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 #include <asm/uaccess.h> /* for USER_DS macros */
  19 #include <asm/cacheflush.h>
  20
  21 void show_regs(struct pt_regs *regs)
  22 {
  23         printk(KERN_INFO " Registers dump: mode=%X\r\n", regs->pt_mode);
  24         printk(KERN_INFO " r1=%08lX, r2=%08lX, r3=%08lX, r4=%08lX\n",
  25                                 regs->r1, regs->r2, regs->r3, regs->r4);
  26         printk(KERN_INFO " r5=%08lX, r6=%08lX, r7=%08lX, r8=%08lX\n",
  27                                 regs->r5, regs->r6, regs->r7, regs->r8);
  28         printk(KERN_INFO " r9=%08lX, r10=%08lX, r11=%08lX, r12=%08lX\n",
  29                                 regs->r9, regs->r10, regs->r11, regs->r12);
  30         printk(KERN_INFO " r13=%08lX, r14=%08lX, r15=%08lX, r16=%08lX\n",
  31                                 regs->r13, regs->r14, regs->r15, regs->r16);
  32         printk(KERN_INFO " r17=%08lX, r18=%08lX, r19=%08lX, r20=%08lX\n",
  33                                 regs->r17, regs->r18, regs->r19, regs->r20);
  34         printk(KERN_INFO " r21=%08lX, r22=%08lX, r23=%08lX, r24=%08lX\n",
  35                                 regs->r21, regs->r22, regs->r23, regs->r24);
  36         printk(KERN_INFO " r25=%08lX, r26=%08lX, r27=%08lX, r28=%08lX\n",
  37                                 regs->r25, regs->r26, regs->r27, regs->r28);
  38         printk(KERN_INFO " r29=%08lX, r30=%08lX, r31=%08lX, rPC=%08lX\n",
  39                                 regs->r29, regs->r30, regs->r31, regs->pc);
  40         printk(KERN_INFO " msr=%08lX, ear=%08lX, esr=%08lX, fsr=%08lX\n",
  41                                 regs->msr, regs->ear, regs->esr, regs->fsr);
  42 }
  43
  44 void (*pm_idle)(void);
  45 void (*pm_power_off)(void) = NULL;
  46 EXPORT_SYMBOL(pm_power_off);
  47
  48 static int hlt_counter = 1;
  49
  50 void disable_hlt(void)
  51 {
  52         hlt_counter++;
  53 }
  54 EXPORT_SYMBOL(disable_hlt);
  55
  56 void enable_hlt(void)
  57 {
  58         hlt_counter--;
  59 }
  60 EXPORT_SYMBOL(enable_hlt);
  61
  62 static int __init nohlt_setup(char *__unused)
  63 {
  64         hlt_counter = 1;
  65         return 1;
  66 }
  67 __setup("nohlt", nohlt_setup);
  68
  69 static int __init hlt_setup(char *__unused)
  70 {
  71         hlt_counter = 0;
  72         return 1;
  73 }
  74 __setup("hlt", hlt_setup);
  75
  76 void default_idle(void)
  77 {
  78         if (!hlt_counter) {
  79                 clear_thread_flag(TIF_POLLING_NRFLAG);
  80                 smp_mb__after_clear_bit();
  81                 local_irq_disable();
  82                 while (!need_resched())
  83                         cpu_sleep();
  84                 local_irq_enable();
  85                 set_thread_flag(TIF_POLLING_NRFLAG);
  86         } else
  87                 while (!need_resched())
  88                         cpu_relax();
  89 }
  90
  91 void cpu_idle(void)
  92 {
  93         set_thread_flag(TIF_POLLING_NRFLAG);
  94
  95         /* endless idle loop with no priority at all */
  96         while (1) {
  97                 void (*idle)(void) = pm_idle;
  98
  99                 if (!idle)
 100                         idle = default_idle;
 101
 102                 tick_nohz_stop_sched_tick(1);
 103                 while (!need_resched())
 104                         idle();
 105                 tick_nohz_restart_sched_tick();
 106
 107                 preempt_enable_no_resched();
 108                 schedule();
 109                 preempt_disable();
 110                 check_pgt_cache();
 111         }
 112 }
 113
 114 void flush_thread(void)
 115 {
 116 }
 117
 118 int copy_thread(unsigned long clone_flags, unsigned long usp,
 119                 unsigned long unused,
 120                 struct task_struct *p, struct pt_regs *regs)
 121 {
 122         struct pt_regs *childregs = task_pt_regs(p);
 123         struct thread_info *ti = task_thread_info(p);
 124
 125         *childregs = *regs;
 126         if (user_mode(regs))
 127                 childregs->r1 = usp;
 128         else
 129                 childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;
 130
 131 #ifndef CONFIG_MMU
 132         memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 133         ti->cpu_context.r1 = (unsigned long)childregs;
 134         ti->cpu_context.msr = (unsigned long)childregs->msr;
 135 #else
 136
 137         /* if creating a kernel thread then update the current reg (we don't
 138          * want to use the parent's value when restoring by POP_STATE) */
 139         if (kernel_mode(regs))
 140                 /* save new current on stack to use POP_STATE */
 141                 childregs->CURRENT_TASK = (unsigned long)p;
 142         /* if returning to user then use the parent's value of this register */
 143
 144         /* if we're creating a new kernel thread then just zeroing all
 145          * the registers. That's OK for a brand new thread.*/
 146         /* Pls. note that some of them will be restored in POP_STATE */
 147         if (kernel_mode(regs))
 148                 memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 149         /* if this thread is created for fork/vfork/clone, then we want to
 150          * restore all the parent's context */
 151         /* in addition to the registers which will be restored by POP_STATE */
 152         else {
 153                 ti->cpu_context = *(struct cpu_context *)regs;
 154                 childregs->msr |= MSR_UMS;
 155         }
 156
 157         /* FIXME STATE_SAVE_PT_OFFSET; */
 158         ti->cpu_context.r1  = (unsigned long)childregs - STATE_SAVE_ARG_SPACE;
 159         /* we should consider the fact that childregs is a copy of the parent
 160          * regs which were saved immediately after entering the kernel state
 161          * before enabling VM. This MSR will be restored in switch_to and
 162          * RETURN() and we want to have the right machine state there
 163          * specifically this state must have INTs disabled before and enabled
 164          * after performing rtbd
 165          * compose the right MSR for RETURN(). It will work for switch_to also
 166          * excepting for VM and UMS
 167          * don't touch UMS , CARRY and cache bits
 168          * right now MSR is a copy of parent one */
 169         childregs->msr |= MSR_BIP;
 170         childregs->msr &= ~MSR_EIP;
 171         childregs->msr |= MSR_IE;
 172         childregs->msr &= ~MSR_VM;
 173         childregs->msr |= MSR_VMS;
 174         childregs->msr |= MSR_EE; /* exceptions will be enabled*/
 175
 176         ti->cpu_context.msr = (childregs->msr|MSR_VM);
 177         ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
 178 #endif
 179         ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 180
 181         if (clone_flags & CLONE_SETTLS)
 182                 ;
 183
 184         return 0;
 185 }
 186
 187 #ifndef CONFIG_MMU
 188 /*
 189  * Return saved PC of a blocked thread.
 190  */
 191 unsigned long thread_saved_pc(struct task_struct *tsk)
 192 {
 193         struct cpu_context *ctx =
 194                 &(((struct thread_info *)(tsk->stack))->cpu_context);
 195
 196         /* Check whether the thread is blocked in resume() */
 197         if (in_sched_functions(ctx->r15))
 198                 return (unsigned long)ctx->r15;
 199         else
 200                 return ctx->r14;
 201 }
 202 #endif
 203
 204 static void kernel_thread_helper(int (*fn)(void *), void *arg)
 205 {
 206         fn(arg);
 207         do_exit(-1);
 208 }
 209
 210 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 211 {
 212         struct pt_regs regs;
 213
 214         memset(&regs, 0, sizeof(regs));
 215         /* store them in non-volatile registers */
 216         regs.r5 = (unsigned long)fn;
 217         regs.r6 = (unsigned long)arg;
 218         local_save_flags(regs.msr);
 219         regs.pc = (unsigned long)kernel_thread_helper;
 220         regs.pt_mode = 1;
 221
 222         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 223                         &regs, 0, NULL, NULL);
 224 }
 225 EXPORT_SYMBOL_GPL(kernel_thread);
 226
 227 unsigned long get_wchan(struct task_struct *p)
 228 {
 229 /* TBD (used by procfs) */
 230         return 0;
 231 }
 232
 233 /* Set up a thread for executing a new program */
 234 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
 235 {
 236         set_fs(USER_DS);
 237         regs->pc = pc;
 238         regs->r1 = usp;
 239         regs->pt_mode = 0;
 240 #ifdef CONFIG_MMU
 241         regs->msr |= MSR_UMS;
 242 #endif
 243 }
 244
 245 #ifdef CONFIG_MMU
 246 #include <linux/elfcore.h>
 247 /*
 248  * Set up a thread for executing a new program
 249  */
 250 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 251 {
 252         return 0; /* MicroBlaze has no separate FPU registers */
 253 }
 254 #endif /* CONFIG_MMU */