arch/blackfin/kernel/entry.S

   1 /*
   2  * Copyright 2004-2009 Analog Devices Inc.
   3  *
   4  * Licensed under the GPL-2 or later
   5  */
   6
   7 #include <linux/linkage.h>
   8 #include <asm/thread_info.h>
   9 #include <asm/errno.h>
  10 #include <asm/blackfin.h>
  11 #include <asm/asm-offsets.h>
  12
  13 #include <asm/context.S>
  14
  15 #ifdef CONFIG_EXCPT_IRQ_SYSC_L1
  16 .section .l1.text
  17 #else
  18 .text
  19 #endif
  20
  21 ENTRY(_ret_from_fork)
  22 #ifdef CONFIG_IPIPE
  23         /*
  24          * Hw IRQs are off on entry, and we don't want the scheduling tail
  25          * code to starve high priority domains from interrupts while it
  26          * runs. Therefore we first stall the root stage to have the
  27          * virtual interrupt state reflect IMASK.
  28          */
  29         p0.l = ___ipipe_root_status;
  30         p0.h = ___ipipe_root_status;
  31         r4 = [p0];
  32         bitset(r4, 0);
  33         [p0] = r4;
  34         /*
  35          * Then we may enable hw IRQs, allowing preemption from high
  36          * priority domains. schedule_tail() will do local_irq_enable()
  37          * since Blackfin does not define __ARCH_WANT_UNLOCKED_CTXSW, so
  38          * there is no need to unstall the root domain by ourselves
  39          * afterwards.
  40          */
  41         p0.l = _bfin_irq_flags;
  42         p0.h = _bfin_irq_flags;
  43         r4 = [p0];
  44         sti r4;
  45 #endif /* CONFIG_IPIPE */
  46         SP += -12;
  47         pseudo_long_call _schedule_tail, p5;
  48         SP += 12;
  49         p1 = [sp++];
  50         r0 = [sp++];
  51         cc = p1 == 0;
  52         if cc jump .Lfork;
  53         sp += -12;
  54         call (p1);
  55         sp += 12;
  56 .Lfork:
  57         RESTORE_CONTEXT
  58         rti;
  59 ENDPROC(_ret_from_fork)