arch/microblaze/kernel/process.c

   1 /*
   2  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   3  * Copyright (C) 2008-2009 PetaLogix
   4  * Copyright (C) 2006 Atmark Techno, Inc.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License. See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/pm.h>
  14 #include <linux/tick.h>
  15 #include <linux/bitops.h>
  16 #include <asm/system.h>
  17 #include <asm/pgalloc.h>
  18
  19 void show_regs(struct pt_regs *regs)
  20 {
  21         printk(KERN_INFO " Registers dump: mode=%X\r\n", regs->pt_mode);
  22         printk(KERN_INFO " r1=%08lX, r2=%08lX, r3=%08lX, r4=%08lX\n",
  23                                 regs->r1, regs->r2, regs->r3, regs->r4);
  24         printk(KERN_INFO " r5=%08lX, r6=%08lX, r7=%08lX, r8=%08lX\n",
  25                                 regs->r5, regs->r6, regs->r7, regs->r8);
  26         printk(KERN_INFO " r9=%08lX, r10=%08lX, r11=%08lX, r12=%08lX\n",
  27                                 regs->r9, regs->r10, regs->r11, regs->r12);
  28         printk(KERN_INFO " r13=%08lX, r14=%08lX, r15=%08lX, r16=%08lX\n",
  29                                 regs->r13, regs->r14, regs->r15, regs->r16);
  30         printk(KERN_INFO " r17=%08lX, r18=%08lX, r19=%08lX, r20=%08lX\n",
  31                                 regs->r17, regs->r18, regs->r19, regs->r20);
  32         printk(KERN_INFO " r21=%08lX, r22=%08lX, r23=%08lX, r24=%08lX\n",
  33                                 regs->r21, regs->r22, regs->r23, regs->r24);
  34         printk(KERN_INFO " r25=%08lX, r26=%08lX, r27=%08lX, r28=%08lX\n",
  35                                 regs->r25, regs->r26, regs->r27, regs->r28);
  36         printk(KERN_INFO " r29=%08lX, r30=%08lX, r31=%08lX, rPC=%08lX\n",
  37                                 regs->r29, regs->r30, regs->r31, regs->pc);
  38         printk(KERN_INFO " msr=%08lX, ear=%08lX, esr=%08lX, fsr=%08lX\n",
  39                                 regs->msr, regs->ear, regs->esr, regs->fsr);
  40 }
  41
  42 void (*pm_idle)(void);
  43 void (*pm_power_off)(void) = NULL;
  44 EXPORT_SYMBOL(pm_power_off);
  45
  46 static int hlt_counter = 1;
  47
  48 void disable_hlt(void)
  49 {
  50         hlt_counter++;
  51 }
  52 EXPORT_SYMBOL(disable_hlt);
  53
  54 void enable_hlt(void)
  55 {
  56         hlt_counter--;
  57 }
  58 EXPORT_SYMBOL(enable_hlt);
  59
  60 static int __init nohlt_setup(char *__unused)
  61 {
  62         hlt_counter = 1;
  63         return 1;
  64 }
  65 __setup("nohlt", nohlt_setup);
  66
  67 static int __init hlt_setup(char *__unused)
  68 {
  69         hlt_counter = 0;
  70         return 1;
  71 }
  72 __setup("hlt", hlt_setup);
  73
  74 void default_idle(void)
  75 {
  76         if (!hlt_counter) {
  77                 clear_thread_flag(TIF_POLLING_NRFLAG);
  78                 smp_mb__after_clear_bit();
  79                 local_irq_disable();
  80                 while (!need_resched())
  81                         cpu_sleep();
  82                 local_irq_enable();
  83                 set_thread_flag(TIF_POLLING_NRFLAG);
  84         } else
  85                 while (!need_resched())
  86                         cpu_relax();
  87 }
  88
  89 void cpu_idle(void)
  90 {
  91         set_thread_flag(TIF_POLLING_NRFLAG);
  92
  93         /* endless idle loop with no priority at all */
  94         while (1) {
  95                 void (*idle)(void) = pm_idle;
  96
  97                 if (!idle)
  98                         idle = default_idle;
  99
 100                 tick_nohz_stop_sched_tick(1);
 101                 while (!need_resched())
 102                         idle();
 103                 tick_nohz_restart_sched_tick();
 104
 105                 preempt_enable_no_resched();
 106                 schedule();
 107                 preempt_disable();
 108                 check_pgt_cache();
 109         }
 110 }
 111
 112 void flush_thread(void)
 113 {
 114 }
 115
 116 int copy_thread(unsigned long clone_flags, unsigned long usp,
 117                 unsigned long unused,
 118                 struct task_struct *p, struct pt_regs *regs)
 119 {
 120         struct pt_regs *childregs = task_pt_regs(p);
 121         struct thread_info *ti = task_thread_info(p);
 122
 123         *childregs = *regs;
 124         if (user_mode(regs))
 125                 childregs->r1 = usp;
 126         else
 127                 childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;
 128
 129 #ifndef CONFIG_MMU
 130         memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 131         ti->cpu_context.r1 = (unsigned long)childregs;
 132         ti->cpu_context.msr = (unsigned long)childregs->msr;
 133 #else
 134
 135         /* if creating a kernel thread then update the current reg (we don't
 136          * want to use the parent's value when restoring by POP_STATE) */
 137         if (kernel_mode(regs))
 138                 /* save new current on stack to use POP_STATE */
 139                 childregs->CURRENT_TASK = (unsigned long)p;
 140         /* if returning to user then use the parent's value of this register */
 141
 142         /* if we're creating a new kernel thread then just zeroing all
 143          * the registers. That's OK for a brand new thread.*/
 144         /* Pls. note that some of them will be restored in POP_STATE */
 145         if (kernel_mode(regs))
 146                 memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 147         /* if this thread is created for fork/vfork/clone, then we want to
 148          * restore all the parent's context */
 149         /* in addition to the registers which will be restored by POP_STATE */
 150         else {
 151                 ti->cpu_context = *(struct cpu_context *)regs;
 152                 childregs->msr |= MSR_UMS;
 153         }
 154
 155         /* FIXME STATE_SAVE_PT_OFFSET; */
 156         ti->cpu_context.r1  = (unsigned long)childregs - STATE_SAVE_ARG_SPACE;
 157         /* we should consider the fact that childregs is a copy of the parent
 158          * regs which were saved immediately after entering the kernel state
 159          * before enabling VM. This MSR will be restored in switch_to and
 160          * RETURN() and we want to have the right machine state there
 161          * specifically this state must have INTs disabled before and enabled
 162          * after performing rtbd
 163          * compose the right MSR for RETURN(). It will work for switch_to also
 164          * excepting for VM and UMS
 165          * don't touch UMS , CARRY and cache bits
 166          * right now MSR is a copy of parent one */
 167         childregs->msr |= MSR_BIP;
 168         childregs->msr &= ~MSR_EIP;
 169         childregs->msr |= MSR_IE;
 170         childregs->msr &= ~MSR_VM;
 171         childregs->msr |= MSR_VMS;
 172         childregs->msr |= MSR_EE; /* exceptions will be enabled*/
 173
 174         ti->cpu_context.msr = (childregs->msr|MSR_VM);
 175         ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
 176 #endif
 177         ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 178
 179         if (clone_flags & CLONE_SETTLS)
 180                 ;
 181
 182         return 0;
 183 }
 184
 185 #ifndef CONFIG_MMU
 186 /*
 187  * Return saved PC of a blocked thread.
 188  */
 189 unsigned long thread_saved_pc(struct task_struct *tsk)
 190 {
 191         struct cpu_context *ctx =
 192                 &(((struct thread_info *)(tsk->stack))->cpu_context);
 193
 194         /* Check whether the thread is blocked in resume() */
 195         if (in_sched_functions(ctx->r15))
 196                 return (unsigned long)ctx->r15;
 197         else
 198                 return ctx->r14;
 199 }
 200 #endif
 201
 202 static void kernel_thread_helper(int (*fn)(void *), void *arg)
 203 {
 204         fn(arg);
 205         do_exit(-1);
 206 }
 207
 208 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 209 {
 210         struct pt_regs regs;
 211
 212         memset(&regs, 0, sizeof(regs));
 213         /* store them in non-volatile registers */
 214         regs.r5 = (unsigned long)fn;
 215         regs.r6 = (unsigned long)arg;
 216         local_save_flags(regs.msr);
 217         regs.pc = (unsigned long)kernel_thread_helper;
 218         regs.pt_mode = 1;
 219
 220         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 221                         &regs, 0, NULL, NULL);
 222 }
 223 EXPORT_SYMBOL_GPL(kernel_thread);
 224
 225 unsigned long get_wchan(struct task_struct *p)
 226 {
 227 /* TBD (used by procfs) */
 228         return 0;
 229 }
 230
 231 /* Set up a thread for executing a new program */
 232 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
 233 {
 234         set_fs(USER_DS);
 235         regs->pc = pc;
 236         regs->r1 = usp;
 237         regs->pt_mode = 0;
 238         regs->msr |= MSR_UMS;
 239 }
 240
 241 #ifdef CONFIG_MMU
 242 #include <linux/elfcore.h>
 243 /*
 244  * Set up a thread for executing a new program
 245  */
 246 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 247 {
 248         return 0; /* MicroBlaze has no separate FPU registers */
 249 }
 250 #endif /* CONFIG_MMU */