LXR linux/arch/i386/lib/getuser.S

   1/*
   2 * __get_user functions.
   3 *
   4 * (C) Copyright 1998 Linus Torvalds
   5 *
   6 * These functions have a non-standard call interface
   7 * to make them more efficient, especially as they
   8 * return an error value in addition to the "real"
   9 * return value.
  10 */
  11#include <linux/linkage.h>
  12#include <asm/dwarf2.h>
  13#include <asm/thread_info.h>
  14
  15
  16/*
  17 * __get_user_X
  18 *
  19 * Inputs:      %eax contains the address
  20 *
  21 * Outputs:     %eax is error code (0 or -EFAULT)
  22 *              %edx contains zero-extended value
  23 *
  24 * These functions should not modify any other registers,
  25 * as they get called from within inline assembly.
  26 */
  27
  28.text
  29ENTRY(__get_user_1)
  30        CFI_STARTPROC
  31        GET_THREAD_INFO(%edx)
  32        cmpl TI_addr_limit(%edx),%eax
  33        jae bad_get_user
  341:      movzbl (%eax),%edx
  35        xorl %eax,%eax
  36        ret
  37        CFI_ENDPROC
  38ENDPROC(__get_user_1)
  39
  40ENTRY(__get_user_2)
  41        CFI_STARTPROC
  42        addl $1,%eax
  43        jc bad_get_user
  44        GET_THREAD_INFO(%edx)
  45        cmpl TI_addr_limit(%edx),%eax
  46        jae bad_get_user
  472:      movzwl -1(%eax),%edx
  48        xorl %eax,%eax
  49        ret
  50        CFI_ENDPROC
  51ENDPROC(__get_user_2)
  52
  53ENTRY(__get_user_4)
  54        CFI_STARTPROC
  55        addl $3,%eax
  56        jc bad_get_user
  57        GET_THREAD_INFO(%edx)
  58        cmpl TI_addr_limit(%edx),%eax
  59        jae bad_get_user
  603:      movl -3(%eax),%edx
  61        xorl %eax,%eax
  62        ret
  63        CFI_ENDPROC
  64ENDPROC(__get_user_4)
  65
  66bad_get_user:
  67        CFI_STARTPROC
  68        xorl %edx,%edx
  69        movl $-14,%eax
  70        ret
  71        CFI_ENDPROC
  72END(bad_get_user)
  73
  74.section __ex_table,"a"
  75        .long 1b,bad_get_user
  76        .long 2b,bad_get_user
  77        .long 3b,bad_get_user
  78.previous
  79