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 /*
  42  * We don't run this function directly, but instead copy it to a page
  43  * we map into every user process.  See vdso_setup().
  44  *
  45  * Note that libc has a copy of this function that it uses to compare
  46  * against the PC when a stack backtrace ends, so if this code is
  47  * changed, the libc implementation(s) should also be updated.
  48  */
  49         .pushsection .data
  50 ENTRY(__rt_sigreturn)
  51         moveli TREG_SYSCALL_NR_NAME,__NR_rt_sigreturn
  52         swint1
  53         ENDPROC(__rt_sigreturn)
  54         ENTRY(__rt_sigreturn_end)
  55         .popsection
  56
  57 STD_ENTRY(dump_stack)
  58         { move r2, lr; lnk r1 }
  59         { move r4, r52; addli r1, r1, dump_stack - . }
  60         { move r3, sp; j _dump_stack }
  61         jrp lr   /* keep backtracer happy */
  62         STD_ENDPROC(dump_stack)
  63
  64 STD_ENTRY(KBacktraceIterator_init_current)
  65         { move r2, lr; lnk r1 }
  66         { move r4, r52; addli r1, r1, KBacktraceIterator_init_current - . }
  67         { move r3, sp; j _KBacktraceIterator_init_current }
  68         jrp lr   /* keep backtracer happy */
  69         STD_ENDPROC(KBacktraceIterator_init_current)
  70
  71 /*
  72  * Reset our stack to r1/r2 (sp and ksp0+cpu respectively), then
  73  * free the old stack (passed in r0) and re-invoke cpu_idle().
  74  * We update sp and ksp0 simultaneously to avoid backtracer warnings.
  75  */
  76 STD_ENTRY(cpu_idle_on_new_stack)
  77         {
  78          move sp, r1
  79          mtspr SPR_SYSTEM_SAVE_K_0, r2
  80         }
  81         jal free_thread_info
  82         j cpu_idle
  83         STD_ENDPROC(cpu_idle_on_new_stack)
  84
  85 /* Loop forever on a nap during SMP boot. */
  86 STD_ENTRY(smp_nap)
  87         nap
  88         nop       /* avoid provoking the icache prefetch with a jump */
  89         j smp_nap /* we are not architecturally guaranteed not to exit nap */
  90         jrp lr    /* clue in the backtracer */
  91         STD_ENDPROC(smp_nap)
  92
  93 /*
  94  * Enable interrupts racelessly and then nap until interrupted.
  95  * Architecturally, we are guaranteed that enabling interrupts via
  96  * mtspr to INTERRUPT_CRITICAL_SECTION only interrupts at the next PC.
  97  * This function's _cpu_idle_nap address is special; see intvec.S.
  98  * When interrupted at _cpu_idle_nap, we bump the PC forward 8, and
  99  * as a result return to the function that called _cpu_idle().
 100  */
 101 STD_ENTRY(_cpu_idle)
 102         movei r1, 1
 103         IRQ_ENABLE_LOAD(r2, r3)
 104         mtspr INTERRUPT_CRITICAL_SECTION, r1
 105         IRQ_ENABLE_APPLY(r2, r3)       /* unmask, but still with ICS set */
 106         mtspr INTERRUPT_CRITICAL_SECTION, zero
 107         .global _cpu_idle_nap
 108 _cpu_idle_nap:
 109         nap
 110         nop       /* avoid provoking the icache prefetch with a jump */
 111         jrp lr
 112         STD_ENDPROC(_cpu_idle)