root/arch/arm/lib/putuser.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  *  linux/arch/arm/lib/putuser.S
   4  *
   5  *  Copyright (C) 2001 Russell King
   6  *
   7  *  Idea from x86 version, (C) Copyright 1998 Linus Torvalds
   8  *
   9  * These functions have a non-standard call interface to make
  10  * them more efficient, especially as they return an error
  11  * value in addition to the "real" return value.
  12  *
  13  * __put_user_X
  14  *
  15  * Inputs:      r0 contains the address
  16  *              r1 contains the address limit, which must be preserved
  17  *              r2, r3 contains the value
  18  * Outputs:     r0 is the error code
  19  *              lr corrupted
  20  *
  21  * No other registers must be altered.  (see <asm/uaccess.h>
  22  * for specific ASM register usage).
  23  *
  24  * Note that ADDR_LIMIT is either 0 or 0xc0000000
  25  * Note also that it is intended that __put_user_bad is not global.
  26  */
  27 #include <linux/linkage.h>
  28 #include <asm/assembler.h>
  29 #include <asm/errno.h>
  30 #include <asm/domain.h>
  31 
  32 ENTRY(__put_user_1)
  33         check_uaccess r0, 1, r1, ip, __put_user_bad
  34 1: TUSER(strb)  r2, [r0]
  35         mov     r0, #0
  36         ret     lr
  37 ENDPROC(__put_user_1)
  38 
  39 ENTRY(__put_user_2)
  40         check_uaccess r0, 2, r1, ip, __put_user_bad
  41 #if __LINUX_ARM_ARCH__ >= 6
  42 
  43 2: TUSER(strh)  r2, [r0]
  44 
  45 #else
  46 
  47         mov     ip, r2, lsr #8
  48 #ifndef __ARMEB__
  49 2: TUSER(strb)  r2, [r0], #1
  50 3: TUSER(strb)  ip, [r0]
  51 #else
  52 2: TUSER(strb)  ip, [r0], #1
  53 3: TUSER(strb)  r2, [r0]
  54 #endif
  55 
  56 #endif /* __LINUX_ARM_ARCH__ >= 6 */
  57         mov     r0, #0
  58         ret     lr
  59 ENDPROC(__put_user_2)
  60 
  61 ENTRY(__put_user_4)
  62         check_uaccess r0, 4, r1, ip, __put_user_bad
  63 4: TUSER(str)   r2, [r0]
  64         mov     r0, #0
  65         ret     lr
  66 ENDPROC(__put_user_4)
  67 
  68 ENTRY(__put_user_8)
  69         check_uaccess r0, 8, r1, ip, __put_user_bad
  70 #ifdef CONFIG_THUMB2_KERNEL
  71 5: TUSER(str)   r2, [r0]
  72 6: TUSER(str)   r3, [r0, #4]
  73 #else
  74 5: TUSER(str)   r2, [r0], #4
  75 6: TUSER(str)   r3, [r0]
  76 #endif
  77         mov     r0, #0
  78         ret     lr
  79 ENDPROC(__put_user_8)
  80 
  81 __put_user_bad:
  82         mov     r0, #-EFAULT
  83         ret     lr
  84 ENDPROC(__put_user_bad)
  85 
  86 .pushsection __ex_table, "a"
  87         .long   1b, __put_user_bad
  88         .long   2b, __put_user_bad
  89 #if __LINUX_ARM_ARCH__ < 6
  90         .long   3b, __put_user_bad
  91 #endif
  92         .long   4b, __put_user_bad
  93         .long   5b, __put_user_bad
  94         .long   6b, __put_user_bad
  95 .popsection