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 .global __kernel_datapage_offset;
  20 __kernel_datapage_offset:
  21         .long   0
  22
  23 V_FUNCTION_BEGIN(__get_datapage)
  24   .cfi_startproc
  25         /* We don't want that exposed or overridable as we want other objects
  26          * to be able to bl directly to here
  27          */
  28         .protected __get_datapage
  29         .hidden __get_datapage
  30
  31         mflr    r0
  32   .cfi_register lr,r0
  33
  34         bcl     20,31,data_page_branch
  35 data_page_branch:
  36         mflr    r3
  37         mtlr    r0
  38         addi    r3, r3, __kernel_datapage_offset-data_page_branch
  39         lwz     r0,0(r3)
  40         add     r3,r0,r3
  41         blr
  42   .cfi_endproc
  43 V_FUNCTION_END(__get_datapage)
  44
  45 /*
  46  * void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
  47  *
  48  * returns a pointer to the syscall map. the map is agnostic to the
  49  * size of "long", unlike kernel bitops, it stores bits from top to
  50  * bottom so that memory actually contains a linear bitmap
  51  * check for syscall N by testing bit (0x80000000 >> (N & 0x1f)) of
  52  * 32 bits int at N >> 5.
  53  */
  54 V_FUNCTION_BEGIN(__kernel_get_syscall_map)
  55   .cfi_startproc
  56         mflr    r12
  57   .cfi_register lr,r12
  58         mr      r4,r3
  59         bl      V_LOCAL_FUNC(__get_datapage)
  60         mtlr    r12
  61         addi    r3,r3,CFG_SYSCALL_MAP64
  62         cmpldi  cr0,r4,0
  63         crclr   cr0*4+so
  64         beqlr
  65         li      r0,NR_syscalls
  66         stw     r0,0(r4)
  67         blr
  68   .cfi_endproc
  69 V_FUNCTION_END(__kernel_get_syscall_map)
  70
  71
  72 /*
  73  * void unsigned long  __kernel_get_tbfreq(void);
  74  *
  75  * returns the timebase frequency in HZ
  76  */
  77 V_FUNCTION_BEGIN(__kernel_get_tbfreq)
  78   .cfi_startproc
  79         mflr    r12
  80   .cfi_register lr,r12
  81         bl      V_LOCAL_FUNC(__get_datapage)
  82         ld      r3,CFG_TB_TICKS_PER_SEC(r3)
  83         mtlr    r12
  84         crclr   cr0*4+so
  85         blr
  86   .cfi_endproc
  87 V_FUNCTION_END(__kernel_get_tbfreq)