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/pgalloc.h>
  17 #include <asm/uaccess.h> /* for USER_DS macros */
  18 #include <asm/cacheflush.h>
  19
  20 void show_regs(struct pt_regs *regs)
  21 {
  22         printk(KERN_INFO " Registers dump: mode=%X\r\n", regs->pt_mode);
  23         printk(KERN_INFO " r1=%08lX, r2=%08lX, r3=%08lX, r4=%08lX\n",
  24                                 regs->r1, regs->r2, regs->r3, regs->r4);
  25         printk(KERN_INFO " r5=%08lX, r6=%08lX, r7=%08lX, r8=%08lX\n",
  26                                 regs->r5, regs->r6, regs->r7, regs->r8);
  27         printk(KERN_INFO " r9=%08lX, r10=%08lX, r11=%08lX, r12=%08lX\n",
  28                                 regs->r9, regs->r10, regs->r11, regs->r12);
  29         printk(KERN_INFO " r13=%08lX, r14=%08lX, r15=%08lX, r16=%08lX\n",
  30                                 regs->r13, regs->r14, regs->r15, regs->r16);
  31         printk(KERN_INFO " r17=%08lX, r18=%08lX, r19=%08lX, r20=%08lX\n",
  32                                 regs->r17, regs->r18, regs->r19, regs->r20);
  33         printk(KERN_INFO " r21=%08lX, r22=%08lX, r23=%08lX, r24=%08lX\n",
  34                                 regs->r21, regs->r22, regs->r23, regs->r24);
  35         printk(KERN_INFO " r25=%08lX, r26=%08lX, r27=%08lX, r28=%08lX\n",
  36                                 regs->r25, regs->r26, regs->r27, regs->r28);
  37         printk(KERN_INFO " r29=%08lX, r30=%08lX, r31=%08lX, rPC=%08lX\n",
  38                                 regs->r29, regs->r30, regs->r31, regs->pc);
  39         printk(KERN_INFO " msr=%08lX, ear=%08lX, esr=%08lX, fsr=%08lX\n",
  40                                 regs->msr, regs->ear, regs->esr, regs->fsr);
  41 }
  42
  43 void (*pm_idle)(void);
  44 void (*pm_power_off)(void) = NULL;
  45 EXPORT_SYMBOL(pm_power_off);
  46
  47 static int hlt_counter = 1;
  48
  49 void disable_hlt(void)
  50 {
  51         hlt_counter++;
  52 }
  53 EXPORT_SYMBOL(disable_hlt);
  54
  55 void enable_hlt(void)
  56 {
  57         hlt_counter--;
  58 }
  59 EXPORT_SYMBOL(enable_hlt);
  60
  61 static int __init nohlt_setup(char *__unused)
  62 {
  63         hlt_counter = 1;
  64         return 1;
  65 }
  66 __setup("nohlt", nohlt_setup);
  67
  68 static int __init hlt_setup(char *__unused)
  69 {
  70         hlt_counter = 0;
  71         return 1;
  72 }
  73 __setup("hlt", hlt_setup);
  74
  75 void default_idle(void)
  76 {
  77         if (likely(hlt_counter)) {
  78                 local_irq_disable();
  79                 stop_critical_timings();
  80                 cpu_relax();
  81                 start_critical_timings();
  82                 local_irq_enable();
  83         } else {
  84                 clear_thread_flag(TIF_POLLING_NRFLAG);
  85                 smp_mb__after_clear_bit();
  86                 local_irq_disable();
  87                 while (!need_resched())
  88                         cpu_sleep();
  89                 local_irq_enable();
  90                 set_thread_flag(TIF_POLLING_NRFLAG);
  91         }
  92 }
  93
  94 void cpu_idle(void)
  95 {
  96         set_thread_flag(TIF_POLLING_NRFLAG);
  97
  98         /* endless idle loop with no priority at all */
  99         while (1) {
 100                 void (*idle)(void) = pm_idle;
 101
 102                 if (!idle)
 103                         idle = default_idle;
 104
 105                 tick_nohz_idle_enter();
 106                 rcu_idle_enter();
 107                 while (!need_resched())
 108                         idle();
 109                 rcu_idle_exit();
 110                 tick_nohz_idle_exit();
 111
 112                 schedule_preempt_disabled();
 113                 check_pgt_cache();
 114         }
 115 }
 116
 117 void flush_thread(void)
 118 {
 119 }
 120
 121 int copy_thread(unsigned long clone_flags, unsigned long usp,
 122                 unsigned long unused,
 123                 struct task_struct *p, struct pt_regs *regs)
 124 {
 125         struct pt_regs *childregs = task_pt_regs(p);
 126         struct thread_info *ti = task_thread_info(p);
 127
 128         *childregs = *regs;
 129         if (user_mode(regs))
 130                 childregs->r1 = usp;
 131         else
 132                 childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;
 133
 134 #ifndef CONFIG_MMU
 135         memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 136         ti->cpu_context.r1 = (unsigned long)childregs;
 137         ti->cpu_context.msr = (unsigned long)childregs->msr;
 138 #else
 139
 140         /* if creating a kernel thread then update the current reg (we don't
 141          * want to use the parent's value when restoring by POP_STATE) */
 142         if (kernel_mode(regs))
 143                 /* save new current on stack to use POP_STATE */
 144                 childregs->CURRENT_TASK = (unsigned long)p;
 145         /* if returning to user then use the parent's value of this register */
 146
 147         /* if we're creating a new kernel thread then just zeroing all
 148          * the registers. That's OK for a brand new thread.*/
 149         /* Pls. note that some of them will be restored in POP_STATE */
 150         if (kernel_mode(regs))
 151                 memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 152         /* if this thread is created for fork/vfork/clone, then we want to
 153          * restore all the parent's context */
 154         /* in addition to the registers which will be restored by POP_STATE */
 155         else {
 156                 ti->cpu_context = *(struct cpu_context *)regs;
 157                 childregs->msr |= MSR_UMS;
 158         }
 159
 160         /* FIXME STATE_SAVE_PT_OFFSET; */
 161         ti->cpu_context.r1  = (unsigned long)childregs;
 162         /* we should consider the fact that childregs is a copy of the parent
 163          * regs which were saved immediately after entering the kernel state
 164          * before enabling VM. This MSR will be restored in switch_to and
 165          * RETURN() and we want to have the right machine state there
 166          * specifically this state must have INTs disabled before and enabled
 167          * after performing rtbd
 168          * compose the right MSR for RETURN(). It will work for switch_to also
 169          * excepting for VM and UMS
 170          * don't touch UMS , CARRY and cache bits
 171          * right now MSR is a copy of parent one */
 172         childregs->msr |= MSR_BIP;
 173         childregs->msr &= ~MSR_EIP;
 174         childregs->msr |= MSR_IE;
 175         childregs->msr &= ~MSR_VM;
 176         childregs->msr |= MSR_VMS;
 177         childregs->msr |= MSR_EE; /* exceptions will be enabled*/
 178
 179         ti->cpu_context.msr = (childregs->msr|MSR_VM);
 180         ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
 181         ti->cpu_context.msr &= ~MSR_IE;
 182 #endif
 183         ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 184
 185         /*
 186          *  r21 is the thread reg, r10 is 6th arg to clone
 187          *  which contains TLS area
 188          */
 189         if (clone_flags & CLONE_SETTLS)
 190                 childregs->r21 = childregs->r10;
 191
 192         return 0;
 193 }
 194
 195 #ifndef CONFIG_MMU
 196 /*
 197  * Return saved PC of a blocked thread.
 198  */
 199 unsigned long thread_saved_pc(struct task_struct *tsk)
 200 {
 201         struct cpu_context *ctx =
 202                 &(((struct thread_info *)(tsk->stack))->cpu_context);
 203
 204         /* Check whether the thread is blocked in resume() */
 205         if (in_sched_functions(ctx->r15))
 206                 return (unsigned long)ctx->r15;
 207         else
 208                 return ctx->r14;
 209 }
 210 #endif
 211
 212 static void kernel_thread_helper(int (*fn)(void *), void *arg)
 213 {
 214         fn(arg);
 215         do_exit(-1);
 216 }
 217
 218 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 219 {
 220         struct pt_regs regs;
 221
 222         memset(&regs, 0, sizeof(regs));
 223         /* store them in non-volatile registers */
 224         regs.r5 = (unsigned long)fn;
 225         regs.r6 = (unsigned long)arg;
 226         local_save_flags(regs.msr);
 227         regs.pc = (unsigned long)kernel_thread_helper;
 228         regs.pt_mode = 1;
 229
 230         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 231                         &regs, 0, NULL, NULL);
 232 }
 233 EXPORT_SYMBOL_GPL(kernel_thread);
 234
 235 unsigned long get_wchan(struct task_struct *p)
 236 {
 237 /* TBD (used by procfs) */
 238         return 0;
 239 }
 240
 241 /* Set up a thread for executing a new program */
 242 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
 243 {
 244         regs->pc = pc;
 245         regs->r1 = usp;
 246         regs->pt_mode = 0;
 247 #ifdef CONFIG_MMU
 248         regs->msr |= MSR_UMS;
 249 #endif
 250 }
 251
 252 #ifdef CONFIG_MMU
 253 #include <linux/elfcore.h>
 254 /*
 255  * Set up a thread for executing a new program
 256  */
 257 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 258 {
 259         return 0; /* MicroBlaze has no separate FPU registers */
 260 }
 261 #endif /* CONFIG_MMU */