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 int
 113 copy_thread(unsigned long clone_flags, unsigned long usp,
 114             unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 115 {
 116         struct pt_regs *childregs;
 117         struct pt_regs *kregs;
 118         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 119         struct thread_info *ti;
 120         unsigned long top_of_kernel_stack;
 121
 122         top_of_kernel_stack = sp;
 123
 124         p->set_child_tid = p->clear_child_tid = NULL;
 125
 126         /* Copy registers */
 127         /* redzone */
 128         sp -= STACK_FRAME_OVERHEAD;
 129         sp -= sizeof(struct pt_regs);
 130         childregs = (struct pt_regs *)sp;
 131
 132         /* Copy parent registers */
 133         *childregs = *regs;
 134
 135         if ((childregs->sr & SPR_SR_SM) == 1) {
 136                 /* for kernel thread, set `current_thread_info'
 137                  * and stackptr in new task
 138                  */
 139                 childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 140                 childregs->gpr[10] = (unsigned long)task_thread_info(p);
 141         } else {
 142                 childregs->sp = usp;
 143         }
 144
 145         childregs->gpr[11] = 0; /* Result from fork() */
 146
 147         /*
 148          * The way this works is that at some point in the future
 149          * some task will call _switch to switch to the new task.
 150          * That will pop off the stack frame created below and start
 151          * the new task running at ret_from_fork.  The new task will
 152          * do some house keeping and then return from the fork or clone
 153          * system call, using the stack frame created above.
 154          */
 155         /* redzone */
 156         sp -= STACK_FRAME_OVERHEAD;
 157         sp -= sizeof(struct pt_regs);
 158         kregs = (struct pt_regs *)sp;
 159
 160         ti = task_thread_info(p);
 161         ti->ksp = sp;
 162
 163         /* kregs->sp must store the location of the 'pre-switch' kernel stack
 164          * pointer... for a newly forked process, this is simply the top of
 165          * the kernel stack.
 166          */
 167         kregs->sp = top_of_kernel_stack;
 168         kregs->gpr[3] = (unsigned long)current; /* arg to schedule_tail */
 169         kregs->gpr[10] = (unsigned long)task_thread_info(p);
 170         kregs->gpr[9] = (unsigned long)ret_from_fork;
 171
 172         return 0;
 173 }
 174
 175 /*
 176  * Set up a thread for executing a new program
 177  */
 178 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 179 {
 180         unsigned long sr = regs->sr & ~SPR_SR_SM;
 181
 182         set_fs(USER_DS);
 183         memset(regs->gpr, 0, sizeof(regs->gpr));
 184
 185         regs->pc = pc;
 186         regs->sr = sr;
 187         regs->sp = sp;
 188
 189 /*      printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/
 190 }
 191
 192 /* Fill in the fpu structure for a core dump.  */
 193 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
 194 {
 195         /* TODO */
 196         return 0;
 197 }
 198
 199 extern struct thread_info *_switch(struct thread_info *old_ti,
 200                                    struct thread_info *new_ti);
 201
 202 struct task_struct *__switch_to(struct task_struct *old,
 203                                 struct task_struct *new)
 204 {
 205         struct task_struct *last;
 206         struct thread_info *new_ti, *old_ti;
 207         unsigned long flags;
 208
 209         local_irq_save(flags);
 210
 211         /* current_set is an array of saved current pointers
 212          * (one for each cpu). we need them at user->kernel transition,
 213          * while we save them at kernel->user transition
 214          */
 215         new_ti = new->stack;
 216         old_ti = old->stack;
 217
 218         current_thread_info_set[smp_processor_id()] = new_ti;
 219         last = (_switch(old_ti, new_ti))->task;
 220
 221         local_irq_restore(flags);
 222
 223         return last;
 224 }
 225
 226 /*
 227  * Write out registers in core dump format, as defined by the
 228  * struct user_regs_struct
 229  */
 230 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
 231 {
 232         dest[0] = 0; /* r0 */
 233         memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
 234         dest[32] = regs->pc;
 235         dest[33] = regs->sr;
 236         dest[34] = 0;
 237         dest[35] = 0;
 238 }
 239
 240 extern void _kernel_thread_helper(void);
 241
 242 void __noreturn kernel_thread_helper(int (*fn) (void *), void *arg)
 243 {
 244         do_exit(fn(arg));
 245 }
 246
 247 /*
 248  * Create a kernel thread.
 249  */
 250 int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
 251 {
 252         struct pt_regs regs;
 253
 254         memset(&regs, 0, sizeof(regs));
 255
 256         regs.gpr[20] = (unsigned long)fn;
 257         regs.gpr[22] = (unsigned long)arg;
 258         regs.sr = mfspr(SPR_SR);
 259         regs.pc = (unsigned long)_kernel_thread_helper;
 260
 261         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 262                        0, &regs, 0, NULL, NULL);
 263 }
 264
 265 /*
 266  * sys_execve() executes a new program.
 267  */
 268 asmlinkage long _sys_execve(const char __user *name,
 269                             const char __user * const __user *argv,
 270                             const char __user * const __user *envp,
 271                             struct pt_regs *regs)
 272 {
 273         int error;
 274         struct filename *filename;
 275
 276         filename = getname(name);
 277         error = PTR_ERR(filename);
 278
 279         if (IS_ERR(filename))
 280                 goto out;
 281
 282         error = do_execve(filename->name, argv, envp, regs);
 283         putname(filename);
 284
 285 out:
 286         return error;
 287 }
 288
 289 unsigned long get_wchan(struct task_struct *p)
 290 {
 291         /* TODO */
 292
 293         return 0;
 294 }
 295
 296 int kernel_execve(const char *filename, char *const argv[], char *const envp[])
 297 {
 298         register long __res asm("r11") = __NR_execve;
 299         register long __a asm("r3") = (long)(filename);
 300         register long __b asm("r4") = (long)(argv);
 301         register long __c asm("r5") = (long)(envp);
 302         __asm__ volatile ("l.sys 1"
 303                           : "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)
 304                           : "0"(__res), "1"(__a), "2"(__b), "3"(__c)
 305                           : "r6", "r7", "r8", "r12", "r13", "r15",
 306                             "r17", "r19", "r21", "r23", "r25", "r27",
 307                             "r29", "r31");
 308         __asm__ volatile ("l.nop");
 309         return __res;
 310 }