0, sizeof(struct pt_regs));
 168                 kregs->gpr[20] = usp; /* fn, kernel thread */
 169                 kregs->gpr[22] = arg;
 170         } else {
 171                 *userregs = *current_pt_regs();
 172
 173                 if (usp)
 174                         userregs->sp = usp;
 175                 userregs->gpr[11] = 0;  /* Result from fork() */
 176
 177                 kregs->gpr[20] = 0;     /* Userspace thread */
 178         }
 179
 180         /*
 181          * _switch wants the kernel stack page in pt_regs->sp so that it
 182          * can restore it to thread_info->ksp... see _switch for details.
 183          */
 184         kregs->sp = top_of_kernel_stack;
 185         kregs->gpr[9] = (unsigned long)ret_from_fork;
 186
 187         task_thread_info(p)->ksp = (unsigned long)kregs;
 188
 189         return 0;
 190 }
 191
 192 /*
 193  * Set up a thread for executing a new program
 194  */
 195 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 196 {
 197         unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
 198
 199         set_fs(USER_DS);
 200         memset(regs, 0, sizeof(struct pt_regs));
 201
 202         regs->pc = pc;
 203         regs->sr = sr;
 204         regs->sp = sp;
 205 }
 206
 207 /* Fill in the fpu structure for a core dump.  */
 208 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
 209 {
 210         /* TODO */
 211         return 0;
 212 }
 213
 214 extern struct thread_info *_switch(struct thread_info *old_ti,
 215                                    struct thread_info *new_ti);
 216
 217 struct task_struct *__switch_to(struct task_struct *old,
 218                                 struct task_struct *new)
 219 {
 220         struct task_struct *last;
 221         struct thread_info *new_ti, *old_ti;
 222         unsigned long flags;
 223
 224         local_irq_save(flags);
 225
 226         /* current_set is an array of saved current pointers
 227          * (one for each cpu). we need them at user->kernel transition,
 228          * while we save them at kernel->user transition
 229          */
 230         new_ti = new->stack;
 231         old_ti = old->stack;
 232
 233         current_thread_info_set[smp_processor_id()] = new_ti;
 234         last = (_switch(old_ti, new_ti))->task;
 235
 236         local_irq_restore(flags);
 237
 238         return last;
 239 }
 240
 241 /*
 242  * Write out registers in core dump format, as defined by the
 243  * struct user_regs_struct
 244  */
 245 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
 246 {
 247         dest[0] = 0; /* r0 */
 248         memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
 249         dest[32] = regs->pc;
 250         dest[33] = regs->sr;
 251         dest[34] = 0;
 252         dest[35] = 0;
 253 }
 254
 255 unsigned long get_wchan(struct task_struct *p)
 256 {
 257         /* TODO */
 258
 259         return 0;
 260 }