arch/arm/lib/getuser.S

   1 /*
   2  *  linux/arch/arm/lib/getuser.S
   3  *
   4  *  Copyright (C) 2001 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  Idea from x86 version, (C) Copyright 1998 Linus Torvalds
  11  *
  12  * These functions have a non-standard call interface to make them more
  13  * efficient, especially as they return an error value in addition to
  14  * the "real" return value.
  15  *
  16  * __get_user_X
  17  *
  18  * Inputs:      r0 contains the address
  19  *              r1 contains the address limit, which must be preserved
  20  * Outputs:     r0 is the error code
  21  *              r2 contains the zero-extended value
  22  *              lr corrupted
  23  *
  24  * No other registers must be altered.  (see <asm/uaccess.h>
  25  * for specific ASM register usage).
  26  *
  27  * Note that ADDR_LIMIT is either 0 or 0xc0000000.
  28  * Note also that it is intended that __get_user_bad is not global.
  29  */
  30 #include <linux/linkage.h>
  31 #include <asm/assembler.h>
  32 #include <asm/errno.h>
  33 #include <asm/domain.h>
  34
  35 ENTRY(__get_user_1)
  36         check_uaccess r0, 1, r1, r2, __get_user_bad
  37 1: TUSER(ldrb)  r2, [r0]
  38         mov     r0, #0
  39         mov     pc, lr
  40 ENDPROC(__get_user_1)
  41
  42 ENTRY(__get_user_2)
  43         check_uaccess r0, 2, r1, r2, __get_user_bad
  44 #ifdef CONFIG_CPU_USE_DOMAINS
  45 rb      .req    ip
  46 2:      ldrbt   r2, [r0], #1
  47 3:      ldrbt   rb, [r0], #0
  48 #else
  49 rb      .req    r0
  50 2:      ldrb    r2, [r0]
  51 3:      ldrb    rb, [r0, #1]
  52 #endif
  53 #ifndef __ARMEB__
  54         orr     r2, r2, rb, lsl #8
  55 #else
  56         orr     r2, rb, r2, lsl #8
  57 #endif
  58         mov     r0, #0
  59         mov     pc, lr
  60 ENDPROC(__get_user_2)
  61
  62 ENTRY(__get_user_4)
  63         check_uaccess r0, 4, r1, r2, __get_user_bad
  64 4: TUSER(ldr)   r2, [r0]
  65         mov     r0, #0
  66         mov     pc, lr
  67 ENDPROC(__get_user_4)
  68
  69 __get_user_bad:
  70         mov     r2, #0
  71         mov     r0, #-EFAULT
  72         mov     pc, lr
  73 ENDPROC(__get_user_bad)
  74
  75 .pushsection __ex_table, "a"
  76         .long   1b, __get_user_bad
  77         .long   2b, __get_user_bad
  78         .long   3b, __get_user_bad
  79         .long   4b, __get_user_bad
  80 .popsection