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/sched/debug.h>
  26 #include <linux/sched/task.h>
  27 #include <linux/sched/task_stack.h>
  28 #include <linux/kernel.h>
  29 #include <linux/export.h>
  30 #include <linux/mm.h>
  31 #include <linux/stddef.h>
  32 #include <linux/unistd.h>
  33 #include <linux/ptrace.h>
  34 #include <linux/slab.h>
  35 #include <linux/elfcore.h>
  36 #include <linux/interrupt.h>
  37 #include <linux/delay.h>
  38 #include <linux/init_task.h>
  39 #include <linux/mqueue.h>
  40 #include <linux/fs.h>
  41
  42 #include <linux/uaccess.h>
  43 #include <asm/pgtable.h>
  44 #include <asm/io.h>
  45 #include <asm/processor.h>
  46 #include <asm/spr_defs.h>
  47
  48 #include <linux/smp.h>
  49
  50 /*
  51  * Pointer to Current thread info structure.
  52  *
  53  * Used at user space -> kernel transitions.
  54  */
  55 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
  56
  57 void machine_restart(void)
  58 {
  59         printk(KERN_INFO "*** MACHINE RESTART ***\n");
  60         __asm__("l.nop 1");
  61 }
  62
  63 /*
  64  * Similar to machine_power_off, but don't shut off power.  Add code
  65  * here to freeze the system for e.g. post-mortem debug purpose when
  66  * possible.  This halt has nothing to do with the idle halt.
  67  */
  68 void machine_halt(void)
  69 {
  70         printk(KERN_INFO "*** MACHINE HALT ***\n");
  71         __asm__("l.nop 1");
  72 }
  73
  74 /* If or when software power-off is implemented, add code here.  */
  75 void machine_power_off(void)
  76 {
  77         printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
  78         __asm__("l.nop 1");
  79 }
  80
  81 /*
  82  * Send the doze signal to the cpu if available.
  83  * Make sure, that all interrupts are enabled
  84  */
  85 void arch_cpu_idle(void)
  86 {
  87         local_irq_enable();
  88         if (mfspr(SPR_UPR) & SPR_UPR_PMP)
  89                 mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
  90 }
  91
  92 void (*pm_power_off) (void) = machine_power_off;
  93 EXPORT_SYMBOL(pm_power_off);
  94
  95 /*
  96  * When a process does an "exec", machine state like FPU and debug
  97  * registers need to be reset.  This is a hook function for that.
  98  * Currently we don't have any such state to reset, so this is empty.
  99  */
 100 void flush_thread(void)
 101 {
 102 }
 103
 104 void show_regs(struct pt_regs *regs)
 105 {
 106         extern void show_registers(struct pt_regs *regs);
 107
 108         show_regs_print_info(KERN_DEFAULT);
 109         /* __PHX__ cleanup this mess */
 110         show_registers(regs);
 111 }
 112
 113 void release_thread(struct task_struct *dead_task)
 114 {
 115 }
 116
 117 /*
 118  * Copy the thread-specific (arch specific) info from the current
 119  * process to the new one p
 120  */
 121 extern asmlinkage void ret_from_fork(void);
 122
 123 /*
 124  * copy_thread
 125  * @clone_flags: flags
 126  * @usp: user stack pointer or fn for kernel thread
 127  * @arg: arg to fn for kernel thread; always NULL for userspace thread
 128  * @p: the newly created task
 129  * @regs: CPU context to copy for userspace thread; always NULL for kthread
 130  *
 131  * At the top of a newly initialized kernel stack are two stacked pt_reg
 132  * structures.  The first (topmost) is the userspace context of the thread.
 133  * The second is the kernelspace context of the thread.
 134  *
 135  * A kernel thread will not be returning to userspace, so the topmost pt_regs
 136  * struct can be uninitialized; it _does_ need to exist, though, because
 137  * a kernel thread can become a userspace thread by doing a kernel_execve, in
 138  * which case the topmost context will be initialized and used for 'returning'
 139  * to userspace.
 140  *
 141  * The second pt_reg struct needs to be initialized to 'return' to
 142  * ret_from_fork.  A kernel thread will need to set r20 to the address of
 143  * a function to call into (with arg in r22); userspace threads need to set
 144  * r20 to NULL in which case ret_from_fork will just continue a return to
 145  * userspace.
 146  *
 147  * A kernel thread 'fn' may return; this is effectively what happens when
 148  * kernel_execve is called.  In that case, the userspace pt_regs must have
 149  * been initialized (which kernel_execve takes care of, see start_thread
 150  * below); ret_from_fork will then continue its execution causing the
 151  * 'kernel thread' to return to userspace as a userspace thread.
 152  */
 153
 154 int
 155 copy_thread(unsigned long clone_flags, unsigned long usp,
 156             unsigned long arg, struct task_struct *p)
 157 {
 158         struct pt_regs *userregs;
 159         struct pt_regs *kregs;
 160         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 161         unsigned long top_of_kernel_stack;
 162
 163         top_of_kernel_stack = sp;
 164
 165         /* Locate userspace context on stack... */
 166         sp -= STACK_FRAME_OVERHEAD;     /* redzone */
 167         sp -= sizeof(struct pt_regs);
 168         userregs = (struct pt_regs *) sp;
 169
 170         /* ...and kernel context */
 171         sp -= STACK_FRAME_OVERHEAD;     /* redzone */
 172         sp -= sizeof(struct pt_regs);
 173         kregs = (struct pt_regs *)sp;
 174
 175         if (unlikely(p->flags & PF_KTHREAD)) {
 176                 memset(kregs, 0, sizeof(struct pt_regs));
 177                 kregs->gpr[20] = usp; /* fn, kernel thread */
 178                 kregs->gpr[22] = arg;
 179         } else {
 180                 *userregs = *current_pt_regs();
 181
 182                 if (usp)
 183                         userregs->sp = usp;
 184
 185                 /*
 186                  * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
 187                  *
 188                  * The kernel entry is:
 189                  *      int clone (long flags, void *child_stack, int *parent_tid,
 190                  *              int *child_tid, struct void *tls)
 191                  *
 192                  * This makes the source r7 in the kernel registers.
 193                  */
 194                 if (clone_flags & CLONE_SETTLS)
 195                         userregs->gpr[10] = userregs->gpr[7];
 196
 197                 userregs->gpr[11] = 0;  /* Result from fork() */
 198
 199                 kregs->gpr[20] = 0;     /* Userspace thread */
 200         }
 201
 202         /*
 203          * _switch wants the kernel stack page in pt_regs->sp so that it
 204          * can restore it to thread_info->ksp... see _switch for details.
 205          */
 206         kregs->sp = top_of_kernel_stack;
 207         kregs->gpr[9] = (unsigned long)ret_from_fork;
 208
 209         task_thread_info(p)->ksp = (unsigned long)kregs;
 210
 211         return 0;
 212 }
 213
 214 /*
 215  * Set up a thread for executing a new program
 216  */
 217 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 218 {
 219         unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
 220
 221         memset(regs, 0, sizeof(struct pt_regs));
 222
 223         regs->pc = pc;
 224         regs->sr = sr;
 225         regs->sp = sp;
 226 }
 227
 228 /* Fill in the fpu structure for a core dump.  */
 229 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
 230 {
 231         /* TODO */
 232         return 0;
 233 }
 234
 235 extern struct thread_info *_switch(struct thread_info *old_ti,
 236                                    struct thread_info *new_ti);
 237 extern int lwa_flag;
 238
 239 struct task_struct *__switch_to(struct task_struct *old,
 240                                 struct task_struct *new)
 241 {
 242         struct task_struct *last;
 243         struct thread_info *new_ti, *old_ti;
 244         unsigned long flags;
 245
 246         local_irq_save(flags);
 247
 248         /* current_set is an array of saved current pointers
 249          * (one for each cpu). we need them at user->kernel transition,
 250          * while we save them at kernel->user transition
 251          */
 252         new_ti = new->stack;
 253         old_ti = old->stack;
 254
 255         lwa_flag = 0;
 256
 257         current_thread_info_set[smp_processor_id()] = new_ti;
 258         last = (_switch(old_ti, new_ti))->task;
 259
 260         local_irq_restore(flags);
 261
 262         return last;
 263 }
 264
 265 /*
 266  * Write out registers in core dump format, as defined by the
 267  * struct user_regs_struct
 268  */
 269 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
 270 {
 271         dest[0] = 0; /* r0 */
 272         memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
 273         dest[32] = regs->pc;
 274         dest[33] = regs->sr;
 275         dest[34] = 0;
 276         dest[35] = 0;
 277 }
 278
 279 unsigned long get_wchan(struct task_struct *p)
 280 {
 281         /* TODO */
 282
 283         return 0;
 284 }