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/system.h>
  42 #include <asm/io.h>
  43 #include <asm/processor.h>
  44 #include <asm/spr_defs.h>
  45
  46 #include <linux/smp.h>
  47
  48 /*
  49  * Pointer to Current thread info structure.
  50  *
  51  * Used at user space -> kernel transitions.
  52  */
  53 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
  54
  55 void machine_restart(void)
  56 {
  57         printk(KERN_INFO "*** MACHINE RESTART ***\n");
  58         __asm__("l.nop 1");
  59 }
  60
  61 /*
  62  * Similar to machine_power_off, but don't shut off power.  Add code
  63  * here to freeze the system for e.g. post-mortem debug purpose when
  64  * possible.  This halt has nothing to do with the idle halt.
  65  */
  66 void machine_halt(void)
  67 {
  68         printk(KERN_INFO "*** MACHINE HALT ***\n");
  69         __asm__("l.nop 1");
  70 }
  71
  72 /* If or when software power-off is implemented, add code here.  */
  73 void machine_power_off(void)
  74 {
  75         printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
  76         __asm__("l.nop 1");
  77 }
  78
  79 void (*pm_power_off) (void) = machine_power_off;
  80
  81 /*
  82  * When a process does an "exec", machine state like FPU and debug
  83  * registers need to be reset.  This is a hook function for that.
  84  * Currently we don't have any such state to reset, so this is empty.
  85  */
  86 void flush_thread(void)
  87 {
  88 }
  89
  90 void show_regs(struct pt_regs *regs)
  91 {
  92         extern void show_registers(struct pt_regs *regs);
  93
  94         /* __PHX__ cleanup this mess */
  95         show_registers(regs);
  96 }
  97
  98 unsigned long thread_saved_pc(struct task_struct *t)
  99 {
 100         return (unsigned long)user_regs(t->stack)->pc;
 101 }
 102
 103 void release_thread(struct task_struct *dead_task)
 104 {
 105 }
 106
 107 /*
 108  * Copy the thread-specific (arch specific) info from the current
 109  * process to the new one p
 110  */
 111 extern asmlinkage void ret_from_fork(void);
 112
 113 int
 114 copy_thread(unsigned long clone_flags, unsigned long usp,
 115             unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 116 {
 117         struct pt_regs *childregs;
 118         struct pt_regs *kregs;
 119         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 120         struct thread_info *ti;
 121         unsigned long top_of_kernel_stack;
 122
 123         top_of_kernel_stack = sp;
 124
 125         p->set_child_tid = p->clear_child_tid = NULL;
 126
 127         /* Copy registers */
 128         /* redzone */
 129         sp -= STACK_FRAME_OVERHEAD;
 130         sp -= sizeof(struct pt_regs);
 131         childregs = (struct pt_regs *)sp;
 132
 133         /* Copy parent registers */
 134         *childregs = *regs;
 135
 136         if ((childregs->sr & SPR_SR_SM) == 1) {
 137                 /* for kernel thread, set `current_thread_info'
 138                  * and stackptr in new task
 139                  */
 140                 childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 141                 childregs->gpr[10] = (unsigned long)task_thread_info(p);
 142         } else {
 143                 childregs->sp = usp;
 144         }
 145
 146         childregs->gpr[11] = 0; /* Result from fork() */
 147
 148         /*
 149          * The way this works is that at some point in the future
 150          * some task will call _switch to switch to the new task.
 151          * That will pop off the stack frame created below and start
 152          * the new task running at ret_from_fork.  The new task will
 153          * do some house keeping and then return from the fork or clone
 154          * system call, using the stack frame created above.
 155          */
 156         /* redzone */
 157         sp -= STACK_FRAME_OVERHEAD;
 158         sp -= sizeof(struct pt_regs);
 159         kregs = (struct pt_regs *)sp;
 160
 161         ti = task_thread_info(p);
 162         ti->ksp = sp;
 163
 164         /* kregs->sp must store the location of the 'pre-switch' kernel stack
 165          * pointer... for a newly forked process, this is simply the top of
 166          * the kernel stack.
 167          */
 168         kregs->sp = top_of_kernel_stack;
 169         kregs->gpr[3] = (unsigned long)current; /* arg to schedule_tail */
 170         kregs->gpr[10] = (unsigned long)task_thread_info(p);
 171         kregs->gpr[9] = (unsigned long)ret_from_fork;
 172
 173         return 0;
 174 }
 175
 176 /*
 177  * Set up a thread for executing a new program
 178  */
 179 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 180 {
 181         unsigned long sr = regs->sr & ~SPR_SR_SM;
 182
 183         set_fs(USER_DS);
 184         memset(regs->gpr, 0, sizeof(regs->gpr));
 185
 186         regs->pc = pc;
 187         regs->sr = sr;
 188         regs->sp = sp;
 189
 190 /*      printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/
 191 }
 192
 193 /* Fill in the fpu structure for a core dump.  */
 194 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
 195 {
 196         /* TODO */
 197         return 0;
 198 }
 199
 200 extern struct thread_info *_switch(struct thread_info *old_ti,
 201                                    struct thread_info *new_ti);
 202
 203 struct task_struct *__switch_to(struct task_struct *old,
 204                                 struct task_struct *new)
 205 {
 206         struct task_struct *last;
 207         struct thread_info *new_ti, *old_ti;
 208         unsigned long flags;
 209
 210         local_irq_save(flags);
 211
 212         /* current_set is an array of saved current pointers
 213          * (one for each cpu). we need them at user->kernel transition,
 214          * while we save them at kernel->user transition
 215          */
 216         new_ti = new->stack;
 217         old_ti = old->stack;
 218
 219         current_thread_info_set[smp_processor_id()] = new_ti;
 220         last = (_switch(old_ti, new_ti))->task;
 221
 222         local_irq_restore(flags);
 223
 224         return last;
 225 }
 226
 227 /*
 228  * Write out registers in core dump format, as defined by the
 229  * struct user_regs_struct
 230  */
 231 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
 232 {
 233         dest[0] = 0; /* r0 */
 234         memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
 235         dest[32] = regs->pc;
 236         dest[33] = regs->sr;
 237         dest[34] = 0;
 238         dest[35] = 0;
 239 }
 240
 241 extern void _kernel_thread_helper(void);
 242
 243 void __noreturn kernel_thread_helper(int (*fn) (void *), void *arg)
 244 {
 245         do_exit(fn(arg));
 246 }
 247
 248 /*
 249  * Create a kernel thread.
 250  */
 251 int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
 252 {
 253         struct pt_regs regs;
 254
 255         memset(&regs, 0, sizeof(regs));
 256
 257         regs.gpr[20] = (unsigned long)fn;
 258         regs.gpr[22] = (unsigned long)arg;
 259         regs.sr = mfspr(SPR_SR);
 260         regs.pc = (unsigned long)_kernel_thread_helper;
 261
 262         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 263                        0, &regs, 0, NULL, NULL);
 264 }
 265
 266 /*
 267  * sys_execve() executes a new program.
 268  */
 269 asmlinkage long _sys_execve(const char __user *name,
 270                             const char __user * const __user *argv,
 271                             const char __user * const __user *envp,
 272                             struct pt_regs *regs)
 273 {
 274         int error;
 275         char *filename;
 276
 277         filename = getname(name);
 278         error = PTR_ERR(filename);
 279
 280         if (IS_ERR(filename))
 281                 goto out;
 282
 283         error = do_execve(filename, argv, envp, regs);
 284         putname(filename);
 285
 286 out:
 287         return error;
 288 }
 289
 290 unsigned long get_wchan(struct task_struct *p)
 291 {
 292         /* TODO */
 293
 294         return 0;
 295 }
 296
 297 int kernel_execve(const char *filename, char *const argv[], char *const envp[])
 298 {
 299         register long __res asm("r11") = __NR_execve;
 300         register long __a asm("r3") = (long)(filename);
 301         register long __b asm("r4") = (long)(argv);
 302         register long __c asm("r5") = (long)(envp);
 303         __asm__ volatile ("l.sys 1"
 304                           : "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)
 305                           : "0"(__res), "1"(__a), "2"(__b), "3"(__c)
 306                           : "r6", "r7", "r8", "r12", "r13", "r15",
 307                             "r17", "r19", "r21", "r23", "r25", "r27",
 308                             "r29", "r31");
 309         __asm__ volatile ("l.nop");
 310         return __res;
 311 }