arch/powerpc/kernel/vdso64/datapage.S

   1 /*
   2  * Access to the shared data page by the vDSO & syscall map
   3  *
   4  * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <asm/processor.h>
  13 #include <asm/ppc_asm.h>
  14 #include <asm/asm-offsets.h>
  15 #include <asm/unistd.h>
  16 #include <asm/vdso.h>
  17
  18         .text
  19 V_FUNCTION_BEGIN(__get_datapage)
  20   .cfi_startproc
  21         /* We don't want that exposed or overridable as we want other objects
  22          * to be able to bl directly to here
  23          */
  24         .protected __get_datapage
  25         .hidden __get_datapage
  26
  27         mflr    r0
  28   .cfi_register lr,r0
  29
  30         bcl     20,31,1f
  31         .global __kernel_datapage_offset;
  32 __kernel_datapage_offset:
  33         .long   0
  34 1:
  35         mflr    r3
  36         mtlr    r0
  37         lwz     r0,0(r3)
  38         add     r3,r0,r3
  39         blr
  40   .cfi_endproc
  41 V_FUNCTION_END(__get_datapage)
  42
  43 /*
  44  * void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
  45  *
  46  * returns a pointer to the syscall map. the map is agnostic to the
  47  * size of "long", unlike kernel bitops, it stores bits from top to
  48  * bottom so that memory actually contains a linear bitmap
  49  * check for syscall N by testing bit (0x80000000 >> (N & 0x1f)) of
  50  * 32 bits int at N >> 5.
  51  */
  52 V_FUNCTION_BEGIN(__kernel_get_syscall_map)
  53   .cfi_startproc
  54         mflr    r12
  55   .cfi_register lr,r12
  56         mr      r4,r3
  57         bl      V_LOCAL_FUNC(__get_datapage)
  58         mtlr    r12
  59         addi    r3,r3,CFG_SYSCALL_MAP64
  60         cmpli   cr0,r4,0
  61         crclr   cr0*4+so
  62         beqlr
  63         li      r0,__NR_syscalls
  64         stw     r0,0(r4)
  65         blr
  66   .cfi_endproc
  67 V_FUNCTION_END(__kernel_get_syscall_map)
  68
  69
  70 /*
  71  * void unsigned long  __kernel_get_tbfreq(void);
  72  *
  73  * returns the timebase frequency in HZ
  74  */
  75 V_FUNCTION_BEGIN(__kernel_get_tbfreq)
  76   .cfi_startproc
  77         mflr    r12
  78   .cfi_register lr,r12
  79         bl      V_LOCAL_FUNC(__get_datapage)
  80         ld      r3,CFG_TB_TICKS_PER_SEC(r3)
  81         mtlr    r12
  82         crclr   cr0*4+so
  83         blr
  84   .cfi_endproc
  85 V_FUNCTION_END(__kernel_get_tbfreq)