arch/tile/kernel/entry.S

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #include <linux/linkage.h>
  16 #include <linux/unistd.h>
  17 #include <asm/irqflags.h>
  18 #include <asm/processor.h>
  19 #include <arch/abi.h>
  20 #include <arch/spr_def.h>
  21
  22 #ifdef __tilegx__
  23 #define bnzt bnezt
  24 #endif
  25
  26 STD_ENTRY(current_text_addr)
  27         { move r0, lr; jrp lr }
  28         STD_ENDPROC(current_text_addr)
  29
  30 /*
  31  * Implement execve().  The i386 code has a note that forking from kernel
  32  * space results in no copy on write until the execve, so we should be
  33  * careful not to write to the stack here.
  34  */
  35 STD_ENTRY(kernel_execve)
  36         moveli TREG_SYSCALL_NR_NAME, __NR_execve
  37         swint1
  38         jrp lr
  39         STD_ENDPROC(kernel_execve)
  40
  41 /* Delay a fixed number of cycles. */
  42 STD_ENTRY(__delay)
  43         { addi r0, r0, -1; bnzt r0, . }
  44         jrp lr
  45         STD_ENDPROC(__delay)
  46
  47 /*
  48  * We don't run this function directly, but instead copy it to a page
  49  * we map into every user process.  See vdso_setup().
  50  *
  51  * Note that libc has a copy of this function that it uses to compare
  52  * against the PC when a stack backtrace ends, so if this code is
  53  * changed, the libc implementation(s) should also be updated.
  54  */
  55         .pushsection .data
  56 ENTRY(__rt_sigreturn)
  57         moveli TREG_SYSCALL_NR_NAME,__NR_rt_sigreturn
  58         swint1
  59         ENDPROC(__rt_sigreturn)
  60         ENTRY(__rt_sigreturn_end)
  61         .popsection
  62
  63 STD_ENTRY(dump_stack)
  64         { move r2, lr; lnk r1 }
  65         { move r4, r52; addli r1, r1, dump_stack - . }
  66         { move r3, sp; j _dump_stack }
  67         jrp lr   /* keep backtracer happy */
  68         STD_ENDPROC(dump_stack)
  69
  70 STD_ENTRY(KBacktraceIterator_init_current)
  71         { move r2, lr; lnk r1 }
  72         { move r4, r52; addli r1, r1, KBacktraceIterator_init_current - . }
  73         { move r3, sp; j _KBacktraceIterator_init_current }
  74         jrp lr   /* keep backtracer happy */
  75         STD_ENDPROC(KBacktraceIterator_init_current)
  76
  77 /*
  78  * Reset our stack to r1/r2 (sp and ksp0+cpu respectively), then
  79  * free the old stack (passed in r0) and re-invoke cpu_idle().
  80  * We update sp and ksp0 simultaneously to avoid backtracer warnings.
  81  */
  82 STD_ENTRY(cpu_idle_on_new_stack)
  83         {
  84          move sp, r1
  85          mtspr SPR_SYSTEM_SAVE_K_0, r2
  86         }
  87         jal free_thread_info
  88         j cpu_idle
  89         STD_ENDPROC(cpu_idle_on_new_stack)
  90
  91 /* Loop forever on a nap during SMP boot. */
  92 STD_ENTRY(smp_nap)
  93         nap
  94         j smp_nap /* we are not architecturally guaranteed not to exit nap */
  95         jrp lr    /* clue in the backtracer */
  96         STD_ENDPROC(smp_nap)
  97
  98 /*
  99  * Enable interrupts racelessly and then nap until interrupted.
 100  * This function's _cpu_idle_nap address is special; see intvec.S.
 101  * When interrupted at _cpu_idle_nap, we bump the PC forward 8, and
 102  * as a result return to the function that called _cpu_idle().
 103  */
 104 STD_ENTRY(_cpu_idle)
 105         {
 106          lnk r0
 107          movei r1, KERNEL_PL
 108         }
 109         {
 110          addli r0, r0, _cpu_idle_nap - .
 111          mtspr INTERRUPT_CRITICAL_SECTION, r1
 112         }
 113         IRQ_ENABLE(r2, r3)             /* unmask, but still with ICS set */
 114         mtspr SPR_EX_CONTEXT_K_1, r1   /* Kernel PL, ICS clear */
 115         mtspr SPR_EX_CONTEXT_K_0, r0
 116         iret
 117         .global _cpu_idle_nap
 118 _cpu_idle_nap:
 119         nap
 120         jrp lr
 121         STD_ENDPROC(_cpu_idle)