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/module.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 unsigned long thread_saved_pc(struct task_struct *t)
 114 {
 115         return (unsigned long)user_regs(t->stack)->pc;
 116 }
 117
 118 void release_thread(struct task_struct *dead_task)
 119 {
 120 }
 121
 122 /*
 123  * Copy the thread-specific (arch specific) info from the current
 124  * process to the new one p
 125  */
 126 extern asmlinkage void ret_from_fork(void);
 127
 128 /*
 129  * copy_thread
 130  * @clone_flags: flags
 131  * @usp: user stack pointer or fn for kernel thread
 132  * @arg: arg to fn for kernel thread; always NULL for userspace thread
 133  * @p: the newly created task
 134  * @regs: CPU context to copy for userspace thread; always NULL for kthread
 135  *
 136  * At the top of a newly initialized kernel stack are two stacked pt_reg
 137  * structures.  The first (topmost) is the userspace context of the thread.
 138  * The second is the kernelspace context of the thread.
 139  *
 140  * A kernel thread will not be returning to userspace, so the topmost pt_regs
 141  * struct can be uninitialized; it _does_ need to exist, though, because
 142  * a kernel thread can become a userspace thread by doing a kernel_execve, in
 143  * which case the topmost context will be initialized and used for 'returning'
 144  * to userspace.
 145  *
 146  * The second pt_reg struct needs to be initialized to 'return' to
 147  * ret_from_fork.  A kernel thread will need to set r20 to the address of
 148  * a function to call into (with arg in r22); userspace threads need to set
 149  * r20 to NULL in which case ret_from_fork will just continue a return to
 150  * userspace.
 151  *
 152  * A kernel thread 'fn' may return; this is effectively what happens when
 153  * kernel_execve is called.  In that case, the userspace pt_regs must have
 154  * been initialized (which kernel_execve takes care of, see start_thread
 155  * below); ret_from_fork will then continue its execution causing the
 156  * 'kernel thread' to return to userspace as a userspace thread.
 157  */
 158
 159 int
 160 copy_thread(unsigned long clone_flags, unsigned long usp,
 161             unsigned long arg, struct task_struct *p)
 162 {
 163         struct pt_regs *userregs;
 164         struct pt_regs *kregs;
 165         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 166         unsigned long top_of_kernel_stack;
 167
 168         top_of_kernel_stack = sp;
 169
 170         p->set_child_tid = p->clear_child_tid = NULL;
 171
 172         /* Locate userspace context on stack... */
 173         sp -= STACK_FRAME_OVERHEAD;     /* redzone */
 174         sp -= sizeof(struct pt_regs);
 175         userregs = (struct pt_regs *) sp;
 176
 177         /* ...and kernel context */
 178         sp -= STACK_FRAME_OVERHEAD;     /* redzone */
 179         sp -= sizeof(struct pt_regs);
 180         kregs = (struct pt_regs *)sp;
 181
 182         if (unlikely(p->flags & PF_KTHREAD)) {
 183                 memset(kregs, 0, sizeof(struct pt_regs));
 184                 kregs->gpr[20] = usp; /* fn, kernel thread */
 185                 kregs->gpr[22] = arg;
 186         } else {
 187                 *userregs = *current_pt_regs();
 188
 189                 if (usp)
 190                         userregs->sp = usp;
 191
 192                 /*
 193                  * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
 194                  *
 195                  * The kernel entry is:
 196                  *      int clone (long flags, void *child_stack, int *parent_tid,
 197                  *              int *child_tid, struct void *tls)
 198                  *
 199                  * This makes the source r7 in the kernel registers.
 200                  */
 201                 if (clone_flags & CLONE_SETTLS)
 202                         userregs->gpr[10] = userregs->gpr[7];
 203
 204                 userregs->gpr[11] = 0;  /* Result from fork() */
 205
 206                 kregs->gpr[20] = 0;     /* Userspace thread */
 207         }
 208
 209         /*
 210          * _switch wants the kernel stack page in pt_regs->sp so that it
 211          * can restore it to thread_info->ksp... see _switch for details.
 212          */
 213         kregs->sp = top_of_kernel_stack;
 214         kregs->gpr[9] = (unsigned long)ret_from_fork;
 215
 216         task_thread_info(p)->ksp = (unsigned long)kregs;
 217
 218         return 0;
 219 }
 220
 221 /*
 222  * Set up a thread for executing a new program
 223  */
 224 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 225 {
 226         unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
 227
 228         memset(regs, 0, sizeof(struct pt_regs));
 229
 230         regs->pc = pc;
 231         regs->sr = sr;
 232         regs->sp = sp;
 233 }
 234
 235 /* Fill in the fpu structure for a core dump.  */
 236 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
 237 {
 238         /* TODO */
 239         return 0;
 240 }
 241
 242 extern struct thread_info *_switch(struct thread_info *old_ti,
 243                                    struct thread_info *new_ti);
 244 extern int lwa_flag;
 245
 246 struct task_struct *__switch_to(struct task_struct *old,
 247                                 struct task_struct *new)
 248 {
 249         struct task_struct *last;
 250         struct thread_info *new_ti, *old_ti;
 251         unsigned long flags;
 252
 253         local_irq_save(flags);
 254
 255         /* current_set is an array of saved current pointers
 256          * (one for each cpu). we need them at user->kernel transition,
 257          * while we save them at kernel->user transition
 258          */
 259         new_ti = new->stack;
 260         old_ti = old->stack;
 261
 262         lwa_flag = 0;
 263
 264         current_thread_info_set[smp_processor_id()] = new_ti;
 265         last = (_switch(old_ti, new_ti))->task;
 266
 267         local_irq_restore(flags);
 268
 269         return last;
 270 }
 271
 272 /*
 273  * Write out registers in core dump format, as defined by the
 274  * struct user_regs_struct
 275  */
 276 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
 277 {
 278         dest[0] = 0; /* r0 */
 279         memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
 280         dest[32] = regs->pc;
 281         dest[33] = regs->sr;
 282         dest[34] = 0;
 283         dest[35] = 0;
 284 }
 285
 286 unsigned long get_wchan(struct task_struct *p)
 287 {
 288         /* TODO */
 289
 290         return 0;
 291 }