root/arch/powerpc/kernel/vdso64/datapage.S

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Access to the shared data page by the vDSO & syscall map
   4  *
   5  * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
   6  */
   7 
   8 #include <asm/processor.h>
   9 #include <asm/ppc_asm.h>
  10 #include <asm/asm-offsets.h>
  11 #include <asm/unistd.h>
  12 #include <asm/vdso.h>
  13 
  14         .text
  15 .global __kernel_datapage_offset;
  16 __kernel_datapage_offset:
  17         .long   0
  18 
  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,data_page_branch
  31 data_page_branch:
  32         mflr    r3
  33         mtlr    r0
  34         addi    r3, r3, __kernel_datapage_offset-data_page_branch
  35         lwz     r0,0(r3)
  36   .cfi_restore lr
  37         add     r3,r0,r3
  38         blr
  39   .cfi_endproc
  40 V_FUNCTION_END(__get_datapage)
  41 
  42 /*
  43  * void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
  44  *
  45  * returns a pointer to the syscall map. the map is agnostic to the
  46  * size of "long", unlike kernel bitops, it stores bits from top to
  47  * bottom so that memory actually contains a linear bitmap
  48  * check for syscall N by testing bit (0x80000000 >> (N & 0x1f)) of
  49  * 32 bits int at N >> 5.
  50  */
  51 V_FUNCTION_BEGIN(__kernel_get_syscall_map)
  52   .cfi_startproc
  53         mflr    r12
  54   .cfi_register lr,r12
  55         mr      r4,r3
  56         bl      V_LOCAL_FUNC(__get_datapage)
  57         mtlr    r12
  58         addi    r3,r3,CFG_SYSCALL_MAP64
  59         cmpldi  cr0,r4,0
  60         crclr   cr0*4+so
  61         beqlr
  62         li      r0,NR_syscalls
  63         stw     r0,0(r4)
  64         blr
  65   .cfi_endproc
  66 V_FUNCTION_END(__kernel_get_syscall_map)
  67 
  68 
  69 /*
  70  * void unsigned long  __kernel_get_tbfreq(void);
  71  *
  72  * returns the timebase frequency in HZ
  73  */
  74 V_FUNCTION_BEGIN(__kernel_get_tbfreq)
  75   .cfi_startproc
  76         mflr    r12
  77   .cfi_register lr,r12
  78         bl      V_LOCAL_FUNC(__get_datapage)
  79         ld      r3,CFG_TB_TICKS_PER_SEC(r3)
  80         mtlr    r12
  81         crclr   cr0*4+so
  82         blr
  83   .cfi_endproc
  84 V_FUNCTION_END(__kernel_get_tbfreq)